Occupational and Environmental Medicine

About the journal

Publisher: BMJ Pub. Group
Published: 1994 to the present, England
Language: English
ISSN: 1351-0711 (print), 1470-7926 (electronic)
Continues: British Journal of Industrial Medicine
Its record in the NLM Catalog

2020s

Lung cancer risk prediction models and asbestos exposure: a validation study on the Western Australia Asbestos Review Program. C. Kumarasamy, K. Betts, R. Norman, et al. 2026;83(3):154-161. PubMed · Publisher · Free full text

Abstract

Objectives: Asbestos exposure raises the lung cancer risk and has supra-additive synergy alongside tobacco exposure. Lung cancer screening (LCS) is effective when high-risk populations are targeted. This study examined the utility of various LCS eligibility and risk prediction models in an asbestos-exposed population.

Methods: The Western Australia Asbestos Review Program (ARP) consists of individuals with known exposure to asbestos. All participants underwent annual review with low-dose CT screening. The performance of the Prostate, Lung, Colorectal and Ovarian (PLCO)m2012, PLCOm2014 and PLCOocc models, Liverpool Lung Project V.2 (LLPv2) and Bach models, together with the United States Preventive Services Task Force (USPSTF)2021 and Australian LCS eligibility criteria were validated on the ARP.

Results: The cohort consisted of 2126 participants of which 85.4% were male with a median (IQR) age of 70 (63-75) years old. Former smokers comprised 55.1% (n=1172) and never smokers 36.2% (n=769) of the cohort. Median smoking and cessation duration were 24 years (IQR: 13-72) and 32 years (IQR: 22-41), respectively. Lung cancer was diagnosed in 51 (2.4%) participants.When applying the risk models to the ARP cohort, the area under the curve for all models was modest, ranging from 0.602 to 0.675. All models underestimated risk in this cohort during calibration assessment, with the exception of the LLP V.2, which overestimated risk.

Conclusions: In an asbestos exposed population, current LCS eligibility criteria and risk models mostly underestimate the risk of lung cancer, reflecting the need for improved risk prediction models that adequately account for asbestos exposure.

© Author(s) (or their employer(s)) 2026. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.
Occupational exposure to chlorinated solvents and lung cancer: results of the SYNERGY case-control study. W. Wan, R. Vermeulen, L. Portengen, et al. 2026;83(1):54-57. PubMed · Publisher · Free full text

Abstract

Objective: The association between occupational exposure to chlorinated solvents and lung cancer remains inconclusive. This study investigated this relationship using data from the internationally pooled SYNERGY study.

Methods: Data from 14 case-control studies conducted in 13 European countries and Canada were pooled, including 28 048 participants (12 329 cases and 15 719 controls). Lifetime occupational exposure to chlorinated solvents was assessed using the ALOHA+job-exposure matrix. ORs and 95% CIs were estimated using unconditional logistic regression, adjusted for study centre, age, sex, smoking (pack-years and cessation), cumulative exposure to five occupational lung carcinogens (asbestos, hexavalent chromium, polycyclic aromatic hydrocarbons, respirable crystalline silica and diesel engine exhaust), cumulative benzene exposure and employment in high-risk occupations ('List A' jobs). Associations were estimated across categories of exposure levels, durations and analyses stratified by smoking status and lung cancer subtypes.

Results: We found no evidence of an association between ever exposure to chlorinated solvents and lung cancer risk (OR 1.03; 95% CI 0.96 to 1.10). Among exposed individuals, a positive trend with cumulative exposure was observed (p=0.031), but not when non-exposed individuals were included (p=0.173). Positive trends were found with exposure duration (p=0.005 for exposed; p=0.048 overall); risks were modestly elevated (OR 1.11) in those exposed for 20 or more years. No increased risk was observed across smoking strata or lung cancer subtypes.

Conclusions: This pooled analysis provides limited evidence of an association between occupational exposure to chlorinated solvents and lung cancer, though exposure-response trends were noted among exposed individuals.

© Author(s) (or their employer(s)) 2026. No commercial re-use. See rights and permissions. Published by BMJ Group.
Mesothelioma risks and cumulative exposure to elongate mineral particles of various sizes in Minnesota taconite mining industry. Y. Shao, G. Ramachandran, J.H. Mandel, et al. 2025;82(1):7-13. PubMed · Publisher · Free full text

Abstract

Objectives: An excess of mesothelioma has been previously observed in iron ore miners in Northeastern Minnesota. This study explored the potential association between mesothelioma and elongate mineral particle (EMP) exposures in the Minnesota taconite mining industry, examining both regulated and non-regulated EMP dimensions.

Methods: A nested case-control study design within the Mineral Resources Health Assessment Programme cohort analysed 104 mesothelioma cases and 410 controls. Cumulative EMP exposures were assessed across various dimensional definitions, including regulated (National Institute for Occupational Safety and Health, NIOSH) and non-regulated EMPs. Conditional logistic regression models were applied to estimate mesothelioma risk linked to employment duration and cumulative EMP exposure while adjusting for potential confounding variables.

Results: Consistent with earlier assessments, mesothelioma was associated with the number of years employed in the taconite industry (rate ratio (RR) 1.02, 95% CI 1.00 to 1.05) and cumulative NIOSH EMP exposure ((EMP/cc)×years) in taconite mining and processing (RR 1.20, 95% CI 0.99 to 1.46). Positive associations were also observed with mesothelioma and cumulative exposure to non-regulated EMPs.

Conclusions: This study supported the main conclusions in the previous study that the data were consistent with an association between mesothelioma and employment duration and with NIOSH EMP exposure in taconite mining and processing. However, the 95% CI indicates the data are also compatible with a null effect. Given the limitations we cite in the manuscript, additional study is needed to clarify the effect. Additionally, this study found possible evidence of a positive association between mesothelioma and cumulative exposure to Chatfield EMP, Suzuki EMP and Cleavage Fragments in the Minnesota taconite worker population.

© Author(s) (or their employer(s)) 2025. No commercial re-use. See rights and permissions. Published by BMJ Group.
Occupational asbestos exposure and gastrointestinal cancers: systematic review and meta-analyses. M. Koehoorn, C.B. McLeod, J. Fan, et al. 2025;81(12):639-646. Systematic review · Meta-analysis PubMed · Publisher

Abstract

Objective: To conduct meta-analyses of occupational asbestos exposure and oesophageal, stomach and colorectal cancer risk, including a critical exposure assessment approach.

Methods: The search strategy was executed on MEDLINE, Embase, CINAHL, Scopus and Web of Science databases (March 2022, March 2024). Effect estimates (ORs, HRs, standardised incidence ratio and standardised mortality ratio) from eligible cohort and case-control studies were combined in random effects models. Meta-relative risks (mRRs) were calculated by cancer site and exposure characteristics. Investigators with occupational epidemiology and hygiene expertise came to a consensus on the estimates where there was confidence in significant asbestos exposure.

Results: A total of 82 (oesophageal), 153 (stomach) and 144 (colorectal) papers met the inclusion criteria. Elevated mRRs were observed for any occupational asbestos exposure for oesophageal (1.17 (95% CI 1.07 to 1.29)), stomach (1.14 (95% CI 1.05 to 1.23)) and colorectal cancer (1.16 (95% CI 1.08 to 1.24)). There was consistency of mRR estimates and higher mRRs in meta-analyses where there was increased confidence in the categorisation of highly exposed workers, including among the highest exposed workers in exposure-response studies (oesophageal: 1.63 (95% CI 1.29 to 2.06); stomach: 1.28 (95% CI 1.09 to 1.52); colorectal: 1.29 (95% CI 1.09 to 1.53)), among asbestos insulation workers (oesophageal: 1.68 (95% 1.19 to 2.36); stomach: 1.53 (95% 0.93 to 2.51); colorectal: 1.59 (95% 1.14 to 2.23)) and among workers in cohorts with a twofold or greater risk of asbestos-related lung cancer (oesophageal: 1.40 (95% CI 1.14 to 1.71); stomach: 1.33 (95% CI 1.14 to 1.56); colorectal: 1.47 (95% CI 1.34 to 1.61)).

Conclusion: The meta-analyses support a causal link between occupational asbestos exposure and the risk of oesophageal, stomach and colorectal cancer.

© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.
Peritoneal mesothelioma and asbestos exposure: a population-based case-control study in Italy, 2000-2021. D. Consonni, E. Migliore, M. Gangemi, et al. 2025;82(10):495-503. PubMed · Publisher · Free full text

Abstract

Objectives: Using a case-control design, we examined the association between occupational asbestos exposure and risk of peritoneal mesothelioma in the general population in Italy.

Methods: From the National Mesothelioma Registry, we selected cases (2000-2021) with life-time occupational history. Controls were 3045 from three case-control studies (region-sex-age-matched, performed in six regions), one in 2002-2004 (2116 population controls) and two in 2012-2016 (718 population and 211 hospital controls). For all subjects, exposure assignment was based on a quantitative job-exposure matrix (SYN-JEM). Qualitative expert-based evaluation was available for all cases, but only in 2012-2016 for 929 controls. We estimated ORs and 90% CIs using logistic regression models adjusted for residence, gender, period and age.

Results: In complete analyses (1591 cases, all years/regions), the OR for ever exposure was 3.66 (CI 3.21 to 4.18, 45.4% cases and 27.8% controls exposed). Among the exposed, median cumulative exposure (fibres/mL-years) was 1.4 (max 20.0) in cases and 1.1 (max 10.9) in controls. The OR was 1.55 (1.48 to 1.62) per log10-transformed cumulative exposure. In analyses restricted to 290 cases (same years/regions of controls), ORs were 3.35 (2.57 to 4.37, 43.8% cases exposed) for ever exposure and 1.52 (1.39 to 1.65) for cumulative exposure. ORs for ever asbestos exposure using expert-based evaluation were particularly high, 4.32 (3.50 to 5.34, 53.9% cases and 26.4% controls exposed) in complete analyses (778 cases) and 6.35 (4.58 to 8.81, 57.1% cases exposed) in restricted analyses (245 cases), but are known to be more prone to bias.

Conclusions: Peritoneal mesothelioma showed clear associations with asbestos exposure using different exposure assessment methods.

© Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.
Applying a 'presumably plausible' principle in a new one-time financial compensation system for occupational diseases in the Netherlands. P. Coenen, S. Kezic, D.J.J. Heederik, et al. 2024;81(10):529-531. PubMed · Publisher

Abstract

Objectives: In the Netherlands, a new regulation has been adopted for recognition and compensation of serious substance-related occupational diseases. A national advisory committee has a key task of providing advice on the protocols for operationalisation of individual causality assessment in this new context.

Methods: Protocol development involves gathering the best available population-level evidence on causality and using this evidence to determine individual causality. Here, the presumably plausible principle was adopted, which stipulates that uncertainties in individual causality should be weighed in favour of a fast and transparent one-time compensation for (ex-)workers.

Results: In monocausal diseases, a limited workplace exposure assessment is considered sufficient to determine whether individual causality is presumably plausible in the Dutch context. For multicausal occupational diseases, individual causality assessment is more complicated. Modelling of existing data on the exposure-response relation helps establish the probability of causation, that is, the risk of the disease attributable to a work-related exposure. This operationalisation, applied in some protocols, makes use of the probability of causation, while being prudent in establishing exposure limits. An example from asbestos and lung cancer is provided in this short report.

Conclusions: We propose a pragmatic approach to individual causality assessment of substance-related occupational diseases, considering statistical and diagnostic uncertainties. This approach substantiates protocols towards a one-time financial compensation without long-winding recognition procedures.

© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.
Benzene exposure and risk of lung cancer in the Norwegian Offshore Petroleum Worker cohort: a prospective case-cohort study. R. Babigumira, M.B. Veierød, H.D. Hosgood, et al. 2024;81(1):9-16. PubMed · Publisher · Free full text

Abstract

Objective: The objective of our study was to examine whether occupational exposure to benzene is associated with lung cancer among males in the Norwegian Offshore Petroleum Workers cohort.

Methods: Among 25 347 male offshore workers employed during 1965-1998, we conducted a case-cohort study with 399 lung cancer cases diagnosed between 1999 and 2021, and 2035 non-cases sampled randomly by 5-year birth cohorts. Individual work histories were coupled to study-specific job-exposure matrices for benzene and other known lung carcinogens. Weighted Cox regression was used to estimate HRs and 95% CIs for the associations between benzene exposure and lung cancer, by major histological subtypes, adjusted for age, smoking and occupational exposure to welding fumes, asbestos and crystalline silica. Missing data were imputed.

Results: For lung cancer (all subtypes combined), HRs (95% CIs) for the highest quartiles of benzene exposure versus unexposed were 1.15 (0.61 to 2.35) for cumulative exposure, 1.43 (0.76 to 2.69) for duration, and 1.22 (0.68 to 2.18) for average intensity (0.280≤P-trend≤0.741). For 152 adenocarcinoma cases, a positive trend was observed for exposure duration (P-trend=0.044).

Conclusions: In this cohort of offshore petroleum workers generally exposed to low average levels of benzene, we did not find an overall clear support for an association with lung cancer (all subtypes combined), although an association was suggested for duration of benzene exposure and adenocarcinoma. The limited evidence might be due to restricted statistical power.

© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ.
Exposure to fibres and risk of pleural mesothelioma in the Norwegian Offshore Petroleum Workers cohort. L.A.M. Berge, N.K. Shala, F. Barone-Adesi, et al. 2024;81(7):331-338. PubMed · Publisher

Abstract

Objectives: Pleural mesothelioma is a rare respiratory cancer, mainly caused by inhalation of asbestos fibres. Other inorganic fibres are also suggested risk factors. We aimed to investigate the association between exposure to asbestos or refractory ceramic fibres (RCFs) and pleural mesothelioma among male Norwegian offshore petroleum workers.

Methods: Among 25 347 men in the Norwegian Offshore Petroleum Workers (NOPW) cohort (1965-1998), 43 pleural mesothelioma cases were identified through the Cancer Registry of Norway (1999-2022). A case-cohort study was conducted with 2095 randomly drawn non-cases from the cohort. Asbestos and RCF exposures were assessed with expert-made job-exposure matrices (JEMs). Weighted Cox regression was used to estimate HRs and 95% CIs, adjusted for age at baseline and pre-offshore employment with likely asbestos exposure.

Results: An increased risk of pleural mesothelioma was indicated for the highest versus lowest tertile of average intensity of asbestos (HR=1.21, 95% CI: 0.57 to 2.54). Pre-offshore asbestos exposure (vs no such exposure) was associated with increased risk of pleural mesothelioma (HR=2.06, 95% CI: 1.11 to 3.81). For offshore workers with no pre-offshore asbestos exposure, an increased risk of pleural mesothelioma was found for the highest tertile of average intensity of asbestos (HR=4.13, 95% CI: 0.93 to 18), versus the lowest tertile. No associations were found between RCF and pleural mesothelioma.

Conclusions: Associations between JEM-based offshore asbestos exposure and pleural mesothelioma were confirmed in the NOPW cohort. Pleural mesothelioma risk was also associated with asbestos exposure before work in the offshore petroleum industry.

© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.
Ovarian cancer deaths attributable to asbestos exposure in Lombardy (Italy) in 2000-2018. G. Stoppa, C. Mensi, L. Fazzo, et al. 2024;81(7):359-365. PubMed · Publisher · Free full text

Abstract

Objectives: We aimed to estimate the fraction of deaths from ovarian cancer attributable to asbestos exposure in Lombardy Region, Italy, using a novel approach that exploits the fact that ovarian cancer asbestos exposure is associated with pleural cancer and other risk factors for breast cancer.

Methods: This ecological study is based on the Italian National Institute of Statistics mortality data. We formulate a trivariate Bayesian joint disease model to estimate the attributable fraction (AF) and the number of ovarian cancer deaths attributable to asbestos exposure from the geographic distribution of ovarian, pleural and breast cancer mortality at the municipality level from 2000 to 2018. Expected deaths and standardised mortality ratios were calculated using regional rates.

Results: We found shared dependencies between ovarian and pleural cancer, which capture risk factors common to the two diseases (asbestos exposure), and a spatially structured clustering component shared between ovarian and breast cancer, capturing other risk factors. Based on 10 462 ovarian cancer deaths, we estimated that 574 (95% credibility interval 388-819) were attributable to asbestos (AF 5.5%; 95% credibility interval 3.7-7.8). AF reaches 34%-47% in some municipalities with known heavy asbestos pollution.

Conclusions: The impact of asbestos on ovarian cancer occurrence can be relevant, particularly in areas with high asbestos exposure. Estimating attributable cases was possible only by using advanced Bayesian modelling to consider other risk factors for ovarian cancer. These findings are instrumental in tailoring public health surveillance programmes and implementing compensation and prevention policies.

© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.
Relationships between asbestos exposure and pleural plaques: dose and time effects using fractional polynomials. M. Menant, I. Benlala, I. Thaon, et al. 2024;81(6):313-319. PubMed · Publisher · Free full text

Abstract

Objective: The aim of this study was to confirm the relationship between several parameters of exposure to asbestos and pleural plaques (PP) using data from a large cohort of retired workers occupationally exposed to asbestos in France.

Method: A large screening programme, including high-resolution CT (HRCT) examinations at inclusion and two other HRCT campaigns, was organised from 2003 to 2016 in four regions of France for voluntary, formerly asbestos-exposed workers. Exposure to asbestos has been evaluated by industrial hygienists based on the complete work history. The time since first exposure, the time since last exposure, Cumulative Exposure Index and maximum level of exposure to asbestos, were used in logistic regression using fractional polynomials to model the relationship with PP.

Results: The study included 5392 subjects with at least one HRCT available. There was a significant non-linear effect of time since first exposure, time since last exposure and Cumulative Exposure Index to asbestos on the presence of PP. The risk of PP increased with increasing Cumulative Exposure Index to asbestos adjusted for time since first exposure, age and smoking status. Models also show that PP odds rise with increasing time since first exposure adjusted for cumulative index exposure, age and smoking status. PP odds decrease when time since last exposure increases.

Conclusion: The study provides new data on the link between asbestos exposure and the presence of PP using fractional polynomials with non-linear relationships for time exposure parameters and asbestos exposure parameters.

© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ.
Correction: What role for asbestos in idiopathic pulmonary fibrosis? Findings from the IPF job exposures case-control study. 2023;80(6):e1. PubMed · Publisher · Free full text
Incidence and mortality from malignant mesothelioma 1982-2020 and relationship with asbestos exposure: the Australian Mesothelioma Registry. K. Walker-Bone, G. Benke, E. MacFarlane, et al. 2023;80(4):186-191. PubMed · Publisher

Abstract

Objectives: Malignant mesothelioma is an uncommon cancer associated with asbestos exposure, predominantly occupational. Asbestos has been banned in Australia since 2003 but mesothelioma has a long latency and incident cases continue to present. The Australian Mesothelioma Registry was incepted to collect systematic data about incidence and mortality alongside asbestos exposure.

Methods: Benefiting from the Australian national system of cancer notification, all incident cases of mesothelioma in all states and territories are fast-tracked and notified regularly. Notified patients are contacted asking for consent to collect exposure information, initially by postal questionnaire and subsequently by telephone interview. Age-standardised annual incidence rates and mortality rates were calculated. Asbestos exposure was categorised as occupational, non-occupational, neither or, both; and as low, or high, probability of exposure.

Results: Mesothelioma incidence appears to have peaked. The age-standardised incidence rates have declined steadily since the early 2000s (peaking in males at 5.9/100 000 and in all-persons at 3.2/100 000), driven by rates in males, who comprise the majority of diagnosed cases. Rates in women have remained fairly stable since that time. Age-standardised mortality rates have followed similar trends. Mesothelioma remains the most common in those aged over 80 years. Nearly all (94%) cases were linked with asbestos exposure (78% occupational in men; 6.8% in women).

Conclusions: With effective control of occupational asbestos use, the decline in age-standardised incidence and death rates has occurred. Incidence rates among women, in whom occupational asbestos exposure is rarely detectable, remain unchanged, pointing to the role of household and /or environmental asbestos exposure.

© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.
Incidence of mesothelioma in young people and causal exposure to asbestos in the Italian national mesothelioma registry (ReNaM). A. Marinaccio, D. Di Marzio, C. Mensi, et al. 2023;80(11):603-609. PubMed · Publisher

Abstract

Introduction: The epidemiological surveillance of mesothelioma incidence is a crucial key for investigating the occupational and environmental sources of asbestos exposure. The median age at diagnosis is generally high, according to the long latency of the disease. The purposes of this study are to analyse the incidence of mesothelioma in young people and to evaluate the modalities of asbestos exposure.

Methods: Incident malignant mesothelioma (MM) cases in the period 1993-2018 were retrieved from Italian national mesothelioma registry and analysed for gender, incidence period, morphology and exposure. Age-standardised rates have been calculated and the multiple correspondence analysis has been performed. The association between age and asbestos exposure has been tested by χ2 test.

Results: From 1993 to 2018, 30 828 incident MM cases have been collected and 1278 (4.1%) presented diagnosis at early age (≤50 years). There is a substantial association between age at diagnosis and the type of asbestos exposure and a significantly lower frequency of cases with occupational exposure to asbestos (497 cases vs 701 expected) in young people has been documented. Paraoccupational and environmental exposure to asbestos have been found more frequent in young MM cases (85 and 93 observed cases vs 52 and 44 expected cases, respectively).

Conclusions: Mesothelioma incidence surveillance at population level and the anamnestic individual research of asbestos exposure is a fundamental tool for monitoring asbestos exposure health effects, supporting the exposure risks prevention policies. Clusters of mesothelioma incident cases in young people are a significant signal of a potential non-occupational exposure to asbestos.

© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.
Malignant mesothelioma among US Medicare beneficiaries: incidence, prevalence and therapy, 2016-2019. L. Kurth, J.M. Mazurek, D.J. Blackley. 2023;80(2):86-92. PubMed · Publisher · Free full text

Abstract

Objectives: Mesothelioma is a rare, aggressive cancer caused by exposure to asbestos fibres. Mesothelioma patients who receive trimodal therapy (chemotherapy, surgical resection and radiation) survive longer than those who receive two or fewer therapy modalities. This study analyses the 2016-2019 Medicare claims data to estimate the burden of malignant mesothelioma and describe therapy patterns (when available) among continuously enrolled fee-for-service (FFS; Medicare parts A and B) beneficiaries.

Methods: We analysed claims and enrolment information from 42 529 117 FFS Medicare beneficiaries using three mesothelioma case definitions (broad, intermediate and narrow) with varying levels of diagnostic requirements. Results are presented as ranges of values for the three definitions.

Results: Among FFS beneficiaries, 8213-19 036 beneficiaries with mesothelioma were identified depending on the case definition. The annual prevalence per 100 000 beneficiaries ranged from 8.8 in 2016 (narrow) to 31.3 in 2019 (broad) and annual incidence per 100 000 beneficiaries ranged from 4.5 in 2019 (narrow) to 12.6 in 2017 (broad). Depending on the mesothelioma case definition, 41.8%-81.5% had available therapy claim information indicating that 7.6%-11.3% received chemotherapy alone, 1.3%-1.5% received radiation alone, and 14.3%-27.0% underwent surgery only, with 4.6%-10.5% receiving all three therapy modalities.

Conclusions: Mesothelioma was a prevalent disease among FFS Medicare beneficiaries during 2016-2019, and a limited proportion of beneficiaries received all three therapy modalities. Medicare data build on findings from cancer registry data to enhance our understanding of the mesothelioma burden and therapy patterns.

© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.
Occupational exposures of firefighting and urinary tract cancer risk among men in the Norwegian Fire Departments Cohort. N. Marjerrison, T.K. Grimsrud, J. Hansen, et al. 2023;80(12):659-666. PubMed · Publisher · Free full text

Abstract

Objectives: Increased risks of bladder cancer and mesothelioma were the strongest evidence for the recent reclassification of firefighting as carcinogenic (Group 1) by the International Agency for Research on Cancer. Our study aim was to develop indicators for specific firefighting exposures and examine associations with urinary tract cancer (UTC), including bladder cancer.

Methods: We developed indicators for exposure from employment at a fire department or in firefighting jobs, to fire and smoke, and to diesel exhaust for men in the Norwegian Fire Departments Cohort (n=4250). Incident UTC cases were obtained from the Cancer Registry of Norway (1960-2021). Poisson regression was used to estimate incidence rate ratios (IRR) with cumulative exposures grouped into tertiles (reference: lowest exposed tertile) with 0-year, 10-year and 15-year lagging of exposures.

Results: During 125 090 person-years of follow-up, there were 76 cases of UTC. IRRs were mostly non-significantly increased in the middle tertile and at or below 1 in the highest tertile for total duration of employment, number of fires attended and fire exposure score with and without lags. In the middle tertile for diesel exhaust exposure, UTC risk was elevated over twofold with 10-year (IRR 2.27, 95% CI 1.22 to 4.20) and 15- year (2.21, 1.18 to 4.16) lags, and near 1 in the highest tertile. Findings for bladder cancer were similar to those for UTC.

Conclusions: Dose-response associations between the exposure indicators and UTC were not observed. Future studies using the indicators with more cases are needed.

© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.
What role for asbestos in idiopathic pulmonary fibrosis? Findings from the IPF job exposures case-control study. C.J. Reynolds, R. Sisodia, C. Barber, et al. 2023;80(2):97-103. PubMed · Publisher · Free full text

Abstract

Background: Asbestos has been hypothesised as the cause of the recent global increase in the incidence of 'idiopathic' pulmonary fibrosis (IPF). Establishing this has important diagnostic and therapeutic implications. The association between occupational asbestos exposure and IPF, and interaction with a common (minor allele frequency of 9% in European populations) genetic variant associated with IPF, MUC5B rs35705950, is unknown.

Methods: Multicentre, incident case-control study. Cases (n=494) were men diagnosed with IPF at 21 UK hospitals. Controls (n=466) were age-matched men who attended a hospital clinic in the same period. Asbestos exposure was assessed at interview using a validated job exposure matrix and a source-receptor model. The primary outcome was the association between asbestos exposure and IPF, estimated using logistic regression adjusted for age, smoking and centre. Interaction with MUC5B rs35705950 was investigated using a genetic dominant model.

Results: 327 (66%) cases and 293 (63%) controls ever had a high or medium asbestos exposure risk job; 8% of both cases and controls had cumulative exposure estimates ≥25 fibre ml⁻¹ years. Occupational asbestos exposure was not associated with IPF, adjusted OR 1.1 (95% CI 0.8 to 1.4; p=0.6) and there was no gene-environment interaction (p=0.3). Ever smoking was associated with IPF, OR 1.4 (95% CI 1 to 1.9; p=0.04) and interacted with occupational asbestos exposure, OR 1.9 (95% CI 1 to 3.6; p=0.04). In a further non-specified analysis, when stratifying for genotype there was significant interaction between smoking and work in an exposed job (p<0.01) for carriers of the minor allele of MUC5B rs35705950.

Conclusion: Occupational asbestos exposure alone, or through interaction with MUC5B rs35705950 genotype, was not associated with IPF. Exposure to asbestos and smoking interact to increase IPF risk in carriers of a common genetic variant, the minor allele of MUC5B rs35705950.

Trial Registration Number: NCT03211507.

© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.
Workers in Australian prebake aluminium smelters: update on risk of mortality and cancer incidence in the Healthwise cohort. A. Del Monaco, C. Dimitriadis, S. Xie, et al. 2023;80(3):160-169. PubMed · Publisher

Abstract

Objectives: To investigate mortality and the rates of incident cancer among a cohort of aluminium industry workers.

Methods: Among 4507 male employees who worked in either of two Australian prebake smelters for at least 3 months, data linkage was undertaken with the Australian National Death Index and Australian Cancer Database. Standardised Mortality Ratios (SMRs) and Standardised Incidence Rates (SIRs) were estimated for the whole cohort and for: production; maintenance and office workers. SMRs and SIRs were calculated by time since first employment.

Results: Among production workers, there was an excess risk of mortality from mesothelioma (SMR 2.8, 95% CI 1.3 to 5.2), lung (SMR 1.4, 95% CI 1.0 to 1.8), prostate (SMR 1.9, 95% CI 1.3 to 2.7) and liver cancer (SMR 2.0, 95% CI 1.1 to 3.4) and the SIR was also increased for overall respiratory cancers, specifically lung cancers. An excess risk of death from stomach cancer (SMR 2.9, 95% CI 1.2 to 6.1) and Alzheimer's disease (SMR 3.4, 95% CI 1.1 to 7.9) was seen among maintenance workers. The overall risk of death was similar to that of the Australian general population, as was mortality from cancers overall and non-malignant respiratory disease.

Conclusions: No excess risk of death from bladder cancer or non-malignant respiratory disease was found. Excess lung cancer mortality and incidence may be explained by smoking and excess mortality from mesothelioma may be explained by asbestos exposure. An excess risk of mortality from liver and prostate cancer has been shown in production workers and requires further investigation.

© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.
Cancer risk among firefighters and police in the Ontario workforce. J. Sritharan, T.L. Kirkham, J. MacLeod, et al. 2022;79(8):533-539. PubMed · Publisher · Free full text

Abstract

Objective: Firefighters and police often work in high-stress, complex environments with known and suspected carcinogenic exposures. We aimed to characterise cancer incidence among firefighters and police.

Methods: The Occupational Disease Surveillance System (ODSS) was used to identify workers employed as firefighters or police in Ontario. A cohort of workers were identified using lost-time workers' compensation claims data and followed for cancer in the Ontario Cancer Registry (1983-2020). Cox proportional hazard models were used to estimate HRs and 95% CIs for primary site-specific cancer diagnoses adjusted for age at start of follow-up, birth year and sex.

Results: A total of 13 642 firefighters and 22 595 police were identified in the cohort. Compared with all other workers in the ODSS, firefighters and police had increased risk of prostate cancer (firefighters: HR=1.43, 95% CI 1.31 to 1.57; police: HR=1.47, 95% CI 1.35 to 1.59), colon cancer (firefighters: HR=1.39, 95% CI 1.19 to 1.63; police: HR=1.39, 95% CI 1.21 to 1.60) and skin melanoma (firefighters: HR=2.38, 95% CI 1.99 to 2.84; police: HR=2.27, 95% CI 1.96 to 2.62). Firefighters also had increased risk of cancer of the pancreas, testis and kidney, as well as non-Hodgkin's lymphoma and leukaemia. Police had increased risk of thyroid, bladder and female breast cancer. When compared directly with the police, firefighters had an elevated risk of mesothelioma and testicular cancer.

Conclusions: Firefighters and police demonstrated some similar as well as some unique cancer risks. Findings from this larger worker population may have important implications for workplace and policy-level changes to improve preventative measures and reduce potential exposures to known carcinogenic hazards.

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Comparison of cancer incidence and mortality in the Norwegian Fire Departments Cohort, 1960-2018. N. Marjerrison, J. Jakobsen, P.A. Demers, et al. 2022;79(11):736-743. PubMed · Publisher · Free full text

Abstract

Objectives: Elevated risk of cancer at several sites has been reported among firefighters, although with mixed findings. The purpose of this study was to calculate standardised incidence ratios (SIRs) and standardised mortality ratios (SMRs) for cancer and compare them to assess whether use of the different measures could be a source of inconsistencies in findings.

Methods: The Norwegian Fire Departments Cohort, comprising 4295 male employees who worked at 15 fire departments across Norway, was linked to health outcome registries for the period 1960-2018. SIRs and SMRs were derived using national reference rates.

Results: Overall, we observed elevated incidence of colon cancer (SIR, 95% CI 1.27, 1.01 to 1.58), mesothelioma (2.59, 1.12 to 5.11), prostate cancer (1.18, 1.03 to 1.34) and all sites combined (1.15, 1.08 to 1.23). Smaller, non-significant elevations were found for mortality of colon cancer (SMR, 95% CI 1.20, 0.84 to 1.67) and mesothelioma (1.66, 0.34 to 4.86), while SMR for prostate cancer was at unity. Potential errors were observed in some of the mortality data, notably for mesothelioma cases. Among those who died of cancer, 3.7% (n=14) did not have a prior diagnosis of malignancy at the same site group.

Conclusions: Assessment of incidence or mortality did not greatly influence the interpretation of results. The most prominent differences in SIR and SMR appeared to be due to inconsistencies between sites of cancer diagnosis and cause of death. The difference in SIR and SMR for prostate cancer suggested a detection bias from differential screening practices.

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Developing a company-specific job exposure matrix for the Asbest Chrysotile Cohort Study. E. Feletto, E.V. Kovalevskiy, S.J. Schonfeld, et al. 2022;79(5):339-346. PubMed · Publisher · Free full text

Abstract

Objectives: Exposure assessment for retrospective industrial cohorts are often hampered by limited availability of historical measurements. This study describes the development of company-specific job-exposure matrices (JEMs) based on measurements collected over five decades for a cohort study of 35 837 workers (Asbest Chrysotile Cohort Study) in the Russian Federation to estimate their cumulative exposure to chrysotile containing dust and fibres.

Methods: Almost 100 000 recorded stationary dust measurements were available from 1951-2001 (factories) and 1964-2001 (mine). Linear mixed models were used to extrapolate for years where measurements were not available or missing. Fibre concentrations were estimated using conversion factors based on side-by-side comparisons. Dust and fibre JEMs were developed and exposures were allocated by linking them to individual workers' detailed occupational histories.

Results: The cohort covered a total of 515 355 employment-years from 1930 to 2010. Of these individuals, 15% worked in jobs not considered professionally exposed to chrysotile. The median cumulative dust exposure was 26 mg/m3 years for the entire cohort and 37.2 mg/m3 years for those professionally exposed. Median cumulative fibre exposure was 16.4 fibre/cm3 years for the entire cohort and 23.4 fibre/cm3 years for those professionally exposed. Cumulative exposure was highly dependent on birth cohort and gender. Of those professionally exposed, women had higher cumulative exposures than men as they were more often employed in factories with higher exposure concentrations rather than in the mine.

Conclusions: Unique company-specific JEMs were derived using a rich measurement database that overlapped with most employment-years of cohort members and will enable estimation of quantitative exposure-response.

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Environmental exposure to asbestos and the risk of lung cancer: a systematic review and meta-analysis. K. Kwak, D. Kang, D. Paek. 2022;79(3):207-214. Meta-analysis · Systematic review PubMed · Publisher

Abstract

Asbestos is a carcinogen associated with lung cancer, but few studies have examined the increased risk of lung cancer due to environmental asbestos exposure. We performed a systematic review and meta-analysis to evaluate the association between environmental asbestos exposure and lung cancer. We searched for articles on non-occupational or environmental asbestos exposure and lung cancer in PubMed, EMBASE, CINAHL and Web of Science databases. Our review included 15 studies, and except studies on ingestion exposure we performed a meta-analysis for 13 studies with respect to the type of exposure (neighbourhood and domestic/household exposure). Subgroup analyses and meta-regression were also performed. A significant increase in the risk of lung cancer was found for neighbourhood exposure (1.48, 95% CI 1.18 to 1.86), while the risk was not significantly increased for domestic/household exposure (1.04, 95% CI 0.85 to 1.27). With regard to neighbourhood exposure, naturally occurring asbestos and women were both associated with a higher risk of lung cancer; however, such an increase was not significantly greater compared with that associated with other sources of asbestos exposure and men. Although cautious interpretation is needed due to the large degree of heterogeneity and the small number of included studies, our findings imply that living near the source of asbestos increases the risk of lung cancer.

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Head and neck cancer and asbestos exposure. B. Clin, C. Gramond, I. Thaon, et al. 2022;79(10):690-696. PubMed · Publisher · Free full text

Abstract

Objectives: The aim of this study was to analyse, within a French cohort of workers previously occupationally exposed to asbestos, incidence and mortality from various sites of head and neck cancers (larynx excluded) and to examine the potential link of these cancers with pleural plaques.

Methods: A 10-year follow-up study was conducted in the 13 481 male subjects included in the cohort between October 2003 and December 2005. Asbestos exposure was assessed by industrial hygienist analysis of a standardised questionnaire. The final cumulative exposure index (CEI; in equivalent fibres.years/mL) for each subject was calculated as the sum of each employment period's four-level CEI. The number of head and neck cancers recorded by the National Health Insurance fund was collected in order to conduct an incidence study. Complementary analysis was restricted to men who had performed at least one chest CT scan (N=4804). A mortality study was also conducted. We used a Cox model with age as the time axis variable adjusted for smoking, time since first exposure, CEI of exposure to asbestos and pleural plaques on CT scans.

Results: We reported a significant dose-response relationship between CEI of exposure to asbestos and head and neck cancers after exclusion of laryngeal cancers, in the mortality study (HR 1.03, 95% CI (1.01 to 1.06) for an increase of 10 f.years/mL) and a close to significant dose-response relationship in the incidence study (HR 1.02, 95% CI (1.00 to 1.04) for an increase of 10 f.years/mL). No statistically significant association between pleural plaques and head and neck cancer incidence was observed.

Conclusions: This large-scale study suggests a relationship between asbestos exposure and head and neck cancers, after exclusion of laryngeal cancers, regardless of whether associated pleural plaques were present.

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Pleural plaques and risk of lung cancer in workers formerly occupationally exposed to asbestos: extension of follow-up. J. Gallet, F. Laurent, C. Paris, et al. 2022. PubMed · Publisher

Abstract

Background: Occupational asbestos exposure is associated with pleural plaques (PP), a benign disease often seen as a marker of past exposure to asbestos and lung cancer. The association between these two diseases has not been formally proved, the aim of this study was to evaluate this association in the asbestos-related disease cohort (ARDCO) cohort.

Methods: ARDCO is a French multicentric cohort including workers formerly occupationally exposed to asbestos from 2003 to 2005. CT scan was performed to diagnose PP with double reading and lung cancer (incidence and mortality) was followed through health insurance data and death certificates. Cox models were used to estimate the association between PP and lung cancer adjusting for occupational asbestos exposure (represented by cumulative exposure index, time since first exposure and time since last exposure) and smoking status.

Results: A total of 176 cases (of 5050 subjects) and 88 deaths (of 4938 subjects) of lung cancer were recorded. Smoking status was identified as an effect modifier. Lung cancer incidence and mortality were significantly associated with PP only in non-smokers, respectively, HR=3.13 (95% CI 1.04 to 9.35) and HR=16.83 (95% CI 1.87 to 151.24) after adjustment for age, occupational asbestos exposure and smoking status.

Conclusions: ARDCO study was the first to study this association considering equal asbestos exposure, and more specifically, our study is the first to test smoking as an effect modifier, so comparison with scientific literature is difficult. Our results seem to consolidate the hypothesis that PP may be an independent risk factor for lung cancer but they must be interpreted with caution.

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Mesothelioma risk among those exposed to chrysotile asbestos only and mixtures that include amphibole: a case-control study in the USA, 1975-1980. J.Y.Y. Wong, C. Rice, A. Blair, et al. 2021;78(3):199-202. PubMed · Publisher · Free full text

Abstract

Objectives: Occupational asbestos exposure is causally linked to mesothelioma. However, whether exposure to only chrysotile asbestos is associated with mesothelioma risk, and the heterogeneity in risk by different fibre types/lengths remains unclear. We investigated whether mesothelioma risk differs among workers exposed to only chrysotile asbestos compared with chrysotile and ≥1 amphibole (ie, amosite, tremolite, anthophyllite and crocidolite) over the working lifetime.

Methods: We analysed next-of-kin interview data including occupational histories for 580 white men (176 cases and 404 controls) from a case-control study of mesothelioma conducted in the USA in 1975-1980. Asbestos exposure was determined by an occupational hygienist using a job-exposure matrix and exposure categories included chrysotile only and nine chrysotile-amphibole mixtures. Logistic regression models were used to estimate the ORs and 95% CIs of mesothelioma, comparing each asbestos category to the unexposed group, adjusted for age at death and data source. Analysis of contrasts was used to assess overall heterogeneity and pair-wise differences in risk.

Results: Exposure to long and short chrysotile only was associated with increased mesothelioma risk compared with the unexposed (OR=3.8 (95% CI 1.3 to 11.2)). The complex mixture of extra-long amosite, short and long chrysotile, tremolite and anthophyllite was associated with the highest risk (OR=12.8 (95% CI 4.1 to 40.2)). There was evidence for overall heterogeneity among the asbestos exposure categories (p heterogeneity=0.02). However, the lower risk observed for exposure to chrysotile only compared with the complex mixture was not significant (p difference=0.10).

Conclusions: Our findings suggest that policies aimed at regulating asbestos should target both pure chrysotile and mixtures that include amphibole.

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Survival of patients with asbestosis can be assessed by risk-predicting models. E. Keskitalo, J. Salonen, H. Vähänikkilä, et al. 2021;78(7):516-521. PubMed · Publisher

Abstract

Objectives: Our aim was to investigate the pulmonary function test (PFT) results of patients with asbestosis and determine whether baseline PFTs and the risk-predicting models such as gender, age and physiologic (GAP) variables model and composite physiologic index (CPI) would be useful in predicting survival in these patients.

Methods: Demographics and PFTs of 100 patients with asbestosis were evaluated. The survival difference between the GAP stages was determined with Kaplan-Meier survival curves with statistical significance analysed with log-rank test. The suitability of the risk-predicting models and baseline PFTs to predict the survival of patients was analysed with Cox regression.

Results: At baseline, the mean value of diffusion capacity for carbon monoxide (DLCO) was 65%; for forced vital capacity it was 81%, with restrictive lung function being the most common impairment. The median estimated survival of the patients was 124 months, that is, 171 months in GAP stage I, 50 months in stage II and 21 months in stage III (p<0.001). CPI, DLCO% predicted, age at baseline and GAP stage were significant predictors of mortality (all p values under 0.001).

Conclusions: GAP and CPI as well as baseline DLCO% predicted were significant parameters in the evaluation of the prognosis of the patients with asbestosis; they may be useful in clinical practice when considering treatment strategies of individual patients.

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Telomerase gene variants and telomere shortening in patients with silicosis or asbestosis. Y. Fan, C. Zheng, N. Wu, et al. 2021;78(5):342-348. PubMed · Publisher

Abstract

Objectives: Telomerase gene variants that lead to accelerated telomere shortening are linked to progressive-fibrosing interstitial lung diseases. However, little is known about their relationships with pneumoconiosis. This study aimed to identify TERT/TERC variants and leucocyte telomere lengths (LTL) in patients with silicosis or asbestosis.

Methods: In the present study, Sanger sequencing of TERT/TERC variants was performed in 193 Chinese Han patients with pneumoconiosis, including 109 with silicosis and 84 with asbestosis. Quantitative PCR was used to measure LTL in peripheral blood of the patients and 200 age and sex-matched healthy controls.

Results: In total, 7.3% patients with pneumoconiosis had 17 TERT/TERC variants. Among which 8.3% of patients with silicosis and 3.6% of patients with asbestosis had TERT variants, respectively. No TERC variants were detected in silicosis, whereas 3.6% of patients with asbestosis had TERC variants. Telomeres were significantly shorter in the patients with pneumoconiosis compared with healthy controls (p<0.001). No significant differences in LTL were found between TERT/TERC variant carriers and non-carriers. Exposure to silica dust was associated with the severity of pneumoconiosis after adjusting for covariates (OR 4.92, p=0.002). However, TERT/TERC variants and short telomeres were not associated with the severity of pneumoconiosis.

Conclusion: Telomerase gene variants and short telomeres may be identified in the patients with silicosis and asbestosis in response to the exposure to silica or asbestos dust but are not related to disease severity.

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'Compositional data analysis' by Barabesi and Sartorelli: Authors' response. R. Kaarteenaho, E. Keskitalo. 2020;77(5):351. Letter · Comment PubMed · Publisher
Author's response to 'Re: Exposure to asbestos and the risk of colorectal cancer mortality: a systematic review and meta-analysis by Kwak et al'. K. Kwak, D. Paek, K.E. Zoh. 2020;77(9):656-657. Letter · Comment PubMed · Publisher
Compositional data analysis. L. Barabesi, P. Sartorelli. 2020;77(5):352. Letter · Comment PubMed · Publisher
Global and regional burden of cancer in 2016 arising from occupational exposure to selected carcinogens: a systematic analysis for the Global Burden of Disease Study 2016. GBD 2016 Occupational Carcinogens Collaborators. 2020;77(3):151-159. PubMed · Publisher · Free full text

Abstract

Objectives: This study provides a detailed analysis of the global and regional burden of cancer due to occupational carcinogens from the Global Burden of Disease 2016 study.

Methods: The burden of cancer due to 14 International Agency for Research on Cancer Group 1 occupational carcinogens was estimated using the population attributable fraction, based on past population exposure prevalence and relative risks from the literature. The results were used to calculate attributable deaths and disability-adjusted life years (DALYs).

Results: There were an estimated 349 000 (95% Uncertainty Interval 269 000 to 427 000) deaths and 7.2 (5.8 to 8.6) million DALYs in 2016 due to exposure to the included occupational carcinogens-3.9% (3.2% to 4.6%) of all cancer deaths and 3.4% (2.7% to 4.0%) of all cancer DALYs; 79% of deaths were of males and 88% were of people aged 55 -79 years. Lung cancer accounted for 86% of the deaths, mesothelioma for 7.9% and laryngeal cancer for 2.1%. Asbestos was responsible for the largest number of deaths due to occupational carcinogens (63%); other important risk factors were secondhand smoke (14%), silica (14%) and diesel engine exhaust (5%). The highest mortality rates were in high-income regions, largely due to asbestos-related cancers, whereas in other regions cancer deaths from secondhand smoke, silica and diesel engine exhaust were more prominent. From 1990 to 2016, there was a decrease in the rate for deaths (-10%) and DALYs (-15%) due to exposure to occupational carcinogens.

Conclusions: Work-related carcinogens are responsible for considerable disease burden worldwide. The results provide guidance for prevention and control initiatives.

© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY. Published by BMJ.
Global and regional burden of disease and injury in 2016 arising from occupational exposures: a systematic analysis for the Global Burden of Disease Study 2016. GBD 2016 Occupational Risk Factors Collaborators. 2020;77(3):133-141. PubMed · Publisher · Free full text

Abstract

Objectives: This study provides an overview of the influence of occupational risk factors on the global burden of disease as estimated by the occupational component of the Global Burden of Disease (GBD) 2016 study.

Methods: The GBD 2016 study estimated the burden in terms of deaths and disability-adjusted life years (DALYs) arising from the effects of occupational risk factors (carcinogens; asthmagens; particulate matter, gases and fumes (PMGF); secondhand smoke (SHS); noise; ergonomic risk factors for low back pain; risk factors for injury). A population attributable fraction (PAF) approach was used for most risk factors.

Results: In 2016, globally, an estimated 1.53 (95% uncertainty interval 1.39-1.68) million deaths and 76.1 (66.3-86.3) million DALYs were attributable to the included occupational risk factors, accounting for 2.8% of deaths and 3.2% of DALYs from all causes. Most deaths were attributable to PMGF, carcinogens (particularly asbestos), injury risk factors and SHS. Most DALYs were attributable to injury risk factors and ergonomic exposures. Men and persons 55 years or older were most affected. PAFs ranged from 26.8% for low back pain from ergonomic risk factors and 19.6% for hearing loss from noise to 3.4% for carcinogens. DALYs per capita were highest in Oceania, Southeast Asia and Central sub-Saharan Africa. On a per capita basis, between 1990 and 2016 there was an overall decrease of about 31% in deaths and 25% in DALYs.

Conclusions: Occupational exposures continue to cause an important health burden worldwide, justifying the need for ongoing prevention and control initiatives.

© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY. Published by BMJ.
Mortality in a cohort of US firefighters from San Francisco, Chicago and Philadelphia: an update. L. Pinkerton, S.J. Bertke, J. Yiin, et al. 2020;77(2):84-93. PubMed · Publisher · Free full text

Abstract

Objectives: To update the mortality experience of a previously studied cohort of 29 992 US urban career firefighters compared with the US general population and examine exposure-response relationships within the cohort.

Methods: Vital status was updated through 2016 adding 7 years of follow-up. Cohort mortality compared with the US population was evaluated via life table analyses. Full risk-sets, matched on attained age, race, birthdate and fire department were created and analysed using the Cox proportional hazards regression to examine exposure-response associations between select mortality outcomes and exposure surrogates (exposed-days, fire-runs and fire-hours). Models were adjusted for a potential bias from healthy worker survivor effects by including a categorical variable for employment duration.

Results: Compared with the US population, mortality from all cancers, mesothelioma, non-Hodgkin's lymphoma (NHL) and cancers of the oesophagus, intestine, rectum, lung and kidney were modestly elevated. Positive exposure-response relationships were observed for deaths from lung cancer, leukaemia and chronic obstructive pulmonary disease (COPD).

Conclusions: This update confirms previous findings of excess mortality from all cancers and several site-specific cancers as well as positive exposure-response relations for lung cancer and leukaemia. New findings include excess NHL mortality compared with the general population and a positive exposure-response relationship for COPD. However, there was no evidence of an association between any quantitative exposure measure and NHL.

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Occupational lung disease: the need for a global surveillance system. K. Asanati, S.H. Al Jassasi, A. Sherafat, et al. 2020;77(7):506-507. Letter · Comment PubMed · Publisher
Re: Exposure to asbestos and the risk of colorectal cancer mortality: a systematic review and meta-analysis by Kwak et al. P. Boffetta. 2020;77(9):655. Letter · Comment PubMed · Publisher
Tobacco smoking among chrysotile asbestos workers in Asbest in the Russian Federation. A. Olsson, E.V. Kovalevskiy, M. Talibov, et al. 2020;77(9):623-627. PubMed · Publisher · Free full text

Abstract

Objectives: A historical cohort study of cancer mortality is being conducted among workers in a chrysotile mine and its enrichment factories in the town of Asbest, Russian Federation. Because individual-level information on tobacco use is not available for Asbest Chrysotile Cohort members, a cross-sectional survey of smoking behaviours was conducted among active and retired workers.

Methods: Self-administered questionnaires were completed by active workers during meetings organised by occupational safety personnel. Retired workers completed questionnaires during meetings of the Veterans Council or were interviewed via telephone or in person. Of the respondents, 46% could be linked to the Asbest Chrysotile Cohort. Among those, logistic regression models were used to assess associations between smoking and cumulative dust exposure.

Results: Among men, smoking prevalence was high and relatively consistent across birth decades (average, 66%), and was similar in workers across all levels of cumulative dust exposure (p trend, 0.44). Among women, the prevalence increased from <10% in those born before 1960 to 30% in those born after 1980, and smoking was associated with exposure to dust versus not exposed to dust (p value, 0.006), but did not vary appreciably across workers in different cumulative dust exposure categories (p trend, 0.29).

Conclusions: Our study suggests that cross-sectional surveys may be a useful tool for understanding the potential health impact from smoking in occupational cohorts, including possible confounding by smoking. This survey showed that adjustment at the age group level among women is needed to reduce residual confounding and account for smoking patterns, which have changed substantially over time.

© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.
Transplantation for work-related lung disease in the USA. D.J. Blackley, C.N. Halldin, J.W.A. Hayanga, et al. 2020;77(11):790-794. PubMed · Publisher · Free full text

Abstract

Objectives: Work-related lung diseases (WRLDs) are entirely preventable. To assess the impact of WRLDs on the US transplant system, we identified adult lung transplant recipients with a WRLD diagnosis specified at the time of transplant to describe demographic, payer and clinical characteristics of these patients and to assess post-transplant survival.

Methods: Using US registry data from 1991 to 2018, we identified lung transplant recipients with WRLDs including coal workers' pneumoconiosis, silicosis, asbestosis, metal pneumoconiosis and berylliosis.

Results: The frequency of WRLD-associated transplants has increased over time. Among 230 lung transplants for WRLD, a majority were performed since 2009; 79 were for coal workers' pneumoconiosis and 78 were for silicosis. Patients with coal workers' pneumoconiosis were predominantly from West Virginia (n=31), Kentucky (n=23) or Virginia (n=10). States with the highest number of patients with silicosis transplant were Pennsylvania (n=12) and West Virginia (n=8). Patients with metal pneumoconiosis and asbestosis had the lowest and highest mean age at transplant (48.8 and 62.1 years). Median post-transplant survival was 8.2 years for patients with asbestosis, 6.6 years for coal workers' pneumoconiosis and 7.8 years for silicosis. Risk of death among patients with silicosis, coal workers' pneumoconiosis and asbestosis did not differ when compared with patients with idiopathic pulmonary fibrosis.

Conclusions: Lung transplants for WRLDs are increasingly common, indicating a need for primary prevention and surveillance in high-risk occupations. Collection of patient occupational history by the registry could enhance case identification and inform prevention strategies.

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Welding and the risk of head and neck cancer: the ICARE study. C. Barul, M. Matrat, A. Auguste, et al. 2020;77(5):293-300. PubMed · Publisher

Abstract

Objective: To investigate the association between occupational exposure to welding and the risk of head and neck cancer in a large French population-based case-control study, the Investigation of occupational and environmental CAuses of REspiratory cancers study.

Methods: Analyses were restricted to men (2703 controls and 1588 cases of squamous-cell carcinoma of the oral cavity, oropharynx, hypopharynx and larynx). Welding activity and potential confounders were assessed by detailed questionnaires. ORs and CIs (95% CI) were estimated by unconditional logistic regression, adjusted for age, area of residence, tobacco smoking, alcohol consumption and occupational exposure to asbestos.

Results: Welding was associated with an increased risk of head and neck cancer overall (OR=1.31, 95% CI 1.03 to 1.67). The association was strongest for laryngeal cancer (OR=1.66, 95% CI 1.15 to 2.38) and the risk increased with the cumulative duration (p-trend <0.01) and the weighted duration (p-trend <0.01) of welding. A cumulative duration and a weighted duration of welding of more than 10 years were also associated with a significantly increased risk of oral cancer (OR=1.82, 95% CI 1.09 to 3.04; OR=2.10, 95% CI 0.99 to 4.45, respectively). A long duration of arc welding was associated with laryngeal cancer, whereas a long duration of spot welding was associated with oral cancer. Welding was not associated with the risk of oropharyngeal and hypopharyngeal cancer.

Conclusion: Our findings suggest that welding and several welding-related tasks increase the risk of laryngeal cancer and to a lesser extent oral cancer.

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2010s

Bronchoalveolar cell differential count and the number of asbestos bodies correlate with survival in patients with asbestosis. E. Keskitalo, L. Varis, R. Bloigu, et al. 2019;76(10):765-771. PubMed · Publisher

Abstract

Objectives: To determine cell differential counts and the number of asbestos bodies (ABs) in bronchoalveolar lavage (BAL) fluid obtained from patients with asbestosis, and to correlate the results with their survival.

Methods: The BAL cell differential counts and ABs from 91 patients with asbestosis were determined. The BAL cell differential counts were analysed in relation to smoking status. BAL cell differential counts and the number of ABs were correlated with the patients' survivals.

Results: A neutrophilic cell pattern was observed independently of smoking habits with both Papanicolau (8.4%) and May-Grunwald-Giemsa (6.5%) staining. Smoking and a high number of ABs (>2 AB/mL) were associated with high total cell counts and high macrophage and low lymphocyte differential counts. The median survival of the patients was 131.8 months. Shortened survival was associated with high numbers of ABs (78 vs 165 months; p=0.042) and low lymphocyte (77 vs 179 months; p=0.005), high neutrophil (102 vs 180 months; p=0.016) and high eosinophil (104 vs170 months; p=0.007) differential counts.

Conclusion: A neutrophilic cell pattern was evident in BAL from patients with asbestosis. Smoking and ABs both affected the total cell count and the macrophage and lymphocyte differential counts. Several BAL parameters associated with patient survival, suggesting that BAL cell count analyses could be used in the estimation of the prognosis of patients with asbestosis.

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Environmental asbestos exposure in childhood and risk of mesothelioma later in life: a long-term follow-up register-based cohort study. S.B. Dalsgaard, E.T. Würtz, J. Hansen, et al. 2019;76(6):407-413. PubMed · Publisher

Abstract

Objective: To examine the risk of malignant mesothelioma (MM) in former pupils who attended primary school near an asbestos cement plant.

Methods: A cohort of 12 111 former pupils, born 1940-1970, was established from individual historical records from four primary schools located at a distance of 100-750 m in the prevailing wind direction from an asbestos cement plant operating from 1928 to 1984 in Aalborg, Denmark. The school cohort and a comparison cohort consisting of 108 987 gender and 5-year frequency-matched subjects were followed up (2015) for MM in the Danish Cancer Registry. Using Cox regression, HRs were estimated for the incidence of MM. Adjustments for occupational and familial asbestos exposure were made with a job exposure matrix. An SIR analysis including latency periods testing the cancer incidence rate was performed with the comparison cohort as the reference rate.

Results: The median person-years of follow-up were 62.5 years in the school cohort and 62.2 years in the comparison cohort. There were 32 males and 6 females of the former pupils who developed MM during the follow-up: HRmale 7.01 (95% CI 4.24 to 11.57), HRfemale 7.43 (95% CI 2.50 to 22.13). Those who attended school 250 m north of the plant had the highest HR for MM, 10.65 (95% Cl 5.82 to 19.48). No significant trend between school distance and risk of MM was established (p=0.35).

Conclusion: Our results suggest that boys and girls who attended schools and lived in the neighbourhood of an asbestos cement plant later in life have a significantly increased risk of MM.

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Exposure to asbestos and the risk of colorectal cancer mortality: a systematic review and meta-analysis. K. Kwak, D. Paek, K.E. Zoh. 2019;76(11):861-871. Meta-analysis · Systematic review PubMed · Publisher

Abstract

Asbestos exposure is associated with mesothelioma and cancer of the lung, larynx and ovary. However, the association between asbestos exposure and colorectal cancer is controversial despite several systematic reviews of the literature, including a number of meta-analyses. We performed a systematic review and meta-analysis to evaluate quantitatively the association between exposure to asbestos and colorectal cancer. We searched for articles on occupational asbestos exposure and colorectal cancer in PubMed, EMBASE and Web of Science published before April 2018. In total, 44 articles were selected and 46 cohort studies were analysed. The overall pooled risk estimates and corresponding 95% CIs of the association between occupational asbestos exposure and colorectal cancer were calculated using a random-effects model. Subgroup analyses and sensitivity tests were also performed. There was a significantly increased risk of colorectal cancer mortality among workers exposed to asbestos occupationally, with an overall pooled SMR of 1.16 (95% CI: 1.05 to 1.29). The pooled SMR for colorectal cancer was elevated in studies in which the asbestos-associated risk of lung cancer was also elevated (1.43; 95% CI: 1.30 to 1.56). This implies that the risk of colorectal cancer mortality increases as the level of asbestos exposure rises. A sensitivity analysis showed robust results and there was no publication bias. Although the effect size was small and the heterogeneity among studies was large, our findings indicate that occupational exposure to asbestos is a risk factor for colorectal cancer.

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Mesothelioma mortality in Great Britain: how much longer will dockyards dominate?. C.J. Reynolds, C. Minelli, A. Darnton, et al. 2019;76(12):908-912. PubMed · Publisher

Abstract

Objectives: We aimed to investigate whether there has been a geographic shift in the distribution of mesothelioma deaths in Great Britain given the decline of shipbuilding and progressive exposure regulation.

Methods: We calculated age-adjusted mesothelioma mortality rates and estimated rate ratios for areas with and without a dockyard. We compared spatial autocorrelation statistics (Moran's I) for age-adjusted rates at local authority district level for 2002-2008 and 2009-2015. We measured the mean distance of the deceased's postcode to the nearest dockyard at district level and calculated the association of average distance to dockyard and district mesothelioma mortality using simple linear regression for men, for 2002-2008 and 2009-2015.

Results: District age-adjusted male mortality rates fell during 2002-2015 for 80 of 348 districts (23%), rose for 267 (77%) and were unchanged for one district; having one or more dockyards in a district was associated with rates falling (OR=2.43, 95% CI 1.22 to 4.82, p=0.02). The mortality rate ratio for men in districts with a dockyard, compared with those without a dockyard was 1.41 (95% CI 1.35 to 1.48, p<0.05) for 2002-2008 and 1.18 (95% CI 1.13 to 1.23, p<0.05) for 2009-2015. Spatial autocorrelation (measured by Moran's I) decreased from 0.317 (95% CI 0.316 to 0.319, p=0.001) to 0.312 (95% CI 0.310 to 0.314, p=0.001) for men and the coefficient of the association between distance to dockyard and district level age-adjusted male mortality (per million population) from -0.16 (95% CI -0.21 to -0.10, p<0.01) to -0.13 (95% CI -0.18 to -0.07, p<0.01) for men, when comparing 2002-2008 with 2009-2015.

Conclusion: For most districts age-adjusted mesothelioma mortality rates increased through 2002-2015 but the relative contribution from districts with a dockyard fell. Dockyards remain strongly spatially associated with mesothelioma mortality but the strength of this association appears to be falling and mesothelioma deaths are becoming more dispersed.

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Occupational and work-related respiratory disease attributed to cleaning products. M. Carder, M.J. Seed, A. Money, et al. 2019;76(8):530-536. PubMed · Publisher

Abstract

Objectives: Exposure to cleaning products has been associated with adverse respiratory outcomes. This study aimed to investigate the medically reported incidence, trends in incidence and occupational determinants of work-related respiratory disorders attributed to cleaning agents and to explore the role of 'Quantitative Structure Activity Relationships' (QSAR) in corroborating the identification of chemical respiratory sensitisers.

Methods: Respiratory diagnoses attributed to cleaning agents were extracted from The Health and Occupation Research (THOR) surveillance network, 1989-2017. Incidence, trends in incidence and incidence rate ratios by occupation were investigated. Agents were classified by chemical type and QSAR hazard indices were determined for specific organic chemicals.

Results: Approximately 6% (779 cases) of the (non-asbestos) THOR respiratory cases were attributed to cleaning agents. Diagnoses were predominantly asthma (58%) and inhalation accidents (27%) with frequently reported chemical categories being aldehydes (30%) and chlorine/its releasers (26%). No significant trend in asthma incidence (1999-2017) was observed (annual average change of -1.1% (95% CI -4.4 to 2.4)). This contrasted with a statistically significant annual decline in asthma incidence (-6.8% (95% CI -8.0 to -5.6)) for non-cleaning agents. There was a large variation in risk between occupations. 7 of the 15 organic chemicals specifically identified had a QSAR generated hazard index consistent with being a respiratory sensitiser.

Conclusion: Specific occupations appear to be at increased risk of adverse respiratory outcomes attributed to cleaning agents. While exposure to agents such as glutaraldehyde have been addressed, other exposures, such as to chlorine, remain important. Chemical features of the cleaning agents helped distinguish between sensitising and irritant agents.

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Occupational exposure to wood dust and risk of lung cancer: the ICARE study. M. Matrat, L. Radoï, J. Févotte, et al. 2019;76(12):901-907. PubMed · Publisher

Abstract

Objectives: In a previous analysis of data from a French population-based case-control study (the Investigation of occupational and environmental CAuses of REspiratory cancers (ICARE) study), 'having ever worked' in wood-related occupations was associated with excess lung cancer risk after adjusting for smoking but not for occupational factors. The present study aimed to investigate the relationship between lung cancer risk and wood dust exposure after adjusting for occupational exposures.

Methods: Data were obtained from 2276 cases and 2780 controls on smoking habits and lifelong occupational history, using a standardised questionnaire with a job-specific questionnaire for wood dust exposure. Logistic regression models were used to calculate ORs and 95% CIs adjusted for age, area of residence, tobacco smoking, the number of job periods and exposure to silica, asbestos and diesel motor exhaust (DME).

Results: No significant association was found between lung cancer and wood dust exposure after adjustment for smoking, asbestos, silica and DME exposures. The risk of lung cancer was slightly increased among those who were exposed to wood dust more than 10 years, and had over 40 years since the first exposure.

Conclusion: Our findings do not provide a strong support to the hypothesis that wood dust exposure is a risk factor for lung cancer. This study showed the importance of taking into account smoking and occupational coexposures in studies on lung cancer and wood dust exposure. Further studies evaluating the level and frequency of exposure during various tasks in woodwork are needed.

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Peritoneal mesothelioma and asbestos exposure: a population-based case-control study in Lombardy, Italy. D. Consonni, C. Calvi, S. De Matteis, et al. 2019;76(8):545-553. PubMed · Publisher · Free full text

Abstract

Objectives: Asbestos is the main risk factor for peritoneal mesothelioma (PeM). However, due to its rarity, PeM has rarely been investigated in community-based studies. We examined the association between asbestos exposure and PeM risk in a general population in Lombardy, Italy.

Methods: From the regional mesothelioma registry, we selected PeM cases diagnosed in 2000-2015. Population controls (matched by area, gender and age) came from two case-control studies in Lombardy on lung cancer (2002-2004) and pleural mesothelioma (2014). Assessment of exposure to asbestos was performed through a quantitative job-exposure matrix (SYN-JEM) and expert evaluation based on a standardised questionnaire. We calculated period-specific and gender-specific OR and 90% CI using conditional logistic regression adjusted for age, province of residence and education.

Results: We selected 68 cases and 2116 controls (2000-2007) and 159 cases and 205 controls (2008-2015). The ORs for ever asbestos exposure (expert-based, 2008-2015 only) were 5.78 (90% CI 3.03 to 11.0) in men and 8.00 (2.56 to 25.0) in women; the ORs for definite occupational exposure were 12.3 (5.62 to 26.7) in men and 14.3 (3.16 to 65.0) in women. The ORs for ever versus never occupational asbestos exposure based on SYN-JEM (both periods) were 2.05 (90% CI 1.39 to 3.01) in men and 1.62 (0.79 to 3.27) in women. In men, clear positive associations were found for duration, cumulative exposure (OR 1.33 (1.19 to 1.48) per fibres/mL-years) and latency.

Conclusions: Using two different methods of exposure assessment we provided evidence of a clear association between asbestos exposure and PeM risk in the general population.

© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.
Response to letter by Farioli et al. A. Reid, P. Franklin, G. Berry, et al. 2019;76(5):356. Letter · Comment PubMed · Publisher
Response to: 'Are children more vulnerable to mesothelioma than adults? A comparison of mesothelioma risk among children and adults exposed non-occupationally to blue asbestos at Wittenoom' by Reid et al. A. Farioli, P. Boffetta, S. Curti, et al. 2019;76(5):355. Letter · Comment PubMed · Publisher
Role of asbestos clearance in explaining long-term risk of pleural and peritoneal cancer: a pooled analysis of cohort studies. F. Barone-Adesi, D. Ferrante, E. Chellini, et al. 2019;76(9):611-616. PubMed · Publisher

Abstract

Objectives: Models based on the multistage theory of cancer predict that rates of malignant mesothelioma continuously increase with time since first exposure (TSFE) to asbestos, even after the end of external exposure. However, recent epidemiological studies suggest that mesothelioma rates level off many years after first exposure to asbestos. A gradual clearance of asbestos from the lungs has been suggested as a possible explanation for this phenomenon. We analysed long-term trends of pleural and peritoneal cancer mortality in subjects exposed to asbestos to evaluate whether such trends were consistent with the clearance hypothesis.

Methods: We used data from a pool of 43 Italian asbestos cohorts (51 801 subjects). The role of asbestos clearance was explored using the traditional mesothelioma multistage model, generalised to include a term representing elimination of fibres over time.

Results: Rates of pleural cancer increased until 40 years of TSFE, but remained stable thereafter. On the other hand, we observed a monotonic increase of peritoneal cancer with TSFE. The model taking into account asbestos clearance fitted the data better than the traditional one for pleural (p=0.004) but not for peritoneal (p=0.09) cancer.

Conclusions: Rates of pleural cancer do not increase indefinitely after the exposure to asbestos, but eventually reach a plateau. This trend is well described by a model accounting for a gradual elimination of the asbestos fibres. These results are relevant for the prediction of future rates of mesothelioma and in asbestos litigations.

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Welding fumes and lung cancer: a meta-analysis of case-control and cohort studies. M.K. Honaryar, R.M. Lunn, D. Luce, et al. 2019;76(6):422-431. Meta-analysis · Systematic review PubMed · Publisher · Free full text

Abstract

Background: An estimated 110 million workers are exposed to welding fumes worldwide. Welding fumes are classified by the International Agency for Research on Cancer as carcinogenic to humans (group 1), based on sufficient evidence of lung cancer from epidemiological studies.

Objective: To conduct a meta-analysis of case-control and cohort studies on welding or exposure to welding fumes and risk of lung cancer, accounting for confounding by exposure to asbestos and tobacco smoking.

Methods: The literature was searched comprehensively in PubMed, reference lists of relevant publications and additional databases. Overlapping populations were removed. Meta-relative risks (mRRs) were calculated using random effects models. Publication bias was assessed using funnel plot, Eggers's test and Begg's test.

Results: Forty-five studies met the inclusion criteria (20 case-control, 25 cohort/nested case-control), which reduced to 37 when overlapping study populations were removed. For 'ever' compared with 'never' being a welder or exposed to welding fumes, mRRs and 95% CIs were 1.29 (1.20 to 1.39; I2=26.4%; 22 studies) for cohort studies, 1.87 (1.53 to 2.29; I2=44.1%; 15 studies) for case-control studies and 1.17 (1.04 to 1.38; I2=41.2%) for 8 case-control studies that adjusted for smoking and asbestos exposure. The mRRs were 1.32 (95% CI 1.20 to 1.45; I2=6.3%; 15 studies) among 'shipyard welders', 1.44 (95% CI 1.07 to 1.95; I2=35.8%; 3 studies) for 'mild steel welders' and 1.38 (95% CI 0.89 to 2.13; I2=68.1%; 5 studies) among 'stainless steel welders'. Increased risks persisted regardless of time period, geographic location, study design, occupational setting, exposure assessment method and histological subtype.

Conclusions: These results support the conclusion that exposure to welding fumes increases the risk of lung cancer, regardless of the type of steel welded, the welding method (arc vs gas welding) and independent of exposure to asbestos or tobacco smoking.

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Are children more vulnerable to mesothelioma than adults? A comparison of mesothelioma risk among children and adults exposed non-occupationally to blue asbestos at Wittenoom. A. Reid, P. Franklin, G. Berry, et al. 2018;75(12):898-903. PubMed · Publisher

Abstract

Objectives: The presence of asbestos in public buildings is a legacy of past asbestos use in many developed countries. Of particular concern is the amount and current condition in schools and the vulnerability of children to mesothelioma. Our aim was to compare the risk of mesothelioma between those exposed to blue asbestos as children and as adults at Wittenoom.

Methods: Public sources were used to establish the Wittenoom residents' cohort. Mesothelioma incidence rates per 100 000 person-years at risk were derived for those first exposed to asbestos at Wittenoom as children (<15 years) or adults separately. Proportional hazards survival models examined the slope of the exposure-response relationship between asbestos exposure and incidence of mesothelioma in different sex and age groups.

Results: The mesothelioma rate was lower among those first exposed as children (76.8 per 100 000) than those first exposed as adults (121.3 per 100 000). Adjusting for cumulative exposure to asbestos and sex, those exposed as adults had a greater risk of mesothelioma (adjusted HR 2.5, 95% CI 1.7 to 3.7). The slope of the exposure-response relationship did not differ between those exposed as children and those exposed as adults.

Conclusion: We found no greater susceptibility to mesothelioma among those first exposed to asbestos as children than those first exposed as adults. However, given the long latency of mesothelioma, and the greater years of life yet to be lived by the Wittenoom children, it is likely that there will be more cases of mesothelioma in the future among those first exposed as children.

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Author reply: 'Response to: Pleural abnormalities in the Framingham Heart Study: prevalence and CT image features' by Araki et al. T. Araki, G.M. Hunninghake, D.C. Christiani, et al. 2018;75(1):77-78. Letter · Comment PubMed · Publisher
Cancer incidence among merchant seafarers: an extended follow-up of a Danish cohort. K. Ugelvig Petersen, J. Volk, L. Kaerlev, et al. 2018;75(8):582-585. PubMed · Publisher

Abstract

Objectives: While maritime safety generally has improved dramatically over the last century, modern seafarers are still faced with numerous occupational hazards potentially affecting their risk of chronic diseases such as cancer. The aim of this study is to offer updated information on the incidence of specific cancers among both male and female seafarers.

Methods: Using records from the Danish Seafarer Registry, all seafarers employed on Danish ships during 1986-1999 were identified, resulting in a cohort of 33 084 men and 11 209 women. Information on vital status and cancer was linked to each member of the cohort from the Danish Civil Registration System and the Danish Cancer Registry using the unique Danish personal identification number. SIRs were estimated for specific cancers using national rates.

Results: The overall incidence of cancer was increased for both male and female seafarers (SIR 1.19, 95% CI 1.15 to 1.23, and SIR 1.14, 95% CI 1.07 to 1.22) compared with the general population. This excess was primarily driven by increases in gastrointestinal, respiratory and genitourinary cancers. In addition, male seafarers working in areas with asbestos exposure showed significantly increased risk of mesothelioma. Finally, the male seafarers had an increased risk of lip cancer.

Conclusions: The majority of cancers among seafarers continue to be lifestyle-related. However, occupational exposure to asbestos and ultraviolet radiation seems to affect the cancer pattern among the male seafarers as well.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Dose-time response association between occupational asbestos exposure and pleural mesothelioma: authors' response. A. Lacourt, E. Leveque, M. Goldberg, et al. 2018;75(2):161-162. Letter · Comment PubMed · Publisher

Summary

In this letter, the authors replied to Boffetta et al's comments on their French case-control study of occupational asbestos exposure and pleural mesothelioma. They clarified its design. The 1196 cases came from two sources: 496 from a hospital-based case-control study conducted in 1987–1993 in five French regions, and 700 incident cases identified by the French National Mesothelioma Surveillance Programme in 1998–2006. Together they covered 42 departments across metropolitan France, and the distribution of occupational asbestos exposure was similar in the two case sources. The 2369 controls came from a 2007 representative national sample (751) and from 15 epidemiological studies conducted in 1984–2000 (1618). They were frequency matched to cases on birth year, and analyses were adjusted for age. The authors acknowledged that controls recruited in 2007 may not represent the source population of earlier cases, and that questionnaires differed across studies. They stated that only birth date, index date and job history were used, and that exposure was assessed with one job exposure matrix. To test robustness, they reanalysed a single French population-based case-control study (1998–2005) of 371 cases and 732 matched population controls, using the same matrix and statistical method. Results were similar, with much wider confidence intervals. Exposure intensity received more than 35 years before diagnosis contributed most to risk, and recent intensity had a non-null weight despite a very large confidence interval.

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Letter concerning: 'Response to: 'The epidemiology of malignant mesothelioma in women: gender differences and modalities of asbestos exposure' by Marinaccio et al'. A. Marinaccio, M. Corfiati, A. Binazzi, et al. 2018;75(11):844-845. Letter · Comment PubMed · Publisher
Migration and work in postwar Australia: mortality profile comparisons between Australian and Italian workers exposed to blue asbestos at Wittenoom. A. Reid, E. Merler, S. Peters, et al. 2018;75(1):29-36. PubMed · Publisher

Abstract

Objectives: Three hundred and thirty thousand Italians arrived in Australia between 1945 and 1966, many on assisted passage schemes where the worker agreed to a 2-year unskilled employment contract. Italians were the largest of 52 migrant groups employed at the Wittenoom blue asbestos mining and milling operation. We compare mortality from asbestos-related diseases among Italian and Australian workers employed at Wittenoom.

Methods: A cohort of 6500 male workers was established from employment records and followed up at state and national mortality and cancer registries. SMRs were calculated to compare mortality with the Western Australian male population. Time-varying Cox proportional hazards models compared the risk of mesothelioma between Australian and Italian workers.

Results: 1031 Italians and 3465 Australians worked at Wittenoom between 1943 and 1966. Duration of employment was longer for the Italian workers, although the concentration of exposure was similar. The mesothelioma mortality rate per 100 000 was higher in Italians (184, 95% CI 148 to 229) than Australians (128, 95% CI 111 to 149). The risk of mesothelioma was greater than twofold (HR 2.27, 95% CI 1.43 to 3.60) in Italians at the lowest asbestos exposure category (<10 fibre years/per mL).

Conclusions: A hierarchy in migration, isolation and a shortage of workers led to Italians at Wittenoom incurring higher cumulative exposure to blue asbestos and subsequently a greater rate of malignant mesothelioma than Australian workers.

Impact: Poor working conditions and disparities between native and foreign-born workers has had a detrimental and differential impact on the long-term health of the workforce.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Occupational exposure to asbestos and risk of cholangiocarcinoma: a population-based case-control study in four Nordic countries. A. Farioli, K. Straif, G. Brandi, et al. 2018;75(3):191-198. PubMed · Publisher · Free full text

Abstract

Objectives: To assess the association between occupational exposure to asbestos and the risk of cholangiocarcinoma (CC).

Methods: We conducted a case-control study nested in the Nordic Occupational Cancer (NOCCA) cohort. We studied 1458 intrahepatic CC (ICC) and 3972 extrahepatic CC (ECC) cases occurring among subjects born in 1920 or later in Finland, Iceland, Norway and Sweden. Each case was individually matched by birth year, gender and country to five population controls. The cumulative exposure to asbestos (measured in fibres (f)/ml × years) was assessed by applying the NOCCA job-exposure matrix to data on occupations collected during national population censuses (conducted in 1960, 1970, 1980/81 and 1990). Odds ratios (OR) and 95% CI were estimated using conditional logistic regression models adjusted by printing industry work.

Results: We observed an increasing risk of ICC with cumulative exposure to asbestos: never exposed, OR 1.0 (reference category); 0.1-4.9 f/mL × years, OR 1.1 (95% CI 0.9 to 1.3); 5.0-9.9 f/mL × years, OR 1.3 (95% CI 0.9 to 2.1); 10.0-14.9 f/mL × years, OR 1.6 (95% CI 1.0 to 2.5); ≥15.0 f/mL × years, OR 1.7 (95% CI 1.1 to 2.6). We did not observe an association between cumulative asbestos exposure and ECC.

Conclusions: Our study provides evidence that exposure to asbestos might be a risk factor for ICC. Our findings also suggest that the association between ECC and asbestos is null or weaker than that observed for ICC. Further studies based on large industrial cohorts of asbestos workers and possibly accounting for personal characteristics and clinical history are needed.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Occupational exposures and cancer: a review of agents and relative risk estimates. C. Marant Micallef, K.D. Shield, I. Baldi, et al. 2018;75(8):604-614. PubMed · Publisher

Abstract

Objectives: The contribution of occupational exposures to the cancer burden can be estimated using population-attributable fractions, which is of great importance for policy making. This paper reviews occupational carcinogens, and presents the most relevant risk relations to cancer in high-income countries using France as an example, to provide a framework for national estimation of cancer burden attributable to occupational exposure.

Methods: Occupational exposures that should be included in cancer burden studies were evaluated using multiple criteria: classified as carcinogenic or probably carcinogenic by the International Agency for Research on Cancer (IARC) Monographs volumes 1-114, being a primary occupational exposure, historical and current presence of the exposure in France and the availability of exposure and risk relation data. Relative risk estimates were obtained from published systematic reviews and from the IARC Monographs.

Results: Of the 118 group 1 and 75 group 2A carcinogens, 37 exposures and 73 exposure-cancer site pairs were relevant. Lung cancer was associated with the most occupational carcinogenic exposures (namely, 18), followed by bladder cancer and non-Hodgkin's lymphoma. Ionising radiation was associated with the highest number of cancer sites (namely, 20), followed by asbestos and working in the rubber manufacturing industry. Asbestos, bis(chloromethyl)ether, nickel and wood dust had the strongest effect on cancer, with relative risks above 5.

Conclusions: A large number of occupational exposures continues to impact the burden of cancer in high-income countries such as France. Information on types of exposures, affected jobs, industries and cancer sites affected is key for prioritising policy and prevention initiatives.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Reanalysis of non-occupational exposure to asbestos and the risk of pleural mesothelioma. M.M. Finkelstein. 2018;75(6):472-473. Letter · Comment PubMed · Publisher
Response to: 'Dose-time-response association between occupational asbestos exposure and pleural mesothelioma' by Lacourt et al. P. Boffetta, E. Pira, C. Romano, et al. 2018;75(2):160. Letter · Comment PubMed · Publisher
Response to: 'Pleural abnormalities in the Framingham Heart Study: prevalence and CT image features' by Araki et al. A. Franzblau, V.C. Antao, G. Pinheiro, et al. 2018;75(1):77. Letter · Comment PubMed · Publisher · Free full text
Response to: 'Reanalysis of non-occupational exposure to asbestos and the risk of pleural mesothelioma' by Finkelstein. G.M. Marsh, A.S. Riordan, K.A. Keeton, et al. 2018;75(6):473-474. Letter · Comment PubMed · Publisher
Response to: 'The epidemiology of malignant mesothelioma in women: gender differences and modalities of asbestos exposure' by Marinaccio et al. M.M. Finkelstein. 2018;75(11):844. Letter · Comment PubMed · Publisher
The epidemiology of malignant mesothelioma in women: gender differences and modalities of asbestos exposure. A. Marinaccio, M. Corfiati, A. Binazzi, et al. 2018;75(4):254-262. PubMed · Publisher · Free full text

Abstract

Introduction: The epidemiology of gender differences for mesothelioma incidence has been rarely discussed in national case lists. In Italy an epidemiological surveillance system (ReNaM) is working by the means of a national register.

Methods: Incident malignant mesothelioma (MM) cases in the period 1993 to 2012 were retrieved from ReNaM. Gender ratio by age class, period of diagnosis, diagnostic certainty, morphology and modalities of asbestos exposure has been analysed using exact tests for proportion. Economic activity sectors, jobs and territorial distribution of mesothelioma cases in women have been described and discussed. To perform international comparative analyses, the gender ratio of mesothelioma deaths was calculated by country from the WHO database and the correlation with the mortality rates estimated.

Results: In the period of study a case list of 21 463 MMs has been registered and the modalities of asbestos exposure have been investigated for 16 458 (76.7%) of them. The gender ratio (F/M) was 0.38 and 0.70 (0.14 and 0.30 for occupationally exposed subjects only) for pleural and peritoneal cases respectively. Occupational exposures for female MM cases occurred in the chemical and plastic industry, and mainly in the non-asbestos textile sector. Gender ratio proved to be inversely correlated with mortality rate among countries.

Conclusions: The consistent proportion of mesothelioma cases in women in Italy is mainly due to the relevant role of non-occupational asbestos exposures and the historical presence of the female workforce in several industrial settings. Enhancing the awareness of mesothelioma aetiology in women could support the effectiveness of welfare system and prevention policies.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
The INTEROCC case-control study: risk of meningioma and occupational exposure to selected combustion products, dusts and other chemical agents. D.M. McElvenny, M. van Tongeren, M.C. Turner, et al. 2018;75(1):12-22. PubMed · Publisher

Abstract

Background: Little is known about occupational risk factors for meningioma.

Objectives: To study whether risk of meningioma is associated with several occupational exposures, including selected combustion products, dusts and other chemical agents.

Methods: The INTEROCC study was an international case-control study of brain cancer conducted in seven countries. Data collection by interview included lifetime occupational histories. A job exposure matrix was used to derive estimates of exposure for the 12 agents. ORs for ever versus never exposed and for exposure-response using duration of exposure and cumulative exposure were derived using conditional logistic regression stratified by sex, age group, country/region, adjusted for education.

Results: These analyses included 1906 cases and 5565 controls. For 11 of the 12 agents, no excess risk was found for ever exposed. For ever exposure to oil mists, an elevated OR of 1.57 (95% CI 1.10 to 2.22, 51 exposed cases) was found. Statistically significant exposure-response relationships were observed with cumulative exposure (p=0.01) and duration of exposure (p=0.04). Among women, there were also significant trends for cumulative and duration of exposure to asbestos and excesses in the highest exposure categories for formaldehyde.

Conclusions: Most agents examined did not provoke excess risks of meningioma. The main finding from this study is that it is the first study to identify a statistical association between exposure to oil mists and meningioma. This may be a chance finding or could be due to confounding with iron exposure and further research is required to understand whether the relationship is causal.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Time-dependent effect of intensity of smoking and of occupational exposure to asbestos on the risk of lung cancer: results from the ICARE case-control study. E. Lévêque, A. Lacourt, D. Luce, et al. 2018;75(8):586-592. PubMed · Publisher

Abstract

Objective: To estimate the impact of intensity of both smoking and occupational exposure to asbestos on the risk of lung cancer throughout the whole exposure history.

Methods: Data on 2026 male cases and 2610 male controls came from the French ICARE (Investigation of occupational and environmental causes of respiratory cancers) population-based, case-control study. Lifetime smoking history and occupational history were collected from standardised questionnaires and face-to-face interviews. Occupational exposure to asbestos was assessed using a job exposure matrix. The effects of annual average daily intensity of smoking (reported average number of cigarettes smoked per day) and asbestos exposure (estimated average daily air concentration of asbestos fibres at work) were estimated using a flexible weighted cumulative index of exposure in logistic regression models.

Results: Intensity of smoking in the 10 years preceding diagnosis had a much stronger association with the risk of lung cancer than more distant intensity. By contrast, intensity of asbestos exposure that occurred more than 40 years before diagnosis had a stronger association with the risk of lung cancer than more recent intensity, even if intensity in the 10 years preceding diagnosis also had a significant effect.

Conclusion: Our results illustrate the dynamic of the effect of intensity of both smoking and occupational exposure to asbestos on the risk of lung cancer. They confirm that the timing of exposure plays an important role, and suggest that standard analytical methods assuming equal weights of intensity over the whole exposure history may be questionable.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Asbestos bodies in bronchoalveolar lavage in the 21st century: a time-trend analysis in a clinical population. V. Nuyts, H. Vanhooren, S. Begyn, et al. 2017;74(1):59-65. PubMed · Publisher

Abstract

Objectives: Asbestos bodies (AB) in bronchoalveolar lavage (BAL) can be detected by light microscopy and their concentration is indicative of past cumulative asbestos exposure. We assessed clinical and exposure characteristics, as well as possible time trends, among patients in whom AB had been quantified in BAL.

Methods: BAL samples obtained from 578 participants between January 1997 and December 2014 were available for analysis. The processing of samples and the microscopic analysis were performed by a single expert and 76% of samples came from a single tertiary care hospital, allowing clinical and exposure data to be extracted from patient files.

Results: The study population (95% males) had a mean age of 62.5 (±12.4) years. AB were detected in 55.2% of the samples, giving a median concentration of 0.5 AB/mL (95th centile: 23.6 AB/mL; highest value: 164.5 AB/mL). The AB concentration exceeded 1 AB/mL in 39.4% and 5 AB/mL in 17.8%. A significant decrease from a geometric mean of 0.93 AB/mL in 1997 to 0.2 AB/mL in 2014 was apparent. High AB concentrations generally corresponded with occupations with (presumed) high asbestos exposure. AB concentrations were higher among patients with asbestosis and pleural plaques, when compared with other disease groups. Nevertheless, a substantial proportion of participants with likely exposure to asbestos did not exhibit high AB counts.

Conclusions: This retrospective study of a large clinical population supports the value of counting AB in BAL as a complementary approach to assess past exposure to asbestos.

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Data on mesothelioma mortality: a powerful tool for preventing asbestos-related disease. P.J. Landrigan. 2017;74(12):849-850. Editorial PubMed · Publisher

Summary

In this commentary, the author discussed a study by Odgerel and colleagues that estimated the annual global number of deaths from malignant mesothelioma, and argued for a worldwide asbestos ban. He stated that asbestos had caused over 200 000 deaths in the USA and 400 000 in Europe, and an estimated 180 000 deaths worldwide each year. He reported that two million tons were produced worldwide in 2013, that 55 countries had eliminated all import and use, and that the USA had sharply curtailed but not banned asbestos. He stated that bans typically produce decreases in asbestos-related mortality after 20–30 years. He summarised the Odgerel study. Using the WHO Mortality Database and US Geological Survey consumption data for the world's 230 countries, the investigators extrapolated from countries with high-quality reported data to countries not reporting mesothelioma deaths. They adjusted these estimates for cumulative and per capita asbestos consumption. The 59 reporting countries recorded 15 011 mesothelioma deaths annually in each of the past 3 years, and the investigators calculated that 38 400 mesothelioma deaths occur globally each year. This figure was within the range of earlier estimates but higher than the Global Burden of Disease estimate. The commentator described the estimates as highly credible and based on a transparent, replicable method. He concluded that no country is immune from asbestos-related disease and that a complete ban on all production, importation, processing and use of all forms of asbestos is the only effective way to prevent asbestos-related disease.

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Dose-time-response association between occupational asbestos exposure and pleural mesothelioma. A. Lacourt, E. Lévêque, E. Guichard, et al. 2017;74(9):691-697. PubMed · Publisher

Abstract

Objectives: Early occupational exposure to asbestos has been shown to be associated with an increased risk of pleural mesothelioma (PM), which suggests that the timing of exposure might play a role in the dose-response relationship. However, none studies has evaluated the relative impact of increasing the annual intensity of occupational exposure to asbestos at each time of the whole exposure history. Yet such evaluation would allow the comparison of the risks of PM associated with different longitudinal profiles of occupational exposure to asbestos. Our objective was to estimate the time-dependent relative impact of asbestos exposure intensity over the whole occupational history and to compare the resulting estimated risks of PM associated with different profiles of exposure, using data from a large French case-control study.

Methods: This study included 1196 male cases recruited in 1987-2006 and 2369 matched controls on birth year. Occupational exposure to asbestos was assessed using a job exposure matrix and represented in logistic regression models using a flexible weighted cumulative index of exposure.

Results: Due to much stronger weights of early doses of asbestos exposure, subjects who accumulated 20 fibres/mL over their entire job history with high doses during the first years and low doses thereafter were at higher risk of PM than those who accumulated most of the doses later (OR=2.37 (95% CI 2.01 to 2.87)).

Conclusion: This study provides new insights on the dose-time-response relationship between occupational asbestos and PM and illustrates the importance of considering timing of exposure in its association with cancer risk.

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Estimation of the global burden of mesothelioma deaths from incomplete national mortality data. C.O. Odgerel, K. Takahashi, T. Sorahan, et al. 2017;74(12):851-858. PubMed · Publisher · Free full text

Abstract

Background: Mesothelioma is increasingly recognised as a global health issue and the assessment of its global burden is warranted.

Objectives: To descriptively analyse national mortality data and to use reported and estimated data to calculate the global burden of mesothelioma deaths.

Methods: For the study period of 1994 to 2014, we grouped 230 countries into 59 countries with quality mesothelioma mortality data suitable to be used for reference rates, 45 countries with poor quality data and 126 countries with no data, based on the availability of data in the WHO Mortality Database. To estimate global deaths, we extrapolated the gender-specific and age-specific mortality rates of the countries with quality data to all other countries.

Results: The global numbers and rates of mesothelioma deaths have increased over time. The 59 countries with quality data recorded 15 011 mesothelioma deaths per year over the 3 most recent years with available data (equivalent to 9.9 deaths per million per year). From these reference data, we extrapolated the global mesothelioma deaths to be 38 400 per year, based on extrapolations for asbestos use.

Conclusions: Although the validity of our extrapolation method depends on the adequate identification of quality mesothelioma data and appropriate adjustment for other variables, our estimates can be updated, refined and verified because they are based on commonly accessible data and are derived using a straightforward algorithm. Our estimates are within the range of previously reported values but higher than the most recently reported values.

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Italian pool of asbestos workers cohorts: mortality trends of asbestos-related neoplasms after long time since first exposure. D. Ferrante, E. Chellini, E. Merler, et al. 2017;74(12):887-898. PubMed · Publisher

Abstract

Objective: Asbestos is a known human carcinogen, with evidence for malignant mesothelioma (MM), cancers of lung, ovary, larynx and possibly other organs. MM rates are predicted to increase with a power of time since first exposure (TSFE), but the possible long-term attenuation of the trend is debated. The asbestos ban enforced in Italy in 1992 gives an opportunity to measure long-term cancer risk in formerly exposed workers.

Methods: Pool of 43 previously studied Italian asbestos cohorts (asbestos cement, rolling stock, shipbuilding), with mortality follow-up updated to 2010. SMRs were computed for the 1970â€"2010 period, for the major causes, with consideration of duration and TSFE, using reference rates by age, sex, region and calendar period.

Results: The study included 51 801 subjects (5741 women): 55.9% alive, 42.6% died (cause known for 95%) and 1.5% lost to follow-up. Mortality was significantly increased for all deaths (SMR: men: 1.05, 95% CI 1.03 to 1.06; women: 1.17, 95% CI to 1.12 to 1.22), all malignancies combined (SMR: men: 1.17, 95% CI to 1.14 to 1.20; women: 1.33, 95% CI 1.24 to 1.43), pleural and peritoneal malignancies (SMR: men: 13.28 and 4.77, 95% CI 12.24 to 14.37 and 4.00 to 5.64; women: 28.44 and 6.75, 95% CI 23.83 to 33.69 and 4.70 to 9.39), lung (SMR: men: 1.26, 95% CI 1.21 to 1.31; women: 1.43, 95% CI 1.13 to 1.78) and ovarian cancer (SMR=1.38, 95% CI 1.00 to 1.87) and asbestosis (SMR: men: 300.7, 95% CI 270.7 to 333.2; women: 389.6, 95% CI 290.1 to 512.3). Pleural cancer rate increased during the first 40 years of TSFE and reached a plateau after.

Discussion: The study confirmed the increased risk for cancer of the lung, ovary, pleura and peritoneum but not of the larynx and the digestive tract. Pleural cancer mortality reached a plateau at long TSFE, coherently with recent reports.

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Mesothelin promoter variants are associated with increased soluble mesothelin-related peptide levels in asbestos-exposed individuals. C. De Santi, P. Pucci, A. Bonotti, et al. 2017;74(6):456-463. PubMed · Publisher

Abstract

Background: Soluble mesothelin-related peptide (SMRP) is a promising diagnostic biomarker for malignant pleural mesothelioma (MPM), but various confounders hinder its usefulness in surveillance programmes. We previously showed that a single nucleotide polymorphism (SNP) within the 3'untranslated region (3'UTR) of the mesothelin (MSLN) gene could affect the levels of SMRP.

Objectives: To focus on SNPs located within MSLN promoter as possible critical genetic variables in determining SMRP levels.

Methods: The association between SMRP and SNPs was tested in 689 non-MPM subjects and 70 patients with MPM. Reporter plasmids carrying the four most common haplotypes were compared in a dual luciferase assay, and in silico analyses were performed to investigate the putative biological role of the SNPs.

Results: We found a strong association between serum SMRP and variant alleles of rs3764247, rs3764246 (in strong linkage disequilibrium with rs2235504) and rs2235503 in non-MPM subjects. Inclusion of the genotype information led to an increase in SMRP specificity from 79.9% to 85.5%. Although not statistically significant, the group with MPM showed the same trend of association. According to the in vitro luciferase study, rs3764247 itself had a functional role. In silico approaches showed that the binding sites for transcription factors such as Staf and ZNF143 could be affected by this SNP. The other SNPs were shown to interact with each other in a more complex way.

Conclusions: These data support the suggestion that SMRP performance is affected by individual (ie, genetic) variables and that MSLN expression is influenced by SNPs located within the promoter regulatory region.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Mortality from cancer and other causes among Italian chrysotile asbestos miners. E. Pira, C. Romano, F. Donato, et al. 2017;74(8):558-563. PubMed · Publisher

Abstract

Objective: To investigate the long-term mortality of a cohort of Italian asbestos miners.

Methods: The cohort included 1056 men employed in a chrysotile mine between 1930 and 1990, who were followed up during 1946-2014, for a total of 37 471 person-years of observation. Expected deaths and SMRs were computed using national and local (after 1980, when available) reference.

Results: A total of 294 (27.8%) subjects were alive and at the end of follow-up, 722 (68.4%) were dead and 40 (3.8%) were lost to follow-up. The SMR for overall mortality was 1.35 (95%CI 1.25 to 1.45). The SMR for pleural cancer, based on seven observed deaths, was 5.54 (95% CI 2.22 to 11.4) and related to time since first exposure, but not to duration of employment, cumulative exposure or time since last exposure. The SMR for lung cancer was 1.16 (95% CI 0.87 to 1.52; 53 observed deaths), with no excess among workers with cumulative exposure below 100 fibre/mL-years (SMR 0.82; 95% CI 0.44 to 1.40).

Conclusions: The update of the follow-up of this cohort confirmed an increased mortality from pleural cancer mortality in miners exposed to chrysotile and a lack of significant increase in lung cancer mortality.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Non-occupational exposure to asbestos and risk of pleural mesothelioma: review and meta-analysis. G.M. Marsh, A.S. Riordan, K.A. Keeton, et al. 2017;74(11):838-846. Meta-analysis · Review PubMed · Publisher

Abstract

Objective: To conduct an updated literature review and meta-analysis of studies of pleural malignant mesothelioma (PMM) risk among persons exposed to asbestos non-occupationally (household and neighbourhood).

Methods: We performed a literature search for articles available in the National Center for Biotechnology Information's PubMed database published between 1967 and 2016. Meta-analyses were conducted to calculate pooled PMM risk estimates, stratifying for household or neighbourhood exposure to asbestos and/or predominant asbestos fibre type (chrysotile, amphibole or mixed).

Results: Eighteen studies in 12 countries comprising 665 cases met the meta-analysis inclusion criteria. We identified 13 estimates of PMM risk from neighbourhood exposures, 10 from household and one from mixed exposure, and combined the estimates using random-effects models. The overall meta-relative risk (meta-RR) was 5.9 (95% CI 4.4 to 8.7). The meta-RRs for household and neighbourhood exposures were 5.4 (95% CI 2.6 to 11.2) and 6.9 (95% CI 4.2 to 11.4), respectively. We observed trends in risk in relation to fibre type for both household and neighbourhood studies. For chrysotile, mixed and amphibole fibres, respectively, meta-RRs for neighbourhood studies were 3.8 (95% CI 0.4 to 38.4), 8.4 (95% CI 4.7 to 14.9) and 21.1 (95% CI 5.3 to 84.5) and meta-RRs for household studies were 4.0 (95% CI 0.8 to 18.8), 5.3 (95% CI 1.9 to 15.0) and 21.1 (95% CI 2.8 to 156.0).

Conclusions: PMM risks from non-occupational asbestos exposure are consistent with the fibre-type potency response observed in occupational settings. By relating our findings to knowledge of exposure-response relationships in occupational settings, we can better evaluate PMM risks in communities with ambient asbestos exposures from industrial or other sources.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Pleural abnormalities in the Framingham Heart Study: prevalence and CT image features. T. Araki, M. Yanagawa, F.J. Sun, et al. 2017;74(10):756-761. PubMed · Publisher · Free full text

Abstract

Background: The prevalence of pleural abnormalities in the general population is an epidemiologically important index of asbestos exposure, which has not been investigated since a radiography-based study in 1980.

Methods: We examined 2633 chest CT scans (mean 59.2 years, 50% female) from the Framingham Heart Study (FHS) for the presence and image characteristics of pleural plaques and diffuse pleural thickening. Demographics and pulmonary function were stratified by the presence of pleural abnormalities in association with interstitial lung abnormalities.

Results: Pleural abnormalities were present in 1.5% (95% CI 1.1% to 2.1%). Pleural lesions were most commonly bilateral (90.0%), multiple (77.5%), calcified (97.5%) and commonly involved posterior (lower: 92.5%, middle: 87.5%), anterior (upper: 77.5%, middle: 77.5%) and diaphragmatic areas (72.5%). Participants with pleural abnormalities were significantly older (75.7 years, p <0.0001), male (92.5%, p <0.0001), former or current smokers (80.0%, p <0.001) with higher pack-years (33.3, p <0.0001). No significant reduction was noted in pulmonary function measures (p=0.07-0.94) when adjusted for the associated covariates, likely due to small number of cases with pleural abnormalities. Information about prior history of asbestos exposure and occupation was not available.

Conclusions: Pleural plaques and diffuse pleural thickening are present on CT in 1.5% of the FHS cohort. The current prevalence of the pleural abnormalities is smaller than that reported in the previous population-based study using chest radiography, likely representing lower asbestos exposure in recent decades. The posterior portion of the pleura is most frequently involved but the anterior portion is also commonly involved.

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Pleural mesothelioma and asbestos exposure: a case-control study with quantitative risk assessment-response to Marsh and Benson's letter. D. Ferrante, D. Mirabelli, S. Tunesi, et al. 2017;74(2):157-158. Letter · Comment PubMed · Publisher
Quantitative estimated exposure to vinyl chloride and risk of angiosarcoma of the liver and hepatocellular cancer in the US industry-wide vinyl chloride cohort: mortality update through 2013. K.A. Mundt, L.D. Dell, L. Crawford, et al. 2017;74(10):709-716. PubMed · Publisher · Free full text

Abstract

Objective: To evaluate mortality risks of angiosarcoma of the liver (ASL), primary hepatocellular carcinoma (HCC) and other cancers among 9951 men employed between 1942 and 1972 at 35 US vinyl chloride (VC) or polyvinyl chloride plants followed for mortality through 31 December 2013.

Methods: SMR and time-dependent Cox proportional hazards analyses were used to evaluate mortality risks by cumulative VC exposure.

Results: Liver cancer mortality was elevated (SMR=2.87, 95% CI 2.40 to 3.40), and ASL and HCC were strongly associated with cumulative VC exposure ≥865 parts per million-years (ppm-years) (ASL: HR=36.3, 95% CI 13.1 to 100.5; and HCC: HR=5.3, 95% CI 1.6 to 17.7 for ≥2271 ppm-years). Excess deaths due to connective and soft tissue cancers (SMR=2.43, 95% CI 1.48 to 3.75), mesothelioma (SMR=2.29, 95% CI 1.18 to 4.00) and explosions (SMR=3.43, 95% CI 1.25 to 7.47) were seen. Mortalities due to melanoma, brain cancer, lung cancer and non-Hodgkin's lymphoma were not increased or associated with VC exposure.

Conclusion: The association between VC and ASL first reported in this cohort 44 years ago persisted and was strongest among workers most highly exposed. VC exposure also was associated with HCC mortality, although it remains possible that misdiagnosis of early ASLs influenced findings.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Residual fibre lung burden among patients with pleural mesothelioma who have been occupationally exposed to asbestos. E. Merler, A. Somigliana, P. Girardi, et al. 2017;74(3):218-227. PubMed · Publisher

Abstract

Objectives: To evaluate the lungs asbestos fibres concentration in participants with malignant pleural mesothelioma (MPM) who have been occupationally exposed.

Methods: The lung samples were obtained from pleuropneumonectomies or autopsies of 271 male MPMs. The lung samples were examined through scanning electron microscopy. Retrospective assessment was used to assess for asbestos exposure. This study includes 248 MPMs with an occupational exposure defined as either 'definite' or 'probable' or 'possible'.

Results: The participants had finished working in asbestos exposure conditions more than 20 years ago (on average 26.1±11.0 years). The fibre burden resulted with a geometric mean equal to 2.0 (95% CI 1.6 to 2.4) million fibres per gram of dry lung tissue. The burden was higher among participants employed in asbestos textiles industry and in shipyards with insulation material, if compared with construction workers or non-asbestos textile workers or participants working in chemicals or as auto mechanics. 91.3% of MPMs had a detectable amount of amphibole fibres. A strong lung clearance capability was evident among workers exposed to chrysotile fibres. Owing to that, the 1997 Helsinki Criteria for occupational exposure were reached in <35% of cases among participant working in construction, in metallurgical industry, in chemical or textile industry and among those performing brake repair activities.

Conclusions: The MPM cases are now occurring in Italy in participants who ceased occupational asbestos exposure decades before the analysis. A large majority still shows a residual content of amphibole fibres, but given the lung clearance capability, attribution to occupational exposure cannot rely only on fibres detection.

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Response to: 'Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment' by Ferrante et al. G.M. Marsh, S.M. Benson. 2017;74(2):156-157. Letter · Comment PubMed · Publisher

Summary

In this letter, the authors responded to a 2016 case-control study by Ferrante et al of occupational and non-occupational asbestos exposure and pleural malignant mesothelioma (PMM) risk among workers and residents of Casale Monferrato, Italy, site of a former asbestos cement factory. They noted that a letter by Boffetta had raised methodological concerns, including limited exposure-estimation detail, lack of reproducibility, inconsistent findings and possible biases, which Ferrante et al's reply had not fully resolved. The authors' own critical evaluation supported these concerns and found a further problem: inconsistency with other studies of non-occupational exposure. In a meta-analysis by Bourdes et al (eight studies, 13 risk estimates), only two estimates were of the same order of magnitude as Ferrante et al's, and the rest were below 10. In Hansen et al's study of crocidolite exposure among residents of Wittenoom, Australia, the highest exposure group (20 to 40.4 f/mL years) had PMM risk estimates of 3.6 or 6.3. Ferrante et al's highest environmental group had about half that exposure (10 to 24 f/mL years) but risks 2.3-fold to fourfold higher. The authors also stated that Ferrante et al's risk patterns conflicted with the established view that PMM risks are greater for amphibole fibres. They concluded that this cast further doubt on the validity and usefulness of Ferrante et al's results. One author declared acting as an expert witness for defence attorneys in criminal trials on asbestos-related cancers.

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The economic burden of lung cancer and mesothelioma due to occupational and para-occupational asbestos exposure. E. Tompa, C. Kalcevich, C. McLeod, et al. 2017;74(11):816-822. PubMed · Publisher · Free full text

Abstract

Objectives: To estimate the economic burden of lung cancer and mesothelioma due to occupational and para-occupational asbestos exposure in Canada.

Methods: We estimate the lifetime cost of newly diagnosed lung cancer and mesothelioma cases associated with occupational and para-occupational asbestos exposure for calendar year 2011 based on the societal perspective. The key cost components considered are healthcare costs, productivity and output costs, and quality of life costs.

Results: There were 427 cases of newly diagnosed mesothelioma cases and 1904 lung cancer cases attributable to asbestos exposure in 2011 for a total of 2331 cases. Our estimate of the economic burden is $C831 million in direct and indirect costs for newly identified cases of mesothelioma and lung cancer and $C1.5 billion in quality of life costs based on a value of $C100 000 per quality-adjusted life year. This amounts to $C356 429 and $C652 369 per case, respectively.

Conclusions: The economic burden of lung cancer and mesothelioma associated with occupational and para-occupational asbestos exposure is substantial. The estimate identified is for 2331 newly diagnosed, occupational and para-occupational exposure cases in 2011, so it is only a portion of the burden of existing cases in that year. Our findings provide important information for policy decision makers for priority setting, in particular the merits of banning the mining of asbestos and use of products containing asbestos in countries where they are still allowed and also the merits of asbestos removal in older buildings with asbestos insulation.

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A case-control study of mesothelioma in Minnesota iron ore (taconite) miners. C.S. Lambert, B.H. Alexander, G. Ramachandran, et al. 2016;73(2):103-9. PubMed · Publisher · Free full text

Abstract

Objectives: An excess of mesothelioma has been observed in iron ore miners in Northeastern Minnesota. Mining and processing of taconite iron ore generate exposures that include elongate mineral particles (EMPs) of amphibole and non-amphibole origin. We conducted a nested case-control study of mesothelioma in a cohort of 68,737 iron ore miners (haematite and taconite ore miners) to evaluate the association between mesothelioma, employment and EMP exposures from taconite mining.

Methods: Mesothelioma cases (N=80) were identified through the Minnesota Cancer Surveillance System (MCSS) and death certificates. Four controls of similar age were selected for each case with 315 controls ultimately eligible for inclusion. Mesothelioma risk was evaluated by estimating rate ratios and 95% CIs with conditional logistic regression in relation to duration of taconite industry employment and cumulative EMP exposure [(EMP/cc)×years], defined by the National Institute for Occupational Safety and Health (NIOSH) 7400 method. Models were adjusted for employment in haematite mining and potential exposure to commercial asbestos products used in the industry.

Results: All mesothelioma cases were male and 57 of the cases had work experience in the taconite industry. Mesothelioma was associated with the number of years employed in the taconite industry (RR=1.03, 95% CI 1.00 to 1.06) and cumulative EMP exposure (RR=1.10, 95% CI 0.97 to -1.24). No association was observed with employment in haematite mining.

Conclusions: These results support an association between mesothelioma and employment duration and possibly EMP exposure in taconite mining and processing. The type of EMP was not determined. The potential role of commercial asbestos cannot be entirely ruled out.

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Asbestos exposure and histological subtype of malignant mesothelioma. P. Franklin, H. Alfonso, A. Reid, et al. 2016;73(11):749-752. PubMed · Publisher

Abstract

Background: Malignant mesothelioma (MM) has distinct histological subtypes (epithelioid, sarcomatoid and biphasic) with variable behaviour and prognoses. It is well recognised that survival time varies with the histological subtype of MM. It is not known, however, if asbestos exposure characteristics (type of asbestos, degree of exposure) are associated with different histological subtypes.

Aim: To determine if the pathological MM subtype is associated with the type of asbestos or the attributes of asbestos exposure.

Methods: Cases of MM for the period 1962 until 2012, their main histological subtype and their most significant source of asbestos exposure were collected from the Western Australian Mesothelioma Registry. Exposure characteristics included, degree of asbestos exposure (including total days exposed, years since first exposure and, for crocidolite only, calculated cumulative exposure), source of exposure (occupational or environmental), form of asbestos handled (raw or processed) and type of asbestos (crocidolite only or mixed fibres).

Results: Patients with the biphasic subtype were more likely to have occupational exposure (OR 1.83, 1.12 to 2.85) and exposure to raw fibres (OR 1.58, 1.19 to 2.10). However, differences between subtypes in the proportions with these different exposure characteristics were small and unlikely to be biologically relevant. Other indicators of asbestos exposure were not associated with the histological subtype of mesothelioma.

Conclusions: There was no strong evidence of a consistent role of asbestos exposure indicators in determining the histological subtype of MM.

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Authors's response: Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment. D. Ferrante, D. Mirabelli, S. Tunesi, et al. 2016;73(10):713-4. Letter · Comment PubMed · Publisher

Summary

In this letter, the authors of a published case-control study of pleural mesothelioma and occupational and non-occupational asbestos exposure in Casale Monferrato, Italy, replied to criticisms of that study by Boffetta. They stated that proxy respondents made up 7.2% of controls, not 93% as Boffetta had indicated, and that the exposure-response trend was steeper for direct interviews. They argued that awareness of asbestos-related cancer risks applied to the whole local community, not only to cases. They said that if exposed controls had selectively entered the study, the findings would be biased towards the null. They reported that, after publication, they had found no differences in demographic and social characteristics between respondents and non-respondents (paper in preparation). They defended their expert-based retrospective exposure assessment, while acknowledging that it was not a perfect method and was difficult to reproduce and document. They cited a systematic review for the Second Italian Consensus Conference on Pleural Mesothelioma. That review identified eight cohort, three nested and two population-based case-control studies on cumulative exposure, and seven case-control studies on lung burden, and consistently showed mesothelioma risk proportional to cumulative exposure. In their own data, a model with cumulative exposure fitted better than a model with latency (AIC 501.3 vs 557.5). A model with both was unstable but showed the same trend. They explained that reference categories differed between models in supplementary tables S1 and S2, so those estimates should not be compared directly. They also noted that environmental exposure could be a negative confounder. They confirmed their conclusion that cumulative exposure is important for mesothelioma risk and said this supports asbestos bans and remediation.

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Cancer mortality in a population exposed to nephrite processing. H.Y. Yang, S.H. Huang, R.H. Shie, et al. 2016;73(8):528-36. PubMed · Publisher

Abstract

Objectives: Although asbestos has been recognised as a strong carcinogen, many asbestos minerals exist in concrete masses, and the health risks of these materials remain inconclusive. Nephrite jade is a concrete mass of amphibole that consists of asbestiform and non-asbestiform particles. The objective of the study was to explore the carcinogenetic effect of nephrite.

Methods: We examined cancer mortality between 1979 and 2011 in Fengtian, where nephrite was mass produced from 1970 to 1980, and calculated standardised mortality ratios (SMRs).

Results: We observed significantly elevated mortality risks for cancer of the hypopharynx (SMR 2.31; 95% CI 1.37 to 3.65), larynx (SMR 2.51; 95% CI 1.55 to 3.83), oesophagus (SMR 2.04; 95% CI 1.62 to 2.54) and stomach (SMR 1.38; 95% CI 1.17 to 1.63). This study analysed the lengths, widths, structures, chemical compositions, aerodynamic diameters and distributions of elongated mineral particles (EMPs) in airways. The majority of the EMPs (68%) were short (<5 μm) and thin (<0.5 µm), and possessed asbestiform structures. The median aerodynamic diameter of the EMPs was 1.2 μm. The total deposition proportion in airways was 51.3%. The major deposition sites were the head airway (37.5%), followed by the alveolar region (10.6%) and the tracheobronchial region (3.2%).

Conclusions: The results have shown an association between EMPs and increased risk of respiratory and digestive cancers. Further research is needed that includes information on smoking habits and exposure to asbestos.

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Expected number of asbestos-related lung cancers in the Netherlands in the next two decades: a comparison of methods. S. Van der Bij, R.C. Vermeulen, L. Portengen, et al. 2016;73(5):342-9. PubMed · Publisher

Abstract

Objectives: Exposure to asbestos fibres increases the risk of mesothelioma and lung cancer. Although the vast majority of mesothelioma cases are caused by asbestos exposure, the number of asbestos-related lung cancers is less clear. This number cannot be determined directly as lung cancer causes are not clinically distinguishable but may be estimated using varying modelling methods.

Methods: We applied three different modelling methods to the Dutch population supplemented with uncertainty ranges (UR) due to uncertainty in model input values. The first method estimated asbestos-related lung cancer cases directly from observed and predicted mesothelioma cases in an age-period-cohort analysis. The second method used evidence on the fraction of lung cancer cases attributable (population attributable risk (PAR)) to asbestos exposure. The third method incorporated risk estimates and population exposure estimates to perform a life table analysis.

Results: The three methods varied substantially in incorporated evidence. Moreover, the estimated number of asbestos-related lung cancer cases in the Netherlands between 2011 and 2030 depended crucially on the actual method applied, as the mesothelioma method predicts 17 500 expected cases (UR 7000-57 000), the PAR method predicts 12 150 cases (UR 6700-19 000), and the life table analysis predicts 6800 cases (UR 6800-33 850).

Conclusions: The three different methods described resulted in absolute estimates varying by a factor of ∼2.5. These results show that accurate estimation of the impact of asbestos exposure on the lung cancer burden remains a challenge.

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Incidence and survival trends for malignant pleural and peritoneal mesothelioma, Australia, 1982-2009. M.J. Soeberg, J. Leigh, T. Driscoll, et al. 2016;73(3):187-94. PubMed · Publisher

Abstract

Background: Australia is known to have had one of the highest per-capita asbestos consumption rates, yet there are few contemporary reports on malignant mesothelioma trends.

Methods: Data on 10 930 people with malignant pleural mesothelioma (MPM) and 640 people with malignant peritoneal mesothelioma diagnosed in Australia during 1982-2009 were analysed. Observed incidence rate trends were quantified. Incidence rates were projected up to 2030 using observed incident cases during 1982-2012. The relative per-decade change in excess mortality during 1999-2009 was estimated.

Results: During 1982-2009, acceleration in MPM age-standardised incidence rates were highest for women and those aged 75 years and above, with average annual percentage changes of +4.9 (95% CI 3.6 to 6.2) and +7.2 (95% CI 5.4 to 9.0), respectively. Age-standardised incidence rates for men with MPM aged 0-64 years decelerated rapidly during 2003-2009, an average annual percentage change of -5.1% (95% CI -7.6% to -2.5%). Overall, male age-specific MPM incidence rates in the age group of 65-74 year during 2010-2030 are projected to decline with rates projected to increase for older men and women with MPM. There was a statistically significant 16% relative reduction in the excess mortality rate (EMR) up to 5 years postdiagnosis for people diagnosed with malignant pleural and peritoneal mesothelioma combined in 2009 compared with those diagnosed in 1999, an EMR ratio of 0.84 (95% CI 0.77 to 0.92).

Conclusions: Australia's malignant mesothelioma incidence rates appear to have reached maximum levels but with differences over time by age, gender and tumour location. Improvements over time in survival provide a glimpse of hope for this almost invariably fatal disease.

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Incidence of mesothelioma in Lombardy, Italy: exposure to asbestos, time patterns and future projections. C. Mensi, S. De Matteis, B. Dallari, et al. 2016;73(9):607-13. PubMed · Publisher · Free full text

Abstract

Objectives: In Italy, asbestos has been extensively used from 1945 to 1992. We evaluated the impact of exposure to asbestos on occurrence of malignant mesothelioma (MM) in the Lombardy Region, Northwest Italy, the most populated and industrialised Italian region.

Methods: From the Lombardy Mesothelioma Registry, we selected all incident cases of MM diagnosed between 2000 and 2012. We described sources of exposure to asbestos and examined time trends of MM rates. Using Poisson age-cohort models, we derived projections of burden of MM in the Lombardy population for the period 2013-2029.

Results: In 2000-2012, we recorded 4442 cases of MM (2850 men, 1592 women). Occupational exposure to asbestos was more frequent in men (73.6%) than in women (38.2%). Non-occupational exposure was found for 13.6% of women and 3.6% of men. The average number of cases of MM per year was still increasing (+3.6% in men, +3.3% in women). Incidence rates were still increasing in individuals aged 65+ years and declining in younger people. A maximum of 417 cases of MM (267 men, 150 women) are expected in 2019. We forecast there will be 6832 more cases (4397 in men, 2435 in women) in the period 2013-2029, for a total of 11 274 cases of MM (7247 in men, 4027 in women) in 30 years.

Conclusions: This study documented a high burden of MM in both genders in the Lombardy Region, reflecting extensive occupational (mainly in men) and non-occupational (mainly in women) exposure to asbestos in the past. Incidence rates are still increasing; a downturn in occurrence of MM is expected to occur after 2019.

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Mesothelioma in iron ore (taconite) miners. D. Mirabelli. 2016;73(4):217-8. Comment PubMed · Publisher
Multidimensional analysis of the effect of occupational exposure to organic solvents on lung cancer risk: the ICARE study. F. Mattei, S. Liverani, F. Guida, et al. 2016;73(6):368-77. PubMed · Publisher · Free full text

Abstract

Background: The association between lung cancer and occupational exposure to organic solvents is discussed. Since different solvents are often used simultaneously, it is difficult to assess the role of individual substances.

Objectives: The present study is focused on an in-depth investigation of the potential association between lung cancer risk and occupational exposure to a large group of organic solvents, taking into account the well-known risk factors for lung cancer, tobacco smoking and occupational exposure to asbestos.

Methods: We analysed data from the Investigation of occupational and environmental causes of respiratory cancers (ICARE) study, a large French population-based case-control study, set up between 2001 and 2007. A total of 2276 male cases and 2780 male controls were interviewed, and long-life occupational history was collected. In order to overcome the analytical difficulties created by multiple correlated exposures, we carried out a novel type of analysis based on Bayesian profile regression.

Results: After analysis with conventional logistic regression methods, none of the 11 solvents examined were associated with lung cancer risk. Through a profile regression approach, we did not observe any significant association between solvent exposure and lung cancer. However, we identified clusters at high risk that are related to occupations known to be at risk of developing lung cancer, such as painters.

Conclusions: Organic solvents do not appear to be substantial contributors to the occupational risk of lung cancer for the occupations known to be at risk.

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New standard for assessing asbestos exposure and its consequences?. L.C. Oliver, L. Welch, A.L. Frank, et al. 2016;73(10):709-10. Letter · Comment PubMed · Publisher
Para-occupational exposures to asbestos: lessons learned from Casale Monferrato, Italy. L.T. Stayner. 2016;73(3):145-6. Comment PubMed · Publisher

Summary

In this commissioned commentary, the author discussed a case-control study by Ferrante et al. of pleural mesothelioma and asbestos exposure in Casale Monferrato, Italy, the site of an Eternit asbestos cement plant. That study found roughly twofold risks for having lived with a family member who worked at the plant (OR=2.4, 95% CI 1.3 to 4.4) and for domestic or environmental exposure (OR=2.0, 95% CI 1.2 to 3.2). The author highlighted its analysis of exposure-response across all sources of cumulative exposure. That analysis found an approximately fourfold risk at 0.1 to <1 fibre/mL-years (OR=4.4, 95% CI 1.7 to 11.3) and a similar risk for non-occupational sources alone (OR=3.8, 95% CI 1.3 to 11.1). He calculated that 1 fibre/mL-year corresponded to about 0.01 fibre/mL over 70 years of residence, roughly two orders of magnitude below levels reported in the past in other asbestos communities. Asbestos-cement roofing (OR=2.5) and pavement with asbestos tailings (OR=3.6) were also associated with mesothelioma. The author argued that continued worldwide use of about two million metric tons per year remained a concern even where only chrysotile was used, given the risks of lung, laryngeal and ovarian cancer and asbestosis. He noted cleanup costs in Libby, Montana, of at least $447 million since 1999. He concluded that countries using or producing asbestos should heed the lessons of Casale Monferrato, Libby and other affected communities.

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Pleural mesothelioma and lung cancer risks in relation to occupational history and asbestos lung burden. C. Gilham, C. Rake, G. Burdett, et al. 2016;73(5):290-9. PubMed · Publisher · Free full text

Abstract

Background: We have conducted a population-based study of pleural mesothelioma patients with occupational histories and measured asbestos lung burdens in occupationally exposed workers and in the general population. The relationship between lung burden and risk, particularly at environmental exposure levels, will enable future mesothelioma rates in people born after 1965 who never installed asbestos to be predicted from their asbestos lung burdens.

Methods: Following personal interview asbestos fibres longer than 5 µm were counted by transmission electron microscopy in lung samples obtained from 133 patients with mesothelioma and 262 patients with lung cancer. ORs for mesothelioma were converted to lifetime risks.

Results: Lifetime mesothelioma risk is approximately 0.02% per 1000 amphibole fibres per gram of dry lung tissue over a more than 100-fold range, from 1 to 4 in the most heavily exposed building workers to less than 1 in 500 in most of the population. The asbestos fibres counted were amosite (75%), crocidolite (18%), other amphiboles (5%) and chrysotile (2%).

Conclusions: The approximate linearity of the dose-response together with lung burden measurements in younger people will provide reasonably reliable predictions of future mesothelioma rates in those born since 1965 whose risks cannot yet be seen in national rates. Burdens in those born more recently will indicate the continuing occupational and environmental hazards under current asbestos control regulations. Our results confirm the major contribution of amosite to UK mesothelioma incidence and the substantial contribution of non-occupational exposure, particularly in women.

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In plain English

This British population-based study compared the amount of asbestos in the lungs of 133 people with pleural mesothelioma with that of 262 people who had surgery for lung cancer, who served as the comparison group. Patients were interviewed about their work histories. Asbestos fibres longer than 5 micrometres were counted by electron microscopy. Most fibres found were amosite (75%) or crocidolite (18%). Chrysotile made up 1.9%. Among men, the odds of mesothelioma rose with lung burden. In the highest group (1.0 million fibres per dry gram of lung or more), the odds ratio was 35.00 (95% CI 7.22 to 169.6) compared with the lowest group. The authors estimated lifetime mesothelioma risk at about 0.020% per 1000 asbestos fibres per gram of dry lung. All 27 male mesothelioma patients with burdens above 0.5 million fibres per gram had worked in high-risk jobs. Carpenters had the highest amosite levels. Burdens in women were much lower. The authors concluded that amosite contributed heavily to UK mesothelioma and that non-occupational exposure contributed substantially, particularly in women. There were too few women to analyse them separately.

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Pleural mesothelioma and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment. D. Ferrante, D. Mirabelli, S. Tunesi, et al. 2016;73(3):147-53. PubMed · Publisher

Abstract

Objectives: Casale Monferrato (north west Italy) is an area with an exceptionally high incidence of mesothelioma caused by asbestos contamination at work and in the general environment from the asbestos-cement Eternit plant that was operational until 1986. The purpose of this study was to quantify the association between pleural malignant mesothelioma (PMM) and asbestos cumulative exposure using individual assessment of environmental and domestic exposure, as well as of occupational exposure.

Methods: This population-based case-control study included cases of PMM diagnosed between January 2001 and June 2006 among residents in the Casale Monferrato Local Health Authority. Population controls were randomly sampled, matched by age and sex to cases. Cumulative exposure was estimated to account for the lifelong exposure history. Analyses were conducted using unconditional logistic regression models adjusting for gender, age at diagnosis and type of interview (direct or proxy respondents).

Results: 200 PMM cases of 223 eligible cases (89.7%) and 348 (63%) of 552 eligible controls accepted to be interviewed. ORs increased with cumulative exposure index (p<0.0001) from 4.4 (CI 95% 1.7 to 11.3) (<1 f/mL-years) to 62.1 (CI 95% 22.2 to 173.2) (≥10 f/mL-years). Among subjects never occupationally exposed, corresponding ORs were 3.8 (CI 95% 1.3 to 11.1) and 23.3 (CI 95% 2.9 to 186.9) (reference: background level of asbestos exposure). ORs of about 2, statistically significant, were observed for domestic exposure and for living in houses near buildings with large asbestos cement parts.

Conclusions: Risk of PMM increased with cumulative asbestos exposure and also in analyses limited to subjects non-occupationally exposed. Our results also provide indication of risk associated with common sources of environmental exposure and are highly relevant for the evaluation of residual risk after the cessation of asbestos industrial use.

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Response to: Pleural mesothelioma, and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment. P. Boffetta. 2016;73(10):712. Letter · Comment PubMed · Publisher

Summary

In this letter, the author responded to a case-control study by Ferrante et al of pleural mesothelioma in Casale Monferrato. That study had reported associations with occupational and non-occupational (household and residential) asbestos exposure and focused on quantitative risk estimates. The author stated that the qualitative findings matched those reported in other heavily exposed populations, but argued that important limitations restricted interpretation of the quantitative results. He noted response rates of 89% among cases and 63% among controls, and proxy interviews for 46% of cases and 93% of controls. He described these differences as potential sources of selection and information bias, with reporting bias of particular concern given local knowledge of asbestos hazards. He cited findings he considered anomalous. Odds ratios for environmental exposure appeared higher than those for occupational exposure at the same exposure levels, notably in the highest category, despite lower average exposure (15 vs 260 fb/mL years). Odds ratios also increased as the specificity of exposure assessment decreased. He further stated that exposure assessment methods were insufficiently described, and that retrospective estimates based on scanty environmental data may overestimate the dose-response slope. He also argued that the focus on cumulative exposure obscured the role of time since first exposure. He concluded that the study failed to provide a reliable quantitative estimate of the association. The author declared having acted as an expert witness in asbestos-related litigation.

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Setting new standards for epidemiological research on mesothelioma. P. Boffetta, C. La Vecchia. 2016;73(5):289. Comment PubMed · Publisher

Summary

In this commissioned commentary, the authors discussed a study by Gilham et al, published in the same journal. That study was the first to use lung fibre burden to estimate past asbestos exposure in a large British population-based study of pleural mesothelioma. The commentators noted possible sources of bias. Lung samples were analysed for 134 cases, 21.5% of the original case-control study. Controls were resected lung cancer cases, who represent less advanced disease and would be expected to have higher fibre burdens than the general population. Sample retrieval among controls was 262/420 (62.4%). They wrote that a quantitative assessment of selection bias would have been helpful. In their view, the study confirmed the predominant role of amphibole exposure. They noted that lung burden studies cannot adequately estimate the effect of chrysotile because of its short biopersistence. They considered the most important result to be the linear dose-response between amphibole lung burden and mesothelioma risk, as predicted by the 1982 model of Peto et al. They also highlighted the first fibre-burden-based estimate of the relative effect of crocidolite versus amosite. Many cases in low-risk occupations had relatively high fibre burdens. The authors suggested that job-based assessment would miss occupation-related cases and that fibre burden analysis could help identify cases deserving compensation. Alternatively, environmental exposures may have contributed. They concluded that the study set a new standard and stressed the value of collecting tissue samples. Both authors declared that they had acted as expert witnesses in asbestos-related litigation.

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Simple benchmark for mesothelioma projection for Great Britain. M.D. Martínez-Miranda, B. Nielsen, J.P. Nielsen. 2016;73(8):561-3. PubMed · Publisher

Abstract

Background: It is of considerable interest to forecast the future burden of mesothelioma mortality. Data on deaths are available, whereas no measure of asbestos exposure is available.

Methods: We compare two Poisson models: a response-only model with an age-cohort specification and a multinomial model with epidemiologically motivated frequencies.

Results: The response-only model has 5% higher peak mortality than the dose-response model. The former performs slightly better in out-of-sample comparison.

Conclusions: Mortality is predicted to peak at about 2100 deaths around 2017 among males in cohorts until 1966 and below 90 years of age. The response-only model is a simple benchmark that forecasts just as well as more complicated models.

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The joint effect of asbestos exposure, tobacco smoking and alcohol drinking on laryngeal cancer risk: evidence from the French population-based case-control study, ICARE. G. Menvielle, A. Fayossé, L. Radoï, et al. 2016;73(1):28-33. PubMed · Publisher

Abstract

Objective: The objective of the study was to investigate the joint effect of occupational exposure to asbestos, and tobacco and alcohol consumption, on the risk of laryngeal cancer among men.

Methods: We used data from a large population-based case-control study conducted in France. We estimated two-way and three-way interactions between asbestos exposure (never vs ever exposed), tobacco consumption (<20 vs. ≥20 pack-years) and alcohol consumption (<5 vs. ≥5 drinks per day). The interaction on an additive scale was assessed by estimating the relative excess risk due to interaction (RERI) and the attributable proportion due to interaction, and the interaction on a multiplicative scale was assessed by estimating the multiplicative interaction parameter (ψ). Multiplicative interactions were also assessed using fractional polynomials for alcohol drinking, tobacco smoking and asbestos exposure.

Results: When compared with light-to-moderate smokers and drinkers never exposed to asbestos, the increase in laryngeal cancer risk was smallest among light-to-moderate drinkers and smokers exposed to asbestos (OR=2.23 (1.08 to 4.60)), and highest among heavy smokers and drinkers ever exposed to asbestos (OR=69.39 (35.54 to 135.5)). We found an additive joint effect between asbestos exposure and alcohol consumption (RERI=4.75 (-4.29 to 11.12)), whereas we observed a more than additive joint effect between asbestos exposure and tobacco consumption (RERI=8.50 (0.71 to 23.81)), as well as between asbestos exposure, and tobacco and alcohol consumption (RERI=26.57 (11.52 to 67.88)). However, our results did not suggest any interaction on a multiplicative scale.

Conclusions: Our results suggest that asbestos exposure, in combination with tobacco and alcohol exposure, accounted for a substantial number of laryngeal cancer cases. Our findings therefore highlight the need for prevention in activities, such as construction work, where exposure to asbestos-containing materials remains.

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Trends in mortality from occupational hazards among men in England and Wales during 1979-2010. E.C. Harris, K.T. Palmer, V. Cox, et al. 2016;73(6):385-93. PubMed · Publisher · Free full text

Abstract

Objectives: To monitor the impact of health and safety provisions and inform future preventive strategies, we investigated trends in mortality from established occupational hazards in England and Wales.

Methods: We analysed data from death certificates on underlying cause of death and last full-time occupation for 3 688 916 deaths among men aged 20-74 years in England and Wales during 1979-2010 (excluding 1981 when records were incomplete). Proportional mortality ratios (PMRs), standardised for age and social class, were calculated for occupations at risk of specified hazards. Observed and expected numbers of deaths for each hazard were summed across occupations, and the differences summarised as average annual excesses.

Results: Excess mortality declined substantially for most hazards. For example, the annual excess of deaths from chronic bronchitis and emphysema fell from 170.7 during 1979-1990 to 36.0 in 2001-2010, and that for deaths from injury and poisoning from 237.0 to 87.5. In many cases, the improvements were associated with falling PMRs (suggesting safer working practices), but they also reflected reductions in the numbers of men employed in more hazardous jobs, and declining mortality from some diseases across the whole population. Notable exceptions to the general improvement were diseases caused by asbestos, especially in some construction trades and sinonasal cancer in woodworkers.

Conclusions: The highest priority for future prevention of work-related fatalities is the minority of occupational disorders for which excess mortality remains static or is increasing, in particular asbestos-related disease among certain occupations in the construction industry and sinonasal cancer in woodworkers.

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Unreliable proposed 'new standard' for assessing asbestos exposure. D. Egilman, X. Baur, C.L. Soskolne. 2016;73(10):709. Letter · Comment PubMed · Publisher
Welding, a risk factor of lung cancer: the ICARE study. M. Matrat, F. Guida, F. Mattei, et al. 2016;73(4):254-61. PubMed · Publisher

Abstract

Objectives: We investigated the relationship between lung cancer and occupational exposure to welding activity in ICARE, a population-based case-control study.

Methods: Analyses were restricted to men (2276 cases, 2780 controls). Welding exposure was assessed through detailed questionnaires, including lifelong occupational history. ORs were computed using unconditional logistic regression, adjusted for lifelong cigarette smoking and occupational exposure to asbestos.

Results: Among the regular welders, welding was associated with a risk of lung cancer (OR=1.7, 95% CI 1.1 to 2.5), which increased with the duration (OR=2.0, 95% CI 1.0 to 3.9 when duration >10 years), and was maximum 10-20 years since last welding. The risk was more pronounced in case of gas welding (OR=2.0, 95% CI 1.2 to 3.3), when the workpiece was covered by paint, grease, or other substances (OR=2.0, 95% CI 1.2 to 3.4) and when it was cleaned with chemical substances before welding. No statistically significant increase in lung cancer risk was observed among occasional welders.

Conclusions: Although these results should be confirmed, we showed that type of welding and mode of workpiece preparation are important determinants of the lung cancer risk in regular welders.

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A systematic review of the association between pleural plaques and changes in lung function. L. Kopylev, K.Y. Christensen, J.S. Brown, et al. 2015;72(8):606-14. Systematic review PubMed · Publisher · Free full text

Abstract

Objectives: To conduct a systematic review of changes in lung function in relation to presence of pleural plaques in asbestos-exposed populations.

Methods: Database searches of PubMed and Web of Science were supplemented by review of papers' reference lists and journals' tables of contents. Methodological features (eg, consideration of potential confounding by smoking) of identified articles were reviewed by ≥ two reviewers. Meta-analyses of 20 studies estimated a summary effect of the decrements in per cent predicted (%pred) forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) associated with presence of pleural plaques.

Results: Among asbestos-exposed workers, the presence of pleural plaques was associated with statistically significant decrements in FVC (4.09%pred, 95% CI 2.31 to 5.86) and FEV1 (1.99%pred, 95% CI 0.22 to 3.77). Effects of similar magnitude were seen when stratifying by imaging type (X-ray or high-resolution CT) and when excluding studies with potential methodological limitations. Undetected asbestosis was considered as an unlikely explanation of the observed decrements. Several studies provided evidence of an association between size of pleural plaques and degree of pulmonary decrease, and presence of pleural plaques and increased rate or degree of pulmonary impairment.

Conclusions: The presence of pleural plaques is associated with a small, but statistically significant mean difference in FVC and FEV1 in comparison to asbestos-exposed individuals without plaques or other abnormalities. From a public health perspective, small group mean decrements in lung function coupled with an increased rate of decline in lung function of the exposed population may be consequential.

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Authors' response: A systematic review of the association between pleural plaques and changes in lung function. L. Kopylev, K.Y. Christensen, J.W. Brown, et al. 2015;72(9):685-6. Letter · Comment PubMed · Publisher · Free full text
Comment on "A systematic review of the association between pleural plaques and changes in lung function" by Kopylev et al (2014). J.E. Goodman, L.E. Kerper, K. Zu, et al. 2015;72(9):684-5. Letter · Comment PubMed · Publisher
Digestive cancers and occupational asbestos exposure: incidence study in a cohort of asbestos plant workers. M. Boulanger, F. Morlais, V. Bouvier, et al. 2015;72(11):792-7. PubMed · Publisher

Abstract

Objective: The aim of our study was to estimate the incidence of digestive cancers within a cohort of asbestos-exposed workers.

Methods: Our study was based on a cohort of 2024 participants occupationally exposed to asbestos. The incidence of digestive cancers was calculated from 1 January 1978 to 31 December 2009 and compared with levels among the local general population using Standardised Incidence Ratios (SIRs). Asbestos exposure was assessed using the company's job-exposure matrix.

Results: 119 cases of digestive cancer were observed within our cohort, for an expected number of 77 (SIR=1.54 (1.28 to 1.85)). A significantly elevated incidence was observed for peritoneal mesothelioma, particularly in women. Significantly elevated incidences were also observed among men for: all digestive cancers, even when excluding peritoneal mesothelioma (SIR=1.50 (1.23 to 1.82)), oesophageal cancer (SIR=1.67 (1.08 to 2.47)) and liver cancer (SIR=1.85 (1.09 to 2.92)). Concerning colorectal cancer, a significant excess of risk was observed for men with exposure duration above 25 years (SIR=1.75 (1.05 to 2.73)).

Conclusions: Our results are in favour of a link between long-duration asbestos exposure and colorectal cancer in men. They also suggest a relationship between asbestos exposure and cancer of the oesophagus in men. Finally, our results suggest a possible association with small intestine and liver cancers in men.

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Erionite and cancer in a Mexican village. R. Saracci. 2015;72(3):163-4. Editorial · Comment PubMed · Publisher

Summary

This commissioned commentary discussed a report by Ortega-Guerrero et al on lung cancer and malignant mesothelioma in Tierra Blanca de Abajo, a village in Central Mexico with 254 inhabitants (134 men, 120 women) in 2012. In that report, lung cancer death rates were about 70 times higher than in the state of Guanajuato for men (eight cases) and 100 times higher for women (six cases). Mesothelioma rates, based on four cases, were 248 and 105 per 100 000 person-years in men and women respectively. Chrysotile asbestos-cement roofing was present but was equally present in nearby villages without high cancer rates. Erionite was found in local tuff, alluvial terraces and adobe bricks. The author compared these findings with studies of Karain, Turkey, where an outbreak of 36 pleural mesotheliomas was reported in 1978 without detectable asbestos exposure. Pleural mesothelioma death rates there were of the order of 1000 per 100 000 person-years, and a 1979–2003 follow-up found 658 (men) and 697 (women) per 100 000 person-years. Erionite is classified by IARC as carcinogenic to humans. The author noted what the Mexican report lacked: independent confirmatory observations, airborne fibre measurements, radiological findings, information on family aggregation, and enough cases for age-specific analysis. He concluded that further observation and data should allow the hypothesis of an erionite-caused hotspot outside Turkey to be substantiated.

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Extended follow-up of lung cancer and non-malignant respiratory disease mortality among California diatomaceous earth workers. L.G. Gallagher, R.M. Park, H. Checkoway. 2015;72(5):360-5. PubMed · Publisher

Abstract

Objectives: Millions of workers worldwide are employed in occupations involving potentiality hazardous exposure to crystalline silica. The diatomaceous earth industry can have particularly high exposures, but there is a lower likelihood of simultaneously occurring confounding exposures. We extended follow-up for diatomaceous earth industry workers previously studied for mortality.

Methods: The cohort included 2342 white men who were employed for at least 1 year at a diatomaceous earth plant in Lompoc, California beginning in 1942. Workers' vital status was updated using the National Death Index through 2011, an extension of 19 years from earlier studies. Detailed work history and quantitative air monitoring measurements estimated exposure intensity. Cox proportional hazards modelling estimated HRs and 95% CIs. SMRs were calculated.

Results: Elevated mortality was observed by quartile of cumulative crystalline silica exposure for lung cancer (HR=2.03, 95% CI 1.07 to 3.85, highest quartile, unlagged) and non-malignant respiratory disease (NMRD) (HR=3.59, 95% CI 1.94 to 6.67, highest quartile, unlagged), although trends were not statistically significant. Associations were attenuated when adjusted for smoking and asbestos exposure. Mortality from NMRD was significantly increased over the entire follow-up compared to the general population (SMR=1.37, 95% CI 1.17 to 1.60). An increase for lung cancer was confined to the earlier follow-up (SMR=1.29, 95% CI 1.01 to 1.61).

Conclusions: The risk of lung cancer and NMRD mortality remained elevated, although generally non-significant, and exposure-response trends with cumulative crystalline silica persisted on extended follow-up of this cohort. The findings support a generally consistently observed aetiological relation between crystalline silica and lung cancer.

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High incidence of lung cancer and malignant mesothelioma linked to erionite fibre exposure in a rural community in Central Mexico. M.A. Ortega-Guerrero, G. Carrasco-Núñez, H. Barragán-Campos, et al. 2015;72(3):216-8. PubMed · Publisher

Abstract

Objective: To report the high incidence of lung cancer (LC) and malignant mesothelioma (MM) linked to environmental exposure to erionite fibres in a rural village of central Mexico.

Methods: This is a retrospective survey of clinical and mortality records from the years 2000-2012, accompanied by an environmental survey for nine Group-1 lung and pleura carcinogenic agents listed by the International Agency for Research on Cancer (IARC).

Results: Out of a total of 45 deaths between 2000 and 2012, 14 deaths correspond to different neoplasms of the lung, and at least four deaths to MM. The ages at diagnosis of MM were between 30 and 54 years. Annual age-standardised mortality rates per thousand due to LC and MM in the village (age >20 years) are 7.09 and 2.48 for males, and 4.75 and 1.05 for females, respectively. Erionite fibres were found in exposed rocks and soils, which can easily become airborne and be carried into streets and recreational areas near schools and homes. Other carcinogenic elements and minerals are found only in trace amounts, except for quartz dust and asbestos (chrysotile) cement sheeting, which are also present in the neighbouring villages.

Conclusions: These results indicate that environmental exposure to erionite is the main cause of the high rates of MM mortality in the Village of Tierra Blanca, supporting previous similar reports for people exposed to erionite fibres in villages in Turkey.

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Malignant mesothelioma due to non-occupational asbestos exposure from the Italian national surveillance system (ReNaM): epidemiology and public health issues. A. Marinaccio, A. Binazzi, M. Bonafede, et al. 2015;72(9):648-55. PubMed · Publisher

Abstract

Introduction: Italy produced and imported a large amount of raw asbestos, up to the ban in 1992, with a peak in the period between 1976 and 1980 at about 160,000 tons/year. The National Register of Mesotheliomas (ReNaM, "Registro Nazionale dei Mesoteliomi" in Italian), a surveillance system of mesothelioma incidence, has been active since 2002, operating through a regional structure.

Methods: The Operating Regional Center (COR) actively researches cases and defines asbestos exposure on the basis of national guidelines. Diagnostic, demographic and exposure characteristics of non-occupationally exposed cases are analysed and described with respect to occupationally exposed cases.

Results: Standardised incidence rates for pleural mesothelioma in 2008 were 3.84 (per 100,000) for men and 1.45 for women, respectively. Among the 15,845 mesothelioma cases registered between 1993 and 2008, exposure to asbestos fibres was investigated for 12,065 individuals (76.1%), identifying 530 (4.4%) with familial exposure (they lived with an occupationally exposed cohabitant), 514 (4.3%) with environmental exposure to asbestos (they lived near sources of asbestos pollution and were never occupationally exposed) and 188 (1.6%) exposed through hobby-related or other leisure activities. Clusters of cases due to environmental exposure are mainly related to the presence of asbestos-cement industry plants (Casale Monferrato, Broni, Bari), to shipbuilding and repair activities (Monfalcone, Trieste, La Spezia, Genova) and soil contamination (Biancavilla in Sicily).

Conclusions: Asbestos pollution outside the workplace contributes significantly to the burden of asbestos-related diseases, suggesting the need to prevent exposures and to discuss how to deal with compensation rights for malignant mesothelioma cases induced by non-occupational exposure to asbestos.

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Occupational exposures and lung cancer risk among Minnesota taconite mining workers. E.M. Allen, B.H. Alexander, R.F. MacLehose, et al. 2015;72(9):633-9. PubMed · Publisher · Free full text

Abstract

Objective: To examine the association between employment duration, elongate mineral particle (EMP) exposure, silica exposure and the risk of lung cancer in the taconite mining industry.

Methods: We conducted a nested case-control study of lung cancer within a cohort of Minnesota taconite iron mining workers employed by any of the mining companies in operation in 1983. Lung cancer cases were identified by vital records and cancer registry data through 2010. Two age-matched controls were selected from risk sets of cohort members alive and lung cancer free at the time of case diagnosis. Calendar time-specific exposure estimates were made for every job and were used to estimate workers' cumulative exposures. ORs and 95% CIs were estimated using conditional logistic regression. We evaluated total lung cancer risk and risk of histological subtype by total work duration and by cumulative EMP, and silica exposure by quartile of the exposure distribution.

Results: A total of 1706 cases and 3381 controls were included in the analysis. After adjusting for work in haematite mining, asbestos exposure and sex, the OR for total duration of employment was 0.99 (95% CI 0.96 to 1.01). The ORs for quartile 4 versus 1 of EMP and silica exposure were 0.82 (95% CI 0.57 to 1.19) and 0.97 (95% CI 0.70 to 1.35), respectively. The risk of each histological subtype of lung cancer did not change with increasing exposure.

Conclusions: This study suggests that the estimated taconite mining exposures do not increase the risk of developing lung cancer.

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A comparison of exposure assessment approaches: lung cancer and occupational asbestos exposure in a population-based case-control study. J.S. Hardt, R. Vermeulen, S. Peters, et al. 2014;71(4):282-8. PubMed · Publisher

Abstract

Objectives: In attempts to overcome the limitations of self-reported data in occupational health research, job-exposure matrices, which assign exposure by occupation, have emerged as an objective approach for assessing occupational exposures. On the basis of a lung cancer case-control study conducted in the Greater Toronto Area, 1997-2002, assessment of occupational exposure to asbestos was compared using self-reports and a general population job-exposure matrix (DOM-JEM).

Methods: Cases and frequency matched controls provided life-time job histories and self-reported exposures to potential lung carcinogens including asbestos through a detailed questionnaire. Exposure to asbestos was also assigned to each job by linking occupational histories with DOM-JEM. Agreement in classification of exposed and unexposed jobs according to self-reports and DOM-JEM was evaluated using Cohen's κ. Risks for lung cancer were estimated using unconditional logistic regression for each exposure assessment approach.

Results: The prevalence of occupational asbestos exposure was greater when based on DOM-JEM than when based on self-reports. Agreement in classifying exposure to jobs between the two assessment approaches was poor. The risk of lung cancer was not elevated among workers who self-reported asbestos exposure, whereas workers considered exposed on the basis of DOM-JEM were almost twice as likely as unexposed workers to be diagnosed with lung cancer (OR 1.9, 95% CI 1.3 to 2.7).

Conclusions: It is generally assumed by epidemiologists that self-reported exposure assessments result in inflated risk estimates. In this study, self-reports found no association with a well-established risk factor, whereas a high-quality job-exposure matrix revealed relative risk estimates that are more consistent with previous findings.
Analysing health data from rare occupational cohorts. T.F. Bateson. 2014;71(11):742-3. Comment PubMed · Publisher
Cancer incidence among firefighters: 45 years of follow-up in five Nordic countries. E. Pukkala, J.I. Martinsen, E. Weiderpass, et al. 2014;71(6):398-404. PubMed · Publisher

Abstract

Objectives: Firefighters are potentially exposed to a wide range of known and suspected carcinogens through their work. The objectives of this study were to examine the patterns of cancer among Nordic firefighters, and to compare them with the results from previous studies.

Methods: Data for this study were drawn from a linkage between the census data for 15 million people from the five Nordic countries and their cancer registries for the period 1961-2005. SIR analyses were conducted with the cancer incidence rates for the entire national study populations used as reference rates.

Results: A total of 16 422 male firefighters were included in the final cohort. A moderate excess risk was seen for all cancer sites combined, (SIR=1.06, 95% CI 1.02 to 1.11). There were statistically significant excesses in the age category of 30-49 years in prostate cancer (SIR=2.59, 95% CI 1.34 to 4.52) and skin melanoma (SIR=1.62, 95% CI 1.14 to 2.23), while there was almost no excess in the older ages. By contrast, an increased risk, mainly in ages of 70 years and higher, was observed for non-melanoma skin cancer (SIR=1.40, 95% CI 1.10 to 1.76), multiple myeloma (SIR=1.69, 95% CI 1.08 to 2.51), adenocarcinoma of the lung (SIR=1.90, 95% CI 1.34 to 2.62), and mesothelioma (SIR=2.59, 95% CI 1.24 to 4.77). By contrast with earlier studies, the incidence of testicular cancer was decreased (SIR=0.51, 95% CI 0.23 to 0.98).

Conclusions: Some of these associations have been observed previously, and potential exposure to polycyclic aromatic hydrocarbons, asbestos and shift work involving disruption of circadian rhythms may partly explain these results.
Examining the association of lung cancer and highly correlated fibre size-specific asbestos exposures with a hierarchical Bayesian model. G.B. Hamra, D. Loomis, J. Dement. 2014;71(5):353-7. PubMed · Publisher

Abstract

Background: Asbestos is a known carcinogen. However, little is known about the differential effects of size-specific asbestos fibres. Previous research has examined the relationship with lung cancer of each fibre group in the absence of others. Attempts to model all fibre groups within a single regression model have failed due to high correlations across fibre size groups.

Methods: We compare results from frequentist models for individual fibre size groups, and a hierarchical Bayesian model that included all fibre groups to estimate the relationship of size-specific asbestos fibre groups to lung cancer mortality. The hierarchical model assumes partial exchangeability of the effects of size-specific asbestos fibre groups to lung cancer, and is capable of handling the strong correlation of the exposure data.

Results: When fibre groups are modelled independently with a frequentist model, there appears to be an increase in the dose-response with increasing fibre size. However, when subject to a hierarchical structure, this trend vanishes, and the effects of distinct fibre groups appear largely similar.

Conclusions: This is the first occasion where distinct asbestos fibre groups have been assessed in a single regression model; however, even the use of a hierarchical modelling structure does not appear to overcome all the statistical fluctuations arising from the high correlations across fibre groups. We believe these results should be compared with other occupational cohorts with similar fibre group information. Finally, results for the smallest fibre group may be suggestive of a carcinogenic potential for nanofibres.
Exposure to chlorinated solvents and lung cancer: results of the ICARE study. F. Mattei, F. Guida, M. Matrat, et al. 2014;71(10):681-9. PubMed · Publisher

Abstract

Objective: To investigate the role of occupational exposure to chlorinated solvents in lung cancer aetiology.

Methods: ICARE (Investigation of occupational and environmental CAuses of REspiratory cancers) is a French, multicentre, population-based, case-control study. Information on the lifelong work history of 2926 cases and 3555 controls was collected using standardised questionnaires. Occupational exposures were assessed using job-exposure matrices for five chlorinated solvents. Solvents were studied separately and in combinations. ORs were computed using unconditional logistic regression models adjusted for classic risk factors, including a history of cigarette smoking and exposure to asbestos. Adjustment for socioeconomic status (SES) was also made.

Results: After adjustment for exposure to asbestos, we observed a positive, statistically significant association with lung cancer for men and women exposed to a combination of perchloroethylene (PCE), trichloroethylene and dichloromethane (DCM). Further adjustment for SES slightly decreased this association. In contrast, no statistically significant associations were found for other solvent combinations.

Conclusions: These results suggest that exposure to PCE may constitute a risk factor for lung cancer, especially among women, who seem to have a higher prevalence of exposure than men.

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Exposure to chrysotile mining dust and digestive cancer mortality in a Chinese miner/miller cohort. S. Lin, X. Wang, E. Yano, et al. 2014;71(5):323-8. PubMed · Publisher

Abstract

Objectives: To examine mortality from digestive cancers in a Chinese miner cohort and to explore the exposure-response relationship between chrysotile mining dust and site-specific digestive cancers.

Methods: A cohort of 1539 asbestos miners was followed for 26 years. Information on vital status and death causes was collected from personnel records and hospitals. Underlying causes of death from cancers were determined by combination of clinical manifestations and pathological confirmation. Individual cumulative dust exposures were estimated based on periodic dust measurements of different workshops, individuals' job title and employment duration, and treated as a time-dependent variable. Standardised mortality ratios (SMR) were calculated according to Chinese national data and stratified by exposure (levels 1-3, from low to high). Cox proportional hazard models were constructed to estimate HRs in relation to cumulative exposure with adjustment of smoking.

Results: Fifty-one deaths from digestive cancers were identified in the cohort, giving an SMR of 1.45 (95% CI 1.10 to 1.90). There was a clear exposure-response relationship between asbestos dust exposure and mortality from stomach cancer, with SMR of 2.39 (95% CI 1.02 to 5.60) and 6.49 (2.77 to 15.20) at exposure levels 2 and 3, respectively. The clear relationship remained in multivariate analysis, in which workers at the highest exposure level had HRs of 12.23 (95% CI 8.74 to 17.12). In addition, excess mortality from oesophageal and liver cancers was also observed at high exposure levels.

Conclusions: This study provides additional evidence for the association between exposure to chrysotile mining dust and excess mortality from digestive cancers, particularly stomach cancer.
Firefighters and cancer: where are we and where to now?. L. Fritschi, D.C. Glass. 2014;71(8):525-6. Comment PubMed · Publisher

Summary

This commissioned commentary discussed two recently published cancer incidence cohort studies of firefighters. One used employment records from three US cities linked with cancer and death registries. The other drew firefighters from census data in five Nordic countries linked with national cancer registries. Both found small but statistically significant increases in all cancers (SIR 1.10, 95% CI 1.07 to 1.13, in the US study; 1.06, 95% CI 1.02 to 1.11, in the Nordic study). Both also found an increase in mesothelioma: SIR 2.29 (95% CI 1.60 to 3.19) in the US study and 1.55 (95% CI 0.90 to 2.48) in the Nordic study. The authors attributed this likely to asbestos exposure when buildings burn and during clean-up, and perhaps to asbestos protective gear formerly worn by firefighters. They noted that asbestos remaining in old buildings will continue to expose firefighters. Both cohorts showed decreased testicular cancer risk, which the authors suggested may be chance. Neither showed the increased non-Hodgkin lymphoma risk seen in earlier meta-analyses. Both showed increased prostate cancer and melanoma. The authors related inconsistencies to differing and changing exposures, since no study had assessed individual exposures. They recommended protective clothing and respiratory protection and avoiding skin contact. They concluded that the studies strengthened evidence for increased prostate cancer and mesothelioma risks, and that prevention will depend on better exposure data.

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Genes involved in innate immunity associated with asbestos-related fibrotic changes. M.K. Kukkonen, T. Vehmas, P. Piirilä, et al. 2014;71(1):48-54. PubMed · Publisher · Free full text

Abstract

Objectives: To determine whether genetic polymorphisms in several candidate genes related to innate immunity and protease-antiprotease balance modify individual susceptibility to develop asbestos-related fibrotic pleuropulmonary changes.

Methods: Sixteen polymorphisms from nine genes (NLRP3, CARD8, TNF, TGFB1, GC, MMP1, MMP9, MMP12 and TIMP2) were genotyped from 951 Finnish asbestos-exposed workers. The genotype/haplotype data were compared to signs of fibrosis and pleural thickenings using linear and logistic regression analysis adjusted for potential confounders.

Results: A functional polymorphism (Q705K; rs35829419) in the NLRP3 gene was associated with interstitial lung fibrosis (p=0.013), and the TGFB1 rs2241718 SNP with visceral pleural fibrosis (VPF) (p=0.044). In stratified analysis, the carriage of at least one NLRP3 variant allele conferred a 2.5-fold increased risk for pathological interstitial lung fibrosis (OR 2.44, 95% CI 0.97 to 6.14). Conversely, the carriage of at least one TGFB1 rs2241718 variant allele protected against VPF (OR 0.62, 95% CI 0.39 to 0.98). The TIMP2 rs2277698 SNP and a haplotype consisting of the TGFB1 rs1800469 and rs1800470 SNPs were associated with the degree of pleural thickening calcification (p=0.037 and p=0.035), and the CARD8 rs2043211 SNP with the greatest thickness of pleural plaques (p=0.015).

Conclusions: Our results support the hypothesis that the NLRP3 inflammasome is important in the development of fibrotic lung disease by associating the NLRP3 rs35829419 variant allele with increased risk of asbestos-related interstitial lung fibrosis, and the TGFB1 rs2241718 variant allele with decreased risk of asbestos-related VPF. Polymorphisms in CARD8 and TIMP2 are proposed to modify the development and/or calcification of pleural thickenings.
Inter-reader agreement in HRCT detection of pleural plaques and asbestosis in participants with previous occupational exposure to asbestos. F. Laurent, C. Paris, G.R. Ferretti, et al. 2014;71(12):865-70. PubMed · Publisher

Abstract

Objectives: To investigate inter-reader agreement for the detection of pleural and parenchymal abnormalities using CT in a large cross-sectional study comprising information on individual cumulative exposure to asbestos.

Methods: The project was approved by the hospital ethics committee, and all patients received information on the study and gave their written informed consent. In 5511 CT scans performed in a cohort of retired workers previously exposed to asbestos and volunteering to participate in a multiregional survey programme (Asbestos Related Diseases Cohort, ARDCO), double randomised standardised readings, triple in case of disagreement, were performed by seven trained expert radiologists specialised in thoracic imaging and blind to the initial interpretation. Inter-reader agreement was evaluated by calculating the κ-weighted coefficient between pairs of expert readers and results of routine practice and final diagnosis after expert reading.

Results: κ-Weighted coefficients between trained experts ranged from 0.28 to 0.52 (fair to good), 0.59 to 0.86 (good to excellent) and 0.11 to 0.66 (poor to good) for the diagnosis of asbestosis, pleural plaques and fibrosis of the visceral pleura, respectively. κ-Weighted coefficients between results of routine practice and final diagnosis after expert reading were 0.13 (poor), 0.53 (moderate) and 0.11 (poor) for the diagnosis of asbestosis, pleural plaques and fibrosis of the visceral pleura, respectively.

Conclusions: Interpretation of benign asbestos-related thoracic abnormalities requires standardisation of the reading and trained readers, particularly for participants asking for compensation, and with a view to the longitudinal survey of asbestos-exposed workers.

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Mortality and cancer incidence in a pooled cohort of US firefighters from San Francisco, Chicago and Philadelphia (1950-2009). R.D. Daniels, T.L. Kubale, J.H. Yiin, et al. 2014;71(6):388-97. PubMed · Publisher · Free full text

Abstract

Objectives: To examine mortality patterns and cancer incidence in a pooled cohort of 29 993 US career firefighters employed since 1950 and followed through 2009.

Methods: Mortality and cancer incidence were evaluated by life table methods with the US population referent. Standardised mortality (SMR) and incidence (SIR) ratios were determined for 92 causes of death and 41 cancer incidence groupings. Analyses focused on 15 outcomes of a priori interest. Sensitivity analyses were conducted to examine the potential for significant bias.

Results: Person-years at risk totalled 858 938 and 403 152 for mortality and incidence analyses, respectively. All-cause mortality was at expectation (SMR=0.99, 95% CI 0.97 to 1.01, n=12 028). There was excess cancer mortality (SMR=1.14, 95% CI 1.10 to 1.18, n=3285) and incidence (SIR=1.09, 95% CI 1.06 to 1.12, n=4461) comprised mainly of digestive (SMR=1.26, 95% CI 1.18 to 1.34, n=928; SIR=1.17, 95% CI 1.10 to 1.25, n=930) and respiratory (SMR=1.10, 95% CI 1.04 to 1.17, n=1096; SIR=1.16, 95% CI 1.08 to 1.24, n=813) cancers. Consistent with previous reports, modest elevations were observed in several solid cancers; however, evidence of excess lymphatic or haematopoietic cancers was lacking. This study is the first to report excess malignant mesothelioma (SMR=2.00, 95% CI 1.03 to 3.49, n=12; SIR=2.29, 95% CI 1.60 to 3.19, n=35) among US firefighters. Results appeared robust under differing assumptions and analytic techniques.

Conclusions: Our results provide evidence of a relation between firefighting and cancer. The new finding of excess malignant mesothelioma is noteworthy, given that asbestos exposure is a known hazard of firefighting.
Mortality experience among Minnesota taconite mining industry workers. E.M. Allen, B.H. Alexander, R.F. MacLehose, et al. 2014;71(11):744-9. PubMed · Publisher

Abstract

Objective: To evaluate the mortality experience of Minnesota taconite mining industry workers.

Methods: Mortality was evaluated between 1960 and 2010 in a cohort of Minnesota taconite mining workers employed by any of the seven companies in operation in 1983. Standardised mortality ratios (SMR) were estimated by comparing observed deaths in the cohort with expected frequencies in the Minnesota population. Standardised rate ratios (SRR) were estimated using an internal analysis to compare mortality by employment duration.

Results: The cohort included 31,067 workers with at least 1 year of documented employment. Among those, there were 9094 deaths, of which 949 were from lung cancer, and 30 from mesothelioma. Mortality from all causes was greater than expected in the Minnesota population (SMR=1.04, 95% CI 1.02 to 1.04). Mortality from lung cancer and mesothelioma was higher than expected with SMRs of 1.16 for lung cancer (95% CI 1.09 to 1.23) and 2.77 for mesothelioma (95% CI 1.87 to 3.96). Other elevated SMRs included those for cardiovascular disease (SMR=1.10, 95% CI 1.06 to 1.14), specifically for hypertensive heart disease (SMR=1.81, 95% CI 1.39 to 2.33) and ischemic heart disease (SMR=1.11, 95% CI 1.07 to 1.16). Results of the SRR analysis did not show variation in risk by duration of employment.

Conclusions: This study provides evidence that taconite workers may be at increased risk for mortality from lung cancer, mesothelioma, and some cardiovascular disease. Occupational exposures during taconite mining operations may be associated with these increased risks, but non-occupational exposures may also be important contributors.

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A worldwide ban on asbestos production and use: some recent progress, but more still to be done. M.R. Sim. 2013;70(1):1-2. Editorial PubMed · Publisher

Summary

In this commissioned editorial, the author reviewed recent progress towards a worldwide ban on asbestos production and use. He noted that the 1960 paper by Wagner et al linking crocidolite work with mesothelioma in South Africa had contributed to large reductions in asbestos mining and exposure, mainly in developed countries. By contrast, newly industrialising countries such as Brazil, China and India continued to produce, import and use large amounts of chrysotile. He summarised recent evidence. In the UK, risk of mesothelioma had shifted from mining and manufacturing workers to carpenters, plumbers and other tradespeople. Fibre length was linked to lung cancer risk among chrysotile-exposed workers. Non-occupational exposure accounted for a growing proportion of disease. The International Agency for Research on Cancer had concluded that all forms of asbestos cause cancer in humans, with the strongest evidence for mesothelioma and cancer of the lung and larynx. In 2012 the International Commission on Occupational Health and the Joint Policy Committee of the Societies of Epidemiology called for bans. In September 2012 Canada dropped its opposition to listing chrysotile under the Rotterdam Convention, Quebec cancelled a $58 million loan to the last Canadian chrysotile mine, and the Chrysotile Institute closed. The author rejected the argument that asbestos can be used safely and concluded that much remained to be done.

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Carving of non-asbestiform tremolite and the risk of lung cancer: a follow-up mortality study in a historical nephrite processing cohort. H.Y. Yang, R.H. Shie, P.C. Chen. 2013;70(12):852-7. PubMed · Publisher · Free full text

Abstract

Objectives: The health risks associated with exposure to non-asbestiform asbestos minerals, including nephrite, are unclear. In 1965 nephrite processing began in the town of Fengtian in Taiwan, and the majority of inhabitants were involved in the industry from 1970 until 1980. The objectives of this study were to examine lung cancer deaths and assess the carcinogenic effects of nephrite carving.

Methods: We studied mortality due to lung cancer (ICD-9 code 162 for cancers of the trachea, bronchus and lung) from 1979 to 2011. We calculated the standardised mortality ratio (SMR) for lung cancer using the age- and sex-specific cancer mortality rates in eastern Taiwan as the standard rates. Air samples, bulk samples and a surface sample were analysed.

Results: Nephrite is a non-asbestiform asbestos mineral composed of microcrystalline tremolite. During nephrite processing, in personal air samples the average concentration of elongated mineral particles with the morphological characteristics of asbestos fibres was 1.4 f/cm(3), with rough grinding generating the highest concentrations (4.7 f/cm(3)). Transmission electron microscopy (TEM) confirmed that the air samples contained intact asbestiform tremolite fibres. The ambient air samples and the wipe sample indicated paraoccupational contamination. The crude mortality rates for lung cancer were higher in Fengtian than in Taiwan for all age groups and both genders. The SMR for lung cancer was 1.28 (95% CI 1.12 to 1.45).

Conclusions: Nephrite carving may increase the risk of lung cancer. Appropriate medical monitoring is warranted for workers who are exposed to similar materials.
Comparison of exposure assessment methods in a lung cancer case-control study: performance of a lifelong task-based questionnaire for asbestos and PAHs. E. Bourgkard, P. Wild, M. Gonzalez, et al. 2013;70(12):884-91. PubMed · Publisher

Abstract

Objective: To describe the performance of a lifelong task-based questionnaire (TBQ) in estimating exposures compared with other approaches in the context of a case-control study.

Methods: A sample of 93 subjects was randomly selected from a lung cancer case-control study corresponding to 497 jobs. For each job, exposure assessments for asbestos and polycyclic aromatic hydrocarbons (PAHs) were obtained by expertise (TBQ expertise) and by algorithm using the TBQ (TBQ algorithm) as well as by expert appraisals based on all available occupational data (REFERENCE expertise) considered to be the gold standard. Additionally, a Job Exposure Matrix (JEM)-based evaluation for asbestos was also obtained. On the 497 jobs, the various evaluations were contrasted using Cohen's κ coefficient of agreement. Additionally, on the total case-control population, the asbestos dose-response relationship based on the TBQ algorithm was compared with the JEM-based assessment.

Results: Regarding asbestos, the TBQ-exposure estimates agreed well with the REFERENCE estimate (TBQ expertise: level-weighted κ (lwk)=0.68; TBQ algorithm: lwk=0.61) but less so with the JEM estimate (TBQ expertise: lwk=0.31; TBQ algorithm: lwk=0.26). Regarding PAHs, the agreements between REFERENCE expertise and TBQ were less good (TBQ expertise: lwk=0.43; TBQ algorithm: lwk=0.36). In the case-control study analysis, the dose-response relationship between lung cancer and cumulative asbestos based on the JEM is less steep than with the TBQ-algorithm exposure assessment and statistically non-significant.

Conclusions: Asbestos-exposure estimates based on the TBQ were consistent with the REFERENCE expertise and yielded a steeper dose-response relationship than the JEM. For PAHs, results were less clear.
Longitudinal decline in lung function in former asbestos exposed workers. E. Algranti, E.M. Mendonça, E. Hnizdo, et al. 2013;70(1):15-21. PubMed · Publisher

Abstract

Background: This study was designed to assess the effect of asbestos exposure on longitudinal lung function decline.

Methods: A group of 502 former asbestos-cement workers with at least two spirometry tests 4 years apart. Repeated evaluations included respiratory symptoms questionnaire, spirometry and chest imaging. Asbestos exposure was ascertained as years of exposure, an index of cumulative exposure and latency time. The mixed effects model was used to evaluate the effect of exposure on the level and rate of change in forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC).

Results: Mean age at entry was 51 (SD 9.9) years, mean latency time 25.6 (SD 10.0) years, mean follow-up time 9.1 (SD 2.8) years and mean number of spirometry tests 3.5. The FEV(1) level was significantly related to pack-years of smoking at entry and during the follow-up, the index of cumulative asbestos exposure at entry, and the presence of asbestosis at follow-up. The FVC level was significantly related to pack-years of smoking during the follow-up, cumulative asbestos exposure at entry, asbestosis and pleural thickening at follow-up, and body mass index at entry. Asbestos exposure was not associated with increasing rates of FEV(1) and FVC decline. However, FEV(1) regression slopes with age, estimated by terciles of cumulative exposure, showed significant differences. Combined effects of smoking and exposure conferred further acceleration in lung function decline.

Conclusions: Occupational exposure in asbestos-cement industry was a risk factor for increased lung function decline. The effect seems to be mostly concentrated during the working period. Smoking and exposure had synergic effects.
Occupational asbestos exposure is associated with pharyngeal squamous cell carcinoma in men from the greater Boston area. S.M. Langevin, M.H. O'Sullivan, J.L. Valerio, et al. 2013;70(12):858-63. PubMed · Publisher · Free full text

Abstract

Objectives: Asbestos is the name given to a group of naturally occurring silicate mineral fibres that were widely used in industry during the 20th century due to their desirable physical properties. Although use in the USA has fallen over the last three decades, significant exposure in the developing world continues and the burden of disease is considerable. Asbestos is a known risk factor for several malignant diseases, including lung cancer and mesothelioma, and has more recently been implicated in pharyngeal and laryngeal cancer. However, studies of asbestos and cancers of the larynx or pharynx with adequate sample size that control for major head and neck squamous cell carcinoma (HNSCC) risk factors remain relatively sparse.

Methods: We report findings from a case-control study of 674 incident male HNSCC cases from the greater Boston region and 857 population-based male controls, matched on age (±3 years), sex, and town or neighbourhood of residence. Multivariable logistic regression was used to assess the association between occupational asbestos exposure and HNSCC by primary tumour site.

Results: 190 cases (28.2%) and 203 controls (23.7%) reported occupational exposure to asbestos. Occupational asbestos exposure was associated with elevated risk of pharyngeal carcinoma in men (OR 1.41, 95% CI 1.01 to 1.97), adjusted for age, race, smoking, alcohol consumption, education, income and HPV16 serology, with borderline increasing risk for each decade in the exposed occupation (OR 1.10, 95% CI 0.99 to 1.23).

Conclusions: These observations are consistent with mounting evidence that asbestos is a risk factor for pharyngeal cancer.
Pleural mesothelioma in relation to meteorological conditions and residential distance from an industrial source of asbestos. J. Tarrés, C. Albertí, X. Martínez-Artés, et al. 2013;70(8):588-90. PubMed · Publisher

Abstract

Objectives: Few studies have focused on pleural mesothelioma and environmental exposure in individuals residing around an industrial source of asbestos. The aim of this study is to determine whether residential distance and wind conditions are related to the risk of developing pleural mesothelioma.

Methods: In this retrospective cohort study carried out in an area of Barcelona province (Catalonia, Spain), 24 environmental pleural mesothelioma cases were diagnosed between 2000 and 2009. We calculated the age-standardised incidence rate ratios of developing this disease in the population studied, taking into account the residential distance from the plant. For cases living within a 500-m radius of the plant, the geographical location in relation to the factory was also assessed.

Results: The incidence rate of environmental pleural mesothelioma was higher in the population living within 500 m of the plant than in those living in a radius of 500-2000 m and much higher than those living at 2000-10 000 m. The highest incidence rate ratio for pleural mesothelioma (161.9) was found in the southeast quadrant of the 500-m area, coinciding with the predominant wind direction.

Conclusions: Residential distance from an industrial source of asbestos and local wind conditions have a considerable impact on the risk of developing environmental pleural mesothelioma.
A proposed threshold exposure for airborne asbestos. J.H. Lange, G. Mastrangelo, L. Cegolon. 2012;69(3):227-8. Letter · Comment PubMed · Publisher
Associations between radiographic findings and spirometry in a community exposed to Libby amphibole. T.C. Larson, M. Lewin, E.B. Gottschall, et al. 2012;69(5):361-6. PubMed · Publisher

Abstract

Background: Among asbestos-exposed individuals, abnormal spirometry is usually associated with parenchymal abnormalities or diffuse pleural thickening. Localised pleural thickening (LPT), the most common abnormality associated with asbestos exposure, is typically thought to be a marker of exposure with little clinical consequence. Our objective was to determine if abnormal spirometry is associated with LPT independent of other abnormalities, using data from community-based screening conducted in Libby, Montana.

Methods: Subjects were a subset of screening participants comprising persons with interpretable spirometry and chest radiograph results (n=6475). Chest radiographs were independently evaluated by two or three B readers, and participants were classified by mutually exclusive categories of spirometry outcome: normal, restriction, obstruction or mixed defect.

Results: Restrictive spirometry was strongly associated with parenchymal abnormalities (OR 2.9; 95% CI 1.4 to 6.0) and diffuse pleural thickening (OR 4.1; 95% CI 2.1 to 7.8). Controlling for the presence of these abnormalities as well as age, smoking status and other covariates, restrictive spirometry was also associated with LPT (OR 1.4; 95% CI 1.1 to 1.8). The risk of restrictive spirometric findings correlated with the severity of LPT.

Conclusions: In this large community-based screening cohort, restrictive spirometry is significantly associated with LPT, indicating that this abnormality may result in lung function impairment. Physicians treating patients exposed to Libby amphibole should be aware that LPT may have functional consequences.
Cardiovascular disease mortality among British asbestos workers (1971-2005). A.H. Harding, A. Darnton, J. Osman. 2012;69(6):417-21. PubMed · Publisher

Abstract

Objectives: Asbestos is an inflammatory agent, and there is evidence that inflammatory processes are involved in the development of cardiovascular disease. Whether asbestos is a risk factor for cardiovascular disease has not been established. The objective of this study was to investigate cardiovascular disease mortality in a large cohort of workers occupationally exposed to asbestos.

Methods: Cardiovascular disease mortality in a cohort of 98,912 asbestos workers, with median follow-up of 19 years, was analysed. Unadjusted and smoking-adjusted standardised mortality ratios (SMRs) were calculated. The association between indicators of asbestos exposure and mortality was analysed with Poisson regression models, for deaths occurring during the period 1971-2005.

Results: Altogether 15,557 deaths from all causes, 1053 deaths from cerebrovascular disease and 4185 deaths from ischaemic heart disease (IHD) occurred during follow-up. There was statistically significant excess mortality from cerebrovascular disease (SMR: men 1.63, women 2.04) and IHD (SMR: men 1.39, women 1.89). Job and birth cohort were associated with the risk of cerebrovascular and IHD mortality in the Poisson regression model including sex, age, smoking status, job, cohort and duration of exposure. For IHD only, duration of exposure was also statistically significant in this model.

Conclusions: Cerebrovascular and IHD mortality was significantly higher among these asbestos workers than in the general population and within the cohort mortality was associated with indicators of asbestos exposure. These findings provide some evidence that occupational exposure to asbestos was associated with cardiovascular disease mortality in this group of workers.
Comparison of expert and job-exposure matrix-based retrospective exposure assessment of occupational carcinogens in The Netherlands Cohort Study. N.S. Offermans, R. Vermeulen, A. Burdorf, et al. 2012;69(10):745-51. PubMed · Publisher

Abstract

Objectives: Reliable retrospective exposure assessment continues to be a challenge in most population-based studies. Several methodologies exist for estimating exposures retrospectively, of which case-by-case expert assessment and job-exposure matrices (JEMs) are commonly used. This study evaluated the reliability of exposure estimates for selected carcinogens obtained through three JEMs by comparing the estimates with case-by-case expert assessment within the Netherlands Cohort Study (NLCS).

Methods: The NLCS includes 58,279 men aged 55-69 years at enrolment in 1986. For a subcohort of these men (n=1630), expert assessment is available for exposure to asbestos, polycyclic aromatic hydrocarbons (PAHs) and welding fumes. Reliability of the different JEMs (DOMJEM (asbestos, PAHs), FINJEM (asbestos, PAHs and welding fumes) and Asbestos JEM (asbestos) was determined by assessing the agreement between these JEMs and the expert assessment.

Results: Expert assessment revealed the lowest prevalence of exposure for all three exposures (asbestos 9.3%; PAHs 5.3%; welding fumes 11.7%). The DOMJEM showed the highest level of agreement with the expert assessment for asbestos and PAHs (κs=0.29 and 0.42, respectively), closely followed by the FINJEM. For welding fumes, concordance between the expert assessment and FINJEM was high (κ=0.70). The Asbestos JEM showed poor agreement with the expert asbestos assessment (κ=0.10).

Conclusions: This study shows case-by-case expert assessment to result in the lowest prevalence of occupational exposure in the NLCS. Furthermore, the DOMJEM and FINJEM proved to be rather similar in agreement when compared with the expert assessment. The Asbestos JEM appeared to be less appropriate for use in the NLCS.
Estimation of benefit of prevention of occupational cancer for comparative risk assessment: methods and examples. L.J. Lee, Y.Y. Chang, S.H. Liou, et al. 2012;69(8):582-6. PubMed · Publisher · Free full text

Abstract

Objectives: To quantify the life years gained and financial savings by preventing a case of occupational cancer.

Methods: The authors retrieved data from the Taiwan Cancer Registry and linked them with the National Mortality Registry to estimate the survival functions for major occupational cancers: lung, pleural mesothelioma, urinary bladder and leukaemia. Assuming a constant excess hazard for each type of cancer, the authors extrapolated lifetime survival functions by the Monte Carlo method. For each patient with cancer, the authors simulated an age- and gender-matched person without cancer based on vital statistics of Taiwan to estimate life expectancy and expected years of life lost (EYLL). By using the reimbursement data from the National Health Insurance Research Database, the authors calculated the average monthly healthcare expenditures, which were summed to estimate the lifetime healthcare expenditures after adjusting for the corresponding monthly survival probability.

Results: A total of 51,408, 136, 12,891 and 5285 new cases of lung, pleural mesothelioma, bladder and leukaemia cancers, respectively, were identified during 1997-2005 and followed until the end of 2007. The EYLL was predicted to be 13.7±0.1, 18.9±0.7, 4.7±0.3 and 19.4±0.5 years for these cancers, respectively, and the lifetime healthcare expenditures with a 3% annual discount were predicted to be US$22,359, US$14,900, US$51,987 and US$59,741, respectively.

Conclusions: The burden of these occupational cancers, in terms of EYLL and lifetime healthcare expenditures, was substantial. Such estimates may provide useful empirical evidence for comparative risk assessment that can be applied in health policy-making and clinical decision-making.
Exposure-response relationship between chrysotile exposure and mortality from lung cancer and asbestosis. Q. Deng, X. Wang, M. Wang, et al. 2012;69(2):81-6. PubMed · Publisher

Abstract

Objectives: To describe mortality in workers exposed to chrysotile asbestos, and determine exposure-response relationships between asbestos exposure and mortality from lung cancer and asbestosis by fitting and comparing different models.

Methods: A prospective cohort consisting of 586 workers in an asbestos textile factory was followed from 1 January 1972 to 31 December 2006. A structured questionnaire was administered to collect personal information and exposure data. Paired concentration samples measured in the workshops were used to convert dust concentrations to fibre concentrations. Individual cumulative asbestos exposure was estimated as the product of fibre concentrations and duration of employment in each job and expressed as fibre-years/ml. The vital status of cohort members was followed annually. Poisson regression analysis was applied to fit log-linear, log-quadratic, power, additive relative risk and categorical models to estimate exposure-response relationships between cumulative fibre exposure and mortality from lung cancer and asbestosis.

Results: Of the 226 deaths (14.6 per 1000 person-years) over the 35-year follow-up, 51 were from lung cancer (3.29 per 1000 person-years) and 37 from asbestosis (2.39 per 1000 person-years). A significant exposure-response relationships with either lung cancer or asbestosis (p<0.001) was observed in the final model. The power model with lagged 10 years was found to be the best model of those evaluated for both lung cancer (β coefficient=0.53) and asbestosis (β coefficient=0.63).

Conclusions: The study confirmed strong associations between exposure to chrysotile asbestos and lung cancer and asbestosis, in which clear exposure-response relationships were observed.
Increased lung cancer mortality among chrysotile asbestos textile workers is more strongly associated with exposure to long thin fibres. D. Loomis, J.M. Dement, L. Elliott, et al. 2012;69(8):564-8. PubMed · Publisher

Abstract

Background: Animal data and physical models suggest that the carcinogenicity of asbestos fibres is related to their size and shape.

Objectives: To investigate the influence of fibre length and diameter on lung cancer risk in workers at asbestos textile mills in North Carolina and South Carolina, USA.

Methods: Men and women (n=6136) who worked ≥30 days in production and were employed between 1940 and 1973 were enumerated and followed for vital status through 2003. A matrix of fibre size-specific exposure estimates was constructed using determinations of fibre numbers and dimensions through analysis of 160 historical dust samples by transmission electron microscopy. Associations of lung cancer mortality with metrics of fibre exposure were estimated by Poisson regression with adjustment for age, sex, race and calendar year.

Results: Exposure to fibres throughout the range of length and diameter was significantly associated with increased risk of lung cancer. Models for fibres >5 μm long and <0.25 μm in diameter provided the best fit to the data, while fibres 5-10 μm long and <0.25 μm in diameter were associated most strongly with lung cancer mortality (log rate about 4% per IQR, p<0.001). When indicators of mean fibre length and diameter were modelled simultaneously, lung cancer risk increased as fibre length increased and diameter decreased.

Conclusions: The findings support the hypothesis that the occurrence of lung cancer is associated most strongly with exposure to long thin asbestos fibres. The relationship of cancer risk and fibre dimensions should be examined in cohorts exposed to other types of fibres.
Lung cancer incidence in Canadian petroleum workers. A.R. Schnatter, M.J. Nicolich, R.J. Lewis, et al. 2012;69(12):877-82. PubMed · Publisher

Abstract

Objectives: This study's purpose was to conduct a more in-depth analysis of the potential association between lung cancer, occupational exposures and smoking using data on cohort members from a Canadian petroleum company and refined statistical analyses.

Methods: Information on various exposures including asbestos and petroleum coke dust, as well as job type and operating segment were collected via manual and computerised company records. We performed life-table analyses, Poisson regression and restricted cubic splines to model exposure-response patterns while controlling for smoking status and age. Model diagnostics included the assessment of dispersion and offset parameters.

Results: These analyses show that lung cancer risk is strongly related to age and smoking, and to a lesser extent to province of last residence. When controlling for these covariates, there is suggestive evidence that maintenance work may also be related to lung cancer risk. Some analyses also indicate that asbestos exposure may be associated with lung cancer risk, although a clear exposure-response trend is not seen. Other exposures, including petroleum coke dust, were not strongly related to lung cancer risk, particularly when expressed as a continuous measure.

Conclusions: These data suggest that maintenance work may be associated with lung cancer incidence, although exposures to the single agents studied did not emerge as strong predictors of lung cancer incidence. Maintenance work may be a surrogate for general exposures to several agents (eg, polycyclic aromatic hydrocarbons, metals, welding fumes, radiation, etc), although these results may be affected by residual confounding due to smoking or other socio-demographic factors.
Lung cancer mortality in North Carolina and South Carolina chrysotile asbestos textile workers. L. Elliott, D. Loomis, J. Dement, et al. 2012;69(6):385-90. PubMed · Publisher

Abstract

Objectives: Studies of workers in two US cohorts of asbestos textile workers exposed to chrysotile (North Carolina (NC) and South Carolina (SC)) found increasing risk of lung cancer mortality with cumulative fibre exposure. However, the risk appeared to increase more steeply in SC, possibly due to differences in study methods. The authors conducted pooled analyses of the cohorts and investigated the exposure-disease relationship using uniform cohort inclusion criteria and statistical methods.

Methods: Workers were included after 30 days of employment in a production job during qualifying years, and vital status ascertained through 2003 (2001 for SC). Poisson regression was used to estimate the exposure-response relationship between asbestos and lung cancer, using both exponential and linear relative rate models adjusted for age, sex, race, birth cohort and decade of follow-up.

Results: The cohort included 6136 workers, contributing 218,631 person-years of observation and 3356 deaths. Cumulative exposures at the four study facilities varied considerably. The pooled relative rate for lung cancer, comparing 100 f-yr/ml to 0 f-yr/ml, was 1.11 (95% CI 1.06 to 1.16) for the combined cohort, with different effects in the NC cohort (RR=1.10, 95% CI 1.03 to 1.16) and the SC cohort (RR = 1.67, 95% CI 1.44 to 1.93).

Conclusions: Increased rates of lung cancer were significantly associated with cumulative fibre exposure overall and in both the Carolina asbestos-textile cohorts. Previously reported differences in exposure-response between the cohorts do not appear to be related to inclusion criteria or analytical methods.
Occupational exposures and risk of stomach cancer by histological type. M. Santibañez, J. Alguacil, M.G. de la Hera, et al. 2012;69(4):268-75. PubMed · Publisher

Abstract

Objective: To explore the relationship between stomach cancer (SC), by histological type, and occupations and occupational exposures.

Methods: The authors conducted a hospital-based case-control study in south-east Spain. Subjects were 399 incident histological confirmed SC cases (241 intestinal and 109 diffuse adenocarcinomas) and 455 controls frequency matched by sex, age and province of residence. Occupation was coded according to the Spanish National Classification of Occupations 1994. Occupational exposures were assessed by the FINJEM Job Exposure Matrix. ORs were estimated by unconditional logistic regression adjusting for matching variables and education, smoking, alcohol and diet.

Results: In men, statistically significant increased risk of the diffuse subtype was found for 'cooks' (OR 8.02), 'wood-processing-plant operators' (OR 8.13) and 'food and related products machine operators' (OR 5.40); for the intestinal subtype, a borderline association was found for 'miners and quarry workers' (OR men 4.22, 95% CI 0.80 to 22.14). Significant increased risk was observed between the diffuse subtype of SC and the highest level of exposure to 'pesticides' (OR(H) both sexes 10.39, 95% CI 2.51 to 43.02, p(trend)=0.02) and between the intestinal subtype and asbestos (OR(H) men 3.71, 95% CI 1.40 to 9.83, p(trend)=0.07). Restricted analyses of exposures of 15 years and longer showed significant associations between the diffuse subtype and the exposure to 'wood dust' (OR men 3.05).

Conclusions: This study supports the relationship previously suggested between SC and occupational exposure to dusty and high temperature environments. Several occupations may also increase the risk of diffuse SC but not the intestinal subtype.
Cancer incidence within a cohort occupationally exposed to asbestos: a study of dose--response relationships. B. Clin, F. Morlais, G. Launoy, et al. 2011;68(11):832-6. PubMed · Publisher

Abstract

Objectives: The aim of our study was to analyse the dose-response relationship between occupational asbestos exposure and risk of cancer.

Methods: Our study was a retrospective morbidity study based on 2024 subjects occupationally exposed to asbestos, conducted over the period 1 January 1978 to 31 December 2004. Analysis of the dose-response relationship between occupational asbestos exposure, as a time-dependant variable, and risk of cancer was performed using a Cox model. In order to account for the effect of latency, we conducted the analysis with a lag of 10 years.

Results: 285 cases of cancers were observed in our cohort. The relative risk of pleuro-peritoneal mesothelioma, lung cancer and colorectal cancer associated with asbestos exposure, adjusted for age as a time-dependant variable and for sex, was correlated with exposure intensity (or average exposure level, AEL). The risk of cancer, whatever the anatomical site, did not increase with the duration of exposure to asbestos.

Conclusion: While confirming the established relationship between asbestos exposure and pleuropulmonary and peritoneal cancers, this study also suggests a causal relationship between asbestos exposure and colorectal cancer.
Comparison of exposure assessment methods for occupational carcinogens in a multi-centre lung cancer case-control study. S. Peters, R. Vermeulen, A. Cassidy, et al. 2011;68(2):148-53. PubMed · Publisher

Abstract

Objectives: Retrospective exposure assessment remains a problematic aspect of population-based case-control studies. Different methods have been developed, including case-by-case expert assessment and job-exposure matrices (JEM). The present analyses compare exposure prevalence and risk estimates derived by different exposure assessment methods.

Methods: In the context of a case-control study conducted in seven European countries, exposure was estimated for asbestos, diesel motor emissions (DME) and crystalline silica, using three different assessment methods. First, experts assigned exposures to all reported jobs on a case-by-case basis. Second, a population-specific JEM (PSJEM) was developed using the expert assessments of controls only, and re-applied to all study subjects. Third, an independent general population JEM (GPJEM) was created by occupational exposure experts not involved in the original study, and applied to study subjects. Results from these methods were compared.

Results: There was poor to fair agreement in assigned exposure between expert assessment and the GPJEM (kappas: asbestos 0.17; DME 0.48; silica 0.38). Exposure prevalence was significantly heterogeneous (p<0.01) between countries for all three agents and assessment methods. For asbestos and DME, significant country heterogeneity in risk estimates was observed when using expert assessment. When applying the GPJEM, the heterogeneity in risk estimates for asbestos and, to some extent, silica diminished.

Conclusions: It has been previously advocated that the expert assessment approach to assign exposures based on detailed questionnaire responses provides more accurate exposure estimates than JEM-based results. However, current results demonstrated little, if any, advantage of case-by-case assessment when compared to a JEM approach.
Estimates of historical exposures by phase contrast and transmission electron microscopy for pooled exposure--response analyses of North Carolina and South Carolina, USA asbestos textile cohorts. J.M. Dement, D. Loomis, D. Richardson, et al. 2011;68(8):593-8. PubMed · Publisher

Abstract

Objectives: To develop pooled size-specific asbestos fiber exposure estimates for North Carolina and South Carolina asbestos textile plants.

Methods: Airborne sample data and prior exposure estimates by phase-contrast microscopy (PCM) for the two cohorts were reviewed and compared. Estimates by transmission electron microscopy (TEM) for 160 membrane filter samples from all plant were pooled. Poisson regression models were developed to predict bivariate diameter/length airborne fiber size distributions based on independent categorical variables for fiber diameter, fiber length, plant, and exposure zone. The model predicted bivariate diameter/length distributions were expressed as the proportion of fibers in 28 size-specific cells and these data were used to calculate PCM to TEM adjustment factors in order to estimate fiber size-specific exposures for the pooled cohort.

Results: Exposure levels in the North Carolina plants were in excess of 50 f/cc for many operations through about 1955 owing to lack of dust control measures in early years whereas levels in the South Carolina plant were generally less than 10 f/cc by about 1950. The Poisson regression models found covariates for plant department to be a stronger predictor of bivariate size proportions than plant; however, a plant effect was observed. The final Poisson models demonstrated good fit to the observed data.

Conclusions: Consistent with early studies, fiber exposures in the North Carolina plants were much higher than in South Carolina plant. Use of the predicted size-specific TEM exposures by plant and department based on the Poisson model predictions should reduce exposure.
Risk of lung cancer associated with quantitative beryllium exposure metrics within an occupational cohort. M.K. Schubauer-Berigan, J.A. Deddens, J.R. Couch, et al. 2011;68(5):354-60. PubMed · Publisher

Abstract

Objectives: Beryllium has been identified as a human carcinogen on the basis of animal and epidemiological studies. The authors recently reported updated associations between lung cancer and beryllium exposure in a large, pooled occupational cohort. The authors conducted the present study to evaluate the shape of exposure-response associations between different exposure metrics and lung cancer in this cohort, considering potential confounders (race, plant, professional and short-term work status, and exposure to other lung carcinogens).

Methods: The authors conducted Cox proportional hazards regression analyses of lung cancer risk with cumulative, mean and maximum 'daily weighted average' (DWA) exposure among 5436 workers, using age-based risk sets. Different exposure-response curves were fitted to the exposure metrics, including categorical, power, restricted cubic spline and piecewise log-linear fits.

Results: The authors found significant positive associations between lung cancer and mean (p < 0.0001) and maximum (p < 0.0001) exposure, adjusting for age, birth cohort and plant, and for cumulative (p = 0.0017) beryllium exposure, adjusting for these factors plus short-term work status and exposure to asbestos. The best-fitting models were generally categorical or piecewise log-linear, with the steepest increase in lung cancer risk between 0 and 10 μg/m(3) for both mean and maximum DWA exposure and between 0 and 200 μg/m(3)-days for cumulative DWA exposure. The estimated mean DWA beryllium exposure associated with 10(-3) excess lifetime risk based on the piecewise log-linear model is 0.033 μg/m(3).

Conclusion: This study provides evidence that lung cancer risk is elevated at levels near the current US Occupational Safety and Health Administration beryllium exposure limit of 2.0 μg/m(3) DWA for workers.
Surveillance of mesothelioma and workers' compensation in British Columbia, Canada. T.L. Kirkham, M.W. Koehoorn, C.B. McLeod, et al. 2011;68(1):30-5. PubMed · Publisher

Abstract

Objectives: To determine the rate of workers' compensation for mesothelioma cases in the Canadian province of British Columbia, examine trends in mesothelioma cases and compensation over time, and identify factors associated with compensation status for mesothelioma cases.

Methods: Mesothelioma cases in the provincial cancer registry were linked at the individual level with accepted claims for mesothelioma in the provincial workers' compensation system for the period 1970-2005.

Results: 391 of the 485 workers' compensated claims were linked (81% match rate) with a record in the cancer registry for an overall mesothelioma compensation rate of 33% over the study period and a high of 49% in the last 5 years. Compensation rates were lower for women, older (retired) as well as younger workers, and sites other than the pleura.

Conclusions: Although the workers' compensation rate for mesothelioma increased over time, the rate was much lower than anticipated for cases believed to be work-related cancers. Several key factors may significantly influence awareness by clinicians and workers of the work-relatedness of mesothelioma and of workers' compensation benefits. Regulatory agencies need to develop policies or effective notification systems to ensure that all newly diagnosed mesothelioma cases seek compensation benefits.
The two-stage clonal expansion model in occupational cancer epidemiology: results from three cohort studies. A. Zeka, R. Gore, D. Kriebel. 2011;68(8):618-24. PubMed · Publisher

Abstract

Objectives: The objective of this work was to apply the two-stage clonal expansion model, with the intention to expand the literature on epidemiological applications of the model and demonstrate the feasibility of incorporating biologically based modelling methods into the widely used retrospective cohort study.

Methods: The authors fitted the two-stage clonal expansion model model to three occupational cohort studies: (1) a cohort of textile workers exposed to asbestos and followed for lung cancer mortality; (2) a cohort of diatomaceous earth workers exposed to silica and also followed for lung cancer mortality; and (3) a cohort of automotive manufacturing workers exposed to straight metalworking fluid (MWF) and followed for larynx cancer incidence. The model allowed the authors to estimate exposure effects in three stages: cancer initiation (early effects), promotion or malignant transformation (late effects).

Results: In the first cohort, the authors found strong evidence for an early effect of asbestos on lung cancer risk. Findings from analyses of the second cohort suggested early and less evidently late effects of silica on lung cancer risk. In the MWF (third) cohort, there was only weak evidence of straight MWF exposure effects on both early and late stages. The authors also observed a late birth cohort effect on larynx cancer risk.

Conclusions: The findings for asbestos and silica were essentially confirmatory, supporting evidence for their early effects on lung cancer from a large body of literature. The effect of straight MWF on larynx cancer was less clear.
Trends in mesothelioma mortality rates in South Africa: 1995-2007. D. Kielkowski, G. Nelson, B. Bello, et al. 2011;68(7):547-9. PubMed · Publisher

Abstract

Objective: In 1984, South Africa had one of the highest mesothelioma rates in the world. The objective of this analysis was to calculate mesothelioma mortality rates in the South African population from 1995 to 2007.

Methods: Annual mortality data and midyear population estimates were used to compute mortality rates by age group and gender for each year. The WHO World Standard Population was used as the reference population to calculate age-adjusted rates. Poisson regression models were used to test for trends.

Results: In total, 2509 deaths due to mesothelioma were identified in the study period: 1920 in men and 588 in women. There were no significant trends in mesothelioma mortality rates: age-adjusted mortality rates fluctuated from 11 to 16 and from 3 to 5 per million per year for men and women, respectively.

Conclusion: These mortality rates are much lower than expected, given the historical production and use of, and high exposure to, asbestos in South Africa. Possible reasons for this are discussed, including the effect of HIV which has been instrumental in reducing the life expectancy of South Africans in the last two decades. Asbestos-exposed individuals may not live long enough to develop mesothelioma. Competing causes of death need to be taken into account when constructing models to predict mesothelioma mortality rates.
Asbestos fibre dimensions and lung cancer mortality among workers exposed to chrysotile. D. Loomis, J. Dement, D. Richardson, et al. 2010;67(9):580-4. PubMed · Publisher · Free full text

Abstract

Objectives: To estimate exposures to asbestos fibres of specific sizes among asbestos textile manufacturing workers exposed to chrysotile using data from transmission electron microscopy (TEM) and to evaluate the extent to which the risk of lung cancer varies with fibre length and diameter.

Methods: 3803 workers employed for at least 1 day between 1 January 1950 and 31 December 1973 in any of three plants in North Carolina, USA that produced asbestos textile products and followed for vital status through 31 December 2003 were included. Historical exposures to asbestos fibres were estimated from work histories and 3578 industrial hygiene measurements taken in 1935-1986. Exposure-response relationships for lung cancer were examined within the cohort using Poisson regression.

Results: Indicators of fibre length and diameter obtained by TEM were positively and significantly associated with increasing risk of lung cancer. Exposures to longer and thinner fibres tended to be most strongly associated with lung cancer, and models for these fibres fit the data best. Simultaneously modelling indicators of cumulative mean fibre length and diameter yielded a positive coefficient for fibre length and a negative coefficient for fibre diameter.

Conclusions: The results support the hypothesis that the risk of lung cancer among workers exposed to chrysotile asbestos increases with exposure to longer fibres. More research is needed to improve the characterisation of exposures by fibre size and number and to analyse the associated risks in a variety of industries and populations.
Incidence of extrapleural malignant mesothelioma and asbestos exposure, from the Italian national register. A. Marinaccio, A. Binazzi, D. Di Marzio, et al. 2010;67(11):760-5. PubMed · Publisher

Abstract

Objectives: The epidemiology of extrapleural malignant mesothelioma is rarely discussed and the risk of misdiagnosis and the very low incidence complicate the picture. This study presents data on extrapleural malignant mesothelioma from the Italian National Mesothelioma Register (ReNaM).

Methods: ReNaM works on a regional basis, searching for cases and interviewing subjects to investigate asbestos exposure. Classification and code criteria for certainty of diagnosis and exposure modalities are set by national guidelines. Between 1993 and 2004, 681 cases were collected. Incidence measures and exposure data refer to the ReNaM database. Age-standardised rates were estimated by the direct method using the Italian resident population in 2001. Correlations between the incidence of pleural and non-pleural malignant mesothelioma for the 103 Italian provinces were analysed.

Results: Standardised incidence rates (Italy, 2004, per million inhabitants) were 2.1 and 1.2 cases for the peritoneal site (in men and women, respectively), 0.2 cases for the tunica vaginalis testis, and 0.1 in the pericardial site, varying widely in different parts of the country. Mean age at diagnosis for all extrapleural malignant mesothelioma cases was 64.4 years and the men/women ratio was 1.57:1. Median latency was over 40 years for all extrapleural sites combined. The correlation between pleural and peritoneal mesothelioma was 0.71 (Pearson's r coefficient, p<0.001). Modalities of exposure to asbestos fibres were investigated for 392 cases.

Conclusions: The rarity of the disease, the low specificity of diagnosis and difficulties in identifying the modalities of asbestos exposure call for caution in discussing aetiological factors other than asbestos.
Lung cancer mortality from exposure to chrysotile asbestos and smoking: a case-control study within a cohort in China. E. Yano, X. Wang, M. Wang, et al. 2010;67(12):867-71. PubMed · Publisher · Free full text

Abstract

Objective: To confirm the association between exposure to chrysotile asbestos and lung cancer risk and to demonstrate the combined effect of smoking and asbestos exposure.

Methods: A case-control study of 1139 asbestos workers identified 41 male lung cancer cases in 2001; each case was matched by age (±5 years) with five controls. Workers in seven workshops were categorised into high-, medium- and low-exposure subgroups, and conditional logistic regression was applied to estimate the odds ratios for lung cancer risk associated with the different exposure levels. Smoking, age at first exposure, and exposure duration were considered as covariates/confounding factors. A joint effect of asbestos exposure and smoking on lung cancer risk was analysed using a conditional logistical model.

Results: 54% of cases had high exposure and 24% low exposure, while 24% of controls had high exposure and 44% low exposure. Smoking was more common in cases (90%) than in controls (73%). The adjusted OR for lung cancer was 3.66 (95% CI 1.61 to 8.29) for high exposure and was elevated slightly for medium exposure (1.25; 95% CI 0.47 to 3.31). Smoking was related to lung cancer risk (OR 3.33; 95% CI 1.10 to 10.08). In comparison with the low-exposure non-smoking group, the OR for the high-exposure smoking group was 10.39 (1.34 to 82.45), in contrast to 5.23 (0.50 to 54.58) for high-exposure non-smoking workers.

Conclusions: These results confirm the strong association between exposure to chrysotile asbestos and lung cancer risk, and support an interactive effect of asbestos exposure and smoking which is more than additive.
Mesothelioma risk from chrysotile. J.T. Hodgson, A. Darnton. 2010;67(6):432. Comment · Letter PubMed · Publisher

Summary

This letter responded to a 2009 analysis by Loomis et al of asbestos-related mortality in North Carolina textile plants exposed to chrysotile. The authors compared those results with their own earlier meta-analysis. The new lung cancer risk, a relative risk of 1.102 per 100 f/ml.yr, translated almost exactly to an excess of 0.1% per f/ml.yr, identical to their earlier best estimate. The new mesothelioma risk was 10 times higher than in the meta-analysis. In a chart of chrysotile cohorts, the Canadian mines gave a low, reasonably precise estimate of about 0.001. With the mines excluded, the remaining cohorts were statistically consistent (p=0.075), mainly because the estimates were imprecise. Their mean risk was 0.0070 (confidence limits 0.0038 to 0.013). The two mining cohorts combined gave 0.00096 (95% CI 0.00069 to 0.0013). The new estimate rested on eight cases, and up to three may have been due to amosite exposure in one plant. An estimate of 0.007% per f/ml.yr was still at least an order of magnitude below the amphibole estimates (0.5 for crocidolite, 0.1 for amosite). Mixed-fibre cohorts suggested a chrysotile risk well below 0.01 in friction products. The authors concluded that the new results strengthened the case that the per-fibre mesothelioma risk from chrysotile is greater in textile plants than in mines. They said it was unclear whether this difference applies in other settings.

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Non-occupational exposure to asbestos and malignant mesothelioma in the Italian National Registry of Mesotheliomas. D. Mirabelli, D. Cavone, E. Merler, et al. 2010;67(11):792-4. PubMed · Publisher

Abstract

Background: Malignant mesotheliomas are strictly related to asbestos, but in a proportion of cases no exposure can be recalled. Published estimates of this proportion have important variations. Historical and geographical differences in the fraction of cancer due to any given exposure are to be expected, but incomplete identification of non-occupational exposures may have played a role.

Methods: To assess the role of non-occupational exposures in causing malignant mesotheliomas in Italy, the exposures of cases registered by the national mesothelioma registry (ReNaM) were examined. ReNaM started in 1993 in five regions and currently covers 98% of the Italian population. Information on occupational and non-occupational exposures of cases is collected whenever possible.

Results: From 1993 to 2001 ReNaM registered 5173 malignant mesothelioma cases, and exposures were assessed in 3552 of them. 144 and 150 cases with exposures limited to environmental (living in the neighbourhood of an industrial or natural source of asbestos) or familial (living with a person occupationally exposed to asbestos) circumstances, respectively, were identified, accounting for 8.3% of all cases.

Conclusions: Geographical variations in the proportion of cases due to non-occupational exposures may be explained by the past distribution of asbestos-using industries.
Occupational exposure to asbestos in New South Wales, Australia (1970-1989): development of an asbestos task exposure matrix. R.A. Hyland, D.H. Yates, G. Benke, et al. 2010;67(3):201-6. PubMed · Publisher

Abstract

Objectives: To design and construct a standardised tool to provide exposure information associated with commonly used asbestos products and their related tasks in New South Wales (NSW), Australia.

Methods: Asbestos dust exposure measurements taken during workplace inspections in the 1970s and 1980s were collected and stored in an exposure database. Measurements were assigned to specific asbestos product and task groups and divided into two sampling periods 1970-1979 and 1980-1989.

Results: A total of 1578 asbestos air measurements collected from WorkCover and Dust Diseases Board company records were entered into a custom built exposure database. An asbestos-specific exposure matrix (ASTEM) was constructed in Microsoft Excel 2000, consisting of 3 axes incorporating 12 tasks, 8 asbestos products and the 2 time periods based on 872 individual measurements extracted from the exposure database. Each matrix cell contains the mean asbestos exposure levels measured in fibres/ml, 5th and 95th percentiles and number of data points in the set.

Conclusion: An ASTEM has been developed which provides exposure levels for different task/product combinations. When used in conjunction with a detailed occupational history, it will improve exposure estimates of a worker's cumulative asbestos exposure.
Occupational exposure to polycyclic aromatic hydrocarbons and lung cancer risk: a multicenter study in Europe. A.C. Olsson, J. Fevotte, T. Fletcher, et al. 2010;67(2):98-103. PubMed · Publisher

Abstract

Background: Lung cancer incidence in Central and Eastern Europe (CEE) is among the highest in the world, and the role of occupational exposures has not been adequately studied in these countries.

Objectives: To investigate the contribution of occupational exposure to polycyclic aromatic hydrocarbons (PAH) to lung cancer in CEE.

Methods: A case-control study was conducted in the Czech Republic, Hungary, Poland, Romania, Russia and Slovakia, as well as the United Kingdom (UK) between 1998 and 2002. Occupational and socio-demographic information was collected through interviews from 2861 newly diagnosed lung cancer cases and 2936 population or hospital controls. Industrial hygiene experts in each country evaluated exposure to 70 occupational agents, whereof 15 mixtures containing PAH. ORs of lung cancer were calculated after adjusting for other occupational exposures and tobacco smoking.

Results: The OR for ever exposure to PAH in the CEE countries was 0.93 (95% CI 0.77 to 1.14). The ORs for the highest category of cumulative exposure, duration of exposure and intensity of exposure were 1.13 (95% CI 0.80 to 1.58), 1.02 (95% CI 0.66 to 1.57) and 1.11 (95% CI 0.60 to 2.05), respectively. The OR for ever PAH exposure in the UK was 1.97 (95% CI 1.16 to 3.35).

Conclusion: Occupational PAH exposure does not appear to substantially contribute to the burden of lung cancer in CEE. The apparently stronger effect observed in the UK may be due to high exposure levels and a joint effect with asbestos.
Occupational exposure to silica and lung cancer risk in the Netherlands. L. Preller, L.M. van den Bosch, P.A. van den Brandt, et al. 2010;67(10):657-63. PubMed · Publisher

Abstract

Objectives: The lung cancer carcinogenicity of crystalline silica dust remains the subject of discussion. Epidemiological evidence is based on occupational cohort studies and population-based case-control studies. The aim of this study was to assess associations between male lung cancer risk and silica exposure in a population-based cohort study.

Methods: The study was conducted among men aged 55-69 years (n=58 279) from the Netherlands Cohort Study, which included self-reported, life-time job histories. Job titles were linked to the occupational groups of the external Finnish Job Exposure Matrix (FINJEM), including probability and level of silica exposure, each for specific time periods. 1667 incident lung cancer cases with known silica exposure status (210 exposed) were available after 11.3 years of follow-up. Risks were estimated based on a case-cohort design, and using Cox proportional hazards models.

Results: Adjusted for smoking and other confounders, elevated risks were observed for exposure duration (RR 1.65, 95% CI 1.14 to 2.41 for 26-51 years vs no exposure) and cumulative exposure (RR 1.47, 95% CI 0.93 to 2.33 for ≥3 vs <3 mg/m(3).year). Associations with average exposure levels were weaker. Associations were stronger for occupations with an exposure probability of ≥90%. Adjustment for asbestos exposure slightly increased the risk.

Conclusions: Results from this prospective population-based cohort study corroborate the classification of crystalline silica as a lung carcinogen. Associations could not be explained by smoking or by asbestos exposure.
Polymorphisms in the putative micro-RNA-binding sites of mesothelin gene are associated with serum levels of mesothelin-related protein. A. Cristaudo, R. Foddis, A. Bonotti, et al. 2010;67(4):233-6. PubMed · Publisher

Abstract

Background: Serum mesothelin, also known as soluble mesothelin-related protein (SMRP), reportedly shows increased levels in epithelial-type malignant pleural mesothelioma, but sometimes also arrives at high values in healthy asbestos-exposed subjects.

Objectives: This study aimed to investigate whether single nucleotide polymorphisms in the 3'untranslated region (3'UTR) of the mesothelin-encoded gene (MSLN) are associated with the SMRP levels measured in serum.

Methods: The 3'UTR of the mesothelin gene was genotyped in 59 healthy asbestos-exposed subjects, selected on the basis of their SMRP levels. Direct sequencing did not show any new polymorphism, but enabled us to genotype two known SNPs (rs1057147, rs57272256). Differences in the mean values of SMRP in wild-type and variant heterozygote groups were calculated.

Results: High levels of SMRP in healthy asbestos-exposed subjects were significantly associated with polymorphism rs1057147 (G<A). Regarding rs57272256, there was no statistically significant difference between wild-type and heterozygote groups. Our study suggests that rs1057147 polymorphism can affect mesothelin expression. Although these data need to be confirmed with a larger number of cases, this study warrants further research in order to better understand the relationship between mesothelin polymorphisms and SMRP.
Possible effect of environmental exposure to asbestos on geographical variation in mesothelioma rates. S. Goldberg, G. Rey, D. Luce, et al. 2010;67(6):417-21. PubMed · Publisher

Abstract

Background: In population-based mesothelioma studies in industrialised countries, the incidence of mesothelioma without any identified asbestos exposure (IAE) is usually higher among women, while male incidence is mainly attributed to IAE. Through a comparison of the spatial distribution of male and female rates, and IAE and no IAE incidence, this study investigated whether mesotheliomas without IAE are in fact induced by non-recognised asbestos exposure, mostly from environmental sources.

Methods: We calculated mesothelioma mortality (SMR) and incidence (SIR) ratios by district in France, pooling 30 and 10 years of data, respectively. Using correlation coefficients, we compared geographical patterns of male and female mesothelioma ratios, and IAE and no IAE mesothelioma ratios.

Results: The raw numbers of male and female mesothelioma cases were equivalent. Mesothelioma SMR (0.76) and SIR (0.80) geographical correlations between men and women were strongly positive. SIR correlation between occupationally IAE and no IAE cases was also positive (0.69). Correlation between occupationally IAE and no IAE cases was positive among women but not among men.

Conclusions: Data analyses of mesothelioma mortality and incidence showed that female cases occur in the same geographical areas as male cases. Female mesotheliomas with no IAE occur in the same geographical areas as exposed cases, suggesting asbestos has a major influence on female mesothelioma, likely through environmental exposure.
Programmed health surveillance and detection of emerging diseases in occupational health: contribution of the French national occupational disease surveillance and prevention network (RNV3P). V. Bonneterre, L. Faisandier, D. Bicout, et al. 2010;67(3):178-86. PubMed · Publisher

Abstract

Objective: The French national occupational disease surveillance and prevention network (RNV3P) includes the 30 occupational disease consultation centres in university hospitals to which patients are referred for potentially work-related diseases, and an occupational health service. The aim of this work is to demonstrate the contribution of RNV3P to national health surveillance.

Methods: Data from consultations are recorded in standardised occupational health reports and coded using international or national classifications. Programmed health surveillance is carried out through annual follow-up of annual referrals to experts for pre-selected disease-exposure associations, as well as incidence estimations for the well characterised working population followed by the occupational health service. Hypotheses on new emerging diseases are generated using statistical methods employed in pharmacosurveillance and by modelling as an exposome to analyse multiple exposures.

Results: 58,777 occupational health reports were collected and analysed from 2001 to 2007. Referrals to the 30 university hospital centres increased significantly for asbestos-related diseases, mood disorders and adjustment disorders related to psychological and organisational demands, and for elbow and shoulder disorders related to manual handling. Referrals significantly decreased for asthma and for rhinitis related to exposure to organic dusts (vegetable or animal) or chemicals, except for cosmetics and cleaning products. Estimation of incidences by the occupational health services showed different patterns in different sectors of activity. The methods for detecting emerging diseases are presented and illustrated using the example of systemic sclerosis, identifying new exposures and new sectors of activity to be investigated.

Conclusion: The RNV3P collects data from two complementary samples: 30 university hospital centres (workers or former workers) and an occupational health service (current workers). This dual approach is useful for surveillance and for hypothesis generation on new emerging disease-exposure associations.
The incidence of medically reported work-related ill health in the UK construction industry. S.J. Stocks, R. McNamee, M. Carder, et al. 2010;67(8):574-6. PubMed · Publisher

Abstract

Objective: Self-reported work-related ill health (SWI) data show a high incidence of occupational ill health and a high burden of cancer attributable to occupational factors in the UK construction industry. However, there is little information on the incidence of medically reported work-related ill health (WRI) within this industry. This study aims to examine the incidence of WRI within the UK construction industry.

Method: Standardised incidence rate ratios (SRRs) were used to compare incidence rates of reports of medically certified work-related ill health returned to The Health and Occupation Reporting network (THOR) within the UK construction industry with all other UK industries combined.

Results: Male UK construction industry workers aged under 65 years had significantly raised SRRs for respiratory (3.8, 95% CI 3.5 to 4.2), skin (1.6, 1.4 to 1.8) and musculoskeletal disorders (MSD; 1.9, 1.6 to 2.2). These SRRs were further raised for those working within a construction trade. The increased SRRs for skin disease within male construction industry workers were due to contact dermatitis (1.4, 1.2 to 1.6) and neoplasia (4.2, 3.3 to 5.3). For respiratory disease, the increased SRRs were due to non-malignant pleural disease (7.1, 6.3 to 8.1), mesothelioma (7.1, 6.0 to 8.3), lung cancer (5.4, 3.2 to 8.9) and pneumoconiosis (5.5, 3.7 to 8.0), but the SRRs for asthma (0.09, 0.06 to 0.11) and mental ill health (0.3, 0.1 to 0.4) were significantly reduced.

Conclusion: The significantly raised SRRs for medically reported MSD and significantly reduced SRRs for mental ill health in construction workers confirm self-reported UK data. These SRRs provide a baseline of the incidence of WRI in the UK construction industry from which to monitor the effects of changes in policy or exposures.
Work-related mortality in England and Wales, 1979-2000. D. Coggon, E.C. Harris, T. Brown, et al. 2010;67(12):816-22. PubMed · Publisher · Free full text

Abstract

Background: To explore time trends in deaths attributable to work in England and Wales, and identify priorities for prevention, we conducted a proportional analysis of mortality by occupation over a 22-year period.

Methods: Analysis was based on deaths in men aged 20-74 years during 1979-1980 and 1982-2000 with a recorded occupation. Proportional mortality ratios, standardised for age and social class, were calculated for pre-specified combinations of occupation and cause of death, for which excess mortality could reasonably be attributed to work. Differences between observed and expected numbers of deaths by cause and occupation were expressed as annual excess death rates.

Results: Mortality attributable to work declined substantially over the period of study, with total excess death rates of 733.2 per year during 1979-1990 and 471.7 per year during 1991-2000. The largest contributing hazards were chronic obstructive pulmonary disease and pneumoconiosis in coal miners, pleural cancer from asbestos, and motor vehicle accidents in lorry drivers. In contrast to most other hazards, there was no clear decline in excess mortality attributable to asbestos, or in deaths from sino-nasal cancer associated with exposure to wood dust.

Conclusions: The overall decline in mortality attributable to work is likely to reflect reduced employment in more hazardous occupations, as well as improvements in working conditions. It is imperative to ensure that occupational exposures to asbestos and wood dust are now adequately controlled. Further research is needed on accidents involving lorries with the aim of developing more effective strategies for the prevention of injury.

2000s

Asbestos, lung cancer and mesothelioma in the British Journal of Industrial Medicine. A. Newman Taylor. 2009;66(7):426-7. Editorial · Historical article PubMed · Publisher

Summary

In this editorial, the author reviewed three papers from the archives of the British Journal of Industrial Medicine, which he described as arguably the most influential papers in occupational lung disease of the 20th century. In Doll's 1955 study of male Turner Brothers Asbestos employees in Rochdale who had worked at least 20 years in dusty areas, 39 deaths from all causes were observed against 15.4 expected. These included 11 lung cancer deaths, all with asbestosis. The company's directors had pressed Doll and the journal's editor not to publish. Wagner, Sleggs and Marchand found that all but one of 33 cases of pleural mesothelioma had been exposed to crocidolite, mostly in the North Western Cape Province of South Africa, some only as children living near the mines. Newhouse and Thompson's 1965 case-control study of 83 mesothelioma deaths from London Hospital records found asbestos exposure in 40 (55%) cases and nine (12%) controls. Nine exposed cases had relatives who worked with asbestos, most commonly wives who washed work clothes. Among cases without occupational or domestic exposure, 11 (31%) lived within 0.5 miles of an asbestos factory, compared with five (8%) controls. The author concluded that these papers showed that asbestos causes lung cancer and mesothelioma, leading eventually to bans on asbestos imports in the UK and Europe. He noted that unrecognised residual asbestos, chiefly among construction workers, is the primary reason for the continuing rise in mesothelioma.

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Asbestosis mortality in the USA: facts and predictions. V.C. Antao, G.A. Pinheiro, J.T. Wassell. 2009;66(5):335-8. PubMed · Publisher

Abstract

Background: Mortality trends in the USA show that deaths from asbestosis are increasing, while deaths related to other pneumoconiosis are declining.

Objectives: To analyse the association between asbestos consumption and asbestosis mortality trends.

Methods: In an epidemiological time series study, we used a modern computer-intensive local regression method to evaluate the relationship between asbestos consumption per capita (1900-2006) as the predictor variable and number of deaths from asbestosis (1968-2004). The predictor variable was progressively lagged by annual increments from 30 to 60 years and the goodness of fit assessed for each lag period. The model having the smallest Akaike's Information Criteria was used to derive extrapolated estimates of future mortality based on more recent asbestos consumption data.

Results: Asbestos consumption per capita reached a peak in 1951 and gradually declined until 1973, when it started to drop rapidly. In 2006, it was 0.0075 kg/person/year. There were 25 564 deaths from asbestosis over the period 1968-2004. The best-fitting model (adjusted coefficient of determination (R(2)) = 99.7%) for 1968-2004 deaths from asbestosis used asbestos consumption per capita 48 years prior (1920-1956) and the log value of asbestos consumption per capita 43 years prior (1925-1961). This model predicts a total of 29 667 deaths (95% CI 19 629 to 39 705) to occur during 2005-2027 (an average of 1290 deaths per year).

Conclusions: This study demonstrates a clear association between asbestos consumption and deaths from asbestosis and indicates that asbestosis deaths are not expected to decrease sharply in the next 10-15 years.
Estimates of historical exposures by phase contrast and transmission electron microscopy in North Carolina USA asbestos textile plants. J.M. Dement, D. Myers, D. Loomis, et al. 2009;66(9):574-83. PubMed · Publisher

Abstract

Objectives: To develop a job-exposure matrix (JEM) for fibre exposures in three asbestos textile plants and to develop estimates of fibre size-specific exposures.

Methods: Historical dust samples from three North Carolina, USA asbestos textile plants were obtained. Plant specific samples were used to express impinger dust concentrations as fibre concentrations by phase contract microscopy (PCM). Mixed models were used to estimate PCM exposures by plant, department, job and calendar time. Archived membrane filter samples were analysed by transmission electron microscopy (TEM) to determine the bivariate diameter/length distribution of airborne fibres by plant and operation.

Results: PCM fibre levels estimated from the models were very high in the 1930s, with some operations having in excess of 200 fibres/ml, and decreased appreciably over time. TEM results for 77 airborne dust samples found that only a small proportion of airborne fibres were measured by PCM (>0.25 microm in diameter and >5 microm in length) and the proportion varied considerably by plant and operation (range 2.9% to 10.0%). The bivariate diameter/length distribution of airborne fibres demonstrated a relatively high degree of variability by plant and operation. PCM adjustment factors also varied substantially across plants and operations.

Conclusions: These data provide new information concerning airborne fibre levels and characteristics in three historically important asbestos textile plants. PCM concentrations were high in the early years and TEM data demonstrate that the vast majority of airborne fibres inhaled by the workers were shorter than 5 microm in length, and thus not included in the PCM-based fibre counts.
Lung cancer mortality and fibre exposures among North Carolina asbestos textile workers. D. Loomis, J.M. Dement, S.H. Wolf, et al. 2009;66(8):535-42. PubMed · Publisher

Abstract

Objective: To describe mortality among workers exposed to chrysotile asbestos and evaluate the relationship between lung cancer and asbestos fibre exposure.

Methods: Workers employed for at least 1 day between 1 January 1950 and 31 December 1973 in any of four plants in North Carolina, USA that produced asbestos textile products were enumerated. Vital status was ascertained through 31 December 2003. Historical exposures to asbestos fibres were estimated from work histories and 3578 industrial hygiene measurements taken in 1935-1986. Mortality of the cohort was compared with that of the national population via standardised mortality ratios (SMRs). Exposure-response relationships for lung cancer were examined within the cohort using Poisson regression to compute adjusted mortality rate ratios.

Results: Follow-up of 5770 workers included in the cohort resulted in 181 640 person-years of observation, with 2583 deaths from all causes and 277 from lung cancer. Mortality from all causes, all cancers and lung cancer was significant higher than expected, with SMRs of 1.47 for all causes, 1.41 for all cancer and 1.96 (95% CI 1.73 to 2.20) for lung cancer. SMRs for pleural cancer, mesothelioma and pneumoconiosis were also elevated. The risk of lung cancer and asbestosis increased with cumulative fibre exposure (RR 1.102 per 100 fibre-year/ml, 95% CI 1.044 to 1.164, and RR 1.249 per 100 fibre-year/ml, 95% CI 1.186 to 1.316, respectively, for total career exposure).

Conclusions: This study provides further evidence that exposure to chrysotile asbestos in textile manufacturing is associated with increased risk of lung cancer, asbestosis cancer of the pleura and mesothelioma.
Mortality among British asbestos workers undergoing regular medical examinations (1971-2005). A.H. Harding, A. Darnton, J. Wegerdt, et al. 2009;66(7):487-95. PubMed · Publisher

Abstract

Objectives: The Great Britain Asbestos Survey was established to monitor mortality among workers covered by regulations to control occupational exposure to asbestos. This study updates the estimated burden of asbestos-related mortality in the cohort, and identifies risk factors associated with mortality.

Methods: From 1971, workers were recruited during initially voluntary and later statutory medical examinations. A brief questionnaire was completed during the medical, and participants were flagged for death registrations. Standardised mortality ratios (SMRs) and proportional mortality ratios (PMRs) were calculated for deaths occurring before 2006. Poisson regression analyses were undertaken for diseases with significant excess mortality.

Results: There were 15 496 deaths among 98 117 workers followed-up for 1 779 580 person-years. The SMR for all cause mortality was 141 (95% CI 139 to 143) and for all malignant neoplasms 163 (95% CI 159 to 167). The SMRs for cancers of the stomach (166), lung (187), peritoneum (3730) and pleura (968), mesothelioma (513), cerebrovascular disease (164) and asbestosis (5594) were statistically significantly elevated, as were the corresponding PMRs. In age and sex adjusted analysis, birth cohort, age at first exposure, year of first exposure, duration of exposure, latency and job type were associated with the relative risk of lung, pleural and peritoneal cancers, asbestosis and mesothelioma mortality.

Conclusions: Known associations between asbestos exposure and mortality from lung, peritoneal and pleural cancers, mesothelioma and asbestosis were confirmed, and evidence of associations with stroke and stomach cancer mortality was observed. Limited evidence suggested that asbestos-related disease risk may be lower among those first exposed in more recent times.
Mortality among British asbestos workers. B. Sjögren. 2009;66(12):854-5. Letter · Comment PubMed · Publisher

Summary

In this letter, the author responded to a study by Harding and coworkers of 98 117 British asbestos workers followed for 1 779 580 person-years. That study found increased mortality from ischaemic heart disease (IHD), with an SMR of 1.40 (95% CI 1.36 to 1.44) and 4183 IHD deaths among 15 496 deaths in total. The author noted that factors such as length of exposure, latency, smoking status and main job category had been taken into account for several cancers, asbestosis and cerebrovascular disease, but IHD was not analysed further. He argued for closer study. He cited evidence that particulate air pollution is associated with cardiovascular hospital admissions and deaths, possibly with no threshold. He stated that whether inhaled asbestos fibres cause IHD is an unsolved question. He then summarised earlier studies. These reported increased circulatory or IHD mortality among US chrysotile textile workers (SMR 1.20, 95% CI 1.10 to 1.32), US asbestos company retirees, Italian chrysotile miners (SMR 1.48) and more heavily exposed Quebec miners and millers. Other studies linked pleural changes or plaques with heart disease. Swedish shipyard workers with asbestosis or suspected asbestosis had a higher risk of IHD death (RR 3.1, 95% CI 1.5 to 6.4). He cited raised inflammatory markers in patients with asbestosis. He proposed that inhaled particles cause low-grade inflammation and increased clotting agents, raising IHD risk. He encouraged the original authors to examine asbestos exposure and IHD in internal analyses.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.
Mortality from cancer and other causes in the Balangero cohort of chrysotile asbestos miners. E. Pira, C. Pelucchi, P.G. Piolatto, et al. 2009;66(12):805-9. PubMed · Publisher

Abstract

Objectives: To provide further information on mortality from cancer and other causes among chrysotile asbestos miners several years after exposure ceased, we updated the analyses from the Balangero mine worker cohort with follow-up to the end of 2003.

Methods: The cohort included 1056 men, for a total of 34 432 man-years of observation. We obtained employment data from factory personnel records, and ascertained vital status and causes of death through population registers and death certificates from municipal registration offices. We computed expected numbers of deaths and standardised mortality ratios (SMRs) for relevant causes using the province of Turin and national death rates, for each 5-year calendar period and age group.

Results: We found a significant excess mortality from pleural cancer only (4 deaths, SMR 4.67) and pleural and peritoneal cancers combined (5 deaths, SMR 3.16). All pleural and peritoneal cancer deaths occurred 30 or more years after first exposure. The SMRs were 1.27 for lung cancer (45 deaths), 1.82 for laryngeal cancer (8 deaths) and 1.12 for all cancers (142 deaths). Cumulative dust exposure and the various time factors considered did not show a clear pattern of risk associated with mortality from lung cancer. There were 57 deaths from cirrhosis (SMR 2.94) and 54 from accidents and violence (SMR 1.88). Overall, we observed a total of 590 deaths as compared to 412.9 expected (SMR 1.43).

Conclusions: This updated analysis, with almost 60% of the cohort having died, confirmed the excess mortality from pleural and peritoneal cancers and from several alcohol-related causes.
Performance of chest radiograph and CT scan for lung cancer screening in asbestos-exposed workers. B. Clin, F. Morlais, L. Guittet, et al. 2009;66(8):529-34. PubMed · Publisher

Abstract

Objectives: The aim was to compare, in a cohort of asbestos-exposed workers, the sensitivity and the specificity of low-radiation helical chest CT scan with chest radiograph for the biennial screening of bronchopulmonary cancer, according to the size of detected nodules.

Material And Methods: The screening procedure consisted of biennial chest radiograph and monodetector chest CT scan, given to 972 individuals who had been highly exposed to asbestos. A total of 2555 screening procedures were performed. The study focuses on the 1230 screening procedures for which a 2-year follow-up period was available.

Results: Twenty-four cases of bronchopulmonary cancer were diagnosed. CT scan detected 20 cancers, 12 of which had not been detected by chest radiograph. Sensitivity of chest radiograph and CT scan were, respectively, 33% and 83%, lesions measuring over 2 mm in diameter being considered as suspect. The specificity of chest radiograph and CT scan were, respectively, 95% and 78%. Calculation of the differential false positive/true positive (FP/TP) ratio and the receiver operating characteristic curve, performed for both chest radiograph and CT scan, facilitated the determination of the best possible compromise between specificity and sensitivity, according to the diameter threshold applied for considering a nodule as suspect.

Conclusions: Although this study confirms the superior sensitivity of chest CT scan compared with conventional chest radiograph, the associated loss in specificity leads to a recommended diameter of 5 mm as the threshold for considering non-calcified lesions as "suspect", for the surveillance of asbestos-exposed individuals.
Predicted mortality from malignant mesothelioma among women exposed to blue asbestos at Wittenoom, Western Australia. A. Reid, G. Berry, J. Heyworth, et al. 2009;66(3):169-74. PubMed · Publisher

Abstract

Introduction: Nearly 3000 women and girls were documented to have lived at the blue asbestos mining and milling town of Wittenoom in Western Australia between 1943 and 1992. Eight per cent of deaths among these women to the end of 2004 have been from malignant mesothelioma of the pleura.

Aim: To predict future mortality from mesothelioma to 2030 in this cohort.

Methods: Mesothelioma mortality rates incorporating parameters for cumulative exposure, a power of time since first exposure and annual rates of fibre clearance from the lung were calculated from maximum likelihood estimates. These rates plus age specific mortality rates for Western Australian females incorporating an excess lung cancer risk were then applied to all Wittenoom cohort women surviving to the end of 2004, in yearly increments, to predict the future numbers of cases of mesothelioma to 2030.

Results: There were 40 deaths from mesothelioma among the Wittenoom women to the end of 2004. Using a range of models that incorporate time since first exposure, competing risks from other diseases, latency periods and clearance of mesothelioma from the lungs we predict 66 (lowest estimate) to 87 (highest estimate) deaths from mesothelioma until 2030. This represents one and a half to two and a half times the number of deaths that have already occurred to the end of 2004.

Conclusion: The high toll from mesothelioma in this cohort of women and girls will continue well into the future.
The upholsterer and the asbestos. C. Mensi, A. Garberi, R. Trinco, et al. 2009;66(12):855. Case report · Letter PubMed · Publisher
An epidemiological study of the role of chrysotile asbestos fibre dimensions in determining respiratory disease risk in exposed workers. L. Stayner, E. Kuempel, S. Gilbert, et al. 2008;65(9):613-9. PubMed · Publisher

Abstract

Background: Evidence from toxicological studies indicates that the risk of respiratory diseases varies with asbestos fibre length and width. However, there is a total lack of epidemiological evidence concerning this question.

Methods: Data were obtained from a cohort mortality study of 3072 workers from an asbestos textile plant which was recently updated for vital status through 2001. A previously developed job exposure matrix based on phase contrast microscopy (PCM) was modified to provide fibre size-specific exposure estimates using data from a re-analysis of samples by transmission electron microscopy (TEM). Cox proportional hazards models were fit using alternative exposure metrics for single and multiple combinations of fibre length and diameter.

Results: TEM-based cumulative exposure estimates were found to provide stronger predictions of asbestosis and lung cancer mortality than PCM-based estimates. Cumulative exposures based on individual fibre size-specific categories were all found to be highly statistically significant predictors of lung cancer and asbestosis. Both lung cancer and asbestosis were most strongly associated with exposure to thin fibres (<0.25 microm). Longer (>10 microm) fibres were found to be the strongest predictors of lung cancer, but an inconsistent pattern with fibre length was observed for asbestosis. Cumulative exposures were highly correlated across all fibre size categories in this cohort (0.28-0.99, p values <0.001), which complicates the interpretation of the study findings.

Conclusions: Asbestos fibre dimension appears to be an important determinant of respiratory disease risk. Current PCM-based methods may underestimate asbestos exposures to the thinnest fibres, which were the strongest predictor of lung cancer or asbestosis mortality in this study. Additional studies are needed of other asbestos cohorts to further elucidate the role of fibre dimension and type.
Cancer risk after cessation of asbestos exposure: a cohort study of Italian asbestos cement workers. C. Magnani, D. Ferrante, F. Barone-Adesi, et al. 2008;65(3):164-70. PubMed · Publisher

Abstract

Objectives: We aimed to study mortality for asbestos related diseases and the incidence of mesothelioma in a cohort of Italian asbestos cement workers after cessation of asbestos exposure.

Methods: The Eternit factory operated from 1907 to 1986. The cohort included 3434 subjects active in 1950 or hired in 1950-86, ascertained from company records, without selections. Local reference rates were used for both mortality and mesothelioma incidence.

Results: Mortality was increased in both sexes for all causes (overall 1809 observed (obs) vs 1312.3 expected (exp); p<0.01), pleural (135 obs vs 3.6 exp; p<0.01) and peritoneal (52 vs 1.9; p<0.01) malignancies and lung cancer (249 vs 103.1; p<0.01). In women, ovarian (9 vs 4.0; p<0.05) and uterine (15 vs 5.8; p<0.01) malignancies were also in excess. No statistically significant increase was found for laryngeal cancer (16 obs vs 12.2 exp). In Poisson regression analyses, the RR of death from pleural neoplasm linearly increased with duration of exposure, while it showed a curvilinear increase with latency and time since cessation of exposure. RR for peritoneal neoplasm continued to increase by latency, duration and time since cessation of exposure. RR for lung cancer showed a reduction after 15 years since cessation of exposure and levelled off after 40 years of latency.

Conclusion: This study of a cohort of asbestos exposed workers with very long follow-up confirmed the reduction in risk of death from lung cancer after the end of exposure. It also suggested a reduction in risk for pleural mesothelioma with over 40 years of latency, while risk for peritoneal mesothelioma showed a continuing increase.
Development of a fibre size-specific job-exposure matrix for airborne asbestos fibres. J.M. Dement, E.D. Kuempel, R.D. Zumwalde, et al. 2008;65(9):605-12. PubMed · Publisher

Abstract

Objective: To develop a method for estimating fibre size-specific exposures to airborne asbestos dust for use in epidemiological investigations of exposure-response relations.

Methods: Archived membrane filter samples collected at a Charleston, South Carolina asbestos textile plant during 1964-8 were analysed by transmission electron microscopy (TEM) to determine the bivariate diameter/length distribution of airborne fibres by plant operation. The protocol used for these analyses was based on the direct transfer method published by the International Standards Organization (ISO), modified to enhance fibre size determinations, especially for long fibres. Procedures to adjust standard phase contrast microscopy (PCM) fibre concentration measures using the TEM data in a job-exposure matrix (JEM) were developed in order to estimate fibre size-specific exposures.

Results: A total of 84 airborne dust samples were used to measure diameter and length for over 18,000 fibres or fibre bundles. Consistent with previous studies, a small proportion of airborne fibres were longer than >5 microm in length, but the proportion varied considerably by plant operation (range 6.9% to 20.8%). The bivariate diameter/length distribution of airborne fibres was expressed as the proportion of fibres in 20 size-specific cells and this distribution demonstrated a relatively high degree of variability by plant operation. PCM adjustment factors also varied substantially across plant operations.

Conclusions: These data provide new information concerning the airborne fibre characteristics for a previously studied textile facility. The TEM data demonstrate that the vast majority of airborne fibres inhaled by the workers were shorter than 5 mum in length, and thus not included in the PCM-based fibre counts. The TEM data were used to develop a new fibre size-specific JEM for use in an updated cohort mortality study to investigate the role of fibre dimension in the development of asbestos-related lung diseases.
Excess of mesotheliomas after exposure to chrysotile in Balangero, Italy. D. Mirabelli, R. Calisti, F. Barone-Adesi, et al. 2008;65(12):815-9. PubMed · Publisher

Abstract

Background: Chrysotile from the mine in Balangero, Italy is considered to be free of tremolite. In a cohort study of miners and millers only two pleural cancers were reported, a finding considered to indicate that chrysotile has a low potency for inducing mesothelioma. However, follow-up ended in 1987 and white-collar workers and the employees of subcontractors were not studied.

Methods: To complete the case ascertainment, the study searched the Registry of Malignant Mesotheliomas of Piedmont for records of cases of pleural mesothelioma among the following: mine employees; employees of subcontractors or of other firms transporting or refining Balangero asbestos, asbestos ore or mine tailings; individuals exposed to air pollution from the mine or living with mine employees; and individuals exposed to mine tailings from Balangero.

Results: The study identified four new cases of pleural mesothelioma among blue-collar workers in the mine, in addition to the two reported in the cohort study. Thus, six mesotheliomas occurred, compared to the 1.5 expected (p<0.01). The study also identified three mesothelioma cases among white-collar employees at the mine, five in workers in the mine hired by subcontracting firms, and three among workers processing Balangero chrysotile outside the mine. Finally, 10 additional cases due to non-occupational exposure or exposure to re-used mine tailings were identified.

Conclusions: The cluster of 14 mesothelioma cases among workers who were active in the mine and 13 among other people exposed to Balangero chrysotile provides further evidence that tremolite-free chrysotile is carcinogenic.
Inequities in reporting asbestos-related lung cancer: influence of smoking stigma and physician's specialty, workload and role perception. P. Verger, S. Arnaud, S. Ferrer, et al. 2008;65(6):392-7. PubMed · Publisher

Abstract

Objectives: To study physician barriers to workers' compensation claims for asbestos-related cancers, focusing on smokers' stigma and physicians' speciality and role perception.

Methods: Cross-sectional telephone study of 486 randomly-selected general practitioners (GPs) and pulmonologists in south-eastern France. Standardised questionnaires explored their behaviour, attitudes and practices in the field of occupational health and their responses to a case vignette of a lung cancer patient with long-term occupational asbestos exposure. Randomised subgroups of GPs and pulmonologists heard alternative versions varying only as regards the worker's smoking status. We studied factors associated with the recommendation that the case vignette patient file a compensation claim with simple and multiple logistic regressions.

Results: The response rate was 64.4% among GPs and 62.5% among pulmonologists. Recommending the filing of an occupational disease claim was significantly associated in multiple logistic regressions with speciality (OR 4.46; 95% CI 2.38 to 8.37, for pulmonologists vs GPs), patient's smoking status (OR 3.15; 95% CI 2.11 to 4.70, for non-smokers vs smokers), physician's workload (OR 1.83; 95% CI 1.17 to 2.88, for </=25 consultations per day vs >25) and role perception (OR 2.00; 95% CI 1.22 to 3.27, for those who considered completing occupational disease medical certificates to be part of their role vs those who did not).

Conclusions: The results of this French study appear applicable to various countries and contexts. To make physicians and especially GPs more aware of occupational health and smoking stigma, officials and educators must give these topics higher priority during initial training and continuing medical education. Tools and equipment that take time constraints into account should be developed and disseminated to help physicians manage occupational diseases.
Mortality and cancer incidence of Australian participants in the British nuclear tests in Australia. R.T. Gun, J. Parsons, P. Crouch, et al. 2008;65(12):843-8. PubMed · Publisher

Abstract

Objectives: To investigate the mortality and cancer incidence of Australian nuclear test participants, and to identify any association with exposure to ionising radiation.

Methods: A retrospective cohort study was carried out in which the mortality and cancer incidence rates of participants (n = 10,983) were compared with rates in the general male Australian population. Dose reconstructions were carried out by a panel of health physicists. Mortality and cancer rates were compared with the general population and between groups of subjects categorised by assessed radiation exposure.

Results: All-cause mortality was not raised. Mortality and incidence were significantly raised for cancers of the head and neck, lung, colon and rectum, and prostate, and for all cancers combined. For oesophageal cancer, melanoma, all leukaemias and non-chronic lymphatic leukaemia (non-CLL leukaemia), incidence was significantly raised, but mortality was non-significantly raised. No association was found between radiation exposure and overall cancer incidence or mortality, or with any cancer or cancer deaths occurring in excess.

Conclusions: There is no evidence that the excess cancers and cancer deaths were caused by radiation exposure at the test sites. Possible contributing factors are high smoking prevalence and demographic differences from the Australian population with whom rates were compared. Asbestos is a likely contributor to some cancers in naval personnel.
Mortality of former crocidolite (blue asbestos) miners and millers at Wittenoom. A.W. Musk, N.H. de Klerk, A. Reid, et al. 2008;65(8):541-3. PubMed · Publisher

Abstract

Background: Blue asbestos was mined and milled at Wittenoom in Western Australia between 1943 and 1966.

Methods: Nearly 7000 male workers who worked at the Wittenoom mine and mill have been followed up using death and cancer registries throughout Australia and Italy to the end of 2000. Person-years at risk were derived using two censoring dates in order to produce minimum and maximum estimates of asbestos effect. Standardised mortality ratios (SMRs) compare the mortality of the former Wittenoom workers with the Western Australian male population.

Results: There have been 190 cases of pleural and 32 cases of peritoneal mesothelioma in this cohort of former workers at Wittenoom. Mortality from lung cancer (SMR = 1.52), pneumoconiosis (SMR = 15.5), respiratory diseases (SMR = 1.58), tuberculosis (SMR = 3.06), digestive diseases (SMR = 1.47), alcoholism (SMR = 2.24) and symptoms, signs and ill defined conditions (SMR = 2.00) were greater in this cohort compared to the Western Australian male population.

Conclusion: Asbestos related diseases, particularly malignant mesothelioma, lung cancer and pneumoconiosis, continue to be the main causes of excess mortality in the former blue asbestos miners and millers of Wittenoom.
Occupational exposures and risk of oesophageal cancer by histological type: a case-control study in eastern Spain. M. Santibañez, J. Vioque, J. Alguacil, et al. 2008;65(11):774-81. PubMed · Publisher

Abstract

Objective: To explore the relationship between occupations and specific occupational exposures and oesophageal cancer (OC) by histological type.

Methods: A multicentre hospital-based case-control study was conducted in two Mediterranean provinces of Spain. Occupational, sociodemographic and lifestyle information was collected from 185 newly diagnosed male oesophageal cancer patients (147 squamous cell, 38 adenocarcinoma) and 285 frequency matched controls. Occupation was coded according to the Spanish National Classification of Occupations 1994. Occupational exposure to a selection of carcinogenic substances was assessed by the FINJEM job exposure matrix. Odds ratios were calculated by unconditional logistic regression adjusting for age, education, alcohol intake and cigarette smoking.

Results: For the squamous cell variety, statistically significant associations were found for waiters and bartenders (OR 8.18, 95% CI 1.98 to 33.75) and miners, shotfirers, stone cutters and carvers (OR 10.78, 95% CI 1.24 to 93.7) in relation to other occupations. For the adenocarcinoma variety, statistically significant associations were observed for carpenters and joiners (OR 9.69), animal producers and related workers (OR 5.61) and building and related electricians (OR 8.26), although these observations were based on a low number of cases. Regarding specific exposures, the study found a statistically significant increased risk of squamous cell carcinoma for ionising radiation, and of adenocarcinoma for high exposure to volatile sulphur compounds (OR 3.12) and lead (OR 5.30). For all histological types of OC combined, a three-fold increase in risk was found with a significant trend for asbestos exposure (OR 3.46, 95% CI 0.99 to 12.10).

Conclusions: The data suggest that some occupational exposures may specifically increase the risk of oesophageal squamous cell carcinoma or adenocarcinoma, while other exposures such as asbestos may increase the overall risk of OC.
Professional exposure to carcinogenic substances: is occupational physicians' activity compatible with medical ethics and deontology?. B. Clin, M. Letourneux, G. Launoy. 2008;65(9):577-8. Editorial PubMed · Publisher
The burden of cancer at work: estimation as the first step to prevention. L. Rushton, S. Hutchings, T. Brown. 2008;65(12):789-800. PubMed · Publisher

Abstract

Objectives: Work-related cancers are largely preventable. The overall aim of this project is to estimate the current burden of cancer in Great Britain attributable to occupational factors, and identify carcinogenic agents, industries and occupations for targeting risk prevention.

Methods: Attributable fractions and numbers were estimated for mortality and incidence for bladder, lung, non-melanoma skin, and sinonasal cancers, leukaemia and mesothelioma for agents and occupations classified as International Agency for Research on Cancer (IARC) Group 1 and 2A carcinogens with "strong" or "suggestive" evidence for carcinogenicity at the specific cancer site in humans. Risk estimates were obtained from published literature and national data sources used for estimating proportions exposed.

Results: In 2004, 78,237 men and 71,666 women died from cancer in Great Britain. Of these, 7317 (4.9%) deaths (men: 6259 (8%); women: 1058 (1.5%)) were estimated to be attributable to work-related carcinogens for the six cancers assessed. Incidence estimates were 13,338 (4.0%) registrations (men: 11,284 (6.7%); women 2054 (1.2%)). Asbestos contributed over half the occupational attributable deaths, followed by silica, diesel engine exhaust, radon, work as a painter, mineral oils in metal workers and in the printing industry, environmental tobacco smoke (non-smokers), work as a welder and dioxins. Occupational exposure to solar radiation, mineral oils and coal tars/pitches contributed 2557, 1867 and 550 skin cancer registrations, respectively. Industries/occupations with large numbers of deaths and/or registrations include construction, metal working, personal and household services, mining (not metals), land transport and services allied to transport, roofing, road repair/construction, printing, farming, the Armed Forces, some other service industry sectors and manufacture of transport equipment, fabricated metal products, machinery, non-ferrous metals and metal products, and chemicals.

Conclusions: Estimates for all but leukaemia are greater than those currently used in UK health and safety strategy planning and contrast with small numbers (200-240 annually) from occupational accidents. Sources of uncertainty in the estimates arise principally from approximate data and methodological issues. On balance, the estimates are likely to be a conservative estimate of the true risk. Long latency means that past high exposures will continue to give substantial numbers in the near future. Although levels of many exposures have reduced, recent measurements of others, such as wood dust and respirable quartz, show continuing high levels.
The mortality of women exposed environmentally and domestically to blue asbestos at Wittenoom, Western Australia. A. Reid, J. Heyworth, N. de Klerk, et al. 2008;65(11):743-9. PubMed · Publisher

Abstract

Objectives: Knowledge of mortality patterns following exposure to asbestos has been determined mostly from cohort studies of men who were exposed to asbestos in their workplace. Women are more likely to have obtained their asbestos exposure domestically or from their environment.

Methods: 2552 women and girls are documented to have lived in the blue asbestos mining and milling township of Wittenoom between 1943 and 1992 and were not involved in asbestos mining or milling. Quantitative asbestos exposure measurements were derived from periodic dust surveys undertaken in the industry and around the township. Death records were obtained for the period 1950-2004. Standardised mortality ratios (SMRs) were calculated to compare the Wittenoom women's mortality with that of the Western Australian female population.

Results: There were 425 deaths, including 30 from malignant mesothelioma. There was excess mortality for all causes of death (SMR = 1.13), all neoplasms (SMR = 1.42), symptoms, signs and ill defined conditions (SMR = 6.35), lung cancer (SMR = 2.15) and pneumoconiosis (SMR = 11.8). Mortality from cancer of the ovary (SMR = 1.52), upper aerodigestive cancers (SMR = 2.70) and tuberculosis (SMR = 5.38) was increased but not significantly. The risk of death from mesothelioma was increased, but not significantly, in residents known to have lived with or washed the clothes of an Australian Blue Asbestos Company asbestos worker (HR = 2.67, 95% CI 0.77 to 9.21; HR = 2.61, 95% CI 0.85 to 7.99, respectively).

Conclusion: Women who were former residents of Wittenoom, exposed to asbestos in their environment or in their home, have excess cancer mortality, including mesothelioma, compared with the Western Australian female population.
Asbestos exposure and differences in occurrence of peritoneal mesothelioma between men and women across countries. A. Burdorf, B. Järvholm, S. Siesling. 2007;64(12):839-42. PubMed · Publisher · Free full text

Abstract

Objective: In several countries the incidence of peritoneal mesotheliomas among women closely mirrors the pattern among men. The aim was to investigate the role of asbestos exposure in the aetiology of peritoneal mesotheliomas in women and men.

Methods: All cases of peritoneal mesothelioma were selected from the Swedish and Netherlands Cancer Registers for the period 1989-2003. For both countries incidence rates were calculated and stratified by sex. A linear regression analysis was used to analyse the existence of a trend over time.

Results: Among men the incidence rate of peritoneal mesothelioma in the Netherlands (0.60 per 100 000 persons) was consistently higher than in Sweden with an average ratio of 1.8 (range 1.4-2.8). In both countries no trend over time was observed. During the 15-year period in the Netherlands the incidence rate among men was about 3.3-fold higher than among women. In Sweden the incidence rate among women was slightly higher than in men up to 1999, and thereafter about threefold higher among men. This sudden shift was statistically significant and seemed mainly caused by changes in classification of peritoneal tumours.

Conclusion: The absence of a time trend in the incidence rate of peritoneal mesothelioma in the Netherlands and Sweden in the past 15 years may point to a more limited role of occupational exposure to asbestos in the aetiology of peritoneal mesothelioma than for pleural mesothelioma, especially among women. The observed drop around 2000 in annual incidence of peritoneal mesothelioma among Swedish women indicates the presence in the past of a substantial misclassification with other tumours in the peritoneum.
Exposure to carcinogens for defined job categories in Norway's offshore petroleum industry, 1970 to 2005. K. Steinsvåg, M. Bråtveit, B.E. Moen. 2007;64(4):250-8. PubMed · Publisher · Free full text

Abstract

Objectives: To identify and describe the exposure to selected known and suspected carcinogenic agents, mixtures and exposure circumstances for defined job categories in Norway's offshore petroleum industry from 1970 to 2005, in order to provide exposure information for a planned cohort study on cancer.

Methods: Background information on possible exposure was obtained through company visits, including interviewing key personnel (n = 83) and collecting monitoring reports (n = 118) and other relevant documents (n = 329). On the basis of a previous questionnaire administered to present and former offshore employees in 1998, 27 job categories were defined.

Results: This study indicated possible exposure to 18 known and suspected carcinogenic agents, mixtures or exposure circumstances. Monitoring reports were obtained on seven agents (benzene, mineral oil mist and vapour, respirable and total dust, asbestos fibres, refractory ceramic fibres, formaldehyde and tetrachloroethylene). The mean exposure level of 367 personal samples of benzene was 0.037 ppm (range: less than the limit of detection to 2.6 ppm). Asbestos fibres were detected (0.03 fibres/cm3) when asbestos-containing brake bands were used in drilling draw work in 1988. Personal samples of formaldehyde in the process area ranged from 0.06 to 0.29 mg/m3. Descriptions of products containing known and suspected carcinogens, exposure sources and processes were extracted from the collected documentation and the interviews of key personnel.

Conclusions: This study described exposure to 18 known and suspected carcinogenic agents, mixtures and exposure circumstances for 27 job categories in Norway's offshore petroleum industry. For a planned cohort study on cancer, quantitative estimates of exposure to benzene, and mineral oil mist and vapour might be developed. For the other agents, information in the present study can be used for further assessment of exposure, for instance, by expert judgement. More systematic exposure surveillance is needed in this industry. For future studies, new monitoring programmes need to be implemented.
Follow-up study of chrysotile textile workers: cohort mortality and exposure-response. M.J. Hein, L.T. Stayner, E. Lehman, et al. 2007;64(9):616-25. PubMed · Publisher · Free full text

Abstract

Objectives: This report provides an update of the mortality experience of a cohort of South Carolina asbestos textile workers.

Methods: A cohort of 3072 workers exposed to chrysotile in a South Carolina asbestos textile plant (1916-77) was followed up for mortality through 2001. Standardised mortality ratios (SMRs) were computed using US and South Carolina mortality rates. A job exposure matrix provided calendar time dependent estimates of chrysotile exposure concentrations. Poisson regression models were fitted for lung cancer and asbestosis. Covariates considered included sex, race, age, calendar time, birth cohort and time since first exposure. Cumulative exposure lags of 5 and 10 years were considered by disregarding exposure in the most recent 5 and 10 years, respectively.

Results: A majority of the cohort was deceased (64%) and 702 of the 1961 deaths occurred since the previous update. Mortality was elevated based on US referent rates for a priori causes of interest including all causes combined (SMR 1.33, 95% CI 1.28 to 1.39); all cancers (SMR 1.27, 95% CI 1.16 to 1.39); oesophageal cancer (SMR 1.87, 95% CI 1.09 to 2.99); lung cancer (SMR 1.95, 95% CI 1.68 to 2.24); ischaemic heart disease (SMR 1.20, 95% CI 1.10 to 1.32); and pneumoconiosis and other respiratory diseases (SMR 4.81, 95% CI 3.84 to 5.94). Mortality remained elevated for these causes when South Carolina referent rates were used. Three cases of mesothelioma were observed among cohort members. Exposure-response modelling for lung cancer, using a linear relative risk model, produced a slope coefficient of 0.0198 (fibre-years/ml) (standard error 0.00496), when cumulative exposure was lagged 10 years. Poisson regression modelling confirmed significant positive relations between estimated chrysotile exposure and lung cancer and asbestosis mortality observed in previous updates of this cohort.

Conclusions: This study confirms the findings from previous investigations of excess mortality from lung cancer and asbestosis and a strong exposure-response relation between estimated exposure to chrysotile and mortality from lung cancer and asbestosis.
Investigating cancer risks related to asbestos and other occupational carcinogens. J. Siemiatycki. 2007;64(8):500-1. Editorial PubMed · Publisher · Free full text

Abstract

There will be little progress without investment in exposure assessment
Modelling mesothelioma risk for workers assembling military gas masks. J.W. Cherrie, H.A. Cowie, A.D. Jones. 2007;64(11):785-6; author reply 785-6. Comment · Letter PubMed · Free full text
Mortality among shipyard Coast Guard workers: a retrospective cohort study. S. Krstev, P. Stewart, J. Rusiecki, et al. 2007;64(10):651-8. PubMed · Publisher · Free full text

Abstract

Background: The mortality experience of 4702 (4413 men and 289 women) civilian workers in a US Coast Guard shipyard was evaluated.

Methods: All workers employed at the shipyard between 1 January 1950 and 31 December 1964 were included in the study and were followed through 31 December 2001 for vital status. Detailed shipyard and lifetime work histories found in the shipyard personnel records and job descriptions were evaluated. Workers were classified as likely exposed to any potential hazardous substances. In addition, 20 job groups were created on likely similar exposures. Standardised mortality ratios (SMRs) were calculated based on the general population of the state and adjusted for age, calendar period, sex and race.

Results: The follow-up was successful for 93.3% of the workers. Among all men employed in the shipyard, there was an excess of mortality from all causes of death (SMR 1.08; 95% CI 1.04 to 1.12), respiratory cancers (SMR 1.29; 95% CI 1.15 to 1.43), lung cancer (SMR 1.26; 95% CI 1.12 to 1.41), mesothelioma (SMR 5.07; 95% CI 1.85 to 11.03) and emphysema (SMR 1.44; 95% CI 1.01 to 1.99) and a decrease for cardiovascular diseases (OR 0.95; 95% CI 0.90 to 1.00), vascular lesions of the central nervous system (SMR 0.80; 95% CI 0.67 to 0.96), cirrhosis of the liver (SMR 0.38; 95% CI 0.25 to 0.57) and external causes of death (SMR 0.55; 95% CI 0.44 to 0.68). A similar pattern was observed for the men classified as exposed. No increasing trend of mortality was found with duration of employment in the shipyard, with the exception of mesothelioma (SMRs of 4.23 and 6.27 for <10 years and > or =10 years, respectively). In occupations with at least three cases and with an SMR of > or =1.3, the authors observed a significantly elevated mortality for lung cancer among machinists (SMR 1.60; 95% CI 1.08 to 2.29) and shipfitters, welders and cutters (SMR 1.34; 95% CI 1.07 to 1.65) and for oral and nasopharyngeal cancers among wood workers (SMR 6.20; 95% CI 2.27 to 13.50).

Conclusion: Employment in this Coast Guard shipyard revealed a small but significant excess mortality from all causes, lung cancer and mesothelioma, most of which is probably related to asbestos exposure.
Occupational exposure to asbestos and man-made vitreous fibres and risk of lung cancer: a multicentre case-control study in Europe. R. Carel, A.C. Olsson, D. Zaridze, et al. 2007;64(8):502-8. PubMed · Publisher · Free full text

Abstract

Objectives: To investigate the contribution of occupational exposure to asbestos and man-made vitreous fibres (MMVF) to lung cancer in high-risk populations in Europe.

Methods: A multicentre case-control study was conducted in six Central and Eastern European countries and the UK, during the period 1998-2002. Comprehensive occupational and sociodemographic information was collected from 2205 newly diagnosed male lung cancer cases and 2305 frequency matched controls. Odds ratios (OR) of lung cancer were calculated after adjusting for other relevant occupational exposures and tobacco smoking.

Results: The OR for asbestos exposure was 0.92 (95% CI 0.73 to 1.15) in Central and Eastern Europe and 1.85 (95% CI 1.07 to 3.21) in the UK. Similar ORs were found for exposure to amphibole asbestos. The OR for MMVF exposure was 1.23 (95% CI 0.88 to 1.71) with no evidence of heterogeneity by country. No synergistic effect either between asbestos and MMVF or between any of them and smoking was found.

Conclusion: In this large community-based study occupational exposure to asbestos and MMVF does not appear to contribute to the lung cancer burden in men in Central and Eastern Europe. In contrast, in the UK the authors found an increased risk of lung cancer following exposure to asbestos. Differences in fibre type and circumstances of exposure may explain these results.
Occupational exposure to particulate air pollution and mortality due to ischaemic heart disease and cerebrovascular disease. K. Torén, I.A. Bergdahl, T. Nilsson, et al. 2007;64(8):515-9. PubMed · Publisher · Free full text

Abstract

Objectives: A growing number of epidemiological studies are showing that ambient exposure to particulate matter air pollution is a risk factor for cardiovascular disease; however, whether occupational exposure increases this risk is not clear. The aim of the present study was to examine whether occupational exposure to particulate air pollution increases the risk for ischaemic heart disease and cerebrovascular disease.

Methods: The study population was a cohort of 176,309 occupationally exposed Swedish male construction workers and 71,778 unexposed male construction workers. The definition of exposure to inorganic dust (asbestos, man-made mineral fibres, dust from cement, concrete and quartz), wood dust, fumes (metal fumes, asphalt fumes and diesel exhaust) and gases and irritants (organic solvents and reactive chemicals) was based on a job-exposure matrix with focus on exposure in the mid-1970s. The cohort was followed from 1971 to 2002 with regard to mortality to ischaemic heart disease and cerebrovascular disease. Relative risks (RR) were obtained by the person-years method and from Poisson regression models adjusting for baseline values of blood pressure, body mass index, age and smoking habits.

Results: Any occupational particulate air pollution was associated with an increased risk for ischemic heart disease (RR 1.13, 95% CI 1.07 to 1.19), but there was no increased risk for cerebrovascular disease (RR 0.97, 95% CI 0.88 to 1.07). There was an increased risk for ischaemic heart disease and exposure to inorganic dust (RR 1.07, 95% CI 1.03 to 1.12) and exposure to fumes (RR 1.05, 95% CI 1.00 to 1.10), especially diesel exhaust (RR 1.18, 95% CI 1.13 to 1.24). There was no significantly increased risk for cerebrovascular disease and exposure to inorganic dust, fumes or wood dust.

Conclusions: Occupational exposure to particulate air pollution, especially diesel exhaust, among construction workers increases the risk for ischaemic heart disease.
Projected mesothelioma incidence in men in New South Wales. M. Clements, G. Berry, J. Shi, et al. 2007;64(11):747-52. PubMed · Publisher · Free full text

Abstract

Objectives: Based on observed numbers of incident mesotheliomas since 1972, to predict future numbers in men in New South Wales.

Methods: The incidence of mesothelioma was modelled in two ways. First by using an age/birth cohort model, and second by using a model based on potential exposure to asbestos in terms of age and calendar year. The latter model included a term for clearance of asbestos fibres from the lungs, and a term for diagnostic fraction. The age and calendar year model was based on the model introduced by Hodgson and colleagues but replaced piecewise effects by smooth functions represented by cubic splines.

Results: The number of mesotheliomas between 2004 and 2060 was predicted as 6690 with the age-cohort model and as 6779 by the age and calendar year model, with peak annual numbers of 187 in the year 2021 and 196 in the year 2014 with the two models respectively.

Conclusions: The pattern of parameter estimates in the two models was in accord with the known use of amphibole asbestos in Australia. The predicted peak year of 2014-21 is 30-35 years after the phasing out of amphibole use, and this period is in accord with predictions for the UK and the US; in the latter country the peak was 10-15 years earlier corresponding to a marked decline of amphibole use in and following the 1960s.
Shipyard workers and asbestos: a persistent and international problem. W.S. Beckett. 2007;64(10):639-41. Comment · Editorial PubMed · Publisher · Free full text

Abstract

Recycling ships for scrap also recycles the asbestos hazard
Asbestos, smoking, and lung cancer: interaction and attribution. B.W. Case. 2006;63(8):507-8. Comment PubMed · Publisher · Free full text

Abstract

Commentary on the paper by Reid et al (see page 509)
Exposure to non-arsenic pesticides is associated with lymphoma among farmers in Spain. E. van Balen, R. Font, N. Cavallé, et al. 2006;63(10):663-8. PubMed · Publisher · Free full text

Abstract

Objectives: To estimate the risk of lymphoma among farmers in Spain.

Methods: This is a multicentre case control study conducted in Spain. Cases were subjects diagnosed with lymphoma according to the World Health Organization (WHO) classification in four hospitals between 1998-2002. Hospital controls were frequency matched to the cases by sex, age, and centre. All subjects were interviewed about jobs ever held in lifetime for at least one year and the exposures in those jobs were recorded. The risk of lymphomas among subjects ever having had a job as a farmer was compared with all other occupations. Farmers were analysed according to the type of farming job performed: crop farming, animal farming, and general farming. Occupational exposure was summarised into 15 main categories: organic dust, radiation, contact with animals, PAH, non-arsenic pesticides (carbamates, organophosphates, chlorinated hydrocarbons, triazines and triazoles, phenoxy herbicides, chlorophenols, dibenzodioxin, and dibenzofuran), arsenic pesticides, contact with meat, contact with children, solvents, asbestos, soldering fumes, organic colourants, polychlorinated biphenyls, ethylene oxide, and hair dyes.

Results: Although farmers were not at an increased risk of lymphoma as compared with all other occupations, farmers exposed to non-arsenic pesticides were found to be at increased risk of lymphoma (OR = 1.8, 95% CI 1.1 to 2). This increased risk was observed among farmers working exclusively either as crop farmers or as animal farmers (OR = 2.8, 95% CI 1.3 to 5.8). Risk was highest for exposure to non-arsenic pesticides for over nine years (OR = 2.4, 95% CI 1.2 to 2.8).

Conclusions: Long term exposure to non-arsenic pesticides may induce lymphomagenesis among farmers.
Lung cancer risk and talc not containing asbestiform fibres: a review of the epidemiological evidence. P. Wild. 2006;63(1):4-9. Review PubMed · Publisher · Free full text

Abstract

A literature search was done and all epidemiological cancer studies mentioning talc as a risk factor were selected. The talc exposed populations were divided into three groups: (1) populations in which no other occupational carcinogen was mentioned (only talc millers satisfied this criterion); (2) populations of talc miners exposed to talc, quartz, and/or radon; and (3) other industrial populations in which talc is associated with quartz, nitrosamines, and asbestos depending on the study. No excess lung cancer mortality was found for the populations of talc millers exposed to high levels of talc but without any other potential carcinogen (SMR = 0.92, 42 cases) while the summary of mortality of talc miners exposed to quartz and/or radon was in excess (fixed effect SMR = 1.20, random effect RR = 1.85, 40 cases). Six studies in other industrial settings were identified. All reported increased lung cancer mortality among talc exposed workers but the talc exposure was confounded with other carcinogens and only one study was able to adjust on them. In conclusion, no increased lung cancer mortality was observed among talc millers despite their high exposure experience. In populations in which talc was associated with other potential carcinogens, some lung cancer excesses were observed.
Reported occupational respiratory diseases in Catalonia. R. Orriols, R. Costa, M. Albanell, et al. 2006;63(4):255-60. PubMed · Publisher · Free full text

Abstract

Objectives: A voluntary surveillance system was implemented in Catalonia (Spain) to ascertain the feasibility, incidence, and characteristics of occupational respiratory diseases and compare them with those of the compulsory official system.

Methods: In 2002, in collaboration with the Occupational and Thoracic Societies of Catalonia, occupational and chest physicians and other specialists were invited to report, on a bimonthly basis, newly diagnosed cases of occupational respiratory diseases. Information requested on each case included diagnosis, age, sex, place of residence, occupation, suspected agent, and physician's opinion on the likelihood that the condition was work related. Compulsory official system data derived from statistics on work related diseases for possible disability benefits declared by insurance companies, which are responsible for declaring these diseases to the Autonomous Government of Catalonia.

Results: Of 142 physicians seeing patients with occupational respiratory diseases approached, 102 (74%) participated. Three hundred and fifty nine cases were reported, of which asthma (48.5%), asbestos related diseases (14.5%), and acute inhalations (12.8%) were the most common. Physicians rated 63% of suspected cases as highly likely, 28% as likely, and 8% as low likelihood. The most frequent suspected agents reported for asthma were isocyanates (15.5%), persulphates (12.1%), and cleaning products (8.6%). Mesothelioma (5.9%) was the most frequent diagnosis among asbestos related diseases. The number of acute inhalations reported was high, with metal industries (26%), cleaning services (22%), and chemical industries (13%) being the most frequently involved. The frequency of occupational respiratory diseases recorded by this voluntary surveillance system was four times higher than that reported by the compulsory official system.

Conclusions: The compulsory scheme for reporting occupational lung diseases is seriously underreporting in Catalonia. A surveillance programme based on voluntary reporting by physicians may provide better understanding of the incidence and characteristics of these diseases. Persulphates and cleaning products, besides isocyanates, were the most reported causes of occupational asthma. Metal industries and cleaning services were the occupations most frequently involved in acute inhalations with a remarkably high incidence in our register.
Sixty years on: the price of assembling military gas masks in 1940. J.C. McDonald, J.M. Harris, G. Berry. 2006;63(12):852-5. PubMed · Publisher · Free full text

Abstract

Background: Between 1940 and 1944 military gas masks with filter pads containing 20% crocidolite were assembled in a Nottingham factory.

Methods: Records supplied by the late Professor Stephen Jones were of 1154 persons, mainly women, who had worked in the factory during this period; they included many deaths from mesothelioma. A systematic effort was therefore made to establish causes of death for the whole cohort.

Results: Of 640 employees with full name and sex recorded, 567 (89%) were traced. Of these, 491 had died, including 65 from mesothelioma, though only 54 were certified as such. After exclusion of these 54, standardised mortality ratios were significantly raised for respiratory cancer (SMR 2.5) and carcinomatosis (SMR 3.2). The pattern of mortality in the remaining 514 employees without full identification was similar, but a low tracing rate (40%) did not justify their further analysis. The first death from mesothelioma was in 1963 (22 years after first exposure) and the last in 1994, whereas a further 5.0 cases would have been expected between 1996 and 2003 (p = 0.0065).

Conclusion: These findings in a cohort followed over 60 years after brief exposure to crocidolite confirm a high and specific risk of mesothelioma (28% peritoneal) and perhaps of lung cancer some 20-50 years later. The statistically significant absence of further mesothelioma cases during the past eight years suggests that crocidolite, though durable, is slowly removed.
The French National Mesothelioma Surveillance Program. M. Goldberg, E. Imbernon, P. Rolland, et al. 2006;63(6):390-5. PubMed · Publisher · Free full text

Abstract

Objectives: The French National Mesothelioma Surveillance Program (NMSP) was established in 1998 by the National Institute for Health Surveillance (InVS). Its objectives are to estimate the trends in mesothelioma incidence and the proportion attributable to occupational asbestos exposure, to help improve its pathology diagnosis, to assess its compensation as an occupational disease, and to contribute to research.

Methods: The NMSP records incident pleural tumours in 21 French districts that cover a population of approximately 16 million people (a quarter of the French population). A standardised procedure of pathological and clinical diagnosis ascertainment is used. Lifetime exposure to asbestos and to other factors (man made mineral fibres, ionising radiation, SV40 virus) is reconstructed, and a case-control study was also conducted. The proportion of mesothelioma compensated as an occupational disease was assessed.

Results: Depending on the hypothesis, the estimated number of incident cases in 1998 ranged from 660 to 761 (women: 127 to 146; men: 533 to 615). Among men, the industries with the highest risks of mesothelioma are construction and ship repair, asbestos industry, and manufacture of metal construction materials; the occupations at highest risk are plumbers, pipe-fitters, and sheet-metal workers. The attributable risk fraction for occupational asbestos exposure in men was 83.2% (95% CI 76.8 to 89.6). The initial pathologist's diagnosis was confirmed in 67% of cases, ruled out in 13%, and left uncertain in the others; for half of the latter, the clinical findings supported a mesothelioma diagnosis. In all, 62% applied for designation of an occupational disease, and 91% of these were receiving workers' compensation.

Conclusions: The NMSP is a large scale epidemiological surveillance system with several original aspects, providing important information to improve the knowledge of malignant pleural mesothelioma, such as monitoring the evolution of its incidence, of high risk occupations and economic sectors, and improving pathology techniques.
The risk of lung cancer with increasing time since ceasing exposure to asbestos and quitting smoking. A. Reid, N.H. de Klerk, G.L. Ambrosini, et al. 2006;63(8):509-12. PubMed · Publisher · Free full text

Abstract

Objectives: To examine if the risk of lung cancer declines with increasing time since ceasing exposure to asbestos and quitting smoking, and to determine the relative asbestos effect between non-smokers and current smokers.

Methods: A cohort study of 2935 former workers of the crocidolite mine and mill at Wittenoom, who responded to a questionnaire on smoking first issued in 1979 and on whom quantitative estimates of asbestos exposure are known. Conditional logistic regression was used to relate asbestos exposure, smoking category, and risk of lung cancer.

Results: Eighteen per cent of the cohort reported never smoking; 66% of cases and 50% of non-cases were current smokers. Past smokers who ceased smoking within six years of the survey (OR = 22.1, 95% CI 5.6 to 87.0), those who ceased smoking 20 or more years before the survey (OR = 1.9, 95% CI 0.50 to 7.2), and current smokers (<20 cigarettes per day (OR = 6.8, 95% CI 2.0 to 22.7) or >20 cigarettes per day (OR = 13.2, 95% CI 4.1 to 42.5)) had higher risks of lung cancer compared to never smokers after adjusting for asbestos exposure and age. The asbestos effect between non-smokers and current smokers was 1.23 (95% CI 0.35 to 4.32).

Conclusion: Persons exposed to asbestos and tobacco but who subsequently quit, remain at an increased risk for lung cancer up to 20 years after smoking cessation, compared to never smokers. Although the relative risk of lung cancer appears higher in never and ex-smokers than in current smokers, those who both smoke and have been exposed to asbestos have the highest risk; this study emphasises the importance of smoking prevention and smoking cessation programmes within this high risk cohort.
Update of mortality and cancer incidence in the Australian petroleum industry cohort. R.T. Gun, N. Pratt, P. Ryan, et al. 2006;63(7):476-81. PubMed · Publisher · Free full text

Abstract

Objectives: To update the analysis of the cohort mortality and cancer incidence study of employees in the Australian petroleum industry.

Methods: Employees of Australian Institute of Petroleum member companies were enrolled in the cohort in four industry-wide surveys between 1981 and 1999. Mortality of 16,547 males and 1356 females was determined up to 31 December 2001 and cancer incidence to 31 December 2000. Cause specific mortality and cancer incidence were compared with those of the Australian population by means of standardised mortality ratios (SMRs) and standardised incidence ratios (SIRs). Associations between increased incidence of specific cancers and employment in the petroleum industry were tested by trends according to period of first employment, duration of employment, latency, and hydrocarbon exposure, adjusting for personal smoking history where appropriate.

Results: There was a significant elevation of the incidence of mesothelioma (SIR 1.77, 95% CI 1.05 to 2.79), melanoma (SIR 1.37, 95% CI 1.19 to 1.58), and prostate cancer (SIR 1.18, 95% CI 1.04 to 1.34). The SIRs of all leukaemias and of acute non-lymphocytic leukaemia (ANLL) were not significantly different from unity, but all 11 ANLL cases were clustered in the middle to high hydrocarbon exposure categories. Tanker drivers had a significantly elevated incidence of kidney cancer (12 cases v 5.84 expected, SIR 2.05, 95% CI 1.06 to 3.59). Lung cancer incidence was significantly reduced (SIR 0.69, 95% CI 0.57 to 0.83)

Conclusions: Most cases of mesothelioma are probably related to past exposure to asbestos in refineries. No occupational cause has been identified for the excess of melanoma, or prostatic or bladder cancer. The possibility of a causal relationship between cancer of the kidney and hydrocarbon exposure warrants further study. It is uncertain whether benzene exposures, particularly past levels of exposure, have been high enough to cause ANLL.
Are lung and pleural benign asbestos induced diseases a preliminary step in the pathogenic process of mesothelioma and lung cancer development?. M. Goldberg. 2005;62(10):663-4. Comment PubMed · Publisher · Free full text

Summary

In this commentary, the author discussed whether benign asbestos-related lung and pleural diseases (pleural plaques, pleural calcification and thickening, and asbestosis) are a preliminary step towards malignant mesothelioma and lung cancer, or whether their association with these cancers only reflects a common cause, asbestos exposure. He described three hypotheses tested in epidemiological studies: a single sequential pathogenic process, a common cause without interaction, and a common cause with interaction. He reported that animal data gave some support to fibrosis preceding cancer but had limitations, and that cohort and case-control studies had given inconsistent results. He then discussed the study by Reid et al, published in the same issue, of former workers and residents of Wittenoom exposed to crocidolite. That study found that, for the same level of asbestos exposure, the risk of pleural mesothelioma did not differ between subjects with and without radiological signs of lung and pleural fibrosis, whereas the risk of peritoneal mesothelioma was higher in those with such signs. He considered this to favour the common cause without interaction hypothesis for pleural mesothelioma, and to give some strength to the common cause with interaction hypothesis for peritoneal mesothelioma. He noted open questions: exposure was to crocidolite only, the higher exposures may have been underestimated, and benign chest diseases may have been underestimated. He concluded that the mechanisms remain open. He said this matters because some countries compensate asbestos-induced cancers only in patients with chest abnormalities.

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Cancer incidence among Danish seafarers: a population based cohort study. L. Kaerlev, J. Hansen, H.L. Hansen, et al. 2005;62(11):761-5. PubMed · Publisher · Free full text

Abstract

Aims: Seafarers aboard oil and chemical tankers may be exposed to many chemicals, including substances like benzene that are known to be carcinogenic. Other seafarers are exposed to engine exhaust, different oil products, and chemicals used aboard and some years ago asbestos was also used extensively in ships. The aim of this study was to study cancer morbidity among Danish seafarers in relation to type of ship and job title.

Methods: A cohort of all Danish seafarers during 1986-1999 (33,340 men; 11,291 women) registered by the Danish Maritime Authority with an employment history was linked with the nationwide Danish Cancer Registry and followed up for cancer until the end of 2002. The number of person years at risk was 517,518. Standardised incidence ratios (SIR) were estimated by use of the corresponding national rates.

Results: The SIR of all cancers combined was higher than expected: 1.26 (95% CI 1.19 to 1.32) for men and 1.07 (95% CI 0.95 to 1.20) for women. This was mainly due to an excess of cancer of the larynx, lung, tongue, mouth, pharynx, oesophagus, pancreas, kidney, urinary bladder, colon, and bone as well as skin melanomas among men (the three latter borderline significantly increased), and an excess of cancer of the lung, rectum, and cervix uteri among women. The differences in risk pattern for lung cancer between the different job categories among men ranged in terms of SIR from 1.2 (95% CI 0.9 to 1.7) (engine officers) to 2.3 (1.6 to 3.3) (engine room crew), and 4.1 (2.1 to 7.4) among maintenance crew. Non-officers had a 1.5 times higher lung cancer risk than officers. No increased occurrence of all lymphatic and haematopoietic malignancies combined was found for employees on tankers, but the number of cases was limited to a total of 7.

Conclusions: Danish seafarers, especially men, face an increased overall cancer risk, in particular a risk for lung cancer and other tobacco associated cancers.
Cancer risks in a historical UK cohort of benzene exposed workers. T. Sorahan, L.J. Kinlen, R. Doll. 2005;62(4):231-6. PubMed · Publisher · Free full text

Abstract

Aims: To examine mortality from different causes and cancer incidence among a cohort of benzene workers in England and Wales.

Methods: A cohort of 5514 workers who had been occupationally exposed to benzene in 1966/67 or earlier was assembled by the former Factory Inspectorate and the Medical Research Council from details provided by 233 employers in England and Wales. The cohort was followed up for mortality (1968-2002) and cancer registrations (1971-2001). National mortality rates and cancer registration (incidence) rates were used to calculate standardised mortality ratios and standardised registration ratios.

Results: Mortality was close to expectation for all causes and significantly increased for cancer of the lip, cancer of the lung and bronchus, secondary and unspecified cancers, acute non-lymphocytic leukaemia (ANLL), and all neoplasms. Significant deficits were shown for three non-malignant categories (mental disorders, diseases of the digestive system, accidents). SMRs for other leukaemia, lymphomas, and multiple myeloma were close to or below expectation. There was some evidence of under-ascertainment of cancer registrations, although significantly increased SRRs were shown for lung cancer and cancer of the pleura (mesothelioma).

Conclusions: Many study subjects would have been exposed to carcinogens other than benzene (for example, asbestos, rubber industry fumes, foundry fumes, polycyclic aromatic hydrocarbons), and the excesses of lung cancer and mesothelioma are likely to reflect exposures to these other carcinogens. The carcinogenic effects of benzene exposure on the lymphohaematopoietic system were limited to ANLL.
Changing trends in US mesothelioma incidence. M. Greenberg. 2005;62(2):134. Comment · Letter PubMed · Publisher · Free full text

Summary

In this letter, the author responded to a paper by Weill, Hughes and Churg (Occup Environ Med 2004;61:438–41). That paper had associated a decline in US mesothelioma incidence with an earlier decline in amphibole asbestos use. The author argued that public health policy makers should read the paper with great circumspection and should not conclude that the asbestos problem had been largely solved. He stated that expert opinion published by WHO, ILO and IARC was less sanguine about chrysotile, and that its safe use was increasingly acknowledged not to be reasonably practicable. He cautioned against reading the authors' statement that asbestosis and asbestos-attributable lung cancer are linked as implying that pulmonary fibrosis is a necessary stage in cancer development. He cited an expert consensus that this sequence was not necessary, and experimental and tissue culture evidence that all asbestos species induce malignant change apart from fibrosis. He criticised the chain of reviews relied on for the 'biological plausibility' of chrysotile being less potent than amphiboles. He questioned the authors' explanation of lower US than UK mesothelioma rates, citing US amphibole imports for 1964 and 1965 (amosite 23 932 and 17 042 tonnes; crocidolite 21 163 and 17 042 tonnes) and UK 1965 imports (amosite 22 582, crocidolite 3425 tonnes). He argued that national import tonnages and whole-population denominators were poor surrogates for exposure of at-risk groups. Noting that the USA exposed its workforce to some 25 million tonnes of asbestos between 1900 and 2002, he concluded that service workers, construction workers and bystanders would remain at risk and that policy makers should maintain a watching brief for many years.

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Monitoring of fluoro-edenite fibre pollution through the study of sheep lymph nodes as a model of a biological indicator. V. Rapisarda, G. Rapisarda, G.D. Vico, et al. 2005;62(9):656. Letter PubMed · Publisher · Free full text

Summary

The authors examined whether sheep lymph nodes could serve as a biological indicator of environmental pollution by fluoro-edenite, a fibrous amphibole found in material from a stone quarry near Biancavilla, on the south-west slope of Mt Etna, Sicily. Mortality from pleural mesothelioma in Biancavilla had been reported as significantly increased, comparable to asbestos-exposed cohorts, and attributed to fluoro-edenite exposure. Sixty healthy sheep, randomly selected from six flocks (10 per flock) habitually grazing 3 km from the town, and 10 control sheep were sacrificed. Lymph nodes draining the lung lobes (tracheobronchial and one middle mediastinal node) were examined by histology, light and scanning electron microscopy, and energy dispersion spectrometry x ray analysis. Histology showed hyperplasia of lymphoid follicles with large reactive cores, and numerous macrophages containing grey-brownish particulate with fibril-structured elements. Electron microscopy of digested nodes showed fibres with the crystallochemical features of fluoro-edenite. Their dimensions were similar to those described in the lung of a Biancavilla housewife who died of pleural mesothelioma. Fibres were found in all exposed animals and never in control nodes. Mean fibre numbers did not differ significantly among exposed animals. The authors described the results as preliminary and said they documented a risk of inhaling fluoro-edenite fibres a few kilometres from the town. They concluded that measuring these fibres in sheep lymph nodes appeared to be a helpful tool for environmental monitoring.

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Municipal pleural cancer mortality in Spain. G. López-Abente, V. Hernández-Barrera, M. Pollán, et al. 2005;62(3):195-9. PubMed · Publisher · Free full text

Abstract

Background: Pleural cancer is a recognised indicator of exposure to asbestos and mesothelioma mortality.

Aims: To investigate the distribution of municipal mortality due to this tumour, using the autoregressive spatial model proposed by Besag, York, and Mollie.

Methods: It was possible to compile and ascertain the posterior distribution of relative risk on the basis of a single Bayesian spatial model covering all of Spain's 8077 municipal areas. Maps were plotted depicting standardised mortality ratios, smoothed relative risk (RR) estimates, and the distribution of the posterior probability that RR >1.

Results: There was a higher risk of death due to pleural cancer in well defined towns and areas, many of which correspond to municipalities where asbestos using industries once existed for many years, the prime example being the municipal pattern registered for Barcelona Province. The quality of mortality data, the suitability of the model used, and the usefulness of municipal atlases for environmental surveillance are discussed.
Non-malignant consequences of decreasing asbestos exposure in the Brazil chrysotile mines and mills. E. Bagatin, J.A. Neder, L.E. Nery, et al. 2005;62(6):381-9. PubMed · Publisher · Free full text

Abstract

Aims: To investigate the consequences of improvement in the workplace environment over six decades (1940-96) in asbestos miners and millers from a developing country (Brazil).

Methods: A total of 3634 Brazilian workers with at least one year of exposure completed a respiratory symptoms questionnaire, chest radiography, and a spirometric evaluation. The study population was separated into three groups whose working conditions improved over time: group I (1940-66, n = 180), group II (1967-76, n = 1317), and group III (1977-96, n = 2137).

Results: Respiratory symptoms were significantly related to spirometric abnormalities, smoking, and latency time. Breathlessness, in particular, was also associated with age, pleural abnormality and increased cumulative exposure to asbestos fibres. The odds ratios (OR) for parenchymal and/or non-malignant pleural disease were significantly lower in groups II and III compared to group I subjects (0.29 (0.12-0.69) and 0.19 (0.08-0.45), respectively), independent of age and smoking status. Similar results were found when groups were compared at equivalent latency times (groups I v II: 30-45 years; groups II v III: 20-25 years). Ageing, dyspnoea, past and current smoking, and radiographic abnormalities were associated with ventilatory impairment. Lower spirometric values were found in groups I and II compared to group III: lung function values were also lower in higher quartiles of latency and of cumulative exposure in these subjects.

Conclusions: Progressive improvement in occupational hygiene in a developing country is likely to reduce the risk of non-malignant consequences of dust inhalation in asbestos miners and millers.
Occupation and risk of stomach cancer in Poland. S. Krstev, M. Dosemeci, J. Lissowska, et al. 2005;62(5):318-24. PubMed · Publisher · Free full text

Abstract

Background: In spite of the dramatic decline in the incidence of stomach cancer in the twentieth century, Poland has one of the highest rates in the world.

Aims: To evaluate the risk of stomach cancer by grouped occupations and industries, as well as by some specific occupational exposures.

Methods: Cases (n = 443) were newly diagnosed with stomach adenocarcinomas between 1994 and 1996. Controls (n = 479) were randomly selected from the general population in Warsaw.

Results: Only a few occupations and industries were associated with significantly increased risks of stomach cancer. The most suggestive finding was for work in the leather goods industry. Risk was also significantly increased among men working in fabricated metal production and among women ever employed as managers and governmental officials. Men ever employed as teaching professionals and women employed as technical and science professionals had significantly decreased risks of stomach cancer. Among men, a significant positive trend in risk with duration of employment was observed for work in the leather industry and special trade construction. No significantly increased risks were observed for specific exposures assessed by a job-exposure matrix or by self-reports. However among men there were non-significantly increased risks with 10 or more years exposure to asbestos, metal dust, and nitrosamines assessed by a job-exposure matrix.

Conclusions: Employment in the leather goods industry, special trade construction, and metal fabrication was associated with an increased risk of stomach cancer among men. However, there were only weak associations with specific exposures. Occupational exposures do not contribute substantially to the high rates of stomach cancer in Poland.
The additional risk of malignant mesothelioma in former workers and residents of Wittenoom with benign pleural disease or asbestosis. A. Reid, N. de Klerk, G. Ambrosini, et al. 2005;62(10):665-9. PubMed · Publisher · Free full text

Abstract

Aims: To examine the hypothesis that people with benign pleural disease or asbestosis have an increased risk of malignant mesothelioma beyond that attributable to their degree of asbestos exposure.

Methods: Former workers and residents of the crocidolite mining and milling town of Wittenoom are participating in a cancer prevention programme (n = 1988). The first plain chest radiograph taken at the time of recruitment into the cancer prevention programme was read for evidence of benign pleural disease and asbestosis, using the UICC classification. Crocidolite exposure of former workers was derived from employment records and records of dust measurements performed during the operation of the asbestos mine and mill between 1943 and 1966. Based on fibre counts, exposure for former residents was determined using duration of residence and period of residence (before and after a new mill was commissioned in 1957) and interpolation from periodic hygienic measures undertaken from personal monitors between 1966 and 1992. Cox proportional hazards modelling was used to relate benign pleural disease, asbestosis, asbestos exposure, and mesothelioma.

Results: Between 1990 and 2002, there were 76 cases of mesothelioma (56 of the pleura and 20 of the peritoneum). Cases had more radiographic evidence of (all) benign pleural disease, pleural thickening, blunt/obliterated costophrenic angle, and asbestosis than non-cases. Adjusting for time since first exposure (log years), cumulative exposure (log f/ml-years), and age at the start of the programme, pleural thickening (OR = 3.1, 95% CI 1.2 to 7.6) and asbestosis (OR = 3.3, 95% CI 1.3 to 8.6) were associated with an increased risk of peritoneal mesothelioma. There was no increased risk for pleural mesothelioma.

Conclusion: The presence of benign pleural disease, in particular pleural thickening, and asbestosis appears to increase the risk of mesothelioma of the peritoneum, but not of the pleura beyond that attributable to indices of asbestos exposure in this cohort of subjects exposed to crocidolite.
The effect of asbestosis on lung cancer risk beyond the dose related effect of asbestos alone. A. Reid, N. de Klerk, G.L. Ambrosini, et al. 2005;62(12):885-9. PubMed · Publisher · Free full text

Abstract

Aims: To determine if the presence of asbestosis is a prerequisite for lung cancer in subjects with known exposure to blue asbestos (crocidolite).

Methods: Former workers and residents of Wittenoom with known amounts of asbestos exposure (duration, intensity, and time since first exposure), current chest x ray and smoking information, participating in a cancer prevention programme (n = 1988) were studied. The first plain chest radiograph taken at the time of recruitment into the cancer prevention programme was examined for radiographic evidence of asbestosis according to the UICC (ILO) classification. Cox proportional hazards modelling was used to relate asbestosis, asbestos exposure, and lung cancer.

Results: Between 1990 and 2002 there were 58 cases of lung cancer. Thirty six per cent of cases had radiographic evidence of asbestosis compared to 12% of study participants. Smoking status was the strongest predictor of lung cancer, with current smokers (OR = 26.5, 95% CI 3.5 to 198) having the greatest risk. Radiographic asbestosis (OR = 1.94, 95% CI 1.09 to 3.46) and asbestos exposure (OR = 1.21 per f/ml-year, 95% CI 1.02 to 1.42) were significantly associated with an increased risk of lung cancer. There was an increased risk of lung cancer with increasing exposure in those without asbestosis.

Conclusion: In this cohort of former workers and residents of Wittenoom, asbestosis is not a mandatory precursor for asbestos related lung cancer. These findings support the hypothesis that it is the asbestos fibres per se that cause lung cancer, which can develop with or without the presence of asbestosis.
A cohort study of mortality among Ontario pipe trades workers. M.M. Finkelstein, D.K. Verma. 2004;61(9):736-42. PubMed · Publisher · Free full text

Abstract

Aims: To study mortality in a cohort of members of the United Association of Journeymen and Apprentices of the Plumbing and Pipe Fitting Industry of the United States and Canada and to compare results with two previous proportional mortality studies.

Methods: A cohort of 25,285 workers who entered the trade after 1949 was assembled from records of the international head office. Mortality was ascertained by linkage to the Canadian Mortality Registry at Statistics Canada. Standardised mortality ratios were computed using Ontario general population mortality rates as the reference.

Results: There were significant increases in lung cancer mortality rates (SMR 1.27; 95% CI 1.13 to 1.42). Increased lung cancer risk was observed among plumbers, pipefitters, and sprinkler fitters. Increased risk was observed among workers joining the Union as late as the 1970s. A random effects meta-analysis of this study and the two PMR studies found significant increases in oesophageal (RR 1.24; 95% CI 1.00 to 1.53), lung (RR 1.31; 95% CI 1.19 to 1.44), and haematological/lymphatic (RR 1.21; 95% CI 1.08 to 1.35) malignancies.

Conclusions: The mortality pattern is consistent with the effects of occupational exposure to asbestos. Increased risk due to other respiratory carcinogens such as welding fume cannot be excluded. There are substantial amounts of asbestos in place in industrial and commercial environments. The education and training of workers to protect themselves against inhalation hazards will be necessary well into the future.
A mortality cohort study among workers in a graphite electrode production plant in Italy. D.F. Merlo, S. Garattini, U. Gelatti, et al. 2004;61(2):e9. PubMed · Publisher · Free full text

Abstract

Background: Graphite electrode manufacturing workers are exposed to coal tar and its volatiles containing a variety of polycyclic aromatic hydrocarbons (PAH), silica and graphite dusts, and asbestos.

Aims: To investigate mortality from cancer and other diseases among workers in a graphite electrode production plant in Italy.

Methods: A total of 1291 males actively employed between 1 January 1950 and 31 December 1989 who had worked at the plant for at least one year were studied. The follow up extended from 1950 to 1997. Standardised mortality ratios (SMR) and their 95% confidence intervals (CI) were computed using mortality rates for the Italian and regional male population.

Results: Excess mortality was observed for all causes (SMR 1.44, CI 1.32 to 1.56), all cancers (SMR 1.27, CI 1.07 to 1.50), liver cancer (SMR 4.19, CI 2.68 to 6.23), silicosis (SMR 66.39, CI 52.56 to 82.7), and cirrhosis and other chronic diseases of the liver (SMR 1.87, CI 1.31 to 2.59) in comparison with the national male population. When regional rates were used to calculate the number of expected deaths, SMRs remained higher for silicosis (SMR 57.32, 42.11 to 76.22), and liver cancer (SMR 2.57, 1.57 to 3.97). Mortality from silicosis was increased in workers hired at young ages (<25 years, SMR 81.79; 25-34 years, SMR 82.73), and in workers aged <45 at death (SMR 333.3, CI 159.8 to 613). Mortality from liver cancer increased threefold (SMR 3.11, CI 1.78 to 5.05) in workers with more than 10 years of employment at the plant during the manufacture of Karbate products.

Conclusions: Results support the association between excess mortality from silicosis and occupational exposure to siliceous sands experienced during graphite electrode manufacturing. The observed excess mortality from liver cancer is compatible, to some extent, with exposures that may have occurred during the manufacture of phenolic and furfuryl resins treated products, although a role of lifestyle factors and viral infections cannot be excluded.
All-cause and cause specific mortality in a cohort of 20 000 construction workers; results from a 10 year follow up. V. Arndt, D. Rothenbacher, U. Daniel, et al. 2004;61(5):419-25. PubMed · Publisher · Free full text

Abstract

Background: Construction workers are potentially exposed to many health hazards, including human carcinogens such as asbestos, silica, and other so-called "bystander" exposures from shared work places. The construction industry is also a high risk trade with respect to accidents.

Methods: A total of 19 943 male employees from the German construction industry who underwent occupational health examinations between 1986 and 1992 were followed up until 1999/2000.

Results: A total of 818 deaths occurred during the 10 year follow up (SMR 0.71; 95% CI 0.66 to 0.76). Among those were 299 deaths due to cancer (SMR 0.89; 95% CI 0.79 to 1.00) and 312 deaths due to cardiovascular diseases (SMR 0.59; 95% CI 0.51 to 0.68). Increased risk of mortality was found for non-transport accidents (SMR 1.61; 95% CI 1.15 to 2.27), especially due to falls (SMR 1.87; 95% CI 1.18 to 2.92) and being struck by falling objects (SMR 1.90; 95% CI 0.88 to 3.64). Excess mortality due to non-transport accidents was highest among labourers and young and middle-aged workers. Risk of getting killed by falling objects was especially high for foreign workers (SMR 4.28; 95% CI 1.17 to 11.01) and labourers (SMR 6.01; 95% CI 1.63 to 15.29).

Conclusion: Fatal injuries due to falls and being struck by falling objects pose particular health hazards among construction workers. Further efforts are necessary to reduce the number of fatal accidents and should address young and middle-aged, semi-skilled and foreign workers, in particular. The lower than expected cancer mortality deserves careful interpretation and further follow up of the cohort.
Changing trends in US mesothelioma incidence. H. Weill, J.M. Hughes, A.M. Churg. 2004;61(5):438-41. PubMed · Publisher · Free full text

Abstract

Aims: To report the temporal pattern and change in trend of mesothelioma incidence in the United States since 1973.

Methods: The Surveillance, Epidemiology, and End Results (SEER) programme of the National Cancer Institute has since 1973 provided annual age adjusted incidence for mesothelioma in representative cancer registries dispersed throughout the USA. SEER data are analysed to describe the trend of male mesothelioma incidence in the USA.

Results: The US male mesothelioma incidence data indicate that after two decades of increasing incidence, a likely decline has been observed since the early 1990s, when a highly significant change in the upward course occurred.

Conclusions: Increasing male mesothelioma incidence for many years was undoubtedly the result of exposure to asbestos. The high mesothelioma risk was prominently influenced by exposure to amphibole asbestos (crocidolite and amosite), which reached its peak usage in the 1960s and thereafter declined. A differing pattern in some other countries (continuing rise in incidence) may be related to their greater and later amphibole use, particularly crocidolite. The known latency period for the development of this tumour provides biological plausibility for the recent decline in mesothelioma incidence in the USA. This favourable finding is contrary to a widespread fear that asbestos related health effects will show an inevitable increase in coming years, or even decades.
Malignant pleural and peritoneal mesotheliomas in former miners and millers of crocidolite at Wittenoom, Western Australia. G. Berry, N.H. de Klerk, A. Reid, et al. 2004;61(4):e14. PubMed · Publisher · Free full text

Abstract

Aims: To report the number of malignant pleural and peritoneal mesotheliomas that have occurred in former Wittenoom crocidolite workers to the end of 2000, and to compare this with earlier predictions.

Methods: A group of 6493 men and 415 women who had worked at the former Wittenoom crocidolite mine and mill at some time between 1943 and 1966 have been followed up throughout Australia and Italy to the end of 2000.

Results: The cumulative number of mesotheliomas up to 2000 was 235 in men (202 pleural, 33 peritoneal) and seven (all pleural) in women. There had been 231 deaths with mesothelioma (9% of known deaths).

Conclusions: The number of deaths in men with mesothelioma between 1987 and 2000 was at the low end of the predictions made earlier based on the number of cases to 1986. If this trend continues, it is predicted that about another 110 deaths with mesothelioma will occur in men by 2020.
Mortality and cancer incidence among Lithuanian cement producing workers. G. Smailyte, J. Kurtinaitis, A. Andersen. 2004;61(6):529-34. PubMed · Publisher · Free full text

Abstract

Aims: To investigate mortality and cancer incidence of cement producing workers.

Methods: A total of 2498 cement workers who have been employed at Portland cement producing departments for at least one year from 1956 to 2000 were followed up from 1 January 1978 to 31 December 2000. The cohort contributed 43,490 person-years to the study. Standardised incidence ratios (SIR) and standardised mortality ratios (SMR) were calculated as ratios between observed and expected numbers of cancers and deaths. The expected numbers were based on sex specific incidence and mortality rates for the total Lithuanian population.

Results: Significantly increased SMRs were found for all malignant neoplasms (SMR 1.3, 95% CI 1.0 to 1.5) and for lung cancer (SMR 1.4, 95% CI 1.0 to 1.9) among male cement workers. SIR for all cancer sites was 1.2 (95% CI 1.0 to 1.4). Excess risk was found for cancer of the lung (SIR 1.5, 95% CI 1.1 to 2.1). The SIR for urinary bladder cancer was also increased (SIR 1.8, 95% CI 0.9 to 3.5). The overall cancer incidence was not increased among females (SIR 0.8, 95% CI 0.6 to 1.1). With increasing cumulated exposure to cement dust, there were indications of an increasing risk of lung and stomach cancers among males.

Conclusions: This study supported the hypothesis that exposure to cement dust may increase the lung and bladder cancer risk. A dose related risk was found for stomach cancer, but no support was found for an increased risk of colorectal cancer.
Mortality in a cohort of vermiculite miners exposed to fibrous amphibole in Libby, Montana. J.C. McDonald, J. Harris, B. Armstrong. 2004;61(4):363-6. PubMed · Publisher · Free full text

Abstract

Background: Fibrous tremolite is a widespread amphibole asbestiform mineral, airborne fibres of which constitute an environmental hazard in Libby, Montana, northern California, and elsewhere.

Aims: To determine excess risk from lung cancer, mesothelioma, and all-cause mortality in a cohort of men exposed to tremolite, but no other form of asbestos.

Methods: Mortality by certified cause and various measures of exposure to tremolite and related amphibole fibres was assessed in a cohort of 406 vermiculite mineworkers in Libby, Montana, employed before 1963 and followed until 1999.

Results: Total deaths were: lung cancer 44 (SMR 2.40), non-malignant respiratory disease (NMRD) 51 (SMR 3.09), all causes 285 (SMR 1.27); included among the total were 12 deaths ascribed to mesothelioma (4.21% of all deaths). Adjusted linear increments in relative risks (per 100 f/ml.y), estimated by Poisson regression, were: lung cancer (0.36, 95% CI 0.03 to 1.20), NMRD (0.38, 95% CI 0.12 to 0.96), and all deaths (0.14, 95% CI 0.05 to 0.26).

Conclusions: The all-cause linear model would imply a 14% increase in mortality for mine workers exposed occupationally to 100 f/ml.y or about 3.2% for a general population exposed for 50 years to an ambient concentration of 0.1 f/ml. Amphibole fibres, tremolite in particular, are likely to be disproportionately responsible for cancer mortality in persons exposed to commercial chrysotile, but to what extent cannot be readily assessed.
Mortality of employees of the United Kingdom Atomic Energy Authority, 1946-97. W.D. Atkinson, D.V. Law, K.J. Bromley, et al. 2004;61(7):577-85. PubMed · Publisher · Free full text

Abstract

Background: The workforce of the UK Atomic Energy Authority has been the subject of several previous epidemiological investigations.

Aims: To detect and investigate associations between mortality rates and employment in a substantially increased cohort size and follow up extended to 1997.

Methods And Results: The new cohort included 51 367 employees, of whom 10 249 were dead. Mortality rates for all workers were low compared to national rates, as were rates in radiation workers and for workers monitored for internal contamination. For radiation workers all cause mortality and all cancer mortality were significantly lower than for non-radiation workers. There was no overall trend of increasing mortality with radiation dose. There was little evidence of raised mortality from leukaemia. The association of prostatic cancer with radiation dose was much less significant than in previous reports. However, the relatively high mortality from uterine cancers among radiation workers remained, though the numbers were very small. The association was with endometrial rather than cervical cancer. Mortality from cancer of the pleura was high among radiation workers, but was not correlated with dose.

Conclusion: Overall, radiation workers at UKAEA showed no excess mortality. The previously detected association of prostate cancer with high radiation dose may have been a statistical artefact or a risk associated with discontinued activities. Endometrial cancer occurred at higher rates in female radiation workers, but, because there was no correlation with dose, may well be due to something other than their radiation exposure. Cancer of the pleura in radiation workers was almost certainly related to past asbestos exposure.
Occupational and environmental exposures and lung cancer in an industrialised area in Italy. V. Fano, P. Michelozzi, C. Ancona, et al. 2004;61(9):757-63. PubMed · Publisher · Free full text

Abstract

Aims: To investigate the effects of occupational exposures and residence near to industrial sites on lung cancer mortality in an area in Italy.

Methods: 234 cases of lung cancer and 729 controls matched by sex, age, and date of death were enrolled. Environmental exposure was evaluated using historical residence data. A geographical information system was used to compute distances from residence to pollution source (cement factory, power plants, harbour) and an average distance was computed for each subject. Odds ratios (OR) and 95% confidence intervals (CI) in a logistic regression model were used to estimate the relative risk of lung cancer associated with the risk factors (smoking habits and occupational exposure) collected by questionnaire; ORs for distances from pollution sources and from city centre were computed, adjusting for smoking habits, education, and occupation.

Results: Smoking habits (< or =10 cigarettes/day, OR = 2.28; 11-20, OR = 4.64; >20, OR = 6.61) and occupational exposure to asbestos (OR = 3.50) were significantly associated with lung cancer risk. Reported traffic level of area of residence and residence near the four sources were not associated with increased risk of lung cancer. There was a significantly increased risk for those residing outside the city centre, in the southern outskirts (OR = 1.51).

Conclusions: The increased lung cancer risk observed in the area can partly be explained by occupational exposures. The increased risk in the outskirts of the city is consistent with the results of dispersion models that indicate high levels of pollutant deposition in the same area.
Occupations and exposures in the work environment as determinants for rheumatoid arthritis. A.R. Olsson, T. Skogh, O. Axelson, et al. 2004;61(3):233-8. PubMed · Publisher · Free full text

Abstract

Background And Aims: Several occupational categories have been associated with rheumatoid arthritis (RA); this study was conducted to further evaluate these associations.

Methods: Lifelong occupational history together with exposure experiences were collected through a postal questionnaire answered by 293 incident cases and 1346 population based referents. Occupational determinants were evaluated through stratified and multivariate analyses; pooled analyses with previously gathered data on 422 prevalent cases and 858 referents were also performed.

Results: In both materials, significantly increased logistic odds ratios (LORs) were seen for male conductors, freight and transport workers (LOR 17.8, 95% CI 1.5 to 207.8 and LOR 4.7, 95% CI 1.4 to 16.3, respectively), and farmers and farm workers (LOR 2.4, 95% CI 1.1 to 5.2, and LOR 2.2, 95% CI 1.3 to 3.5, respectively). Among women, increased LORs were seen in the separate and the pooled material for printmakers and process engravers (LOR 5.5, 95% CI 0.9 to 32.6, and LOR 3.0, 95% CI 0.9 to 10.3, respectively). Increased risks were seen in both materials for men exposed to asbestos (LOR 2.5, 95% CI 1.0 to 6.8, and LOR 1.6, 95% CI 0.8 to 3.3, respectively), and vibrations (LOR 2.0, 95% CI 0.9 to 4.4, and LOR 2.2, 95% CI 1.3 to 3.8, respectively). The risk for RA increased with increasing duration of exposure to vibrations and mineral dust, respectively.

Conclusions: There was evidence of a causal relation between exposures to vibrations and mineral dust and development of RA among men. Occupational factors seem to be aetiologically more important for men, and most occupations at risk involve multiple exposures. Several exposures associated with an increased risk for RA are frequent among farmers, and some of the occupations at risk include exposure to organic dust.
Update of a prospective study of mortality and cancer incidence in the Australian petroleum industry. R.T. Gun, N.L. Pratt, E.C. Griffith, et al. 2004;61(2):150-6. PubMed · Publisher · Free full text

Abstract

Aims: To update the analysis of the cohort mortality and cancer incidence study of employees in the Australian petroleum industry.

Methods: Employees from 1981 to 1996 were traced through the Australian National Death Index and the National Cancer Statistics Clearing House. Cause specific mortality and cancer incidence were compared with those of the Australian population by means of standardised mortality ratios (SMRs) and standardised incidence ratios (SIRs). Associations between increased incidence of specific cancers and employment in the petroleum industry were tested by trends according to period of first employment, duration of employment, latency, and hydrocarbon exposure, adjusting for personal smoking history where appropriate. Total follow up time was 176 598 person-years for males and 10 253 person-years for females.

Results: A total of 692 of the 15 957 male subjects, and 16 of the 1206 female subjects had died by the cut off date, 31 December 1996. In males, the all-cause SMR and the SMRs for all major disease categories were significantly below unity. There was a non-significant increase of the all-cancer SIR (1.04, 95% CI 0.97 to 1.11). There was a significant increase of the incidence of melanoma (SIR 1.54, 95% CI 1.30 to 1.81), bladder cancer (SIR 1.37, 95% CI 1.00 to 1.83), and prostate cancer (SIR 1.19, 95% CI 1.00 to 1.40), and a marginally significant excess of pleural mesothelioma (SIR 1.80, 95% CI 0.90 to 3.22), leukaemia (SIR 1.39, 95%CI 0.91 to 2.02), and multiple myeloma (SIR 1.72, 95% CI 0.96 to 2.84).

Conclusions: Most cases of mesothelioma are probably related to past exposure to asbestos in refineries. The melanoma excess may be the result of early diagnosis. The excess bladder cancer has not been observed previously in this industry and is not readily explained. The divergence between cancer incidence and cancer mortality suggests that the "healthy worker effect" may be related to early reporting of curable cancers, leading to increased likelihood of cure and prolonged mean survival time.
Asbestos related diseases from environmental exposure to crocidolite in Da-yao, China. I. Review of exposure and epidemiological data. S. Luo, X. Liu, S. Mu, et al. 2003;60(1):35-41; discussion 41-2. Review PubMed · Publisher · Free full text

Abstract

Background: Scattered patches of crocidolite, one form of asbestos, were found in the surface soil in the rural county of Da-yao in southwestern China. In 1983, researchers from the West China University of Medical Sciences (WCUMS) discovered that residents of two villages in Da-yao had hyperendemic pleural plaques and excessive numbers of pleural mesotheliomas.

Aims: To review and summarise epidemiological studies, along with other relevant data, and to discuss the potential contribution to environmental risk assessment.

Methods: This report is based on a review of several clinical/epidemiological studies conducted by WCUMS researchers since 1984, which included one cross sectional medical examination survey, one clinical/pathological analysis of 46 cases of mesothelioma, and three retrospective cohort mortality studies. Additional information acquired from reviewing original data first hand during a personal visit along with an interview of medical specialists from Da-yao County Hospital was also incorporated.

Results: The prevalence of pleural plaque was 20% among peasants in Da-yao over 40 years of age in the cross sectional survey. The average number of mesothelioma cases was 6.6 per year in the 1984-95 period and 22 per year in the 1996-99 period, in a population of 68 000. For those mesothelioma cases that were histology confirmed, there were 3.8 cases/year in the first period and 9 cases/year in the second. Of the 2175 peasants in this survey, 16 had asbestosis. Lung cancer deaths were significantly increased in all three cohort studies. The annual mortality rate for mesothelioma was 85 per million, 178 per million, and 365 per million for the three cohort studies, respectively. The higher exposed peasants had a fivefold increased mesothelioma mortality compared to their lower exposed counterparts. There were no cases of mesothelioma in the comparison groups where no crocidolite was known to exist in the environment. In the third cohort study, almost one of five cancer deaths (22%) was from mesothelioma. The ratio of lung cancer to mesothelioma deaths was low for all three studies (1.3, 3.0, and 1.2, respectively).

Conclusions: The observation of numerous mesothelioma cases at Da-yao was a unique finding, due mainly to their lifetime exposure to crocidolite asbestos. The finding of cases dying at a younger age and the relatively high ratio of mesothelioma cases to lung cancer could also be another unique result of lifetime environmental exposure to crocidolite asbestos. Although the commercial use of crocidolite has been officially banned since 1984, the incidence of mesothelioma has continued to show a steady increase, particularly among peasants. Since the latency of mesothelioma is approximately 30-40 years, the ban had little effect in the 1990s. The increased awareness and changes in diagnosis over time may also contribute to the increase. Furthermore, exposure to asbestos stoves and walls continued. The government implemented reduction of these exposures. However, from a public health standpoint, the most important issue is the complete avoidance of further exposure to asbestos.
Earlier study on asbestos workers, ILO scores, and oxygenation more comprehensive. D.D. Smith. 2003;60(8):611; author reply 611. Comment · Letter PubMed · Publisher · Free full text
Evaluation of the quality of coding of job episodes collected by self questionnaires among French retired men for use in a job-exposure matrix. C. Pilorget, E. Imbernon, M. Goldberg, et al. 2003;60(6):438-43. PubMed · Publisher · Free full text

Abstract

Background: and

Aims: The ESPACES study was intended to identify retirees who may have been, according to their job descriptions, exposed to asbestos during their working lives. As part of this study, we analysed the quality of the occupation and activity sector coding as well as its effect on the subjects' exposure status.

Methods: The occupation and activity sector for a sample of 450 retired men were coded twice (with the second coder blinded to the first result), according to the international codes for industries (ISIC-1975) and occupations (ISCO-1968). For each series, linking the information about a job episode (dates, ISIC code, ISCO code) with the matrix allowed attribution of a probability of asbestos exposure to each episode and each subject. The asbestos exposure in the two series was compared by the kappa reproducibility coefficient.

Results: The analysis concerned 425 questionnaires. There was at least one difference in the code for either activity sector (ISIC) or occupation (ISCO) in half the episodes (50.2%). The exposure status estimated by the job-exposure matrix did not change between the series for 84.7% of the subjects. The kappa coefficient was 0.64 for all questionnaires, 0.70 when the questionnaire was coded twice by the same coder, and 0.62 when coded by two different coders.

Conclusions: Despite intra- and inter-differences between coders, the coding of job episodes for the ESPACES study appears satisfactory and hence indicates that the assessment of the subjects' asbestos exposure was assessed without major distortions. This study underlines the usefulness of employing coders specifically trained for this technique.
Mortality and cancer morbidity in a cohort of Canadian petroleum workers. R.J. Lewis, A.R. Schnatter, I. Drummond, et al. 2003;60(12):918-28. PubMed · Publisher · Free full text

Abstract

Aims: To assess mortality and cancer morbidity in Canadian petroleum workers and explore exposure-response relations for specific petroleum agents.

Methods: A total of 25 292 employees hired between 1964 and 1994 were linked to the Canadian tumour registry and national mortality database. Exposure-response trends were assessed for hydrocarbon solvents/fuels, hydrocarbon lubricants, petroleum coke/spent catalyst, and hydrogen sulphide (H2S).

Results: External comparison analyses (mortality and incidence) showed deficits for all causes and all malignant neoplasms combined and were consistent with expectation for most malignant and non-malignant sites analysed. Gall bladder cancer mortality was increased among males based on four deaths, but cases had no common job assignments and the increase was focused in workers employed <10 years. Mesothelioma incidence was increased. Most exposure-specific analyses were compromised by small numbers. Statistically significant increases were observed for H2S exposure and a subgroup of accidental deaths as well as for petroleum coke/spent catalyst exposure and lung cancer. While both findings have a degree of biologic plausibility, the H2S association, which exhibited a clearer exposure-response pattern, could be subject to unmeasured confounders. Additionally, interpretation was complicated by the high correlation between hydrocarbon and H2S exposures. With regard to lung cancer, the analysis could not adequately control for smoking, was based on small numbers, and exhibited a tenuous exposure-response pattern.

Conclusion: The findings for mesothelioma suggest the need for continued attention to asbestos in the petroleum industry. The relation between accidental deaths and H2S exposure deserves closer scrutiny in similarly exposed populations. Further analyses of lung cancer are underway and will be reported separately.
Occupational exposures and lung cancer in New Caledonia. G. Menvielle, D. Luce, J. Févotte, et al. 2003;60(8):584-9. PubMed · Publisher · Free full text

Abstract

Aims: To study the associations between occupational exposures and the risk of lung cancer in New Caledonia.

Methods: All cases diagnosed between January 1993 and December 1995 (228 lung cancers) and 305 population controls were included. Detailed information on lifetime job history, smoking, and other potential risk factors was collected by interview. Occupational exposures were assessed from the questionnaires by an industrial hygienist, without knowledge of case-control status.

Results: No significant association was found with exposures related to nickel mining and refining, the main industrial activity in the territory. Among men, an excess risk of lung cancer was found for bus and truck drivers. Increased risks were also observed in men with the highest level of cumulative exposure to cleaning products and inorganic fertilisers. Exposure to field dust was associated with lung cancer risk in both sexes, and risk increased with cumulative exposure level. In some areas tremolite asbestos derived from local outcroppings was used as a whitewash. The association between exposure to field dust and lung cancer was limited to men and women exposed to this whitewash-that is, living in areas where the soil may contain tremolite.

Conclusion: This study shows several associations between occupational exposures and lung cancer. The findings suggest that exposure to tremolite fibres from cultivated fields may increase the risk of lung cancer in New Caledonia.
Update of predictions of mortality from pleural mesothelioma in the Netherlands. O. Segura, A. Burdorf, C. Looman. 2003;60(1):50-5. PubMed · Publisher · Free full text

Abstract

Aims: To predict the expected number of pleural mesothelioma deaths in the Netherlands from 2000 to 2028 and to study the effect of main uncertainties in the modelling technique.

Methods: Through an age-period-cohort modelling technique, age specific mortality rates and cohort relative risks by year of birth were calculated from the mortality of pleural mesothelioma in 1969-98. Numbers of death for both sexes were predicted for 2000 to 2028, taking into account the most likely demographic development. In a sensitivity analysis the relative deviation of the future death toll and peak death number were studied under different birth cohort risk assumptions.

Results: The age-cohort model on mortality 1969-98 among men showed the highest age specific death rates in the oldest age group (79 per 100 000 person-years in the age group 80-84 years) and the highest relative risks for the birth cohorts of 1938-42 and 1943-47. Among men a small period effect was observed. The age-cohort model was considered the best model for predicting future mortality. The most plausible scenario predicts an increase in pleural mesothelioma mortality up to 490 cases per year in men, with a total death toll close to 12 400 cases during 2000-28. However, using different assumptions this death toll could rise to nearly 15 000 in men (20% increase). Mortality among women remains low, with a total death toll of about 800 cases. It is predicted that the total death toll in the period 2000-28 is 44% lower than previous predictions using mortality data from 1969 to 1993.

Conclusion: Adding five recent years of observed mortality in an age-cohort model resulted in a 44% lower prediction of the future death toll of pleural mesothelioma. A statistically significant period effect was observed, possibly influenced by initial asbestos safety guidelines in the 1970s and introduction of the ICD-10 codification.
Asbestos fibreyears and lung cancer: a two phase case-control study with expert exposure assessment. H. Pohlabeln, P. Wild, W. Schill, et al. 2002;59(6):410-4. PubMed · Publisher · Free full text

Abstract

Aims: To assess the cumulative effect of asbestos on lung cancer risk where the exposure is assessed by an expert rating.

Methods: 1678 male cases and controls were enrolled in a population based matched case-control study, focused on occupational risk factors, carried out in West Germany. The exposure to asbestos was computed as lifelong working hours. For a validation subsample of 164 matched pairs from this study the intensity of asbestos exposure was further assessed by a panel of experts in order to obtain an estimate of the cumulative exposure on a time by intensity scale (fibreyears). The information on duration of asbestos exposure in the original study was combined with the fibreyears following the two phase case control study paradigm.

Results: The number of exposed subjects in the validation subsample was 75 cases and 71 controls. The percentage of subjects with a cumulative exposure < or =1, 1 to < or =10, and >10 fibreyears was 16%, 15%, and 15% for the cases and 18%, 16%, and 9% respectively for the controls. The smoking adjusted odds ratios for the fibreyears based on an unconditional logistic regression were 0.81, 1.02, and 1.60 respectively with increasing exposure categories (not significant). The coefficient (beta) for a log transformed trend was 1.156. Applying the two phase paradigm, these odds ratios became 0.86, 1.33, and 1.94; the latter reached significance and the beta coefficient was 1.178.

Conclusions: The two phase paradigm allowed us to obtain a more precise estimate of the effect of asbestos on lung cancer. Results are consistent with a doubling of the lung cancer risk with 25 fibreyears asbestos exposure.
Cancer at sea: a case-control study among male Finnish seafarers. H. Saarni, J. Pentti, E. Pukkala. 2002;59(9):613-9. PubMed · Publisher · Free full text

Abstract

Aims: To study the possible work related reasons for the increased incidence of many cancers among seafarers.

Methods: A case-control study, nested in a cohort of all male seafarers (n = 30 940) who, according to the files of the Seamen's Pension Fund, had worked on board Finnish ships for any time during the period 1960-80. Cases of cancer of the lung, nervous system, kidney, and pancreas, leukaemia, lymphoma, and all cases histologically defined as mesotheliomas were identified from the Finnish Cancer Registry in 1967-92. The preceding numbers of years at sea in various occupational categories were collected according to the type of ship (dry cargo ship, tanker, passenger vessel, icebreaker, other vessel).

Results: The incidence for lung cancer among engine crew increased with the increase in employment time, the odds ratio (OR) after three years being 1.68 (95% CI 1.17 to 2.41). The OR of lung cancer for deck officers was 0.42 (95% CI 0.29 to 0.61). Deck personnel on icebreakers had a significantly increased risk of lung cancer > or =20 years after first employment (OR 3.41, 95% CI 1.23 to 9.49). The OR for mesothelioma among engine crew with a latency of 20 years was 9.75 (95% CI 1.88 to 50.6). The OR for renal cancer among deck officers after three years employment was 2.15 (95% CI 1.14 to 4.08), but there was no increase by employment time or by latency. A rise of OR for lymphoma was detected among deck personnel on tankers, if the employment had lasted over three years (OR 2.78, 95% CI 0.98 to 7.92). The risk pattern for leukaemia was similar to that of lymphoma, the OR among deck personnel on tankers varying from 2.26 (95% CI 1.01 to 5.06) to 6.86 (95% CI 1.62 to 28.8) depending on the length of employment.

Conclusions: Results indicate that occupational exposures of deck crews on tankers add to their risk of renal cancer, leukaemia, and possibly lymphoma. Engine crews have an asbestos related risk of mesothelioma, and the engine room conditions also seem to increase risk of lung cancer.
Chrysotile and tremolite asbestos fibres in the lungs and parietal pleura of Corsican goats. P. Dumortier, F. Rey, J.R. Viallat, et al. 2002;59(9):643-6. PubMed · Publisher · Free full text

Abstract

Background And Aims: Environmental exposures to chrysotile and tremolite from the soil cause pleural plaques and mesothelioma in northeast Corsica. Goats grazing in the contaminated areas inhale asbestos fibres. We used this natural animal model to study whether these exposures actually result in increased fibre burdens in the lungs and parietal pleura.

Methods: Ten goats from areas with asbestos outcrops and two from other areas were slaughtered. Fibre content of lung and parietal pleural samples was determined by analytical transmission electron microscopy.

Results: Both chrysotile and tremolite fibres were detected. In the exposed goats, the geometric mean concentrations of asbestos fibres longer than 1 microm were 0.27 x 10(6) fibres/g dry lung tissue and 1.8 x 10(6) fibres/g dry pleural tissue. Asbestos fibres were not detected in the lungs of the two control goats. Chrysotile fibres shorter than 5 microm were predominant in the parietal pleura. Tremolite fibres accounted for 78% and 86% of the fibres longer than 5 microm in lung and parietal pleural samples, respectively.

Conclusions: Environmental exposure in northeast Corsica results in detectable chrysotile and tremolite fibre loads in the lung and parietal pleura of adult goats. Tremolite fibres of dimensions with a high carcinogenic potency are detected in the parietal pleura.
Joint action of smoking and asbestos exposure on lung cancer. F.D. Liddell. 2002;59(7):494-5; author reply 495-6. Comment · Letter PubMed · Publisher · Free full text

Summary

This letter commented on a 2001 review by P N Lee of how smoking and asbestos exposure act jointly on lung cancer risk, and it was published with Lee's reply. Lee had calculated V, the ratio of the asbestos relative risk in smokers to that in non-smokers, where V = 1 indicates a multiplicative interaction. His original weighted average for 16 results was 0.90 (95% CI 0.67 to 1.20). After acknowledged errors were corrected, V fell to 0.83 (95% CI 0.63 to 1.08). Values were 0.63 for cohort studies and 1.08 for case-referent studies, a difference with p = 0.049. Liddell argued for excluding four further results: two cohorts that broke the rule of independence, one showing no asbestos effect, and a Chinese cohort with low smoking risks. These exclusions gave a cohort V of 0.54 (95% CI 0.35 to 0.82) and a difference between study types with p = 0.017. He questioned the case-referent studies because of unreliable job histories, proxy reporting, impure definitions of non-smokers and exposure to other carcinogens. Further adjustments gave V = 0.47 (95% CI 0.29 to 0.75). He concluded that neither the multiplicative nor the additive hypothesis was generally satisfactory and that interaction takes several forms. Lee agreed with the corrections but found the exclusions unconvincing; with them, V for all studies was 0.79 (95% CI 0.59 to 1.05). He concluded that the asbestos relative risk may be somewhat lower in smokers, but that the data did not clearly reject the multiplicative relation.

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Mind and matter: OEM and the World Trade Center. H.M. Kipen, M. Gochfeld. 2002;59(3):145-6. Editorial PubMed · Publisher · Free full text

Summary

This editorial, written about two months after the 11 September 2001 collapse of the World Trade Center (WTC), examined the aftermath from an occupational and environmental medicine viewpoint. It reported no new data. The authors identified four exposed groups (building occupants, rescue workers, demolition workers and neighbouring residents) and three phases: evacuation, rescue and recovery, and demolition and removal. They noted that by one week after the collapse 10 000 people were working on the site without a comprehensive site safety plan, and that respirator use was haphazard. Asbestos was described as a primary toxic concern for site workers and neighbours. Asbestos fireproofing had been used in the early stages of construction. Agencies sampled asbestos with different methods, units and standards, which left the public uncertain. The authors questioned claims that short fibres or chrysotile posed minimal risk. About 9000 residents returned within two weeks to buildings contaminated by dust containing lead and asbestos, with little clear guidance on cleanup. Other concerns included smoke, odours, a possible phosgene hazard, and a "WTC cough" among firefighters. The authors judged the likelihood of persistent irritant asthma from exposures after the first few days to be low. They raised the possibility of a "WTC syndrome" of unexplained symptoms, comparable to Gulf War illnesses. They concluded that combining psychosocial factors with toxic exposure assessment and risk communication is an emerging agenda for occupational and environmental medicine.

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Mortality from non-malignant respiratory disease in the fibreglass manufacturing industry. L. Chiazze, D.K. Watkins, C. Fryar, et al. 2002;59(6):369-71. PubMed · Publisher · Free full text

Abstract

Objectives: To investigate the question of whether there is an association between workplace exposures and sociodemographic factors and mortality from non-malignant respiratory disease excluding influenza and pneumonia (NMRDxIP) among workers in a fibreglass wool manufacturing facility.

Methods: A case-control study with cases and controls derived from deaths recorded from the Kansas City plant in the Owens Corning mortality surveillance system. The cases are defined as decedents with NMRDxIP as the underlying cause of death. Matched, unadjusted odds ratios (ORs) were used to assess any association between NMRDxIP and cumulative exposure history and sociodemographic factors individually. Matched, adjusted ORs were obtained by conditional logistic regression to estimate the effect of any one variable while controlling for the effect of all the others.

Results: Results of the unadjusted analysis, considering variables one at a time, yielded no significant associations between NMRDxIP and any of the exposure or sociodemographic variables. The smoking OR was substantially increased (OR 5.09; 95%CI 0.65 to undeterimed). Also, there were no significant variables in a conditional logistic regression analysis in which all variables were simultaneously adjusted. ORs for respirable glass fibres were below unity at all concentrations of exposure in the adjusted analysis. For respirable silica there was no consistent relation across all exposure levels. The ORs increased through the first three exposure concentrations but decreased for the highest exposure. However, ORs although not significant, are greater than unity for all respirable concentrations of silica exposure.

Conclusions: The findings for Kansas City show no association between respirable glass fibres and NMRDxIP. The adjusted ORs for all exposures to respirable fibres were less than unity. On the other hand, the ORs for silica exposures were all above unity although there was no clear dose-response relation and none of the ORs were significant. Exposures for all substances considered were very low. Further, given the number of cases and controls, the statistical power to detect relatively small increases in risk, if any increase truly exited, was relatively low. The ORs for exposures to silica were all above unity although there was no clear dose-response relation and none of the ORs were significant. These raised ORs for silica suggest that continued surveillance would be prudent.
Respiratory morbidity in a population of French dental technicians. S. Radi, J.C. Dalphin, P. Manzoni, et al. 2002;59(6):398-404. PubMed · Publisher · Free full text

Abstract

Aims: To compare wage earner dental technicians with non-exposed salaried subjects for the prevalence of respiratory symptoms and function, and chest x ray abnormalities.

Methods: A total of 134 dental technicians and 131 non-exposed subjects participated. A medical and an occupational questionnaire were filled in to evaluate the prevalence of respiratory symptoms and occupational exposures. Subjects underwent respiratory tests and chest x ray examination.

Results: Mean age of the dental technicians was 36.6 years with a mean duration of dental work of 16.5 years. There was a significant risk of cough (day and night) and usual phlegm in dental technicians. Respiratory function parameters were lower in dental technicians with a significant difference between exposed and non-exposed groups for % FVC (forced vital capacity), % FEF(25) (forced mid expiratory flow), and % FEF(50). The prevalence of small opacities increased with age. Small opacities were significantly related to an exposure to asbestos in the past.

Conclusions: Our young population of dental technicians is at risk of respiratory morbidity. They should benefit from adequate technical prevention measures.
Translating evidence about occupational conditions into strategies for prevention. D.K. Verma, J.T. Purdham, H.A. Roels. 2002;59(3):205-13; quiz 214. Review PubMed · Publisher · Free full text

Summary

This educational review examined how evidence about hazardous workplace conditions has been translated into prevention strategies. The authors described control at two levels. At the societal level, control is mainly by regulation, ranging from guidelines to exposure limits to bans. At the workplace level, it includes substitution, engineering controls, personal protective equipment, education and training, and surveillance. They presented the process as three linked boxes: sources of evidence (toxicology, epidemiology, occupational medicine, occupational hygiene, unions and workers), scientific, social and economic influencing factors, and prevention strategies. Eight case studies illustrated the process: vinyl chloride, 2-naphthylamine, asbestos, silica, benzene, flour dust, noise and manganese. For asbestos, the authors described asbestosis reported in 1907 and lung cancer in the 1930s, slower acceptance by industry, and debate over the extent of risk and over fibre types, which delayed stricter control. North American standards now stood at 0.1 fibres/ml for all types, compared with an early-1970 ACGIH limit of 5 million particles per cubic foot (very roughly 30 fibres/ml). They noted the proposed European Union ban, Canadian lobbying against it, and predicted an epidemic of asbestos-related disease in developing countries where asbestos remains widely used. For vinyl chloride, first reports in 1974 were followed by controls in 1975. The authors concluded that there has usually been a very long delay between first evidence and effective control, and that little changes at workplaces without specific regulation.

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Updated epidemiological study of workers at two California petroleum refineries, 1950-95. K.P. Satin, W.J. Bailey, K.L. Newton, et al. 2002;59(4):248-56. PubMed · Publisher · Free full text

Abstract

Objectives: To further assess the potential role of occupational exposures on mortality, a second update of a cohort study of workers at two petroleum refineries in California was undertaken.

Methods: Mortality analyses were based on standardised mortality ratios (SMRs) and 95% confidence intervals (95% CIs) using the general population of California as a reference. Additional analyses of lymphatic and haematopoietic cancer deaths and diseases related to asbestos were undertaken.

Results: The update consisted of 18,512 employees, who contributed 456,425 person-years of observation between 1950 and 1995. Both overall mortality and total cancer mortality were significantly lower than expected, as were several site specific cancers and non-malignant diseases. In particular, no significant increases were reported for leukaemia cell types or non-Hodgkin's lymphoma. Mortality excess from multiple myeloma was marginally significant. The excess was confined to employees enrolled before 1949. Furthermore, there was no significant upward trend based on duration of employment, which argues against a causal interpretation relative to employment or exposures at the refineries. No increase was found for diseases related to asbestos: pulmonary fibrosis; lung cancer; or malignant mesothelioma. There was no significant increase in mortality from any other cancers or non-malignant diseases.

Conclusion: This second update provides additional reassurance that employment at these two refineries is not associated with increased risk of mortality.
A case-referent study of cancer mortality among sulfate mill workers in Sweden. E. Andersson, S. Hagberg, T. Nilsson, et al. 2001;58(5):321-4. PubMed · Publisher · Free full text

Abstract

Objectives: To investigate whether workers in Swedish sulfate mills have an increased risk of death from certain malignancies that have previously been linked to the pulping process.

Methods: Subjects of the study (n=2480) were men aged 40-75 at death during 1960-89 in the parishes surrounding four sulfate mills. Exposure assessment was based on information from the personnel files in the mills- 35% of the subjects were recognised there, and work categories were created.

Results: Among all sulfate mill workers, the odds ratio (OR) (90% confidence interval (90% CI)) for death from lung cancer was 1.6 (1.1 to 2.3), pleural mesotheliomas 9.5 (1.9 to 48), brain tumours 2.6 (1.2 to 5.3), and liver or biliary tract cancer 2.3 (1.0 to 5.2). There was an increased mortality from leukaemia among workers in the soda recovery plant (5.9 (2.6 to 13)) and bleaching plant and digester house (2.8 (1.0 to 7.5)).

Conclusions: Sulfate mill workers were at increased risk of dying from lung cancer and pleural mesotheliomas, probably due to exposure to asbestos. Increased risks of brain tumours and cancers of the liver or biliary tract were also found but the aetiology is not obvious.
An epidemiological study of the respiratory health of workers in the European refractory ceramic fibre industry. H.A. Cowie, P. Wild, J. Beck, et al. 2001;58(12):800-10. PubMed · Publisher · Free full text

Abstract

Objectives: To investigate possible relations between respiratory health and past airborne exposure to refractory ceramic fibres (RCFs) and respirable dust in workers at six European factories, studied previously in 1987.

Methods: The target population comprised all current workers associated with RCF production, plus others who had participated in 1987 "leavers". Information was collected on personal characteristics, chest radiographs, lung function, respiratory symptoms, smoking, and full occupational history. Regression analysis was used to study relations between indices of health of individual workers and of cumulative exposure to airborne dust and fibres, and likely past exposure to asbestos.

Results And Discussion: 774 workers participated (90% of current workers, 37% of leavers). Profusion of small opacities in exposed workers (51% 0/1+; 8% 1/0+) was similar to that among an unexposed control group but higher than in new readings of the 1987 study films (11% 0/1+, 2% 1/0+). The large difference between 1987 and recent films may be, at least in part, a reading artefact associated with film appearance. Small opacities of International Labour Organisation (ILO) category 1/0+ were not associated with exposure. An association of borderline significance overall between 0/1+ opacities and exposure to respirable fibres was found for some exposure periods only, the time related pattern being biologically implausible. Pleural changes were related to age and exposure to asbestos, and findings were consistent with an effect of time since first exposure to RCFs. Among men, forced expired volume in 1 second (FEV(1)) and forced vital capacity (FVC) were inversely related to exposure to fibres, in current smokers only. FEV(1)/ FVC ratio and transfer factor (TL(CO)) were not related to exposures. The estimated restrictive effect was on average mild. Prevalence of respiratory symptoms was low. Chronic bronchitis and its associated symptoms (cough, phlegm) showed some association with recent exposure to respirable fibres. This could be due to an irritant effect of RCFs.
Erionite bodies and fibres in bronchoalveolar lavage fluid (BALF) of residents from Tuzköy, Cappadocia, Turkey. P. Dumortier, L. Coplü, I. Broucke, et al. 2001;58(4):261-6. PubMed · Publisher · Free full text

Abstract

Objectives: The high incidence of malignant mesothelioma in some villages of Cappadocia (Turkey) is due to environmental exposure to erionite fibres. The aim was to evaluate the fibre burden in bronchoalveolar lavage fluid (BALF) from inhabitants of an erionite village and compare it with Turkish subjects with or without environmental exposure to tremolite asbestos.

Methods: Ferruginous bodies (FBs) and fibres were measured and analyzed by light and transmission electron microscopy (TEM) in the BALF of 16 subjects originating from Tuzköy.

Results: FBs were detected in the BALF of 12 subjects, with concentrations above 1 FB/ml in seven of them. Erionite was the central fibre of 95.7% of FBs. Erionite fibres were found in the BALF of all subjects, by TEM, and these fibres were low in Mg, K, and Ca compared with erionite from Tuzköy soil. The mean concentration of erionite fibres in BALF was similar to that of tremolite fibres in Turks with environmental exposure to tremolite. The proportion of fibres longer than 8 microm in BALF represented 35.6% for erionite compared with 14.0% for tremolite. The asbestos fibre concentrations in erionite villagers was not different from that in Turks without environmental exposure to tremolite.

Conclusion: Analysis of BALF gives information about fibre retention in populations environmentally exposed to erionite for whom data on fibre burden from lung tissue samples are scarce. This may apply to exposed Turks having emigrated to other countries.
Exposure to tremolite asbestos and respiratory health in Swedish dolomite workers. A.I. Seldén, N.P. Berg, E.A. Lundgren, et al. 2001;58(10):670-7. PubMed · Publisher · Free full text

Abstract

Objectives: Deposits of carbonate rock like limestone and dolomite may contain tremolite asbestos. This study assessed the exposure to tremolite asbestos and the respiratory health of Swedish dolomite workers.

Methods: 95% of 137 eligible workers at two dolomite producing companies completed a self administered questionnaire that included questions on respiratory symptoms and were examined with spirometry as well as chest radiography. Total exposure to dust was gravimetrically measured and the tremolite asbestos content of the dust was assessed with polarisation and phase contrast microscopy.

Results: Dolomite dust concentrations were moderate (median 2.8 mg/m3) and tremolite asbestos concentrations were generally below the limit of detection (<0.03 fibres/ml). Somewhat higher values, around 0.1 fibres/ml, were obtained in manual stone sorting and bagging. Respiratory symptoms suggestive of chronic bronchitis were more related to smoking than to estimates of individual exposure to dust. The mean vital capacity was 0.2 l lower than expected after adjustment for sex, age, height, and smoking but the decline in lung function was not associated with current or cumulative exposure to dust in a clear cut way. Two definite cases of pleural plaques and one possible case of simple pneumoconiosis were noted, but the plaques could not be attributed exclusively to exposure to tremolite asbestos.

Conclusions: Dolomite mining and milling may indeed entail low levels of exposure to tremolite asbestos, but this exposure was not a strong determinant of respiratory symptoms, lung function, or pneumoconiosis in exposed Swedish workers. This was true also for dolomite dust. The hazards of exposure to tremolite asbestos may vary across deposits, however, and additional studies at other sites of carbonate rock exploitation are warranted.
Relation between exposure to asbestos and smoking jointly and the risk of lung cancer. P.N. Lee. 2001;58(3):145-53. Review PubMed · Publisher · Free full text

Abstract

Objectives: To review evidence about the joint relation of exposure to asbestos and smoking on the risk of lung cancer to answer three questions: (1) does asbestos increase risk in non-smokers; (2) are the data consistent with an additive model; and (3) are the data consistent with a multiplicative model?

Methods: Analysis of 23 studies reporting epidemiological evidence on the joint relation. Comparison of risk of lung cancer in subjects unexposed to asbestos or smoking, exposed to asbestos only, to smoking only, or to both. Estimation of the relative risk associated with asbestos exposure in non-smokers and of statistics testing for additivity and multiplicativity of risk.

Results: Eight of the 23 studies provided insufficient data on the risk of lung cancer in non-smokers to test for possible effects of asbestos. Asbestos exposure was associated with a significantly (p<0.05) increased risk in non-smokers in six of the remaining studies and with a moderately increased, but not significant, increase in a further six. In two of the three studies that found no increase, asbestos exposure was insufficient to increase risks in smokers. In 30 of 31 data sets analysed, risk in the combined exposure group was greater than predicted by the additive model. There was no overall departure from the multiplicative model, the proportional increase in risk of lung cancer with exposure to asbestos being estimated as 0.90 (95% confidence interval (95% CI) 0.67 to 1.20) times higher in smokers than non-smokers. For two studies significant (p<0.05) departures from a multiplicative relation were found in some, but not all, analyses. Reasons are presented why these may not indicate true model discrepancies.

Conclusions: Asbestos exposure multiplies risk of lung cancer by a similar factor in non-smokers and smokers. The extent to which it multiplies risk varies between studies, no doubt depending on the type of asbestos involved, and the nature, extent, and duration of exposure.
Small area estimation of incidence of cancer around a known source of exposure with fine resolution data. E. Kokki, J. Ranta, A. Penttinen, et al. 2001;58(5):315-20. PubMed · Publisher · Free full text

Abstract

Objectives: To describe the small area system developed in Finland. To illustrate the use of the system with analyses of incidence of lung cancer around an asbestos mine. To compare the performance of different spatial statistical models when applied to sparse data.

Methods: In the small area system, cancer and population data are available by sex, age, and socioeconomic status in adjacent "pixels", squares of size 0.5 km x 0.5 km. The study area was partitioned into sub-areas based on estimated exposure. The original data at the pixel level were used in a spatial random field model. For comparison, standardised incidence ratios were estimated, and full bayesian and empirical bayesian models were fitted to aggregated data. Incidence of lung cancer around a former asbestos mine was used as an illustration.

Results: The spatial random field model, which has been used in former small area studies, did not converge with present fine resolution data. The number of neighbouring pixels used in smoothing had to be enlarged, and informative distributions for hyperparameters were used to stabilise the unobserved random field. The ordered spatial random field model gave lower estimates than the Poisson model. When one of the three effects of area were fixed, the model gave similar estimates with a narrower interval than the Poisson model.

Conclusions: The use of fine resolution data and socioeconomic status as a means of controlling for confounding related to lifestyle is useful when estimating risk of cancer around point sources. However, better statistical methods are needed for spatial modelling of fine resolution data.
Asbestosis and lobar site of lung cancer. W. Weiss. 2000;57(5):358-60. Review PubMed · Publisher · Free full text

Abstract

Objective: To assess the evidence for the hypothesis that lung cancer has a predilection for the lower lobes in workers with asbestosis.

Method: A review of the available literature with relevant information.

Results: Six published reports were analysed. In four studies limited to series of cases with diagnoses of asbestosis, three showed lower lobe predominance of lung cancer whereas the fourth study included cases in which the radiographic readings did not meet the usual criterion of profusion for asbestosis. One cohort study showed lower lobe predominance; the other reported only 33% lower lobe cancers compared with 20% in unexposed controls.

Conclusion: There is some support for the hypothesis but more studies are needed.
Future trends in mortality of French men from mesothelioma. A. Banaei, B. Auvert, M. Goldberg, et al. 2000;57(7):488-94. PubMed · Publisher · Free full text

Abstract

Objectives: Previous projections of mortality from mesothelioma among French men have used the age-generation method, based on the Poisson regression model. In this study an alternative method to model mortality from mesothelioma was used to predict its future trend: this method was based on the risk function that links this mortality to past exposure to asbestos, combined with population exposure data.

Method: Data on past French asbestos imports were used to model the overall past exposure to asbestos in men and assess two extreme scenarios (optimistic and pessimistic) for its future trends. The number of male deaths occurring between the ages of 50 and 79, from 1997-2050, was then calculated with the risk function for mesothelioma.

Results: The results showed that mortality from mesothelioma among French men aged 50-79 will continue to increase, reaching a peak averaging between 1140 (optimistic scenario) and 1300 deaths (pessimistic scenario) annually around the years 2030 and 2040, respectively. No preventive measures applied now will affect this trend before then. These results are similar to those of two other predictions of mortality from mesothelioma among French men: a peak around 2030 of 800-1600 deaths annually among men aged 25-89 years, and a peak around 2020 of 1550 deaths annually among men aged 40-84.

Conclusions: Our results indicate that between 1997 and 2050, the most optimistic and pessimistic trends of future exposure will lead to the deaths from mesothelioma of between 44 480 and 57 020 men, with a corresponding loss of from 877 200 to 1 171 500 person-years of life.
Mortality from all cancers of asbestos factory workers in east London 1933-80. G. Berry, M.L. Newhouse, J.C. Wagner. 2000;57(11):782-5. PubMed · Publisher · Free full text

Abstract

Objective: To give the observed and expected deaths due to cancer at all separate sites in asbestos workers in east London, and to analyse these for overall effect and exposure-response trend.

Methods: The mortality experience of a cohort of over 5000 men and women followed up for over 30 years since first exposure to asbestos has been extracted.

Results: There was a large excess of deaths due to cancer (537 observed, 222 expected). Most of these were due to cancer of the lung (232 observed, 77 expected) and pleural (52) and peritoneal (48) mesothelioma. The exposure-response trend for all these three causes was highly significant. There was also an excess of cancer of the colon (27 observed, 15 expected) which was significantly related to exposure. There were significant excesses of cancer of the ovary, of the liver, and of the oesophagus but with no consistent relation to exposure.

Conclusions: The excess risk of cancer after exposure to asbestos was mainly due to cancer of the lung and mesothelioma. An exposure related excess of cancer of the colon was also detected but the possibility that some of these deaths may have been peritoneal mesotheliomas could not be excluded. There was no consistent evidence of exposure related excesses at any other site.
Occupational exposures and pancreatic cancer: a meta-analysis. I.A. Ojajärvi, T.J. Partanen, A. Ahlbom, et al. 2000;57(5):316-24. Meta-analysis PubMed · Publisher · Free full text

Abstract

Objectives: Consolidation of epidemiological data on pancreatic cancer and worksite exposures.

Methods: Publications during 1969-98 were surveyed. Studies without verified exposures were excluded. Meta-analyses were conducted on data from 92 studies covering 161 populations, with results for 23 agents or groups of agents. With a standard format, five epidemiologists extracted risk estimates and variables of the structure and quality of each study. The extracted data were centrally checked. Random meta-models were applied.

Results: Based on 20 populations, exposure to chlorinated hydrocarbon (CHC) solvents and related compounds was associated with a meta-risk ratio (MRR) of 1.4 (95% confidence interval (95% CI) 1.0 to 1.8). Nickel and nickel compounds were considered in four populations (1.9; 1.2 to 3.2). Excesses were found also for chromium and chromium compounds (1.4; 0.9 to 2.3), polycyclic aromatic hydrocarbons (PAHs) (1.5; 0.9 to 2.5), organochlorine insecticides (1.5; 0.6 to 3.7), silica dust (1.4; 0.9 to 2.0), and aliphatic and alicyclic hydrocarbon solvents (1.3; 0.8 to 2.8). Evidence on pancreatic carcinogenicity was weak or non-positive for the following agents: acrylonitrile (1.1; 0.0 to 6.2); arsenic (1.0; 0.6 to 1.5); asbestos (1.1; 0.9 to 1.5); diesel engine exhaust (1.0; 0.9 to 1.3); electromagnetic fields (1.1; 0.8 to 1.4); formaldehyde (0. 8; 0.5 to 1.0); flour dust (1.1; 0.3 to 3.2); cadmium and cadmium compounds (0.7; 0.4 to 1.4); gasoline (1.0; 0.8 to 1.2); herbicides (1.0; 0.8 to 1.3); iron and iron compounds (1.3; 0.7 to 2.5); lead and lead compounds (1.1; 0.8 to 1.5); man-made vitreous fibres (1.0; 0.6 to 1.6); oil mist (0.9; 0.8 to 1.0); and wood dust (1.1; 0.9 to 2.5). The occupational aetiological fraction of pancreatic cancer was estimated at 12%. In a subpopulation exposed to CHC solvents and related compounds, it was 29%; to chromium and chromium compounds, 23%; to nickel and nickel compounds, 47%; to insecticides, 33%; and to PAHs, 33%.

Conclusion: Occupational exposures may increase risk of pancreatic cancer. High quality studies are called for on interactions between occupational, environmental, and lifestyle factors as well as interactions between genes and the environment.
Risk of mesothelioma from exposure to crocidolite asbestos: a 1995 update of a South African mortality study. D. Kielkowski, G. Nelson, D. Rees. 2000;57(8):563-7. PubMed · Publisher · Free full text

Abstract

Objective: To find the risk of developing mesothelioma in a cohort born in 1916-36 in Prieska, Northern Cape Province, South Africa.

Methods: A birth cohort mortality study was carried out in a small town in the Northern Cape Province, South Africa, with a history of crocidolite asbestos mining and milling. The cohort comprised all white births registered in the magisterial district of Prieska from 1916 to 1936, inclusive (2390). Causes of death due to mesothelioma and other cancers as recorded on medical certificates of cause of death were investigated. Person-years analysis was used to calculate mortalities due to mesothelioma, other respiratory cancers, and other non-respiratory cancers. Proportional cancer mortalities were also calculated for mesothelioma and other specific neoplasms.

Results: The follow up rate for the cohort was 74.3% in 1995, and 683 traced members (38.6%) had died. Cause of death was unknown for 6.4% of deaths. There were 118 cases of cancer, 28 of them from mesothelioma, giving a cause specific mortality for mesothelioma of 277 (170-384) per 10(6) person-years. The rates for men and women were 366 and 172 per 10(6) person-years, respectively. The mortality for lung cancer (29 deaths) was 287 (135-436) per 10(6) person-years, and that for other non-respiratory cancers (60 deaths) was 593 (442-745). Two cases of laryngeal and four of colon cancer were observed. All cancer mortality, mesothelioma, and lung cancer proportional cancer mortality ratios were increased.

Conclusion: The mortality for mesothelioma in men was twice that in women, probably because men were more likely to have had both occupational and environmental exposure to asbestos. Nevertheless, the mortality in women was still high and is probably indicative of the environmental exposure as white women were rarely employed in the asbestos industry in the Prieska area. Due to the long latency from first exposure to diagnosis of the neoplasm, the cause specific mortality in this cohort could be expected to increase rapidly over the next 10 years.
Update of the Texaco mortality study 1947-93: Part II. M.M. Finkelstein. 2000;57(2):143-4. Comment · Letter PubMed · Publisher · Free full text
Updated mortality among diverse operating segments of a petroleum company. R.J. Lewis, A.R. Schnatter, A.M. Katz, et al. 2000;57(9):595-604. PubMed · Publisher · Free full text

Abstract

Objectives: To update mortality for 34 560 employees from diverse operating segments of a Canadian petroleum company; and to investigate potential relations with occupational factors.

Methods: Employees from 1964-83 were linked to the Canadian mortality data base to provide 11 years additional follow up. There were 6760 deaths and 750 683 person-years of follow up compared with 3909 and 428 190, respectively, in the earlier study. Analyses used standardised mortality ratios (SMRs) to compare worker cause specific mortality with the Canadian general population. Duration of employment and latency analyses were performed for causes previously found to be increased in this and other petroleum cohorts, as well as any findings of interest.

Results: For the period 1964-94, employees experienced significantly low overall mortality (SMR=0.86 men, SMR=0.80 women). Kidney cancer, which has been increased in some studies of petroleum workers, was not increased. Acute non-lymphocytic leukaemia in exposed operating segments was consistent with the expected or only slightly, non-significantly increased. The most notable finding was increased deaths from mesothelioma among refinery and petrochemical workers (SMR 8.68; 95% confidence interval (95% CI) 5.51 to 13.03), most of whom were long term employees in jobs with presumed exposure to asbestos (mechanical and pipefitters). Deaths from multiple myeloma among marketing and distribution workers, which were previously increased, remained increased (SMR 2.08; 95% CI 0.95 to 3.95) in the update period 1984-94; however, there was no clear pattern by duration of employment or latency. Aortic aneurysms, which also were previously significantly increased among marketing and distribution workers approached the expected in the update period (SMR 1.18; 95% CI 0. 65-1.98). Analyses by duration of employment showed suggestive trends for aortic aneurysms, but earlier studies of this cohort have not found a relation between aortic aneurysms and exposure to hydrocarbons.

Conclusion: The additional 2851 deaths and 322 493 person-years of follow up strengthened the assessment of mortality patterns relative to occupational factors. With the exception of mesothelioma, no clear work related increases in disease were identified.
Workplace exposures and oesophageal cancer. M.E. Parent, J. Siemiatycki, L. Fritschi. 2000;57(5):325-34. PubMed · Publisher · Free full text

Abstract

Objectives: To describe the relation between oesophageal cancer and many occupational circumstances with data from a population based case-control study.

Methods: Cases were 99 histologically confirmed incident cases of cancer of the oesophagus, 63 of which were squamous cell carcinomas. Various control groups were available; for the present analysis a group was used that comprised 533 population controls and 533 patients with other types of cancer. Detailed job histories were elicited from all subjects and were translated by a team of chemists and hygienists for evidence of exposure to 294 occupational agents. Based on preliminary results and a review of literature, a set of 35 occupational agents and 19 occupations and industry titles were selected for this analysis. Logistic regression analyses were adjusted for age, birthplace, education, respondent (self or proxy), smoking, alcohol, and beta-carotene intake.

Results: Sulphuric acid and carbon black showed the strongest evidence of an association with oesophageal cancer, particularly squamous cell carcinoma. Other substances showed excess risks, but the evidence was more equivocal-namely chrysotile asbestos, alumina, mineral spirits, toluene, synthetic adhesives, other paints and varnishes, iron compounds, and mild steel dust. There was considerable overlap in occupational exposure patterns and results for some of these substances may be mutually confounded. None of the occupations or industry titles showed a clear excess risk; the strongest hints were for warehouse workers, food services workers, and workers from the miscellaneous food industry.

Conclusions: The data provide some support for an association between oesophageal cancer and a handful of occupational exposures, particularly sulphuric acid and carbon black. Many of the associations found have never been examined before and warrant further investigation.

1990s

Asbestosis and small cell lung cancer in a clutch refabricator. J.L. Levin, M.F. O'Sullivan, C.J. Corn, et al. 1999;56(9):602-5. Case report PubMed · Publisher · Free full text

Abstract

Objectives: To present a case of asbestosis and small cell lung cancer caused by asbestos in a clutch refabricator.

Methods: Exposed surfaces of used clutches similar to those refabricated in the worker's workplace were rinsed, and the filtrate analysed by analytical transmission electron microscopy. Tissue samples were also analysed by this technique.

Results: Numerous chrysotile fibres of respirable dimensions and sufficient length to form ferruginous bodies (FBs) were detected from rinsed filtrates of the clutch. Bronchoalveolar lavage fluid contained many FBs, characteristic of asbestos bodies. Necropsy lung tissue showed grade 4 asbestosis and a small cell carcinoma in the right pulmonary hilum. Tissue analysis by light and analytical electron microscopy showed tissue burdens of coated and uncoated asbestos fibres greatly exceeding reported environmental concentrations (3810 FBs/g dry weight and 2,080,000 structures > or = 0.5 micron/g dry weight respectively). 72% Of the cores were identified as chrysotile.

Conclusions: Clutch refabrication may lead to exposure to asbestos of sufficient magnitude to cause asbestosis and lung cancer.
Chemical differences between long and short amosite asbestos: differences in oxidation state and coordination sites of iron, detected by infrared spectroscopy. A. Graham, J. Higinbotham, D. Allan, et al. 1999;56(9):606-11. PubMed · Publisher · Free full text

Abstract

Objectives: Short fibres of amosite asbestos (SFA), obtained by ball milling of long fibres (LFA), have been shown to be less pathogenic than long fibres. Accumulating evidence suggests an important role for differences in surface chemistry between fibres. Iron has been implicated in the pathogenesis of asbestos fibres. In this study infrared (IR) spectroscopy was used to compare LFA and SFA in terms of the coordination and oxidation state of iron at the three cation sites (M1, M3, M1).

Methods: Infrared was used to examine LFA ad SFA, when dry and when hydrated in the presence and absence of the chelators desferroxamine and ferrozine. With appropriate software the proportions of iron and its oxidation states in the overlapping peaks were resolved and assigned, and the three coordination sites were identified. Data were obtained from 10 samples of both lengths of fibre for each of the four treatments. Iron release was also monitored.

Results: Iron was significantly more oxidised in LFA than SFA. Further oxidation of the dry fibres with water, ferrozine, or desferroxamine tended to abolish these differences. There were also significant differences between the proportions of iron held in the different coordination sites of the fibres. For LFA, a higher proportion of its iron was held in the cation sites coordinating less with iron and more with Mg. Interestingly, the sites coordinating single irons were significantly more oxidised than multiple sites. The single iron sites were more oxidised in LFA than SFA and were more readily oxidised by the treatments.

Conclusions: Important chemical differences between LFA and SFA were found. There seemed to be some mobility of iron near the surface. Based on these data it is speculated that the 1 iron surface site may be important in pathogenesis.
Clearance of man made mineral fibres from the lungs of sheep. A. Dufresne, G. Perrault, H. Yamato, et al. 1999;56(10):684-90. PubMed · Publisher · Free full text

Abstract

Objectives: To compare the clearance rate, the related pathology, and the chemical and morphological changes of three man made mineral fibres (MMMFs) in the sheep model of pneumoconiosis.

Methods: Fibrous particles were extracted from lung parenchyma and analysed by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS).

Results: The concentration of MMMF11, MMMF21, refractory ceramic fibre (RCF-1), and crocidolite asbestos fibres decreased with time according to a slow and a fast kinetic component. There was a statistical difference in the four regression lines as a function of time and the type of fibres (p < 0.001). The diameter of MMMFs decreased during the course of the time, whereas the crocidolite fibres did not seem to show any change. There was a statistical difference in the four regression lines as a function of time (p = 0.037) and type of fibres (p < 0.001). Ferruginous bodies were counted in the 40 sheep for which the latency period was 2 years. No typical ferruginous bodies were found in the groups exposed to MMMFs. The geometric mean concentration of asbestos bodies in the group exposed to crocidolite was 2421 bodies/g lung tissue (95% CI 385 to 15260).

Conclusions: The number of initially retained fibres decreased with time according to a slow and a fast kinetic component. MMMF11 and MMMF21 have similar clearance, faster than RCF-1 and crocidolite. The geometric mean diameter and length of MMMF decreased with time, but crocidolite did not. After 2 years in the sheep tracheal lobe, ferruginous bodies were not found in all three MMMF groups but were substantial in the crocidolite group. Clearance is thought to proceed through dissolution and macrophage translocation.
Flow cytometry in the exploration of the physiopathology of occupational lung disease. A.D. Curran. 1999;56(11):742-6. PubMed · Publisher · Free full text

Abstract

Flow cytometry is a simple analytical technique used for the investigation of cells taken from various sources. Cells are identified by both their physical characteristics and the presence or absence of specific molecules on the cell surface. These molecules may be either phenotypic, or induced by a specific stimulus. Flow cytometry has been used to identify the nature and extent of the immune response in several occupational respiratory conditions including occupational asthma, irritant induced respiratory problems, and asbestos related lung disease. Also, it may be of value in monitoring workplace exposure to some hazardous materials. Although of limited diagnostic value at present, the technique has provided an insight into the modulation of immune cells, and their function, in people exposed to hazardous materials in the workplace. In this review, the principals of flow cytometry will be explored and the use of flow cytometry to investigate occupational respiratory disease will be discussed.
Historical cohort study of a New Zealand foundry and heavy engineering plant. H.M. Firth, J.M. Elwood, B. Cox, et al. 1999;56(2):134-8. PubMed · Publisher · Free full text

Abstract

Objectives: To investigate the mortality of workers who had been exposed to asbestos, machining fluids and foundry work in a foundry and heavy engineering plant in the railway rolling stock manufacturing industry in New Zealand.

Methods: Historical cohort study design.

Results: For the total workforce of 3522 men employed between 1945 and 1991, follow up was 90% of person-years to 31 December 1991. Significantly increased standardised mortality ratios (SMRs) were found for all causes of death combined (SMR 1.07; 95% confidence interval (95% CI) 1.01 to 1.14), all malignancies (SMR 1.15; 95% CI 1.01 to 1.31), circulatory (SMR 1.16; 95% CI 1.07 to 1.27) and musculoskeletal diseases (SMR 3.06; 95% CI 1.39 to 5.84), all digestive cancers (SMR 1.29; 95% CI 1.04 to 1.59), all respiratory cancers (SMR 1.34; 95% CI 1.08 to 1.65), cancer of the oesophagus (SMR 1.97; 95% CI 1.01 to 3.45), and mesothelioma of the pleura (SMR 6.58; 95% CI 1.24 to 19.49). Three deaths from pleural mesothelioma were recorded, with latency times of 51, 53, and 57 years. There were no dose-response relations between exposure to asbestos, machining fluids or foundry work, or by duration of employment in the plant, and any cause of death.

Conclusions: This study found small increases in risk for several causes of death among foundry and heavy engineering workers; however, these increases were small and the possible effects of smoking and other lifestyle factors could not be excluded. There was evidence of asbestos related disease in those involved in engineering work in the past.
Increased serum concentrations of growth factor receptors and Neu in workers previously exposed to asbestos. N. Lahat, P. Froom, E. Kristal-Boneh, et al. 1999;56(2):114-7. PubMed · Publisher · Free full text

Abstract

Objectives: Epidermal growth factor receptor (EGFR) and oncogene Neu belong to a family of growth factor receptors which may play a part in carcinogenesis. Although increased serum concentrations of Neu and EGFR have been shown in several patients with asbestosis who later developed cancer, serum concentrations have not been studied in workers exposed in the past to asbestos but without asbestos related diseases.

Methods: Serum concentrations of secreted growth factor receptors were studied in 300 workers exposed in the past to asbestos and the results were compared with those of 70 controls.

Results: In the controls 4.3% (3/70) had EGFR values > 912 units/ml, compared with 39% (117/299) of the exposed group (p < 0.001). The difference in high values was even more pronounced for Neu with 4.3% of controls having Neu values > 2580 fmol/ml compared with 72% (216/299) of the exposed workers (p < 0.001). Pleural plaques predicted lower serum concentrations of EGFR but not lower Neu concentrations, and this finding remained significant after adjustment for age, exposure time, smoking, and time from initial exposure.

Conclusions: Enhanced secretion of EGFR and Neu was found in a large cohort of retired asbestos workers with a wide range of exposure and latency periods. They did not have asbestosis or cancer and their EGFR values were higher in those without plaques. Further studies are needed to confirm our results, to determine the source of the secreted growth factor receptors, and to study their possible value as risk factors in the development of cancer.
Mesothelioma: cases associated with non-occupational and low dose exposures. G. Hillerdal. 1999;56(8):505-13. Review PubMed · Publisher · Free full text

Abstract

Objectives: To estimate the importance of low dose exposure to asbestos on the risk of mesothelioma.

Methods: A review of the literature.

Results And Conclusions: There is no evidence of a threshold level below which there is no risk of mesothelioma. Low level exposure more often than not contains peak concentrations which can be very high for short periods. There might exist a background level of mesothelioma occurring in the absence of exposure ot asbestos, but there is no proof of this and this "natural level" is probably much lower than the 1-2/million/year which has been often cited.
Mineral fibre analysis and routes of exposure to asbestos in the development of mesothelioma in an English region. D. Howel, A. Gibbs, L. Arblaster, et al. 1999;56(1):51-8. PubMed · Publisher · Free full text

Abstract

Objectives: To compare the concentrations of inorganic fibres in the lungs in cases of mesothelioma and controls: to determine whether concentrations of retained asbestos fibres differ with the different exposures identified from interview; and to investigate the existence of a cut off point in concentrations of asbestos fibres that indicates occupational exposure.

Methods: Case-control study; 147 confirmed cases of mesothelioma and 122 controls identified from deaths occurring in four districts of Yorkshire between 1979 and 1991. Surviving relatives were interviewed to determine lifetime exposure history to asbestos. Mineral fibre analysis was carried out on lung tissue from postmortem examinations.

Results: Odds on high concentrations of retained asbestos fibres were greater in cases than controls. After excluding subjects with occupational and paraoccupational exposure, the odds on high concentrations were still greater in cases than controls, but only significantly so for amphiboles. There was only a weak relation between probability of occupational exposure to asbestos and concentrations of retained asbestos fibres, and no significant difference in fibre concentrations was found between subjects who had been exposed to asbestos through different routes: these comparisons were only based on small groups. There was considerable overlap in concentrations of retained asbestos fibres between cases and controls with and without histories of occupational exposure.

Conclusions: The study has confirmed previous results of higher concentrations of asbestos fibres in cases than controls, and has shown that this is still found in subjects with little evidence of occupational and para-occupational exposure. The overlap in concentrations of retained asbestos for different groups of subjects did not suggest a clear cut of value.
Pleural mesothelioma in Sweden: an analysis of the incidence according to the use of asbestos. B. Järvholm, A. Englund, M. Albin. 1999;56(2):110-3. PubMed · Publisher · Free full text

Abstract

Objective: To investigate if the preventive measures taken to reduce the occupational exposure to asbestos have resulted in a decreased incidence of pleural mesothelioma in Sweden.

Methods: The incidence of pleural mesothelioma between 1958 and 1995 for birth cohorts born between 1885 and 1964 was investigated. The cases of pleural mesothelioma were identified through the Swedish Cancer Register.

Results: In 1995, around 80 cases of pleural mesothelioma could be attributed to occupational exposure to asbestos. There is an increasing incidence in more recent birth cohorts in men. The incidence was considerably higher in the male cohort born between 1935 and 1944 than in men born earlier.

Conclusions: The annual incidence of pleural mesothelioma attributable to occupational exposure to asbestos is today larger than all fatal occupational accidents in Sweden. The first asbestos regulation was adopted in 1964 and in the mid 1970s imports of raw asbestos decreased drastically. Yet there is no obvious indication that the preventive measures have decreased the risk of pleural mesothelioma. The long latency indicates that the effects of preventive measures in the 1970s could first be evaluated around 2005.
Risk of stomach cancer associated with 12 workplace hazards: analysis of death certificates from 24 states of the United States with the aid of job exposure matrices. P. Cocco, M.H. Ward, M. Dosemeci. 1999;56(11):781-7. PubMed · Publisher · Free full text

Abstract

Objective: To investigate the risk of gastric cancer associated with 12 workplace exposures suspected or discussed as aetiological agents in previous reports.

Methods: A case-control study was conducted based on the death certificates of several million deaths in 24 states of the United States in 1984-96. Overall, the data base included 41,957 deaths from stomach cancer among subjects aged > or = 25 years. These were 20,878 white men, 14,125 white women, 4215 African American men, and 2739 African American women. Two controls for each case were selected from among subjects who died from non-malignant diseases, frequency matched to cases by geographic region, race, sex and 5 year age group. Each three digit occupation and industry code listed in the 1980 United States census was classified for probability and intensity of exposure to asbestos, inorganic dust, metals, lead, polycyclic aromatic hydrocarbons (PAHs), nitrogen oxides, nitrosamines, sulphuric acid, fertilisers, herbicides, other pesticides (including insecticides and fungicides), and wood dust. These job exposure matrices were subsequently applied to the occupation-industry combinations in the death certificates of study subjects, separately by sex and race.

Results: Risk of stomach cancer showed a modest association with occupational exposure to inorganic dust (odds ratio (OR) = 1.06; 95% confidence interval (95% CI) 1.03 to 1.11) with significant increasing trends by probability and intensity of exposure overall and by cross classification of the two exposure matrices. Workplace exposure to nitrosamines also showed a modest association (OR = 1.06; 95% CI 1.01 to 1.11), but the excess risk was even smaller after adjusting for inorganic dust exposure. Risk of gastric cancer was not associated with any of the other workplace exposures considered in this study.

Conclusions: Non-differential misclassification of exposure may have caused negative findings in this study, and inorganic dust may be a partial surrogate for exposure to other unknown risk factors. Alternatively, our results suggest that occupational factors contribute little to the aetiology of gastric cancer. Inorganic dust might act through non-specific mechanisms, similar to those proposed for salt, aspirin, and heat by other authors.
Update of the Texaco mortality study 1947-93: Part II. Analyses of specific causes of death for white men employed in refining, research, and petrochemicals. B.J. Divine, C.M. Hartman, J.K. Wendt. 1999;56(3):174-80. PubMed · Publisher · Free full text

Abstract

Objective: To examine patterns of mortality for specific causes of death with increases in the Texaco mortality study to determine if the patterns are related to employment in the petroleum industry.

Methods: Mortality patterns by duration of employment in various job groups were examined for mesothelioma, non-Hodgkin's lymphoma, multiple myeloma, cell type specific leukaemia, and brain tumours.

Results: Mortality from mesothelioma was examined for the total cohort and for two maintenance groups with the greatest potential for exposure to asbestos. The insulator group had a standardised mortality ratio (SMR) of 3029, and a larger group consisting of insulators, carpenters, labourers, electricians, pipefitters, boiler-makers, and welders had an SMR of 411. The mortalities from mesothelioma increased with increasing duration of employment. Mortality was lower for those first employed after 1950. An analysis of all brain tumours for the total cohort and some job and unit subgroups resulted in an SMR of 178 for those employed on the units related to motor oil and 166 for those employed as laboratory workers. Mortality from brain tumours in both of these job groups was higher for those employed > or = 5 years in the group. An analysis of non-Hodgkin's lymphoma showed no consistent patterns among the various employment groups. Mortality from multiple myeloma was non-significantly increased among people employed on the crude (SMR = 155) and fluid catalytic cracking units (SMR = 198). Leukaemia mortality was not increased for the total cohort, and a cell type analysis of leukaemia mortality for the total cohort showed no significant increases for the major cell types. However, there were significant increases for acute unspecified leukaemia (SMR = 276) and leukaemia of unknown cell type (SMR = 231).

Conclusions: Analyses of specific causes of death by duration of employment in various job and process units did not show any patterns which suggest that, other than for mesothelioma, any of these increases in mortalities were likely to have resulted from workplace exposures or from employment at one of the places included in the Texaco mortality study.
Asbestos lung burden and asbestosis after occupational and environmental exposure in an asbestos cement manufacturing area: a necropsy study. C. Magnani, F. Mollo, L. Paoletti, et al. 1998;55(12):840-6. PubMed · Publisher · Free full text

Abstract

Objective: The largest Italian asbestos cement factory had been active in Casale Monferrato until 1986: in previous studies a substantial increase in the incidence of pleural mesothelioma was found among residents without occupational exposure to asbestos. To estimate exposure to asbestos in the population, this study evaluated the presence of histological asbestosis and the lung burden of asbestos fibres (AFs) and asbestos bodies (ABs).

Methods: The study comprises the consecutive series of necropsies performed at the Hospital of Casale Monferrato between 1985 and 1988. A sample of lung parenchima was collected and stored for 48 out of 55 necropsies. The AF concentration was measured with a TEM electron microscope with x ray mineralogical analysis. The ABs were counted and fibrosis evaluated by optical microscopy. The nearest relative of each subject was interviewed on occupational and residential history. Mineralogical and histological analyses and interviews were conducted in 1993-4.

Results: Statistical analyses included 41 subjects with AF, AB count, and interview. Subjects without occupational exposure who ever lived in Casale Monferrato had an average concentration of 1500 AB/g dried weight (gdw); Seven of 18 presented with asbestosis or small airway lung disease (SAL). G2 asbestosis was diagnosed in two women with no occupational asbestos exposure. One of them had been teaching at a school close to the factory for 12 years. Ten subjects had experienced occupational asbestos exposure, seven in asbestos cement production: mean concentrations were 1.032 x 10(6) AF/gdw and 96,280 AB/gdw. Eight of the 10 had asbestosis or SAL.

Conclusion: The high concentration of ABs and the new finding of environmental asbestosis confirm that high asbestos concentration was common in the proximity of the factory. Subjects not occupationally exposed and ever living in Casale Monferrato tended to have higher AB concentration than subjects never living in the town (difference not significant). The concentrations of ABs and AFs were higher than those found in other studies on nonoccupationally exposed subjects.
Assessment of bibliographic databases performance in information retrieval for occupational and environmental toxicology. J.F. Gehanno, C. Paris, B. Thirion, et al. 1998;55(8):562-6. PubMed · Publisher · Free full text

Abstract

Objective: To determine the efficiency of the major bibliographic databases by assessing the percentage of references among the total literature available that can be retrieved from each database. We also evaluated the best database combinations to carry out an exhaustive search.

Methods: BIOSIS, EMBASE, MEDLINE, NIOSH-TIC, and TOXLINE were searched on two topics: allergy to latex and asbestos and mesothelioma, in the title, abstract, or keywords (textwords). This search was performed for the years 1994 and 1995. All the records were classified by journal and author's name and were verified for each record whether or not it was indexed in each database. Statistical analysis was performed with chi 2 test.

Results: 777 articles in 510 issues were found. The efficiency of each database (percentage of articles recovered) and of combinations varied between 11% and 63% for one database and between 42% and 86% for a combination of two databases. The reasons why these differences exist between databases, and within a database, between two different subjects or two different years are reported.

Conclusion: Firstly, it is not advisable to assert that a bibliography is complete when only one database is searched. Secondly, the efficiency of the databases may be quite different. Finally, it is suggested that the best way to be as exhaustive as possible is to search two or more databases-for example, in EMBASE and TOXLINE, or to a lesser extent EMBASE and MEDLINE. This seems to be the best compromise solution between time consumed for searching and efficiency.
Estimation of the past and future burden of mortality from mesothelioma in France. A.G. Ilg, J. Bignon, A.J. Valleron. 1998;55(11):760-5. PubMed · Publisher · Free full text

Abstract

Objectives: Firstly to evaluate future mortality from mesothelioma in France with an age-period-cohort approach and evaluate different hypotheses on risk of mesothelioma for the most recent birth cohort. Secondly to compare the results with a British and an American study. Thirdly to study if any trends were detectable on data for women which would be consistent with the consequences of increasing environmental exposure to asbestos.

Methods: Estimates of mortality from mesothelioma among men and women in France from 1950 to 1995 were based on the analysis of the pleural cancer mortality data coded 163 in the ninth revision of the international classification of diseases (ICD-9). Correction factors were used to derive the mortality from mesothelioma from these data, based on two regional registries. The analysis of the past mortality data has been performed by an age-cohort model (with a maximum likelihood technique). Predictions of deaths from mesothelioma over the next 50 years were based on four different assumptions on the risk of death from mesothelioma in future birth cohorts.

Results: The predicted lifetime probability of dying from mesothelioma increases until the last birth cohort 1964-8 among men whereas it decreases strongly from the 1954-8 birth cohort among women. The projected numbers of deaths from mesothelioma in France until 2020 are similar, whichever hypothesis is considered: around 20,000 deaths from mesothelioma might occur among men and 2900 among women from 1996 to 2020.

Conclusions: French data show an increasing lifetime probability of death from mesothelioma in the more recent male cohorts. Although the mortality burden can be predicted until 2020, and is intermediate between the United Kingdom and United States estimates, there is still high uncertainty on the figures after 2020. No increase is found in women, and this does not support the hypothesis that current environmental exposure to asbestos could be associated with a detectable risk of death. Specific surveillance should be set up to monitor future trends or their absence.
Health survey of former workers in a Norwegian coke plant: Part. 1. Estimation of historical exposures. P.R. Romundstad, A. Rønneberg, H.L. Leira, et al. 1998;55(9):616-21. PubMed · Publisher · Free full text

Abstract

Objective: To estimate historical exposure levels at a coke plant for all agents considered to be of importance for epidemiological studies of mortality and cancer incidence.

Methods: Time weighted average exposure (8 h TWA) was estimated based on personal measurements for polycyclic aromatic hydrocarbons (PAHs) and carbonaceous particulates. Exposure to quartz was estimated relative to the concentration of carbonaceous particulates. These estimates were adjusted for the use of airstream helmets. Exposure to other agents were estimated qualitatively (asbestos, benzene, and arsenic) or semi-quantitatively (carbon monoxide (CO) and heat) based on measurements and other indicators of exposure.

Results: Exposure to PAHs was highest for those who worked at the top of the ovens (300 micrograms/m3) in the period from 1970-6. The estimated PAH exposure was reduced to an average of 65 micrograms/m3 after the introduction of exposure control measures in 1976. The estimates for carbonaceous particulates ranged from 1 to 16 mg/m3, with the highest exposure for workers at the top of the ovens and at the coke screening station.

Conclusions: The exposure of greatest concern in this study is to PAHs, but exposures to carbonaceous particulates and CO may also be of importance. The major limitations of this study are the lack of personal measurements before 1975 and the total lack of measurements for some of the exposed categories of workers. Despite these limitations, we think that this assessment reflects the actual exposures for most of the former employees. The assessment thus provides a reasonable tool for the subsequent epidemiological study and for future epidemiological follow up studies at the coke plant.
Impact of exposure to insulation wool on lung function and cough in Swedish construction workers. M. Albin, G. Engholm, N. Hallin, et al. 1998;55(10):661-7. PubMed · Publisher · Free full text

Abstract

Objectives: To investigate whether application of insulation wool adversely affects lung volumes and increases the occurrence of symptoms of airway irritation.

Methods: Data from nationwide health check ups in 1981-93 of male construction workers born in 1955 or later were used to investigate cross sectional (n = 96,004) and longitudinal (n = 26,298) associations between lung volumes, vital capacity (VC), and forced expiratory volume in one second (FEV1) and exposure to insulation wool by combining a job exposure matrix (JEM) and self reported exposure. Data on 12 month prevalence of persistent cough not associated with the common cold was available for the period 1989-92. Potential confounding from smoking, exposure to asbestos, silica, and isocyanates, was considered in the analyses.

Results: For those in the highest exposure category (self reported duration of exposure of > or = 11 years, and high exposure according to the JEM) VC was on average 2.5 cl lower (95% CI -6.5 to 1.5) than in those with no exposure. The corresponding figures for FEV1 was -2.4 cl (95% CI -6.1 to 1.3). In the longitudinal analyses, the yearly change in VC between the first and last spirometry for those in the highest exposure category was 0.50 cl (95% CI -0.97 to 1.98) less than in the unexposed category. The corresponding figure for FEV1 was 0.89 cl (95% CI - 0.70 to 2.06). High exposure to insulation wool, asbestos, or silica, during the 12 months preceding the check up was associated with increased odds ratios (ORs) for persistent cough of the same magnitude as current smoking.

Conclusions: The results indicate no effects on VC or FEV1 from exposure to insulation wool. Recent exposure to insulation wool, asbestos, and silica was associated with an increased prevalence of persistent cough.
Lung and bladder cancer in a Norwegian municipality with iron and steel producing industry: population based case-control studies. T.K. Grimsrud, H. Langseth, A. Engeland, et al. 1998;55(6):387-92. PubMed · Publisher · Free full text

Abstract

Objectives: To investigate the influence of occupation on the rising incidence of lung and bladder cancer among men in a Norwegian municipality where an iron and steel plant constituted the key industry between 1955 and 1989.

Methods: Based on the lung cancer cases reported to the Cancer Registry of Norway from 1980 to 1992 a population based case-control study was performed, including 86 cases and 196 controls. Information on occupations and smoking habits was collected through interviews and from the personnel files from the industrial plants. A case-control study on bladder cancer with 52 cases and 156 controls was carried out to cast light on the role of polycyclic aromatic hydrocarbons (PAHs).

Results: An odds ratio (OR) for lung cancer of 2.9 (95% confidence interval (95% CI) 1.2 to 6.7) was associated with exposure to PAHs. Based on data from personnel files, increased risk of lung cancer (OR 2.8 95% CI 1.1 to 7.0) was associated with work experience in the pig iron department at the ironworks. A non-significant OR of 1.8 was associated with exposure to asbestos. Bladder cancer was not associated with exposure to PAHs at the iron, steel, and coke plant, or with experience from any of the production departments at the plant.

Conclusions: One fifth of the lung cancer cases were attributed to exposure to PAHs or asbestos. More than 80% of the cases of lung cancer were attributed to tobacco smoking. The cancer risk in the pig iron department may be due to a combination of exposures to PAH, asbestos, or dust of mixed composition.
Lung cancer and mesothelioma in the pleura and peritoneum among Swedish insulation workers. B. Järvholm, A. Sandén. 1998;55(11):766-70. PubMed · Publisher · Free full text

Abstract

Objectives: To estimate the risk of cancer and death in Swedish insulation workers some years after their exposure to asbestos had stopped. One hypothesis was that the risk of lung cancer would tend to decrease some years after the exposure had ended.

Methods: In a cohort study the cancer morbidity and cause of death was investigated in 248 insulation workers and compared with the corresponding morbidity and mortality in the general population. Due to stringent regulations, exposure to asbestos of all types had almost ended in Sweden in the mid-1970s. Through a questionnaire, surviving insulation workers were asked about their exposure to asbestos and their smoking habits.

Results: Between 1970 and 1994 there were 86 deaths compared with the 46.0 expected (standardised incidence ratio (SIR) 1.9; 95% confidence interval (95% CI) 1.5 to 2.3), the increase was mainly due to an increased cancer mortality. The morbidity was increased for lung cancer (11 cases v 2.5 expected (SIR 4.4; 95% CI 2.2 to 7.9)), peritoneal mesothelioma (seven cases; no expected incidence could be calculated as the occurrence is too rare in the general population), cancer in pancreas (five cases v 0.7 expected (SIR 7.1; 95% CI 2.3 to 16.7)). No cases of pleural mesothelioma were found. The risk of lung cancer did not tend to approach that of the general population after the exposure to asbestos decreased.

Conclusions: In the 1980s and the early 1990s, Swedish insulation workers still have a highly increased risk of diseases related to asbestos. The attributable risk for death and cancer was about 50%. The study also confirms the previous finding that mesothelioma in insulation workers seems to be situated in the peritoneum more often than in the pleura.
Lung health among plumbers and pipefitters in Edmonton, Alberta. P.A. Hessel, L.S. Melenka, D. Michaelchuk, et al. 1998;55(10):678-83. PubMed · Publisher · Free full text

Abstract

Objectives: A cross sectional study was undertaken to assess lung health among plumbers and pipefitters. Respiratory symptoms, lung function, and radiographic changes among 99 actively employed plumbers and pipefitters with > or = 20 years of union membership were compared with 100 telephone workers.

Methods: A respiratory symptom questionnaire was administered, including smoking and occupational histories. Spirometry was conducted according to standard criteria. Posteroanterior chest radiographs were evaluated by two experienced chest physicians, with a third arbitrating disagreed films. Members of the union were categorised as pipefitters (n = 57), plumbers (n = 16), or welders (n = 26), based on longest service, and compared with the telephone workers and internally (between groups). Lung health was also compared with employment in several work sectors common to Alberta for time, and for time weighted by exposure to dust and fumes.

Results: Compared with the telephone workers, plumbers and pipefitters had more cough and phlegm, lower forced vital capacity, and more radiographic changes (20% with any change), including circumscribed (10%) and diffuse pleural thickening (9%). None of the plumbers and pipefitters had small radiographic opacities. Among the three subgroups of workers, plumbers had the highest prevalence of radiographic changes. Both plumbers and pipefitters showed higher odds ratios for cough and phlegm than the welders. No differences between groups were found for lung function. Indicators of lung health were not related to work in any sector.

Conclusions: Plumbers and pipefitters had increased prevalence of symptoms suggestive of an irritant effect with no evidence of bronchial responsiveness. The chest radiographs showed evidence of asbestos exposure, especially in the plumbers, but at lower levels than previously reported. Health screening programmes for these workers should be considered, although the logistical problems associated with screening in this group would be considerable.
Mortality from lung cancer and population risk attributable to asbestos in an asbestos cement manufacturing town in Italy. C. Magnani, M. Leporati. 1998;55(2):111-4. PubMed · Publisher · Free full text

Abstract

Objective: To estimate mortality from lung cancer and the risk attributable to asbestos separately for asbestos cement workers and for the general (non-occupationally exposed) population in the town of Casale Monferrato, where the largest Italian asbestos cement factory had been in operation in 1907-86. According to cancer registry data, in the same town the incidence of malignant mesothelioma in the general population is about 10 times higher than in comparable Italian provinces.

Method: Decedents from lung cancer in 1989-95 were nominally identified in the list of decedents kept at the Local Health Authority of Casale Monferrato. Workers in the asbestos cement factory have been identified with a search in the nominal list of workers and the same was done for the wives of asbestos cement workers. These lists have already been used in cohort studies. Sensitivity and specificity of the linkage procedure with occupational activity in asbestos cement production have been evaluated in a previous study. Population at risk was estimated on the basis of official figures and on the results of the cohort study of asbestos cement workers.

Results: 227 deaths from lung cancer were included (184 men and 43 women). Among the asbestos cement workers mortalities were 234.0 x 100,000 person-years among men and 35.5 among women. Corresponding figures in the general (non-occupationally exposed) population in Casale Monferrato were 80.6 and 18.7. The rates in the general population were not higher than in the rest of the region. Attributable risk (AR) among the asbestos cement workers (and wives) is 67.5% (95% confidence interval (95% CI) 56.8 to 78.2) for men and 51.3% (95% CI 14.9 to 87.8) among women. Population AR to occupational or paraoccupational exposure in the asbestos cement production is 18.3% (95% CI 11.1 to 25.6) among men and 10.1% (95% CI 0 to 24.6) among women.

Conclusion: This work did not show an increase in mortality from lung cancer for the population not exposed occupationally, but a large excess was found among men and women occupationally exposed in asbestos cement production. The total burden of lung cancer due to occupational exposure to asbestos may be underestimated, as only occupational exposure in asbestos cement production was taken into consideration. Nevertheless even a single factory can be responsible for a considerable proportion of deaths from lung cancer in a population.
Occupational exposures and squamous cell carcinoma of the oral cavity, pharynx, larynx, and oesophagus: a case-control study in Sweden. P. Gustavsson, R. Jakobsson, H. Johansson, et al. 1998;55(6):393-400. PubMed · Publisher · Free full text

Abstract

Objectives: This community based case-referent study was initiated to investigate aetiological factors for squamous cell carcinoma of the upper gastrointestinal tract.

Methods: The study was based on all Swedish men aged 40-79 living in two regions of Sweden during 1988-90. Within that base, efforts were made to identify all incident cases of squamous cell carcinoma of the oral cavity, oropharynx and hypopharynx, larynx, and oesophagus. Referents were selected as a stratified (age, region) random sample of the base. The response was 90% among cases and 85% among referents. There were 545 cases and 641 referents in the final study group. The study subjects were interviewed about several lifestyle factors and a life history of occupations and work tasks. The exposure to 17 specific agents were coded by an occupational hygienist. The relative risk (RR) of cancer was calculated by logistic regression, standardising for age, geographical region, and alcohol and tobacco consumption.

Results: Exposure to asbestos was associated with an increased risk of laryngeal cancer, and a dose-response relation was present. The RR was 1.8 (95% confidence interval (95% CI) 1.1 to 3.0) in the highest exposure group. More than eight years of exposure to welding fumes was associated with an increased risk of pharyngeal cancer (RR 2.3 (1.1 to 4.7)), and laryngeal cancer (RR 2.0 (1.0 to 3.7)). There were indications of a dose-response for duration of exposure. Associations were also found for high exposure to polycyclic aromatic hydrocarbons (PAHs) and oesophageal cancer, RR 1.9 (1.1 to 3.2). Exposure to wood dust was associated with a decreased risk of cancer at the studied sites.

Conclusions: Some of the present findings confirm known or suspected associations--such as asbestos and laryngeal cancer. The study indicates that welding may cause an increased risk of pharyngeal as well as laryngeal cancer. The findings corroborate an association between exposure to PAHs and oesophageal cancer.
Tyler asbestos workers: mortality experience in a cohort exposed to amosite. J.L. Levin, J.W. McLarty, G.A. Hurst, et al. 1998;55(3):155-60. PubMed · Publisher · Free full text

Abstract

Objectives: To examine the causes of death among 1130 former workers of a plant in Tyler, Texas dedicated to the manufacture of asbestos pipe insulation materials. This cohort is important and unusual because it used amosite as the only asbestiform mineral in the production process. High level exposure of such a specific type was documented through industrial hygiene surveys in the plant.

Methods: Deaths were ascertained through various sources including data tapes from the Texas Department of Health and the national death index files. As many death certificates as possible were secured (304/315) and cause of death assigned. After select exclusions, 222 death certificates were used in the analysis. Causes of death were compared with age, race, and sex specific mortalities for the United States population with a commercial software package (OCMAP Version 2.0).

Results: There was an excess of deaths from respiratory cancer including the bronchus, trachea, and lung (standardised mortality ratio (SMR) 277 with 95% confidence interval (95% CI) 193 to 385). Four pleural mesotheliomas and two peritoneal mesotheliomas were identified. The analysis also showed an increasing risk of respiratory malignancy with increased duration of exposure including a significant excess of total deaths from respiratory cancer with less than six months of work at the plant (SMR 268 with 95% CI 172 to 399).

Conclusions: The importance of the cohort lies with the pure amosite exposure which took place in the plant and the extended period of latency which has followed. The death certificate analysis indicates the pathogenicity of amosite, the predominant commercial amphibole used in the United States. These data confirm a link between amosite asbestos and respiratory malignancy as well as mesothelioma.
Workplace risk factors for cancer in the German rubber industry: Part 1. Mortality from respiratory cancers. S.K. Weiland, K. Straif, L. Chambless, et al. 1998;55(5):317-24. PubMed · Publisher · Free full text

Abstract

Objectives: To determine the cancer specific mortality by work area among active and retired male workers in the German rubber industry.

Methods: A cohort of 11,663 male German workers was followed up for mortality from 1 January 1981 to 31 December 1991. Cohort members were classified as active (n = 7536) or retired (n = 4127) as of 1 January 1981 and had been employed for at least one year in one of five study plants producing tyres or technical rubber goods. Work histories were reconstructed with routinely documented "cost centre codes" which were classified into six categories: I preparation of materials; II production of technical rubber goods; III production of tyres; IV storage and dispatch; V maintenance; and VI others. Standardised mortality ratios (SMRs) adjusted for age and calendar year and 95% confidence intervals (95% CIs), stratified by work area (employment in respective work area for at least one year) and time related variables (year of hire, lagged years of employment in work area), were calculated from national reference rates.

Results: SMRs for laryngeal cancer were highest in work area I (SMR 253; 95% CI 93 to 551) and were significant among workers who were employed for > 10 years in this work area (SMR 330; 95% CI 107 to 779). Increased mortality rates from lung cancer were identified in work areas I (SMR 162; 95% CI 129 to 202), II (SMR 134; 95% CI 109 to 163), and V (SMR 131; 95% CI 102 to 167). Mortality from pleural cancer was increased in all six work areas, and significant excesses were found in work areas I (SMR 448; 95% CI 122 to 1146), II (SMR 505; 95% CI 202 to 1040), and V (SMR 554; 95% CI 179 to 1290).

Conclusion: A causal relation between the excess of pleural cancer and exposure to asbestos among rubber workers is plausible and likely. In this study, the pattern of excess of lung cancer parallels the pattern of excess of pleural cancer. This points to asbestos as one risk factor for the excess deaths from lung cancer among rubber workers. The study provides further evidence for an increased mortality from laryngeal cancer among workers in the rubber industry, particularly in work area I.
A meta-analysis of the relation between cumulative exposure to asbestos and relative risk of lung cancer. T.L. Lash, E.A. Crouch, L.C. Green. 1997;54(4):254-63. Meta-analysis PubMed · Publisher · Free full text

Abstract

Objectives: To obtain summary measures of the relation between cumulative exposure to asbestos and relative risk of lung cancer from published studies of exposed cohorts, and to explore the sources of heterogeneity in the dose-response coefficient with data available in these publications.

Methods: 15 cohorts in which the dose-response relation between cumulative exposure to asbestos and relative risk of lung cancer has been reported were identified. Linear dose-response models were applied, with intercepts either specific to the cohort or constrained by a random effects model; and with slopes specific to the cohort, constrained to be identical between cohorts (fixed effect), or constrained by a random effects model. Maximum likelihood techniques were used for the fitting procedures and to investigate sources of heterogeneity in the cohort specific dose-response relations.

Results: Estimates of the study specific dose-response coefficient (kappa 1.i) ranged from zero to 42 x 10(-3) ml/fibre-year (ml/f-y). Under the fixed effect model, a maximum likelihood estimate of the summary measure of the coefficient (k1) equal to 0.42 x 10(-3) (95% confidence interval (95% CI) 0.22 to 0.69 x 10(-3)) ml/f-y was obtained. Under the random effects model, implemented because there was substantial heterogeneity in the estimates of kappa 1.i and the zero dose intercepts (Ai), a maximum likelihood estimate of k1 equal to 2.6 x 10(-3) (95% CI 0.65 to 7.4 x 10(-3)) ml/f-y, and a maximum likelihood estimate of A equal to 1.36 (95% CI 1.05 to 1.76) were found. Industry category, dose measurements, tobacco habits, and standardisation procedures were identified as sources of heterogeneity.

Conclusions: The appropriate summary measure of the relation between cumulative exposure to asbestos and relative risk of lung cancer depends on the context in which the measure will be applied and the prior beliefs of those applying the measure. In most situations, the summary measure of effect obtained under the random effects model is recommended. Under this model, potency, k1, is fourfold lower than that calculated by the United States Occupational Safety and Health Administration.
Does occupational exposure to brown coal dust cause a decline in lung function?. C. Finocchiaro, A. Lark, M. Keating, et al. 1997;54(9):642-5. PubMed · Publisher · Free full text

Abstract

Objectives: To determine if the rate of change in forced expiratory volume in one second (FEV1) in subjects with high exposure to Latrobe Valley brown coal dust was significantly greater than the rate of change among subjects with low exposure.

Methods: A retrospective dynamic cohort design with variable time windows. This study was conducted over a period of 14 years from 1980 to 1994 and used data collected by the State Electricity Commission (SEC) Lung Function Unit for an asbestos surveillance programme. The subjects were exposed to low, medium, or high levels of coal dust. Basic spirometry with wedge bellows spirometers was used to assess lung function. A general linear model (GLM) was used to assess the effects of smoking and exposure to coal dust upon the change in forced expiratory volume in one second (FEV1) while adjusting for age and height.

Results: The mean (95% confidence interval (95% CI) rate of decline in FEV1 was 40 (36 to 44) ml/year. Age was a significant predictor of change. A significant effect was found for smoking (P = 0.02) and for exposure to coal dust (P = 0.008). The only significant difference with exposure to coal dust was between the high and mixed exposure categories.

Conclusion: There is no convincing evidence of excessive decline in FEV1 with exposure to coal dust > 0.75 mg/m3. The absence of a dose response relation provides some evidence against a causal relation. On the basis of this study, reduction of the exposure standards currently applied to brown coal dust in the Victorian electricity industry is not warranted to prevent respiratory disease.
Exposure and mineralogical correlates of pulmonary fibrosis in chrysotile asbestos workers. F.H. Green, R. Harley, V. Vallyathan, et al. 1997;54(8):549-59. PubMed · Publisher · Free full text

Abstract

Objectives: The relation between lifetime cumulative exposure to asbestos, pathological grade of pulmonary fibrosis, and lung burden of asbestos at death, was explored in a necropsy population of former workers in a chrysotile asbestos textile plant in South Carolina.

Methods: Estimates of cumulative, mean, and peak exposures to asbestos were available for 54 workers. Necropsy records and lung tissue samples were obtained from hospital files. Matched control cases were selected from consecutive necropsies performed at the same hospitals. The extent and severity of pulmonary fibrosis was graded on tissue sections. Mineral fibres in lung tissue were characterised by transmission electron microscopy combined with x ray spectroscopy.

Results: A significant positive correlation (r = 0.67, P < 0.0001) was found between lifetime cumulative exposure to asbestos and total lung burden of asbestos fibres. This relation was also found for the individual types of asbestos associated with the exposure: chrysotile and tremolite. Pulmonary fibrosis was correlated with both cumulative exposure to asbestos (r = 0.60, P < 0.01) and the concentration of asbestos fibres in the lung (r = 0.62, P < 0.0001). The concentration of tremolite fibres in the lung provided a better estimate of lung fibrosis than did the concentration of chrysotile. Asbestosis was usually present in asbestos textile workers with more than 20 fibre-years cumulative exposure. The lengths and aspect ratios of chrysotile asbestos, but not amphibole asbestos, were greater in the lungs of asbestos fibre workers than in the control population. Textile workers with lung cancer had significantly greater cumulative exposures and fibrosis scores than workers without lung cancer.

Conclusions: Both cumulative exposure to asbestos and lung fibre burden are strongly correlated with severity of asbestosis. The data also support the hypothesis that the high prevalence of asbestosis and lung cancer in this population resulted from exposure to long fibres of chrysotile asbestos in the workplace.
Exposure-response analysis of risk of respiratory disease associated with occupational exposure to chrysotile asbestos. L. Stayner, R. Smith, J. Bailer, et al. 1997;54(9):646-52. PubMed · Publisher · Free full text

Abstract

Objectives: To evaluate alternative models and estimate risk of mortality from lung cancer and asbestosis after occupational exposure to chrysotile asbestos.

Methods: Data were used from a recent update of a cohort mortality study of workers in a South Carolina textile factory. Alternative exposure-response models were evaluated with Poisson regression. A model designed to evaluate evidence of a threshold response was also fitted. Lifetime risks of lung cancer and asbestosis were estimated with an actuarial approach that accounts for competing causes of death.

Results: A highly significant exposure-response relation was found for both lung cancer and asbestosis. The exposure-response relation for lung cancer seemed to be linear on a multiplicative scale, which is consistent with previous analyses of lung cancer and exposure to asbestos. In contrast, the exposure-response relation for asbestosis seemed to be nonlinear on a multiplicative scale in this analysis. There was no significant evidence for a threshold in models of either the lung cancer or asbestosis. The excess lifetime risk for white men exposed for 45 years at the recently revised OSHA standard of 0.1 fibre/ml was predicted to be about 5/1000 for lung cancer, and 2/1000 for asbestosis.

Conclusions: This study confirms the findings from previous investigations of a strong exposure-response relation between exposure to chrysotile asbestos and mortality from lung cancer, and asbestosis. The risk estimates for lung cancer derived from this analysis are higher than those derived from other populations exposed to chrysotile asbestos. Possible reasons for this discrepancy are discussed.
Lung cancer in asbestos cement workers in Denmark. M. Greenberg. 1997;54(2):143. Comment · Letter PubMed · Publisher · Free full text
Lung cancer in relation to employment in the electrical utility industry and exposure to magnetic fields. D.A. Savitz, V. Dufort, B. Armstrong, et al. 1997;54(6):396-402. PubMed · Publisher · Free full text

Abstract

Objectives: A recent study found that lung cancer may be associated with exposures encountered in the electrical utility industry. To further evaluate this possibility, data were collected and analysed from five large electrical utility companies in the United States.

Methods: A cohort of 138905 male workers employed between 1950 and 1986 was followed up for mortality to the end of 1988, with 20733 deaths identified of which 1692 were due to lung cancer. Mortality from lung cancer was examined in relation to the duration of employment in specific jobs thought to have high exposure to 60 Hz magnetic fields and to an index of cumulative exposure to magnetic fields based on personal measurements. Exposure to pulsed electromagnetic fields (PEMFs) as estimated from another study was also considered. Poisson regression generated rate ratios for categories of exposure based on comparisons within the cohort adjusted for age, calendar year, race, socioeconomic status, work status, and estimated exposure to asbestos.

Results: Mortality rose modestly with duration of work as an electrician or power plant operator reaching rate ratios of 1.4 with > or = 20 years in those jobs but not with duration of work as a lineman or a combination of jobs thought to have high exposures to 60 Hz magnetic fields or PEMFs. Cumulative indices of exposure to 60 Hz magnetic fields and PEMFs were both associated with rate ratios of 1.2-1.3 in the highest intervals.

Conclusions: These data suggest that lung cancer is not strongly associated with duration of employment in specific jobs associated with high potential exposure to 60 Hz magnetic fields or to PEMFs. Small associations of lung cancer with indices of both 60 Hz magnetic fields and PEMFs leave open the possibility that larger associations have been diluted through exposure misclassification. Refined exposure assessment, especially to PEMFs, would be required to evaluate that possibility.
Mesothelioma in a community in the north of England. M. Greenberg. 1997;54(1):67-8. Letter · Comment PubMed · Free full text
Occupational exposure to carcinogens and risk of lung cancer: results from The Netherlands cohort study. A.J. van Loon, I.J. Kant, G.M. Swaen, et al. 1997;54(11):817-24. PubMed · Publisher · Free full text

Abstract

Objectives: To investigate risk of lung cancers associated with common established carcinogenic occupational exposures (asbestos, paint dust, polycyclic aromatic hydrocarbons, and welding fumes) in a prospective cohort study among the general population, and to estimate the proportion of lung cancer cases attributable to these occupational exposures.

Methods: A prospective cohort study on diet, other lifestyle factors, job history, and cancer risk that started in 1986 in The Netherlands on 58,279 men, aged 55-69 years. Based on information about job history obtained from a self-administered questionnaire, case by case expert assessment was carried out to assign to each study subject a cumulative probability of occupational exposure for each carcinogenic exposure. For analysis, a case-cohort approach was used, in which the person-years at risk were estimated from a randomly selected subcohort (n = 1688). After 4.3 years of follow up, 524 lung cancer cases with complete job history were available.

Results: After adjustment for age, each of the other occupational exposures, and for smoking habits and intake of vitamin C, beta-carotene, and retinol, significant associations were found between risk of lung cancer and cumulative probability of occupational exposure to asbestos (relative risk (RR) highest/no exposure = 3.49, 95% confidence interval (95% CI) 1.69 to 7.18, trend P < 0.01 or paint dust (RR highest/no exposure = 2.48, 95% CI 0.88 to 6.97, trend P < 0.01). The population attributable risks (PARs) for the four exposures based on the multivariately adjusted RRs for ever exposed versus never exposed workers were calculated. The PAR of lifetime occupational exposure to asbestos was calculated to be 11.6%.

Conclusions: This prospective cohort study among the general population showed that occupational exposure to asbestos or paint dust is associated with higher RRs for lung cancer. This study shows that after adjustment for smoking and diet about 11.6% of the cases of lung cancer in men is attributable to lifetime occupational exposure to asbestos.
Occupational exposure to dust: inflammation and ischaemic heart disease. B. Sjögren. 1997;54(7):466-9. Review PubMed · Publisher · Free full text

Abstract

Objectives: To review the possible association between occupational exposure to dust and ischaemic heart disease (IHD).

Methods: A literature search was performed of relevant studies regarding IHD in specific exposures to dust. The chosen exposures were arsenic, asbestos, beryllium, lead, polycyclic aromatic hydrocarbons, and quartz. The chosen occupations were farmers, paper and paper pulp workers, sawyers, and welders.

Discussion: A theory was launched in 1995 that urban particulate air pollution may provoke alveolar inflammation, with release of mediators capable of increasing blood coagulability in susceptible people and cause cardiovascular deaths. The present review expands this hypothesis and links occupational exposure to inhaled particles with the occurrence of ischaemic heart disease.

Conclusion: This hypothesis should be tested by comparing the concentrations of fibrinogen in workers exposed and nonexposed to particles with control for other possible confounders such as smoking habits.
Physician based surveillance system for occupational respiratory diseases: the experience of PROPULSE, Québec, Canada. S. Provencher, F.P. Labrèche, L. De Guire. 1997;54(4):272-6. PubMed · Publisher · Free full text

Abstract

Objective: To evaluate the feasibility of implementing a physician based surveillance system of occupational respiratory diseases (PROPULSE) in Québec with regard to physician participation rate, characteristics of reported cases, and comparison with official statistics from the Workers' Compensation Board (WCB).

Methods: All chest physicians and allergists in Québec were asked to report suspected new cases of occupational respiratory diseases, on a monthly basis, between October 1992 and September 1993. For each case, personal information was collected and the physician's opinion on whether the condition was related to work was categorised as highly likely, likely, and unlikely.

Results: Of the 161 physicians initially approached, 68% participated. Physicians rated 48% of suspected cases as highly likely, 29% as likely, and 20% as unlikely. The most often reported diagnosis was asthma (63%), followed by diseases related to asbestos (16%). Silicosis was less frequent (5%) but it was reported for six workers under 40 of whom five were involved in sandblasting activities. The high proportion of cases of asthma probably reflects the increasing importance of this disease but may also reflect the different patterns of reporting among physicians with different expertise. The distribution of cases by diagnostic category is quite different between the PROPULSE system and that of the WCB (annual mean number of compensated cases during a four year period). Asthma and allergic alveolitis are more frequent in PROPULSE, reactive airways dysfunction syndrome are about the same in both systems, and other diseases are more frequent among compensated cases. The most frequent sensitising agents reported for asthma were the same in both systems (isocyanates, flour, and wood dust). 15% of the PROPULSE cases were not covered by the WCB, and therefore would not be found in the board's official statistics.

Conclusions: A physician based reporting procedure can be implemented as part of a surveillance system to supplement data from other sources and thus provide a better understanding of the occurrence of occupational respiratory diseases.
Progression of pleural and parenchymal disease on chest radiographs of workers exposed to amosite asbestos. J.R. Shepherd, G. Hillerdal, J. McLarty. 1997;54(6):410-5. PubMed · Publisher · Free full text

Abstract

Objectives: To determine predictors of progression of pleural and parenchymal disease on the chest radiographs of workers exposed to a short term, intense exposure of amosite asbestos.

Methods: The first and last of a series of chest radiographs of 887 workers exposed to amosite was interpreted and coded according to International Labour Organisation (ILO) standards by two physicians. Significant predictors of disease progression were found by a linear stepwise regression analysis from among such variables as smoking history, latency (time since first exposure), duration and intensity of exposure, and cytology.

Results: Although most radiographs remained normal, some showed progression of disease with about twice as many patients with abnormalities on the last film. Various combinations of age, intensity of exposure, and time between films were significant predictors of pleural and parenchymal disease and progression of such disease. No predominance of one sided disease was noted. Cytology and smoking were unreliable predictors of disease. Most disease progression was minor, usually of less than two scoring categories.

Conclusion: An intense, yet short, exposure to amosite asbestos can produce pleural and parenchymal changes on chest radiographs. The number of those affected roughly doubled over a period spanning 10 to 20 years after exposure. Age and intensity of exposure are the most important predictors of disease.
Routes of asbestos exposure and the development of mesothelioma in an English region. D. Howel, L. Arblaster, L. Swinburne, et al. 1997;54(6):403-9. PubMed · Publisher · Free full text

Abstract

Objectives: To investigate the contribution of exposure to asbestos through different routes in the development of mesothelioma.

Methods: Case-control study. 185 confirmed cases of mesothelioma and 160 controls were identified, when death had occurred between 1979 and 1991 in four health districts in Yorkshire. The surviving relatives were interviewed to ascertain lifetime exposure to asbestos. Adjusted odds ratios (ORs) of exposure to asbestos (through occupational, paraoccupational, and residential routes) were calculated for cases and were compared with controls.

Results: Likely or possible occupational exposure to asbestos was more common in cases than in controls (OR 5.6, 95% confidence interval (95% CI) 3.1 to 10.1). After excluding those with likely or possible occupational exposure, likely or possible paraoccupational exposure was more common in cases than controls (OR 5.8, 95% CI 1.8 to 19.2). Only six cases of mesothelioma were identified as being solely exposed to asbestos through their residence, compared with nine controls. The OR for residential exposure to asbestos varied between 1.5 and 6.6, depending on which potential industrial sources were included, but the 95% CIs were so wide that slightly reduced or greatly increased odds comparing cases with controls could not be excluded.

Conclusion: Study results support previous evidence that occupational and paraoccupational exposure to asbestos is associated with developing mesothelioma. Despite a rigorous search, purely residential exposure seemed to account for only 3% of identified cases. No firm conclusion can be drawn about the risks from residential exposure alone, as many of the study subjects could also have been occupationally or paraoccupationally exposed to asbestos.
Assessment of exposure to polycyclic aromatic hydrocarbons in engine rooms by measurement of urinary 1-hydroxypyrene. B.E. Moen, R. Nilsson, R. Nordlinder, et al. 1996;53(10):692-6. PubMed · Publisher · Free full text

Abstract

Objective: Machinists have an increased risk of lung cancer and bladder cancer, and this may be caused by exposure to carcinogenic compounds such as asbestos and polycyclic aromatic hydrocarbons (PAHs) in the engine room. The aim of this study was to investigate the exposure of engine room personnel to PAHs, with 1-hydroxypyrene in urine as a biomarker.

Methods: Urine samples from engine room personnel (n = 51) on 10 ships arriving in different harbours were collected, as well as urine samples from a similar number of unexposed controls (n = 47) on the same ships. Urinary 1-hydroxypyrene was quantitatively measured by high performance liquid chromatography. The exposure to PAHs was estimated by a questionnaire answered by the engine room personnel. On two ships, air monitoring of PAHs in the engine room was performed at sea. Both personal monitoring and area monitoring were performed. The compounds were analysed by gas chromatography of two types (with a flame ionisation detector and with a mass spectrometer).

Results: Significantly more 1-hydroxypyrene was found in urine of personnel who had been working in the engine room for the past 24 hours, than in that of the unexposed seamen. The highest concentrations of 1-hydroxypyrene were found among engine room personnel who had experienced oil contamination of the skin during their work in the engine room. Stepwise logistic regression analysis showed a significant relation between the concentrations of 1-hydroxypyrene, smoking, and estimated exposure to PAHs. No PAHs were detected in the air samples.

Conclusion: Engine room personnel who experience skin exposure to oil and oil products are exposed to PAHs during their work. This indicates that dermal uptake of PAHs is the major route of exposure.
Exposure to crocidolite and the incidence of different histological types of lung cancer. N.H. de Klerk, A.W. Musk, J.L. Eccles, et al. 1996;53(3):157-9. PubMed · Publisher · Free full text

Abstract

Objectives: To estimate the relations between exposure to both tobacco smoke and crocidolite and the incidence of various histological types of lung cancer.

Methods: In 1979 all former workers from the Wittenoom asbestos industry who could be traced were sent a questionnaire on smoking history. Of 2928 questionnaires sent, satisfactory replies were received from 2400 men and 149 women. Of the men, 80% had smoked at some time and 50% still smoked. Occupational exposure to crocidolite was known from employment records and follow up was maintained through death and cancer registries in Australia with histological diagnoses obtained from the relevant State Cancer Registry. Conditional logistic regression was used to estimate the effects of tobacco and asbestos exposure on incidence of different cell types of lung cancer in a nested case-control design.

Results: Between 1979 and 1990, 71 cases of lung cancer occurred among men in this cohort: 27% squamous cell carcinoma, 31% adenocarcinoma, 18% small cell carcinoma, 11% large cell carcinoma, and 13% unclassified or indeterminate. Two of the classified cases and one unclassified case had never smoked. The incidence of both squamous and adenocarcinoma types of lung cancer were greatest in ex-smokers and in those subjects with the highest levels of exposure to crocidolite. After adjustment for smoking habit, the increase in incidence of lung cancer with increasing exposure to crocidolite was greater for squamous cell carcinoma than for adenocarcinoma.

Conclusions: The results from this study have shown significant exposure-response effects for exposure to crocidolite, and both adenocarcinoma and squamous cell carcinoma of the lung. They also provide some further evidence against the theory that parenchymal fibrosis induced by asbestos is a necessary precursor to asbestos induced lung cancer.
Incidence of cancer among Norwegian boiler welders. T.E. Danielsen, S. Langård, A. Andersen. 1996;53(4):231-4. PubMed · Publisher · Free full text

Abstract

Objectives: The cancer incidence among 2957 boiler welders was investigated. The subjects were registered electrical welders from 1942 to 1981. A subcohort of 606 stainless steel welders was studied separately.

Methods: The investigation was a historical prospective cohort study based on a national registry. The loss of follow up was 4.9%.

Results: There were 625 deaths (659 expected). There were 269 cancer cases (264 expected). An excess of lung cancer was found; 50 cases v 37.5 expected. There were three cases of pleural mesotheliomas v 1.1 expected. The subcohort of stainless steel welders had six cases of lung cancer v 5.8 expected, and one case of pleural mesothelioma v 0.2 expected.

Conclusions: The welders in the study were assumed to represent a qualified work force. These welders had a small excess risk of lung cancer. The excess risk did not seem to be associated with stainless steel welding. Smoking and asbestos exposure were potential confounders.
Lung cancer in asbestos cement workers in Denmark. E. Raffn, E. Villadsen, G. Engholm, et al. 1996;53(6):399-402. PubMed · Publisher · Free full text

Abstract

Objectives: To study the relative and absolute risks of main types of lung cancer in a cohort of asbestos cement workers from Denmark.

Method: A cohort of 7887 men and 576 women employed between 1928 and 1984 was compiled from the personnel files of Danish Eternit Production. The cohort was followed up for deaths, emigrations, and incident cancer cases during the period 1943-90. The observed number of lung cancer cases in the cohort was compared with the expected number based on incidences for the Danish population. Internal comparison was made with Poisson modelling.

Results: A total of 226 lung cancer cases were observed (223 men and three women). The standardised incidence ratio (SIR) for all lung cancer among men was 1.7 (observed number 223, expected number 129.7, 95% confidence interval (95% CI) 1.5-2.0). The SIRs were raised for all main types of lung cancer; adenocarcinoma 2.6, squamous cell carcinoma 1.7, and anaplastic carcinoma 1.5. The higher SIR for adenocarcinomas was found particularly with a latency period of 25 years or more. Among the 93 excess lung cancer cases, 36 were squamous cell carcinomas and 32 were adenocarcinomas.

Conclusion: Asbestos cement work is associated with an increased risk of lung cancer of all main types. During the first 25 years after the start of employment this excess risk is shared almost equally between the different histological types of lung cancer, but the risk of adenocarcinomas is clearly higher after this point.
Lung cinescintigraphy in the dynamic assessment of ventilation and mucociliary clearance of asbestos cement workers. L. Di Lorenzo, M. Mele, M.M. Pegorari, et al. 1996;53(9):628-35. PubMed · Publisher · Free full text

Abstract

Objectives: To verify in vivo whether lung cinescintigraphy confirms the effect of asbestos on the patency of the smallest airways and on the efficiency of mucociliary clearance in asbestos cement workers.

Methods: 39 male subjects were examined: 30 asbestos cement workers and nine workers never exposed to occupational respiratory irritants. All subjects had a chest radiograph (International Labour Organisation (ILO) 1980); standard questionnaire on chronic bronchitis; spirometry; arterial blood gas analysis; carbon monoxide transfer factor (TLcosb); pulmonary O2 and CO2 ductances (DuO2, DuCO2); electrocardiogram; and lung cinescintigraphy after radioaerosol inhalation for the measurement of mucociliary clearance time in vivo in the smallest ciliated airways and for the assessment of radioaerosol deposition in alveoli (alveolar deposition index).

Results: Apart from nine non-exposed subjects, the 30 asbestos cement workers were so classified on the basis of chest radiography: nine of them as healthy exposed, 10 with pleural plaques, and 11 with asbestosis. The four groups had similar ages, work seniority, and smoking habits. Exercise dyspnoea was significantly more frequent in asbestos cement workers. Lung function variables of workers with effects related to asbestos were significantly lower than the other two groups. The PaO2, TLcOsb and DuO2 mean values were significantly lower in exposed workers than non-exposed. The mean PacO2 value was significantly higher in the asbestosis group than in the other three groups. Workers with effects related to asbestos showed a significantly lower alveolar deposition index and a significantly higher mucociliary clearance time than the other two groups. Subjects with asbestosis showed similar differences from those with pleural plaques.

Conclusions: Lung cinescintigraphy confirms in vivo the effects of asbestos on bronchiolar and alveolar patency and on efficiency of mucociliary clearance in the smallest ciliated airways. Finally, lung cinescintigraphic variables are able to discriminate workers with asbestosis from those with pleural plaques.
Mesothelioma in a community in the north of England. A.T. Edward, D. Whitaker, K. Browne, et al. 1996;53(8):547-52. PubMed · Publisher · Free full text

Abstract

Objectives: To find the numbers of mesotheliomas in Calderdale over the period 1966-94 and determine their relation to asbestos exposure, pathology, and mineral fibre burden within the lungs of affected subjects.

Methods: Cases were entered into the study if the subject has been diagnosed with mesothelioma after postmortem and histopathological examinations. Occupational data were obtained mainly from the case records of the Cape Asbestos medical officer, hospital, and medical practitioner and from death certificates. Analyses of the mineral fibres were performed with transmission electron microscopy and energy dispersive x ray spectrometry.

Results: 73 mesotheliomas were diagnosed from 1966 to 1994. Forty four were associated with exposure at the Acre Mill factory, which manufactured asbestos products. Concentrations of amphibole asbestos fibres were found to be raised above controls in 31 out of 32 cases associated with Acre Mill exposure, in 10 out of 12 other cases exposed to asbestos and eight out of 17 cases not exposed to asbestos.

Conclusions: There was a high number of mesotheliomas in Calderdale. More than half of the cases were associated with occupation at the Acre Mill factory and were associated with exposure to amphibole asbestos, predominantly crocidolite. No cases associated with neighbourhood exposure to asbestos were identified.
Reanalysis of mortality from lung cancer among diatomaceous earth industry workers, with consideration of potential confounding by asbestos exposure. H. Checkoway, N.J. Heyer, P.A. Demers, et al. 1996;53(9):645-7. PubMed · Publisher · Free full text

Abstract

Objective: To evaluate the potential for confounding from asbestos exposure, primarily chrysotile, on the relation between crystalline silica and mortality from lung cancer among diatomaceous earth (diatomite) workers.

Methods: A reanalysis of a cohort mortality study of diatomite workers was performed to take into account quantitative estimates of asbestos exposure. The reanalysis was limited to a subset of the original cohort, comprising 2266 white men for whom asbestos exposure could be reconstructed with greatest confidence. Comparisons between mortality from lung cancer (standardised mortality ratios (SMR)) were made between rates for 1942-87 for United States white men, and workers cross classified according to cumulative exposures to crystalline silica and asbestos. Comparisons of internal rates, involving Poisson regression modeling, were conducted for exposure to crystalline silica, with and without adjustment for asbestos exposure. Exposures were lagged by 15 years to take into account disease latency.

Results: There was an overall excess of lung cancer (SMR 1.41; 52 observed). The SMRs for four categories of increasing crystalline silica among the workers not exposed to asbestos were 1.13, 0.87, 2.14, 2.00. An SMR of 8.31 (three observed) was found for workers with the highest cumulative exposure to both dusts. Internal analysis, after adjustment for asbestos exposure, yielded rate ratios for categories of exposure to crystalline silica: 1.00 (reference), 1.37, 1.80, and 1.79.

Conclusions: Asbestos exposure was not an important confounder of the association between crystalline silica and mortality from lung cancer in this cohort. Although based on a small number of deaths from lung cancer, the data suggest possible synergy between these exposures. An extended follow up of this cohort is in progress and should enable better assessments of independent and combined effects on risk of lung cancer.
Relation of spirometric function to radiographic interstitial fibrosis in two large workforces exposed to asbestos: an evaluation of the ILO profusion score. A. Miller, R. Lilis, J. Godbold, et al. 1996;53(12):808-12. PubMed · Publisher · Free full text

Abstract

Objectives: To analyse quantitatively the relations of spirometric lung function (forced vital capacity (FVC)) to radiographic interstitial pulmonary fibrosis (assessed by the International Labour Organisation (ILO) profusion score of small irregular opacities) in two large workforces exposed to different intensities of asbestos. These analyses consider the question whether a similar profusion score n differently exposed workers is associated with a similar effect on lung function.

Methods: Surveys of two workforces, insulators (n = 2611) and sheet metal workers (n = 1245), by the same investigators allowed comparison of the effects of the two levels of exposure to asbestos. The two groups were of similar age and had similar percentages of non-smokers and smokers. All radiographs were read by the same expert reader.

Results: Consistent with their less continuous and less intense exposure to asbestos, metal workers had: (a) far less frequent radiographic asbestosis (profusion score > or = 1/0, 17.5% v 59.6% for insulators): (b) less severe radiographic asbestosis (only 1.1% had scores > or = 2/1 v 13.3% of insulators); (c) a similar slope to that seen in insulators for the relation between FVC and profusion score when pleural thickening was absent; (d) less frequent pleural fibrosis (36% v 75%); and (e) less frequent restrictive impairment (23% v 33%). In both insulators and metal workers, lung function was below normal even when lung fields were normal, FVG fell with increasing profusion, it was lower in smokers and in those with pleural thickening at comparable profusion scores, and these was no difference in FVC between scores 0/1 and 1/0.

Conclusion: The decrease in FVC with increasing profusion score in both workforces as well as the similar slopes for the relation between FVG and profusion score and the similar FVG at similar scores in the absence of pleural thickening confirm the ILO profusion score as an acceptable assessment of pulmonary fibrosis.
Retention of asbestos fibres in lungs of workers with asbestosis, asbestosis and lung cancer, and mesothelioma in Asbestos township. A. Dufresne, R. Bégin, S. Massé, et al. 1996;53(12):801-7. PubMed · Publisher · Free full text

Abstract

Objective: To conduct a mineralogical study on the particles retained in the necropsied lungs of a homogenous group of asbestos miners and millers from Asbestos township (and a local reference population) and to consider the hypothesis that there is a difference in size between fibres retained in the lungs of patients with asbestosis with and without lung cancer.

Methods: Samples of lung tissue were obtained from 38 patients with asbestosis without lung cancer, 25 with asbestosis and lung cancer, and 12 with mesothelioma, from necropsied Quebec chrysotile miners and millers from Asbestos township. Fibre concentrations in the lungs of these patients were compared with those in tissue from necropsies carried out on a local reference population: men who had died of either accidental death or acute myocardial infarction between 1990 and 1992. 23 were born before 1940 and 26 after 1940.

Results: Geometric mean (GM) concentrations were higher in cases than in the controls for chrysotile fibres 5 to 10 microns long in patients with asbestosis with or without lung cancer; for tremolite fibres 5 to 10 microns long in all patients; for crocidolite, talc, or anthophyllite fibres 5 to 10 microns long in patients with mesothelioma; for chrysotile and tremolite fibres > or = 10 microns long in patients with asbestosis; and crocidolite, talc, or anthophyllite fibres > or = 10 microns long in patients with mesothelioma. However, median concentrations of each type of fibre in the lungs did not show any significant differences between the three disease groups. Average length to diameter ratios of the fibres were calculated to be larger in patients with asbestosis and lung cancer than in those without lung cancer for crocidolite fibres > or = 10 microns long, for chrysotile, amosite, and tremolite fibres 5 to 10 microns long, and for chrysotile and crocidolite fibres < 5 microns long. However, there was no statistical difference in the median length to diameter ratios for any type of fibres across the disease groups when they were calculated in each patient. Cumulative smoking index (pack-years) was higher in the group with asbestosis and lung cancer but was not statistically different from the two other disease groups.

Conclusion: Lung cancers occurred in workers with asbestosis from Asbestos township who had an equal concentration of retained fibres but a tendency to a higher length to diameter ratio of amphiboles. These workers had a 29% higher average cumulative smoking index.
Survival in cohorts of asbestos cement workers and controls. M. Albin, V. Horstmann, K. Jakobsson, et al. 1996;53(2):87-93. PubMed · Publisher · Free full text

Abstract

Objectives: To measure the impact on survival of being exposed to asbestos cement dust.

Methods: Survival of 866 asbestos cement workers and 755 controls was studied with Cox's proportional hazards regression models with age as the basic time variable. The effect of cumulative exposure up to the age of 40 was investigated in an internal analysis of 635 asbestos cement workers who had dose estimates.

Results: The death risk was higher for the asbestos cement workers than for the controls with a hazard ratio (HR) of 1.15 (95% confidence interval was 1.00 to 1.31). The increased risk found seemed to be confined to the period 20-40 years from start of employment. The estimates of the cohort effect were almost unaffected by adjustment for smoking habits. The estimates of the exposure effect rose with increasing dose (< 4 fibre-years/ml (f-y/ml): HR = 1.00, 4-9.9 f-y/ml: HR = 1.06, > or = 10 f-y/ml: HR = 1.35, for workers with at least five years of employment), and were higher when restricted only to deaths from malignant or non-malignant respiratory disease. However, none of the point estimates were significantly increased. Median age at death was two years lower in the high than in the low, exposure group.

Conclusions: The results indicate that even a moderate asbestos exposure may shorten the median duration of life in an exposed population. Compared with the estimated effect on duration of life from ever being a smoker, that of ever being an asbestos cement worker was less, although that of having a high exposure was similar.
Decline in annual lung function in workers exposed to asbestos with and without pre-existing fibrotic changes on chest radiography. T. Nakadate. 1995;52(6):368-73. PubMed · Publisher · Free full text

Abstract

Objectives: To examine whether or not workers with pre-existing mild pulmonary fibrosis have accelerated decline in forced expiratory volume in one second (FEV1) or forced vital capacity (FVC), under low level exposure to chrysotile asbestos.

Methods: All male workers in two asbestos manufacturing factories were followed up annually for six years to compare their declines in FEV1 and FVC. The values of FEV1 and FVC were divided by the square of the person's height to adjust for body size differences (FEV1/Ht2 and FVC/Ht2, respectively). Annual change was calculated for each subject as a slope of the simple linear regression with FEV1/Ht2 or FVC/Ht2 regressed according to age. Analysis was conducted on 242 middle aged workers who had normal routine spirometry values, normal chest radiographs or mild pneumoconiosis up to 1/2 grade, without changes either in smoking habit or severity of pneumoconiosis during the study period, and with acceptable spirograms in three or more surveys. The occupational environment, in terms of chrysotile asbestos, had been well controlled below the threshold limit value of Japan at that time--namely, 2 fibres/micromilligrams. RESULTS-There was no significant effect from the interaction between pre-existing mild pulmonary fibrosis and low level of exposure to chrysotile asbestos on the accelerated annual decline of FEV1/Ht2, or FVC/Ht2. Fibrosis significantly contributed to annual changes in FEV1/Ht2, even after adjustment for mean FEV1 and smoking. The point estimate of the contribution was - 4.9 ml/m2/y. No significant independent contribution of exposure was found in decline of either FEV1/Ht2 or FVC/Ht2.

Conclusions: Pre-existing pulmonary fibrosis is an independent risk factor for accelerated annual decline of FEV1, even when mild and stable. Additional decline due to exposure to chrysotile asbestos is less probable if it is well controlled under the current threshold limit value.
Differences in occupational mortality from pleural cancer, peritoneal cancer, and asbestosis. D. Coggon, H. Inskip, P. Winter, et al. 1995;52(11):775-7. PubMed · Publisher · Free full text

Abstract

Objective: To assess whether the increased risk of disease related to asbestos in occupations from the construction and engineering industries applies equally to pleural cancer, peritoneal cancer, and asbestosis.

Methods: Analysis was based on deaths among men aged 20-74 in England and Wales during 1979-80 and 1982-90. (n = 1,656,096). Information about cause of death and the last full time occupation of decedents was derived from death certificates. Proportional mortality ratios (PMRs) by occupation were calculated for each of pleural cancer, peritoneal cancer, and asbestosis.

Results: Altogether, 2848 deaths were attributed to cancer of the pleura, 362 to cancer of the peritoneum, and 281 to asbestosis. When occupations were ranked according to PMRs from these diseases, striking differences were found. The category of construction workers which included laggers had the highest mortality from peritoneal cancer (PMR 990, 64 deaths), but a PMR of only 160 (77 deaths) for pleural cancer. In contrast, several occupations with much higher mortality from pleural tumours had no excess of peritoneal cancer. PMRs for asbestosis related more closely to those for peritoneal than pleural cancer.

Conclusions: These findings suggest that the exposure-response relations for diseases related to asbestos are not all linear, and that risks of pleural mesothelioma may be underestimated by simple extrapolation from observations in cohorts with heavy exposure.
Differential release of superoxide anions by macrophages treated with long and short fibre amosite asbestos is a consequence of differential affinity for opsonin. I.M. Hill, P.H. Beswick, K. Donaldson. 1995;52(2):92-6. PubMed · Publisher · Free full text

Abstract

Objective: To investigate the ability of short and long fibre samples of amosite asbestos to stimulate superoxide production in isolated rat alveolar macrophages, and to determine how opsonisation with rat immunoglobulin might modify this response.

Methods: Macrophages were isolated from rat lung by bronchoalveolar lavage and challenged with both opsonised and non-opsonised long and short fibres of amosite asbestos. Release of superoxide anions was measured by the spectrophotometric reduction of cytochrome c, in the presence and absence of superoxide dismutase.

Results: Both long and short fibre samples of amosite asbestos without opsonisation were ineffective in stimulating isolated rat alveolar macrophages to release superoxide anions in vitro. After opsonisation with immunoglobulin, however, a dramatic enhancement of release of superoxide anion was seen with long fibres, but not short, which confirms the importance of fibre length in mediating biological effects. The increased biological activity of the long fibre sample is explained by increased binding of the opsonin to the fibre surface as, at equal mass, the long fibres bound threefold more immunoglobulin than the short fibres.

Conclusion: Opsonisation is an important factor in modulation of the biological activity of fibres at the cellular level. Differences in binding of opsonin to samples of fibre previously considered to be identical apart from length, suggest that surface reactivity needs to be taken into account when fibres are compared. Binding of biological molecules, in vivo, may thus be an important modifying factor in the pathological processes initiated by fibres.
Fibrogenic effect of wollastonite compared with asbestos dust and dusts containing quartz. E.E. McConnell. 1995;52(9):621. Comment · Letter PubMed · Publisher · Free full text
Health effects of refractory ceramic fibres: scientific issues and policy considerations. L.R. Glass, R.C. Brown, J.A. Hoskins. 1995;52(7):433-40. Review PubMed · Publisher · Free full text

Abstract

Objectives: To review the scientific literature on the health effects of refractory ceramic fibres (RCFs). The adverse effects of exposure to asbestos has led to concern about the potential for other fibrous materials to cause diseases. For this reason the human populations most heavily exposed to synthetic mineral fibres have been examined for any adverse effects and many types of fibre have been studied in animal experiments. One type of man made vitreous fibres (MMVFs), refractory ceramic fibres (RCFs), are principally used in thermal insulation at high temperatures--up to 1400 degrees C. As manufactured RCFs exist in a glassy, non-crystalline (sometimes called amorphous) state, they have various compositions, physical properties, and sized fibres.

Methods: All reports on the health effects of RCFs available up to the end of 1994 have been examined and the scientific literature reviewed although all publications have not necessarily been referenced.

Conclusions: In recent inhalation experiments conducted with both rats and hamsters at the Research and Consulting Company, Geneva, at the highest dose tested (30 mg/m3) there was an increased incidence of tumours in both species. Lower doses were only examined in the rat and at these doses there was no significant excess of lung tumours. Epidemiological investigations of workers engaged in the manufacture of ceramic fibres have shown a small excess of pleural plaques. This phenomenon is being further investigated but could be due to confounding exposures. The populations available for study are small and their exposures fairly short, but it is considered prudent that they should remain under surveillance for some time to come. This is despite the fact that present exposures in the ceramic fibre industry are low (< 1 f/ml) and are being reduced.
Mortality and cancer morbidity in workers from an aluminium smelter with prebaked carbon anodes--Part I: Exposure assessment. A. Rønneberg. 1995;52(4):242-9. PubMed · Publisher · Free full text

Abstract

Objectives: To design a job-exposure matrix for epidemiological studies of men who had worked in a Norwegian aluminium smelter between 1922 and 1975.

Methods: Jobs held by cohort members were identified from personnel records. Tasks and their locations were determined for all jobs, and information was gathered about changes in exposure conditions over time. The jobs were combined into categories thought to have experienced similar exposure conditions, and time weighted average exposures were estimated on a relative scale. The results were reviewed by a panel of former smelter employees and an experienced industrial hygienist.

Results: 96 different jobs could be identified from the cohort members' work histories. These were grouped into 18 categories, and relative exposure intensities were estimated for 31 different combinations of category and period. The most prevalent exposure in the cohort was pot emissions (fluorides, sulphur dioxide, and carbon monoxide; 74% ever exposed), followed by magnetic fields and heat stress (65-68%), asbestos (40%), and coal tar pitch volatiles (33%).

Conclusions: Although the use of this job-exposure matrix in the subsequent epidemiological studies may result in some misclassification of exposure, this is unlikely to seriously attenuate true risks in a stratified analysis based on cumulative exposure.
Mortality and cancer morbidity in workers from an aluminium smelter with prebaked carbon anodes--Part II: Cancer morbidity. A. Rønneberg, A. Andersen. 1995;52(4):250-4. PubMed · Publisher · Free full text

Abstract

Objective: To investigate associations between cancer incidence and exposure to coal tar pitch volatiles, asbestos, pot emissions (fluorides, sulphur dioxide), heat stress, and magnetic fields in workers from a Norwegian aluminium smelter that operated from 1914 to 1975.

Methods: Cancer incidence between 1953 and 1991 was recorded in a cohort of 1137 men hired between 1922 and 1975. The expected number of cancer cases was calculated from incidence rates in Norwegian men. A job exposure matrix with semiquantitative exposure estimates was used to investigate associations between cumulative exposure estimates was used to investigate associations between cumulative exposure and cancer incidence through exploring temporal relations by considering exposures only within specific time windows.

Results: A significant excess of cancer cases, 90 observed v 59.0 expected, was found in workers who had been employed for less than three years. No such excess was found in men with at least three years' employment, with 120 cases observed v 129.7 expected. In this subcohort an association was found between the incidence of bladder cancer and exposure to coal tar pitch volatiles 40 years or more before each person-year under observation, and between incidence of lung cancer and tar exposure 35-50 years before observation. An association was also found between incidence of kidney cancer and exposure to heat stress 20-35 years before observation.

Conclusions: The results support previous findings that exposure to coal tar pitch volatiles in the aluminium industry has been associated with increased risk of bladder and lung cancer. They also add information about temporal relations, suggesting that exposure to tar in this smelter has acted on an early stage in the development of these cancers, followed by a latency period of 30-40 years.
Pleural malignant mesothelioma and non-occupational exposure to asbestos in Casale Monferrato, Italy. C. Magnani, B. Terracini, C. Ivaldi, et al. 1995;52(6):362-7. PubMed · Publisher · Free full text

Abstract

Objectives: To assess and quantify the occurrence of pleural malignant mesotheliomas in people who neither experienced occupational exposure to asbestos nor were married to (or known to live with) workers exposed to asbestos in the workplace. The study was conducted in the area of the local health authority of Casale Monferrato, in north western Italy, where a large factory that produced asbestos cement was active up to 1985. No other major activities related to asbestos have ever been present in the area.

Methods: A retrospective survey covering the period 1980 to 1991 identified 126 incident pleural malignant mesotheliomas histologically diagnosed among residents in the local health authority (population at the 1981 census 98,000). Submission of 83 of 95 cases diagnosed during 1980-9 for revision by a panel of five expert pathologists led to the exclusion of 21. The 31 cases diagnosed in 1990-1 were not submitted for revision. For 64 of the 105 retained cases, information derived from different sources (rosters of the employees in the asbestos cement factory dated back to 1907, list of their spouses, clinical records) did not suggest occupational or paraoccupational exposure to asbestos.

Results: Incidence excludes cases for which there was some suggestion of occupational or paraoccupational exposure to asbestos. Incidence of histologically confirmed malignant mesothelioma among residents in the local health authority (annual x 100,000; age adjusted) was 4.2 in men and 2.3 in women (based on 26 and 18 cases respectively). In both sexes, rates in 1985-9 were higher than in the previous quinquennium. Corresponding estimates for 1990-1 (based on unrevised diagnoses) suggest similar rates in men and women.

Conclusion: Rate ratios which are four to six times those measured by conventional Italian cancer registries can hardly be totally explained by bias produced by lack of recognition of occupational or paraoccupational exposure. The problem of proving this type of negative data is common to other circumstances of alleged cancer clusters of environmental (non occupational) origin.
Potential public health problems of asbestos in Jamaica. H.O. Reid, I.A. Kahwa. 1995;52(3):214. Letter PubMed · Publisher · Free full text
Radiological changes in asbestos cement workers. K. Jakobsson, U. Strömberg, M. Albin, et al. 1995;52(1):20-7. PubMed · Publisher · Free full text

Abstract

Objective: To explore associations between exposure to asbestos cement dust and radiographic findings in lung parenchyma and pleura.

Methods: Radiographs from 174 blue collar workers and 29 white collar workers from an asbestos cement plant formed one part of the study. Progression of small opacities was further studied in those 124 blue collar workers, for whom two radiographs taken after the end of employment were available. The median readings from five readers who used the full ILO 1980 classification were used. As exposure indices, time since start of employment, duration of employment, cumulative exposure, and average intensity of asbestos exposure were used. The influence of age and smoking was also considered in multiple logistic regression analyses.

Results: Small opacities (profusion > or = 1/0) were closely correlated with time related exposure variables, and showed weaker association with intensity based exposure variables. The odds ratio (OR) for small opacities was equal to 2.8 (90% CI 1.2, 6.7) in the > 30 f(fibre)-y/ml group, compared with those in the 0-10 f-y/ml group. Progression of at least two minor ILO categories after the end of employment was seen in 20%. Also, pleural thickening was closely related to time. By contrast, costophrenic angle obliterations were not associated with the time related variables, but closely associated with the intensity of asbestos exposure, and tended to occur during employment. The OR was 4.5 (90% CI 1.3, 15) in the > 2 f/ml group, compared with those in the 0-1 f/ml group.

Conclusions: In these workers, exposed mainly to chrysotile but also to small amounts of amphibole, the risk of radiographically visible parenchymal abnormality was substantially increased and strongly dependent on time related exposure variables. Progression was found long after the end of exposure. The findings on costophrenic angle obliterations, supposed to be sequelae of benign pleural effusions, were consistent with an immediate reaction triggered by intense asbestos exposure.
Respiratory health of workers exposed to metal dusts and foundry fumes in a copper refinery. G. Ostiguy, C. Vaillancourt, R. Bégin. 1995;52(3):204-10. PubMed · Publisher · Free full text

Abstract

Objectives: To assess airflow limitation in workers exposed long term to metal dust, the prevalence of pleural plaques in those workers exposed in the past to asbestos, the influence of pleural plaques on lung function, and the possible association with airway disease caused by asbestos.

Methods: A cross sectional and longitudinal (seven year) survey of 494 long term (mean (SEM) 21(1) years) workers in a copper refinery was carried out from medical questionnaires, chest radiographs, and forced spirometry.

Results: The prevalence of lifetime non-smokers was 19%, current smokers 39%, and ex-smokers 42%. The prevalence of chronic obstructive pulmonary diseases (COPD) (forced expiratory volume in one second (FEV1) < 80% predicted) was 5%, small airway dysfunction (SAD) (maximal mid-expiratory flow (MMEF) < 60% predicted) was 7%, and this did not differ from the control population. The COPD and SAD were associated with cumulative smoking index but not with the cumulative work years at the plant or with any type of work at the plant. The mean (SEM) reduction of FEV1 was 20(7) ml in non-smokers, 26(4) ml in smokers, and 26(5) ml in ex-smokers (P > 0.05). In the smokers and ex-smokers with COPD, the loss of FEV1 was 53(10) (P < 0.02). The prevalence of pleural plaques was 11% (P < 0.0001); pleural plaques were found in older workers with known exposure to asbestos. The pleural plaques were circumscribed and associated with a non-significant 196 ml reduction in forced vital capacity (FVC) and non-significant reduction of FVC over time. The pleural plaques were not associated with COPD or SAD. The cumulative smoking index obtained by a technician did not differ from that by a chest physician.

Conclusions: Despite exposures to asbestos that produced pleural plaques and exposures to metal dusts and foundry fumes the long term workers of this plant did not have excessive prevalence of COPD or SAD. The data suggest that low level long term exposure to metal dusts, gases, and foundry fumes do not necessarily cause respiratory dysfunction, circumscribed pleural plaques with low grades of width and extent do not reduce FVC significantly, and exposure to asbestos dust that produced pleural plaques does not necessarily produce airway dysfunction.
Asbestos fibres and man made mineral fibres: induction and release of tumour necrosis factor-alpha from rat alveolar macrophages. A.G. Ljungman, M. Lindahl, C. Tagesson. 1994;51(11):777-83. PubMed · Publisher · Free full text

Abstract

Objectives: Mounting evidence suggests that asbestos fibres can stimulate alveolar macrophages to generate the potent inflammatory and fibrogenic mediator, tumour necrosis factor-alpha (TNF-alpha), and that this may play an important part in the onset and development of airway inflammation and lung fibrosis due to asbestos fibre inhalation. Little is known, however, about the ability of other mineral fibres to initiate formation and release of TNF-alpha by alveolar macrophages. Therefore the effects of different fibres (crocidolite, chrysotile A, chrysotile B, two man made mineral fibres (MMVF 21 and MMVF 22), a ceramic fibre (RCF 1), and a silicon carbide whisker fibre (SiCwh)) on formation and release of TNF-alpha by rat alveolar macrophages were examined.

Methods: Cells were isolated and incubated at 37 degrees C with the different fibres, or with culture medium alone (controls), and the amounts of TNF-alpha messenger RNA (mRNA) in the cells and TNF-alpha bioactivity released into the culture medium were measured at different time points.

Results: Significantly (P < 0.05 v control) increased amounts of TNF-alpha mRNA were found in cells exposed to crocidolite, chrysotile A, chrysotile B, MMVF 21, RCF 1, or SiCwh for 90 minutes, and significantly (P < 0.05 v control) increased activities of TNF-alpha were found in the medium of macrophages exposed to crocidolite, chrysotile A, chrysotile B, or MMVF 21 for four hours.

Conclusion: These observations suggest that not only natural mineral fibres but also certain man made mineral fibres are able to induce the formation and release of TNF-alpha by alveolar macrophages in vitro.
Asbestos, cement, and cancer in the right part of the colon. K. Jakobsson, M. Albin, L. Hagmar. 1994;51(2):95-101. PubMed · Publisher · Free full text

Abstract

Objective: The aim was to investigate associations between exposure to mineral fibres and dust, and cancer in subsites within the large bowel.

Design: Pooled retrospective cohort studies.

Subjects And Settings: Blue collar workers, employed for at least one year in different trades; asbestos cement or cement workers (n = 2507), other industrial workers (n = 3965), and fishermen (n = 8092).

Main Outcome Measures: Standardised incidence ratios (SIRs, national reference rates) were calculated for cause specific cancer morbidity between 1958 and 1989. The observation period began 15 years after first employment.

Results: The asbestos cement and cement workers had a slightly increased risk of colorectal cancer (SIR 1.5; 95% confidence interval (95% CI) 1.1-2.0). This was due to an increase only in the right part of the colon (SIR 2.5; 95% CI 1.6-3.8). The ratio of right (7th revision of the International Classification of Diseases ICD-7) 1530-1531)/left (ICD-7 1532-1533) colon cancer among the asbestos cement and cement workers of 4.8 differed significantly from the ratio both among the other blue collar workers (0.4) and among the fishermen (1.5). As the sensitivity and accuracy was insufficient, mortality data did not show the excess of cancers in the right part of the colon.

Conclusions: An increased incidence of cancer in the right part of the colon was evident in the asbestos cement and cement workers. The distribution of cancers within the colon was noticeably different from that in other blue collar workers, indicating that our findings cannot be explained by socioeconomic confounding factors. A detailed and appropriate disease classification, based on incidence data, is necessary in order not to obscure or underestimate effects of exposure in epidemiological studies on colorectal cancer.
Deposition and retention of inhaled fibres: effects on incidence of lung cancer and mesothelioma. M. Lippmann. 1994;51(12):793-8. Review PubMed · Publisher · Free full text

Abstract

A review of the literature on chronic inhalation studies in which rats were exposed to mineral fibres at known fibre number concentrations was undertaken to examine the specific roles of fibre length and composition on the incidences of both lung cancer and mesothelioma. For lung cancer, the percentage of lung tumours (y) could be described by a relation of the form y = a + bf + cf2, where f is the concentration of fibre numbers and a, b, and c are fitted constants. The correlation coefficients for the fitted curves were 0.76 for > 5 microns f/ml, 0.84 for > 10 microns f/ml, and 0.85 for > 20 microns f/ml. These seemed to be independent of fibre type. It has been shown that brief inhalation exposures to chrysotile fibre produces highly concentrated fibre deposits on bifurcations of alveolar ducts, and that many of these fibres are phagocytosed by the underlying type II epithelial cells within a few hours. Churg has shown that both chrysotile and amphibole fibres retained in the lungs of former miners and millers do not clear much with the years since last exposure. Thus, lung tumours may be caused by that small fraction of the inhaled fibres that are retained in the interstitium below small airway bifurcations where clearance processes are ineffective. By contrast, for mesothelioma, the (low) tumour yields seemed to be highly dependent upon fibre type. Combining the data from various studies by fibre type, the percentage of mesotheliomas was 0.6% for Zimbabwe (Rhodesian) chrysotile, 2.5% for the various amphiboles as a group, and 4.7% for Quebec (Canadian) chrysotile. This difference, together with the fact that Zimbabwe chrysotile has 2 to 3 orders of magnitude less than tremolite than Quebec chrysotile, provides support for the hypothesis that the mesotheliomas that have occurred among chrysotile miners and millers could be largely due to their exposures to tremolite fibres. The chrysotile fibres may be insufficiently biopersistent because if dissolution during translocation from their sites of deposition to sites where more durable fibres can influence the transformation or progression to mesothelioma.
Dust exposure and mortality in chrysotile mining, 1910-76. M. Greenberg. 1994;51(6):431. Comment · Letter PubMed · Publisher · Free full text
Exposure to stainless steel welding fumes and lung cancer: a meta-analysis. B. Sjögren, K.S. Hansen, H. Kjuus, et al. 1994;51(5):335-6. Meta-analysis PubMed · Publisher · Free full text

Abstract

Stainless steel welding is associated with exposure to metals including hexavalent chromium and nickel. This study is a meta-analysis of five studies of stainless steel welders and the occurrence of lung cancer. Asbestos exposure and smoking habits have been taken into account. The calculated pooled relative risk estimate was 1.94 with a 95% confidence interval of 1.28-2.93. This result suggests a causal relation between exposure to stainless steel welding and lung cancer.
Fibrogenic effect of wollastonite compared with asbestos dust and dusts containing quartz. M. Cambelová, A. Juck. 1994;51(5):343-6. PubMed · Publisher · Free full text

Abstract

The distribution of length and diameter and the aspect ratio of crocidolite asbestos, a mineral substitute for asbestos (wollastonite), a manmade mineral fibre (glass wool), and synthetic fibres (polypropylene and polyacrylonitrite) were determined by light microscopy with phase contrast and, for crocidolite, also with transmission electron microscopy. The synthetic organic fibres and manmade mineral fibre used were of a size exceeding that considered respirable. Respirable materials were given to rats by the intratracheal method and after exposure for a standard time interval the main indices of fibrogenic effects--the total hydroxyproline content, the wet weight of the lung, and the total lipid content in the lung--were estimated. For wollastonite there was a significant increase in these variables in comparison with the controls. The fibrogenicity was considerably less than that of crocidolite and quartz.
Findings from high resolution computed tomography of the lung and pleura of symptom free workers exposed to amosite who had normal chest radiographs and pulmonary function tests. S. Neri, A. Antonelli, F. Falaschi, et al. 1994;51(4):239-43. PubMed · Publisher · Free full text

Abstract

The lungs of 50 symptom free workers exposed to amosite and with normal pulmonary function tests were examined by high resolution computed tomography (HRCT). Twenty five had normal standard chest radiographs whereas the other 25 had radiographs interpreted as near normal (International Labour Office profusion score < 0/1 or suspected pleural plaques). In 13 of the workers the results of HRCT were negative; in 22 pleural plaques were found, in five there was only parenchymal involvement, and 10 had both pleural and parenchymal changes. The mean duration of exposure to amosite was significantly longer for the subjects with parenchymal signs than for those with normal parenchyma and for the workers with pleural plaques than for those with normal pleura and lung parenchyma. The prevalence of identified pleural and parenchymal abnormalities in the 50 workers was also significantly higher than in a reference group without exposure to asbestos. It is concluded that HRCT may detect initial lung and pleural involvement in symptom free workers exposed to amosite and the mean duration of exposure is longer for subjects with parenchymal or pleural involvement.
Four cases of mesothelioma among Finnish anthophyllite miners. A. Karjalainen, L.O. Meurman, E. Pukkala. 1994;51(3):212-5. PubMed · Publisher · Free full text

Abstract

Four cases of mesothelioma in a cohort of 999 Finnish anthophyllite miners and millers are described. Three deaths were due to pleural mesothelioma and one to peritoneal mesothelioma among the total of 503 male deaths up to 1991. All four patients with mesothelioma had had long term (13 to 31 years) exposure in anthophyllite mining and milling. The latency time from the onset of employment until diagnosis was 39 to 58 years. All four patients were smokers or ex-smokers and had asbestosis. In three of the cases the pulmonary fibre concentration and fibre type were analysed by transmission electron microscopy. High concentrations (270 to 1100 million fibres/g dry tissue) of anthophyllite fibres were detected. The anthophyllite fibres were thicker and had lower aspect ratios than the values reported for crocidolite fibres retained in the lungs of patients with mesothelioma.
Genetic polymorphism for glutathione-S-transferase mu in asbestos cement workers. K. Jakobsson, A. Rannug, A.K. Alexandrie, et al. 1994;51(12):812-6. PubMed · Publisher · Free full text

Abstract

Objective: To investigate whether a lack of glutathione-S-transferase mu (GSTM1) activity was related to an increased risk for adverse outcome after asbestos exposure.

Methods: A study was made of 78 male former asbestos cement workers, with retrospective cohort data on exposure, radiographical findings, and lung function. Venous blood samples were obtained for the analysis of GSTM1 polymorphism by the polymerase chain reaction technique. Chest x ray films were classified according to the International Labour Organisation (ILO) 1980 classification. Vital capacity (VC) and forced expiratory volume during 1 s (FEV1) were determined. Individual estimates of asbestos exposure were calculated, and expressed as duration of exposure, average exposure intensity, and cumulative dose. Data on smoking were obtained from interviews.

Results: The lung function in the study group was reduced, compared with reference equations. 23% of the workers had small opacities > or = 1/0, 29% circumscribed pleural thickenings, 14% diffuse thickenings, and 12% obliterated costophrenic angles. 54% of the workers were GSTM1 deficient. They were comparable with the other workers in age, follow up time (median 30 years), and duration of exposure (median 18 years), but had a slightly higher cumulated dose (median 18 v 10 fibre-years) than the others. Neither in radiographical changes nor lung function variables were there any differences between the different GSTM1 groups. The findings were similar when smoking habits and estimated asbestos exposure were taken into account.

Conclusions: We could not show that lack of GSTM1 activity was related to an increased risk for radiographical or lung function changes in a group of asbestos cement workers, followed up for a long period after the end of exposure.
Incidence of cancer among anthophyllite asbestos miners in Finland. L.O. Meurman, E. Pukkala, M. Hakama. 1994;51(6):421-5. PubMed · Publisher · Free full text

Abstract

A cohort of 736 male and 167 female workers of two anthophyllite mines in Finland was followed up through the Finnish Cancer Registry for cancer in 1953-91. Compared with the total cancer incidence of the east Finnish population, the men had a raised risk of total cancer (standardised incidence ratio (SIR) 1.7; 95% confidence interval (95% CI) 1.4-1.9), mainly attributable to an excess in lung cancer (SIR 2.8; 95% CI 2.2-3.6). The risk of lung cancer was somewhat higher among workers classified as heavily exposed (SIR 3.2; 95% CI 2.4-4.1) than among those moderately exposed (SIR 2.3; 95% CI 1.5-3.6) and the risk increased with increasing smoking and with increasing time of work with exposure. There were four cases of mesothelioma v 0.1 expected, all in men who smoked and had had a long and heavy asbestos exposure. Among women, a non-significant excess in total cancer (SIR 1.5; 95% CI 0.9-2.4) was found in the subgroup with heavy exposure to asbestos. Anthophyllite asbestos seems to have high potency in the carcinogenesis of lung cancer and low potency in carcinogenesis of mesothelioma in comparison with the other types of asbestos.
Iron associated with asbestos bodies is responsible for the formation of single strand breaks in phi X174 RFI DNA. L.G. Lund, M.G. Williams, R.F. Dodson, et al. 1994;51(3):200-4. PubMed · Publisher · Free full text

Abstract

The ability of amosite cored asbestos bodies isolated from human lungs to catalyse damage to phi X174 RFI DNA in vitro was measured and compared with that of uncoated amosite fibres with a similar distribution of length. Asbestos bodies (5000 bodies) suspended for 30 minutes in 50 mM NaCl containing 0.5 micrograms phi X174 RFI DNA, pH 7.5, did not catalyse detectable amounts of DNA single strand breaks. Addition of the reducing agent ascorbate (1 mM), however, resulted in single strand breaks in 10% of the DNA. Asbestos bodies in the presence of a low molecular weight chelator (1 mM) and ascorbate catalysed the formation of single strand breaks in 21% of the DNA with citrate or 77% with ethylenediamine tetra-acetic acid (EDTA), suggesting that mobilisation of iron may increase damage to DNA. Preincubation for 24 hours with desferrioxamine B, which binds iron (Fe (III)) and renders it redox inactive, completely inhibited the reactivity of asbestos bodies with DNA, strongly suggesting that iron was responsible. Amosite fibres (5000 fibres/reaction), with a similar length distribution to that of the asbestos bodies, did not catalyse detectable amounts of single strand breaks in DNA under identical reaction conditions. The results of the present study strongly suggest that iron deposits on the amosite core asbestos bodies were responsible for the formation of DNA single strand breaks in vitro. Mobilisation of iron by chelators seemed to enhance the reactivity of asbestos bodies with DNA. It has been postulated that the in vivo deposition of the coat material on to fibres may be an attempt by the lung defenses to isolate the fibre from the lung surface and thus offer a protective mechanism from physical irritation. These results suggest, however, that the iron that is deposited on asbestos fibres in vivo may be reactive, potentially increasing the damage to biomolecules, such as DNA, above that of the uncoated fibres.
Malignant mesothelioma: attributable risk of asbestos exposure. R. Spirtas, E.F. Heineman, L. Bernstein, et al. 1994;51(12):804-11. PubMed · Publisher · Free full text

Abstract

Objectives: To evaluate a case-control study of malignant mesothelioma through patterns of exposure to asbestos based upon information from telephone interviews with next of kin.

Methods: Potential cases, identified from medical files and death certificates, included all people diagnosed with malignant mesothelioma and registered during 1975-1980 by the Los Angeles County Cancer Surveillance Program, the New York State Cancer Registry (excluding New York City), and 39 large Veterans Administration hospitals. Cases whose diagnosis was confirmed in a special pathology review as definite or probable mesothelioma (n = 208) were included in the analysis. Controls (n = 533) had died of other causes, excluding cancer, respiratory disease, suicide, or violence. Direct exposure to asbestos was determined from responses to three types of questions: specific queries as to any exposure to asbestos; occupational or non-vocational participation in any of nine specific activities thought to entail exposure to asbestos; and analysis of life-time work histories. Indirect exposures were assessed through residential histories and reported contact with family members exposed to asbestos.

Results: Among men with pleural mesothelioma the attributable risk (AR) for exposure to asbestos was 88% (95% confidence interval (95% CI) 76-95%). For men, the AR of peritoneal cancer was 58% (95% CI 20-89%). For women (both sites combined), the AR was 23% (95% CI 3-72%). The large differences in AR by sex are compatible with the explanations: a lower background incidence rate in women, lower exposure to asbestos, and greater misclassification among women.

Conclusions: Most of the pleural and peritoneal mesotheliomas in the men studied were attributable to exposure to asbestos. The situation in women was less definitive.
Past exposure to asbestos and combustion products and incidence of cancer among Finnish locomotive drivers. P. Nokso-Koivisto, E. Pukkala. 1994;51(5):330-4. PubMed · Publisher · Free full text

Abstract

Locomotive drivers in the steam engine era were exposed to asbestos during their vocational training for two years while training in workshops. Later in their career they had exposure to coal and diesel combustion products. To assess the level of earlier exposure historical working conditions were reconstructed and hygienic conditions were measured. The average exposure to asbestos (mainly anthophylline) fibres > 5 microns was 5.0 fibres/cm3. Incidence of cancer in a cohort of 8391 members of the Finnish Locomotive Drivers' Association, 1953-91, was analysed. The incidence of lung cancer and also total cancer was below the national average, probably due to the low prevalence of smoking among the drivers in the steam engine era. A four-fold risk of mesothelioma was found, most likely caused by exposure to asbestos. Also the observed 1.5-fold incidence of non-melanoma skin cancer and 1.7-fold risk of cancer of the oral cavity and pharynx may be related to occupation.
Pleural mesothelioma and exposure to asbestos: evaluation from work histories and analysis of asbestos bodies in bronchoalveolar lavage fluid or lung tissue in 131 patients. J.C. Pairon, E. Orlowski, Y. Iwatsubo, et al. 1994;51(4):244-9. PubMed · Publisher · Free full text

Abstract

Exposure to asbestos was evaluated in 131 patients with pleural malignant mesothelioma in the Paris area between 1986 and 1992 using data from a detailed specific questionnaire and light microscopy analysis of the retention of asbestos bodies in bronchoalveolar lavage fluid or lung tissue. Probable or definite exposure to significant levels of asbestos dust was identified in only 48 (36.6%) subjects, and significant asbestos body counts (above 1 asbestos body/ml in bronchoalveolar lavage fluid or 1000 asbestos bodies/g of dry lung tissue) were found in only 45 (34.3%) subjects. Overall 50 subjects had experienced exposure to only low levels of asbestos or no exposure at all and showed no significant retention of asbestos bodies in the biological sample analysed. Previous studies have shown that light microscopy may be useful in the identification of subjects with previous exposure to asbestos. In this study, apart from cases with obvious exposure to asbestos, a large group of subjects seemed to have a history of exposure or lung retention of asbestos bodies suggestive of very low levels of cumulative exposure, similar to those described in the general population.
Pleural plaques and exposure to mineral fibres in a male urban necropsy population. A. Karjalainen, P.J. Karhunen, K. Lalu, et al. 1994;51(7):456-60. PubMed · Publisher · Free full text

Abstract

Objectives: The study aimed to evaluate the risk of pleural plaques according to the degree of past exposure to asbestos, type of amphibole asbestos, and smoking, as well as to estimate the aetiologic fraction of asbestos as a cause of plaques among urban men.

Methods: The occurrence and extent of pleural plaques were recorded at necropsies of 288 urban men aged 33 to 69 years. The pulmonary concentration of asbestos and other mineral fibres was analysed with scanning electron microscopy. The probability of past exposure was estimated from the last occupation.

Results: Pleural plaques were detected in 58% of the cases and their frequency increased with age, probability of past occupational exposure to asbestos, pulmonary concentration of asbestos fibres, and smoking. The risk of both moderate and widespread plaques was raised among asbestos exposed cases, and the risk estimates were higher for widespread plaques than for moderate plaques. The age adjusted risk was higher for high concentrations of crocidolite/amosite fibres than for anthophyllite fibres. The aetiologic fraction of pulmonary concentration of asbestos fibres exceeding 0.1 million fibres/g was 43% for widespread plaques and 24% for all plaques. The median pulmonary concentrations of asbestos fibres were about threefold greater among cases with widespread plaques than among those without plaques. No increased risk of pleural plaques was associated with raised total concentrations of non-asbestos fibres.

Conclusion: The occurrence of pleural plaques correlated closely with past exposure to asbestos. The risk was dependent on the intensity of exposure. Due to methodological difficulties in detecting past exposures to chrysotile and such low exposures that may still pose a risk of plaques, the aetiologic fractions calculated in the study probably underestimate the role of asbestos.
Relation between lung asbestos fibre burden and exposure indices based on job history. K. Takahashi, B.W. Case, A. Dufresne, et al. 1994;51(7):461-9. PubMed · Publisher · Free full text

Abstract

Lung asbestos burden was compared with exposure indices derived from job history interviews in 42 male subjects originating from the Montréal Case-Control Study project, 12 of whom had documented asbestos exposed job histories. Job interview data consisting of a chronological timetable of job histories were translated into detailed exposure indices by an expert group of hygienists and chemists. Total and individual asbestos fibre type concentrations were quantified by transmission electron microscopy with fibre identification by energy dispersive chi ray spectrometry after deparaffinisation of tissue blocks and low temperature plasma ashing. Geometric mean or median asbestos content was higher in subjects with an asbestos exposed job history than those without for retained dose of amosite, total commercial amphiboles, and total asbestos fibre. Except for crocidolite fibre diameter, which was significantly less in the lungs of exposed workers, no consistent differences were found in measurements of fibre dimension for any fibre type. Subgroups of subjects exposed to silica, metals, or smokers and non-smokers without significant occupational exposure showed varying patterns of lung asbestos fibre type deficit compared with the asbestos exposed subgroup. There was an overall trend for higher lung asbestos content proportional to higher exposure indices for asbestos representing concentration, frequency, and reliability. These exposure indices as well as duration of exposure (in years) were independent predictors of total asbestos content in regression analyses when combined in a model with age. Stepwise regression indicated that exposure concentration was the most important variable, explaining 32% of the total variation in total asbestos content. Smoking, whether expressed in ever or never smoked dichotomy or in smoked-years, had no relation to lung asbestos content in this model.
Retention patterns of asbestos fibres in lung tissue among asbestos cement workers. M. Albin, F.D. Pooley, U. Strömberg, et al. 1994;51(3):205-11. PubMed · Publisher · Free full text

Abstract

Retention patterns in lung tissue (determined by transmission electron microscopy and energy dispersive spectrometry) of chrysotile, tremolite, and crocidolite fibres were analysed in 69 dead asbestos cement workers and 96 referents. There was an accumulation of tremolite with time of employment. Among workers who died within three years of the end of exposure, the 13 with high tremolite concentrations had a significantly longer duration of exposure than seven in a low to intermediate category (medians 32 v 20 years; p = 0.018, one sided). Crocidolite showed similar patterns of accumulation. In workers who died more than three years after the end of exposure, there were no correlations between concentrations of amphibole fibres and time between the end of exposure and death. Chrysotile concentrations among workers who died shortly after the end of exposure were higher than among the referents (median difference in concentrations 13 million fibres (f)/g dry weight; p = 0.033, one sided). No quantitative differences in exposure (duration or intensity) could be shown between workers with high and low to intermediate concentrations. Interestingly, all seven workers who had had a high intensity at the end of exposure (> 2.5 f/ml), had low to intermediate chrysotile concentrations at death, whereas those with low exposure were evenly distributed (31 subjects in both concentration categories); hence, there was a dependence between last intensity of exposure and chrysotile concentration (p = 0.014). Among 14 workers with a high average intensity of exposure, both those (n = 5) with high tissue concentrations of chrysotile and those (n = 10) with high tissue concentrations of tremolite fibres had more pronounced fibrosis than those with low to intermediate concentrations (median fibrosis grades for chrysotile: 2 v 1, p = 0.021; for tremolite: 2 v 0.5, p = 0.012). Additionally, workers who died shortly after the end of exposure with high concentrations of chrysotile and crocidolite had smoked more than those with low intermediate concentrations (medians for chrysotile 35 v 15 pack-years, p = 0.030; for crocidolite 37 v 15 pack-years, p = 0.012). The present data indicate that chrysotile has a relatively rapid turnover in human lungs, whereas the amphiboles, tremolite and crocidolite, have a slower turnover. Further, chrysotile retention may be dependent on dose rate. Chrysotile and crocidolite deposition and retention may be increased by tobacco smoking; chrysotile and tremolite by fibrosis.
Scientific objectivity and the chrysotile controversy. B.I. Castleman. 1994;51(6):431. Comment · Letter PubMed · Publisher · Free full text
Study of occupational lung cancer in asbestos factories in China. R.W. Morgan, K.E. Zhao. 1994;51(10):719. Comment · Letter PubMed · Publisher · Free full text

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