British Journal of Industrial Medicine

About the journal

Publisher: British Medical Assn
Published: 1944–1993, England
Language: English
ISSN: 0007-1072 (print)
Continued by: Occupational and Environmental Medicine
Its record in the NLM Catalog

1990s

A case-control study of malignant and non-malignant respiratory disease among employees of a fiberglass manufacturing facility. II. Exposure assessment. L. Chiazze, D.K. Watkins, C. Fryar, et al. 1993;50(8):717-25. PubMed · Publisher · Free full text

Abstract

A case-control study of malignant and non-malignant respiratory disease among employees of the Owens-Corning Fiberglas Corporation's Newark, Ohio plant was undertaken. The aim was to determine the extent to which exposures to substances in the Newark plant environment, to non-workplace factors, or to a combination may play a part in the risk of mortality from respiratory disease among workers in this plant. A historical environmental reconstruction of the plant was undertaken to characterise the exposure profile for workers in this plant from its beginnings in 1934 to the end of 1987. The exposure profile provided estimates of cumulative exposure to respirable fibres, fine fibres, asbestos, talc, formaldehyde, silica, and asphalt fumes. Employment histories from Owens-Corning Fiberglas provided information on employment characteristics (duration of employment, year of hire, age at first hire) and an interview survey obtained information on demographic characteristics (birthdate, race, education, marital state, parent's ethnic background, and place of birth), lifetime residence, occupational and smoking histories, hobbies, and personal and family medical history. Matched, unadjusted odds ratios (ORs) were used to assess the association between lung cancer or non-malignant respiratory disease and the cumulative exposure history, demographic characteristics, and employment variables. Only the smoking variables and employment characteristics (year of hire and age at first hire) were statistically significant for lung cancer. For non-malignant respiratory disease, only the smoking variables were statistically significant in the univariate analysis. Of the variables entered into a conditional logistic regression model for lung cancer, only smoking (smoked for six months or more v never smoked: OR = 26.17, 95% confidence interval (95% CI) 3.316-206.5) and age at first hire (35 and over v less than 35: OR = 0.244, 95% CI 0.083-0.717) were statistically significant. There were, however, increased ORs for year of employment (first hired before 1945 v first hire after 1945: OR = 1.944, 95% CI 0.850-4.445), talc (cumulative exposure >1000 fibres/ml days v never exposed: OR = 1.355, 95% CI 0.407-5.515), and asphalt fumes (cumulative exposure >0.01 mg/m(3) days v never exposed: OR 1.131, 95% CI 0.468-2.730). For non-malignant respiratory disease, only the smoking variable was significant in the conditional logistic regression analysis (OR = 2.637, 95% CI 1.146-6.069). There were raised ORs for the higher cumulative exposure categories for respirable fibres, asbestos, silica, and asphalt fumes. For both silica and asphalt fumes, ORs were more than double the reference groups for all exposure categories. A limited number of subjects were exposed to fine fibres. The scarcity of cases and controls limits the extent to which analyses for fine fibre may be carried out. Within those limitations, among those who had worked with fine fibre, the unadjusted, unmatched OR for lung cancer was (1.0 (95% CI 0.229-4.373) and for non-malignant respiratory disease, the OR was 1.5 (95% CI 0.336-6.702). The unadjusted OR for lung cancer for exposure to fine fibre was consistent with that for all respirable fibre and does not suggest an association. For non-malignant respiratory disease, the unadjusted OR for fine fibre was opposite in direction from that for all respirable fibres. Within the limitations of the available data on fibre, there is o suggestion that exposure to fine fibre has resulted in an increase in risk of lung cancer. The increased OR for non-malignant respiratory disease is inconclusive. The results of this population, in this place and time, neither respirable fibres nor any of the substances investigated as part of the plant environment are statistically significant factors for lung cancer risk although there are increased ORs for exposure to talc and asphalt fumes. Smoking is the most important factors in risk for lung cancer in this population. The situation is less clear for non-malignant respiratory disease. Unlike lung cancer, non-malignant respiratory represents a constellation of outcomes and not a single well defined end point. Although smoking was the only statistically significant factor for non-malignant respiratory disease in this analysis, the ORs for respirable fibres, asbestos, silica, and asphalt fumes were greater than unity for the highest exposure categories. Although the raised ORs for these substances may represent the results of a random process, they may be suggestive of an increased risk and require further investigation.
A cohort study on mortality among wives of workers in the asbestos cement industry in Casale Monferrato, Italy. C. Magnani, B. Terracini, C. Ivaldi, et al. 1993;50(9):779-84. PubMed · Publisher · Free full text

Abstract

The study investigates mortality from cancer and other diseases in a cohort of wives of asbestos cement workers in Casale Monferrato (northwest Italy). After the exclusion of women with an occupational record in the asbestos cement industry, the cohort comprised 1964 women. Their domestic exposure was estimated according to their husbands' periods of employment in the plant: 1740 had a period of domestic exposure whereas the remaining 224 married an asbestos cement worker only after he definitely stopped his activity in the asbestos cement plant; these have, therefore, been considered as unexposed. The cohort of wives was constructed entirely through official records in the town offices and is both exhaustive and unaffected by recall bias. At the end of follow up (1988) 1669 women were alive, 270 were dead and 25 (1.2%) were untraced. Main mortality analyses were only up to age 79 to reduce the misclassification of causes of death. Expected mortality was based on local rates. Mortality analyses were limited to the period 1965-88 due to the availability of local rates: in that period 210 deaths occurred among women with domestic exposure v 229.1 expected. There were four deaths from pleural tumours (one diagnosed as mesothelioma at necropsis) and six from lung cancer v. 0.5 and 4.0 expected respectively. Two further cases of mesothelioma were diagnosed by histological examination after the end of follow up. None of the three wives with histologically diagnosed mesothelioma had been engaged in industrial activities. Corresponding information for the other three cases could not be traced.
A mortality study among mild steel and stainless steel welders. J.J. Moulin, P. Wild, J.M. Haguenoer, et al. 1993;50(3):234-43. PubMed · Publisher · Free full text

Abstract

A mortality study was carried out in conjunction with the European mortality study among welders coordinated by the International Agency for Research on Cancer (IARC). The study was aimed at assessing risks for lung cancer in relation to exposure to asbestos, welding fumes containing chromium and nickel, and tobacco smoke. The study included a cohort of 2721 welders and an internal comparison group of 6683 manual workers employed in 13 factories in France. The mortality of the two cohorts was studied from 1975 to 1988 by the historical prospective method. Job histories of welders were traced including welding processes used, metals welded, and proportion of worktime spent in welding. Data on smoking habits were collected from medical records. The observed number of deaths were compared with those expected (standardised mortality ratio (SMR)) based on national rates with adjustments for age, sex, and calendar time. The smoking habits of 87% of the whole study population were known. The distribution of welders and controls according to smoking was not statistically different. The overall mortality was slightly higher for welders (SMR = 1.02, 95% confidence interval (95% CI) 0.89-1.18) than for controls (SMR = 0.91, 95% CI 0.84-0.99). For lung cancer, the SMR was 1.24 (95% CI 0.75-1.94) for welders, whereas the corresponding value was lower for controls (SMR = 0.94, 95% CI 0.68-1.26). The SMR for lung cancer was 1.59 among non-shipyard mild steel welders (95% CI 0.73-3.02). This contrasted with the results for all stainless steel welders (SMR = 0.92, 95% CI 0.19-2.69), and for stainless steel welders predominantly exposed to chromium VI (SMR = 1.03, 95% CI 0.12-3.71). Moreover, SMRs for lung cancer for mild steel welders tended to increase with duration of exposure and time since first exposure, leading to significant excesses for duration > or = 20 years and latency > or = 20 years. Such a pattern was not found for stainless steel welders.
Absence of amosite asbestos in airway mucosa of non-smoking long term workers with occupational exposure to asbestos. A. Churg, B. Stevens. 1993;50(4):355-9. PubMed · Publisher · Free full text

Abstract

There is considerable experimental evidence that asbestos fibres are taken up by epithelial cells, and that uptake of fibres is associated with various deleterious, particularly mutagenic, effects. It is not known, however, if asbestos fibres are taken up by human bronchial epithelial cells in vivo. To investigate this question, the amosite asbestos content of the mucosa of seven different airways and four parenchymal sites supplied by these airways in six necropsy lungs from heavily exposed never-smoking long term shipyard and insulation workers without asbestosis was examined. Amosite asbestos was readily found in moderately high concentration in all parenchymal samples, but 33 of 40 airway samples that could be evaluated showed no amosite fibres. The seven positive airways had fibre concentrations that were always much lower than the parenchymal concentrations, and these very few fibres may have been contaminants from the parenchyma. These data suggest that, at least in non-smokers, amosite asbestos either does not penetrate into or does not accumulate in human airway mucosa. These findings also call into question the idea that asbestos acts as a direct airway carcinogen in humans.
Analysis of ferruginous bodies in bronchoalveolar lavage from foundry workers. R.F. Dodson, M. O'Sullivan, C.J. Corn, et al. 1993;50(11):1032-8. PubMed · Publisher · Free full text

Abstract

Classical ferruginous bodies in tissue samples are considered to be markers of past exposure to asbestos. Recent studies have shown that the presence of ferruginous bodies in bronchoalveolar lavage (BAL) fluid correlates with past exposure to asbestos and offers a more sensitive reference than occupational history. Lavage samples from five subjects who had worked in foundries were evaluated by light microscopy for the presence of ferruginous bodies and by transmission electron microscopy for both characterisation of the uncoated fibre burden and analysis of the cores of the ferruginous bodies. All samples at lower magnification (light microscopy (200 x)) contained ferruginous bodies that were externally consistent with asbestos bodies. At higher magnification (400 x), a separate population from this group could be identified by the presence of a thin black ribbon. Transmission electron microscopy of the core materials of ferruginous bodies and comparable uncoated particulates supported the reliability of higher magnification light microscopy for distinguishing most of those non-asbestos cores; however, a population of transparent non-asbestos cored ferruginous bodies were also shown to exist.
Asbestos and cancer: history and public policy. M. Greenberg. 1993;50(1):95. Comment · Letter PubMed · Publisher · Free full text
Asbestos and cancer: history and public policy. M.P. Weller. 1993;50(7):671. Historical article · Letter PubMed · Publisher · Free full text
Chrysotile asbestos revisited. J. Dunnigan. 1993;50(9):862-3. Letter PubMed · Publisher · Free full text
Computed tomography in the early detection of asbestosis. R. Bégin, G. Ostiguy, R. Filion, et al. 1993;50(8):689-98. PubMed · Publisher · Free full text

Abstract

Computed tomography (CT; both conventional (CCT) and high resolution (HRCT)) scans of the thorax were evaluated to detect early asbestosis in 61 subjects exposed to asbestos dust in Québec for an average of 22(3) years and in five controls. The study was limited to consecutive cases with chest radiographs of the International Labour Organisation categories 0 or 1 determined independently. All subjects had a standard high kilovoltage posteroanterior and lateral chest radiograph, a set of 10-15 1 cm collimation CCT scans and a set of three to five 2 mm collimation HRCT scans in the upper, middle, and lower lung fields. Five experienced readers independently read each chest radiograph and sets of CT scans. On the basis of three to five readers agreeing for small opacities of the lung parenchyma, 12/46 (26%) negative chest radiographs were positive on CT scans, but 6/18 (33%) positive chest radiographs were negative on CT scan. On the basis of four to five readers agreeing on a chest radiograph, 36/66 (54%) subjects were normal (group A), 17/66 (26%) were indeterminate (group B), and 13/66 (20%) were abnormal (group C). By the combined readings of CCT and HRCT, 4/31 (13%) asbestos exposed subjects of group A were abnormal (p < 0.001), 6/17 (35%) of group B were abnormal, and in group C, 1/13 (8%) was normal, 2/13 were indeterminate, and 10/13 (77%) were abnormal. Separate readings of CCT and HRCT on distinct films in 14 subjects showed that all cases of asbestosis were abnormal on both CCT and HRCT. Inter-reader analyses by kappa statistics showed significantly better agreement for the readings of CT than the chest radiographs (p < 0.001), and for the reading of CCT than HRCT (p < 0.01). Thus CT scans of the thorax identifies significantly more irregular opacities consistent with the diagnosis of asbestosis than the chest radiograph (20 cases on CT scans v 13 on chest radiographs when four to five readers agreed, 13% of asbestos exposed subjects with normal chest radiographs or 21% of asbestos exposed subjects with normal or near normal chest radiographs. It decreased the number of indeterminate cases significantly from 17 on chest radiographs to 13 on CT scans. All cases of asbestosis detected only on CT scans were similarly seen on CCT and HRCT and did not have significant changes in lung function. The CT scans significantly reduced the inter-reader variability, despite the absence of ILO type reference films for these scans.
Dust exposure and mortality in chrysotile mining, 1910-75. 1980. J.C. McDonald, F.D. Liddell, G.W. Gibbs, et al. 1993;50(12):1058-72. Historical article PubMed · Free full text

Abstract

We report a further follow-up of a birth cohort of 11 379 workers exposed to chrysotile. The cohort consisted of all 10 939 men and 440 women, born 1891-1920, who had worked for at least a month in the mines and mills of Asbestos and Thetford Mines in Quebec. For all subjects, length of service and estimates of accumulated dust exposure were obtained, with a smoking history for the vast majority. Three methods of analysis, two based on the "man-years" method, the other a "case-and-multiple-controls" approach, gave results consistent with one another and with previous analyses. By the end of 1975, 4463 men and 84 women had died. Among men, the overall excess mortality, 1926-75, was 2% at Asbestos and 10% at Thetford Mines, much the dustier region. The women, mostly employed at Asbestos, had a standardised mortality ratio (SMR) (all causes, 1936-75) of 0.90. Analysis of deaths 20 years or more after first employment showed that in men with short service (less than five years) there was no discernible correlation with dust exposure. Among men employed at least 20 years, there were clear excesses in those exposed to the heaviest dust concentrations. Reanalysis in terms of exposure to age 45 showed definite and consistent trends for SMRs for total mortality, for lung cancer, and for pneumoconiosis to be higher the heavier the exposure. The response to increasing dose was effectively linear for lung cancer and for pneumoconiosis. Lung cancer deaths occurred in non-smokers, and showed a greater increase of incidence with increasing exposure than did lung cancer in smokers, but there was insufficient evidence to distinguish between multiplicative and additive risk models. There were no excess deaths from laryngeal cancer, but a clear association with smoking. Ten men and one woman died from pleural mesothelioma. If the only subjects studied had been the 1904 men with at least 20 years' employment in the lower dust concentrations, averaging 6.6 million particles per cubic foot (or about 20 fibres/cc), excess mortality would not have been considered statistically significant, except for pneumoconiosis. The inability of such a large epidemiological survey to detect increased risk at what, today, are considered unacceptable dust concentrations, and the consequent importance of exposure-response models are therefore emphasised.

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Effect of smoking on pleural thickening in asbestos workers. E. Yano, K. Tanaka, M. Funaki, et al. 1993;50(10):898-901. PubMed · Publisher · Free full text

Abstract

It is well known that an interaction exists between smoking and exposure to asbestos in the occurrence of lung cancer, whereas occurrence of malignant mesothelioma has not been related to smoking. In the case of pleural thickening related to asbestos, there is a disagreement in previous studies as to the effect of smoking. This could be because the diagnosis of pleural changes has a subjective element. Taking this into account, in the present work the maximum width of the pleura was used as an index of pleural changes. Study subjects were 134 asbestos workers of a brake manufacturing company who had received medical checks in 1978 and in 1990. The maximum width of the pleura on the chest x ray films of the workers was measured by two examiners who did not know the year of examination or smoking state of the worker. A general linear model was applied to analyse the effects of smoking, the year of examination, age, and duration of exposure to asbestos. The difference between maximum widths measured in 1978 and 1990 suggested chronological progression. The increase in width during the 12 years, however, did not differ significantly between smokers and nonsmokers. This suggests that smoking does not significantly increase pleural thickening in asbestos workers.
Effects of phosphorylation of chrysotile on pleuropulmonary fibrogenicity and carcinogenicity. H. Daniel, A. Wastiaux, P. Sébastien, et al. 1993;50(2):167-71. PubMed · Publisher · Free full text

Abstract

As well as fibre size, fibre chemistry is a determinant of toxicity of mineral fibres. On these grounds, a few years ago, the asbestos industry in Québec developed a process to modify the surface chemistry of chrysotile asbestos by fixing phosphorous atoms. The pleuropulmonary fibrogenicity and carcinogenicity of the native and surface treated chrysotile, called chrysophosphate, were tested. Both products initiated similar pulmonary fibrogenicity in rats exposed by inhalation and sheep exposed by injection in the tracheal lobe. Tumour production in rats after long term inhalation or intrapleural injection was not different between chrysotile and chrysophosphate. These findings clearly show that modification of the phosphate surface of chrysotile fibres does not appear to alter the pleuropulmonary activities of the mineral, thus arguing against the earlier contention of less biological activity for chrysophosphate, a contention essentially based upon results of in vitro tests. This study strongly argues for in vivo testing of new fibrous materials before making definite conclusions about their biological activities.
Incidence of cancer among welders of mild steel and other shipyard workers. T.E. Danielsen, S. Langård, A. Andersen, et al. 1993;50(12):1097-103. PubMed · Publisher · Free full text

Abstract

The incidence of cancer among 4571 shipyard workers with first employment between 1940 and 1979, including 623 welders of mild steel, was investigated in a historical cohort study. The loss to follow up was 1.1%. The total number of deaths was 1078 (974.5 expected) and there were 408 cases of cancer v 361.3 expected. Sixty five cases of lung cancer were found v 46.3 expected based on the national rates for males. Four pleural mesotheliomas had occurred (1.2 expected), none among the welders. An excess of lung cancers was found among the welders (nine cases v 3.6 expected). There were six cases of lung cancer v 1.6 expected in a high exposure group of 255 welders. A survey of the smoking habits as of 1984 indicated 10%-20% more daily smokers among the shipyard production workers than among Norwegian males. Exposure to smoking and asbestos were confounding variables in this study.
Incidence of cancer and mortality among workers exposed to mercury vapour in the Norwegian chloralkali industry. D.G. Ellingsen, A. Andersen, H.P. Nordhagen, et al. 1993;50(10):875-80. PubMed · Publisher · Free full text

Abstract

Incidence of cancer and mortality were studied among 674 men exposed to mercury vapour for more than one year at two chloralkali plants. Mercury excretion in urine had been monitored among the workers at the two plants since 1948 and 1949. An individual cumulative urinary mercury dose was calculated, based on about 20,000 urinary mercury measurements. The incidence of cancer and the mortality were followed up from 1953 to 1989 and 1953 to 1988 respectively. The general Norwegian male population served as a reference population. There was a lung cancer excess of borderline significance (standardised incidence ratio = 1.66, 95% confidence interval = 1.00-2.59). The introduction of a 10 year latent period before developing lung cancer did not increase the incidence ratio. The excess may be partly explained by the smoking habits in the cohort or possibly by exposure to asbestos. No excess of cancer was found in the target organs for mercury toxicity--namely, the kidney and the nervous system. No significant excess mortality was found for nephritis and nephrosis or nonmalignant diseases of the nervous system.
Incidence of lung cancer by histological type among asbestos cement workers in Denmark. B. Järrholm. 1993;50(8):767. Comment · Letter PubMed · Free full text
Incidence of lung cancer by histological type among asbestos cement workers in Denmark. E. Raffn, E. Lynge, B. Korsgaard. 1993;50(1):85-9. PubMed · Publisher · Free full text

Abstract

Objective: A significant twofold increased risk of lung cancer was found among 8000 men employed in the Danish asbestos cement industry between 1928 and 1984. The histological pattern of 104 lung cancer cases was studied with the aim of evaluating a relation between specific morphological types, duration of employment, and time since first employment.

Methods: Age, sex, and calendar time specific incidence of morphological subtypes of lung cancer (adenocarcinoma, squamous cell carcinoma, anaplastic carcinoma, and unspecified malignant tumour) for all Danish men were computed from 1943 to 1984, from data routinely collected by the Danish Cancer Registry. Person-years of observation were counted from 15 years after the date of first employment until date of diagnosis of cancer, death, emigration, or the end of follow up on 31 December 1984. Expected numbers of cases were computed by applying person-years at risk to the appropriate incidence rates. Observed numbers were distributed accordingly and the relative risk calculated.

Results: The relative risk for adenocarcinoma was 3.31 (observed (O) 24, expected (E) 7.26), for squamous cell carcinoma 1.67 (O, 37, E, 22.12), for anaplastic carcinoma 1.58 (O, 23, E, 14.53), and for unspecified malignant tumour 1.57 (O, 18, E, 11.46). An increased risk by duration of employment and time since first employment was most pronounced for adenocarcinoma.

Conclusion: The link between adenocarcinoma and asbestos was confirmed in this, the first study of risk of lung cancer by histological category based on incident cancer cases for a whole population during a 50 year period.
Lung function in insulation workers. J. Clausen, B. Netterstrøm, C. Wolff. 1993;50(3):252-6. PubMed · Publisher · Free full text

Abstract

To evaluate the effects of working with modern insulation materials (rock and glass wool), the members of the Copenhagen Union of Insulation Workers were invited to participate in a study based on a health examination that included lung function tests. Three hundred and forty men (74%) agreed to participate, and 166 bus drivers served as the control group. Age distribution, height, and smoking habits were similar in the two groups. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were used as tests for lung function. There were no differences in FVC between the study and control groups, but the insulation workers had significantly lower values of FEV1 (mean 2.51) compared with the controls (mean 3.4 1), independent of smoking habits. Six years before the present study, 114 of the insulation workers participated in a similar study, and eight years after the initial study, the lung function of 59 of the bus drivers was tested. The decline in FVC in insulation workers who smoked was significantly higher (7.7 cl/year) than in bus drivers who smoked (3.1 cl/year); the decline in FEV1 was significantly higher in insulation workers independent of smoking habits (17.0 cl/year v 2.9 cl/year). Self assessed former exposure to asbestos was not associated with lung function in insulation workers. The study concludes that working with modern insulation materials is associated with increased risk of developing obstructive lung disease.
Lymphocyte B and T cell subsets in peripheral blood from patients with asbestosis. L. Peng, X. Wang. 1993;50(2):183-4. PubMed · Publisher · Free full text

Abstract

Peripheral blood lymphocytes were analysed by indirect staphylococcus protein A (SPA) rosette assay using monoclonal antibodies that identify B cells, total T cells (OKT3+), helper-inducer T cells (OKT4+), and suppressor-cytotoxic T cells (OKT8+). The purpose of this investigation was to determine the characteristics of lymphocyte B and T subsets in peripheral blood, and the relation of the changes to radiographic abnormalities in workers exposed to asbestos.
Lymphocyte subsets in subjects exposed to asbestos: changes in circulating natural killer cells. P.J. Borm, P.F. Schins. 1993;50(6):575. Comment · Letter PubMed · Publisher · Free full text
Mechanisms of asbestos carcinogenesis and toxicity: the amphibole hypothesis revisited. B.T. Mossman. 1993;50(8):673-6. Editorial PubMed · Publisher · Free full text

Summary

In this editorial the author reviewed experimental evidence on how asbestos causes cancer and cell injury, in light of the "amphibole hypothesis". The editorial noted that mesothelioma incidence varies by fibre type and is highest with crocidolite exposure. It also noted debate over whether mesotheliomas in Quebec chrysotile miners and millers can be attributed to tremolite. Under the hypothesis, fibre durability over latency periods averaging 35 to 40 years is an important but not exclusive factor. The author summarised findings on chromosomal changes in human mesotheliomas, including losses of chromosomes 4, 22 and 9p. Searches for ras and myc mutations were negative, and p53 or retinoblastoma alterations were few; one study found p53 abnormalities in only three of 20 mesothelioma cell lines. Asbestos was not mutagenic in the Ames test, but a human-hamster hybrid cell assay detected large multilocus lesions from chrysotile and crocidolite. Evidence was reviewed that active oxygen species, produced by phagocytic cells in response to long fibres or catalysed by iron on fibre surfaces, mediate asbestos effects. Crocidolite contains about 36% iron by weight, compared with 2%-3% in some chrysotile samples. Work from the author's laboratory showed persistent, dose dependent induction of c-fos and c-jun in mesothelial cells, most pronounced with crocidolite. The author proposed a hypothetical model in which fibre durability, persistence and iron content explain crocidolite's greater pathogenicity. Chrysotile dissolves in the lung and may not persist long enough, whereas minimal biodegradation over rodents' two to three year lifespan may explain similar tumour incidence across fibre types in rodent models.

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.
Mesothelioma of pleura and peritoneum following exposure to asbestos in the London area. 1965. M.L. Newhouse, H. Thompson. 1993;50(9):769-78. Historical article PubMed · Free full text

Abstract

A series of 83 patients from the London Hospital with a diagnosis of mesothelioma confirmed by necropsy or biopsy has been studied for possible exposure to asbestos. The series consisted of 41 men and 42 women; 27 of the patients had peritoneal and 56 pleural tumours. The earliest death recorded was in 1917, but only 10 of the series died before 1950 and 40 (48%) between 1960 and 1964.

In 76 of the series full occupational and residential histories were obtained. Forty (52.6%) gave a history of occupational or domestic (living in the same house as an asbestos worker) exposure to asbestos compared with nine (11.8%) out of 76 patients from the same hospital suffering from other diseases (P < 0.001). None of the 17 suspected cases of mesothelioma, rejected on pathological grounds, was found to have had any exposure to asbestos. There was also evidence that neighbourhood exposures may be important. Among those with no evidence of occupational or domestic exposures, 30.6% of the mesothelioma patients and 7.6% of the in-patients with other diseases lived within half a mile of an asbestos factory (P < 0.01). Out of the 31 patients with occupational exposures only 10 were in jobs scheduled under the Asbestos Regulations of 1931. The interval between first exposure and the development of the terminal illness of mesothelioma ranged between 16 and 55 years.

In 47 patients in the mesothelioma series, lung tissue or sputum was available for examination. In 30 (62.5%), either asbestosis or asbestos bodies were present.

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Mortality from lung cancer in asbestos workers 1955. R. Doll. 1993;50(6):485-90. Historical article PubMed · Publisher · Free full text

Abstract

The cause of death, as determined at necropsy, is reported for 105 persons who had been employed at one asbestos works. Lung cancer was found in 18 instances, 15 times in association with asbestosis. All the subjects in whom both conditions were found had started employment in the industry before 1923 and had worked in the industry at least nine years before the regulations for the control of dust had become effective. One hundred and thirteen men who had worked for at least 20 years in places where they were liable to be exposed to asbestos dust were followed up and the mortality among them compared with that which would have been expected on the basis of the mortality experience of the whole male population. Thirty-nine deaths occurred in the group whereas 15.4 were expected. The excess was entirely due to excess deaths from lung cancer (11 against 0.8 expected) and from other respiratory and cardiovascular diseases (22 against 7.6 expected). All the cases of lung cancer were confirmed histologically and all were associated with the presence of asbestosis. From the data it can be concluded that lung cancer was a specific industrial hazard of certain asbestos workers and that the average risk among men employed for 20 or more years has been of the order of 10 times that experienced by the general population. The risk has become progressively less as the duration of employment under the old dusty conditions has decreased.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.
Occupational exposure to dust and lung disease among sheet metal workers. K.L. Hunting, L.S. Welch. 1993;50(5):432-42. PubMed · Publisher · Free full text

Abstract

A previous large medical survey of active and retired sheet metal workers with 20 or more years in the trade indicated an unexpectedly high prevalence of obstructive pulmonary disease among both smokers and non-smokers. This study utilised interviews with a cross section of the previously surveyed group to explore occupational risk factors for lung disease. Four hundred and seven workers were selected from the previously surveyed group on the basis of their potential for exposure to fibreglass and asbestos. Selection was independent of health state, and excluded welders. A detailed history of occupational exposure was obtained by telephone interview for 333 of these workers. Exposure data were analysed in relation to previously collected data on chronic bronchitis, obstructive lung disease, and personal characteristics. Assessment of the effects of exposure to fibreglass as distinct from the effects of exposure to asbestos has been difficult in previous studies of construction workers. The experienced workers studied here have performed a diversity of jobs involving exposure to many different types of materials, and this enabled exposure to each dust to be evaluated separately. The risk of chronic bronchitis increased sharply by pack-years of cigarettes smoked; current smokers had a double risk compared with those who had never smoked or had stopped smoking. The occurrence of chronic bronchitis also increased with increasing duration of exposure to asbestos. Workers with a history of high intensity exposure to fibreglass had a more than doubled risk of chronic bronchitis. Obstructive lung disease, defined by results of pulmonary function tests at the medical survey, was also related to both smoking and occupational risk factors. Number of pack years smoked was the strongest predictor of obstructive lung disease. Duration of direct and indirect exposure to welding fume was also a positive predictor of obstructive lung disease. Duration of exposure to asbestos was significantly associated with obstructive lung disease but the dose-response relation was inconsistent, especially for those with higher pack-years of smoking exposure. Exposure to fibreglass was not a risk factor for obstructive lung disease.
Production of interleukin 1 by rat pleural leucocytes in culture after intratracheal instillation of crocidolite asbestos. X.Y. Li, D. Lamb, K. Donaldson. 1993;50(1):90-4. PubMed · Publisher · Free full text

Abstract

This study was undertaken to investigate the production of interleukin 1 (IL-1) by pleural leucocytes in culture and to evaluate the influence of intratracheal instillation of crocidolite asbestos on this production. Normal pleural leucocytes spontaneously released IL-1 in culture and stimulation with lipopolysaccharide (LPS) dramatically increased production. Intratracheal instillation with crocidolite asbestos induced recruitment of pleural leucocytes in the longer term and changed IL-1 production by the leucocytes. Reduced production of IL-1 was found by one day after instillation of asbestos and this was correlated with the dose of asbestos. With increasing time after instillation, however, release of IL-1 by pleural leucocytes gradually recovered to normal until, one month after asbestos injection, the leucocytes produced augmented IL-1 in culture compared with control pleural leucocytes. Our data show that pleural leucocytes possess the potential to produce IL-1 in vitro and this capability is altered by intratracheal instillation of crocidolite asbestos. This may be relevant to development of pleural diseases associated with inhalation of asbestos.
Radiographic abnormalities and mortality in subjects with exposure to crocidolite. N.H. de Klerk, A.W. Musk, W.O. Cookson, et al. 1993;50(10):902-6. PubMed · Publisher · Free full text

Abstract

Plain chest radiographs from a one in six random sample of the workforce of the asbestos industry at Wittenoom, Western Australia between 1943 and 1966 have been classified for degree of profusion and pleural thickening by two independent observers according to the 1980 UICC-ILO Classification of Radiographs for the pneumoconioses to clarify the effect of degree of radiological abnormality on survival. A total of 1106 subjects were selected. Each subject's age, cumulative exposure to crocidolite, and time since first exposure were determined from employment records, the results of a survey of airborne concentrations of fibres > 5 mu in length conducted in 1966, and an exposure rating by an industrial hygienist and an ex-manager of the mine and mill at Wittenoom. By the end of 1986 193 subjects had died. Conditional logistic regression was used to model the relative risk of death in five separate case-control analyses in which the outcomes were deaths from: (1) all causes, (2) malignant mesothelioma, (3) lung cancer, (4) asbestosis, and (5) other causes excluding cancer and asbestosis. Up to 20 controls per case were randomly chosen from all men of the same age who were not known to have died before the date of death of the index case. After adjustment for exposure and time since first exposure, there were significant and independent effects of radiographic profusion and pleural thickening on all cause mortality. The effect of profusion was largely a result of the effect on mortality from malignant mesothelioma and asbestosis but not lung cancer. The effect of pleural thickening was greatest on mortality from other causes, mainly ischaemic heart disease. This study has shown that degree of radiographic abnormality has an independent effect on mortality from malignant mesothelioma, asbestosis, and all causes even after allowing for the effects of age, degree of exposure, and time since first exposure.
Risk factors for kidney cancer in New South Wales. IV. Occupation. M. McCredie, J.H. Stewart. 1993;50(4):349-54. PubMed · Publisher · Free full text

Abstract

In a population based case-control study of kidney cancer in New South Wales, data from structured interviews with 489 cases of renal cell cancer (RCC), 147 cases of renal pelvic cancer (CaRP), and 523 controls from the electoral roles were obtained about employment in certain industries or occupations, and exposure to particular chemicals chosen because of suspected associations with kidney cancer. A low level of education increased the risk for CaRP but not RCC. After adjustment for known risk factors, exposure to asbestos significantly increased the risk for RCC (relative risk (RR) = 1.62; 95% confidence interval (95% CI) 1.04-2.53). Working in the dry cleaning industry had a stronger link with CaRP (RR = 4.68; 95% CI 1.32-16.56) than with RCC (RR = 2.49; 95% CI 0.97-6.35). Working in the iron and steel industry doubled the risk for CaRP (RR = 2.13; 95% CI 1.04-4.39) whereas employment in the petroleum refining industry had a non-significant association with CaRP (RR = 2.60; 95% CI 0.88-7.63) and none with RCC.
Study of occupational lung cancer in asbestos factories in China. H. Zhu, Z. Wang. 1993;50(11):1039-42. PubMed · Publisher · Free full text

Abstract

A retrospective cohort study (1972-81) of occupational cancers in asbestos (chrysotile) factories has been previously published. In this paper the results of continued tracing and interviewing of members of this cohort from 1982 to 1986 is reported. The cohort included 5893 persons (45,974 person-years for men and 39,445 person-years for women). Malignant tumours played a large part in causes of death (36.9%). There were 183 cancers and 67 lung cancers among 496 deaths. The mortality due to lung cancer had a tendency to increase. By comparison with a control group, the RR of lung cancer was 5.32 (p < 0.01), and the SRR of lung cancer was 4.2 (p < 0.01), significantly higher than those of a control group. Among 148 cases of death from asbestosis there were 33 cases complicated with lung cancer (22.3%). The dose-response relations between exposure to asbestos and incidence of asbestosis and lung cancer were also studied in one asbestos factory. There was a positive correlation. A synergistic effect was found between cigarette smoking and lung cancer. Preventive and control measures and exposure limits for asbestos dust in the air of workplaces were recommended.
Synergistic effects of mineral fibres and cigarette smoke on the production of tumour necrosis factor by alveolar macrophages of rats. Y. Morimoto, M. Kido, I. Tanaka, et al. 1993;50(10):955-60. PubMed · Publisher · Free full text

Abstract

The objective of this study was to evaluate the combined effects of mineral fibres and cigarette smoke on the production of tumour necrosis factor (TNF) by alveolar macrophages. Rats were exposed to cigarette smoke in vivo, and production of TNF by alveolar macrophages was measured in the presence of mineral fibres in vitro. For smoke exposure, rats were divided into two groups. Five were exposed to a daily concentration of 10 mg/m3 of cigarette smoke for an eight hour period, and five rats (controls) were not exposed to smoke. Bronchoalveolar lavage was performed after exposure to smoke and the recovered alveolar macrophages were incubated with either chrysotile or ceramic fibres on a microplate for 24 hours. Activity of TNF in the supernatant was determined by the L-929 fibroblast cell bioassay. When alveolar macrophages were not stimulated by mineral fibres, production of TNF by rats exposed to smoke and unexposed rats was essentially the same. When alveolar macrophages were stimulated in vitro by chrysotile or ceramic fibres, production of TNF by alveolar macrophages from rats exposed to smoke was higher than that by alveolar macrophages from unexposed rats. The findings suggest that cigarette smoke and mineral fibres have a synergistic effect on TNF production by alveolar macrophages.
The 1891-1920 birth cohort of Quebec chrysotile miners and millers: mortality 1976-88. J.C. McDonald, F.D. Liddell, A. Dufresne, et al. 1993;50(12):1073-81. PubMed · Publisher · Free full text

Abstract

A cohort of some 11,000 men born 1891-1920 and employed for at least one month in the chrysotile mines and mills of Quebec, was established in 1966 and has been followed ever since. Of the 5351 men surviving into 1976, only 16 could not be traced; 2508 were still alive in 1989, and 2827 had died; by the end of 1992 a further 698 were known to have died, giving an overall mortality of almost 80%. This paper presents the results of analysis of mortality for the period 1976 to 1988 inclusive, obtained by the subject-years method, with Quebec mortality for reference. In many respects the standardised mortality ratios (SMRs) 20 years or more after first employment were similar to those for the period 1951-75--namely, all causes 1.07 (1951-75, 1.09); heart disease 1.02 (1.04); cerebrovascular disease 1.06 (1.07); external causes 1.17 (1.17). The SMR for lung cancer, however, rose from 1.25 to 1.39 and deaths from mesothelioma increased from eight (10 before review) to 25; deaths from respiratory tuberculosis fell from 57 to five. Among men whose exposure by age 55 was at least 300 million particles per cubic foot x years (mpcf.y), the SMR (all causes) was elevated in the two main mining regions, Asbestos and Thetford Mines, and for the small factory in Asbestos; so were the SMRs for lung cancer, ischaemic heart disease, cerebrovascular disease, and respiratory disease other than pneumoconiosis. Except for lung cancer, however, there was little convincing evidence of gradients over four classes of exposure, divided at 30, 100, and 300 mpcf.y. Over seven narrower categories of exposure up to 300 mpcf.y the SMR for lung cancer fluctuated around 1.27 with no indication of trend, but increased steeply above that level. Mortality form pneumoconiosis was strongly related to exposure, and the trend for mesothelioma was not dissimilar. Mortality generally was related systematically to cigarette smoking habit, recorded in life from 99% of survivors into 1976; smokers of 20 or more cigarettes a day had the highest SMRs not only for lung cancer but also for all causes, cancer of the stomach, pancreas, and larynx, and ischaemic heart disease. For lung cancer SMRs increased fivefold with smoking, but the increase with dust exposure was comparatively slight for non-smokers, lower again for ex-smokers, and negligible for smokers of at least 20 cigarettes a day; thus the asbestos-smoking interaction was less than multiplicative. Of the 33 deaths from mesothelioma in the cohort to date, 28 were in miners and millers and five were in employees of a small asbestos products factory where commercial amphiboles had also been used. Preliminary analysis also suggest that the risk of mesothelioma was higher in the mines and mills at Thetford Mines than in those at Asbestos. More detailed studies of these differences and of exposure-response relations for lung cancer are under way.
The importance of lung function, non-malignant diseases associated with asbestos, and symptoms as predictors of ischaemic heart disease in shipyard workers exposed to asbestos. A. Sandén, B. Järvholm, S. Larsson. 1993;50(9):785-90. PubMed · Publisher · Free full text

Abstract

The mortality from ischaemic heart disease was studied in a prospective cohort of 1725 shipyard workers exposed to asbestos. The analyses were stratified for age and smoking habits and restricted to men. In agreement with other findings, men with impaired lung function had a significantly higher risk (relative risk (RR) = 3.5) of dying from ischaemic heart disease than men with normal lung function. Men with asbestosis or suspected asbestosis had a significantly higher risk (RR = 3.1) of dying from ischaemic heart disease than men without asbestosis. Thus asbestosis or suspected asbestosis also seemed to be a risk factor for ischaemic heart disease. This finding was independent of respiratory function. There was no increased risk for ischaemic heart disease in men with compared with men without pleural plaques. Men with production of phlegm or sputum and wheezing or whistling had no increased risk for ischaemic heart disease compared with men without these symptoms. In the group with normal lung function men with dyspnoea had a significantly higher risk of dying from ischaemic heart disease than men without dyspnoea. The findings for men with asbestosis or suspected asbestosis indicated a further risk factor besides impaired lung function, in persons exposed to asbestos. Perhaps this risk factor is due to lesions of the pericardium with consequences for heart function.
A case-control study of occupational risk factors for laryngeal cancer. P. Wortley, T.L. Vaughan, S. Davis, et al. 1992;49(12):837-44. PubMed · Publisher · Free full text

Abstract

To determine whether specific jobs and occupational exposures are associated with laryngeal cancer lifetime occupational histories from a population-based case-control study in western Washington were examined. The study included 235 cases diagnosed between September 1983 and February 1987, and 547 controls identified by random digit dialing. After controlling for alcohol use, cigarette smoking, age and education, significantly increased risks were found for painters in construction (odds ratio (OR)) = 2.8, (95% confidence interval (95% CI) 1.1-6.9), supervisors and miscellaneous mechanics (OR = 2.3, 95% CI 1.1-4.8), construction workers (OR = 3.4, 95% CI 1.4-8.1), metalworking and plastic working machine operators (OR = 2.6, 95% CI 1.3-4.9) and handlers, and equipment cleaners and labourers (OR = 1.5, 95% CI 1.0-2.2). Allowing for a 10 year induction and latent period did not have a consistent effect on the associations. Potential exposures to asbestos, chromium, nickel, formaldehyde, diesel fumes, and cutting oils were assessed by using a job exposure matrix developed for this study. Three measures of exposure were examined--namely, peak, duration, and an intensity weighted exposure score. No significantly raised risks were seen, although increased risk was suggested among those exposed long term to formaldehyde in jobs with the highest exposures.
A new high resolution computed tomography scoring system for pulmonary fibrosis, pleural disease, and emphysema in patients with asbestos related disease. N.A. Jarad, P. Wilkinson, M.C. Pearson, et al. 1992;49(2):73-84. PubMed · Publisher · Free full text

Abstract

The aim of this study was to describe a scoring system for high resolution computed tomographic (HRCT) scans analogous to the International Labour Office (ILO) scoring system for plain chest radiographs in patients with asbestos related disease. Interstitial fibrosis, pleural disease, and emphysema were scored, the reproducibility and the interobserver agreement using this scoring system were examined, and the extent of the various types of disease was correlated with measurements of lung function. Sixty asbestos workers (five women and 55 men) mean age 59 (range 34-78) were studied. The lungs were divided into upper, middle, and lower thirds. An HRCT score for the extent of pleural disease and pulmonary disease in each third was recorded in a way analogous to the International Labour Office (ILO) method of scoring pleural and parenchymal disease on chest radiographs. A CT score for the extent of emphysema was also recorded. Pleural disease and interstitial fibrosis on the plain chest radiographs were assessed according to the ILO scoring system. A chest radiographic score for emphysema analogous to that used for HRCT was also recorded. Two independent readers assigned HRCT scores that differed by two categories or less in 96%, 92%, and 85% compared with 90%, 78%, and 79% of cases for chest radiographs for fibrosis, emphysema, and pleural disease respectively. There was better intraobserver repeatability for the HRCT scores than for the chest radiograph scores for all disorders. Multiple regression analysis showed that scores for interstitial fibrosis, emphysema, and pleural disease on chest radiographs and HRCT correlated to a similar degree with impairment of lung function.
An update of cancer mortality among chrysotile asbestos miners in Balangero, northern Italy. R. Calisti, P. De Giuli, G.L. Ghione. 1992;49(2):144. Case report · Comment · Letter PubMed · Publisher · Free full text

Summary

This letter responded to an update by Piolatto et al on cancer mortality among chrysotile miners at Balangero, northern Italy, and reported a further case of pleural mesothelioma in a former Balangero worker. The man, born in 1921, was admitted to a chest hospital near Turin in August 1989 with rapidly increasing breathlessness. Bloody pleural fluid contained large atypical cells, and thoracoscopy showed whitish masses on the right pleura. A biopsy led to a diagnosis of pleural mesothelioma being considered. He died in May 1990, and no necropsy was performed. A later review of the biopsy using immunocytochemistry (positive for vimentin, cytokeratin and EMA) confirmed the mesothelial nature of the lesion. His work documents showed that he worked at Balangero from 1936 to 1944, apart from about 15 months of military service. His jobs there included supplying drinking water to miners, sweeping dust after blasts, dry rock drilling and handling milled fibre, all in very dusty areas. He had also lived near Balangero until 1944 and recalled white dust from the mine and mill covering his house. The authors considered that he was substantially exposed only to chrysotile, although amphibole exposure could not be entirely ruled out. About 50 years passed between first exposure and clinical presentation. Because he was not included in the existing Balangero cohort, the authors suggested extending the cohort to workers employed before 1946 and lengthening follow up.

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Asbestos and cancer: history and public policy. W.K. Morgan. 1992;49(6):451. Comment · Historical article · Letter PubMed · Publisher · Free full text
Asbestos and cancer: history and public policy. M.P. Weller. 1992;49(1):70-2. Comment · Historical article · Letter PubMed · Publisher · Free full text
Asbestos and cancer: history and public policy. J.C. Kelso. 1992;49(7):526. Comment · Historical article · Letter PubMed · Publisher · Free full text
Biphasic lung diffusing capacity: detection of early asbestos induced changes in lung function. Z. Dujić, J. Tocilj, S. Boschi, et al. 1992;49(4):260-7. PubMed · Publisher · Free full text

Abstract

Asbestos related changes in the single breath carbon monoxide diffusing capacity (DLCO) were longitudinally analysed in 14 subjects exposed predominantly to chrysotile asbestos in an asbestos cement factory. These subjects were examined annually over the past nine years; their lung function was initially characterised with increased DLCO as the sole functional abnormality and they had normal chest radiographs. The radiological examination included a chest x ray film and, in the past two years, high resolution computed tomography (HRCT). A biphasic DLCO change was found: an initial increase followed by a relative decrease. The increase in DLCO was mainly caused by an increase in the membrane component (Dm). Indomethacin treatment applied after the sixth annual follow up significantly reduced DLCO and Dm. The decrease in DLCO correlated well with the parenchymal abnormalities found on HRCT, whereas the chest x ray film profusion score for small opacities (ILO classification) was unchanged. In conclusion, the data suggested that, as well as the absolute values of pulmonary function tests, the measurement of progression of functional parameters is essential in the assessment of pleural and parenchymal disease of the lung related to exposure to asbestos. High resolution computed tomography is suggested as the radiological method of choice in subjects with an isolated decrease in DLCO. Exposure to asbestos can be associated not only with a reduction in DLCO, but also with a temporary increase in DLCO caused by a subclinical inflammatory reaction.
Extreme airborne asbestos concentrations in a public building. E. Ganor, A. Fischbein, S. Brenner, et al. 1992;49(7):486-8. PubMed · Publisher · Free full text

Abstract

Fibre concentrations of asbestos were measured in the air of a communal dining room in which the damaged ceiling had a sprayed on coating of insulation containing asbestos. The average concentration of crocidolite asbestos fibres was 4 f/cm3, 20 times the highest air concentration that appears to have been reported previously for a public building. It is concluded that although air concentrations of asbestos fibres in public buildings containing asbestos insulation materials are usually low, high concentrations can occur. This may have implications for the risk of exposed persons developing diseases associated with asbestos.
Fibres and asbestos bodies in bronchoalveolar lavage fluids of asbestos sprayers. T. Tuomi, P. Oksa, S. Anttila, et al. 1992;49(7):480-5. PubMed · Publisher · Free full text

Abstract

The alveolar content of fibres and asbestos bodies was assessed by bronchoalveolar lavage (BAL) in 21 asbestos sprayers. Transmission and scanning electron microscopy (TEM and SEM) and two light microscopical (LM) methods, cytocentrifugation, and Millipore filtration were used. The subjects had been exposed mainly to crocidolite asbestos for an average of 2.8 (range 0.2-13) years in 1950-75. The mean (median) total fibre count (of asbestos bodies and uncoated fibres) per ml of BAL fluid was 5500 (2800) by TEM and 2900 (1000) by SEM. The mean (median) count of asbestos bodies per ml with LM was 810 (500) with cytocentrifugation and 750 (480) with Millipore filtration, 840 (320) by TEM, and 1750 (420) by SEM. The mean proportion of coated fibres was 35% by TEM and 45% by SEM. The mean length of the coated fibres was 22 (range 4-65) microns by TEM and 34 (range 4.5-170) microns by SEM. The total fibre count exceeded 1000 fibres per ml in 70% of the cases by TEM. Asbestos body counts exceeded 1 per ml in 95% of the cases by LM. The fibre counts by SEM were in good accordance with counts by TEM except in a few cases in which the TEM result was considerably higher. In these cases the proportion of coated fibres was also low. All four counting methods appeared to give consistent results in heavily exposed cases when fibre load in the lungs was high. The counting of asbestos bodies may, however, underestimate the total alveolar fibre load in some cases.
Histological type of lung carcinoma in asbestos cement workers and matched controls. L. Johansson, M. Albin, K. Jakobsson, et al. 1992;49(9):626-30. PubMed · Publisher · Free full text

Abstract

Histological types of lung carcinoma were examined in a case series of workers exposed to asbestos cement dust (n = 29) and matched controls (n = 87). The proportion of adenocarcinomas was 31% among the exposed subjects and 15% among the controls (mid-p = 0.05). Among workers with high exposure the proportion of adenocarcinoma was even higher (45%, 5/11; mid-p = 0.03). The proportion of peripheral tumours tended to be higher among exposed cases than controls (24 v 12%, mid-p = 0.12). Lobe of origin did not differ, however, between exposed cases and controls. Thus the study indicates an association between the degree of exposure to asbestos and adenocarcinoma of the lung, and a peripheral rather than central localisation of the tumours, but with virtually the same distribution of lobe of origin as in the general population.
Hydrogen peroxide release and hydroxyl radical formation in mixtures containing mineral fibres and human neutrophils. P. Leanderson, C. Tagesson. 1992;49(11):745-9. PubMed · Publisher · Free full text

Abstract

The ability of different mineral fibres (rock wool, glass wool, ceramic fibres, chrysotile A, chrysotile B, amosite, crocidolite, antophyllite, erionite, and wollastonite) to stimulate hydrogen peroxide (H2O2) and hydroxyl radical (OH.) formation in mixtures containing human polymorphonuclear leucocytes (PMNLs) was investigated. In the presence of azide, all the fibres caused considerable H2O2 formation, and about twice as much H2O2 was found in mixtures with the natural fibres (asbestos, erionite, and wollastonite) than in mixtures with the manmade fibres (rock wool, glass wool, and ceramic fibres). In the presence of externally added iron, all the fibres were found to generate OH. and the natural fibres caused about three times more OH. formation than the manmade fibres. In the absence of external iron, there was less OH. formation; however, amosite, crocidolite, antophyllite, erionite, and wollastonite still generated considerable amounts of OH., also under circumstances in which only small amounts of OH. were produced in mixtures with the manmade fibres. These findings indicate that natural fibres generate more H2O2 and OH. than manmade fibres when incubated with PMNLs in the presence of external iron. They also suggest that the natural fibres, amosite, crocidolite, antophyllite, erionite, and wollastonite may act catalytically in the dissociation of H2O2 to OH. in the absence of external iron, whereas manmade fibres such as rock wool, glass wool, and ceramic fibres, do not seem to be able to generate OH. in the absence of external iron.
Long term radiological effects of short term exposure to amosite asbestos among factory workers. R. Ehrlich, R. Lilis, E. Chan, et al. 1992;49(4):268-75. PubMed · Publisher · Free full text

Abstract

Chest radiographs were read from a sub-cohort of 386 factory workers with short term exposure to amosite asbestos (median exposure six months) and long follow up (median 25 years). Prevalence of abnormality was determined independently by two readers from the first film available after 20 years from first employment. Serial films were obtainable for 238 men (median interval from first to last film: nine years). Progression was classified with a direct progression scoring scale. Individual dust exposure estimates were derived from dust counts from two similar plants. With as little as one month or less of employment, about 20% of the films showed parenchymal abnormality and about a third showed pleural abnormality. Those in the lowest cumulative exposure stratum (less than 5 fibre-years/ml) were similarly found to have high rates of abnormality. Dose-response relations were present in the data of both readers. Smokers had higher rates of parenchymal abnormality. On multivariate analysis, cumulative exposure was the exposure variable most closely related to parenchymal abnormality, and time from first employment was the variable most closely related to pleural abnormality. Progression (including first attacks) 20 or more years after ceasing employment occurred and was more common for pleural than for parenchymal abnormality. It is concluded that with exposure to high concentrations to amosite such as existed in this factory and with follow up for at least 20 years, (1) exposure for as little as a month was sufficient to produce radiological signs of parenchymal and pleural fibrosis, (2) no cumulative exposure threshold for parenchymal and pleural fibrosis was detectable, and (3) parenchymal and pleural progression were still detectable >/= 20 years after the end of exposure.
Low dose exposure to natural and man made fibres and the risk of cancer: towards a collaborative European epidemiology. Report of a workshop held in Paris , 10-12 June, 1991. A.J. Valleron, J. Bignon, J.M. Hughes, et al. 1992;49(9):606-14. PubMed · Publisher · Free full text

Summary

This report summarised a workshop held in Paris on 10-12 June 1991 on the risk of cancer from low dose exposure to natural fibres such as asbestos and to man made mineral fibres (MMMFs). The workshop aimed to update knowledge of these risks and to outline suitable epidemiological methods for studying low, repeated exposures to carcinogens. Scientists from 13 European countries, North and South America, Japan and Africa took part. Sessions covered seven themes, each led by a moderator: dose-effect relations at low exposure, laboratory approaches, measurement of dose, exposure standards, cofactors, methods for collaborative epidemiology, and tools for pooling data. Ten ongoing European studies were also presented. Participants reported that, fibre for fibre, risk appeared greater for amphibole than for chrysotile and for long than for short fibres. Extrapolating occupational dose-response data to low levels, such as those in buildings, suggested public health risks below what can reasonably be measured. Risks below measurable levels, and for custodians and maintenance workers exposed to peaks, remained unanswered. Glass wool and continuous filament glass had not been associated with increased lung cancer risk. Risk from slag and rock wools remained controversial. Special attention was urged for long, thin, durable fibres such as some ceramic fibres. Because huge sample sizes would be needed, the report concluded that multicentre studies are essential.

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Lung cancer and occupation: results of a multicentre case-control study. A. Morabia, S. Markowitz, K. Garibaldi, et al. 1992;49(10):721-7. PubMed · Publisher · Free full text

Abstract

The objective of the current study was to estimate the risk of lung cancer attributable to occupational factors and not due to tobacco. At 24 hospitals in nine metropolitan areas in the United States, 1793 male lung cancer cases were matched for race, age, hospital, year of interview, and cigarette smoking (never smoker, ex-smoker, smoker (1-19 and > or = 20 cigarettes per day)) to two types of controls (cancer and non-cancer hospital patients). Information on usual occupation, exposure to specific potential carcinogens, and cigarette smoking was obtained by interview. Risk of lung cancer was increased significantly for electricians; sheetmetal workers and tinsmiths; bookbinders and related printing trade workers; cranemen, derrickmen, and hoistmen; moulders, heat treaters, annealers and other heated metal workers; and construction labourers. All of these occupations are potentially exposed to known carcinogens. Odds ratios (ORs) were increased for exposure to coal dust (adjusted OR = 1.5; 95% confidence interval (95% CI) 1.1-2.1). After stratification, this association was statistically significant only after 10 or more years of exposure. Lung cancer was also related to exposure to asbestos (adjusted OR = 1.8; 95% CI 1.5-2.2). The ORs increased with increasing duration of exposure to asbestos for all smoking categories except for current smokers of 1-19 cigarettes per day. The statistical power to detect ORs among occupations that were previously reported to be at increased risk of lung cancer but that failed to show an OR of at least 1.5 in the current study was small. The cumulative population attributable risk (PAR) of lung cancer due to occupation was 9.2%. It is concluded that occupational factors play an important part in the development of lung cancer independently of cigarette smoking. Because occupations at high risk of lung cancer were under-represented, the cumulative PAR of the present study is likely to be an underestimate of the true contribution of occupation to risk of lung cancer.
Lymphocyte subsets in subjects exposed to asbestos: changes in circulating natural killer cells. N. al Jarad, M. Macey, S. Uthayakumar, et al. 1992;49(11):811-4. PubMed · Publisher · Free full text

Summary

The authors examined whether circulating lymphocyte subsets, particularly natural killer (NK) cells, differed in people exposed to asbestos. Earlier studies had used only the CD16 antibody to identify NK cells; this study used both CD16 and CD57. The subjects were 16 men with asbestosis, 11 male asbestos workers without asbestosis, and 24 control subjects (two women; 16 smokers and eight non-smokers), studied at hospitals in London. None had clinical evidence of malignancy, radiological evidence of lung cancer, or connective tissue disorders. Blood lymphocytes were separated, frozen and stored, then analysed in batches by flow cytometry with antibodies to CD4, CD8, CD16 and CD57. Absolute counts were also measured. Total lymphocyte numbers were similar in all groups. Compared with controls, the total exposed group had fewer CD16 positive cells (mean 0.21 v 0.31; p = 0.014) and a lower proportion of them (median 11% v 17%; p = 0.048). CD57 positive cells and CD4:CD8 ratios did not differ. No differences were found between workers with and without asbestosis, or between current smokers and non-smokers and ex-smokers combined. CD16 cell numbers correlated inversely with duration of asbestos exposure (r = -0.44, p = 0.026). The authors concluded that circulating CD16 positive cells are reduced in people exposed to asbestos, more so with longer exposure. They suggested this may partly explain asbestos workers' increased susceptibility to malignancies.

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Malignant pleural mesothelioma caused by non-occupational childhood exposure to asbestos. A. Cazzadori, F. Malesani, L. Romeo. 1992;49(8):599. Case report PubMed · Publisher · Free full text
Occupational and other environmental factors and multiple myeloma: a population based case-control study. M. Eriksson, M. Karlsson. 1992;49(2):95-103. PubMed · Publisher · Free full text

Abstract

Epidemiological studies on the aetiology of multiple myeloma are reviewed as a background to this population based case-control study performed in an area with a high incidence of multiple myeloma. The purpose was to identify and evaluate several suspected environmental factors in relation to this disease. A total of 275 confirmed cases diagnosed in four counties in northern Sweden during four years were compared with the same number of control subjects drawn from population registries. The controls were matched for age, sex, county, and vital status. Occupations and work associated exposures to chemicals and other potential carcinogens were assessed by an extensive questionnaire that also included questions on smoking habits, residential building materials, vicinity to electrical power lines, and leisure time contact with animals, electrical equipment, and chemicals. Information obtained from the questionnaires was completed by telephone interviews when necessary. Univariate analysis and multivariate logistic regression were performed. The study confirmed an association found earlier between farming and multiple myeloma. Some domestic animals (cattle, horses, and goats) and two types of pesticides (phenoxyacetic acids and DDT) were indicated as risk factors within farming. Exposure to electromagnetic fields, asbestos, and organic solvents were negatively associated with myeloma in this study.
Prediction of mesothelioma, lung cancer, and asbestosis in former Wittenoom asbestos workers. A. Rogers. 1992;49(6):451-2. Comment · Letter PubMed · Publisher · Free full text

Summary

In this letter, the author commented on models used by Berry (1991) to predict future mesothelioma incidence among people exposed at the Wittenoom crocidolite mine in Western Australia. The letter dealt only with mesothelioma. The author noted that Berry's estimates depended on the values chosen for lag time and lung clearance rates, that the assumption of reduced toxicity from fibre clearance was speculative, and that de Klerk et al had produced somewhat higher predictions. As an alternative, the author used the distribution of time since first asbestos exposure taken from occupational histories in the Australian Mesothelioma Surveillance Program. Assuming the same latency distribution applied to Wittenoom cases collected in 1980-5, the author calculated the total cases expected for each period of first employment and the number expected in each period of diagnosis. The author acknowledged that the method included environmentally exposed cases and assumed a similar distribution of age, occupation and exposure over the mine's operation, assumptions stated to be known to be incorrect. It also assumed the Wittenoom group was comparable with the whole Australian population. An estimate of 71 cases was considered reasonable compared with the 59 cases reported to the Australian register in 1986-90. The method predicted 525 mesotheliomas among the 6505 male and 411 female workers and past residents. Of these, 366 would occur in 1986-2020, peaking in 1991-95 and tailing off over the next 25 years. The author concluded that this fitted comfortably within the range of most likely values presented by Berry.

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Pulmonary effects of exposure to fine fibreglass: irregular opacities and small airways obstruction. K.H. Kilburn, D. Powers, R.H. Warshaw. 1992;49(10):714-20. PubMed · Publisher · Free full text

Abstract

Objective: Man made mineral fibres imitate asbestos and produce tumours of the pleura in animals. To answer the question, Does prolonged exposure to fibreglass adversely affect pulmonary function or produce radiographic abnormalities in human subjects? we studied workers in a midwestern appliance plant where refrigerator doors and previously entire cabinets were insulated with fibreglass sheeting and loose rotary spun fibreglass.

Methods: Spirometry and lung volumes were measured, respiratory and occupational questionnaires were administered, and chest x-ray films were read for pneumoconiosis using International Labour Office (ILO) 1980 criteria in 284 workers with exposure of 20 years or more.

Results: Expiratory flows were reduced including FEV1 (mean 90.3% of predicted (pr), FEF25-75 (85.5% pr), and FEF75-85 (76.2% pr). Forced vital capacity was significantly reduced (92.8% pr) and total lung capacity was significantly increased (109.2% pr). In white male smokers, a group large enough for comparisons, parameters of pulmonary function were reduced further in the presence of irregular opacities. Forty three workers (15.1%) had evidence of pneumoconiosis on chest radiographs: 26 of these (9.1%), had no known exposure to asbestos and 17 (6.0%) had some exposure. The best judgement was that in 36 (13.0%), pulmonary opacities or pleural abnormalities were due to fibreglass.

Conclusion: Commercial rotary spun fibreglass used for insulating appliances appears to produce human disease that is similar to asbestosis.
Survival of asbestos insulation workers with mesothelioma. J. Ribak, I.J. Selikoff. 1992;49(10):732-5. PubMed · Publisher · Free full text

Abstract

Malignant mesothelioma is a lethal disease. It is rare in the general population; however, workers exposed to asbestos suffer significant burdens of the neoplasm. The survival time of 457 consecutive fatal cases of pleural and peritoneal mesothelioma that occurred among 17,800 asbestos insulation workers observed prospectively from 1 January 1967 to 1 January 1987 was studied. Mean survival time from initial presentation of the disease to death was 11.4 months for the pleural mesothelioma patients compared with 7.4 months for the peritoneal group. This difference was statistically significant. Mean survival time from diagnosis to death was shorter for both groups of patients: 8.4 months for pleural mesothelioma v 5.8 months for the peritoneal cases. In conclusion, survival time in mesothelioma patients is short; most die within a year from the onset of the initial symptoms. No effective therapy is yet available.
The histocompatibility antigen in asbestos related disease. N. Al Jarad, S. Uthayakumar, E.J. Buckland, et al. 1992;49(12):826-31. PubMed · Publisher · Free full text

Abstract

Thirty nine phenotypes of human leucocyte antigens (HLA)-A-B-DR and DQ were obtained from 99 asbestos workers (one woman and 98 men). Presence or absence of antinuclear antibodies and rheumatoid factor was determined in 91 of them. Workers were divided into five groups: asbestos workers with no apparent disease (AW; n = 17), diffuse benign pleural disease (PD; n = 31), asbestosis (AS; n = 24), asbestosis with lung cancer (AS-CA; n = 14), and mesothelioma (M; n = 13). Compared with AW, several trends of differences of HLA antigen prevalence were found in patients with asbestos related disease, but these did not achieve statistical significance when p was corrected (pcorr) by number of analyses undertaken. Analysis of the results obtained in previous studies together with the results of this study showed that compared with AW, AS patients had decreased prevalence of HLA-DR5 (pcorr < 0.02). Reasons for the differences in results of previous studies and statistical methods commonly used to compare prevalences of HLA antigen are discussed.
The mortality of amphibole miners in South Africa, 1946-80. G.K. Sluis-Cremer, F.D. Liddell, W.P. Logan, et al. 1992;49(8):566-75. PubMed · Publisher · Free full text

Abstract

A cohort was established in 1981 of all 7317 white male employees in the amosite and crocidolite mines in South Africa whose names had appeared in the personnel records (initiated between 1945 and 1955) of the major companies. Some of the men had been employed as early as 1925, but only 8% had had more than 10 years of service. Three subcohorts were defined: 3212 men whose only exposure to asbestos was to amosite; 3430 exposed to crocidolite; and 675 to both amphiboles. No deaths or losses to view occurred before 1946, and 5925 men (81%) were known to be alive at the end of 1980. Losses to view numbered 167 (2%), and there had been 1225 deaths (17%), an excess of 331 over the number of deaths expected on the basis of the mortality of all white South African males. The fibre related excesses were of mesothelioma, lung cancer, and other respiratory diseases, but there were other excesses perhaps mainly related to socioeconomic factors including lifestyle. When cause of death was determined according to "best evidence" (after study of clinical, radiological, biopsy, and necropsy reports in conjunction with the death certificate), there were 30 deaths due to mesothelioma (22 pleural, six peritoneal, two other) and 65 due to cancer of trachea, bronchus, and lung. Various analyses of these deaths showed that crocidolite had higher toxicity than amosite for lung cancer and this was most pronounced for mesothelioma; there can now be no question that crocidolite is far more dangerous than amosite at least in so far as mesothelioma is concerned. Nevertheless, crocidolite induced mesothelioma appeared only in men who had been exposed for long periods, at least 12 months, but on average about 15 years.
A historical prospective study of European stainless steel, mild steel, and shipyard welders. L. Simonato, A.C. Fletcher, A. Andersen, et al. 1991;48(3):145-54. PubMed · Publisher · Free full text

Abstract

A multicentre cohort of 11,092 male welders from 135 companies located in nine European countries has been assembled with the aim of investigating the relation of potential cancer risk, lung cancer in particular, with occupational exposure. The observation period and the criteria for inclusion of welders varied from country to country. Follow up was successful for 96.9% of the cohort and observed numbers of deaths (and for some countries incident cancer cases) were compared with expected numbers calculated from national reference rates. Mortality and cancer incidence ratios were analysed by cause category, time since first exposure, duration of employment, and estimated cumulative dose to total fumes, chromium (Cr), Cr VI, and nickel (Ni). Overall a statistically significant excess was reported for mortality from lung cancer (116 observed v 86.81 expected deaths, SMR = 134). When analysed by type of welding an increasing pattern with time since first exposure was present for both mild steel and stainless steel welders, which was more noticeable for the subcohort of predominantly stainless steel welders. No clear relation was apparent between mortality from lung cancer and duration of exposure to or estimated cumulative dose of Ni or Cr. Whereas the patterns of lung cancer mortality in these results suggest that the risk of lung cancer is higher for stainless steel than mild steel welders the different level of risk for these two categories of welding exposure cannot be quantified with precision. The report of five deaths from pleural mesothelioma unrelated to the type of welding draws attention to the risk of exposure to asbestos in welding activities.
A prospective study in the Australian petroleum industry. I. Mortality. D. Christie, K. Robinson, I. Gordon, et al. 1991;48(8):507-10. PubMed · Publisher · Free full text

Abstract

This paper reports the mortality experience of employees of the Australian petroleum industry from 1981 to 1989. Two surveys by personal interview incorporated more than 15,000 employees representing 92% of the eligible population. Subjects were included in the analysis after completing five years of service in the industry. At the time of this report the cohort does not include sufficiently large numbers of women for useful analysis; results presented are restricted to men. By 31 December 1989, 76,529 person-years of observation had accumulated for male mortality with 241 deaths. The standardised mortality ratio (SMR) analysis showed a favourable mortality experience for most causes with overall cancer rates slightly lower than those of the national population. Whereas deficits were seen in some cancer sites, notably lung cancers (SMR 0.5, 95% confidence interval (95% CI) 0.3-0.8), mortality for lymphohaematopoietic cancers, notably leukaemia (SMR 1.6, 95% CI 0.6-3.4) suggested increased risk. The SMR for cancers of the pleura was 3.9 (95% CI 0.8-11). Two of the three cases seen had previous employment, however, in industries with likely exposure to asbestos.
Analysis of lung asbestos content. A. Churg. 1991;48(10):649-52. Editorial PubMed · Publisher · Free full text

Summary

The author reviewed what analysis of lung asbestos content by analytical electron microscopy could and could not show. He noted that absolute fibre concentrations varied widely between laboratories, even for the same sample, so a single value from one laboratory was meaningless and each laboratory needed its own background ranges. However, in a seven-laboratory trial all laboratories identified high and low samples correctly, and fibre burdens correlated well with exposures estimated from air sampling. Chrysotile was retained poorly in lung compared with amphiboles, so chrysotile exposure could be missed. Tremolite content and fibre length could help: in the author's work, chrysotile or tremolite fibres longer than 8 µm were highly specific for occupational exposure. In the author's laboratory the upper 95th percentile for the Vancouver general population was around 1 000 000 fibres each of chrysotile and tremolite and 10 000 fibres of amosite plus crocidolite per g of lung tissue. Residents of Quebec chrysotile mining townships who were never employed in the industry carried five- to tenfold more chrysotile than urban dwellers, without evidence of asbestos-related disease. The author concluded that some fibre burden can be tolerated without disease. He also concluded that chrysotile with its tremolite contaminant can cause mesothelioma, but only at very high fibre loads. In his laboratory, disease appeared at about one order of magnitude lower amphibole than chrysotile burden, and he concluded that chrysotile is less pathogenic than amphiboles. The effects of fibre size and distribution remained unclear.

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Asbestos and cancer: history and public policy. B.I. Castleman. 1991;48(6):427-32. Comment · Letter PubMed · Publisher · Free full text

Summary

In this letter, Castleman responded to Murray's statements in the journal that there had been no knowledge of lung cancer or mesothelioma attributable to asbestos during the second world war. He reviewed publications of the 1930s and 1940s. These included case reports of lung cancer with asbestosis, Nordmann's 1938 German paper on the occupational cancer of asbestos workers, and 1943 German legislation treating such lung cancer as an occupational disease. British factory inspectors reported 12 lung cancers among 103 autopsied asbestosis cases (11.6%) as of 1938, when lung cancer was seen in less than 1% of UK autopsies. By 1947 they reported cancer of the lung or pleura in 31 of 235 deaths with asbestosis (13.2%). Castleman then described company documents, discovered through legal proceedings in the 1980s, on industry-sponsored research at the Saranac Laboratory. In 1943 Gardner told sponsors that 8 of 11 mice inhaling long fibre asbestos had developed malignant lung tumours. These findings were not published. In 1948 sponsoring companies decided unanimously to strike all references to cancer and tumours from Vorwald's report, which was published in 1951 without them. Castleman concluded that this suppression was reprehensible and allowed a scientific controversy to be maintained beyond the 1940s. In a reply, Murray stated that his review of Castleman's book had never been submitted, and he reproduced the review.

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Asbestos related malignancy and the Cairns hypothesis. K. Browne. 1991;48(2):73-6. Editorial PubMed · Publisher · Free full text

Summary

This editorial, by Kevin Browne of the Department of Occupational Medicine, National Heart and Lung Institute, London, examined whether asbestos-related cancer could be explained by Cairns' hypothesis. That hypothesis holds that cells have evolved a natural mechanism protecting against harmful mutations arising during cell division, and that chronic cell proliferation can disrupt it. Drawing on published animal, pathological and epidemiological evidence, the author noted that asbestos is not a mutagen, that attempts to show direct malignant transformation had failed or required unrealistic in vitro conditions, and that fibres shorter than 5 µm appeared to be neither fibrogenic nor carcinogenic. He described asbestosis as resulting from mediators released by macrophages after incomplete ingestion of long fibres, with a generally accepted threshold of 25 fibre/ml years. He argued that the same excess of growth factors drives the epithelial proliferation leading to lung cancer. In support he cited increased lung cancer in fibrosis from other causes, and two studies finding increased lung cancer risk only in the presence of asbestosis. He interpreted the more than additive effect of smoking as asbestos acting as a promoter. For mesothelioma he cited inflammatory change preceding tumours, a suggested threshold of about five fibres/ml-years for amphiboles, a longer latent period at lower doses reported by four research groups, and tumours produced by non-asbestos fibres. The author concluded that asbestos-related malignancy does not result from direct genotoxic action, is subject to threshold and dose-response effects, and is consistent with disruption of the protective mechanism suggested by Cairns.

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Asbestosis as a precursor of asbestos related lung cancer: results of a prospective mortality study. J.M. Hughes, H. Weill. 1991;48(4):229-33. PubMed · Publisher · Free full text

Abstract

A prospective mortality study of 839 men employed in the manufacture of asbestos cement products in 1969 examined lung cancer risk in relation to lung fibrosis seen on chest x ray film, controlling for age, smoking, and exposure to asbestos. Twenty or more years after hire, no excess of lung cancer was found among workers without radiographically detectable lung fibrosis, even among long term workers (greater than or equal to 21.5 years); nor was there a trend in risk by level of cumulative exposure to asbestos among such workers. By contrast, employees with small opacities (greater than or equal to 1/0; ILO classification) experienced a significantly raised risk of lung cancer (nine observed deaths v 2.1 expected), even though their exposures to asbestos were similar to the exposures of long term workers without opacities. In this population, excess risk of lung cancer was restricted to workers with x ray film evidence of asbestosis, a finding consistent with the view that asbestos is a lung carcinogen because of its fibrogenicity.
Asbestosis, laryngeal carcinoma, and malignant peritoneal mesothelioma in an insulation worker. A. Fischbein, J.C. Luo, G.R. Pinkston. 1991;48(5):338-41. Case report PubMed · Publisher · Free full text

Abstract

Asbestos associated diseases consist of both benign and malignant conditions. A rare constellation of asbestosis, laryngeal carcinoma, and malignant peritoneal mesothelioma occurring in a patient with long term occupational exposure to airborne asbestos fibres is presented. The observation illustrates the powerful disease-causing potential of occupational exposure to asbestos. A brief discussion of multiple primary neoplasms associated with exposure to asbestos is also presented.
Bronchiolitis in a patient with talcosis. K. Reijula, P. Pääkkö, R. Kerttula, et al. 1991;48(2):140-2. Case report PubMed · Publisher · Free full text
Characterisation of palygorskite specimens from different geological locales for health hazard evaluation. R.P. Nolan, A.M. Langer, G.B. Herson. 1991;48(7):463-75. PubMed · Publisher · Free full text

Abstract

Palygorskite, a fibrous clay mineral, is being used as a substitute for asbestos in some applications. Nine specimens obtained from different geological locales were studied for mineral purity, elemental composition, fibre size distribution, and surface binding characteristics. The membranolytic activity of each was determined using a human erythrocyte model. The membranolytic behaviour and surface binding characteristics were compared with three chrysotile specimens employed as positive controls. The palygorskite specimens derived from the different geological locales display a range of physicochemical properties. This study shows the importance of selecting several mineral specimens for a health hazard evaluation. The current carcinogenic classification of the mineral may be limited due to the number of specimens used for that particular evaluation.
Characterisation of respiratory health and exposures at a sintered permanent magnet manufacturer. J.F. Deng, T. Sinks, L. Elliot, et al. 1991;48(9):609-15. PubMed · Publisher · Free full text

Abstract

Sintered permanent magnets are made from the powdered metals of cobalt, nickel, aluminium, and various rare earths. During production, exposure to respirable crystalline silica and asbestos may also occur. Reported here is a cross sectional study of 310 current and 52 retired hourly employees who worked 10 or more years making sintered magnets. Each participant had a chest radiograph, spirometry, and completed a respiratory questionnaire. Illness logs were also reviewed to calculate the incidence of recorded respiratory disorders. The prevalences of abnormalities in pulmonary function and respiratory symptoms were not higher than found in an external referent population. Although the prevalence of diffuse parenchymal opacities consistent with pneumoconiosis (four workers) was similar to the referent population, one worker had radiographic findings consistent with silicosis and two workers had profusion scores of 1/2 or above, not seen in the referent group. The incidence of reported respiratory conditions in the log, including asthma, was 10 times that of other manufacturers in the same industrial classification category. Excessive exposures to cobalt, nickel, and respirable silica were shown by environmental measurements.
Cigarette smoking and small irregular opacities. W. Weiss. 1991;48(12):841-4. PubMed · Publisher · Free full text

Abstract

A survey of chemical workers by chest roentgenograms was designed to determine whether exposure to acrylic dust and/or cigarette smoking was associated with diffuse abnormalities suggestive of pneumoconiosis. The films were examined without knowledge of dust exposure or smoking habits. The International Labour Office (ILO) classification and standard films were used. Workers with exposure to asbestos were excluded. There was no relation between prevalence of abnormalities and exposure to dust. Among 181 workers 28 had s and/or t small irregular opacities with profusion of 0/1 (23), 1/0 (three), or 1/1 (two). These findings were present in 20% of smokers compared with 2.2% of non-smokers. The prevalence increased with increasing age to 31.6% among smokers aged 50-64. Prevalence was 10% among ex-smokers of cigarettes. Among current cigarette smokers, prevalence was 5.3% in those who smoked less than one pack per day, 31.3% in heavier cigarette smokers, and 52.9% in 17 heavy cigarette smokers aged 50-64. Profusions of 0/1 and 1/0 are classified as "suspect" pneumoconiosis according to the ILO guidelines. The data in this study indicate that such abnormalities are directly related to age and smoking habits among workers not exposed to hazardous dust.
Desquamative interstitial pneumonia associated with chrysotile asbestos fibres. J.A. Freed, A. Miller, R.E. Gordon, et al. 1991;48(5):332-7. Case report PubMed · Publisher · Free full text

Abstract

The drywall construction trade has in the past been associated with exposure to airborne asbestos fibres. This paper reports a drywall construction worker with 32 years of dust exposure who developed dyspnoea and diminished diffusing capacity, and showed diffuse irregular opacities on chest radiography. He did not respond to treatment with corticosteroids. Open lung biopsy examination showed desquamative interstitial pneumonia. Only a single ferruginous body was seen on frozen section, but tissue examination by electron microscopy showed an extraordinary pulmonary burden of mineral dust with especially high concentrations of chrysotile asbestos fibres. This report emphasises the need to consider asbestos fibre as an agent in the aetiology of desquamative interstitial pneumonia. The coexistent slight interstitial fibrosis present in this case is also considered to have resulted from exposure to mineral dust, particularly ultramicroscopic asbestos fibres.
Early detection of interstitial lung disease in asbestos exposed non-smoking workers by mid-expiratory flow rate and high resolution computed tomography. Z. Dujić, J. Tocilj, M. Saric. 1991;48(10):663-4. PubMed · Publisher · Free full text

Abstract

Ten years of lung function and radiological findings in six non-smoking asbestos exposed subjects who had increased mid-expiratory flow rate (FEF 25-75%) as the only functional abnormality were prospectively analysed. A biphasic change in FEF25-75% was noted. It initially increased up to the fifth year, and then a decrease was seen. In the final three years of the study, FEF25-75% reduction correlated well with a decrease in pulmonary capacity for CO (DLCO). During that time high resolution computed tomography (HRCT) probability scores correlated inversely with FEF25-75% and with DLCO, whereas chest radiography was unchanged (International Labour Organisation (ILO) profusion below 1/1). For five of the six subjects HRCT probability of asbestosis was intermediate. An increase in FEF25-75% in some asbestos exposed non-smoking workers may be one of the earliest functional signs indicative of future development of parenchymal asbestosis. Early asbestos related parenchymal abnormalities are seen more frequently on HRCT than on chest radiography.
Exposure to cement dust at a Portland cement factory and the risk of cancer. J. Vestbo, K.M. Knudsen, E. Raffn, et al. 1991;48(12):803-7. PubMed · Publisher · Free full text

Abstract

The relation between exposure to cement dust and cancer was examined in a population of 546 cement workers and a reference population of 858 randomly sampled men of similar age and area of residence. In 1974 all men gave lifelong occupational and smoking histories; information on incidence of cancer in the period 1974-85 was obtained from the Danish Cancer Registry. No increased risk of overall cancer was found among cement workers. Among men with more than 20 years exposure to cement dust, 14 cases of respiratory cancer were observed (observed/expected (O/E) 1.52, 95% confidence interval (95% CI) 0.90-2.57) when compared with all Danish men. Men with 1-20 years exposure had O/E 1.14 (95% CI 0.59-2.19) based on nine cases of cancer. After excluding all men with documented exposure to asbestos during employment in an asbestos cement factory no increased risk of overall cancer or respiratory cancer was found among cement workers compared with white collar workers from the local reference population, using a Cox regression model controlling for age and smoking habits. Relative risks were 0.5 (95% CI 0.1-1.5) and 1.0 (95% CI 0.4-2.6) for men with 1-20 and more than 20 years of exposure to cement dust respectively compared with white collar workers.
Fibre distribution in the lungs and pleura of subjects with asbestos related diffuse pleural fibrosis. A.R. Gibbs, M. Stephens, D.M. Griffiths, et al. 1991;48(11):762-70. PubMed · Publisher · Free full text

Abstract

The lungs from 13 cases of diffuse pleural fibrosis associated with a history of exposure to asbestos were examined. Samples were taken from the visceral pleura and central and subpleural zones of the lungs for histopathological and mineralogical studies. The fibre type, size, and number were estimated for each of these regions by transmission electron microscopy and energy dispersive x ray analysis. Amphibole fibre counts were raised when compared with a non-occupationally exposed group and matched those seen in cases of pleural plaques, mild asbestosis, and mesothelioma. A wide case to case variation of distribution was seen. No significant difference was apparent between central and subpleural zones, whereas low asbestos counts were found in the pleura; these were mainly short chrysotile fibres. Within the lungs more (45%) of the longer (greater than 4 microns) and thinner (less than 0.25 micron) amphibole fibres were retained in keeping with other studies implicating such fibre profiles in the pathogenesis of asbestos related disease.
Frequency of sister chromatid exchange and chromosomal aberrations in asbestos cement workers. N. Fatma, A.K. Jain, Q. Rahman. 1991;48(2):103-5. PubMed · Publisher · Free full text

Abstract

Exposure to asbestos minerals has been associated with a wide variety of adverse health effects including lung cancer, pleural mesothelioma, and cancer of other organs. It was shown previously that asbestos samples collected from a local asbestos factory enhanced sister chromatid exchanges (SCEs) and chromosomal aberrations in vitro using human lymphocytes. In the present study, 22 workers from the same factory and 12 controls were further investigated. Controls were matched for age, sex, and socioeconomic state. The peripheral blood lymphocytes were cultured and harvested at 48 hours for studies of chromosomal aberrations and at 72 hours for SCE frequency determinations. Asbestos workers had a raised mean SCE rate and increased numbers of chromosomal aberrations compared with a control population. Most of the chromosomal aberrations were chromatid gap and break types.
Lung dust content in idiopathic pulmonary fibrosis: a study with scanning electron microscopy and energy dispersive x ray analysis. E. Monsó, J.M. Tura, J. Pujadas, et al. 1991;48(5):327-31. PubMed · Publisher · Free full text

Abstract

Examination with an optical microscope and polarised light is not sensitive enough to detect low diameter asbestos fibres. This limitation implies that some cases of asbestosis can be erroneously diagnosed as idiopathic pulmonary fibrosis (IPF) if asbestos bodies are not found in the standard examination of abnormal tissue. To determine whether IPF is over-diagnosed, a study was carried out with scanning electron microscopy (SEM) and energy dispersive x ray analysis (EDXA) on 25 samples previously diagnosed as IPF at the standard examination. Scanning electron microscopy will show the presence of low diameter fibres in the lung without tissue destruction, and these fibres can be identified using EDXA. The quantitative and qualitative results for lung tissue from patients diagnosed as having IPF were compared with the results of the examination of 25 samples of normal lung. Most of the samples from patients diagnosed as having IPF showed only occasional inorganic particles (less than 10 particles/SEM field at 160 x), results equivalent to the results obtained in normal lung. Two cases of IPF, however, showed innumerable asbestos fibres (greater than 100 fibres/SEM field). One of these two patients had an antecedent of brief exposure to asbestos. No environmental antecedent was found in the second patient. Asbestosis was the final diagnosis for these two patients. The examination of inorganic particles in normal lungs showed mainly non-fibrous silicates (61.4%) and particles of heavy elements (34.9%). Only one asbestos fibre was found (0.9%). It is concluded that standard pathological techniques overdiagnose IPF in a few cases in which asbestos bodies are not found with the optical microscope.
Occupational exposure to asbestos as evaluated from work histories and analysis of lung tissues from patients with mesothelioma. T. Tuomi, M.S. Huuskonen, L. Tammilehto, et al. 1991;48(1):48-52. PubMed · Publisher · Free full text

Abstract

The past occupational exposure to asbestos of 23 patients with mesothelioma (21 men and two women) has been evaluated by a personal interview of their work history and by determination of the fibre burden in their lung tissue with scanning electron microscopy (SEM) and x ray microanalysis. According to the work history, nine patients (39%) had definitely been or probably been exposed to asbestos, six patients (26%) had had possible exposures, and eight patients (35%) unlikely or unknown exposure to asbestos. The two female patients were in the unknown exposure category. The fibre concentrations in the patients' lung tissue ranged from less than 0.1 million to 370 million fibres (f) per g dry tissue. Concentrations of over one million f per g dry tissue were found in 15 patients (65%). The lung fibre concentrations of all nine male office workers analysed for reference were less than one million f per g dry tissue. Seventy eight per cent of the patients with mesothelioma had at least possible exposure according to their history of work or concentrations of more than one million f per g dry tissue.
Occupational respiratory disease in the United Kingdom 1989: a report to the British Thoracic Society and the Society of Occupational Medicine by the SWORD project group. S.K. Meredith, V.M. Taylor, J.C. McDonald. 1991;48(5):292-8. PubMed · Publisher · Free full text

Abstract

A voluntary scheme for the surveillance of work related and occupational respiratory disease (SWORD) was established in January 1989 with help from the British Thoracic Society and the Society of Occupational Medicine and support from the Health and Safety Executive. Three hundred and fifty four chest physicians representing 90% of the chest clinics in the United Kingdom and 361 occupational physicians submit reports regularly of newly diagnosed cases of work related respiratory illness with information on age, sex, residence, occupation, and suspected causal agent. In 1989 2101 cases were notified, of which frequent diagnoses were asthma (26%), mesothelioma (16%), pneumoconiosis (15%), benign pleural disease (11%), and allergic alveolitis (6%). Incidence rates calculated against denominators from the Labour Force Survey showed very large differences between occupational groups, especially for asthma and asbestos related diseases. Substantial regional variation in the incidence of asthma was not explained by the geographical distribution of high risk industries and was probably due to differing levels of ascertainment. The results imply that the true frequency of acute occupational respiratory disease in the United Kingdom may have been three times greater than that reported.
On talc, tremolite, and tergiversation. A.M. Langer, R.P. Nolan, J. Addison. 1991;48(5):359-60. Comment · Letter PubMed · Publisher · Free full text
On talc, tremolite, and tergiversation. Ter-gi-ver-sate: 2: to use subterfuges. B.W. Case. 1991;48(5):357-9. Comment · Letter PubMed · Publisher · Free full text

Summary

In this letter, Case responded to an article by Reger and Morgan (1990), which he said read the literature selectively in trying to show that "non-asbestiform" tremolite is not hazardous. He posed three questions: whether non-asbestiform fibres can be unambiguously identified, whether they occur without asbestiform fibres in the same material, and whether they lack biological effects. He answered no to all three. He cited the American Thoracic Society statement that the distinction between cleavage fragments and asbestiform fibres is "in practice extremely murky", and Pooley's description of morphologies as points on a continuum. He argued that microscopic dimensions, not mineralogical definitions, matter for health and regulation, because there is no evidence that cells distinguish fibres of equivalent dimensions. He noted that the US Consumer Product Safety Commission's refusal to ban tremolite-containing play sand was a split decision. He cited evidence that tremolite-actinolite causes lung cancer, mesothelioma and interstitial fibrosis in vermiculite miners. He stressed that pulmonary fibrosis is the most important health effect of talc and non-asbestiform tremolite, citing Merewether's 1933 report of 11 rubber tyre workers. He criticised how animal studies by Stanton et al and by Addison and Davis had been interpreted, noting that one tremolite characterised as fibrous but not asbestiform produced mesothelioma in 70% of animals. He concluded that exempting non-asbestiform fibres from regulation would be folly. The original authors' reply, which disputed these points, is partly included.

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In plain English

This is a letter to the editor, not a research study, and it reports no new data. B W Case wrote it in reply to a 1990 article by Reger and Morgan about "non-asbestiform" tremolite and talc. Case posed three questions: whether non-asbestiform fibres can be clearly identified, whether they occur without asbestiform fibres, and whether they tell us about the biological effects of long, thin, durable fibres. He answered no to all three. He argued that microscopic fibre shape is what counts for health. He said Reger and Morgan left out other researchers' evidence linking tremolite-actinolite to lung cancer, mesothelioma and interstitial fibrosis in vermiculite miners. He also said they left out lung fibrosis from talc, citing Merewether's 1933 report of 11 rubber tyre workers. He noted that one tremolite described as fibrous but not asbestiform produced mesothelioma in 70% of animals in Addison and Davis's work. He accepted that more work is needed. Case concluded that exempting these fibres from regulation "seems folly" until evidence shows they are easily defined, clearly separated from tremolite asbestos at work, and do not cause lung fibrosis or other health effects.

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Prediction of mesothelioma, lung cancer, and asbestosis in former Wittenoom asbestos workers. G. Berry. 1991;48(12):793-802. PubMed · Publisher · Free full text

Abstract

Projections have been made of the number of mesotheliomas, lung cancers, and cases of asbestosis that might occur over the period 1987 to 2020 in former workers at the Wittenoom crocidolite asbestos mine in Western Australia. Predictions were based on the observed mortality to the end of 1986 and modelling of the mesothelioma rate. Elimination of crocidolite from the lungs was included in the model. Between the years 1987 and 2020 it is predicted that between 250 and 680 deaths will occur due to mesothelioma. This wide range is due to uncertainty on the functional form of the relation between mesothelioma rate and time, and insufficient data to estimate the elimination rate of crocidolite from the lungs. The most likely range is the lower half of this total range--that is, between 250 and 500. It is predicted that between 340 and 465 deaths will occur due to lung cancer. About 45% of these deaths would be attributable to exposure to asbestos. It is estimated that currently there are up to 200 cases of undiagnosed asbestosis. Of these about 50 will die of lung cancer or mesothelioma and are therefore also included in the figures above. Up to 60 former workers may develop the first signs of asbestosis in the future but any such cases are likely to progress to more serious disease at a much slower rate than the cases that have already been identified.
Respiratory findings among ironworkers: results from a clinical survey in the New York metropolitan area and identification of health hazards from asbestos in place at work. A. Fischbein, J.C. Luo, S. Rosenfeld, et al. 1991;48(6):404-11. PubMed · Publisher · Free full text

Abstract

Diseases associated with asbestos are prevalent in the construction trades primarily as the result of the previously widespread use of insulation materials containing asbestos in the building industry. Workers in metal related trades, who are employed at construction sites, but who do not routinely use such materials in their work, may also be at risk for asbestos hazards. To assess such risk, a clinical survey was conducted on 869 ironworkers from the New York metropolitan area. A high prevalence of abnormalities on chest radiographs was found. Three hundred and twenty nine (38%) of the examined workers had pleural abnormalities on their chest radiographs consistent with asbestos induced effects. The prevalence of radiographic abnormalities indicating interstitial lung disease was low (7%) as was the prevalence of restrictive pulmonary function impairment (7%). Association was found between forced vital capacity (FVC) and pleural abnormalities on chest radiographs. Although ex-smokers appeared to have the highest prevalence of abnormalities, regression analyses showed that duration of employment in the ironworkers' trade was the most important factor associated with them.
Risk assessment using exposure intensity: an application to vermiculite mining. P.M. Vacek, J.C. McDonald. 1991;48(8):543-7. PubMed · Publisher · Free full text

Abstract

Estimation of exposure-response relations from epidemiological data is complicated by the fact that exposures usually vary in intensity over time. Cumulative exposure indices, which do not separate the effects of intensity and duration, are commonly used to circumvent this problem. In this paper the estimation of relative risk for specific ranges of exposure intensity from such data is considered using existing statistical methods for fitting multivariate relative risk models. This has the advantage that it does not assume that exposure intensity and duration have equivalent effects on risk. It also throws light on the possible existence of a threshold. The procedure was applied to data from a cohort of 406 vermiculite miners to examine the lung cancer risk associated with exposure to fibrous tremolite, which contaminated the vermiculite. The pattern of exposure-response differed substantially from that obtained using a cumulative exposure index to assess risk.
Risk of cancer for arc welders in the Federal Republic of Germany: results of a second follow up (1983-8). N. Becker, J. Chang-Claude, R. Frentzel-Beyme. 1991;48(10):675-83. PubMed · Publisher · Free full text

Abstract

An extended follow up of 1221 chromium and nickel exposed welders in the Federal Republic of Germany confirmed an increased relative risk of 1.6 for all cancers compared with an internal reference group of 1694 turners. In an external comparison an excess of deaths from malignant tumours compared with that expected from the national mortality rates was found (standardised mortality ratio (SMR) = 109), which was clearly related to both time since first exposure and duration of exposure. Mortality from lung cancer was increased among welders (SMR = 113) but also among turners (SMR = 108). The difference remained when the subgroups were compared according to smoking information. A large excess of mesothelioma as a cause of death could be attributed to exposure to asbestos. The significantly increased SMR seen for urogenital tumours and "other or unspecified tumours" showed, however, an inverse relation with time since first exposure. This and other inconsistencies in the analysis by type of welding do not permit conclusive statements. Thus a further extension of follow up seems warranted.
Smoking, exposure to crocidolite, and the incidence of lung cancer and asbestosis. N.H. de Klerk, A.W. Musk, B.K. Armstrong, et al. 1991;48(6):412-7. PubMed · Publisher · Free full text

Abstract

In 1979 all former workers from the Wittenoom asbestos industry who could be traced to an address were sent a questionnaire to determine smoking history. Occupational exposure to crocidolite was known from employment records. Of 2928 questionnaires sent, satisfactory replies were received from 2400 men and 149 women. Eighty per cent of these had smoked at some time and 50% were still smoking. Since that time 40 cases of lung cancer and 66 cases of compensatable asbestosis have occurred in this cohort. The incidence of both lung cancer and asbestosis was greatest in those subjects with the highest levels of exposure to crocidolite and in ex-smokers. Statistical modelling of the joint effects of these exposures on the incidence of each disease indicated that crocidolite exposure multiplied the rates of lung cancer due to smoking and that smoking has no measurable effect on the rates of asbestosis. There was also some evidence that the incidence rate of lung cancer is falling with time.
The discovery of the association between blue asbestos and mesotheliomas and the aftermath. J.C. Wagner. 1991;48(6):399-403. Historical article PubMed · Publisher · Free full text

Abstract

As this is the 30th anniversary of the publication of our paper "Diffuse pleural mesotheliomas and asbestos exposure in the north west Cape Province," and 1 December 1990 is the first anniversary of John Gilson's death, I think it is appropriate to subunit this paper. It covers the background of the discovery of the series of mesotheliomas in the north western region of the Cape Province, and the subsequent publication, which has become the most cited paper in industrial medicine. It was John Gilson who directed the next phase, which substantiated this discovery. He clarified the situation in his summary of the report to the director of the International Agency for Research in Cancer in 1972. This I have quoted in full and have had the temerity to update to 1990. I am sure that many will want to elaborate these views, and I hope that they will submit their opinions to this journal.
The value of anticarcinoembryonic antigen, human milk factor globulin, and antikeratin antibodies in differentiating mesothelioma from lung carcinoma. V.M. Joglekar, D. Oliver, M. Harris. 1991;48(1):34-7. PubMed · Publisher · Free full text

Abstract

Monoclonal anticarcinoembryonic antigen (antiCEA), human milk factor globulin (HMFG2), and antikeratin antibodies were assessed for their value in the differential diagnosis of pleural mesothelioma (53 cases) and carcinoma of the lung (60 cases) in material from necropsies. In 40 of the cases pleural biopsies were also studied in the same manner. AntiCEA was found to be the best discriminating antibody for most types of mesothelioma; HMFG2 was slightly less valuable but a useful additional tool. Antikeratin was the least useful. For both antiCEA and HMFG2 antibodies, however, the proportion of carcinomas staining was smaller than in previous studies and this, combined with the positive staining of some mesotheliomas, reduces the value of the reactions in the individual case. Medical panels adjudicating compensation claims should not use these reactions as the sole criteria in deciding the origin of the tumours in these cases.
Ventilatory function after exposure to various respirable hazards in a population of former coal miners. G.M. Calvert, M. Moore, S.M. Hessl. 1991;48(1):38-40. PubMed · Publisher · Free full text

Abstract

The ventilatory function of 406 male former coal miners who had presented at the Cook County Hospital occupational medicine clinic between January 1976 and April 1987 was studied to determine whether subsequent exposure to respiratory hazards after leaving the coal mines adversely affected lung function. The miners were divided into five exposure groups based on their exposure to respirable hazards. These were coal dust only, coal dust plus asbestos dust, coal dust plus silica dust, coal dust plus another respirable hazard and coal dust plus two other respirable dust exposures. Duration of employment in coal mines, race, smoking history, and mean age were not significantly different between the various exposure groups. No significant difference was found in the per cent of predicted forced expiratory volume in one second (FEV1), per cent of predicted forced vital capacity (FVC), and FEV1/FVC when the coal dust only group was compared with each of the other four exposure groups using ANOVA. Among former coal miners who present for a respiratory disability determination, therefore, exposure to respirable hazards subsequent to employment in coal mines is not associated with a statistically significant deterioration in ventilatory function.
Abnormal pulmonary function associated with diaphragmatic pleural plaques due to exposure to asbestos. K.H. Kilburn, R.H. Warshaw. 1990;47(9):611-4. PubMed · Publisher · Free full text

Abstract

Pulmonary function was measured in 79 men with diaphragmatic pleural plaques (DPP) as the only abnormality characteristic of asbestos disease on chest radiographs. They were selected from 4572 construction and shipyard workers exposed to asbestos. Abnormalities of pulmonary function in 21 non-smokers and 43 current smokers were compared with referent values adjusted for height, age, and duration of cigarette smoking. In the non-smokers, flows (FEV1) FEF75-85 and FEV1/FVC) were reduced and TGV and RV/TGV were raised. Current smokers had similar significant reductions. Thus by contrast with some current opinion that plaques are "an index only of past asbestos exposure," workers with plaques, even limited to the diaphragm, have functional impairment typical of pulmonary asbestosis. This suggests that they have pulmonary asbestosis, which is below the threshold of radiographic recognition.
Alterations in laryngeal mucosa after exposure to asbestos. D. Davies. 1990;47(12):844. Comment · Letter PubMed · Publisher · Free full text
An update of cancer mortality among chrysotile asbestos miners in Balangero, northern Italy. G. Piolatto, E. Negri, C. La Vecchia, et al. 1990;47(12):810-4. PubMed · Publisher · Free full text

Abstract

The mortality experience of a cohort of chrysotile miners employed since 1946 in Balangero, northern Italy was updated to the end of 1987 giving a total of 427 deaths out of 27,010 man-years at risk. A substantial excess mortality for all causes (standardised mortality ratio (SMR) = 149) was found, mainly because of high rates for some alcohol related deaths (hepatic cirrhosis, accidents). For mortality from cancer, however, the number of observed deaths (82) was close to that expected (76.2). The SMR was raised for oral cancer (SMR 231 based on six deaths), cancer of the larynx (SMR 267 based on eight deaths), and pleura (SMR 667 based on two deaths), although the excess only reached statistical significance for cancer of the larynx. Rates were not increased for lung, stomach, or any other type of cancer. No consistent association was seen with duration or cumulative dust exposure (fibre-years) for oral cancer, but the greatest risks for laryngeal and pleural cancer were in the highest category of duration and degree of exposure to fibres. Although part of the excess mortality from laryngeal cancer is probably attributable to high alcohol consumption in this group of workers, the data suggest that exposure to chrysotile asbestos (or to the fibre balangeroite that accounts for 0.2-0.5% of total mass in the mine) is associated with some, however moderate, excess risk of laryngeal cancer and pleural mesothelioma. The absence of excess mortality from lung cancer in this cohort is difficult to interpret.
Asbestos bodies in bronchoalveolar lavage fluids of brake lining and asbestos cement workers. P. Dumortier, P. De Vuyst, P. Strauss, et al. 1990;47(2):91-8. PubMed · Publisher · Free full text

Abstract

Asbestos body (AB) concentrations in bronchoalveolar lavage samples of 15 brake lining (BL) workers exposed only to chrysotile have been determined and compared with those from 44 asbestos cement (AC) workers extensively exposed to amphiboles. The mean AB concentrations (263 +/- 802 and 842 +/- 2086 AB/ml respectively) for those groups did not differ significantly but were much higher than those found in control groups. Analytical electron microscopy of asbestos body cores showed that in the BL group 95.6% were chrysotile fibres whereas in the AC group amphiboles accounted for 93.1%. The size characteristics of the central fibres differed for chrysotile and amphibole AB, the former being shorter and thinner. Examination of repeated bronchoalveolar lavage samples showed that the mechanisms of clearance of chrysotile fibres do not affect AB concentration for at least 10 months after cessation of exposure. It thus appears that routine counting of ABs in BAL allows the assessment of current or recent occupational exposures to asbestos. Exposures to chrysotile lead to AB concentrations comparable with those encountered in exposures to amphiboles.
Asbestos related abnormalities among United States merchant marine seamen. P.J. Barrett. 1990;47(12):844-5. Letter · Comment PubMed · Publisher · Free full text
Asbestos related health hazards among power plant workers. Y. Lerman, A. Finkelstein, Y. Levo, et al. 1990;47(4):281-2. Case report PubMed · Publisher · Free full text
Asbestos: a chronology of its origins and health effects. R. Murray. 1990;47(6):361-5. Historical article PubMed · Publisher · Free full text

Abstract

The emotionalised subject of asbestos is treated in chronological terms: how the "magic mineral" known in ancient times in Europe and Asia became in the late nineteenth century an important industrial resource of particular interest to the navies of the world; and how its malign effects gradually became apparent during the present century. The media have made asbestos a notorious villain, but it still has properties and applications useful to society if they are properly controlled in the same way as other industrial hazards. One important application is the manufacture of asbestos cement pipes which are a convenient and cheap method of providing water supplies and sewage disposal for developing countries. An appeal is made for prudence and not hysteria in relation to the use of mineral fibres of all types.
Asbestos: a chronology of its origins and health effects. L. Arblaster, E. Renvoize, P. Hatton, et al. 1990;47(11):790. Historical article · Letter PubMed · Publisher · Free full text
Asbestos: a chronology of its origins and health effects. M. Huncharek. 1990;47(12):845-6. Comment · Letter PubMed · Publisher · Free full text
Asbestotic radiological abnormalities among United States merchant marine seamen. I.J. Selikoff, R. Lilis, G. Levin. 1990;47(5):292-7. PubMed · Publisher · Free full text

Abstract

There has been limited information concerning the prevalence of radiologically evident parenchymal and pleural fibrosis consistent with prior exposure to asbestos among merchant marine seamen, despite the wide use of asbestos in ship construction until the late 1970s and subsequent exposure of seamen to the asbestos that had been installed. A total of 3324 chest radiographs (1985-7) of long term United States seamen were reviewed. One third (34.8%) had parenchymal or pleural abnormalities, or both (ILO classification); pleural changes were predominant. Abnormalities increased with longer duration from onset of shipboard exposure (as defined by first year at sea). The prevalence of asbestotic changes was greater among seamen who had served in the engine department (391/420; 42.5%) compared with seamen in other departments, including deck (301/820; 36.6%), steward (278/981; 28.4%), or with service in multiple departments (167/541; 30.9%). Since many vessels, particularly those built before 1978, contain asbestos materials, appropriate engineering controls (including complete removal, if possible) are required as well as appropriate medical surveillance for those who served aboard such ships.
Cancer mortality and exposure to crocidolite. A. Rogers. 1990;47(4):286. Letter PubMed · Publisher · Free full text

Summary

This letter responded to papers by de Klerk et al (1988 and 1989) that modelled the relation between asbestos disease risk and airborne exposure at the Wittenoom crocidolite mine and mill. Rogers argued that these models relied heavily on a single, relatively short occupational hygiene survey by Major. When Major retired in 1984 he gave Rogers his long running thermal precipitator slides, and Rogers reassessed some of them with modern light and electron microscopy. He reported that the estimates made about 20 years earlier had underestimated exposure considerably, by up to an order of magnitude. A figure of 27 f/ml could become closer to 200 f/ml under modern resolution criteria and counting rules. The highest recount indicated about 300 f/ml longer than 5 µm and a further 800 f/ml shorter than 5 µm. Samples from the general area outside the plant showed up to 2 f/ml longer than 5 µm. Rogers noted that de Klerk et al had applied estimates for a few occupations in one mill to 87 job classifications in another, dustier mill that closed in 1957. He concluded that their quantitative data could not be supported. In reply, the authors stated that their dose-response estimates relied mainly on internal comparisons, on the ranking of jobs and on duration of exposure. They said the data were the only estimates available, and that Major had helped rank the occupations. They said they would use Rogers' results once these were published and peer reviewed.

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Cancer mortality in a northern Italian cohort of rubber workers. A. Fischbein. 1990;47(1):71-2. Comment · Letter PubMed · Publisher · Free full text
Chronic pleuritic pain in four patients with asbestos induced pleural fibrosis. A. Miller. 1990;47(3):147-53. Case report PubMed · Publisher · Free full text

Abstract

Four patients occupationally exposed to asbestos, each suffering at least eight years of disabling, persistent, and often bilateral pleuritic pain are described. Radiographic evidence of pleural disease ranged from plaques seen only on computed tomography to typical bilateral plaques or diffuse thickening to extensive diffuse and circumscribed pleural fibrosis and calcification. There was no history or evidence of acute pleuritis or pleural effusion in three patients. Intermittent pleural friction rubs have been present in all four; one patient showed pleural uptake of gallium-67. Extensive workups including repeated pulmonary ventilation-perfusion scans and cardiac catheterisation have not yielded other diagnoses to explain the pain. It is proposed that persistent pleuritic pain be added to the manifestations of benign asbestos induced pleural disease.
Comparing biological effects of mineral fibres. J.M. Meijers. 1990;47(4):286-7. Letter PubMed · Publisher · Free full text
Comparison of chest radiograph reading methods for assessing progress of pneumoconiosis over 10 years in Wittenoom crocidolite workers. N.H. de Klerk, A.W. Musk, A. James, et al. 1990;47(2):127-31. Randomized trial PubMed · Publisher · Free full text

Abstract

Thirty three pairs of chest radiographs taken up to 10 years apart were obtained for 33 subjects suffering from asbestosis who had applied for compensation to the Pneumoconiosis Medical Board of Western Australia. Multiple films from the period before the first radiograph in each pair, from the intervening period between the two, and from the period subsequent to the second radiograph were also available and all films were read by two independent readers according to the 1980 ILO classification of pneumoconiosis. Films were read twice as side by side pairs ten years apart, twice as two separate randomly ordered films ten years apart, and once as part of the full series of all available chest radiographs on each subject to assess which method provided the best consistency (between reader variation) and repeatability (within reader variation). Judging by consistency, the full series method performed as well as either of the other methods when assessing radiographic changes and significantly better when assessing the level of profusion of small opacities. There was little to choose between the other two methods either judging by consistency or repeatability, which could not be estimated for the full series method. Use of all available films for a subject is recommended for assessing single films, as in a prevalence study, as well as for documenting change in a longitudinal study.
Comparison of fibre types and size distributions in lung tissues of paraoccupational and occupational cases of malignant mesothelioma. A.R. Gibbs, D.M. Griffiths, F.D. Pooley, et al. 1990;47(9):621-6. PubMed · Publisher · Free full text

Abstract

The results of analysis of mineral fibres in lung tissues from 10 paraoccupational cases of malignant mesothelioma were compared with analysis obtained from seven cases of malignant mesotheliomas that had developed in gas mask workers. Nine of the paraoccupational cases were considered to have developed their tumours because of exposure to asbestos on their husbands' working clothes and one cancer developed in the daughter of a man who had died of asbestosis. The gas mask workers had direct exposure to asbestos while working in a factory that produced military gas masks. The results of mineral fibre analysis in the paraoccupational cases were variable; six showed high crocidolite concentrations, seven raised amosite concentrations and two normal concentrations of all types of asbestos fibre measured. Chrysotile was raised in one case but crocidolite and amosite were also increased. The gas mask workers showed a consistent pattern with high crocidolite concentrations and normal or low concentrations of chrysotile and amosite. Fibre lengths for chrysotile were similar in both groups and predominantly less than 5 microns. Crocidolite fibres tended to be longer in the gas mask workers than in the paraoccupational group and longer than chrysotile in both groups. Amosite fibres tended to be more variable in width than those of chrysotile or crocidolite.
Individual asbestos exposure: smoking and mortality--a cohort study in the asbestos cement industry. M. Neuberger, M. Kundi. 1990;47(9):615-20. PubMed · Publisher · Free full text

Abstract

A historical prospective cohort study comprised all persons employed from 1950 to 1981 for at least three years in the oldest asbestos cement factory in the world. From 2816 persons eligible for the study, record based estimates and measurements of dust and fibres and histories of smoking based on interviews were used to calculate individual exposures over time. After observation of 51,218 person-years and registration of 540 deaths, underlying causes of death for this cohort were compared with those for the regional population on the basis of death certificates. Deaths from lung cancer in asbestos cement workers were higher (standard mortality ratio (SMR) 1.7), but after adjustment for age and sex specific smoking habits this was not significant (SMR 1.04). The study had a probability of greater than 92% of detecting a smoking adjusted SMR of 1.5 or more. Using the best available evidence (including necropsy records) 52 deaths were assigned to lung cancer and five to mesothelioma. Life table analyses confirmed the predominant influence of smoking on lung cancer. Mesothelioma was associated with the use of crocidolite in pipe production. From present working conditions with much lower concentrations of chrysotile and no crocidolite no more occupational cancers are expected in the asbestos cement industry.
Laryngeal cancer and asbestos. F.D. Liddell. 1990;47(5):289-91. Review PubMed · Publisher · Free full text

Summary

In this editorial, the author reviewed the evidence on whether exposure to asbestos causes cancer of the larynx. He traced the hypothesis to a cohort of some 1500 employees of an asbestos company followed up to mid-1960, in which 1 laryngeal cancer death was observed against 0.38 expected. He discussed the limitations of cohort and case-referent studies for this rare cancer, and the strong effects of smoking and alcohol. He disputed earlier reviews that had judged asbestos a risk factor. He noted that the early Liverpool and Toronto case-referent studies had methodological flaws. The only study with exposure histories taken blind, in London hospitals, gave an asbestos relative risk substantially below unity. The Quebec chrysotile cohort, with yearly exposure measures for 11 000 subjects, showed a slightly negative relation with cumulative exposure. He found the case-referent results mutually inconsistent. The cohort studies did not indicate a major excess of laryngeal cancer deaths. In 25 male cohorts that did not mention laryngeal cancer, he estimated that more than 20 deaths might have been expected. In his opinion the evidence definitely failed to satisfy Bradford Hill's criteria for causation. He judged that any absolute risk attributable to asbestos must be extremely small and that excesses appeared quite unlikely with chrysotile. He noted that the UK Industrial Injuries Advisory Council had recommended against adding laryngeal cancer to the prescribed diseases for asbestos-exposed occupations.

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Malignant mesothelioma: clustering in a family producing asbestos cement in their home. K.E. Otte, T.I. Sigsgaard, J. Kjaerulff. 1990;47(1):10-3. Case report PubMed · Publisher · Free full text

Abstract

In a family with a remarkable aggregation of malignant mesothelioma the father, mother, and a son all died of the condition, whereas two other sons and a daughter were unaffected. From 1944 to 1961 the family produced a material that was used to fix screws in drilled holes and consisted of amosite, gypsum, and sand. It was produced in the basement of their villa and was described as being a dusty job. The father died in 1984 aged 74, the son in 1985 aged 45, and the mother in 1987 aged 79. It is concluded that there is a high risk of malignant mesothelioma after massive exposure to amosite and the risk and latency period are independent of age during the exposure.
Mineral fibres, fibrosis, and asbestos bodies in lung tissue from deceased asbestos cement workers. M. Albin, L. Johansson, F.D. Pooley, et al. 1990;47(11):767-74. PubMed · Publisher · Free full text

Abstract

Lung tissue from 76 deceased asbestos cement workers (seven with mesothelioma) exposed to chrysotile asbestos and small amounts of amphiboles, has been studied by transmission electron microscopy, together with lung tissue from 96 controls. The exposed workers with mesothelioma had a significantly higher total content of asbestos fibre in the lungs than those without mesothelioma, who in turn, had higher concentrations than the controls (medians 189, 50, and 29 x 10(6) fibres/g (f/g]. Chrysotile was the major type of fibre. The differences were most pronounced for the amphibole fibres (62, 4.7, and 0.15 f/g), especially crocidolite (54, 1.8 and less than 0.001 f/g), but were evident also for tremolite (2.9, less than 0.001, and less than 0.001 f/g) and anthophyllite (1.7, less than 0.001, and less than 0.001 f/g). For amosite, there was no statistically significant difference between lungs from workers with and without mesothelioma; the lungs of workers had, however, higher concentrations than the controls. Strong correlations were found between duration of exposure and content of amphibole fibres in the lungs. Asbestos bodies, counted by light microscopy, were significantly correlated with the amphibole but not with the chrysotile contents. Fibrosis was correlated with the tremolite but not the chrysotile content in lungs from both exposed workers and controls. Overall, similar results were obtained using fibre counts and estimates of mass.
Mortality among United Kingdom servicemen who served abroad in the 1950s and 1960s. S.C. Darby, C.R. Muirhead, R. Doll, et al. 1990;47(12):793-804. PubMed · Publisher · Free full text

Abstract

The Registrar General's decennial supplements on occupational mortality provide only limited information on mortality in the armed forces in the United Kingdom. Mortality has therefore been studied among a group of 30,619 United Kingdom servicemen who served abroad in tropical or desert areas in the 1950s and 1960s, and who remained in the services for a total of at least five years. Mortality from all causes of death, all neoplasms, and all other known non-violent causes was lower than that expected from rates for all men in England and Wales, whereas mortality from accidents and violence was raised. These differences remained after adjustment for social class, affected both officers and other ranks, and had not disappeared even after the men had been followed up for at least 20 years. When mortality from 20 specific cancers and 10 other disease groups was examined there were significant excesses for cancers of the oesophagus (standardised mortality ratio (SMR) = 146; p = 0.03) and prostate (SMR = 156; p = 0.03), and significant deficits for cancers of the lung (SMR = 73; p less than 0.001), stomach (SMR = 66; p = 0.002), bladder (SMR = 53; p = 0.02), other specified neoplasms (SMR = 48; p = 0.001), coronary heart disease (SMR = 76; p less than 0.001), bronchitis, emphysema, and chronic obstructive lung disease (SMR = 42; p less than 0.001), and for five further groups of diseases unrelated to smoking or alcohol. Examination of mortality in each of the three services separately identified two specific hazards in the Royal Navy; seven deaths from mesothelioma occurred compared with less than 2.06 expected (p less than 0.005), and there was also an excess of neoplasms and of other diseases associated with alcohol (SMRs of 181 and 229; p = 0.002 and less than 0.001). Mortality from smoking related diseases other than those associated with alcohol was low in all three services, particularly among officers.
Mortality and cancer incidence in chloralkali workers exposed to inorganic mercury. L. Barregård, G. Sällsten, B. Järvholm. 1990;47(2):99-104. PubMed · Free full text

Abstract

Mortality and cancer incidence were studied in men exposed to inorganic mercury at eight Swedish chloralkali plants where individual biological monitoring data were available. Urinary mercury excretion has declined from about 200 micrograms/l during the 1950s to less than 50 micrograms/l today. These workers had also been exposed to chlorine and static magnetic fields. At some of the plants there had been a low degree of exposure to asbestos. In total, 1190 men had been monitored for at least one year between 1946 and 1984. Their mortality and cancer incidence were compared with those of the general male population. Mortality from all causes was not significantly increased (rate ratio = 1.1). Cardiovascular mortality was slightly increased (rate ratio = 1.3; 95% CI 1.0-1.5) for no known reason. An excess of lung tumours was seen (rate ratio = 2.0; 95% CI 1.0-3.8), possibly caused by previous exposure to asbestos. Mortality from non-malignant diseases of the brain and the kidneys, the main target organs in mercury poisoning, was not increased, nor was the incidence of brain tumours (3 observed v 1.1 expected) or kidney tumours (3 observed v 1.9 expected).
Mortality and cancer morbidity in cohorts of asbestos cement workers and referents. M. Albin, K. Jakobsson, R. Attewell, et al. 1990;47(9):602-10. PubMed · Publisher · Free full text

Abstract

Total and cause specific mortality and cancer morbidity were studied among 1929 asbestos cement workers with an estimated median cumulative exposure of 2.3 fibre (f)-years/ml (median intensity 1.2 f/ml, predominantly chrysotile). A local reference cohort of 1233 industrial workers and non-case referents from the exposed cohort were used for comparisons. The risk for pleural mesothelioma was significantly increased (13 cases out of 592 deaths in workers with at least 20 years latency). No case of peritoneal mesothelioma was found. A significant dose response relation was found for cumulative exposure 40 years or more before the diagnosis, with a multiplicative relative risk (RR) of 1.9 for each f-year/ml. No relation was found with duration of exposure when latency was accounted for. There was a significant overrisk in non-malignant respiratory disease (RR = 2.6). The overall risks for respiratory cancer, excluding mesothelioma, and for gastrointestinal cancer were not significantly increased. Surprisingly, colorectal cancer displayed a clear relation with cumulative dose, with an estimated increase of 1.6% in the incidence density ratio for each f-year/ml (but not with duration of exposure).
On talc, tremolite, and tergiversation. R. Reger, W.K. Morgan. 1990;47(8):505-7. Review PubMed · Publisher · Free full text

Summary

In this editorial, the authors considered whether non-asbestiform anthophyllite, tremolite and actinolite should be regulated in the same way as asbestos. The 1986 US Occupational Safety and Health Administration standard, which set a limit of 0.2 f/ml, treated them as asbestos. The authors reviewed animal experiments in which fibres were injected into the pleural or peritoneal cavities of rats or hamsters. In these, asbestiform tremolite produced mesotheliomas or other tumours, but non-asbestiform tremolite did not. They reviewed mortality studies of gold and taconite miners exposed to cummingtonite-grunerite, the non-asbestiform analogue of amosite, which showed no excess or trend for respiratory cancer. They then reviewed studies of talc miners and millers in upstate New York. Early studies reported excess lung cancer, including 12 of 108 deaths in one study and nine deaths (SMR 270) among 398 workers in another, but lacked smoking histories. In the latter study, five of the lung cancer cases had worked at the facility for one year or less. A later update included a nested case-control study of 22 lung cancer cases, each matched to three controls. It found a strong association with cigarette smoking and an apparent inverse relation between exposure and lung cancer. The authors also noted that US consumer product and mine safety agencies distinguished between the two mineral forms. They concluded that the overall results argued convincingly against a causal connection between lung cancer and non-asbestiform tremolite. They added that animal studies suggested any risk from non-asbestiform amphiboles was markedly less than that from asbestos.

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Pleural lesions in crocidolite workers from Western Australia. G. Hillerdal, A.W. Musk. 1990;47(11):782-3. PubMed · Publisher · Free full text
Pleural mesothelioma in a non-shipyard electrician. M. Huncharek, J. Muscat. 1990;47(1):68. Case report PubMed · Publisher · Free full text

Summary

The authors described a case of pleural mesothelioma in an electrician who had not worked in shipyards. They noted that the risk of mesothelioma among non-shipyard electricians had received little attention. The patient was a 38 year old white man admitted to hospital in January 1974 with left sided pleuritic chest pain and effusion. He had had two earlier episodes of pleurisy with effusion, of unknown cause, in March 1972 and November 1973. He had a 45 pack-year smoking history. At thoracotomy in April 1974, nodules were removed from the diaphragm, left lung and pleura, and pathology showed papillary masses of mesothelial cells infiltrating skeletal muscle. The report states that the tumour was 'tested' with thio-tepa and BCG. He was essentially without symptoms until June 1982, when needle aspiration produced malignant cells consistent with mesothelioma, and he was given radiotherapy and adriamycin. In August 1983 the disease had progressed markedly in the left lung. He was last known to be alive in April 1984. He had worked as an electrician from 1959 until 1974. This work included buildings where acoustic insulation was sprayed on, locomotives whose boilers were being insulated, and, from 1971, airport maintenance work with old asbestos insulation and fireproofing, which coworkers often removed in his presence. The authors concluded that the case suggested a possible risk of asbestos related mesothelioma in this occupational group and that increased surveillance may be justified.

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Relation between asbestosis and bronchial cancer in amphibole asbestos miners. R.M. Rudd. 1990;47(3):215-6. Comment · Letter PubMed · Publisher · Free full text

Summary

In a letter, Rudd commented on a 1989 paper by Sluis-Cremer and Bezuidenhout on the relation between asbestosis and bronchial cancer in amphibole asbestos miners. He noted that the paper analysed dose of asbestos only after allowing for asbestosis grade. Because asbestosis is itself dose related, he argued that much of the effect of dose had already been accounted for. Years of exposure nevertheless still had a significant effect, which he considered consistent with dose of asbestos, rather than asbestosis, being the major determinant of cancer risk. He suggested entering the dose measures before asbestosis grade, and comparing subjects with and without asbestosis matched for dose. He also raised possible sources of bias. Necropsies were done in a minority of deaths and the selection criteria were not stated. It was not indicated whether asbestosis was assessed without knowledge of cancer status. The group without asbestosis may have had relatively slight exposure. In reply, Sluis-Cremer and Bezuidenhout reported that, after adjusting for smoking and age and entering the dose measures before asbestosis grade, asbestosis still emerged as a significant risk factor. They also matched each of 35 cases to two to four referents with years of exposure within 20%, giving 157 subjects. Conditional logistic regression adjusting for age and smoking gave an odds ratio for asbestosis of 3.4 (p = 0.03; 95% CI 1.1-10.46). The available text of the reply ends partway through.

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Role of manmade mineral fibres in the causation of cancer. P.E. Enterline. 1990;47(3):145-6. PubMed · Publisher · Free full text

Summary

This editorial considered whether manmade mineral fibres (MMMF) cause cancer. It drew on two large epidemiological studies, one in the United States and one in Europe, of over 40 000 MMMF production and maintenance workers. Twenty years or more after first exposure, rock/slag wool workers had a 30% (United States) and 40% (Europe) increase in respiratory cancer. Glass wool workers had an excess of roughly 10%, and glass filament workers had none. The author argued that the estimated fibre exposures were too low to explain these excesses, even by comparison with asbestos. Animal studies had indicated that, fibre for fibre, MMMF were much less carcinogenic than asbestos. Asbestos had been used in four of six United States rock/slag wool plants and in four European plants, but these plants showed no greater excess than plants that did not use it. Both studies linked the excess to the use of slag. Slag plants had about double the expected respiratory or lung cancer deaths. Plants using slag from copper smelters, believed or known to be contaminated with arsenic, had two and a half (Europe) and three and a half (United States) times the expected deaths. The author concluded that fibres probably did not play the major part in the excess among slag wool workers. He considered a proposed US Environmental Protection Agency classification of rock/slag wool as more hazardous than glass wool probably misleading. He judged that ordinary MMMF carry some small cancer hazard, much less than that of asbestos.

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Silica exposure, silicosis, and lung cancer: a necropsy study. P.A. Hessel, G.K. Sluis-Cremer, E. Hnizdo. 1990;47(1):4-9. PubMed · Publisher · Free full text

Abstract

Recent studies of the association between lung cancer and silicosis and silica dust have been inconclusive; some showing positive association and some showing none. The present study matched 231 cases of lung cancer with 318 controls by year of birth. Subjects were selected from the necropsy records of the National Centre for Occupational Health. Data on intensity and duration of exposure to silica dust were obtained from personnel records. Presence or absence of lung cancer and the presence and severity of silicosis of the parenchyma, pleura, and hilar glands were documented from necropsy reports. Smoking data were abstracted from records of routine examinations. No case-control differences were noted for any of the exposure indicators including cumulative dust exposure, total dusty shifts, weighted average intensity of exposure, total underground shifts, and shifts in high dust. Similarly, no association was found between lung cancer and the presence or severity of silicosis and any site. Stratified analyses showed neither significant nor suggestive trends when case-control comparisons for silicosis were examined by level of dust exposure or smoking. Reasons for disparity between these results and those of some other studies may include concomitant exposures to radon daughters, asbestos, diesel emissions, and cigarette smoking; idiosyncracies of the compensation process; and the possibility of a threshold in the relation(s).
The distribution of amosite asbestos in the periphery of the normal human lung. A. Churg. 1990;47(10):677-81. PubMed · Publisher · Free full text

Abstract

Although theoretical models and experiments on animals exist that predict the distribution of asbestos fibres in the lung, there are few studies in man that relate to this question and they have generated contradictory results. To examine this distribution analytical electron microscopy was employed to determine the amosite fibre concentration, size, surface area, and mass in 29 circumferential sites around the periphery of a mid-sagittal slice from nine morphologically normal left lungs of heavily exposed shipyard workers and insulators. Fibre concentrations were heaviest in the apical segment of the upper lobe, and low concentrations were seen in the posterior basal portion of the lower lobe. Overall, the upper lung zones had significantly greater concentrations than the lower lung zones. Fibre length was shortest in the anterior portion of the upper lobe, greater in the lingula, and greatest in the posterior basal portion of the lower lobe; fibre length overall was significantly greater in the lower compared with the upper zones. Aspect ratio followed a similar pattern. Distinct geographic runs of high or low concentrations and long or short lengths and aspect ratios were present. No consistent distribution patterns for fibre width, surface area, or mass were found. It is concluded that: (1) in the periphery of the normal lung, concentration of amosite fibres is greatest in the apex and least in the peripheral lower lobe. This distribution is the opposite of what would be expected from the known distribution of asbestosis (peripheral lower zone); nor does it correlate with bronchial pathlength or branch number, contrary to predictions from studies on animals and theoretical models; (2) fibre length and related parameters show a distribution opposite to that of fibre concentration and again do not correlate with theoretical predictions.
Trends and geographical patterns of pleural mesotheliomas in the Netherlands 1970-87. J.M. Meijers, H.T. Planteydt, J.J. Slangen, et al. 1990;47(11):775-81. PubMed · Publisher · Free full text

Abstract

The sex and age related trends and geographical distribution of asbestos related mortality from pleural mesothelioma in the Netherlands between 1970 and 1987 were investigated. Deaths from pleural malignancies recorded by the Dutch Central Bureau of Statistics (CBS) were used and death rates were age adjusted per year by the indirect method. Standardised mortality ratios (SMRs) were computed for 43 regions over the period 1979-86. For men, total mortality increased from 10.8 per million in the period 1970-8 to 20.9 per million during 1979-87. The highest mortality occurred in the group aged between 65 and 74 with 147.7 per million in 1987. The death rate for the group aged between 55 and 64 was 96.5 per million in 1987. For women, total death rates for pleural mesothelioma showed a moderate increase from 2.5 per million in the period 1970-8 to 3.6 per million during 1979-87. The highest mortality occurred in the group aged over 65, fluctuating around 10-15 per million. For men and women under 45 mortality was very low and presented no upward trend. The geographical distribution over the country for the period 1979-86 showed a pattern with a clear concentration of deaths from mesothelioma in men, in conurbations with many harbours, shipyards, and heavy industry near the river mouths and along the North Sea Coast.

1980s

A mortality study of workers manufacturing friction materials: 1941-86. M.L. Newhouse, K.R. Sullivan. 1989;46(3):176-9. PubMed · Publisher · Free full text

Abstract

The mortality of workers employed at a factory producing friction materials has been studied from 1941 to 1986, extending a previous study by seven years. Apart from two periods before 1944, when crocidolite asbestos was used on one particular contract, only chrysotile asbestos has been used. Thirteen deaths were attributed to mesothelioma and of these, 11 were of subjects who had known contact with crocidolite asbestos. Of the remaining two, in one instance the diagnosis is uncertain and in the other the occupational history of the subject is not well established. There was no excess of deaths from lung cancer or other asbestos related tumours, or from chronic respiratory disease. After 1950 hygienic control was progressively improved and from 1970 levels of asbestos in air have not exceeded 0.5-1.0 f/ml. It is concluded that with good environmental control chrysotile asbestos may be used in manufacture without causing excess mortality.
Alterations in the laryngeal mucosa after exposure to asbestos. V. Kambic, Z. Radsel, N. Gale. 1989;46(10):717-23. PubMed · Publisher · Free full text

Abstract

The laryngeal mucosa of 195 workers in an asbestos cement factory (Salonit Anhovo, Yugoslavia) and in a control group was examined. The factory manufactures asbestos cement products containing about 13% of asbestos (8% amosite, 12% crocidolite, and 80% chrysotile) of different provenance. Alterations in the laryngeal mucosa were more frequent in the factory workers than in the control group. The changes, mostly consistent with chronic laryngitis, were closely related to the degree of workplace pollution and less so to the duration of employment Ten workers exhibiting the most severe clinical changes underwent biopsy, the results of which showed histomorphological changes characteristic of hyperplastic chronic laryngitis. Four tissue specimens were examined also by scanning electron microscopy and in three of them asbestos fibres were found on the epithelial surface. No case of laryngeal carcinoma was identified. On the basis of our results it is thought that asbestos related changes of the larynx should receive more attention and that the use of the term "laryngeal asbestosis" is justified. The clinical picture is non-specific but in view of their frequency such changes should be considered a consequence of exposure to asbestos.
Antibody producing cells in the spleens of mice treated with pathogenic mineral dust. S. Szymaniec, D.M. Brown, M. Chladzynska, et al. 1989;46(10):724-8. PubMed · Publisher · Free full text

Abstract

Experiments were carried out to assess the effect of intraperitoneal injection of the mineral dusts, titanium dioxide, quartz, or asbestos, on splenic lymphocyte antibody forming cells in immunised mice. Titanium dioxide and quartz caused similar, about one third, reductions in plaque forming cells; asbestos caused substantial reduction to about a quarter of the number found in control spleens. The inhibition of antibody forming cells in the spleen found with chrysotile was dose dependent and both chrysotile and crocidolite asbestos were similar in activity. Systemic immunomodulation after local deposition of mineral dust may be important to the development of disease.
Asbestosis occurring after brief inhalational exposure: usefulness of bronchoalveolar lavage in diagnosis. R.G. Barbers, J.L. Abraham. 1989;46(2):106-10. Case report PubMed · Publisher · Free full text

Abstract

A case of clinically and radiologically typical asbestosis manifesting in a 55 year old man occurred 36 years after a brief exposure period of less than one year. A transbronchial lung biopsy was performed but the samples were considered non-diagnostic. The diagnosis was supported by the use of bronchoalveolar lavage to obtain alveolar samples and scanning electron microscopy-energy dispersive x ray analysis of fibres found in the bronchoalveolar lavage fluid which showed a predominance of amosite.
Cancer mortality in relation to measures of occupational exposure to crocidolite at Wittenoom Gorge in Western Australia. N.H. de Klerk, B.K. Armstrong, A.W. Musk, et al. 1989;46(8):529-36. PubMed · Publisher · Free full text

Abstract

The separate and combined effects of duration and intensity of exposure to crocidolite on mortality from lung cancer, malignant mesothelioma, and stomach cancer were examined in 6506 male former crocidolite miners and millers at Wittenoom Gorge, Western Australia. Each subject who had died from lung cancer (92), mesothelioma (31), or stomach cancer (17) was matched with up to 20 control subjects of the same age who were not known to have died before the index subject. Relations of dose and time of exposure to crocidolite to risk of death were modelled by conditional logistic regression. For lung cancer, the best fitting multiplicative model was one which estimated a relative risk (RR) of 1.12 (95% CI 1.04-1.20) per year of exposure and 1.01 (95% CI 1.00-1.01) per fibre/ml. This was statistically indistinguishable from an additive model showing an increase in RR of 0.01045 (95% CI 0.008-0.020) per f/ml year. For mesothelioma the best fitting model appeared to be one estimating a RR of 24.9 (95% CI 3.51-1.77) per log year since first exposed and a RR of 10.5 (95% CI 3.12-35.1) if exposed for longer than six months. This was not distinguishable statistically from a model that showed mortality increasing as the fourth power of time since first exposed less the fourth power of time since last exposed. The effect of intensity of exposure on the RR for mesothelioma was only slight. There was no consistent effect of any measure of exposure to crocidolite on death from stomach cancer.
Comparing biological effects of mineral fibres. J. Dunnigan. 1989;46(10):681-2. Review PubMed · Publisher · Free full text
Correlation between fibre content of lung and disease in east London asbestos factory workers. R.M. Rudd. 1989;46(5):358-9. Comment · Letter PubMed · Publisher · Free full text
Disability, mortality, and incidence of cancer among Geneva painters and electricians: a historical prospective study. E. Gubéran, M. Usel, L. Raymond, et al. 1989;46(1):16-23. PubMed · Publisher · Free full text

Abstract

The 1916 painters and the 1948 electricians who resided in the Canton of Geneva at the time of the 1970 census were identified and followed up to 1984. During the study period 121 disability pensions were awarded to painters and 59 to electricians. Age standardised incidence of disability per 1000 man-years at risk was higher among painters than among electricians for all neuropsychiatric causes (1.23/1000 and 0.68/1000, respectively) and for all other causes (5.50/1000 and 3.41/1000, respectively). No case of presenile dementia was diagnosed among painters. There was inadequate evidence to indicate that the higher risk of neuropsychiatric disability for painters might have been due to their occupational exposure to organic solvents. A possible toxic effect of these substances on the central nervous system was confounded with alcoholism which was associated with disability from neuropsychiatric disease in 12 of 20 painters and in only one of 10 electricians. Mortality and incidence of cancer were assessed among both cohorts and compared with the expected figures calculated from Geneva rates. Among painters there was a significant increase in overall mortality (O = 254, E = 218.5), in mortality from all cancers (O = 96, E = 75.4), and in incidence from all cancers (O = 159, E = 132.0). For the specific cancer sites, there was a significant excess risk for lung cancer (mortality: O = 40, E = 23.0), which was possibly related to occupational exposure to asbestos and to zinc chromate, although cigarette smoking was not controlled. The significant excesses of biliary tract cancer and of bladder cancer were in accordance with previous observations among painters from other countries. There was also a significant increase in incidence from testicular cancer (O=5, E=1.6), which has not been reported before. For causes of death other than cancer the excesses for alcoholism (O=5, E=0.8). for liver cirrhosis (O=14, E=8.8), for motor vehicle accidents (O=12, E=5.9), and for cerebrovascular disease when allowing for ten years of latency (O=8, E=4.0), were consistent with a probable increased risk of alcohol abuse. Among electricians overall mortality was similar to that expected (O=137, E=139.0). No significant excess risk was found for all cancers or for any specific cancer site. Because of the small number of expected deaths the statistical power was low for the assessment of a possible risk for leukaemia or for brain tumour.
Domestic asbestos exposure, lung fibre burden, and pleural mesothelioma in a housewife. M. Huncharek, J.V. Capotorto, J. Muscat. 1989;46(5):354-5. Case report PubMed · Publisher · Free full text

Summary

The authors reported a case of diffuse pleural mesothelioma in a housewife whose only documented asbestos exposure was domestic, and they presented measurements of asbestos fibres in her lung. The woman, a non-smoker born in 1906, developed right-sided chest pain in spring 1982. A right pleural effusion was found in November 1982. A pleural biopsy in January 1983 showed malignant mesothelioma of the biphasic subtype. The effusion was controlled with a chest tube and tetracycline, and she received no specific treatment for the tumour. She died in July 1983, aged 76. Necropsy showed mesothelioma of the right chest extending to the mediastinum, pericardium and left chest. She had no direct occupational exposure to asbestos. Her husband had worked for 34 years (1935-69) as a shipyard machinist dismantling boilers and other machinery. He said his work clothes became "covered with dust", and she regularly laundered them at home. Fibre analysis of her left lung found, per gram of dry lung tissue, 2.5 million chrysotile fibres, 0.8 million amosite and crocidolite fibres, and 3.2 million tremolite, actinolite and anthophyllite fibres. The authors concluded that household contact can produce lung fibre burdens similar to those seen in occupationally exposed people. They stated that such exposure should not be assumed to be "light" and may carry a significant risk of mesothelioma.

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Effect of retinoic acid on asbestos induced plasminogen activator activity of peritoneal macrophages. D. Lison, B. Knoops, R. Lauwerys. 1989;46(7):496-7. PubMed · Publisher · Free full text

Summary

The authors investigated whether retinoic acid, known to inhibit tumour-promoting effects of the phorbol ester PMA, also modulates induction of plasminogen activator (PA) activity by asbestos in macrophages. Peritoneal macrophages were obtained from mice injected with casein three days earlier and cultured. On the second day of culture they were stimulated with chrysotile fibres (50 ug/ml) for two hours. Retinoic acid was added before (15 minutes), during or after chrysotile stimulation. Membrane-bound PA activity was measured by release of p-nitroaniline from a chromogenic substrate. Results were the mean of three experiments, compared by analysis of variance and Scheffe's test. PA activity was 4.40 in controls and 6.47 with chrysotile alone (nmole p-nitroaniline per cells per hour). It was 2.33 when retinoic acid was preincubated before chrysotile, 2.89 when it was added with chrysotile, and 6.25 when it was added after chrysotile. Retinoic acid alone reduced activity to about 70% of control. It did not affect purified enzyme and showed no cytotoxicity by LDH release. The authors concluded that a low concentration of retinoic acid inhibited basal and asbestos-induced PA turnover rapidly and irreversibly, without acting on preformed enzyme. They suggested this may partly explain the antipromoting effect of retinoids. They concluded that this justified further study of retinoids in asbestos-induced neoplasia and lung fibrosis.

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Excessive accumulation of asbestos fibre in the bronchoalveolar space may be a marker of individual susceptibility to developing asbestosis: experimental evidence. R. Bégin, P. Sébastien. 1989;46(12):853-5. PubMed · Free full text

Abstract

Earlier studies have shown that only 60% of sheep exposed to a given chrysotile exposure developed asbestosis. Analyses of lung lavage (BAL) fibre content early in the disease showed that, despite identical injected doses, the subset of sheep with interstitial lung disease had significantly more fibre retention. To determine if the fibre retention preceded or followed early disease, 15 were exposed at 10 day intervals to 100 mg chrysotile by intratracheal injection. Animals were studied at three month intervals by chest radiograph (CR) and BAL. At month 15, 10 sheep had definitely abnormal CR (group B) and five had normal CR (group A). Fibre analyses of BAL reproduced earlier finding of a higher level of fibre retention early in the disease, month 15: 92 +/- 2 f/microliter in group B v 35 +/- 19 in group A. Moreover, at month 3, when no disease was detectable, group B already had a significantly higher fibre retention level: 84 +/- 2 in group B v 52 +/- 3 in group A (p less than 0.05). These data clearly imply that high alveolar dust retention precedes the disease process and that alveolar dust clearance capacity may be a major determinant of asbestosis.
Incidence of cancer and mortality among employees in the asbestos cement industry in Denmark. E. Raffn, E. Lynge, K. Juel, et al. 1989;46(2):90-6. PubMed · Publisher · Free full text

Abstract

In a cohort study of the incidence of cancer and mortality among 7996 men and 584 women employed in the Danish asbestos cement industry between 1928 and 1984 over 99% were traced. Chrysotile asbestos was the only fibre type used until 1946, when amosite and (in 1952) crocidolite were also introduced. Chrysotile constituted 89%, amosite 10%, and crocidolite 1% of the asbestos used. During the first 25 years of manufacture the exposure levels were high, especially in areas where the asbestos was handled dry. Measurements from 1948 indicate that the fibre levels may have ranged from 100 to 1600 times over the present Danish threshold limit value of 0.5 fibre/ml. In 1973 more than 41% of personal samples were higher than 2 f/ml. About 76% of the workforce left the factory within five years of starting employment. A total of 1346 deaths and 612 cases of cancer were observed in the cohort between 1943 and 1984. Among employed men the overall mortality (O/E 1.18; 95% CI 1.12-1.25), cancer mortality (O/E 1.32; 95% CI 1.19-1.46), and overall incidence of cancer (O/E 1.22; 95% CI 1.12-1.32) were significantly increased compared with all Danish men. This was not so among employed women. For men, significant excess risks were found for cancer of the lung (O/E 1.80; 95% CI 1.54-2.10), pleura (O/E 5.46; 95% CI 2.62-10.05), mediastinum (O/E 5.00; 95% CI 1.01-14.61), stomach (O/E 1.43; 95% CI 1.03-1.93), and other male genital organs (O/E 3.03; 95% CI 1.11-6.60). The mortality was significantly increased for men for non-malignant pulmonary diseases (O/E 1.63; 95% CI 1.33-1.98). Among the group of asbestos cement workers with first employment 1928-40 an excess risk of laryngeal cancer was found (O/E 5.50;95% CI 1.77-12.82). A total of 12 cases of pleural and one of peritoneal mesotheliomas was observed when the original notification forms were reviewed for all patients with cancer in the cohort.
Inflammation generating potential of long and short fibre amosite asbestos samples. K. Donaldson, G.M. Brown, D.M. Brown, et al. 1989;46(4):271-6. PubMed · Publisher · Free full text

Abstract

Previous studies have shown that long thin asbestos fibres are more pathogenic in in vivo and more active in in vitro assays than short fibre samples. In the present study a long fibre amosite asbestos sample and a short fibre sample prepared from it were tested for ability to cause inflammation in the peritoneal cavity of the mouse; a UICC sample intermediate in fibre size and an inert compact dust, TiO2, were also tested. The ability of the dust samples to cause inflammation, as judged by macrophage and neutrophil recruitment, was ranked in the order long fibre greater than UICC greater than short fibre greater than TiO2. Ability of amosite samples to cause inflammation was therefore related to the proportion of long fibres. The enhanced ability of long fibres to cause inflammation and cause macrophage activation is probably a key factor in the ability of long fibres to cause pulmonary fibrosis and may also be important in fibre carcinogenesis.
Natural history of pleural thickening after exposure to crocidolite. N.H. de Klerk, W.O. Cookson, A.W. Musk, et al. 1989;46(7):461-7. PubMed · Publisher · Free full text

Abstract

Serial plain chest radiographs of 384 men who worked at the Wittenoom crocidolite mine and mill between 1943 and 1966 and who applied for pneumoconiosis compensation between 1948 and 1982 have been examined independently by two trained observers for pleural disease using the 1980 ILO-UICC classification of radiographs to record width and extent of pleural disease. Radiographs covering follow up periods of from two to 38 years were examined (median number of films per subject was nine). The degree of crocidolite exposure was estimated from employment records and a survey of airborne fibre concentrations performed in 1966. Agreement between the observers on the presence and degree of pleural disease in the final film for each subject was moderately close (Kendall's tau B = 0.62) and was least for subjects with thickening less than 5 mm in width. Diffuse pleural thickening extending for greater than 50% of the lateral chest wall was the most common type recorded by both observers. Minor pleural thickening frequently progressed in extent along the lateral chest wall but progression beyond 5 mm in thickness was less common. Pleural plaques were not seen to progress beyond their initial thickness or extent. The rate of onset of thickening in this population increased continually from the time of first exposure and also increased slightly with age. There was evidence that the level of total cumulative exposure to crocidolite increased the rate of onset of pleural thickening in the period between five and 15 years after first exposure. Rate of progression of established thickening was greatest in subjects who first developed thickening early after first exposure. The relative rate of progression decreased slowly with time from first signs of thickening and there was no evidence of any progression more than 15 years after onset.
Pleural mesothelioma in a brake mechanic. M. Huncharek, J. Muscat, J.V. Capotorto. 1989;46(1):69-71. Case report PubMed · Publisher · Free full text

Summary

The authors described a case of pleural mesothelioma in a car brake mechanic whose only known asbestos exposure (chrysotile) came from 11 years of clutch and brake repair work. A 47-year-old man who had never smoked was admitted to hospital in November 1983 with right-sided pleuritic chest pain, shortness of breath and weight loss. He had had recurrent pleural effusion since 1978. Imaging showed a nodular pleural mass encasing the right hemithorax, with rib destruction and mediastinal lymph node involvement. Excisional biopsy showed epithelial malignant mesothelioma. He began chemotherapy with cisplatin, adriamycin and cyclophosphamide but refused further treatment in March 1984. He was readmitted in May 1986 and died later that month. Necropsy, histochemical and immunocytochemical staining, and electron microscopy supported the diagnosis. From 1966 to 1975, at ages 30 to 41, he had worked as a brake mechanic in five service stations or car dealerships. He often used compressed air to blow out brake drums, which created dusty conditions. No asbestos exposure was known in his other jobs. The discussion reviewed earlier studies that found chrysotile in brake drum dust and measured fibre concentrations during brake repair. The authors concluded that the mesothelioma risk from chrysotile exposure during brake and clutch work was poorly defined. They stated that better estimates of exposure, fibre characteristics and chrysotile's causal role were needed.

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Pleural mesothelioma in a lift mechanic. M. Huncharek, J. Muscat, J. Capotorto. 1989;46(7):500-1. Case report PubMed · Publisher · Free full text

Summary

The authors described a case of pleural mesothelioma in a man who had worked for 30 years as a lift mechanic. To their knowledge, it was the first such report in this occupational group. The patient, a 56-year-old man with a 40 pack-year smoking history, was noted in February 1984 to have unequal pupils, later diagnosed as a right Horner's syndrome. A chest CT scan in May 1984 showed a right paracervical mass. Biopsies at thoracotomy showed desmoplastic malignant fibrous mesothelioma extending to the chest wall, diaphragm and pericardium. He received chemotherapy and radiotherapy. A head CT scan showed evidence of metastasis to the left frontal area, and he died in May 1985. Necropsy showed tumour infiltrating the ribs and thoracic vertebrae, metastases in the opposite lung, both adrenal glands and the liver, and fibrous plaques in the right pleura and pericardium. Necropsy restrictions meant the suspected brain metastasis could not be examined. Expert review classified the tumour as desmoplastic diffuse pleural mesothelioma, biphasic. An occupational questionnaire showed that his main asbestos exposure was to lift brake linings, which he routinely cut, fitted and removed. The authors considered it conceivable that he was also exposed to asbestos building insulation. Citing reports of mesothelioma in vehicle brake repair workers, they concluded that a similar high risk among lift brake mechanics appeared plausible and that increased surveillance of this group may be justified.

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Pleural mesothelioma in a lift mechanic. D.J. Kilpatrick. 1989;46(12):894. Comment · Letter PubMed · Publisher · Free full text
Progression of asbestos effects: a prospective longitudinal study of chest radiographs and lung function. R.N. Jones, J.E. Diem, J.M. Hughes, et al. 1989;46(2):97-105. PubMed · Publisher · Free full text

Abstract

From an original prospective cohort of 244 current and ex-workers in two asbestos cement plants, longitudinal radiographic data covering ten years were available for 165 and lung function data covering about six years for 150. Estimates of average and cumulative dust exposure were available for each participant, all men. Radiographic progression (onset or worsening) was assessed by comparing earliest and latest films side by side. Annual changes in lung function were computed by fitting regression lines to all the data points. Small opacities (ILO category 1/0 or higher) were found in 16% of initial films, and progression of small opacities occurred in 13% of film pairs. Average and cumulative dust exposure were each significant determinants of the initial presence of small opacities, and were determinants of the progression of both parenchymal and pleural abnormalities. There was greater likelihood of progression if an abnormality was initially present, and a greater likelihood of progression in the plant that had systematic use of some crocidolite. Initial levels of lung function were related to smoking, exposure to dust, and initial radiographic status. Mean annual declines in lung function were modest (FVC-0.017 l/y, FEV1-0.020 l/y) and were related to smoking but not exposure to dust, initial radiographic status, or radiographic progression. Both plants used mainly chrysotile asbestos and exposure levels declined severalfold after 1960. Our findings suggest a waning effect of the larger remote dust exposures on recent annual change in lung function. This accords with human and experimental pathology data showing the relatively low resistance of chrysotile fibres to chemical alteration and clearance.
Progression of irregular opacities in asbestos miners. G.K. Sluis-Cremer, E. Hnizdo. 1989;46(12):846-52. PubMed · Publisher · Free full text

Abstract

All white and mixed race men who were employed in South African asbestos mines and mills between 30 November 1970 and 30 November 1975 were studied. The men who had two radiographs available, the first taken some time between the above two dates and the latest available radiograph which had to be at least two years after the first one numbered 1454: 793 continued exposure after the first radiograph and 661 did not. The films were read by a panel of three readers. Data available included age, years of exposure to asbestos and other mining, intensity of exposure to asbestos and other dust, and smoking habit. Progression was expressed as the difference between the average readings of radiograph 2--radiograph 1 in minor categories per year of irregular opacities. Changes in pleural abnormality were also measured. No differences of progression in the profusion or change in size of the irregular opacities were found between the two groups or in the number of zones affected. "New attacks" appeared equally frequently between the two groups. No difference in the change in extent of any type of pleural change was seen. It appears that once a dose of asbestos sufficient to initiate the disease has been retained it is inexorably progressive.
Pulmonary fibrosis in asbestos insulation workers with lung cancer. W. Weiss. 1989;46(6):430. Comment · Letter PubMed · Publisher · Free full text
Relation between asbestosis and bronchial cancer in amphibole asbestos miners. G.K. Sluis-Cremer, B.N. Bezuidenhout. 1989;46(8):537-40. PubMed · Publisher · Free full text

Abstract

In a necropsy series of 339 amphibole asbestos miners heavy smoking, age, and the presence of asbestosis were significantly associated with the presence of bronchial cancer. Of the 35 cases of bronchial cancer, 24 were associated with asbestosis. Eleven cases of bronchial cancer occurred in men without asbestosis; all were smokers. Standardised proportional mortality rates indicated no excess of bronchial cancer in 302 exposed men without asbestosis whereas these rates were progressively raised in men with slight or moderate/severe asbestosis. Of the four exposure variables introduced separately into a logistic regression model, "years of exposure" made a small but significant contribution; "residence time" marginally failed to achieve a 5% level of significance. Two other exposure variables tested including cumulative fibre exposure (fibre years) made no significant contribution. In the absence of asbestosis at necropsy a bronchial cancer in a man exposed to asbestos is unlikely to be due to asbestos.
Respiratory cancer in chrysotile textile and mining industries: exposure inferences from lung analysis. P. Sebastien, J.C. McDonald, A.D. McDonald, et al. 1989;46(3):180-7. PubMed · Publisher · Free full text

Abstract

In an attempt to explain the much greater risk of respiratory cancer at the same cumulative exposure in asbestos textile workers in Charleston, South Carolina, than in Quebec miners and millers, both exposed to chrysotile from the same source, 161 lung tissue samples taken at necropsy from dead cohort members were analysed by transmission electron microscopy. Altogether 1828 chrysotile and 3270 tremolite fibres were identified; in both cohorts tremolite predominated and fibre dimensions were closely similar. Lung fibre concentrations were analysed statistically (a) in 32 paired subjects matched for duration of employment and time from last employment to death and (b) in 136 subjects stratified by the same time variables. Both analyses indicated that the Quebec/Charleston ratios for chrysotile fibre concentration in lung tissue were even higher than the corresponding ratios of estimated exposure intensity (mpcf). After allowance for the fact that regression analyses suggested that the proportion of tremolite in dust was probably 2.5 times higher in Thetford Mines, Quebec, than in Charleston, the results from both matched pair and stratification analyses of tremolite fibre concentrations in lung were almost the same as for chrysotile. It is concluded that neither fibre dimensional differences nor errors in estimation of exposure can explain the higher risks of lung cancer observed in asbestos textile workers. The possible co-carcinogenic role of mineral oil used in the past in asbestos textile plants to control dust provides an alternative hypothesis deserving consideration.
Role of computed tomography in evaluating asbestos related lung disease. S. Lozewicz, R.H. Reznek, M. Herdman, et al. 1989;46(11):777-81. PubMed · Publisher · Free full text

Abstract

To find how computed tomography (CT) may be effectively used in individuals with suspected asbestos related lung disease 30 men with a history of exposure to asbestos were studied. All subjects underwent high kilovoltage posteroanterior and left lateral chest radiographs and chest CT. Eighteen were randomly selected asbestos workers referred for routine surveillance. The remaining 12 were patients who had been referred for investigation of respiratory symptoms or abnormal routine chest radiograph, or both, and found to have chest radiographic changes compatible with asbestos related lung disease. In the group referred for routine surveillance both pleural shadowing and pulmonary shadowing were shown on CT but not chest radiographs in only one case. Five were thought to have pleural shadowing on chest radiographs but this was confirmed on CT in only one case. All 12 patients referred for investigation showed pleural shadowing on chest radiographs; this was confirmed in all cases on CT which also showed unsuspected pulmonary shadowing in five cases. These findings suggest that it is not appropriate to use chest CT routinely in all asbestos workers referred for routine surveillance. When CT is used selectively in those with pleural shadowing on plain chest radiography, however, it is helpful in refuting or confirming the presence of pleural disease and may show unsuspected pulmonary shadowing.
Adsorption of benzo(a)pyrene on to asbestos and manmade mineral fibres in an aqueous solution and in a biological model solution. P. Gerde, P. Scholander. 1988;45(10):682-8. PubMed · Publisher · Free full text

Abstract

The adsorption of benzo(a)pyrene (BaP) on to three types of asbestos (chrysotile antophyllite, and amosite) and three types of manmade mineral fibres (MMMF) (rock wool, slag wool, and glass wool) in a physiological water solution was studied. Adsorption was determined from the decrease in the liquid concentration of BaP on the addition of the solid material. Results show that all the fibres weakly adsorb BaP, approximately within the same order of magnitude. The combined adsorption of BaP and phosphatidylcholine (PC) on to chrysotile and amosite asbestos and on to rock wool in aqueous solution was also studied. PC, one of the major constituents in lung surfactant, forms a separate lipid phase in water consisting of micellar liposomes or lipid bilayers. A decrease in the liquid concentration of PC was found when any of the three materials was added, indicating adsorption of the lipid phase on to the fibres. A coincident decrease in the liquid concentration of BaP was also found indicating that BaP is readily solubilised in PC and will accompany the adsorption of this compound on to the fibres. Owing to the high lipid aqueous partition coefficient of BaP, it is concluded that the direct adsorption of BaP on to the fibres will be negligible when PC is present in the system even at low concentrations. Phospholipid adsorption by the fibres and not their direct adsorption of aromatic hydrocarbons should therefore be the crucial parameter for this indirect interaction between fibres and aromatic hydrocarbons.
An epidemiological study in an Anatolian village environmentally exposed to tremolite asbestos. Y.I. Baris, N. Bilir, M. Artvinli, et al. 1988;45(12):838-40. PubMed · Publisher · Free full text

Summary

After four cases of malignant pleural mesothelioma were detected in the small village of Caparkayi, in the Sabanozu area of the Cankiri district of Turkey, about 90 km from Ankara, the authors carried out an epidemiological study there. The village had no asbestos mine nearby, and its main activities were farming and livestock breeding. Of the 425 inhabitants, 215 were aged 20 or over. All those over 20 completed a questionnaire on medical history, smoking, occupational asbestos exposure and respiratory symptoms, and four physicians examined them. Chest x-ray films were taken from 167 adults and evaluated by three chest specialists. Samples of the white stucco that all villagers had used for many years to paint their houses inside and out were analysed at McGill University. Mortality data for 1980 to 1987 came from health centre records. Of the 167 films, 63 (37.7%) showed abnormalities: interlobar fissure thickening 16.8%, diffuse interstitial fibrosis 15.6%, calcified pleural plaques 14.4%, pleural thickening 7.8%, and changes compatible with tuberculosis 4.2%. The stucco was rich in tremolite asbestos, including some very fine fibres. Adult deaths in 1980 to 1987 included two from mesothelioma, one from gastric carcinoma and one from lymphoma. The authors concluded that tremolite fibres were the real cause of the high incidence of mesothelioma and of some of the pleural and parenchymal changes in the village.

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Asbestos associated tumours in car mechanics. B. Järvholm, J. Brisman. 1988;45(9):645-6. PubMed · Publisher · Free full text
Asbestos related lung disease in maintenance workers. M. Huncharek, J. Capotorto. 1988;45(3):203-4. Letter PubMed · Publisher · Free full text
Correlation between fibre content of the lung and disease in east London asbestos factory workers. J.C. Wagner, M.L. Newhouse, B. Corrin, et al. 1988;45(5):305-8. PubMed · Publisher · Free full text

Abstract

The lungs from 36 past workers at an east London asbestos factory who had died from asbestos related disease were compared with lung tissue from 56 matched control patients being operated on in east London for carcinoma of the lung, correlating the severity of asbestosis and the presence of pulmonary carcinoma or mesothelioma of the pleura or peritoneum with an asbestos exposure index and type and amount of mineral fibre in the lungs. Asbestosis was associated with far heavier fibre burdens than mesothelioma. There was also a striking difference in the degree of asbestosis between the subjects with mesothelioma and those with carcinoma of the lung, the asbestosis being more severe in the latter. A further finding was that crocidolite and amosite were strongly associated with asbestosis, carcinoma of the lung complicating asbestosis, and mesothelioma, whereas no such correlation was evident with chrysotile or mullite. It is suggested that more emphasis should be placed on the biological differences between amphibole and serpentine asbestos fibre.
Effects of electrostatic charge on the pathogenicity of chrysotile asbestos. J.M. Davis, R.E. Bolton, A.N. Douglas, et al. 1988;45(5):292-9. PubMed · Publisher · Free full text

Abstract

Two groups of 48 rats of the AF/HAN strain were exposed for one year to respirable dust clouds of UICC chrysotile asbestos at a dose level of 10 mg/m3. One group was treated with dust carrying the normal electrostatic charge produced during dust generation, whereas the other was exposed to dust discharged by exposure to ionising radiation from a thallium-204 source. After dusting most animals were retained for their full life span. At the end of the dusting period those animals treated with normally charged dust had significantly more chrysotile retained in their lungs than animals exposed to discharged dust. Subsequently, animals treated with normally charged dust developed more pulmonary fibrosis and more pulmonary tumours. These findings suggest that the charge carried by airborne fibres should be taken into account when considering the health risks from exposure to chrysotile. Highly charged fibres are more likely to be deposited in lung tissue and thus constitute a greater hazard.
Exposure to asbestos and the risk of gastrointestinal cancer. 1988;45(8):573-6. Letter PubMed · Publisher · Free full text
Exposure to asbestos and the risk of gastrointestinal cancer: a reassessment. D.A. Edelman. 1988;45(2):75-82. PubMed · Publisher · Free full text

Abstract

In 1964 it was first reported that asbestos workers had a higher risk of gastrointestinal cancer. This notion has persisted despite several studies that have found no increased risk. The risks of gastrointestinal cancer to workers exposed to asbestos were reassessed, based on the results of published studies on 32 independent cohorts of asbestos workers. Not all studies provided risk estimates (SMRs) for all gastrointestinal sites (ICD codes 150-159). No consistent evidence was found to indicate that exposure to asbestos increases the risk of gastrointestinal cancer. Generally, the higher SMRs came from studies conducted in the United States or Canada and might reflect factors not related to exposure to asbestos. In studies in which asbestos exposed and non-asbestos exposed workers were evaluated the SMRs were not consistently higher for the group exposed to asbestos. There was no apparent dose response relation between accumulated asbestos dose and the risk of gastrointestinal cancer. It is concluded that there is no dose response relation between exposure to asbestos and risk of gastrointestinal cancer, and asbestos workers are not at an increased risk of gastrointestinal cancer.
Formation of 8-hydroxydeoxyguanosine by asbestos and man made mineral fibres. P. Leanderson, P. Söderkvist, C. Tagesson, et al. 1988;45(5):309-11. PubMed · Publisher · Free full text

Abstract

Samples of rockwool and glass fibre were compared with chrysotile fibres for their capacity to hydroxylate 2-deoxyguanosine to 8-hydroxydeoxyguanosine, a reaction that is mediated by formation of hydroxyl radicals. All three fibres produced 8-hydroxydeoxyguanosine in the absence of H2O2. The chrysotile fibres were most potent and produced about ten times more of the modified nucleoside than rockwool and glass fibre. This investigation shows that not only asbestos but also man made mineral fibres are able to modify nucleosides.
Health of vermiculite miners exposed to trace amounts of fibrous tremolite. J.C. McDonald, A.D. McDonald, P. Sébastien, et al. 1988;45(9):630-4. PubMed · Publisher · Free full text

Abstract

A small cohort of 194 men with low exposure to fibrous tremolite (mean 0.75 f/ml y) in the mining and milling of vermiculite in South Carolina experienced 51 deaths 15 years or more from first employment. The SMR (all causes) was 1.17 reflecting excess deaths from circulatory disease. There were four deaths from lung cancer and 3.31 expected (SMR 1.21, 95% CI 0.33-3.09). Three of the four deaths were in the lowest exposure category (less than 1 f/ml y); no death was attributed to mesothelioma or pneumoconiosis. These findings contrast with those in Montana where the vermiculite ore was heavily contaminated with fibrous tremolite. A radiographic survey of 86 current and recent South Carolina employees found four with small parenchymal opacities (greater than or equal to 1/0) and seven with pleural thickening. These proportions were not higher than in a non-exposed group and much lower than had been observed in Montana. Examination of sputum from 76 current employees showed that only two specimens contained typical ferruginous bodies, confirming low cumulative fibre exposure. Any possible adverse effects of work with vermiculite, minimally contaminated with fibrous or non-fibrous tremolite, were thus beyond the limits of detection in this workforce.
Immune response in shipyard workers with x ray abnormalities consistent with asbestos exposure. H. Anton-Culver, B.D. Culver, T. Kurosaki. 1988;45(7):464-8. PubMed · Publisher · Free full text

Abstract

The association of cellular and humoral immune responses with asbestos exposure was studied in two groups of 150 workers each from a shipyard population and compared with a population of Red Cross blood donors. One of the shipyard groups had both chest x ray evidence of asbestos exposure and work assignments that necessitated direct handling of asbestos. The other shipyard group had normal chest x ray films and no job assignments involving the direct handling of asbestos. Cellular immune responses studied were mitogen activation and measures of T helper and T suppressor cells. Humoral immune measures were IgG, IgA, and IgM. In shipyard workers with asbestos related x ray abnormalities there was a significant increase in pokeweed mitogen stimulation. In both shipyard groups compared with Red Cross blood donors were found (1) significantly higher IgG and IgA levels and (2) greater numbers of T helper and T suppressor cells; because of the disproportionately large number of T suppressor cells, Th/Ts ratios were lower than in the Red Cross controls. Observations of differences in humoral and cellular immune response may point the way to the early diagnosis of the clinical manifestation of asbestos related disease.
Incidence of cancer among welders, platers, machinists, and pipe fitters in shipyards and machine shops. S. Tola, P.L. Kalliomäki, E. Pukkala, et al. 1988;45(4):209-18. PubMed · Publisher · Free full text

Abstract

The incidence of cancer in 12,693 shipyard and machine shop male workers (1689 welders, 4308 platers, 6003 machinists, 693 pipe fitters) employed for at least one year between 1945 and 1960 was investigated in a retrospective cohort study. The welders had welded only mild steel and had not been exposed to hexavalent chromium containing fume. The follow up was 99.7% complete and the total number of person-years was 304,682. The incidence of cancer in 1953-81 was ascertained through the Finnish Cancer Registry. The observed numbers of cases of cancer were compared with the expected numbers based on regional urban rates. The smoking habits of the cohort were surveyed with a postal questionnaire sent to a sample of 961 workers. The smoking habits of the cohorts were similar and smoking was not more common than among the general population. The total number of cases of cancer was 611 (exp 629) among the shipyard workers and 376 (exp 388) among the machine shop workers. The incidence of lung cancer was increased among the shipyard workers (obs 227, exp 192). This excess was observed in all the worker groups and was most evident for the pipe fitters and platers. Among the machine shop workers, the incidence of lung cancer was lower than expected with the exception of the welders who had a slightly raised risk of lung cancer (obs 14, exp 10). The incidence of laryngeal cancer was slightly raised among the shipyard workers (obs 24, exp 20) but not in the machine shop workers. No excess risk was observed among the welders. The incidence of cancer of the prostate was increased among the machine shop workers (obs 39, exp 31) but not in the shipyard workers. The excess was statistically significant for the welders. No pronounced excess could be found for other types of cancer. Analysis by the duration or exposure showed that the excess of lung cancer in the shipyard workers was most evident during the last period of observation (1972-81). No other trends were obvious and the slight excess of lung cancer observed among the welders did not increase with increasing follow up time. No excess risk for mesothelioma was found. The small excess of lung cancer in welders could be due to chance. The fact that only a small and statistically insignificant excess of lung cancer could be found among this group of heavily exposed welders suggest that if the risk of lung cancer was associated with welding this risk must nowadays be low and probably too low to be unequivocally detected in most epidemiological studies.
International classification trial of AIA set of 100 radiographs of asbestos workers. C.E. Rossiter, K. Browne, J.C. Gilson. 1988;45(8):538-43. PubMed · Publisher · Free full text

Abstract

A series of 100 full size radiographs illustrating the range of asbestos related radiographic changes was collected by the Asbestos International Association to provide a demonstration and teaching supplement to the ILO 1980 International Classification of the Radiographic Appearances of Pneumoconioses. Each film was read by 12 experienced readers from ten countries; the readings have been summarised by a median reading, with the range covered by two thirds of the readers. The occupational histories and some relevant clinical information are also available. It is proposed that, in the use of this set, readers should classify each film using the ILO classification rules, particularly without reference to the summary reading or the additional information. Comparing the individual readings by the 12 readers, most of the variation in reading the profusion of small opacities was ascribable only to random variation, with little consistent bias between readers. By contrast, two readers recorded pleural changes much more frequently than their colleagues. This illustrated a major problem with the ILO 1980 Classification. Several others which occurred in this reading trial are also discussed.
Lobe of origin in the attribution of lung cancer to asbestos. W. Weiss. 1988;45(8):544-7. PubMed · Publisher · Free full text

Abstract

Lung cancer originates most commonly in the upper lobes in the general population but among workers with asbestosis it is most common in the lower lobes. Published data on lobar distribution were used to estimate the probabilities that lung cancer among asbestos workers is attributable to exposure to asbestos. This attribution varies directly with the relative risk. Critical values of the relative risk at which attribution of lung cancer to asbestos equalled its attribution to other causes, mainly smoking, were calculated. At a relative risk above 2.81 upper lobe cancers were more likely to be due to asbestos than not. For middle and lower lobe cancers, the critical relative risk was 1.55. These critical values were compared with published standardised mortality ratios reported for cohorts of workers with asbestosis. Since the ratios ranged from 6.3 to 9.1, the probability that lung cancer in such cases is due to asbestos is high regardless of lobe of origin. In many cohorts unstratified by the presence or absence of asbestosis the risk ratios are below one or both of these critical values. Since risk ratios are so high among workers with asbestosis, the ratios must be lower for workers without asbestosis than the overall ratios for unstratified cohorts. Therefore, the critical values may be useful in workers without asbestosis among such cohorts to estimate the upper limit of the probability that lung cancer in a given lobe is due to exposure to asbestos.
Low level exposure to asbestos: is there a cancer risk?. J.M. Davis, J.C. McDonald. 1988;45(8):505-8. Review PubMed · Publisher · Free full text

Summary

This editorial asked whether low occupational and environmental exposures to asbestos carry a cancer risk, and whether there is a safe threshold below which asbestos does not cause tumours. The authors reviewed experimental and epidemiological evidence. In rats, exposure for one day gave results similar to those in unexposed controls. In injection studies with doses from 25 mg down to 0.01 mg, the time to tumour lengthened as dose fell. The most dangerous fibres were longer than 8 µm and thinner than 0.25 µm. A short-fibre amosite preparation produced neither fibrosis nor tumours, and chrysotile was cleared from lung tissue much faster than amosite. The authors stated that epidemiological studies become increasingly unreliable as exposure falls. For example, no significant rise in lung cancer would have been detected among nearly 2000 chrysotile mine and mill workers employed at least 20 years at about 20 fibres/cc. They suggested that mesothelioma in people reputedly exposed only to chrysotile may largely result from tremolite contamination. Female mesothelioma mortality showed no apparent increase in a combined population of some 300 million, from which they concluded that the risk from non-occupational exposure must be extremely small. They concluded that zero risk at very low exposure may be impossible to prove or disprove. Any lung cancer increase below current control limits would not be detected. Priorities for reducing such risks were for society, not science, to decide.

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Malignant mesothelioma in a cohort of asbestos insulation workers: clinical presentation, diagnosis, and causes of death. J. Ribak, R. Lilis, Y. Suzuki, et al. 1988;45(3):182-7. PubMed · Publisher · Free full text

Abstract

Malignant mesothelioma has been rare in the general population. In recent decades its incidence has risen dramatically, parallel to the increasing use of asbestos in industry since 1930. Altogether 17,800 asbestos insulation workers, members of the International Association of Heat and Frost Insulators and Asbestos Workers (AFL-CIO-CLC) in the United States and Canada, were enrolled for prospective study on 1 January 1967 and followed up to the present. Every death that occurs is investigated by our laboratory. One hundred and seventy five deaths from mesothelioma occurred among the 2221 men who died in 1967-76 and 181 more such deaths in the next eight years. Altogether, 356 workers had died of malignant mesothelioma (pleural or peritoneal) by 1984. Diagnosis of mesothelioma was accepted only after all available clinical, radiological, and pathological material was reviewed by our laboratory and histopathological confirmation by the pathology unit made in each case. One hundred and thirty four workers died of pleural and 222 of peritoneal mesothelioma. Age at onset of exposure, age at onset of the disease, and age at death were similar in both groups of patients. Significant difference was noted only in the time elapsed from onset of exposure to the development of first symptoms, which was longer in the group with peritoneal mesothelioma. Shortness of breath, either new or recently increased, and chest pain were the most frequent presenting symptoms in the group with pleural mesothelioma; abdominal pain and distension were frequent in the patients with peritoneal mesothelioma. Pleural effusion or ascites were found in most patients. The most effective approach to the diagnosis of malignant pleural mesothelioma in these cases was by open lung biopsy; exploratory laparotomy was best for diagnosing peritoneal mesothelioma. Patients with pleural mesothelioma died principally from pulmonary insufficiency whereas those with peritoneal mesothelioma succumbed after a period of pronounced wasting.
Malignant pleural mesothelioma in a nuclear engineer. M. Huncharek, K. Smith, R. Milatou. 1988;45(7):498-9. Case report PubMed · Publisher · Free full text

Summary

The authors described a case of malignant pleural mesothelioma in a nuclear engineer. They reported it as, to their knowledge, the first case in this occupational group after work-related asbestos exposure. A previously healthy 49 year old man was admitted to hospital in February 1979 with right chest pain and pleural fluid. A second thoracentesis in July 1979 was positive for malignancy, and fluoroscopy showed parietal pleural plaques of 1-3 mm. After pleural biopsy, he underwent right pleural pneumonectomy in October 1979. Cytological and histological features were consistent with malignant pleural mesothelioma. He received radiotherapy and chemotherapy. In December 1980 he developed pericarditis, and pericardial biopsy was positive for mesothelioma. He died in late January 1981. Necropsy showed epithelial mesothelioma in the mediastinum, diaphragm and pericardium, with invasion into the myocardium. He had worked for 27 years as a research nuclear engineer designing sodium cooled atomic power stations and had reported no asbestos exposure. Questioning of coworkers established that the reactors were insulated with asbestos. Sawing of the insulation created heavy dust while engineers, including the patient, were present. A coworker who built the reactor test equipment for five years also died of pleural mesothelioma. The authors concluded that the patient was exposed intermittently and secondarily to asbestos at work. They stated that nuclear engineering personnel may be at substantially increased risk of mesothelioma through such "bystander" exposure.

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Mortality and incidence of cancer among oil exposed workers in a Norwegian cable manufacturing company. Part I. Exposure conditions 1920-79. A. Rønneberg, K. Skyberg. 1988;45(9):589-94. PubMed · Publisher · Free full text

Abstract

Heavy high viscosity oils, transformer oils, and very light low viscosity oils have been used in a Norwegian company in the impregnation, sheathing, and installation of paper insulated cables. The aim of the present study was to determine exposures to oils and other chemicals at these workplaces from 1920 to 1979. Oil mist was sampled on glass fibre or membrane filters and analysed by infrared spectroscopy. Oil vapour concentrations were measured with a direct reading total hydrocarbon analyser with a flame ionisation detector. The results suggested average oil mist levels of 0.5-4 mg/m3 and oil vapour levels within 10-100 mg/m3. Definitive exposure to asbestos occurred in sheathing until the late 1950s, whereas only minor exposure to asbestos took place in installation and impregnation.
Mortality in miners and millers of crocidolite in Western Australia. B.K. Armstrong, N.H. de Klerk, A.W. Musk, et al. 1988;45(1):5-13. PubMed · Publisher · Free full text

Abstract

It is known that 6505 men and 411 women were employed in the mining and milling of crocidolite at Wittenoom in the Pilbara region of Western Australia between 1943 and 1966. Employment was usually brief (median duration four months) and exposure intense (median estimated cumulative exposure 6 fibres/cc years). The vital status of 73% of the men and 58% of the women employed in the industry was known at 31 December 1980, providing 95 264 person-years of follow up with 820 deaths in men and 4914 person-years with 23 deaths in women. The standardised mortality ratio (SMR) for all causes in men was 1.53 (95% confidence interval 1.43 to 1.64). Statistically significant excess death rates were observed in men for neoplasms, particularly malignant mesothelioma (32 deaths), neoplasms of the trachea, bronchus, and lung (SMR 2.64), and neoplasms of the stomach (SMR 1.90); respiratory diseases, particularly pneumoconiosis (SMR 25.5); infections, particularly tuberculosis (SMR 4.09); mental disorders particularly alcoholism (SMR 4.87); digestive diseases, particularly peptic ulceration (SMR 2.46) and cirrhosis of the liver (SMR 3.94); and injuries and poisonings, particularly non-transport accidents (SMR 2.36). The excess mortality from pneumoconiosis, malignant mesothelioma, and respiratory cancers, but not stomach neoplasms, was dependent on time since first exposure and cumulative exposure. There was no increase in mortality from laryngeal cancer (SMR 1.09) or neoplasms other than those listed. The SMR for all causes in women was 1.47 (95% confidence interval 0.98-2.21) and for neoplasms 1.99; there was one death from malignant pleural mesothelioma.
Mortality of workers at acetylene production plants. M.L. Newhouse, G. Matthews, K. Sheikh, et al. 1988;45(1):63-9. PubMed · Publisher · Free full text

Abstract

To reduce the risk of explosion oxyacetylene cylinders are filled with a spongy mass, acetone is added to saturate the mass, and acetylene is pumped into the cylinder. The first cylinders manufactured before 1936 used a kapok filling topped off with about 16 oz of crocidolite asbestos, with a metal gauze thimble inserted to reduce risk of flash back. Cylinders must be examined annually. The use of crocidolite ceased in 1972 and other fillings have been adopted since 1970; kapok cylinders now constitute less than 5% of the total stock. To assess possible hazards, a mortality study of workers first employed between 1935 and 1975 and followed up to December 1984 was undertaken. Simulation tests showed low concentrations of asbestos in the air even in the earliest period. The population studied consisted of 370 workers at the Bilston plant in the West Midlands, 611 at the 14 other plants in England and Wales, and 120 in Scotland. No deaths occurred from mesothelial tumours but there was an excess of deaths from cancer, particularly lung cancer, cancer of the stomach, and cancer of the pancreas, the latter accounting for eight deaths. Risks appeared to be concentrated at the Bilston plant. The importance of these findings is discussed.
Non-occupational asbestos related chest diseases in a small Anatolian village. Y.I. Bariş, M. Artvinli, A.A. Sahin, et al. 1988;45(12):841-2. Case report PubMed · Publisher · Free full text

Summary

The authors described chest and other diseases among people from a small village in Central Anatolia, Turkey, where non-occupational pleural asbestosis and mesothelioma had been reported in other villages. Between 1984 and 1987 they collected seven patients from Caparkayi village in the Cankiri district, which had a population of 425. The village had no asbestos mine, mill or factory. Its houses were made of mudbrick and rocks, with walls plastered with a white stucco. Four women aged 26, 30, 33 and 40 had malignant pleural mesothelioma, diagnosed by pleural punch biopsy or limited thoracotomy. All four were non-smoking housewives, and three had moved to Ankara at ages 19 to 21. Chest x ray films of the parents of two of these patients showed calcified pleural plaques or calcification compatible with asbestos exposure. A 58 year old woman had asbestosis. Mineralogical examination of her lung biopsy showed many fibres identified as tremolite. A 56 year old male farmer and heavy smoker had gastric carcinoma, and a 50 year old woman had Hodgkin's disease. None of the patients had been occupationally exposed to asbestos. The authors suggested that they may have inhaled tremolite from the stucco-plastered house walls, and that childhood exposure could explain the young age of the mesothelioma patients. They concluded that four mesotheliomas in a village of 425 was unusual and that tremolite was the likely cause.

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Projection of asbestos related diseases in the United States, 1985-2009. I. Cancer. D.E. Lilienfeld, J.S. Mandel, P. Coin, et al. 1988;45(5):283-91. PubMed · Publisher · Free full text

Abstract

Projections of asbestos associated cancer mortality in the United States during the 25 year period 1985-2009 were made based on previously published estimates. These estimates were reviewed for malignant mesothelioma, lung cancer, and gastrointestinal cancers. Particular attention was given to the assumptions used in the original derivation of the estimates. For malignant mesothelioma mortality, previous estimates ranged from 15,500 to 300,000. Using recently published data from the Surveillance, Epidemiology, and End Results project, coupled with the previously published estimates, projected asbestos related malignant mesothelioma mortality in the United States for the period 1985-2009 was estimated to be 21,500. For lung cancer, previous estimates were reviewed, particularly with regard to the ratio of deaths from lung cancer to deaths from malignant mesothelioma. Using these ratios, a range of projected deaths was established and a median of those estimates used as a project, which was 76,700 such deaths in the United States between 1985 and 2009. Gastrointestinal cancer mortality has been projected by only three investigators. A median of those estimates (33,000) was used. In conclusion it is estimated that 131,200 deaths from asbestos associated cancer will occur in the United States between 1985 and 2009.
Pulmonary clearance of UICC amosite fibres inhaled by rats during chronic exposure at low concentration. A.D. Jones, C.H. McMillan, A.M. Johnston, et al. 1988;45(5):300-4. PubMed · Publisher · Free full text

Abstract

Clearance of UICC amosite asbestos from the lungs during chronic--that is, repeated--exposure was investigated by using the scanning electron microscope to measure lung burdens from rats which had inhaled amosite asbestos at an approximately constant concentration of 0.1 mg/m3 or, equivalently, 20 fibres/ml for seven hours a day, five days a week for up to 18 months. The lung burdens were compared with previous results for higher exposure concentrations of 1 and 10 mg/m3. Those previous lung burdens had been measured using other analytical methods (infrared spectrophotometry) that were not suitable for the new lower lung burdens. Taken together, these results showed lung burdens rising pro rata with exposure concentration and exposure time. This accumulation of lung burden has been described by a kinetic model that takes account of the sequestration of material at locations in the lung from where it cannot be cleared. Unlike some earlier models in which lung burdens eventually reach a plateau with equilibrium between deposition and clearance during chronic exposure, this sequestration model shows lung burdens continuing to rise with exposure time. The latest results reported here support the application of such a model to lower exposure concentrations closer to those of asbestos in workplaces.
Respiratory health in chrysotile asbestos miners in British Columbia: a longitudinal study. D.A. Enarson, V. Embree, L. MacLean, et al. 1988;45(7):459-63. PubMed · Publisher · Free full text

Abstract

A respiratory survey was undertaken in chrysotile asbestos miners in British Columbia consisting of a questionnaire, spirometry, chest radiography, and physical examination. The tests were performed in 1977 and again in 1983. The population groups studied included 63 "exposed" (working in the plant more than nine years), 52 "controls" (working in the plant less than five years), and 38 residents of the village at the minesite. A subset of 39 was identified with high exposure (worked in the mill more than five years). Measured levels of environmental particulates were similar over the entire period of operation of the plant (1.4 to 14.0 million particles per cubic foot and 0.7-88.0 fibres/cc in the mill; 0.2 to 2.7 mpcf and 0.6 to 9.3 f/cc in the mine). The exposed groups were more likely to report cough and breathlessness than the two other groups and were also more likely to have abnormal FVC and chest x ray films (the latter not significant, p greater than 0.05) and to be more likely to have a combination of these abnormalities. There was no trend to progression in the combination of abnormalities associated with exposure on follow up. The heavily exposed group showed a significantly worse trend in FVC. This adverse trend was confined to those with initial abnormalities. Tobacco smoking did not increase the trend to progression in this group.
Risk assessment in the asbestos cement industry. M.M. Finkelstein. 1988;45(3):201-3. Letter PubMed · Publisher · Free full text
Risk assessment in the asbestos cement industry. K. Browne. 1988;45(10):720. Letter PubMed · Publisher · Free full text
Serum type III procollagen peptide in asbestos workers: an early indicator of pulmonary fibrosis. A. Cavalleri, F. Gobba, L. Bacchella, et al. 1988;45(12):818-23. PubMed · Publisher · Free full text

Abstract

Serum type III procollagen peptide (PIIIP) concentrations were determined in 36 male workers exposed to asbestos fibres in the production of asbestos cement items and in 13 healthy male controls. Mean (SD) PIIIP serum concentrations were 9.3 (1.5) ng/ml (range 7-12) in the controls and 13.7 (3.5)ng/ml (range 7.5-20) in the asbestos workers; the difference was statistically significant (p less than 0.01). The exposed workers were subdivided according to presence or absence of radiological signs of asbestosis and intensity and duration of exposure. PIIIP serum values of workers with asbestos related interstitial fibrosis were the highest of the groups at 14.6 (2.3) ng/ml. In workers with heavy exposure the PIIIP values were significantly related to duration of exposure (r = 0.95; p less than 0.01). PIIIP serum values may be a useful index for the early diagnosis of asbestos induced pulmonary fibrosis and its use should be considered as part of the biological monitoring of exposed workers.
Symptomatic benign pleural effusions among asbestos insulation workers: residual radiographic abnormalities. R. Lilis, Y. Lerman, I.J. Selikoff. 1988;45(7):443-9. PubMed · Publisher · Free full text

Abstract

During a cross sectional medical survey of 2815 insulation workers with 30 years or more from onset of asbestos exposure conducted from 1981 to 1983, a positive history of benign pleural effusion was found in 20 (0.71%). Two or three such episodes had occurred in four of these 20 subjects. The chest x ray abnormalities in these cases were characterised by pleural fibrosis in 19 and diffuse pleural fibrosis with blunting of the corresponding costophrenic angle in 16. In the total group of 2815 insulation workers diffuse pleural fibrosis was found in 142 (5.0%). Thus diffuse pleural fibrosis with blunting of the corresponding costophrenic angle is a frequent residual abnormality after benign pleural effusion. Its impact on pulmonary function can be pronounced.
Asbestos and cancer: a cohort followed up to death. P.E. Enterline, J. Hartley, V. Henderson. 1987;44(6):396-401. PubMed · Publisher · Free full text

Abstract

The mortality experience of 1074 white men who retired from a United States asbestos company during the period 1941-67 and who were exposed to asbestos working as production and maintenance employees for the company is reported to the end of 1980 when 88% of this cohort was known to be dead. As noted in earlier reports the mortality for respiratory and gastrointestinal cancer was raised. A more detailed examination of causes of death shows that the excess in gastrointestinal cancer was largely due to a statistically significant excess in stomach cancer. A statistically significant excess was also noted for kidney cancer, cancer of the eye, and non-malignant respiratory disease. Eight deaths from malignant mesothelioma were observed, two of which were peritoneal. Asbestos exposures for these mesothelioma cases were low relative to other members of the cohort. Continuing follow up of this cohort shows a dose response relation for respiratory cancer that has become increasingly linear. Standardised mortality ratios peaked 10 to 15 years after retirement and were relatively constant at around 250 in each five year interval starting in 1950. This excess might have been detected as early as 1960 but certainly by 1965. The mortality experience of this cohort reflects the ultimate effects of asbestos since nearly all of the cohort has now died.
Chrysotile asbestos exposure and mesothelioma. M. Huncharek. 1987;44(4):287-8. Letter PubMed · Publisher · Free full text

Summary

In this letter, the author responded to a paper by Gardner and colleagues (1986;43:726-32) on the continuing controversy over the carcinogenic potential of chrysotile asbestos. He noted that available data suggested amphibole fibres were more potent than chrysotile for producing mesothelioma, but that this relation was not well defined for lung cancer. He cited a reported statistically significant excess of lung cancer mortality among textile workers exposed exclusively to chrysotile. He suggested that chrysotile fibres physically altered by industrial processing or consumer use might be hazardous, and that brake repair workers, exposed solely to chrysotile, had not been systematically investigated. As part of an epidemiological study of diffuse pleural mesothelioma at the Canadian Tumor Reference Center, he had made a preliminary review of 37 necropsy-confirmed cases associated with occupational asbestos exposure. Three cases, all male, had the job titles brake mechanic (auto), elevator mechanic and railroad brake banding. They were aged 56 to 65, with exposure histories of one month, 30 years and 36 years. Two tumours were sarcomatous and one biphasic, and all three had distant metastases. Electron microscopy of three pleural specimens from the auto mechanic found 51 to 266 x 10^6 fibres per gram of wet tissue, 99% chrysotile and 1% amosite. The author noted that some investigators had considered asbestos exposure during brake repair to be low. He concluded that other occupational and non-occupational groups exposed to chrysotile should be investigated to define their mesothelioma risk more accurately.

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Determinants of respiratory symptoms in insulation workers exposed to asbestos and synthetic mineral fibres. P. Ernst, S. Shapiro, R.E. Dales, et al. 1987;44(2):90-5. PubMed · Publisher · Free full text

Abstract

The determinants of respiratory symptoms were studied in an active workforce of insulation workers exposed to asbestos and synthetic mineral fibres. Responses to a mailed respiratory symptom questionnaire from 537 insulation workers without diagnosed asbestosis were analysed using logistic regression. Wheezing complaints and breathlessness were related primarily to current cigarette smoking and to symptoms suggesting an asthmatic predisposition antedating work in the trade. There was also evidence that these complaints were related to occupational exposure (estimated by number of hours worked in the trade) in subjects with prior airways hyperreactivity. An asthmatic predisposition antedating work in the trade was the major determinant of acute respiratory symptoms in the workplace. The effects of workplace exposures on respiratory symptoms may have been underestimated due to selective withdrawal from the active workforce and due to inaccuracies in the measure of exposure used.
Development, radiological zone patterns, and importance of diffuse pleural thickening in relation to occupational exposure to asbestos. H. Bohlig, A. Calavrezos. 1987;44(10):673-81. PubMed · Publisher · Free full text

Abstract

The radiographic appearance of the lateral pleura was divided into an upper, a middle, and a lower zone. Bilateral changes of the pulmonary layer of the pleura (diffuse pleural thickening) within the upper pleural zones were found in 863 (71%) of 1204 workers exposed to asbestos and in 249 (40%) of 622 non-exposed controls. Downwards along the chest wall this ratio of 7:4 increased progressively up to 10:1 at the lower parts of the pleura. Bilateral diffuse pleural thickening in at least two adjacent zones on each side was found in 652 (54%) of exposed and in only 86 (14%) of unexposed subjects. The difference was even more striking when comparing bilateral involvement of all three zones (28% and 3% respectively). Unilateral change was rare (4.8% and 7.8% respectively) and often due to causes other than exposure to asbestos. Pleural findings were the earliest radiographic features detectable associated with former exposure to asbestos. Bilateral diffuse thickening in at least two adjacent zones on each side seems to be a striking feature and an early indication of former occupational asbestos damage. Modifications of the International Labour Organisation 1980 classification are proposed.
Enhanced lipid peroxidation and lysosomal enzyme activity in the lungs of rats with prolonged pulmonary deposition of crocidolite asbestos. J. Jajte, I. Lao, J.M. Wiśniewska-Knypl. 1987;44(3):180-6. PubMed · Publisher · Free full text

Abstract

The interaction of UICC crocidolite asbestos with biological membranes in vivo was studied in rats after a single intratracheal dose of a suspension of 20 mg of fibres per rat. Development of lung fibrosis (increased level of hydroxyproline, a collagen index together with corresponding pathomorphological alteration) confirmed the penetration of crocidolite fibres into the lungs in the course of seven months exposure. The pulmonary deposition of crocidolite affected the lysosomal membranes of lung cells as manifested by (1) enhanced lipid peroxidation with (2) stimulation (release) of activity of beta-glucuronidase and cathepsin D. Enhanced lipid peroxidation and activity of beta-glucuronidase may contribute to the delayed, carcinogenic effects of crocidolite asbestos.
Factor analysis of clinical data from asbestos workers: implications for diagnosis and screening. P. Harber, M. Lew, D.P. Tashkin, et al. 1987;44(11):780-4. PubMed · Publisher · Free full text

Abstract

Clinical data from 624 asbestos exposed workers were analysed by factor analysis. Fifteen clinical variables were found to reflect several underlying factors: "obstruction," "interstitial disorder," "x ray change," "air tapping," and "age/exposure." Scoring individual subjects along these axes can facilitate identifying early cases and avoiding false diagnosis. The analysis suggests that screening should be multimodal and that radiographic abnormality need not imply physiological impairment.
Ferruginous bodies and pulmonary fibrosis in dead low to moderately exposed asbestos cement workers: histological examination. L.G. Johansson, M.P. Albin, K.M. Jakobsson, et al. 1987;44(8):550-8. PubMed · Publisher · Free full text

Abstract

Histological slides from the lungs of 89 dead asbestos cement workers have been examined with respect to ferruginous bodies and fibrosis. The results have been compared with individually matched controls with no known exposure to asbestos, and related to asbestos exposure, expressed as duration of exposure and cumulative asbestos dose, and smoking habits. The asbestos cement workers studied had been employed for on average 15 years, with a mean cumulative dose of 26 fibre-years per ml (f-y/ml). Clear dose-response relations between exposure (duration of exposure and cumulative asbestos dose) and level of ferruginous bodies were found. An association was evident already at a low cumulative dose (1-10 f-y/ml). Fibrosis was more common and more pronounced among the exposed workers than among controls. An association between ferruginous bodies and fibrosis was also found. Among the controls, but not among exposed workers, there was an association between smoking history and fibrosis.
Malignant mesothelioma in Singapore. S.F. Ho, H.P. Lee, W.H. Phoon. 1987;44(11):788-9. PubMed · Publisher · Free full text
Mortality of workers employed in two asbestos cement manufacturing plants. J.M. Hughes, H. Weill, Y.Y. Hammad. 1987;44(3):161-74. PubMed · Publisher · Free full text

Abstract

In a study of the mortality experience of 6931 employees of two New Orleans asbestos cement products manufacturing plants over 95% were traced. Chrysotile was the primary fibre used in both plants. Plant 1 also used small amounts of amosite and, later, crocidolite irregularly whereas plant 2 used crocidolite steadily in pipe production. Previously reported exposure concentration estimates were revised, based on additional air sampling data and re-evaluation of these data. Workers in the two plants had similar duration of employment (overall, a mean of 3.8 years) and estimated exposure concentration (a mean of 7.6 million particles per cubic foot (mppcf)). Mortality was similar for these plants and comparable with Louisiana rates for all causes combined, nonmalignant causes, and primary cancers of specified sites other than lung. Short term workers from both plants showed raised and similar risk of lung cancer, but risk among longer term workers differed--for example, for workers employed over one year there was no excess in plant 1 (16 observed, 17.2 expected) but a significant excess in plant 2 (52 observed, 28.9 expected, p less than 0.001). After excluding short term workers, risk of lung cancer in plant 2 showed a significant trend with estimated cumulative asbestos exposure; using a conversion of 1.4 fibres/ml = 1 mppcf, the slope of the line was 0.0076. The slope for plant 1 was 0.0003. Among all workers (the 6931, plus 167 early employees) ten mesotheliomas had occurred up to 1984: two from plant 1, eight from plant 2. In plant 2 a case-control analysis found a relation between risk of mesothelioma and duration of employment (p less than 0.01) and proportion of time spent in the pipe area (p less than 0.01), thus adding to the evidence of a greater risk of mesothelioma from crocidolite than chrysotile asbestos. A review of the mortality findings of eight cohorts of asbestos cement workers is presented.
Non-malignant asbestos diseases in workers in an electrochemical plant. B. Hilt. 1987;44(9):621-6. PubMed · Publisher · Free full text

Abstract

The prevalence of non-malignant asbestos related disorders was studied in a group of men who had been subjected to different levels of asbestos exposure when working at an electrochemical plant producing nitric acid sometime between 1928 and 1970. There were 153 men eligible for an initial clinical examination in 1979-80 and that group has been followed up to 1985. Among the cohort members the "accumulated prevalence" of lung fibrosis alone or in combination with pleural plaques and of "pleural plaques only" was 24.2% and 24.8% respectively. The subgroup with the heaviest exposure had a total prevalence of asbestos related disorders of 82.5%. Only study subjects with lung fibrosis had statistically significant increased prevalences of respiratory symptoms. All subgroups from the study population, however, had mean spirometric values under the age, height, and smoking specific predicted means. Subjects with heavy asbestos exposure and current smoking had a prevalence of three or more respiratory symptoms of 28.8% compared with 5.6% among lightly exposed never smokers. Pleural crepitations at chest auscultation were more prevalent among subjects with radiologically visible asbestos related disorders than among study subjects with normal chest x ray films. During the follow up from 1980 to 1985, three cases of lung cancer, two of pleural malignant mesothelioma, and one of stomach cancer were found among the cohort members.
Non-malignant chest x ray changes in patients with mesothelioma in a large cohort of asbestos insulation workers. R. Lilis, J. Ribak, Y. Suzuki, et al. 1987;44(6):402-6. PubMed · Publisher · Free full text

Abstract

To assess the prevalence of non-malignant chest x ray abnormalities in cases of mesothelioma 184 cases of mesothelioma (72 pleural and 112 peritoneal) which had occurred in a cohort of asbestos insulation workers followed up since 1967 were studied. Chest x ray films of satisfactory quality, on which the presence or absence of non-malignant radiological changes indicating interstitial pulmonary fibrosis or pleural fibrosis or both, could be assessed with a high degree of certainty were available. In some cases (20% for pleural mesothelioma, 11.6% for peritoneal mesothelioma) non-malignant radiological changes were not radiologically detectable. Parenchymal interstitial fibrosis (small irregular opacities) only was found in a proportion of cases (25.4% of pleural mesotheliomas, 12.5% of peritoneal mesotheliomas). Pleural fibrosis only was detected in 17% of cases of pleural mesothelioma and 27% of cases of peritoneal mesothelioma. Most patients had both parenchymal and pleural fibrosis. Although these results tend to indicate that in peritoneal mesothelioma the proportion of pleural fibrosis is significantly higher, these findings might have been due to the fact that in most cases of pleural mesothelioma non-malignant changes were interpreted in one hemithorax only. In 46 cases (21 pleural, 25 peritoneal) in which sufficient lung tissue was available histopathology of lung parenchyma indicated the presence of interstitial fibrosis; in 20 (43.5%) of these the chest x ray film had been read as negative. Thus the absence of radiologically detectable small opacities on the chest x ray film does not exclude the existence of interstitial pulmonary fibrosis in cases of mesothelioma among insulation workers. With lower levels of exposure (such as in family contacts of asbestos workers) it is conceivable that mesothelioma might occur in the absence of interstitial pulmonary fibrosis.
Occupation and male lung cancer: a case-control study in northern Sweden. L.A. Damber, L.G. Larsson. 1987;44(7):446-53. PubMed · Publisher · Free full text

Abstract

Using a case-control study comprising about 600 men with lung cancer in northern Sweden the potential risk of different occupations and groups of occupations was studied. Longitudinal data concerning occupation, employment, and smoking habits were obtained by questionnaires. Some occupational groups (underground miners, copper smelter workers, electricians, and plumbers) exposed to previously known lung carcinogenic agents such as radon daughters, arsenic, and asbestos, had considerably increased odds ratios, which persisted after adjustment for smoking. A slightly raised odds ratio was observed in a group of blue collar workers potentially exposed to lung carcinogenic agents; this rise in the group as a whole mainly disappeared after adjustment for smoking. Farmers and foresters had strikingly low odds ratios, which could only partly be explained by their more moderate smoking habits. The population aetiological fraction attributable to occupation was estimated as 9%.
Population based mortality surveillance in carbon products manufacturing plants. M.J. Teta, M.G. Ott, A.R. Schnatter. 1987;44(5):344-50. PubMed · Publisher · Free full text

Abstract

The utility of a population based, corporate wide mortality surveillance system was evaluated after a 10 year observation period of one of the company's divisions. The subject population, 2219 white male, long term employees from Union Carbide Corporation's carbon based electrode and specialty products operations, was followed up for mortality from 1974 to 1983. External comparisons with the United States male population were supplemented with internal comparisons among subgroups of the study population, defined by broad job categories and time related variables, adjusting for important correlates of the healthy worker effect. Significant deficits of deaths were observed for all causes and the major non-cancer causes of death. The numbers of deaths due to malignant neoplasms and respiratory cancer were less than, but not statistically different from, expected. There was a non-significant excess of deaths from lymphopoietic cancer, occurring predominantly among salaried employees. When specific locations were examined, operations with potential exposure to coal tar products exhibited a mortality pattern similar to that of the total cohort. The risk for lung cancer was significantly raised (five observed, 1.4 expected) in one small, but older, location which did not involve coal tar products during the period of employment of these individuals, but which historically used asbestos materials for several unique applications. Although these findings are limited by small numbers and a short observation period, the population based surveillance strategy has provided valuable information regarding the mortality experience of the population, directions for future research, and the allocation of epidemiological resources.
Possibility of inducing glandular stomach cancer in rats exposed to asbestos. F.M. Kogan, N.N. Vanchugova, V.N. Frasch. 1987;44(10):682-6. PubMed · Publisher · Free full text

Abstract

The possibility of glandular stomach cancer being induced was studied in 75 random bred white rats exposed to chrysotile asbestos. A perforated polyethylene capsule containing 100 mg asbestos and filler (beef fat and natural wax mixture 1:1) was introduced in an artificial bag placed on the greater curvature of the stomach. A capsule containing filler only was introduced in a similar way in 40 control rats. In the following 25 months, 18 tumors of the stomach and abdominal cavity were found in the rats treated with asbestos (eight adenomas, two adenocarcinomas, one carcinosarcoma, one forestomach cancer, one intestinal adenocarcinoma, two peritoneal mesotheliomas, and three abdominal lymphoreticulosarcomas.) Among the control rats no such tumors were found. The results of the experiment are discussed in connection with epidemiological data on stomach cancer in asbestos workers.
Pulmonary fibrosis in asbestos insulation workers with lung cancer. Y. Suzuki, H. Kipen, R. Lilis, et al. 1987;44(10):719-20. Letter PubMed · Publisher · Free full text

Summary

This letter was the authors' reply to a letter by Rudd (Br J Ind Med 1987;44:428-9) about their study of pulmonary fibrosis in asbestos insulation workers with lung cancer. The authors explained that lung parenchyma sections had been submitted for review by pathologists at various institutions in the United States and Canada, often from unspecified parts of the lung. Diffuse interstitial fibrosis had been sought in all available parenchyma. They rejected Rudd's proposal to exclude subpleural areas, saying there were no data showing that this parenchyma differed and that it often held a considerable concentration of asbestos fibres. They restated that one or more asbestos bodies had been seen in 130 of 138 cases. They argued that bodies may be absent from single thin (5 μm) sections even when present in the lung, and that detection depended on the amount of tissue, section thickness, tissue digestion, fibre type and fibre size. They expressed surprise that in the United Kingdom fibrosis with "too few" asbestos bodies was often classed as cryptogenic fibrosing alveolitis. They said uncoated fibres, seen only by electron microscopy, were likely present in the few cases without bodies. They declined to advise UK compensation agencies and noted Rudd's statement that he did not suggest the fibrosis was not caused by asbestos.

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Pulmonary fibrosis in asbestos insulation workers with lung cancer: a radiological and histopathological evaluation. H.M. Kipen, R. Lilis, Y. Suzuki, et al. 1987;44(2):96-100. PubMed · Publisher · Free full text

Abstract

This study was undertaken to determine the relation between radiographic and histological manifestations of pulmonary asbestosis (interstitial fibrosis) in insulation workers who had died of lung cancer. Of 450 confirmed deaths from lung cancer a chest radiograph suitable for determining evidence of pneumoconiosis was obtained in 219. Of these cases, 138 also had a tissue specimen submitted that was suitable for histological study to determine the extent of histological fibrosis. There was a significant albeit limited correlation between the radiographic and histological findings (r = 0.27, p less than 0.0013). All 138 cases had histological evidence of parenchymal fibrosis; in 25 (18%), however, there was no radiographic evidence of parenchymal fibrosis. In 10 cases (7%) both parenchymal and pleural disease were undetectable on the radiograph. Thus a negative chest radiograph does not exclude the presence of interstitial fibrosis (asbestosis) in a substantial proportion of insulation workers previously exposed to asbestos who develop lung cancer.
Relation between lung function, exercise capacity, and exposure to asbestos cement. P. Wollmer, L. Eriksson, B. Jonson, et al. 1987;44(8):542-9. PubMed · Publisher · Free full text

Abstract

A group of 137 male workers with known exposure (mean 20 fibre years per millilitre) to asbestos cement who had symptoms or signs of pulmonary disease was studied together with a reference group of 49 healthy industrial workers with no exposure to asbestos. Lung function measurements were made at rest and during exercise. Evidence of lung fibrosis was found as well as of obstructive airways disease in the exposed group compared with the reference group. Asbestos cement exposure was related to variables reflecting lung fibrosis but not to variables reflecting airflow obstruction. Smoking was related to variables reflecting obstructive lung disease. Exercise capacity was reduced in the exposed workers and was related to smoking and to lung function variables, reflecting obstructive airways disease. There was no significant correlation between exercise capacity and exposure to asbestos cement.
Sister chromatid exchanges in rat pleural mesothelial cells treated with crocidolite, attapulgite, or benzo 3-4 pyrene. S. Achard, M. Perderiset, M.C. Jaurand. 1987;44(4):281-3. PubMed · Publisher · Free full text

Summary

The authors tested whether attapulgite fibres induced sister chromatid exchanges (SCEs) in cultured rat pleural mesothelial cells. They described these cells as target cells in fibre-related diseases. They compared the effects with crocidolite asbestos fibres and with benzo 3-4 pyrene (BP), a known mutagen. The attapulgite sample came from Senegal and had fibres shorter than 2 µm. The crocidolite was a Union Internationale contre le Cancer sample. Cells between the 12th and 15th passage were treated with 10, 15 or 20 µg/ml of fibres for 48 hours, or with 0.5 µg/ml BP dissolved in dimethyl sulphoxide (DMSO) or acetone for different periods. Cells were then incubated with 5-bromodeoxyuridine for 70 hours. Thirty metaphases were scored per condition, and groups were compared with the Mann-Whitney test. Attapulgite did not significantly increase SCEs at 10 or 20 µg/ml, although electron microscopy showed fibres inside the cells. Crocidolite significantly increased SCEs at all doses, by about 30% at 10 µg/ml and 40% at 15 µg/ml. The effect was lower at 20 µg/ml, which the authors suggested could be related to cytotoxicity. BP increased SCEs in both solvents, by 300% after 30 hours. The effect was stronger in acetone, and acetone alone produced a significant rise at 48 hours. The authors concluded that this short-fibre attapulgite did not induce SCEs, whereas crocidolite did. They considered both findings consistent with animal carcinogenicity data.

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Unusual mortality pattern among short term workers in the perfumery industry in Geneva. E. Gubéran, M. Usel. 1987;44(9):595-601. PubMed · Publisher · Free full text

Abstract

A cohort of 537 workers employed for less than one year between 1900 and 1964 in the Geneva perfumery industry was followed up from entry to the end of 1983. During the period of study, 251 workers died and 41 (8%) were lost to follow up. The standardised mortality ratio (SMR) was significantly above 100 for all causes (SMR = 120), all cancers (SMR = 127), lung cancer (SMR = 186), and violent death (SMR = 179). The highest SMR from all causes was associated with the shortest period of employment (less than two months) and it decreased significantly with longer duration. Such mortality excesses had not been recorded among the 1168 workers of the same industry employed one year or more, previously studied in similar fashion. Interviews among a random sample of 52 workers employed for less than two months seem to indicate that the prevalence of smoking, exposures to asbestos, and occupational accidents in other hazardous industries were higher for these workers than for the reference population. Furthermore, unmarried men were overrepresented among the study cohort. These findings support previous observations indicating that short term workers share atypical features related to high mortality from various causes. It is suggested that mortality in this subgroup should be analysed separately in occupational studies.
Ventilatory function in rubber processing workers: acute changes over the workshift. M. Governa, M. Comai, M. Valentino, et al. 1987;44(2):83-9. PubMed · Publisher · Free full text

Abstract

When considering rubber tyre manufacturing from an occupational health viewpoint, three areas may be identified in which exposure to respirable materials are potentially harmful: the processing, curing, and talc areas. A study of the ventilatory function of the entire work force employed in the processing area in a rubber tyre manufacturing plant was undertaken to determine whether an acute reduction in lung function occurs over the course of their working shift (the plant worked a three shift system) and whether a chronic exposure to the occupational airborne contaminants causes permanent changes in lung function. The ventilatory function was measured at the worksite at the beginning and immediately after the end of the workshift. No evidence of chronic obstructive pulmonary disease was found and in most cases no significant decline in FEV1 was observed. Only one of the 79 individuals showed a moderate obstruction, measured by the ratio FEV1/FVC which gave the value of 0.55, with no variation over the shift. For non-smokers, the FVC, FEV1, and FEF25-75% were lower in those exposed for more than five years than in those exposed for five years or less. A similar pattern was also observed in the FVC and FEV1 of the smokers. None of these differences was statistically significant. Within each exposure group the pulmonary function of the smokers was lower than that of the non-smokers, but the only significant difference was found in the values of FEF25-75%. Only one man showed a decline in the FEV1/FVC ratio over the shift, but during each shift, a decrease in all the lung function tests was observed. The decrease was smallest during the first of the three shifts. These results are thought to support the hypothesis that there are acute adverse effects over an eight hour shift. Further investigations are needed to discover whether these acute changes in lung function result from a chemical stimulation or irritant receptors in the airways.
A survey of cancer and occupation in young and middle aged men. I. Cancers of the respiratory tract. D. Coggon, B. Pannett, C. Osmond, et al. 1986;43(5):332-8. PubMed · Publisher · Free full text

Abstract

In a search for clues to previously industrial carcinogens the occupational and smoking histories of young and middle aged men with different types of cancer were compared. The study population comprised men aged 18-54 and resident in the counties of Cleveland, Humberside, and Cheshire (including the Wirral). From hospital and cancer registration records 2942 members of the study population in whom cancers were diagnosed during the period 1975-80 were identified retrospectively. The occupational and smoking histories of these patients were sought by a postal questionnaire addressed either to the patients themselves or, if they had died, to their next of kin. The overall response rate to the questionnaire was 52.1%. Additionally, limited occupational information was obtained for 89% of cases from their hospital notes. Analysis of these data suggests that no serious bias arose as a consequence of the incomplete response to the questionnaire. This paper concentrates on the results for cancers of the respiratory tract and mesothelioma. Mesothelioma was found to cluster in laggers, electricians, and shipyard workers, and nasal carcinoma in woodworkers. Carcinomas of the larynx and of the bronchus were examined by formal statistical techniques, each being compared with a control group made up of all other cancers combined. Several interesting occupational and industrial associations were shown, in particular, an excess of bronchial carcinoma in the leather industry (RR = 2.6, CI 1.2-6.0), in building labourers (RR = 1.7, CI 1.0-2.9) and other construction workers (RR = 1.8, CI 1.0-3.0), in bakers and pastry cooks (RR = 3.6, CI 1.3-10.4). and in cooks (RR = 2.5, CI 1.2-5.1). In addition, a small cluster of lung tumours was observed in men who had worked as dental mechanics.
A threshold for asbestos related lung cancer. K. Browne. 1986;43(8):556-8. PubMed · Publisher · Free full text
Acrylamide cohort mortality study. W. Sobel, G.G. Bond, T.W. Parsons, et al. 1986;43(11):785-8. PubMed · Publisher · Free full text

Abstract

The mortality experience of 371 employees assigned to acrylamide monomer and polymerisation operations was examined with particular emphasis on cancers at sites identified from animal studies such as the central nervous system, thyroid gland, other endocrine glands, and mesotheliomas. A total of 29 deaths was observed up until 1982 (38.0 expected). No statistically significant excesses were noted in the total cohort and no deaths were found for the hypothesised sites of cancer. The observed deaths in the total cohort for the all cancers category were somewhat in excess (11 v 7.9); however, this was due entirely to excess cancers of the digestive tract and respiratory system in the subgroup with previous exposure to organic dyes. Among those employees not exposed to organic dyes, four deaths were due to malignancies versus 6.5 expected. This study does not support a cause effect relation between exposure to acrylamide at this work site and overall mortality, total malignant neoplasms, or any specific cancers.
Asbestos content of lung tissue in asbestos associated diseases: a study of 110 cases. V.L. Roggli, P.C. Pratt, A.R. Brody. 1986;43(1):18-28. PubMed · Publisher · Free full text

Abstract

Diseases associated with asbestos exposure include asbestosis, malignant mesothelioma, carcinoma of the lung, and parietal pleural plaques. In this study the asbestos content of lung tissue was examined in groups of cases representing each of these diseases and in several cases with non-occupational idiopathic pulmonary fibrosis. Asbestos bodies (AB), which are the hallmark of asbestos exposure, were present in the lungs of virtually everyone in the general population and present at increased levels in individuals with asbestos associated diseases. The highest numbers of AB occurred in individuals with asbestosis, all of whom had levels greater than or equal to 2000 ABs/g wet lung tissue. Every case with a content of 100,000 ABs/g or higher had asbestosis. Intermediate levels occurred in individuals with malignant mesothelioma and the lowest levels in patients with parietal pleural plaques. There was no overlap between the asbestos content of lung tissue from patients with asbestosis and those with idiopathic pulmonary fibrosis. Lung cancer was present in half the patients with asbestosis, and the distribution of histological patterns did not differ from that in patients with lung cancer without asbestosis. The asbestos body content in patients with lung cancer was highly variable. Control cases had values within our previously established normal range (0-20 ABs/g). There was a significant correlation (p less than 0.001) between AB counted by light microscope and AB and uncoated fibres counted by scanning electron microscopy. The previous observation that the vast majority of asbestos bodies isolated from human tissues have an amphibole core was confirmed.
Asbestos fibres in bronchoalveolar lavage fluid from asbestos workers: examination by electron microscopy. A.R. Gellert, J.Y. Kitajewska, S. Uthayakumar, et al. 1986;43(3):170-6. PubMed · Publisher · Free full text

Abstract

The uncoated and coated fibre load in bronchoalveolar lavage (BAL) fluid was assessed using light microscopy, scanning electron microscopy, and x ray microanalysis in 15 subjects with previous, unprotected exposure to asbestos, including three with clinical and radiological evidence of asbestosis, and in 13 urban dwelling control subjects with no known occupational exposure to asbestos. The mean ferruginous body count per ml BAL fluid in asbestos exposed subjects as determined by light microscopy was 52 (range 0-333). No ferruginous bodies were detected in control subjects. The mean fibre count per ml BAL fluid in asbestos exposed subjects as determined by electron microscopy was 793 (133-3700), significantly greater than 239 (44-544) in controls (p less than 0.05). Electron microscopic counts correlated with duration of previous exposure to asbestos (r = 0.47, p less than 0.05) and with percentage neutrophil counts (r = 0.53, p less than 0.025). There was no relation between electron microscopic fibre counts and light microscopic ferruginous body counts. In 11 asbestos exposed cases x ray microanalysis confirmed the presence of asbestos and in six the asbestos fibre type was clearly identified. Of five subjects showing no asbestos bodies by light microscopy, all showed fibres by electron microscopy, and in three cases the presence of asbestos was confirmed by microanalysis. Among control subjects, fibres were either large organic fibres or smaller particles which microanalysis showed were not asbestos. In only one control case were a few fibres identified which were confirmed as asbestos fibres on microanalysis. Electron microscopic examination of BAL fluid may confirm past exposure to asbestos and probably gives a crude quantitative estimate of asbestos load.
Biliary tract cancer and occupation in Sweden. H.S. Malker, J.K. McLaughlin, B.K. Malker, et al. 1986;43(4):257-62. PubMed · Publisher · Free full text

Abstract

Using the Cancer-Environment Registry, which links the incidence of cancer (1961-79) and the 1960 census data on industry and occupation for all employed individuals in Sweden, the occurrence of biliary tract cancer (ICD 7th rev 155.1-.9) was systematically assessed according to occupational and industrial classifications. Data are presented separately for cancer of the gall bladder (ICD 155.1) and other cancers of the biliary tract (ICD 155.2-.9) including cancers of the extrahepatic bile ducts, ampulla of Vater, and unspecified bile passages. Statistically significant increased risks for cancer of the gall bladder were observed for men employed in petroleum refining, papermills, chemical processing, shoemaking, and repairing, and for both men and women employed in textile work. A significant increase in the incidence of other cancers of the biliary tract (mostly cancers of the bile duct) was found for such asbestos related employment as shipbuilding and in the wholesale construction materials industry and among insulation workers. These findings should be considered only as clues to aetiological factors, although several are consistent with earlier observations from other countries.
Cohort study of mortality of vermiculite miners exposed to tremolite. J.C. McDonald, A.D. McDonald, B. Armstrong, et al. 1986;43(7):436-44. PubMed · Publisher · Free full text

Abstract

A cohort of 406 men employed before 1963 for at least one year in a vermiculite mine in Montana was followed up until July 1983. The vermiculite ore as fed to the mill contained 4-6% of amphibole fibre in the tremolite series. Vital status was established in all but one of the 406 and death certificates were obtained and coded for 163 of the 165 men who died. Compared with white men in the United States, the cohort experienced excess mortality from all causes (SMR 1.17), respiratory cancer (SMR 2.45), non-malignant respiratory disease (SMR 2.55), and accidents (SMR 2.14). Four deaths were from malignant mesothelioma (proportional mortality 2.4%). Compared with Montana death rates, the SMR for respiratory cancer was somewhat higher (3.03). Man-year analyses of respiratory cancer and estimated cumulative exposure gave a relation that did not depart significantly from linearity. The results of this and case-referent analyses indicate an increased risk of mortality from respiratory cancer in this cohort of about 1% for each fibre year of exposure. In relation to estimated exposure the mortality experienced by the cohort from both lung cancer and mesothelial tumours was higher than in chrysotile mining.
Correlation between fibre content of the lungs and disease in naval dockyard workers. J.C. Wagner, C.B. Moncrieff, R. Coles, et al. 1986;43(6):391-5. PubMed · Publisher · Free full text

Abstract

In the period 1966-82 lungs from 333 workers who had been employed at a Royal Naval dockyard were referred to the MRC Pneumoconiosis Unit where they were investigated for the severity of asbestosis, the presence of tumours, and an assessment of mineral fibre content and the type and amount of mineral present. The occupational exposure to mineral dust has been coded for 189 of these cases. There is good correlation between the severity of asbestosis and the coded exposures, electron microscopic mineral fibre count, and the fibre count as seen under the light microscope. The information collected showed that mesotheliomas occurred in those who had had minimal or slight asbestosis, by contrast with the pulmonary carcinomas found in those with moderate to severe asbestosis. The amphibole (crocidolite and amosite) lung content correlated with severity of asbestosis.
Follow up study of workers manufacturing chrysotile asbestos cement products. M.J. Gardner, P.D. Winter, B. Pannett, et al. 1986;43(11):726-32. PubMed · Publisher · Free full text

Abstract

A cohort study has been carried out of 2167 subjects employed between 1941 and 1983 at an asbestos cement factory in England. The production process incorporated the use of chrysotile asbestos fibre only, except for a small amount of amosite during four months in 1976. Measured airborne fibre concentrations available since 1970 from personal samplers showed mean levels below 1 fibre/ml, although higher levels had probably occurred previously in certain areas of the factory. No excess of lung cancer was observed in the mortality follow up by comparison with either national or local death rates, and analyses of subgroups of the workforce by job, exposure level, duration of employment, duration since entry, or calendar years of employment gave no real suggestion of an asbestos related excess for this cause of death. There was one death from pleural mesothelioma and one with asbestosis mentioned as an associated cause on the death certificate, but neither is thought to be linked to asbestos exposure at this factory. Other suggested asbestos related cancers, such as laryngeal and gastrointestinal, did not show raised risks. Although the durations of exposure were short in this study, the findings are consistent with two other studies of workers exposed to low concentrations of chrysotile fibre in the manufacture of asbestos cement products which reported no excess mortality.
Hazards of lung biopsy in asbestos workers. Y. Lerman, J. Ribak, I.J. Selikoff. 1986;43(3):165-9. Case report PubMed · Publisher · Free full text

Abstract

An investigation into the problem of the frequency and hazards of lung biopsy in asbestos workers was performed in two ways. The first study was into the frequency of lung biopsy among 2907 long term asbestos insulation workers in 1981-3 and the second was into the frequency of fatal complications of lung biopsy in 168 deaths from asbestosis among 2271 consecutive deaths of asbestos insulation workers 1967-76. Only 25 (0.9%) of the 2907 asbestos insulation workers reported having had either an open lung biopsy, a needle biopsy, or a transbronchial biopsy. Seven (24%) of these men suffered difficulties as a result of the biopsy. Lung biopsies had been performed on 14 of the 168 workers who died of asbestosis. Three (21%) of these 14 patients had died within 30 days of biopsy as a direct result of the procedure. In most cases there is no need for lung biopsy to establish a diagnosis of asbestosis; generally, it may be defined by history of exposure, clinical and radiological findings, and other well established non-invasive diagnostic procedures. Certainly, legal and compensation recommendation for biopsy should be considered with the possibility of death in mind. If biopsy is performed precautions should be taken, including adequate observation in hospital.
Incidence of cancer among workers producing calcium carbide. H. Kjuus, A. Andersen, S. Langård. 1986;43(4):237-42. PubMed · Publisher · Free full text

Abstract

The overall mortality and the incidence of cancer have been studied among male employees at a plant producing calcium carbide. The cohort was defined as all men employed at the plant for at least 18 months in the period 1953 to 1970 and was classified according to 10 occupational categories. The 790 men have been observed from 1953 to 1983 and the incidence of cancer in the cohort has been compared with national incidence rates. A significant excess of colonic cancer (standardised incidence ratio, SIR = 2.09) and of prostatic cancer (SIR = 1.78) was found, and also a slight excess of lung cancer among furnace and maintenance workers (SIR = 1.56). The possible exposure of the workers to polycyclic aromatic hydrocarbons, asbestos, and cadmium is discussed.
Is asbestos or asbestosis the cause of the increased risk of lung cancer in asbestos workers?. K. Browne. 1986;43(3):145-9. Editorial · Review PubMed · Publisher · Free full text

Summary

This editorial examined whether the excess lung cancer risk in asbestos workers is caused by asbestos itself or by asbestosis, the lung fibrosis it produces. The question was posed in the 1938 report of the Chief Inspector of Factories, which found lung cancer in 12 of 103 fatal asbestosis cases. The author reviewed evidence from pathology, animal experiments, in vitro studies, radiology and epidemiology. He noted reports that lung cancers in asbestos workers more often arose in the lower lobes and were more often adenocarcinomas. In one rat inhalation experiment, 6 tumours (3.8%) occurred in 157 rats without asbestosis, against 11 (25%) in 44 rats with the same exposure that developed asbestosis. A short-fibre amosite sample produced neither asbestosis nor excess tumours. In vitro evidence suggested that asbestos may act as a tumour promoter rather than a complete carcinogen. In Canadian chrysotile miners, the lung cancer SMR was 1.08 in men whose last radiograph was normal and 3.5 in those with abnormal radiographs. Using a numerical example, the author argued that errors in exposure estimates can make a threshold response appear linear. He cited several lower-exposure cohorts without raised lung cancer rates. He concluded that a threshold seemed probable and that asbestosis, rather than asbestos itself, probably prepares the soil for malignancy, but that a definitive answer was still awaited.

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 of asbestos workers in England and Wales 1971-81. J.T. Hodgson, R.D. Jones. 1986;43(3):158-64. PubMed · Publisher · Free full text

Abstract

A national study of British asbestos workers is briefly described and the mortality experience of 31 150 male asbestos workers in England and Wales who had been medically examined at least once as part of that survey is presented. The survey population is divided into workers with occupational exposure to asbestos before the inception of the 1969 Asbestos Regulations and those who worked with asbestos only after 1969. Of the 1128 who had died, 897 had worked before 1969; 34 of the death certificates received for these men mentioned mesothelioma and for another nine asbestosis was reported in the absence of mesothelioma or lung cancer. A statistically significant excess of lung cancer (SMR 136) was found. For the post-1969 workers, one case of asbestosis and one case of mesothelioma were reported, but further investigation of these cases showed probable occupational exposure to asbestos many years before 1969. The time from first exposure for this section of the population is too short to exclude an excess of asbestos related disease. The most noticeable excess of asbestos related disease was seen among the insulation workers who had more than twice (SMR 256) the expected number of deaths from lung cancer, and for whom almost 10% of all death certificates mentioned mesothelioma. No excess of any alimentary tract cancer was found and the population showed a significant deficit of large bowel cancer mortality (SMR 54).
Phenotypic characterisation of peripheral blood lymphoid cells in people exposed to fibrous zeolite. M. Ozesmi, A. Karlsson-Parra, G. Hillerdal, et al. 1986;43(12):830-3. PubMed · Publisher · Free full text

Abstract

Among inhabitants of the village of Karain in Turkey there is an extremely high incidence of malignant mesothelioma, most probably due to exposure to erionite, which is a fibrous zeolite and similar in appearance and properties to asbestos. This mineral may be found in the dust in the village. To characterise possible disturbances in the immune system of people exposed to fibrous zeolite, a phenotypic characterisation of lymphoid cells in the peripheral blood of 74 immigrants to Sweden from Karain was performed. Compared with normal controls, the mean percentages of Leu 4+ cells (Pan-T) and Leu 3a+ cells ("helper/inducer" T cells) were significantly decreased, whereas the mean percentage of Leu 2a+ cells ("suppressor/cytotoxic" T cells) was normal, leading to a significant reduction of the Leu 3a/Leu 2a subset ratio. The percentage of B cells (Leu 12+ cells) was significantly increased, whereas the percentages of both HLA-DR+ and HLA-DQ+ cells were normal. The percentage of natural killer cells (NK) and killer (K) cells as defined by the monoclonal anti-Leu 7 and anti-Leu 11b were also normal. These findings indicate that exposure to fibrous zeolite causes a numerical imbalance between the two phenotypically different T cell subsets similar to that seen in asbestos exposed individuals.
Prevalence of radiographic asbestosis in crocidolite miners and millers at Wittenoom, Western Australia. W.O. Cookson, N.H. De Klerk, A.W. Musk, et al. 1986;43(7):450-7. PubMed · Publisher · Free full text

Abstract

An estimate has been made of the prevalence of unrecognised pneumoconiosis in former crocidolite workers from Wittenoom, Western Australia. All plain chest radiographs relating to a one in six random sample (1025 men) of all former Wittenoom workers who had never entered a compensation claim to the Pneumoconiosis Medical Board of Western Australia were sought from Perth teaching hospitals and from the Perth Chest Clinic where compulsory examination of all workers in the mining industry takes place. Radiographs were recovered for 83% of the men and read independently by two observers. By means of logistic regression analysis a current prevalence of parenchymal abnormality (defined as a radiographic profusion of small opacities of category 1/0 or greater on the ILO classification) of nearly 20% was calculated after adjustment for age, time since first exposure, and cumulative exposure level. One hundred men randomly selected from those known to be alive in the sample were invited to attend for a new radiographic examination. Seventy four men attended and the predicted prevalence was confirmed. It is estimated from these data that there were between 450 and 900 former Wittenoom workers in Australia at the end of 1980 who had radiographic abnormality consistent with pneumoconiosis but had not claimed compensation or had asbestosis diagnosed. The data are consistent with there being no threshold dose of crocidolite exposure for the development of radiographic abnormality in this group.
Pulmonary function in asbestos cement workers: a dose-response study. M. Finkelstein. 1986;43(6):406-13. PubMed · Publisher · Free full text

Abstract

This study has found that residence time weighted exposure (asbestos dose) may be used to model the risk and extent of pulmonary function abnormalities in a cohort of asbestos cement workers. This parameter, which incorporates both exposure concentration and latency, had previously proved useful for modelling the risk of radiographic abnormalities in this cohort. Asbestos dose and smoking were independent and additive contributors to decreased pulmonary function. It was also found that lung function results could be used as surrogates for dose in the assessment of mortality risk in this cohort.
Radiological survey of past and present vermiculite miners exposed to tremolite. J.C. McDonald, P. Sebastien, B. Armstrong. 1986;43(7):445-9. PubMed · Publisher · Free full text

Abstract

Chest radiographs taken by a standard technique were obtained from 173 current employees (164 men, 9 women) of a vermiculite mine in Montana, from 80 of 110 past employees resident within 200 miles, and from 47 men from the same area without known exposure to dust. In 43 of the 80 and 24 of the 47 an earlier chest x ray film was retrieved from the hospital archives. All 367 films were assessed blind and independently by three experienced readers using the ILO 1980 classification. Median radiographic assessment scores were analysed in relation to estimated cumulative exposure to the amphibole fibres that contaminate the vermiculite. Logistic regression analyses showed independent effects of age, smoking, and exposure on the prevalence of small opacities and of age and probably of exposure on pleural thickening. Overall, the data suggest that by retirement age the increase in prevalence of small opacities (greater than or equal to 1/0) lies between 5% and 10% per 100 f/ml years. This gradient may be somewhat steeper than for chrysotile miners and millers, but not much so.
Relation between pathological grading and lung fibre concentration in a patient with asbestosis. B. Gylseth, V. Skaug. 1986;43(11):754-9. Case report PubMed · Publisher · Free full text

Abstract

The fibre concentration and extent and severity of fibrosis have been analysed in 48 specimens from the left lung of a patient with asbestosis. Two different methods of fibre analysis were used. The results obtained by transmission electron microscopy were 2-2.5 times higher than those obtained by scanning electron microscopy. Low temperature ashed samples showed on average twice the number of fibres obtained after wet digestion of the samples. The transmission electron microscope detected considerably shorter fibres than the scanning electron microscope. Low temperature ashing produced also shorter fibres compared with the wet digestion procedure. A statistically significant correlation between fibre concentration and the grade of fibrosis was found only for low temperature ashed samples analysed in the transmission electron microscope. When dividing the lung into nine anatomical compartments and pooling the grade of fibrosis and the fibre concentration data within each compartment, an even better correlation was obtained.
A job-exposure matrix for use in population based studies in England and Wales. B. Pannett, D. Coggon, E.D. Acheson. 1985;42(11):777-83. PubMed · Publisher · Free full text

Abstract

The job-exposure matrix described has been developed for use in population based studies of occupational morbidity and mortality in England and Wales. The job axis of the matrix is based on the Registrar General's 1966 classification of occupations and 1968 classification of industries, and comprises 669 job categories. The exposure axis is made up of 49 chemical, physical, and biological agents, most of which are known or suspected causes of occupational disease. In the body of the matrix associations between jobs and exposures are graded to four levels. The matrix has been applied to data from a case-control study of lung cancer in which occupational histories were elicited by means of a postal questionnaire. Estimates of exposure to five known or suspected carcinogens (asbestos, chromates, cutting oils, formaldehyde, and inhaled polycyclic aromatic hydrocarbons were compared with those obtained by detailed review of individual occupational histories. When the matrix was used exposures were attributed to jobs more frequently than on the basis of individual histories. Lung cancer was significantly more common among subjects classed by the matrix as having potential exposure to chromates, but neither method of assigning exposures produced statistically significant associations with asbestos or polycyclic aromatic hydrocarbons. Possible explanations for the failure to show a clear effect of these known carcinogens are discussed. The greater accuracy of exposures inferred directly from individual histories was reflected in steeper dose response curves for asbestos, chromates, and polycyclic aromatic hydrocarbons. The improvement over results obtained with the matrix, however, was not great. For occupational data of the type examined in this study, direct exposure estimates offer little advantage over those provided at lower cost by a matrix.
A spin label study of the effects of asbestos, quartz, and titanium dioxide dusts on the bovine erythrocyte membrane. W. Leyko, E. Gendek. 1985;42(4):281-4. PubMed · Publisher · Free full text

Abstract

The effects of five UICC asbestos samples, titanium dioxide, and quartz on the bovine red cell membrane have been studied in erythrocyte ghosts by the spin labelling technique. Analysis of the electron paramagnetic resonance (EPR) spectra of two sulphydryl reactive spin labels and one fatty acid spin label in red cell ghosts showed modifications in membrane protein after asbestos treatment but no alterations in membrane lipids. In experiments with quartz no membrane changes were noted but titanium dioxide altered the proteins bound with the protein reactive spin label used in the present study. The possible mechanism for these effects is discussed.
A study of dose-response relationships for asbestos associated disease. M.M. Finkelstein. 1985;42(5):319-25. PubMed · Publisher · Free full text

Abstract

The risk of an asbestos worker developing small irregular opacities on the chest radiograph is related to cumulative exposure to asbestos dust, latency, and smoking habit. In this study the use of residence-time weighted exposure as a "dose metric" was explored in a cohort of asbestos cement workers. It was found that this parameter, which incorporates both exposure concentration and latency, is useful for modelling the risk of small opacities and might also be useful for modelling the risk of mesothelioma.
Asymmetric rapidly progressive lung fibrosis: a cause of pseudotumour in asbestosis. W.O. Cookson, J.J. Glancy, F.A. Frost. 1985;42(5):350-3. Case report PubMed · Publisher · Free full text
Combined effect of asbestos and smoking on mortality from lung cancer and mesothelioma in factory workers. G. Berry, M.L. Newhouse, P. Antonis. 1985;42(1):12-8. PubMed · Publisher · Free full text

Abstract

The mortality of over 1250 male and 420 female asbestos factory workers was observed over the period 1971-80. Smoking habits were obtained from the subjects in 1971 before the start of the follow up period. Mortality due to lung cancer and to mesothelioma was related to smoking habits. After allowing for the effect of smoking on lung cancer the relative risk due to asbestos was highest for those who had never smoked, lowest for current smokers, and intermediate for ex-smokers; the trend was statistically significant (p less than 0.05). There was no significant association between smoking and deaths due to mesothelioma. Data from several studies are reviewed, and although overall non-smokers have a relative risk of lung cancer due to asbestos that is 1.8 times that of smokers, there is some uncertainty on the accuracy of this figure because of possible biases and sampling variation. Overall the evidence is that mesothelioma risk is independent of smoking.
Compensation, radiographic changes, and survival in applicants for asbestosis compensation. W.O. Cookson, A.W. Musk, J.J. Glancy, et al. 1985;42(7):461-8. PubMed · Publisher · Free full text

Abstract

The survival of 354 claimants for compensation for pulmonary asbestosis among former workers of the Wittenoom crocidolite mine and mill in Western Australia has been examined. There were 118 deaths up to December 1982. The median time between start of work and claim for compensation was 17 years. The standardised mortality ratio (SMR) for deaths from all causes was 2.65 (p less than 0.0001). The SMR for pneumoconiosis was 177.2 (p less than 0.0001), bronchitis and emphysema 2.6 (p = 0.04), tuberculosis 44.6 (p less than 0.0001), respiratory cancer (including five deaths from malignant pleural mesothelioma) 6.4 (p less than 0.0001), gastrointestinal cancer 1.6 (p = 0.22), all other cancers 1.6 (p = 0.17), heart disease 1.4 (p = 0.07), and all other causes 2.18 (p = 0.004). Plain chest radiographs taken within two years of claiming compensation were found for 238 subjects and were categorised independently by two observers according to the International Labour Organisation criteria without knowledge of exposure or compensation details. Profusion of radiographic opacities, age at claiming compensation, work in the Wittenoom mill, and degree of disability awarded by the pneumoconiosis medical board were significant predictors of survival, but total estimated exposure to asbestos was not. Radiographic profusion and degree of disability were, however, predictable by total exposure. The median survival from claim for compensation was 17 years in subjects with ILO category 1 pneumoconiosis, 12 years in category 2, and three years in category 3.
Kinetics of deposition and clearance of inhaled mineral dusts during chronic exposure. J.H. Vincent, A.M. Johnston, A.D. Jones, et al. 1985;42(10):707-15. PubMed · Publisher · Free full text

Abstract

New inhalation studies have been carried out with rats exposed to UICC (Union International Contre le Cancer) amosite asbestos, with the main aim of further elucidating the factors the influence the accumulation of dust in the lung during prolonged chronic exposure. The results show that, for exposure times beyond a few weeks, the lung burden rises linearly and does not level off as predicted by simple models based on ideas taken from the 1966 report of the Task Group on Lung Dynamics. Furthermore, the lung burden is found to scale directly in proportion to the exposure concentration in a way that seems to contradict the overload hypothesis stated earlier. Nevertheless, the general pattern exhibited by our results for asbestos is markedly similar to that found elsewhere for rats inhaling diesel fume, leading to the suggestion that it is general (and not specific to fibrous dust); and the hypothesis that, whereas overload of clearance can take place at high lung burdens after exposure has ceased, it is cancelled by the sustained stimulus to clearance mechanisms provided by the continuous challenge of chronic exposure. The linearity of the increase in lung burden is explained in terms of a kinetic model involving sequestration of some inhaled material to parts of the lung where it is difficult to clear. The particular sequestration model favoured is one where, the longer a particle remains in the lung without being cleared, the more likely it will be sequestrated (and therefore less likely cleared). It is believed that such ideas may eventually be useful in forming exposure-dose relations for epidemiology.
Lung cancer among asbestos cement workers. A Swedish cohort study and a review. C.G. Ohlson, C. Hogstedt. 1985;42(6):397-402. PubMed · Publisher · Free full text

Abstract

A cohort study of 1176 Swedish asbestos cement workers did not indicate any asbestos related excess mortality. Possible explanations of the negative outcome are relatively low exposure levels and the predominant use of chrysotile in production. Such a tentative conclusion is supported by a review of five mortality studies of workers exposed to asbestos cement that report considerable differences in relative risks for lung cancer. These differences could be explained by various degrees of cumulative exposure, the amount of amphiboles in the production, and methodological shortcomings. A median exposure of 10-20 fibre-years does not seem to cause an increased risk of lung cancer, particularly when only chrysotile is used.
Mesothelioma and asbestos fibre type. A.D. McDonald, J.C. McDonald. 1985;42(8):567-8. Letter PubMed · Publisher · Free full text
Modified nucleosides in asbestos workers at high risk of malignant disease: results of a preliminary study applying discriminant analysis. S.J. Solomon, A. Fischbein, O.K. Sharma, et al. 1985;42(8):560-2. PubMed · Publisher · Free full text

Abstract

Patients with asbestos related malignant mesothelioma excrete high levels of modified nucleosides in their urine. The purpose of the present report was to explore further the usefulness of measuring these breakdown products of transfer RNA (tRNA) in male asbestos insulation workers who are at high neoplastic risk but without clinical signs of malignancy. Modified nucleoside levels (psi, m'A, m'I, m2G, and ac4C) were used as discriminator variables in a computer generated discriminant function in which 96% of the controls and 95% of the insulation workers were correctly classified. It was also found, using a similar multiple regression model, that 10 of 13 were correctly classified as having normal chest radiographs and 27 of 30 asbestos exposed subjects as exhibiting alterations in either the parenchyma, pleura, or both. The results suggest that measuring modified nucleosides levels in the urine of asbestos exposed workers, and perhaps others exposed to carcinogenic agents, has the potential for identifying, through multivariate statistical techniques, individuals who are at high neoplastic risk.
Mortality of factory workers in east London 1933-80. M.L. Newhouse, G. Berry, J.C. Wagner. 1985;42(1):4-11. PubMed · Publisher · Free full text

Abstract

The mortality of 3000 male factory workers, 1400 laggers, and 700 women factory workers in east London has been studied. The men were first employed between 1933 and 1964, the women between 1936 and 1942. Textiles were produced until the late 1950s as well as other asbestos products. Laggers were employed on contract in increasing numbers in later years. Crocidolite asbestos was used until the late 1950s as well as asmosite and chrysotile. Exposure of workers was graded according to the job into two categories, low/moderate and severe, and subdivided by duration of employment up to two years or longer. Mesothelial tumours accounted for 7.5% of the total mortality in men, and 9% in women with their longer follow up period. Lung cancer accounted for 20% of deaths in men and 14% in women. Both mesothelial tumours and lung cancer showed a dose response relationship. Histopathological examination of a series of predominantly postmortem specimens showed 22% of adenocarcinomas of lung among men and 21% in women. There was an excess of gastrointestinal tumours but no dose response relationship could be shown. Among severely exposed male factory workers there was an excess of deaths from cancer of the larynx and among severely exposed women of carcinoma of the breast and ovary. Twenty four deaths (2%) were due to asbestosis. There is an indication that the incidence of mesothelial tumours is declining but a further period of observation is required for confirmation.
Mortality of welders and other craftsmen at a shipyard in NE England. M.L. Newhouse, D. Oakes, A.J. Woolley. 1985;42(6):406-10. PubMed · Publisher · Free full text

Abstract

Personnel records of over 1000 welders and electricians but only 235 caulkers and 557 platers employed at a shipyard in NE England between 1940 and 1968 were obtained and the mortality followed up to December 1982. The observed number of deaths (13 from mesothelial tumours, nine among the electricians) were compared with the number to be expected in the Newcastle connurbation. Welders and caulkers were most exposed to welding fumes, electricians to asbestos. The study was limited by the lack of accurate job exposure details, and there was no record of smoking habits, but welders and caulkers showed a higher standardised mortality ratio for all causes, lung cancer, ischaemic heart disease, pneumonia, and accidents than platers and electricians.
Mortality of workers in a French asbestos cement factory 1940-82. A.M. Alies-Patin, A.J. Valleron. 1985;42(4):219-25. PubMed · Publisher · Free full text

Abstract

The mortality of a complete cohort of 1506 French asbestos cement workers employed for at least five years is related to the time elapsed since first exposure. The mortality from all causes (analysed by the "man-years method") has been found to be above normal only in those subjects employed for more than 20 years, with more than 35 years of follow up. Standardised mortality ratios for cancers of all sites (ICD 140-209) and pulmonary cancer (ICD 162-163.0) have been assessed in subjects whose first exposure dates go back more than 20 years. Mortalities from cancer of all sites and from pulmonary cancer have been detected in excess in workers employed for more than 20 years and originally hired when aged 25 or under.
On the relative toxicity of asbestos fibres. M. Finkelstein. 1985;42(1):69-70. Letter PubMed · Publisher · Free full text
Reduced killer cell activity of lymphocytes from patients with asbestosis. M. Kubota, S. Kagamimori, K. Yokoyama, et al. 1985;42(4):276-80. PubMed · Publisher · Free full text

Abstract

Immunological abnormalities in 30 patients with asbestosis were investigated by examining the cytoxicity of natural killer (NK) cells and antibody dependent cellular cytotoxicity by killer (K) cells from peripheral blood lymphocytes; the effects of interferon on NK activity was also examined. Fifteen men and 15 women (mean age 58; range 40-72) with asbestosis but who were free of complications such as tuberculosis, carcinoma, or steroid treatment were the subjects for study. There were nine cases of type 1, 19 cases of type 2, and two cases of type 3 disease as described in the ILO classification of pneumoconiosis. They were all textile workers with a mean duration of 18 years (3-40 years) since first exposure to chrysotile. Controls matched for age and sex were selected from a population without occupational exposure to asbestos. The activity of the NK and K cells in patients with asbestosis was significantly lower than in the control group, but the populations of NK and K cells in the peripheral blood lymphocytes were not significantly different in the two groups. An in vitro experiment showed that the increase in the cytotoxicity of the NK cell after treatment with interferon-alpha was significantly lower in the subjects than in the controls. These results indicate that one of the defence mechanisms in relation to cancer is deficient in patients with asbestosis.
Relations between asbestos exposure and lung cancer SMRs in occupational cohort studies. F.D. Liddell, J.A. Hanley. 1985;42(6):389-96. PubMed · Publisher · Free full text

Abstract

It has long been accepted that excessive exposure to asbestos may produce lung cancer but not that there is a consistent "biological gradient." This can only be evaluated reliably in studies where, for every individual, exposure has been measured in terms of both duration and intensity. Even now, there are only at most eight such cohort studies of asbestos workers, while femoral methods of analysis have been available only recently. These methods, applied in these studies, yield good evidence that the "exposure-response" relation between accumulated exposure to asbestos and standardised mortality ratios (SMRs) for lung cancer may be taken as linear, but that at zero exposure the lung cancer SMR is not always unity--not surprising, because of well known difficulties with the choice of reference population and selection problems. This leads to a concept of "relative slopes" that take account of the background mortality in the cohort and make what appears to be the best use of the available data. Other approaches to the same data, and indeed to all cohort data known, are also considered. Each study is examined as closely as is possible in a short review, and the concepts of linearity and relative slopes appear justified. The relative slopes (b/a) in the line SMR = a[1 + (b/a) . (exposure)] vary much more widely than can be accounted for by differences in epidemiological methodology; as discussed elsewhere, reasons for the variation seem to lie rather in type and dimensions of asbestos fibre, industrial process, etc. Slopes in the line SMR = 1 + b1 . (exposure) vary about twice as much as do the relative slopes.
Severe diffuse small airways abnormalities in long term chrysotile asbestos miners. J.L. Wright, A. Churg. 1985;42(8):556-9. PubMed · Publisher · Free full text

Abstract

To determine the nature and extent of pathological changes in the small airways induced by asbestos, the pathological lesions of fibrosis and pigmentation of the membranous and respiratory bronchioles and alveolar ducts in lungs obtained from necropy from a group of 36 non-asbestotic long term chrysotile miners and 36 age, sex, and smoking matched controls who had no history of exposure to dust were compared. The airways were graded using a standard visual grading system. Appreciably greater airway fibrosis was found for all types of airway in the whole group of miners compared with the controls. Differences for pigmentation were generally similar but less pronounced. It is concluded that long term exposure to mineral dust as an asbestos miner produces severe diffuse pathological changes in the small airways; these findings may relate to the physiological observation of unusual degrees of airflow obstruction in this group of workers.
Ventilatory decrements in former asbestos cement workers: a four year follow up. C.G. Ohlson, L. Bodin, T. Rydman, et al. 1985;42(9):612-6. PubMed · Publisher · Free full text

Abstract

A four year follow up of the ventilatory function in former asbestos cement workers has been performed to determine whether any further decrease occurred after cessation of exposure. Seventy five of 125 subjects were eligible for re-examination and were compared with local referents. None showed signs of asbestosis but 32% had pleural plaques at the renewed examination. Cumulative asbestos exposure calculated as fibre x years had been estimated individually in the original examination. After adjustment for age, height, tracheal area, and smoking category the FVC and FEV1 for all exposed subjects were on average 7% v 6% less than predicted from the referents and twice as much for the subjects with the highest exposure. The four year declines in FVC and FEV1 were larger than in the referents, significantly so for FEV1. There were no significant correlations between pleural plaque and ventilatory function after adjustment for exposure. Thus the age adjusted reduction in ventilatory function had progressed during the follow up period despite the cessation of exposure and the lack of radiological signs of asbestosis.
A spin label study of the effect of chrysotile asbestos on erythrocyte membranes. E. Gendek, G. Bartosz, W. Leyko. 1984;41(1):46-50. PubMed · Publisher · Free full text

Abstract

Alterations in erythrocyte membranes caused by UICC B chrysotile asbestos fibres were studied in red cell ghosts using the spin label technique. The electron paramagnetic resonance (EPR) spectra of two sulphydryl reactive spin labels and one fatty acid spin probe in erythrocyte ghosts showed membrane protein modifications but no changes in lipid fluidity caused by the haemolytic chrysotile asbestos fibres.
Binding of environmental carcinogens to asbestos and mineral fibres. G. Harvey, M. Pagé, L. Dumas. 1984;41(3):396-400. PubMed · Publisher · Free full text

Abstract

A rapid method has been developed for measuring the binding capacity of asbestos and other mineral fibres for environmental carcinogens. Benzo(alpha)pyrene (B(alpha)P), nitrosonornicotine (NNN), and N-acetyl-2-aminofluorene (NAAF) were assayed in the presence of Canadian grade 4T30 chrysotile, chrysotile A, amosite, crocidolite, glass microfibres, glasswool, attapulgite, and titanium dioxide. Chrysotile binds significantly more carcinogens than the other mineral fibres. This binding assay is reproducible with coefficients of variation of less than 8% and 6% respectively for inter and intra assay. The influence of pH was also studied, and there is good correlation between the carcinogen binding and the charge of the tested mineral fibres. The in vitro cytotoxicity on macrophage like cell line P388D1 and the haemolytic activity of various mineral fibres were also measured; a good correlation was found between the binding capacity and the cytotoxicity of tested mineral fibres on P388D1 cells. These results give some explanations for the reported synergism between exposure to asbestos and the smoking habits of workers.
Cell population and histochemistry of asbestos related lesions of rat pleural cavity after injection of various inorganic dusts. R.E. Edwards, M.M. Wagner, C.B. Moncrieff. 1984;41(4):506-13. PubMed · Publisher · Free full text

Abstract

Rats injected intrapleurally with either crocidolite or chrysotile asbestos or silica or saline, were killed at intervals up to 2 years of age. The pleural cavities were washed out immediately after death and the washing used for enumerating cells. In addition tissue from granulomas and mesotheliomas was sectioned and stained for lysosomal enzymes. The total cellular response to silica found in the washout showed a pronounced increase when compared with either asbestos dust or controls; crocidolite gave a decreased response in an early group of the individual cells studied. The most important finding was a decrease in the number of mast cells found to be associated with the injection of both types of fibres. Crocidolite induced granulomas showed the presence of lysosomal enzymes and non-specific esterase in mononuclear cells and giant cells, even two years after injection. With chrysotile, giant cells were only present up to three to four months, and few positively staining cells were noted after 18 months. While the response of cells in the pleural cavity does not differ greatly between the two types of fibres, that in the granulomas highlights the longer lasting action of crocidolite.
Dust exposure and mortality in an American chrysotile asbestos friction products plant. A.D. McDonald, J.S. Fry, A.J. Woolley, et al. 1984;41(2):151-7. PubMed · Publisher · Free full text

Abstract

Cohort studies in three American asbestos factories were undertaken to investigate the effect of fibre type and manufacturing process on lung cancer, mesothelioma, and asbestosis. Reports have been published on a chrysotile textile plant in South Carolina and a mainly textile plant in Pennsylvania, which also used amphiboles. In the third plant in Connecticut friction products and packings were made from chrysotile only. In a cohort of 3641 men employed for one month or more, 1938-58, 3513 (96.5%) were traced, 1267 (36%) had died, and death certificates were obtained for 1228 (96.9%). Individual exposures were estimated (in mcpf . years) from impinger measurements. Life table analyses using Connecticut mortality rates gave an SMR for all causes of 108.5 (USA 107.9). The SMR (all causes) for men who had worked for less than a year was 129.9 and for those who had worked for a year or more, 101.2. The equivalent SMRs for respiratory cancer were 167.4 and 136.7 respectively. Excluding men who had worked for less than a year, there was possible evidence of some increase in risk of lung cancer with increasing exposure, supported also by a "log-rank" (case-control) analysis, of the same order as that observed in chrysotile mining and milling. These findings may be compared with chrysotile textile manufacture where the risk of lung cancer was some 50-fold greater. It is suggested that the differences in risk are perhaps related to the higher proportion of submicroscopic fibres in textile manufacture that may result from the traumatic carding , spinning, and weaving processes. No case of mesothelioma was found, consistent with a much lower risk of this tumour with chrysotile than with amphiboles. Twelve deaths (nine in men with very short and low asbestos exposure) were given ICD code 523 (pneumoconiosis); all but two were ascribed to anthracosilicosis or silicosis and none to asbestosis.
Histological types of malignant mesothelioma and asbestos exposure. W.E. Wright, R.P. Sherwin. 1984;41(4):514-7. PubMed · Publisher · Free full text

Abstract

The Los Angeles County Cancer Surveillance Program abstracts hospital pathology records on almost all cases of cancer occurring in the county. Those cases of pleural and peritoneal mesothelioma that occurred between 1972 and 1978 were identified. Occupational histories were obtained from interviews, and the histopathology of the tumours was reviewed by a member of a mesothelioma reference panel who was unaware of the exposure histories. The relation of asbestos exposure to the three histological types of mesothelioma (epithelial, mesenchymal, and mixed) was studied among the 29 cases for whom occupational histories were available and who were also considered to have histopathology consistent with mesothelioma. The proportion of cases exposed to asbestos was high for both the epithelial (11/17, 65%) and mixed histological types (6/11, 55%). The single case of mesothelioma classified as a mesenchymal type was also exposed to asbestos. Cases who had worked in shipyards were represented in each of the three groups. In cases who had worked in asbestos production and manufacture an exclusively epithelial type of tumour was observed. In cases who had worked as insulators or in heating trades the histological type was predominantly (3/4) mixed. These data do not support the hypothesis that any specific histological type of mesothelioma is especially related to asbestos exposure.
In vitro biodegradation of chrysotile fibres by alveolar macrophages and mesothelial cells in culture: comparison with a pH effect. M.C. Jaurand, A. Gaudichet, S. Halpern, et al. 1984;41(3):389-95. PubMed · Publisher · Free full text

Abstract

The modification of the chemistry of asbestos chrysotile fibres (Mg3(Si2O5)(OH)4) after their ingestion by cultured cells has been studied. Two types of cells involved in asbestos related pulmonary disease were used, rabbit alveolar macrophages (AM), recovered by bronchoalveolar lavage, and pleural mesothelial cells (PMC) obtained from the rat parietal pleura. Chemical characterisation of intracellular fibres was performed on unstained ultrathin sections by electron probe microanalysis. The results showed a progressive leaching of Mg, characterised by a time dependent decrease of Mg/Si. AM were more efficient than PMC at leaching intracellular chrysotile fibres since it took longer to obtain the same proportion of leached fibres with PMC than with AM. As in vitro Mg-leaching can be obtained by acid treatment, chrysotile fibres were incubated, either untreated or pretreated with cell membranes, at pH 4 or 7 for various times. The data show that the kinetic of leaching by AM was comparable with leaching at pH 4. The leaching by PMC was of the same order as leaching at pH 7. When membranes were adsorbed on to the fibres, a delayed leaching was observed. The results indicate that the solubilisation of chrysotile by AM could be an intraphagolysosomal event due to a pH effect. With PMC, however, it is not possible to draw this conclusion since nothing is known about the intracellular pH.
Malignant mesothelioma: incidence, asbestos exposure, and reclassification of histopathology. W.E. Wright, R.P. Sherwin, E.A. Dickson, et al. 1984;41(1):39-45. PubMed · Publisher · Free full text

Abstract

The Los Angeles County Cancer Surveillance Program abstracts records on almost all cases of cancer occurring in the county. In a study of those cases of pleural and peritoneal malignant mesothelioma (MM) that occurred from 1972 to 1979 occupational histories were obtained during interviews, and histopathology of the tumours was reviewed and classified by a member of a mesothelioma reference panel who was unaware of the exposure histories. About half the cases reviewed had likely exposure to asbestos at work. The greatest proportion of cases designated as MM by the pathologist occurred among individuals likely to have had the heaviest exposure of asbestos (42%). No upward trend of incidence over time was apparent among cases designated as MM. The age adjusted incidence rates for designated MM were lower than in other studies. The well recognised interobserver variability in diagnosing MM apparently produces raised estimates of incidence and an overestimate of trends of incidence. The interobserver variability may result from different awareness of MM occurrence, a lack of precise histopathological criteria for the diagnosis, or the influence of a history of exposure to asbestos on the interpretation. A history of exposure to asbestos may bias interpretation of histopathology and should not be used to make the histological diagnosis.
Pulmonary granulomatous reaction: talc pneumoconiosis or chronic sarcoidosis?. P. Tukiainen, J. Nickels, E. Taskinen, et al. 1984;41(1):84-7. Case report PubMed · Publisher · Free full text

Abstract

A chronic pulmonary granulomatous reaction was associated with an almost identical clinical picture in two patients exposed to talc. In both patients lung biopsy showed the deposition of talc particles and a heavy granulomatous reaction. At the time of diagnosis the Kveim test result was negative in both patients, urinary calcium excretion was normal, and there were no extrapulmonary manifestations and no response to steroid treatment. These findings point against sarcoidosis. The serum angiotensin-converting enzyme level, however, was raised in both patients. It was concluded that the patient who was exposed to talc in the rubber industry had a true talc pneumoconiosis. The other patient, who was exposed to cosmetic talcum powder, suffered from chronic sarcoidosis with talc deposition in the lungs, since an enlarged axillar lymph node containing granulomatous inflammation was discovered after two years' follow up. These cases show that it may be extremely difficult to differentiate between chronic sarcoidosis and talc pneumoconiosis even after careful clinical and histological analysis.
Quantitative x ray microanalysis of pulmonary mineral particles in a patient with pneumoconiosis and two primary lung tumours. S. Anttila, S. Sutinen, P. Pääkkö, et al. 1984;41(4):468-73. Case report PubMed · Publisher · Free full text

Abstract

The right upper lung lobe of a 74 year old man was resected for a central tumour. Two primary cancers were found; a central small cell carcinoma and a peripheral squamous cell carcinoma. In addition, the peripheral lung tissue showed generalised peribronchiolar fibrosis extending from the non-respiratory bronchioles to the level of the alveolar ducts. Abundant asbestos bodies and large amounts of black dust were seen around the bronchioles. Pulmonary mineral particles were studied by quantitative energy dispersive x ray microanalysis (EDS) using scanning transmission electron microscopy (STEM). The x ray spectra for mineral particles were measured in thin sections, and the characteristic peak intensities of the elements were converted to weight fractions (in oxides). The results enabled the minerals present to be identified and their presence confirmed by calculating the mineral formula. These originated from nine natural minerals, anthophyllite and chrysotile asbestos, talc, and quartz, feldspars, and muscovite, which are components of sand, and also from two artificial mullites used in fire clay. The exposure history of the patient explained the most likely origins of the minerals detected. The patient had been a mason for 23 years, repairing and demolishing stoves and fireplaces and using asbestos for insulation work.
Radiographic assessment of pleuropulmonary disease in asbestos workers: posteroanterior, four view films, and computed tomograms of the thorax. R. Bégin, M. Boctor, D. Bergeron, et al. 1984;41(3):373-83. PubMed · Publisher · Free full text

Abstract

To study the clinical usefulness of computed tomography (CT) scanning of the thorax in asbestos related pleuropulmonary disease, 127 long term asbestos workers of the mines and mills in the Eastern Townships of Québec were examined. The CT scan was compared with the standard posteroanterior (PA) chest film and the four view films using the ILO grading system for profusion of disease. Six lung areas and six pleural sites were studied. On the basis of the usual diagnostic criteria, 41% of the workers had asbestosis. For profusion of parenchymal disease, there was an excellent correlation (r = 0.96, p less than 0.001) between PA and four view films and the latter did not significantly increase the total profusion score; the CT scan correlated less well with the PA film (r = 0.79, p less than 0.01) and the scatter of the data was larger. In 10 of the 53 (19%) workers with asbestosis the pulmonary lesions were not recognised by CT scan. For profusion of pleural plaques, there was an excellent correlation (p = 0.91, p less than 0.001) between PA and four view films; scores were identical in 73%, higher for PA in 7%, and higher for four view films in 19%. CT scan scores, however, were identical with PA films in 31%, higher for CT scan in 13% (owing to higher scores on lateral pleural sites), and lower for CT scan in 56% (owing to lower scores at diaphragm and costophrenic angle sites). Pleural calcifications were identified in 24 workers for a total of 40 sites; 13 as possible, 31% identified by two modes, and 27 as definite. Of the latter, 14 were seen only on CT scan. In the workers with rigid pressure volume curve of the lung and increased Gallium-67 lung uptake only, CT scan total scores were not significantly higher than in those without these markers of early interstitial lung disease (5 +/- 1 v 4 +/- 1, p less than 0.05). Thus the four view films and CT scan appear to be useful mainly in the assessment of pleural disease. The four view film identifies more sites of pleural plaques and the CT scan more pleural calcified plaques.
Radiographic changes in a group of chrysotile miners and millers exposed to low asbestos dust concentrations. S. Cordier, G. Theriault, S. Provencher. 1984;41(3):384-8. PubMed · Publisher · Free full text

Abstract

Radiographic changes in 342 Quebec asbestos miners exposed to low levels of asbestos dust for an average period of 20 years were studied. Their estimated cumulative exposure ranged from 7 fibres per cubic centimeter X years (f-y/cc) to 300 f-y/cc. Of these workers, 2.1% showed a small opacity score of 1/0 or more and 2.7% showed pleural changes. No linear relationship could be established between small opacity score and any index of exposure to asbestos. Pleural changes were related to age. A referent group of office workers within the same mining industry showed a prevalence of 2.1% (1/48) for small irregular opacities 1/0 or more, and for pleural changes.
An overload hypothesis for pulmonary clearance of UICC amosite fibres inhaled by rats. R.E. Bolton, J.H. Vincent, A.D. Jones, et al. 1983;40(3):264-72. PubMed · Publisher · Free full text

Abstract

Two types of experiments were carried out to examine the effects of deposition and clearance on the accumulation in the lungs of rats of inhaled fibres of UICC amosite. In the first experiment the mass lung burdens of the dust in question were measured as a function of the time at which animals were killed after the cessation of the six week exposure period, and in the second the masses were measured for rats removed from exposure and killed at intervals during the exposure period itself. The experimental conditions were chosen to complement those of earlier work. Taken together with the results of that earlier work, the new results provide the basis for a simple mathematical model of the kinetics of deposition and clearance which appears to account for the major observed trends. Most significantly, there is strong evidence for an overload of clearance at high lung burdens (exceeding about 1500 micrograms/rat), in which a breakdown occurs of the intermediate rate clearance mechanisms (time constants of the order of 12 days). This hypothesis is supported for inhaled asbestos dust, quartz dust, and diesel fume by results obtained elsewhere. Biological explanations for the clearance overload hypothesis are at present speculative, involving discussion of the role of the macrophage in pulmonary clearance. It is believed that the clearance overload hypothesis could have possible consequences for people occupationally exposed to airborne dusts.
Asbestos-related mesothelioma: factors discriminating between pleural and peritoneal sites. K. Browne, W.J. Smither. 1983;40(2):145-52. PubMed · Publisher · Free full text

Abstract

Up to the end of 1980, 144 confirmed cases of mesothelioma were identified among employees of an organisation using asbestos in manufacturing and insulation. The primary site was peritoneal in 74 cases, pleural in 66, and undetermined in four. All employees had been exposed to amphibole asbestos, and evidence from different factories confirmed the predominant role of crocidolite in the production of mesothelioma. The ratio of pleural to peritoneal sites showed a continuous change when related to the year of first exposure, varying from 5:1 pleural to peritoneal before 1921 to 1:3 after 1950. The strong temporal relationship appeared to reflect progressive dust suppression, including the non-fibrous dusts present in insulation materials and perhaps also the degree to which the fibres had been opened. Other predisposing factors were related to the degree of individual exposure, the peritoneal site being associated preferentially with longer and heavier exposures.
Distribution and characteristics of amphibole asbestos fibres, measured with the light microscope, in the left lung of an insulation worker. A. Morgan, A. Holmes. 1983;40(1):45-50. PubMed · Publisher · Free full text

Abstract

Concentrations of uncoated and coated amphibole fibres were measured postmortem in samples taken from the periphery of both upper and lower lobes of the left lung of an insulation worker. Similar measurements were made on a more limited range of samples from elsewhere in the lung and on a hilar lymph node. The mean concentration of uncoated fibres in the upper lobe was twice that in the lower. Significant differences were observed in the mean concentration of uncoated fibres in different regions of the periphery, the diaphragmatic region having the lowest value. Variations in the concentrations of both uncoated and coated fibres in the costal region of the lower lobe may have been related to the effect of rib structures on ventilation. Concentrations of fibrous and non-fibrous dust were well correlated in the peripheral samples. The length distributions of uncoated and coated fibres were also measured and differences detected in fibres from the various regions of the lung. This work emphasises the care required in sampling lung tissue in order to obtain representative material for the determination of fibre concentration.
Dust exposure and mortality in an American chrysotile textile plant. A.D. McDonald, J.S. Fry, A.J. Woolley, et al. 1983;40(4):361-7. PubMed · Publisher · Free full text

Abstract

Three parallel cohort studies of asbestos factory workers were undertaken to investigate the effects of mineral fibre type and industrial process on malignant mesothelioma, respiratory cancer, and asbestosis. This report describes the mortality of a cohort of 2543 men, defined as all those employed for at least a month from 1938 to 1958 in a textile plant in South Carolina in which chrysotile was the only type of asbestos used. Of these, 863 men (34%) had died before 31 December 1977, one from malignant mesothelioma. Twenty one deaths were ascribed to asbestosis and 66 to cancer of the lung. Compared with the number expected from South Carolina, there was an excess of 30 deaths from respiratory cancer (ICD 160-164) in men 20 or more years after first employment (SMR 199.5). In men employed five years or more, no SMRs for this category rose above 300. Individual exposures were estimated (in mpcf X years) from recorded environmental measurements. Life table analyses and "log-rank" (case-control) analyses both showed a steep linear exposure-response that was some 50-fold greater at similar accumulated dust exposures than in Canadian chrysotile mining and milling. These findings agree closely with those from another study in this plant and confirm that mesothelioma is rarely associated with chrysotile exposure. Cigarette smoking habits did not greatly differ between the textile workers and the Canadian miners and millers. The far greater risk of lung cancer in the textile industry, if not attributable to other identified cocarcinogens, may be related to major differences in the size distribution of fibres in the submicroscopic range which are not detected by the usual fibre or particle counting procedures.
Dust exposure and mortality in an American factory using chrysotile, amosite, and crocidolite in mainly textile manufacture. A.D. McDonald, J.S. Fry, A.J. Woolley, et al. 1983;40(4):368-74. PubMed · Publisher · Free full text

Abstract

This report describes the second in a series of three parallel cohort studies of asbestos factories in South Carolina, Pennsylvania, and Connecticut to assess the effects of mineral fibre type and industrial process on mortality from malignant mesothelioma, respiratory cancer, and asbestosis. In the present plant (in Pennsylvania) mainly chrysotile, with some amosite and a small amount of crocidolite, were used primarily in textile manufacture. Of a cohort of 4137 men comprising all those employed 1938-59 for at least a month, 97% were traced. By the end of 1974, 1400 (35%) had died, 74 from asbestosis and 70 from lung cancer. Mesothelioma was mentioned on the certificate in 14 deaths mostly coded to other causes. All these deaths occurred after 1959, and there were indications that additional cases of mesothelioma may have gone unrecognised, especially before that date. The exposure for each man was estimated in terms of duration and dust concentration in millions of dust particles per cubic foot (mpcf) from available measurements. Analyses were made both by life table and case referent methods. The standardised mortality ratio for respiratory cancer for the whole cohort was 105.0, but the risk rose linearly from 66.9 for men with less than 10 mpcf.y to 416.1 for those with 80 mpcf.y or more. Lines fitted to relative risks derived from SMRs in this and the textile plant studied in South Carolina were almost identical in slope. This was confirmed by case referent analysis. These findings support the conclusion from the South Carolina study that the risk of lung cancer in textile processing is very much greater than in chrysotile production and probably than in the friction products industry. The much greater risk of mesothelioma from exposure to processes in which even quite small quantities of amphiboles were used was also confirmed.
Environmental history of a factory producing friction material. J.W. Skidmore, B.L. Dufficy. 1983;40(1):8-12. PubMed · Publisher · Free full text

Abstract

The fibre concentrations generated during the production of friction materials, incorporating asbestos, over the past 60 years have been studied to provide cumulative dust exposure data for a mortality study of the work-force. Chrysotile has been used almost exclusively during this period. The measurements made routinely by the factory staff provided information from 1950 onwards; concentrations for earlier years were derived from simulation studies using original materials, machines, and methods. These have shown that while high concentrations prevailed in the earliest years dust suppression measures initiated in 1931, and other factors, reduced the time-weighted average concentrations to moderate levels. There were two four-year periods when the production of brake blocks incorporating crocidolite occupied a well-defined area of the factory. The simulation of this production was not permissible, but the employees concerned could be identified.
Fibre type and concentration in the lungs of workers in an asbestos cement factory. B. Gylseth, G. Mowé, A. Wannag. 1983;40(4):375-9. PubMed · Publisher · Free full text

Abstract

The predominant asbestos fibre type used in the production of asbestos cement is chrysotile. The use of asbestos in relation to fibre type in a Norwegian asbestos cement plant during 1942-80 was 91.7% chrysotile, 3.1% amosite, 4.1% crocidolite, and 1.1% anthophyllite respectively. Electron microscopy and x ray microanalysis of lung tissue samples of asbestos cement workers who had died of malignant pleural mesothelioma or bronchogenic carcinoma showed a completely inverse ratio with regard to fibre type. The percentage of chrysotile asbestos in lung tissue varied between 0% and 9% whereas the corresponding numbers for the amphiboles were 76% and 99%. These differences are discussed with respect to the behaviour of different fibre types in the human body and to the occurrence of malignant mesothelioma in this asbestos cement factory.
Mortality among long-term employees of an Ontario asbestos-cement factory. M.M. Finkelstein. 1983;40(2):138-44. PubMed · Publisher · Free full text

Abstract

Mortality was studied among a group of 328 employees of an Ontario asbestos-cement factory who had been hired before 1960 and who had been employed for a minimum of nine years. The group of 87 men who had worked in the rock wool/fibre glass operations, or who had been otherwise minimally exposed to asbestos, had mortality rates similar to those of the general Ontario population, while the group of asbestos-exposed employees had all-cause mortality rates double those of the Ontario population, mortality rates due to malignancies five times higher than expected, and deaths attributed to lung cancer eight times more frequent than expected. According to the best evidence available, 10 of 58 deaths among the production workers were due to malignant mesothelioma and 20 to lung cancer. The men dying of mesothelioma were younger than the men dying of lung cancer with mean ages at death of 51 and 64 years respectively. An exposure model was constructed on the basis of the available air sampling data, and individual exposure histories were calculated. These exposure histories were used to investigate the exposure-response relationships for asbestos-associated malignancies.
Mortality of workers manufacturing friction materials using asbestos. G. Berry, M.L. Newhouse. 1983;40(1):1-7. PubMed · Publisher · Free full text

Abstract

A mortality (1942-80) study was carried out on 13460 workers of a factory producing friction materials. The only type of asbestos used was chrysotile, except during two well-defined periods before 1945 when crocidolite was used, and over 99% of the population was traced. Compared with national death rates there were no detectable excesses of deaths due to lung cancer, gastrointestinal cancer, or other cancers; 11 deaths were due to pleural mesothelioma. A case-control study was carried out on deaths due to mesothelioma; this showed that eight workers had been exposed to crocidolite and another was possibly exposed intermittently to crocidolite. The other two had been employed for most of their working lives outside the factory, and their mesotheliomas could not be definitely attributed to exposure to chrysotile. Limiting the study to cases and controls who had exposure to 5 fibres/ml of chrysotile asbestos it was found that five of the six cases compared with two of the 10 controls had also been exposed to crocidolite. The probability (1:36) of this occurring were there no association with crocidolite is most unlikely. A case-control study was also carried out on deaths due to lung cancer and gastrointestinal cancer to investigate the dose-response relationships between these tumours and exposure to chrysotile. Measured and estimated fibre concentrations were available for the different jobs over the period of the study. No dose-response relationships were observed, but the exposures were low with only 5% of men accumulating 100 fibre-years/ml. The experience at this factory over a 40-year period showed that chrysotile asbestos was processed with no detectable excess mortality.
Size and shape of airborne asbestos fibres in mines and mills. C.Y. Hwang. 1983;40(3):273-9. PubMed · Publisher · Free full text

Abstract

There is increasing evidence that fibre size and shape play an important part in the production of health effects related to asbestos. The dimensions of airborne fibres collected at various stages of fibre processing in three mines and six mills producing three types of asbestos were measured using phase contrast light microscopy and transmission electron microscopy. Airborne fibres of different asbestos types had appreciably different size and shape distributions. For a given asbestos type, fibres collected at different stages of processing differed in their size distributions but the differences were considerably less than between fibre types. Most of the airborne fibres to which miners and millers were exposed were short and thin and thus respirable. The physical properties which best differentiated crocidolite fibres from other types of asbestos and which had higher values determined for crocidolite fibres than those obtained for the other types, were median aspect ratio and the proportion of long thin fibres--that is, fibres less than or equal to 0.2 micron in diameter and greater than 5 micron in length as the percentage of total fibres. The median true diameter of amosite fibres was about four and three times higher than the median true diameters of chrysotile and crocidolite fibers respectively. The median true length of amosite fibres was more than four and two times higher than the median true lengths of chrysotile and crocidolite fibres respectively. The observed differences in size and shape of airborne fibres have important implications for the setting of work environmental standards and in explaining differences in health risks associated with different types of fibre.
Tobacco consumption and asbestos exposure in patients with lung cancer: a three year prospective study. G. Hillerdal, E. Karlén, T. Aberg. 1983;40(4):380-3. PubMed · Publisher · Free full text

Abstract

During the three years 1979-81, all patients with bronchial carcinoma of World Health Organisation types I to IV were given a questionnaire to determine occupation, smoking habits, and exposure to asbestos. Chest x rays were screened for the presence of pleural plaques. Of the men, 96.2% were current or ex-smokers, as were 71% of the women. In those who had never smoked 70% had an adenocarcinoma. In smokers the risk of getting other types was greater, but the risk of getting an adenocarcinoma was also considerably increased compared with the normal population. Of the men, 35.8% were occupationally exposed to asbestos and 15.6% were carriers of radiological plaques, a frequency five to six times greater than expected. Practically all asbestos exposed patients with lung tumours were smokers or ex-smokers and their total tobacco consumption was as high as that of non-exposed patients. The average latency from first exposure to asbestos to diagnosis of the lung tumour was 37 years. Even if strict regulations are warranted for the use of asbestos, this cannot prevent future asbestos cancers resulting from exposure that has already occurred. Elimination of smoking seems the only way to reduce such tumours.
Analysis of fibres in human lung tissue. B. Gylseth, R.H. Baunan, L. Overaae. 1982;39(2):191-5. PubMed · Publisher · Free full text

Abstract

Standard UICC crocidolite fibres and fibres extracted from occupationally exposed human lung tissue have been analysed by scanninng electron microscopy after different preparation procedures. A significant fibre loss has been shown due to the adhesion of fibres to the breakers. Fibres are also discarded during the washing and extraction of the lung tissue samples. The recovery was found to be 30 to 40% both for UICC standard specimens and for lung tissue samples.
Asbestos bodies in the lung: Southampton (UK) and Wellington (New Zealand). R.H. Steele, K.J. Thomson. 1982;39(4):349-54. PubMed · Publisher · Free full text

Abstract

Two series of surgically removed and unselected necropsy lungs were examined for asbestos bodies. In the series from Southampton (UK) 30-mu sections were used and in the Wellington (New Zealand) series a modified Gold's digestion method was used for all cases, together with 30-mu sections for some. A further series of Southampton lungs was assessed by Gold's method six years after the initial study. The 30-mu section technique found asbestos bodies in 13% of Southampton men and none in women: the corresponding Wellington figures were 8% for men and nil for women. In Wellington the more sensitive digestion method found asbestos bodies in 78% of men and 63% of women. In Southampton the investigation by Gold's method found asbestos bodies in 83% of men and 74% of women. No statistically significant association was found between the number of asbestos bodies and the various types of lung carcinoma. The prevalence of asbestos in lungs removed between 1956 and 1965 did not differ significantly from its prevalence in those removed in the late 1970's. There was no significant increase in asbestos after the age of 20.
Comparison of independent randomised reading of radiographs with direct progression scoring for assessing change in asbestos-related pulmonary and pleural lesions. G.H. McMillan, C.E. Rossiter, R. Deacon. 1982;39(1):60-1. PubMed · Publisher · Free full text

Abstract

Direct scoring of progression of pleural and parenchymal lesions was compared with change assessed by independent readings to the ILO classification among 155 men from HM Dockyard, Devonport, followed-up for 10 years. For pleural calcification the two methods agreed closely, whereas direct scoring yielded relatively too little progression of small opacities and too much progression of pleural thickening. The choice of method for assessing progression should depend on objectives.
Concentrations and characteristics of amphibole fibres in the lungs of workers exposed to crocidolite in the British gas-mask factories, and elsewhere, during the second world war. A. Morgan, A. Holmes. 1982;39(1):62-9. PubMed · Publisher · Free full text

Abstract

Concentrations and length distributions of uncoated and coated amphibole fibres in the lungs of 27 workers at the Leyland, Nottingham, and Blackburn gas-mask factories were measured after death with the light microscope using the membrane filter technique. Measurements were also made on a worker exposed to crocidolite at the Chemical Defence Experimental Establishment, Porton, and on three miners from the Wittenoom mine in Western Australia where the crocidolite used in the manufacture of military respirators is reputed to have originated. In selected cases, fibre concentrations and dimensions were also measured with the electron microscope. All but two subjects died with a mesothelial tumour. Fibre concentrations ranged from 7 x 10(4) to almost 10(9) fibres/g dry weight. There appeared to be no relation between latent period and fibre concentration. The significance of the wide range of fibre concentrations which was associated with the development of mesothelial tumours is discussed and also the relation between the relative frequency and dimensions of uncoated and coated fibres.
Development of radiological and clinical evidence of parenchymal fibrosis in men with non-malignant asbestos-related pleural lesions. G.H. McMillan, C.E. Rossiter. 1982;39(1):54-9. PubMed · Publisher · Free full text

Abstract

After assessment of radiographs taken in 1966, 201 men employed at HM Dockyard, Devonport, were judged to have pleural abnormalities due to exposure to asbestos but to be free from small opacities (ILO U/C 1971 category 1/1 or more), mesothelioma, or bronchial carcinoma. By 1976, 32 of these men had died. Of the survivors, 155 were re-examined to determine the attack rates of parenchymal fibrosis or malignant disease, or both. In 1976, 16 (10.3%) of the survivors had radiographs showing small opacities of category 1/1 or more. When additional clinical criteria had to be satisfied before a diagnosis of parenchymal fibrosis was made the attack rate in the survivors was 4.5%. These attack rates were substantially higher than those observed in a sample of men with no initial pleural abnormality but were unrelated to age, smoking habit, occupation, duration of exposure to asbestos, or type of pleural abnormality. The number of cases of malignant disease was too small to allow any reliable conclusions.
Evaluation of respiratory effects in miners and millers exposed to talc free of asbestos and silica. D.H. Wegman, J.M. Peters, M.G. Boundy, et al. 1982;39(3):233-8. PubMed · Publisher · Free full text

Abstract

Miners and millers of talc ore, free from asbestos and silica, were examined for respiratory effects. A study of 116 subjects included the modified British Medical Research Council respiratory symptom questionnaire, simple spirometry, chest radiography, and limited examination of the chest. A one-year follow-up evaluation was performed on 103 subjects. Of the 12 subjects whose chest radiographs showed small round or irregular opacities (perfusion 1/0 or greater), five had never smoked cigarettes. Pulmonary function values at the time of the initial study were less than predicted and the rates of loss of FEV1 and FVC greater than expected. These differences were in part attributed to cigarette smoking but were greater than predicted from that source alone. There was evidence of an exposure effect after adjusting for cigarette smoking and we conclude that these workers have been affected by their exposures. No clear interaction between smoking and exposure could be identified. Populations such as this will need to be studied for longer periods to determine what current dust levels are safe.
Further follow-up study of workers from an asbestos cement factory. H.F. Thomas, I.T. Benjamin, P.C. Elwood, et al. 1982;39(3):273-6. PubMed · Publisher · Free full text

Abstract

A further follow-up traced 1970 workers employed at an asbestos cement factory for at least six months between 1936 and 1977. At the beginning of this period some crocidolite was used in the factory but by the end of 1936 chrysotile had become the only type of asbestos in use. Only 378 women were employed during the period concerned, and of the 30 who had died, none had a cause of death that is generally associated with exposure to asbestos. The mortality experience of the men was examined separately for all workers, all workers alive after 15 or more years after first exposure, and a smaller group of workers who were employed in 1935-6 and may have been exposed to crocidolite. In none of the three groups was there an appreciably raised standardised mortality ratio (SMR) for the causes of death investigated. These were: all causes, all neoplasms, cancers of the lung and pleura, and cancers of the gastrointestinal tract. An excess of lung cancers noted in the first follow-up study in 1964 was not found in this study. Two pleural mesotheliomas were identified but in both cases the men had worked at the factory before 1936 and therefore had been exposed to crocidolite. No cancers of the larynx were found.
Lung function and radiographic change in chrysotile workers in Swaziland. M. McDermott, M.M. Bevan, P.C. Elmes, et al. 1982;39(4):338-43. PubMed · Publisher · Free full text

Abstract

The effect on lung function and radiographic indices of exposure to chrysotile asbestos was investigated by cross-sectional studies in two groups of men at Havelock Mine, Swaziland. The first group consisted of 214 employees and ex-employees, mean age 52, who had been employed for at least 10 years, and whose dust exposure ranged from minimal for surface workers to very heavy for those in the grading and bagging sections of the mill. In this group 29% had category 1 or more simple pneumoconiosis and 4.5% category 2 or more. For surface and mine workers, the estimated annual deterioration in FEV1 and FVC and the increase in category of pneumoconiosis was similar to that due to age alone, while the heaviest exposure almost doubled the decline in lung function and trebled the rate of progression of pneumoconiosis. The second group consisted of 224 men, mean age 33, all currently working in the mill and having been employed there for at least a year. In this group 30% had category 1 or more simple pneumoconiosis, and 2.7% category 2. Exposure in the dustiest sections of the mill more than doubled the estimated annual decline in lung function and doubled the rate of progression of pneumoconiosis.
Mortality of female gas mask assemblers. B.K. Wignall, A.J. Fox. 1982;39(1):34-8. PubMed · Publisher · Free full text

Abstract

A 30-year follow-up study of the mortality of 500 women employed in manufacturing gas masks during the second world war showed a pronounced excess of deaths from mesothelioma and lung cancer. Although these women were subject only to short periods of exposure, greater excesses were found for those exposed for between one and five years than for those exposed for under one year. Even in the latter group, however, five deaths from lung cancer and four deaths from mesothelioma were recorded compared with 1.5 deaths and 0.1 deaths expected (p approximately equal to 0.02). An excess of deaths from cancer of the ovary was also found, and this appeared to be related to exposure to asbestos.
Mortality of two groups of women who manufactured gas masks from chrysotile and crocidolite asbestos: a 40-year follow-up. E.D. Acheson, M.J. Gardner, E.C. Pippard, et al. 1982;39(4):344-8. PubMed · Publisher · Free full text

Abstract

ABSTRACT Two groups of women were exposed to asbestos while manufacturing gas masks in Lancashire before and during the second world war. One group (in Blackburn) is believed to have been concerned almost exclusively with the manufacture of civilian respirators (containing chrysotile) while the other (in Leyland) made respirators for the armed Forces (containing crocidolite) and a much smaller number of civilian respirators. Excess mortality ascribed to lung cancer and ovarian cancer were found at the second factory (statistically significant at the 1% level) but not at the first. Mesothelioma was mentioned on the death certificates of five women who had worked in Leyland and one woman in Blackburn.
On the defensive action of glutamate against the cytotoxicity and fibrogenicity of quartz dust. K.I. Morosova, G.V. Aronova, B.A. Katsnelson, et al. 1982;39(3):244-52. PubMed · Publisher · Free full text

Abstract

The cytotoxic action of quartz (DQ12) particles on cultures of rat peritoneal macrophages, as estimated by the inhibition of the TTC-reductase activity, is considerably reduced by preincubation with glutamic acid and by adding sodium glutamate (15 mg/ml) to the drinking water of the rats donating the macrophages. This increase in macrophage resistance under the influence of glutamate is the most probable cause of the delay in the development of silicotic fibrosis shown in several experiments on rats intratracheally injected with quartz and then treated by prolonged administration of glutamate. This effect is probably connected with the influence of glutamate on the stability of the macrophage membranes, which can in its turn be explained by different mechanisms, including the influence on the synthesis and phosphorylation of adenosine nucleotides. Such an influence was shown in rats receiving glutamate by the change of the ATP/ADP ratio in macrophages, but not in erythrocytes. The resistance of rat erythrocytes to the haemolytic action of quartz is also not influenced by the action of glutamate neither in vitro nor in vivo. Such differences in the influences of glutamate on two types of cells, equally susceptible to quartz cytotoxicity but considerably differing in the character of energy metabolism, is an indirect proof of the role of the latter in the realisation of the anticytotoxic, and thereby antifibrogenic, effect of glutamate.
A technique to prepare asbestos air samples for light and electron microscopy. T.W. Pang, A.E. Robinson. 1981;38(4):389-93. PubMed · Publisher · Free full text

Abstract

The direct transfer technique used in preparing waterborne asbestos for analysis by transmission electron microscopy is also suitable for preparing airborne asbestos collected on polycarbonate filters for light microscopy, scanning, and transmission electron microscopy. The same area and even the same fibre may be examined by the three microscopic methods and individual fibres identified by optical and electron-optical techniques and by x-ray microanalysis.
Mortality of workers certified by pneumoconiosis medical panels as having asbestosis. G. Berry. 1981;38(2):130-7. PubMed · Publisher · Free full text

Abstract

A mortality study has been carried out at the London, Cardiff, or Swansea Pneumoconiosis Medical Panels between 1952 and 1976 on people certified as suffering from asbestosis. The main analysis was of 665 men, 283 of whom had died. Of the deaths, 39% were from lung cancer, 9% mesothelioma, and 20% asbestosis. The observed mortality was compared with expectation based on the death rates for England and Wales. For all causes the observed number of deaths was 2.6 times expectation and for lung cancer 9.1 times expectation. After 10 years from first certification half of the men had died compared with an expectation of one in four. The excess death rates were apparent in the first year after certification and were still operating after 10 years on those who survived until then. The main factor influencing the mortality was the clinical state of the men at the time of certification, as indicated by the percentage disability awarded; the excess lung cancer rate and the mesothelioma and asbestosis rates all increased with percentage disability. Those awarded only 10% or 20% benefit were still at risk from all the three asbestos-related causes. For a man certified at age 55 it was estimated that his life expectation would be reduced by 3, 5, 8, or 12 years according to whether his rate of disablement benefit was 10%, 20%, 30% or 40% , or 50% or more respectively.
Non-invasive magnetopneumographic determination of lung dust loads in steel arc welders. A.P. Freedman, S.E. Robinson, K. O'Leary, et al. 1981;38(4):384-8. PubMed · Publisher · Free full text

Abstract

Magnetopneumography was used to measure non-invasively the concentration of the ferrimagnetic fraction of retained welding fume in the thoraces of steel arc welders. This was done by measuring the remanent magnetic fields due to ferrimagnetic particles. The 11 welders studied had concentrations of thoracic ferrimagnetic mineral several orders of magnitude greater than three machinists, 16 former asbestos insulators and 24 control subjects. These concentrations correlated well with total years welding (p less than 0.01) and radiographic evidence of small rounded densities (p less than 0.05), but not with smoking history. There was a higher concentration of ferrimagnetic mineral over the hilar regions. Magnetopneumography offers a non-invasive indicator of the accumulation of welding fume in the thorax.
Relative importance of cigarette smoking in occupational lung disease. P.C. Elmes. 1981;38(1):1-13. PubMed · Publisher · Free full text

Abstract

Since 1900 respiratory disease has remained a constant serious cause of chronic ill health and premature death in Britain. The falling importance of tuberculosis and pneumonia has been off-set by the rise in lung cancer. Bronchitis morbidity and mortality have fallen only slightly since 1935. To produce any real improvement in the future existing information as to cause must be studied. The relative contribution of occupational exposure is compared with the importance of cigarette smoking. Relevant information is scanty and has been produced to emphasise the existence of occupational diseases rather than assess their importance to the community as whole. In Britain the evidence is that within the coal mining and iron and steel industries conditions are now such that dust exposure contributes little to the morbidity or mortality compared with the workers' smoking habits. Similar results have been shown by a cross-sectional survey of many dusty occupations in Western Germany. Only in the disappearing Welsh slate industry has dust disease been at least as important as smoking. Until the current regulations were introduced conditions existed among asbestos workers such that the combined effect of cigarette smoking and dust exposure led to a loss of life expectation of over 10 years in moderate smokers. Since the new regulations were introduced the risk for asbestos workers should approximate to that for other industrial workers. While control of occupational exposure to respiratory hazards remains important, a far greater improvement to respiratory health would be produced by controlling tobacco smoking.
Chemical and photoelectron spectrometry analysis of the adsorption of phospholipid model membranes and red blood cell membranes on to chrysotile fibres. M.C. Jaurand, J.H. Thomassin, P. Baillif, et al. 1980;37(2):169-74. PubMed · Publisher · Free full text

Abstract

A study of the interaction of phospholipid model membranes and red blood cell membranes with UICC A chrysotile fibres using chemical analysis and photoelectron spectrometry showed that the interaction agreed with an adsorption of the membranes on to the chrysotile fibres. The photoelectron spectrometry analysis allowed the statement that phospholipid model membranes are adsorbed as bilayer. Chemical analysis showed that for each milligram of chrysotile the amount of phospholipids adsorbed was about 155 microgram and the available surface for phospholipids was about 38 m/g. It was established that entire membranes were adsorbed. A mechanism for the haemolytic capacity of chrysotile is suggested.
Clearance of asbestos bodies from the lung: a personal view. K.J. Arul, P.F. Holt. 1980;37(3):273-7. Case report PubMed · Publisher · Free full text

Abstract

In histological sections asbestos bodies in human lungs may be either transparent, yellow, strongly Perls-positive structures as described in published reports, or opaque, black structures, the ferroprotein coating having been converted into haemosiderin. The transparent asbestos bodies fragment into segments; the black asbestos bodies disintegrate into a mass of haemosiderin granules that accumulate as dense deposits, particularly near to blood vessels. The presence of haemosiderin granules indicates that asbestos bodies have broken down. When a patient has died with a mesothelioma there is little evidence of phagocytic activity in many areas of the lung. When exposure to asbestos ceased many years before a mesothelioma developed there may be few recognisable asbestos bodies remaining in the lung.
Concentrations and dimensions of coated and uncoated asbestos fibres in the human lung. A. Morgan, A. Holmes. 1980;37(1):25-32. PubMed · Publisher · Free full text

Abstract

Concentrations and length distributions of uncoated and coated amphibole-type fibres in samples of human lung taken at necropsy were measured by optical microscopy using the membrane filter technique that enables fibres with diameters down to about 0.2 micron to be detected. The subjects included 10 who died with mesothelial tumours, three with lung cancer, and eight of other causes. Measurements of fibre concentrations are compared with those of other workers. It can be deduced from the length distributions that fibres less than 5 microns long are cleared from the lung more efficiently than longer ones. The clearance of short fibres appears to be inhibited in subjects with asbestosis, however. The length distributions of uncoated and coated fibres were dissimilar. In general, few fibres less than 10 microns in length were coated and few greater than 40 microns in length were uncoated. The probability of a fibre of given length, however, becoming coated varied considerably from subject to subject. Possible reasons for this are discussed.
Dust exposure and mortality in chrysotile mining, 1910-75. J.C. McDonald, F.D. Liddell, G.W. Gibbs, et al. 1980;37(1):11-24. PubMed · Publisher · Free full text

Abstract

We report a further follow-up of a birth cohort of 11 379 workers exposed to chrysotile. The cohort consisted of 10 939 men and 440 women, born 1891-1920, who had worked for at least a month in the mines and mills of Asbestos and Thetford Mines in Quebec. For all subjects, length of service and estimates of accumulated dust exposure were obtained, with a smoking history for the vast majority. Three methods of analysis, two based on the "man-years" methods, the other a "case-and-multiple-controls" approach, gave results consistent with one another and with previous analyses. By the end of 1975, 4463 men and 84 women had died. Among men, the overall excess mortality, 1926-75 was 2% at Asbestos and 10% at Thetford Mines, much the dustier region. The women, mostly employed at Asbestos, had a standardised mortality ratio (SMR) all causes, 1936-75) of 0.90. Analysis of deaths 20 years or more after first employment showed that in men with short service (less than five years) there was no discernible correlation with dust exposure. Among men employed at least 20 years, there were clear excesses in those exposed to the heaviest dust concentrations. Reanalysis in terms of exposure to age 45 showed definite and consistent trends for SMRs for total mortality, for lung cancer, and for pneumoconiosis to be higher the heavier the exposure. The response to increasing dose was effectively linear for lung cancer and for pneumoconiosis. Lung cancer deaths occurred in non-smokers, and showed a greater increase of incidence with increasing exposure than did lung cancer in smokers, but there was insufficient evidence to distinguish between multiplicative and additive risk models. There were no excess deaths from laryngeal cancer, but a clear association with smoking. Ten men and one woman died from pleural mesothelioma. If the only subjects studied had been the 1904 men with at least 20 years' employment in the lower dust concentrations, averaging 6.6 million particles per cubic foot (or about 20 fibres/cc), excess mortality would not have been considered statistically significant, except for pneumoconiosis. The inability of such a large epidemiological survey to detect increased risk at what, today, are considered unacceptable dust concentrations, and the consequent importance of exposure-response models are therefore emphasised.
Effect of smoking on attack rates of pulmonary and pleural lesions related to exposure to asbestos dust. G.H. McMillan, R.J. Pethybridge, G. Sheers. 1980;37(3):268-72. PubMed · Publisher · Free full text

Abstract

In follow-up studies of samples of employees at two of Her Majesty's Dockyards the prevalence of asbestos-related lesions in smokers and ex-smokers was statistically significantly higher than in non-smokers even when differences in age and exposure risk were considered.
Mortality and incidence of tumours among ferrochromium workers. G. Axelsson, R. Rylander, A. Schmidt. 1980;37(2):121-7. PubMed · Publisher · Free full text

Abstract

ABSTRACT An investigation was carried out to determine the cause of death and the incidence of tumours among 1932 workers in a ferrochromium plant in Sweden. The workers had been exposed mainly to metallic and trivalent chromium (Cr3+); hexavalent chromium (Cr6+) was also present in certain working operations. The population was defined as all men employed at the plant for at least one year during 1930-75, and were classified according to their occupation within the industry. The causes of death were initially obtained from parish registers. For deaths occuring between 1951 and 1975, death certificates were collected from the National Central Bureau of Statistics. Data on the incidence of cancer during 1958-75 were obtained from the Swedish National Cancer Registry. Expected death rates and incidence of tumours were calculated, based on the rates for the county in which the factory was situated. The total number of deaths from tumours was less than expected (69 versus 76·7). Five cases of respiratory cancer were found, against an expected 7·2. Among maintenance workers, an increased death rate from all tumours and an increased number of respiratory tumours were found. Two of the latter were mesotheliomas and could be connected with asbestos exposure. No increase was found for respiratory tumours among the heavily exposed workers at the arc-furnaces; one case of mesothelioma was found in this group.
Nature, structure, and properties of asbestos cement dust. J. Baeten, J. Helsen, A. Deruyttere. 1980;37(1):33-41. PubMed · Publisher · Free full text

Abstract

ABSTRACT Total dust samples produced by machining three commercial asbestos-cement products (autoclaved sheet, non-autoclaved sheet, pipe) were examined for their dimensional, surface, and physicochemical characteristics. Microscopic inspection of dust fractions with different settling characteristics in air allowed determination of the simple dimensional features that apply to respirable fibres—that is, the true diameter, length, and aspect ratio and the coil diameter, coil length, and coil aspect ratio. The respirable fraction as a percentage of the total dust varied with the type of machined product: 8·5% for non-autoclaved sheet, 10·5% for autoclaved sheet, and 35% for pipe. Quantitative x-ray diffraction of different granulometric fractions showed that the asbestos content decreases with fraction size (thus the asbestos content will change with distance from the dust source). Electron microscopic examination of fine dust (aerodynamic diameter < 7 μm) showed that only about 10% of the inspected particles were optically virgin. From these observations it has been calculated that the threshold limit value of 2 fibres per cm3 of air corresponds to a total dust concentration of 1·2, 0·6, and 0·1 mg/m3 and to a maximum admissible respirable dust content of 0·1, 0·06, and 0·04 mg/m3 for non-autoclaved sheet, autoclaved sheet, and pipe respectively. The surface of optically virgin fibres may still be contaminated by calcium containing particles, as shown by analytical transmission and scanning electron microscope. Dust from the autoclaved product contains fewer calcium coated fibres. The physicochemical behaviour of dust, as shown by dissolution kinetics and absorption of carcinogens from tobacco smoke, is comparable to the behaviour of cement rather than of pure asbestos. In general, asbestos cement dust differs consistently from pure asbestos. Conclusions, drawn from studies on pure asbestos, cannot be applied as such to asbestos cement dust.
Radiological findings as predictors of mortality in Quebec asbestos workers. F.D. Liddell, J.C. McDonald. 1980;37(3):257-67. PubMed · Publisher · Free full text

Abstract

Two cohorts of chrysotile miners and millers in Quebec were selected to study the extent to which chest radiographs taken while still employed predict mortality. The paper presents mainly findings in much the larger cohort, which consisted of 4559 men (two-thirds past workers) whose latest radiograph had been assessed by one of six experienced readers into what became the UICC/Cincinnati (U/C) classification; by the end of 1975 there had been 1543 deaths in this cohort. The findings were generally confirmed in the other cohort, comprising 988 current male workers, who had been examined in 1967-8 by questionnaires on respiratory symptoms and smoking and by lung function tests, and for whom all six readers had assessed their 1966 radiographs into the U/C classification; 130 men had died by the end of 1975. Men with any radiographic abnormality, heavy dust exposure, or a history of cigarette smoking had relative risks (RRs) of total mortality greater than unity. Death from pneumoconiosis was associated with small parenchymal opacities, usually irregular, of profusion l/l or more, and with heavy dust exposure but not with smoking. Most who died from lung cancer had smoked cigarettes, or had been heavily exposed to dust, or both. Small parenchymal opacities were present in most but not all the excess deaths due to lung cancer. Deaths from other malignant diseases showed no consistent dust or x-ray patterns. RRs of deaths from most other causes were raised for certain radiographic features. Failures in forecasting mortality were primarily due to deaths in which asbestos-related disease was not the primary cause but may have been a contributing factor. The main findings validated the U/C classification convincingly, particulary as the films had been taken as routine and were of modest quality. Despite objective rules for the reading and the fact that all six readers were contributing to the development of the classification, there was inevitably some observer variation. The importance of radiographic technique and the need for careful control of the reading is evident. Our results provide support for the use of the chest radiograph for surveillance of asbestos workers, and for environmental monitoring. Its protective value for individual workers, however, is limited to the extent that radiological progression continues after withdrawal from exposure, and by the carcinogenic risk associated with dust already retained.
Scanning electron microscopy and x-ray microanalysis of mineral deposits in lungs of a patient with pleural mesothelioma. E.M. Ophus, G. Mowé, K.K. Osen, et al. 1980;37(4):375-81. Case report PubMed · Publisher · Free full text

Abstract

Scanning electron microscopy of lung tissue, ashed at low temperature, and obtained from an insulation worker who had died of pleural mesothelioma, showed the presence of numerous inorganic particles and fibres. A regional variation in fibre concentration in different tissue samples was found, and the size distribution of naked fibres and asbestos bodies was determined. By energy dispersive x-ray microanalysis the fibres were identified mainly as amphibole asbestos. This method also showed the presence of particles containing titanium and of fragments of diatom shells. Despite a mean concentration of 33 x 10(6) fibres per gram of dry tissue no significant lung fibrosis was found.

1970s

Asbestosis: a study of dose-response relationships in an asbestos textile factory. G. Berry, J.C. Gilson, S. Holmes, et al. 1979;36(2):98-112. PubMed · Publisher · Free full text

Abstract

ABSTRACT A group of 379 men who had worked at an asbestos textile factory for at least 10 years has been followed up. The prevalence of crepitations, 'possible asbestosis', certified asbestosis, small opacities in the chest radiograph and values of lung function have been related to dust levels. The type of asbestos processed was predominantly chrysotile although a substantial amount of crocidolite had also been used in the past. There was a higher prevalence of crepitations than had been observed previously at the same factory. The presence of crepitations is not a specific effect of asbestos exposure and 'possible asbestosis', a combined judgement of two physicians on whether a man had developed signs which might be attributable to early asbestosis, was preferred. Fifty per cent of men with a diagnosis of possible asbestosis were certified as suffering from asbestosis by the pneumoconiosis Medical Panel within 3-5 yr. The most reliable data relate to men first employed after 1950; 6·6% of men in this group had possible asbestosis after an average length of follow-up of 16 yr and an average exposure to 5 fibre/cm3 where the dust levels were determined by static area samplers. The forced expiratory volume and forced vital capacity declined significantly with exposure, after allowing for age and height, but there was no decline in the total lung capacity. The transfer factor also declined with exposure, but not to a statistically significant extent. The non-smokers and light smokers as a group had less crepitations, asbestosis and small opacities on the chest radiograph than heavier smokers with similar exposure. Combining dust concentrations to form the cumulative dose may not be completely satisfactory, and a family of measures was investigated which allows for elimination of dust from the lungs and includes the cumulative dose as a special case. Because the rate of elimination of dust from the lungs is unknown and cannot be estimated from the data, this approach leads to a wide range of possible interpretations of the data; for example the concentration such that possible asbestosis occurs in no more than 1% of men after 40 years' exposure could be as high as 1·1 fibres/cm3 or may have to be as low as 0·3 fibres/cm3. This range is wide because the data relate to higher dust levels, and a shorter period of follow-up. Until data are available on groups exposed to lower levels it will not be possible to assess the effects of the current standard with any certainty. However, the results of this study show that it is important to continue to reduce dust levels to values as low as possible.
Inhibition by phospholipids of haemolytic action of asbestos. M.C. Jaurand, L. Magne, J. Bignon. 1979;36(2):113-6. PubMed · Publisher · Free full text

Abstract

Haemolysis by asbestos fibres results from an increase in membrane permeability and not from rupture of red blood cells (RBC). The effect of chrysotile asbestos on RBC is at least partly, if not completely, attributable to lipid extraction and adsorption on to the fibres. This was suggested by the hyperbolic relationship between the haemolytic activity of chrysotile and the relative concentration of both chrysotile and RBC. Moreover, it was shown that pre-incubation of chrysotile with lipids, either as RBC membranes or with pure lipids in the form of liposomes, prevents haemolysis.
Mortality of chrysotile asbestos workers at the Balangero Mine, Northern Italy. G.F. Rubino, G. Piolatto, M.L. Newhouse, et al. 1979;36(3):187-94. PubMed · Publisher · Free full text

Abstract

The mortality from 1946 to 1975 of over 900 North Italian chrysotile asbestos workers first employed between 1930 and 1965 has been studied. Nine deaths were certified as attributable to asbestosis, and eleven to lung cancer. One death was attributed to mesothelioma of pleura but this diagnosis was not supported by histological examination. Comparison with the national figures for all Italy did not reveal an excess of deaths from lung cancer but during the last quinquennium of observation, the SMR for lung cancer rose to 206. Simulation experiments enabled a dust index in fibre/years to be attached to each man in the cohort. All but two of the deaths from lung cancer occurred in the higher exposure group. The relative risk of lung cancer in this group was 2.89. The eleven workers who died from lung cancer were all cigarette smokers. A further period of observation is required to monitor the mortality of the surviving workers.
Radiological changes after withdrawal from asbestos exposure. M.R. Becklake, F.D. Liddell, J. Manfreda, et al. 1979;36(1):23-8. PubMed · Publisher · Free full text

Abstract

ABSTRACT A group of 135 ex-employees of the Quebec chrysotile production industry comprising men who were born between 1901 and 1920, who had left the industry between 1950 and 1961, and had been radiographed before leaving, attended in 1972 for a medical examination and further chest radiograph. This report concerns 86 men whose withdrawal film was within 12 months of leaving and who had not been exposed subsequently to asbestos or other fibrogenic dust. Seven separate assessments were made of the paired radiographs, side by side in known temporal order. The assessments were classified as showing 'increse' or 'no change'. In 66 film-pairs from men with two years' employment or longer, at least four assessments were of parenchymal increase in six, of pleural increase in 13, and of both parenchymal and pleural increase in two, total 21 (or 31%). There was similar agreement of no change in 24 pairs (36%), and evidence was equivocal in the remaining 21 pairs. Parenchymal increase was not agreed in any of the 20 film-pairs from men with shorter employment, but pleural increase was seen in four of these men, a proportion similar to that in those exposed longer. We conclude that the parenchymal changes observed after leaving the industry, most of which were 'attacks' rather than 'progression', were attributable to the earlier occupational exposure to chrysotile; there were no important differences in age or smoking habit between those with and without parenchymal change.
Thickening of pulmonary interlobar fissures: exposure-response relationship in crocidolite and amosite miners. A. Solomon, L.M. Irwig, G.K. Sluis-Cremer, et al. 1979;36(3):195-8. PubMed · Publisher · Free full text

Abstract

ABSTRACT In a cross-sectional study of all white and mixed-race men employed at South African crocidolite and amosite mines, data on duration of asbestos exposure and radiological findings were available for 162 men, 94% of the total population. Postero-anterior radiographs were read by three experienced readers. Abnormality was regarded as present if reported by at least two of them. The reading included an assessment of whether interlobar fissures were not visible, were visible but not thickened, or were thickened according to criteria shown in a reference radiograph. Fissures which were visible but not thickened were seen in almost half the men and were not more common in men with longer asbestos exposure. On the other hand, thickened fissures increased in prevalence from about 2% in those who had worked with asbestos for 7 years or less, to 25% in those with more than 15 years' asbestos exposure. Some other asbestos-associated pleural or parenchymal abnormality occurred in 69% of men with thickened fissures. The prevalence of thickened fissures as an isolated abnormality was also related to the duration of asbestos exposure. Because its prevalence is related to duration of exposure, and its recognition is not subject to excessive inter-observer variation, we suggest that thickening of the fissures is a valuable sign in the radiological assessment of workers exposed to asbestos.
UK Naval Dockyards asbestosis study: survey of the sample population aged 50-59 years. C.E. Rossiter, P.G. Harries. 1979;36(4):281-91. PubMed · Publisher · Free full text

Abstract

As part of a general morbidity study of all civilian employees in the four Royal Naval Dockyards, the clinical, radiological and physiological effects of exposure to asbestos in 1200 men aged 50-59 years were studied in detail. The sample included all men on the Register of Asbestos Workers, one in three of those currently in occupations where intermittent exposure to asbestos may occur, and one in 30 of the remainder. The conclusions are mainly in accord with those of the comprehensive morbidity study of all the civilian dockyard workers, and show that smoking played a large part in increasing prevalence rates of radiographic, clinical, and physiological abnormalities in this population. A sub-group of 39 men, who were working as asbestos laggers or sprayers before 1957, was identified. These men showed much more extensive disease than any other sub-group, yet, even so, the smokers were worse than the non-smokers. Of these smokers, 48% had small opacities of category 1/1 or more, 76% reported that they coughed during the day and 53% had crepitations; forced expiratory volume and transfer factor were also markedly reduced in these 21 smokers. Although asbestos exposure had been intermittent for the majority of the population, the prevalences of pleural thickening, small opacities, current respiratory symptoms and crepitations were shown to be related to duration of exposure to asbestos.
Experimental asbestosis: an investigation of functional and pathological disturbances. I. Methods, control animals and exposure conditions. D.M. Hiett. 1978;35(2):129-34. PubMed · Publisher · Free full text

Abstract

The measurement of respiratory function and quantitative assessment of changes in lung morphology are described in a long-term study of asbestos-exposed guinea pigs. Resistance and dynamic compliance of the guinea pig respiratory system were measured non-destructively, and the tidal volume and rate of spontaneous breathing were also determined. A point counting technique was used with histological preparations to quantify morphological changes. In one group of control animals, investigated between 3 and 28 months of age, dynamic compliance and tidal volume tended to increase, but resistance and breathing rate tended to decrease, as the animals matured. In contrast the percentage by volume of various lung components remained constant throughout this period. The animals were exposed to chrysotile and amosite aerosols, both aerosols containing high concentrations of short fibres (less than 5 micrometer) and at least 1000 fibres/ml longer than 5 micrometer. The total fibre concentration during chrysotile exposure was probably at least double that during amosite exposure. A gradient of fibre concentration (less than 5 micrometer) was detected along the exposure chamber, but this gradient was not reflected in the respiratory function of animals exposed at different positions along the chamber. These findings are discussed in relation to possible dose-dependence of the response.
Experimental asbestosis: an investigation of functional and pathological disturbances. II. Results for chrysotile and amosite exposures. D.M. Hiett. 1978;35(2):135-45. PubMed · Publisher · Free full text

Abstract

ABSTRACT Long-term studies of respiratory function and lung morphology were carried out on control groups of guinea pigs and matched groups exposed by inhalation to asbestos dust. Animals were exposed to aerosols of chrysotile or amosite asbestos containing large numbers of short fibres, for either 9 or 18 days. Resistance and dynamic compliance of the guinea pig respiratory system were measured non-destructively, while the point counting technique was applied to the histological preparations. Under these exposure conditions the extent of pathological and functional changes were not related to differences in duration of exposure. Such changes were more marked, however, in animals exposed at eight rather than three months of age. The measurement of dynamic compliance provided the most sensitive assessment of the functional disturbances, which were more extensive following chrysotile exposure. Progressive peribronchiolar fibrosis developed about 40 weeks after chrysotile exposure at eight months of age, but not until about 70 weeks for animals exposed when three months old. No fibrotic reaction was seen during the 70 weeks of the amosite experiments. The relationships between pathological and functional changes throughout these experiments are discussed, and explanations for the apparent differences in fibrogenicity between chrysotile and amosite are suggested. Early detection of asbestosis may be aided by use of lung function tests known to be sensitive to small airways disease.
Significance of fibre length in the clearance of asbestos fibres from the lung. A. Morgan, R.J. Talbot, A. Holmes. 1978;35(2):146-53. PubMed · Publisher · Free full text

Abstract

Rats were exposed by inhalation to radioactive anthophyllite asbestos. Animals were then killed serially over a period of 205 days and the fibre content of the lungs measured radiometrically. The lungs were subjected to selective bronchopulmonary lavage and the mean fibre content determined of free cells recovered from the alveolar spaces. The length distributions of fibres recovered from the lungs by lavage, and of those remaining in the lungs following lavage, were measured. Short (less than 5 micrometer) fibres are cleared from the lung via the conducting airways more efficiently than longer fibres and fibres exceeding 50 micrometer in length are not removed from the lungs by this route. Although fibres of about 200 micrometer in length were present in all the lungs examined, the longest which could be recovered by lavage, once fibre deposited in the airways had been cleared, was only about 100 micrometer decreasing to 60-70 micrometer after 205 days. It is suggested that long fibres are more liable than short to penetrate the alveolar wall as they tend to bridge the alveolar ducts and alveoli.
TruCutR needle biopsy in asbestosis and silicosis: correlation of histological changes with radiographic changes and pulmonary function in 41 patients. P. Tukiainen, E. Taskinen, O. Korhola, et al. 1978;35(4):292-304. PubMed · Publisher · Free full text

Abstract

A percutaneous needle biopsy was performed with a TruCut needle on 41 patients with suspected pneumoconiosis. Patients selected for biopsy tended to have brief or unusual dust exposure, as well as questionable radiographic opacities. Sixteen had been exposed to asbestos, 13 to silica and 12 to mixed dust containing quartz, coal, iron, asbestos and talc. All patients in the asbestos group and most in the other two groups had a reduced transfer factor. Most patients in the asbestos group and about 25% of the other patients had restrictive ventilatory impairment. Chest radiographs were assessed according to standard films of the ILO U/C International Classification (International Labour Office, 1972). In 25 patients radiographic opacities were absent or acanty (categories 0--1/1). The dominant radiographic feature of many patients exposed to asbestos was a ground-glass appearance or a bilateral elevation of the diaphragm, or both, features difficult to assess according to the ILO U/C scheme. Most histological changes were those usually seen in pneumoconiosis. However, in only two patients with silicosis were silicotic nodules detected. The specimens of seven patients showed a granulomatous inflammation. The severity of alveolar wall involvement correlated well with the transfer factor value but poorly with radiographic changes. The profusion of radiographic opacities also correlated poorly with functional impairment. As a diagnostic tool the needle biopsy was valuable in asbestosis and slightly less so in mixed-dust fibrosis. The biopsy specimens showed changes compatible with asbestosis in 75% of the suspected cases and in 86% of those in which asbestosis was the final diagnosis. In the mixed-dust group pneumoconiosis was confirmed in 67% and 80%, respectively. In the diagnosis of silicosis an open biopsy is probably more reliable than a percutaneous one, particularly if radiographic changes are minimal. Histological changes in the needle biopsy specimen were compatible with silicosis in only 36% of the suspected cases and in 63% of those in which the final diagnosis was silicosis.
UK Naval Dockyards Asbestosis Study: radiological methods in the surveillance of workers exposed to asbestos. G. Sheers, C.E. Rossiter, J.C. Gilson, et al. 1978;35(3):195-203. PubMed · Publisher · Free full text

Abstract

ABSTRACT In a survey of the effects of exposure to asbestos in the UK Naval Dockyards, small- and large-film chest radiographs of 674 men have been examined. These films have been read under survey conditions by two readers using a simple screening classification, and also in a controlled trial by five readers using the full ILO U/C classification. Comparison between the reading methods showed a deficiency, independent of the size of film, of at least 30% in the detection of asbestos-related radiographic abnormalities when the screening classification was used. For adequate diagnostic sensitivity the ILO U/C classification appears to be essential. There was a deficiency of 43% in significant abnormalities observed by a majority of readers in the small films when directly compared with large film readings. This deficiency could be reduced to 7% by using readings of the small films at any level of abnormality by any of the five readers. When the ILO U/C readings were related to the clinical diagnoses, the only abnormality missed was a small pleural plaque. Films with previously agreed coding were inserted at intervals during the reading trial and helped to maintain the consistency of reading. Right oblique views were taken for 1884 men, in addition to the full-sized postero-anterior view, but the contribution provided by this view proved insufficient to justify its use in large surveys. The cost of a survey when small films are used as a screening method is reduced to between one-third and one-half of the cost when large films are used, assuming that the abnormality rate is not more than 5%. However, this cost advantage for small films is likely to be overtaken by the development of automatic large-film units. The radiation dose when small films are used is increased by a factor of about 20, but is within the prescribed safety level. It is concluded that at least three readers should be involved, using the full ILO U/C classification. Small films may be of particular use in a large-scale survey, in which the abnormality rate is expected to be low, and which might otherwise be too expensive. A sensitive reading method and a high standard of film quality are essential factors in the use of this technique.
200 kV xeroradiography in occupational exposure to silica and asbestos. R.G. Thomas, G.K. Sluis-Cremer. 1977;34(4):281-90. PubMed · Publisher · Free full text

Abstract

Some details of the physics of xeroradiography, and the bearing these have on films of the lung obtained by this technique, are discussed. In experiments designed to obtain useful films with a minimum of radiation exposure it was found that an exposure range of 10-30 mas at 200 kV at 1.35 m (4 1/2 ft) without a grid or air gap gave very satisfactory results. The positive model of development was considered to give more information than the negative mode. One hundred and fourteen miners who had been exposed to silica dust, asbestos dusts or both, were examined by this technique. The xeroradiographs were compared with silver halide films taken at 200 kV. The xeroradiographs were considered to be superior in several respects, especially in the delineation of vascular shadows, normal and abnormal linear opacities. Linear opacities in asbestos-exposed subjects were better shown on the xeroradiographs and were occasionally seen on these films when the 200 kV conventional film was entirely normal. Small rounded opacities of silicosis were very poorly shown on the xeroradiographs. Pleural thickening and pleural plaques may be very well demonstrated.
A mortality study among workers in an English asbestos factory. J. Peto, R. Doll, S.V. Howard, et al. 1977;34(3):169-73. PubMed · Publisher · Free full text

Abstract

The previous report on this cohort study of workers in an asbestos textile factory (Knox et al., 1968) showed little evidence of increased mortality among workers who had entered the factory after the implementation in 1932 of the first Asbestos Industry Regulation (1931) but observed that no firm conclusions could be drawn, as little carcinogenic effect would be expected for 20 years after first exposure. A further 8 1/2 years of follow-up has revealed some asbestos-related disease in this latter group, although very much less than for employees first exposed before 1933. Among the 963 workers first exposed in 1933 or later, mortality was increased for carcinoma of the bronchus (31 deaths; 19-3 expected for all lung cancers) and non-malignant respiratory disease (35 deaths, 25-0 expected), and a further 5 deaths were attributed to pleural mesothelioma.
Antagonistic activity of poly (4-vinylpyridine-N-oxide) to the inhibition of viral interferon induction by asbestos fibres. N. Hahon, J.A. Booth, H.L. Eckert. 1977;34(2):119-25. PubMed · Publisher · Free full text

Abstract

The depressive activity of both serpentine (Canadian and Rhodesian chrysotiles) and amphibole (amosite, crocidolite, and anthophyllite) asbestos fibres on interferon induction by influenza virus was significantly diminished or abolished completely when either asbestos fibres or LLC-MK2 cell monolayers were pretreated with poly(4-vinylpyridine-N-oxide). Maximal antagonistic activity of the polymer was time and concentration dependent. Pretreating asbestos fibres with the polymer was more rapid and effective in encouraging viral interferon synthesis than pretreating cell monolayers. Virus multiplication in the presence of asbestos fibre-treated cell monolayers attained a twofold higher level than that noted in normal cell monolayers or those containing polymer-pretreated asbestos fibres. These findings were related to the suppression of interferon production.
Insulation workers in Belfast. A further study of mortality due to asbestos exposure (1940-75). P.C. Elmes, M.J. Simpson. 1977;34(3):174-80. PubMed · Publisher · Free full text

Abstract

A follow-up study of 162 men already working as insulators (laggers) in 1940 has been extended from 1965 to 1975. By the end of 1975 there were 40 survivors when 108 had been expected. Until 1965 there had been an overall excess of deaths; these were due to asbestosis with or without tuberculosis and to alimentary cancer, as well as to bronchial carcinoma and mesothelioma. From 1965 onwards the overall death rate among survivors is not so excessive but there is still a marked excess of deaths from bronchial cancer and mesothelioma. The continued risk of death attributable to malignancy after asbestosis had ceased to contribute directly, does not appear to be caused by any changes which occurred before 1940 in the conditions at work.
A proportional study of cancer registrations of dockyard workers. K.P. Lumley. 1976;33(2):108-14. PubMed · Publisher · Free full text

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Evidence of an occupational effect due to asbestos exposure was sought by comparing cancer registrations for dockyard workers with those for Plymouth men in the same age groups for 1960-69. The results show a significant excess of pleural tumours in the dockyard group but no significant excesses at other sites. Registrations for pleural mesothelioma were recorded for men with many dockyard occupations and the observed mean interval between first exposure to asbestos and registration for a pleural tumour (37.6 years) indicates that cases of pleural mesothelioma may be expected to occur among these workers for many years, even though crocidolite is no longer used in naval ships. A trend of increasing annual excess of stomach and gastrointestinal registrations was observed in the dockyard group. No cases of peritoneal mesothelioma were recorded but it is likely that some did occur which were diagnosed as cancers arising from other sites. This may account for some of the excess of gastrointestinal registrations.
Are glass fibres carcinogenic to man? A critical appraisal. J. Milne. 1976;33(1):47-8. PubMed · Publisher · Free full text
Predictions of mortality from mesothelial tumours in asbestos factory workers. M.L. Newhouse, G. Berry. 1976;33(3):147-51. PubMed · Publisher · Free full text

Abstract

Using the accumulated data on deaths from mesothelial tumours among cohorts of male and female factory workers at a London asbestos textile factory, the mortality from this cause up to the year 2000 AD has been predicted. The limitations of the methods used are pointed out, but it is estimated that for men the mortality due to mesothelial tumours will be between 7% and 11% of the total mortality and somewhat higher for women. The highest number of deaths from mesothelial tumours will occur during the 1980s, thereafter the numbers will decline because of the decreasing size of the cohort resulting from general mortality.
The biology of talc. G.Y. Hildick-Smith. 1976;33(4):217-29. Review PubMed · Publisher · Free full text

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Data are presented on the effects on health of talc dusts from exposure in industry and use of talc-containing health products. The mineralogy of talc and the composition of cosmetic and industrial grade talc dusts are described. Studies in animals are reviewed, and epidemiological data are considered in relation to exposures that occur during industrial and consumer uses of talc dusts. Hamsters exposed to 8 mg/m3 of respirable cosmetic grade talc dust for up to 150 minutes a day for 300 consecutive days showed no difference in incidence or nature of pathological lesions from those observed in a group of untreated animals. A retrospective study of the causes of death of 227 talc mine millers exposed to cosmetic grade talc at the threshold limit value for talc (20 million parts per cubic foot) for an average of 15-8 years showed that the causes of death were no different from those in a control cohort not exposed to talc dust. The available data indicate that talc dust exposure in the modern mining of cosmetic grade talc does not appear to be injurious to health. The significantly lower dust exposure in the normal use of cosmetic grade talc dusts in talc-containing health and cosmetic products confirms that their use is not a hazard to health.
Thirty-two cases of mesothelioma in Victoria, Australia: a retrospective survey related to occupational asbestos exposure. J.E. Milne. 1976;33(2):115-22. PubMed · Publisher · Free full text

Abstract

Mesotheliomas have been reported in four states in Australia. Crocidolite has been mined and milled at Wittenoom in West Australia where five cases of mesothelioma were reported after exposure of high intensity. The 32 cases of mesothelioma reported in this paper occurred during a period of 11 years in Victoria; 29 were pleural and three peritoneal. There were 22 autopsies. End occupations were misleading in 66% of cases. Two of the three subjects with peritoneal mesothelioma were siblings, and there was no evidence of occupational or other exposure to asbestos in either. There was a significant prevalence of pulmonary asbestos bodies in the tumour series as compared with an unselected consecutive series of 200 routine autopsies (0.01 greater than P greater than 0.001). The occupational history was as effective a method of assessing 'true' asbestos exposure as the pulmonary asbestos body count. Five cases had had a duration of exposure of one year or less, but they had had heavy exposure. The latent interval before tumour development was 25 years or longer in each case. There was no known exposure to asbestos in five cases (16%). The rare association of mesothelioma with types of asbestos other than crocikolite may not exist and could be explicable on the basis of the proportion (16%) of these tumours arising randomly in the population.
Effect of asbestos on lipid peroxidation in the red cells. S. Gabor, Z. Anca. 1975;32(1):39-41. PubMed · Publisher · Free full text

Abstract

In vitro exposure of red cells to vie International Union against Cancer (UICC) standard reference asbestos samples resulted in an increase of thiobarbituric acid substances. Chrysotiles developed the largest amounts of lipid peroxides, followed by anthophyllite, amosite, and crocidolite in decreasing order. Compared with the control samples erythrocytes free of dusts, all types of the asbestos examined disclosed significant differences. The results obtained provide support for the cytotoxic potential of amosite and crocidolite and, on the other hand, suggest that a lipid peroxidation of unsaturated fatty acids may be involved in the mechanisms(s) of membrane-damaging effects of asbestos dusts.
Prevalence of asbestos bodies in a necropsy series in East London: association with disease, occupation, and domiciliary address. I. Doniach, K.V. Swettenham, M.K. Hathorn. 1975;32(1):16-30. PubMed · Publisher · Free full text

Abstract

The prevalence of asbestos bodies was measured in lung sections in a necropsy series carried out at the London Hospital (1965-66) after exclusion of all known asbestos factory workers and cases of asbestosis and of mesothelioma. Associations were sought between the presence and number of asbestos bodies with the patients' sex, domiciliary address, occupation, industry, and diseases recorded at necropsy. Asbestos bodies were present in 42% of the 216 men in the series and in 30% of the 178 women. The number of bodies in the positive cases was small in comparison with the numbers seen typically in asbestosis; thus there were less than 6 asbestos bodies per 6-75 mm-3 lung tissue in 107 of the total 145 positive cases in contrast to 1 000 or more in asbestosis. In comparison with the overall series, an increased number of asbestos body positives was present in males with carcinoma of stomach and females with carcinoma of breast. In view of this finding lung sections were counted in further post-mortem examples of these carcinomas making a total of 50 males with carcinoma stomach and 82 females with carcinoma breast. Thirty-five positive cases were found in the carcinoma stomach group as against 22-7 expected and 38 in the carcinoma breast group against 26-35 expected. There was no excess of observed over expected asbestos body positives in 51 males with carcinoma of bronchus. There was an excess of asbestos body positives (60-9%) in heavy manual workers and in both heavy and light manual male workers in the shipping (61%), electrical and engineering (56%), and transport (54%) industries. The incidence in male clerical workers was 12-8%. The incidence of asbestos body positives according to home address was highest (53% in males, 45% in females) in patients living in the industrial and cockland area due east of the hospital. The incidence fell in the less industrial areas north-east of the hospital. Consideration of possible environmental sources of the inhaled asbestos suggests that in this survey occupation, industry, and comiciliary area all play a part. The comparatively minor intensity of asbestos pollution in our positive cases showed a positive association with carcinoma of stomach and breast, possibly playing a direct pathogenic role in carcinoma of stomach. No positive association was identified with any other neoplastic disease including carcinoma of bronchus.
Recent progress in the study of occupational lung diseases in Romania. B. Barhad, L. Pilat, D. Teculescu. 1975;32(2):164-8. Review PubMed · Publisher · Free full text

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This paper reviews studies of occupational lung diseases in Romania in the last two decades. Work concerned with the effects of exposure to textile fibres, irritant gases and fumes in the chemical industry, welding fumes, asbestos, cadmium oxide, and the relation between dust exposure, pneumoconiosis, and chronic bronchitis is briefly presented.
A study of the histological cell types of lung cancer in workers suffering from asbestosis in the United Kingdom. F. Whitwell, M.L. Newhouse, D.R. Bennett. 1974;31(4):298-303. PubMed · Publisher · Free full text

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Whitwell, F., Newhouse, Muriel, L., and Bennett, Diane R. (1974).British Journal of Industrial Medicine,31, 298-303. A study of histological cell types of lung cancer in workers suffering from asbestosis in the United Kingdom. The present study concerns the predominant cell type of lung cancer in workers with certified asbestosis who died of carcinoma of the lung in the United Kingdom between 1962 and 1972. Clinical data, necropsy reports, histological sections, and in some cases paraffin blocks were obtained from the nine pneumoconiosis panels in the country and from hospitals where the patients had been treated. Histological analysis was confined to the 88 male and nine female cases in which adequate postmortem tissue had been obtained. The number of female cases was considered to be too small to be of value as a separate series. Among the males, adenocarcinoma was the commonest type of lung cancer found in 34%. Information about the smoking habits of 69 of the 88 men was obtained; all had smoked at some time. There was little difference between the smoking habits of any group whatever the cell type of carcinoma. The difficulty in finding a comparable series of non-asbestos-exposed individuals is pointed out. It is the usual practice to hold a necropsy on any patient when asbestosis has been certified wherever the place of death. This series therefore has a wider basis of selection than any hospital-based series. Cigarette smoking can exert a carcinogenic effect on different parts of the bronchial tree, producing squamous or oat-celled tumours proximally and adenocarcinoma distally. Asbestos dust lying in distal parts of the lung may exert a co-carcinogenic probably a multiplicative effect with tobacco smoke, producing adenocarcinoma of the distal part of the respiratory tract.
A survey of occupational cancer in the rubber and cablemaking industries: results of five-year analysis, 1967-71. A.J. Fox, D.C. Lindars, R. Owen. 1974;31(2):140-51. PubMed · Publisher · Free full text

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Fox, A. J., Lindars, D. C., and Owen, R. (1974).British Journal of Industrial Medicine,31, 140-151. A survey of occupational cancer in the rubber and cablemaking industries: results of five-year analysis, 1967-71. A mortality study of 40 867 subjects employed in the rubber and cablemaking industries on 1 February 1967 is reported. No evidence is found of a continued excess risk of neoplasms of the bladder in people who entered the industry after 1949. For those employed before that date, during the period when known bladder carcinogens were in use, the SMR is higher than predicted, indicating that men are still dying with occupationally induced tumours. An excess of all neoplasms was noted in the five years of the study. In certain sections of the industry (tyre manufacture, belting hose rubber with asbestos, and flooring industry) there is a particular excess of bronchial carcinoma. In those sections which use asbestos such an excess is not altogether surprising, but this does not apply to the tyre industry. The latter industry is sufficiently large (16 035 men in the study compared with 4 350 in the belting, hose rubber with asbestos, and flooring industry) for attention to be focused on particular operations. Two job groups are found to share the excess: moulding, press, autoclave, and pan curemen; and finished goods, packaging, and despatch. Job selection may play a part in the latter, as the work is generally considered suitable for older and perhaps less healthy people. Crude analyses have been undertaken to indicate whether the excesses are due to regional differences or to the population comprising an abnormally high proportion of smokers. No excesses are found in other smoking-related diseases. Although the effects of differences in smoking habit and regional differences cannot be ruled out, the indications are against these factors being the primary cause. The difficulties of this type of study are discussed. It is emphasized that the results can be used only as an indication of a problem area and the type of further study required. A more exact study would concentrate on five-year cohorts of people who left the industry between 1940 and 1960. A study of five-year cohorts of people who entered the industry in the same period would also be valuable. An attempt has been made to perform the latter, but it would be hazardous to draw too many conclusions from this because the population comprises those who `survive' in the industry until 1967.
Mesothelioma register 1967-68. M. Greenberg, T.A. Davies. 1974;31(2):91-104. PubMed · Publisher · Free full text

Abstract

Greenberg, M., and Lloyd Davies, T. A. (1974).British Journal of Industrial Medicine,31, 91-104. Mesothelioma Register 1967-68. A register of mesothelioma cases is maintained by the Department of Employment, Medical Services Division (now Employment Medical Advisory Service). This paper describes an investigation of 413 notifications to the Register in 1967-68 from England and Wales and Scotland. Cases were regarded as `definite' when histological confirmation of diagnosis had been obtained, either by hospital pathologists, or by the UICC Panel of Pathologists, to whom pathological material was submitted whenever possible. Two hundred and forty-six cases were accepted as `definite' and 76 cases were regarded as `definitely not' mesothelioma. The remainder were classified as `undecided' or `insufficient pathological material'. Thirty-five of the 76 cases definitely not mesothelioma had nevertheless been so described on death certificates. The investigation carried out covers clinical aspects, survival, and evidence of exposure to asbestos. Twelve per cent of definite mesotheliomata were of peritoneal origin. The age range was 21 to 87 years, but, in general, mesothelioma occured at an earlier age than `carcinoma of bronchus and lung' or `all malignant tumours' in the Registrar General's statistical mortality tables. Concomitant asbestosis and the finding of asbestos bodies or pleural plaques occured as frequently in those cases classified as definitely not mesothelioma as in confirmed cases. Occupational exposure to asbestos was found in 68% of definite cases, apparently significantly more frequently than in those definitely not mesothelioma, but there was observer bias. The interval between the first exposure and death from mesothelioma exceeded 25 years in 85% of cases but was only three and a half years in one case. The duration of exposure varied widely: in 12% of cases it was under five years. The type of asbestos could be ascertained in so few cases that it was impossible to asses the rôle of crocidolite in aetiology. There were 38 definite cases in which no history of any exposure to asbestos could be obtained. Definite mesotheliomata showed marked clustering in areas where there is substantial industrial use of asbestos. Whether this should be interpreted as evidence of causation or an effect of heightened awareness in these areas cannot be deduced from this study. Evidence is quoted suggesting that the observed annual incidence of approximately 120 definite mesotheliomata in England, Scotland, and Wales may considerably understate the true prevalence.
Mortality and morbidity among the working population of anthophyllite asbestos miners in Finland. L.O. Meurman, R. Kiviluoto, M. Hakama. 1974;31(2):105-12. PubMed · Publisher · Free full text

Abstract

Meurman, L. O., Kiviluoto, R., and Hakama, M. (1974).British Journal of Industrial Medicine,31, 105-112. Mortality and morbidity among the working population of anthophyllite asbestos miners in Finland. A study has been made in Finland of the effects of anthophyllite asbestos on mortality and morbidity of 1 092 asbestos workers first employed at two mines between 1936 and 1969; 95% of workers were traced, 248 of whom had died. A similar number of age-sex-matched controls was selected from a township 60 km from the mines. The causes of death included an excess due to lung cancer and asbestosis, but cancers of the digestive system occurred in equal frequency, and neither the cases nor controls had any confirmed mesotheliomas. Assuming a multiplicative effect of asbestos and smoking, the relative risk of lung cancer was 17 for an asbestos worker who smokes in terms of a non-exposed non-smoker. The corresponding figures were 12 for a smoker without asbestos exposure and 1·4 for an asbestos worker who did not smoke. More heavy smokers were found among the asbestos workers than among the controls. A threefold excess of dyspnoea and a twofold excess of cough were recorded for the asbestos workers compared with the controls after adjustment for smoking.
Comparison of effects of glass fibre and glass powder on guinea-pig lungs. S.K. Botham, P.F. Holt. 1973;30(3):232-6. PubMed · Publisher · Free full text

Abstract

Botham, Susan K., and Holt, P. F. (1973).British Journal of Industrial Medicine,30, 232-236. Comparison of effects of glass fibre and glass powder on guinea-pig lungs. Following 24 hours inhalation by guinea-pigs of powdered glass dust, the pulmonary effects over the succeeding month differed from those previously observed to follow inhalation of glass fibre in that (1) fewer erythrocytes escaped from the capillaries, (2) very few giant cells were produced, (3) erythrocytes and intracellular glass particles were cleared more readily because junctions between respiratory and terminal bronchioles were not blocked by giant cells, (4) intracellular granules containing Perls-positive material did not appreciably increase in number or intensity of staining during the month, and (5) particles were not coated with Perls-positive material during the time that pseudo-asbestos bodies would be formed from glass fibres. The difference between the effects of chemically similar glass powder and fibre during a month in a guinea-pig lung is considered to be due to the morphology of the inhaled particle.
Computer simulation of industrial hazards. E.G. Knox. 1973;30(1):54-63. PubMed · Publisher · Free full text

Abstract

Knox, E. G. (1973).Brit. J. industr. Med.,30, 54-63. Computer simulation of industrial hazards. A computer simulation system for a range of industrial hazards provided for model experiments which manipulated (a) the sub-structure of an exposed population in terms of age-distributions and levels of exposure, (b) the nature of the dose/response relationship, (c) the latent interval and its variability, (d) normal life-table expectations, and (e) employment turnover rates. The development of the system led to clarification of terms and concepts with ambiguous current usages, notably in relation to latency. Distinction is made between the notions of `biological' and `observable' latent intervals. Hypothetical exercises with the model tested its technical validity and at the same time demonstrated in quantitative terms the relationships between `biological' and `observable' latent intervals, employment turnover rates, total mortalities, and the distribution of illnesses and death between those currently employed in the exposing industry, those employed elsewhere, and those retired. Prospects of success for personnel engineering techniques, which manipulate age-distributions of exposed work people in relation to diseases with long latent intervals, were examined. Published asbestos cancer data were used as a basis for specific model fitting and resulted in a numerical formulation of the exposure/response relationships. Severe exposure results in an increment of risk of death of about 0·02 unit per person per annum for those exposed for around six years, but with higher rates for shorter exposures and lower rates for longer ones. The mean biological latent interval was about 25 years with a coefficient of variation of about 25%. These suppositions explained a range of published data comprehensively and at the same time predicted that (a) persons exposed at severe levels for a working lifetime of 50 years have a 40% risk of dying from asbestos cancer, and (b) industrial populations with moderate to high turnover rates effect a form of extended dose sharing, and non-linearity of the exposure/response relationship results in substantially more deaths than would be the case if the turnover rate were lower.
Evaluation of the tumorigenic potential of vermiculite by intrapleural injection in rats. B. Hunter, C. Thomson. 1973;30(2):167-73. PubMed · Publisher · Free full text

Abstract

Hunter, B., and Thomson, C. (1973).British Journal of Industrial Medicine,30, 167-173. Evaluation of the tumorigenic potential of vermiculite by intrapleural injection in rats. Vermiculite, the geological name for a group of hydrated laminar minerals, has industrial application in areas previously restricted to the use of asbestos. In this assessment of its tumorigenicity, Rhodesian chrysotile asbestos or vermiculite was injected into the pleural cavity of rats. Mesotheliomata developed in 48% of the rats treated with asbestos. No tumours occurred which were associated with the vermiculite injections.
Histochemical study of asbestos fibre coating in experimental carrageenin granulomas. M. Governa, C. Rosanda Vadalá. 1973;30(3):248-52. PubMed · Publisher · Free full text

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Governa, M., and Rosanda Vadalà, C. (1973).British Journal of Industrial Medicine,30, 248-252. Histochemical study of asbestos fibre coating in experimental carrageenin granulomas. To study the composition of asbestos body coating, asbestos particles present in experimental carrageenin granulomas were tested histochemically for mucopolysaccharides, ferric and ferrous iron, haemoglobin, and haematoidin. The stains were applied on microscopical sections both untreated and treated with iron-extracting solutions and/or enzymes. The results indicate that asbestos is rapidly coated with haematoidin, ferric iron, and hyaluronic acid.
Report of the Advisory Committee on Asbestos Cancers to the Director of the International Agency for Research on Cancer. 1973;30(2):180-6. PubMed · Free full text

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In 1964 the Geographical Pathology Committee of the International Union against Cancer (UICC) set up a working group on asbestos and cancer and later issued a Report and Recommendations (1965). A further meeting was held at the International Agency for Research on Cancer (IARC), Lyon, France, on 5 and 6 October 1972. This was organized jointly with the Medical Research Council Pneumoconiosis Research Unit. The report and recommendations given here will also be published by IARC in 1973, together with the complete proceedings of the meeting. The Committee consisted of three panels—Epidemiology, Pathology, and Physics and Chemistry.
Respiratory cancer in relation to occupational exposures among retired asbestos workers. P. Enterline, P. de Coufle, V. Henderson. 1973;30(2):162-6. PubMed · Publisher · Free full text

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Enterline, P., de Coufle, P., and Henderson, V. (1973).British Journal of Industrial Medicine,30, 162-166. Respiratory cancer in relation to occupational exposures among retired asbestos worker. A cohort of 1 348 men who completed their working lifetime in the asbestos industry and retired with an industry pension during the period 1941-67 was observed through 1969 for deaths. The average length of employment in the asbestos industry for these men was 25 years and all had exposures to asbestos dust. In some instances these exposures were very high and continued for many years. Mortality for this cohort of men after age 65 was 14·7% higher than for the entire population of United States white men living at the same ages and time periods. This excess was due almost entirely to cancer and respiratory disease. The cancer excess was chiefly due to respiratory cancer where mortality was 2·7 times the expected. The respiratory disease excess was entirely due to asbestosis. A time-weighted measure of asbestos dust exposure at the time of retirement was calculated for each man. This was made up of the summed products of dust levels for each job (expressed in mppcf) and years at each level. This measure was directly related to the respiratory cancer excess at ages 65 and over, ranging from 1·7 times expected for men with less than 125 mppcf-years exposure to 5·6 times expected for men with 750 or more mppcf-years exposure. There appeared to be no direct relationship between asbestos dust exposure and respiratory cancer below 125 mppcf-years. Important increments in respiratory cancer mortality apparently occurred somewhere between 100 and 200 mppcf-years exposure. Separation of the effects of time from the effects of average dust level on respiratory cancer mortality showed that the contribution of each was about the same and that a time-weighted measure of asbestos dust appears to be an appropriate method for predicting respiratory cancer effects.
A histochemical study of the asbestos body coating. M. Governa, C. Rosanda. 1972;29(2):154-9. PubMed · Publisher · Free full text

Abstract

Governa, M., and Rosanda, C. (1972).Brit. J. industr. Med.,29, 154-159. A histochemical study of the asbestos body coating. Asbestos bodies after iron extraction were tested by histochemical methods for mucopolysaccharides. The results of the reactions suggest that acid mucopolysaccharides are present in the coating of most bodies. During the formation of the bodies acid mucopolysaccharides might act as a matrix for iron deposition on the coating.
A mortality study of shipyard workers with pleural plaques. D.E. Fletcher. 1972;29(2):142-5. PubMed · Publisher · Free full text

Abstract

Fletcher, D. E. (1972).Brit. J. industr. Med.,29, 142-145. A mortality study of shipyard workers with pleural plaques. Mild asbestos effects are seen frequently in shipyard workers. It is known that exposure of this type may be associated with mesothelioma, but it is not generally thought that an increased bronchial carcinoma risk exists unless there is pulmonary fibrosis. A number of cases of both types of malignant disease were seen in the Barrow hospitals, associated with pleural plaques. In view of this a retrospective survey was carried out. All routine administrative chest films taken in the works clinic between 1960 and 1970 were reviewed, together with the films of the 1962 mass radiography session, and 408 men were found to have evidence of pleural plaques. The men were followed up from the year of diagnosis until 1970 and 65 men died in this period. A similar control group of 404 men was chosen and 56 of them died. Both groups were compared with the expected mortality of Barrow men of the same age groups. There were 16 bronchial carcinomas in the plaque series compared with an expected figure of 6·74 (P = 0·0047), while in the control series there were 7 bronchial carcinomas compared with 5·61 expected (P = 0·516). Three mesotheliomas occurred in the plaque series (P = 0·0002).
A study of the mortality of female asbestos workers. M.L. Newhouse, G. Berry, J.C. Wagner, et al. 1972;29(2):134-41. PubMed · Publisher · Free full text

Abstract

Newhouse, M. L., Berry, G., Wagner, J. C., and Turok, M. E. (1972).Brit. J. industr. Med.,29, 134-141. A study of the mortality of female asbestos workers. A cohort study of over 900 women employed at an asbestos factory making both textiles and insulation materials is described. It extends the information about asbestos-related disease at this factory which was previously available only for male workers. The cohort was defined as all the women who started employment at the factory between 1936 and 1942 and the main analysis was of mortality up to the end of 1968. This analysis was made in relation to job, length of exposure, and age at first exposure. Compared with national rates there was excess overall mortality among those who worked in jobs with low to moderate exposure partly accounted for by deaths from cancer. In the group with severe exposure, who had worked in the factory for less than two years, there was an excess of cancer of the lung and pleura. However, the most marked increased mortality was in those with severe exposure who had worked for more than two years in the factory; in this group there were excess deaths from cancer of the lung and pleura, from other cancers, and from respiratory diseases. There were no significant trends of excess mortality with age at first exposure. The smoking habits of some of the deceased women were obtained and the indications were that the proportion of smokers in the cohort was higher than the national rate. This could account for some of the excess mortality but the trend of this excess with exposure indicated the role of asbestos. Necropsy reports and/or histological material were obtained for 43% of those who had died. Three deaths registered as cancer of the pleura were identified as pleural mesothelial tumours; in all there were 11 mesotheliomas, six of pleural and five of peritoneal origin.
Absorption of serum proteins by inorganic dusts. B.M. Jones, J.H. Edwards, J.C. Wagner. 1972;29(3):287-92. PubMed · Publisher · Free full text

Abstract

Jones, B. M., Edwards, J. H., and Wagner, J. C. (1972).Brit. J. industr. Med.,29, 287-292. Absorption of serum proteins by inorganic dusts. Four samples of coal dust of different ranks, five types of asbestos, and a sample of silica were each incubated with normal serum and with IgG and the amount of protein absorbed onto the particle surfaces was estimated. The total amount of protein absorbed by the coal samples was not related to the rank of coal, and surface absorption by the dusts did not detectably alter protein to a form capable of reacting with rheumatoid factor, the latter finding being in disagreement with the hypothesis put forward by Payne (1963) to explain the presence of rheumatoid factor in the serum of a large proportion of coal workers with pneumoconiosis. Estimation of immunoglobulin levels after incubation of normal serum with 10 samples of coal suggested that IgG might be selectively absorbed, and RF was absorbed in preference to normal serum proteins by dust samples which had not been coated with normal serum.
Comparison of effects on macrophage cultures of glass fibre, glass powder, and chrysotile asbestos. E.G. Beck, P.F. Holt, N. Manojlović. 1972;29(3):280-6. PubMed · Publisher · Free full text

Abstract

Beck, E. G., Holt, P. F., and Manojlović, N. (1972).Brit. J. industr. Med.,29, 280-286. Comparison of effects on macrophage cultures of glass fibre, glass powder, and chrysotile asbestos. The effects on macrophage cultures of glass fibre, glass powder, and chrysotile asbestos are compared. Glass fibre behaves like chrysotile in producing an increase in cell membrane permeability in cultured macrophages. This is demonstrable by the increase in lactic dehydrogenase activity in the supernatant fluid. The metabolism, measured by lactate production, is not reduced as it is when quartz is phagocytosed. Glass powder behaves like the inert dust corundum, producing little change in the number of cells stained by erythrosin B and a small increase in lactate dehydrogenase activity, both being in the range of the control. There is an increase in lactate production as a result of higher metabolism due to phagocytosis. Dusts may produce two basic effects, namely a toxic effect and change in cell membrane permeability. A non-specific effect on the cell membrane due to the slow and sometimes incomplete process of ingestion of long fibres is probably a function of the morphology, particularly the length of the fibres. A primary specific effect induced by some dusts immediately follows contact with the cell membrane.
Electron microscope characteristics of inhaled chrysotile asbestos fibre. F.D. Pooley. 1972;29(2):146-53. PubMed · Publisher · Free full text

Abstract

Pooley, F. D. (1972).Brit. J. industr. Med.,29, 146-153. Electron microscope characteristics of inhaled chrysotile asbestos fibre. Specimens from 300 lungs have been examined under the electron microscope to determine the morphology and diffraction characteristics of any chrysotile asbestos they contained. In 120 cases, material was prepared by alkali digestion and the residual dust was examined. In all cases standard 6-micron histological slides were partially ashed before the residue was transferred to the electron microscope grids. Of the 300 specimens examined, 20 came from men with prolonged industrial exposure to chrysotile, 87 from cases of mesothelioma, and the remainder from control groups drawn from rural and industrial populations. Chrysotile fibres were readily identified by the characteristic polycrystalline diffraction pattern. The hollow appearance of the single fibres and their shape and arrangement also help in the identification. Specimens from men without industrial exposure contained either single short fibres or aggregates scattered throughout the lungs. In specimens from industrially exposed men, fibres were very numerous and found as strands of single fibres mainly grouped together in discrete locations. Ferruginous bodies were found rarely and only on straight fibre bundles of over several micrometers in length.
Epidemiology of pleural mesothelioma in North-western Italy (Piedmont). G.F. Rubino, G. Scansetti, A. Donna, et al. 1972;29(4):436-42. PubMed · Publisher · Free full text

Abstract

Rubino, G. F., Scansetti, G., Donna, A., and Palestro, G. (1972).Brit. J. industr. Med.,29, 436-442. Epidemiology of pleural mesothelioma in North-western Italy (Piedmont). Fifty-four cases of mesothelioma of the pleura admitted to the Chest Surgery Centre or to the Department of Medicine of the University of Turin from 1960 to 1970 are reported. Thoracotomy was performed in 22. In the other 32 the diagnosis was based on the clinical, radiographic, and cytological findings and on the results of biopsy. In 50 cases (18 women and 32 men), the majority of whom had always or mostly lived in Piedmont, it was possible to ascertain the family history, previous residence, and occupation, mainly with the aid of information given by the patient's relatives. A similar investigation was made by the same interviewers into 50 other patients of the same sex and age admitted to the same institutions, using an identical technique. In the group with mesothelioma (only two of whom survived more than two years after the diagnosis had been made) occupational exposure to asbestos was demonstrated unequivocally in five men. Three other patients, including one woman, had lived with persons employed in the asbestos industry (16%). Exposure for occupational reasons seemed very likely in another patient, who had been a fireman in the Turin Arsenal for 40 years. One man in the control group had worked for two years in a cement-asbestos manufacturing company (2%). A re-appraisal of the histological sections and examination of new preparations made in the 22 cases operated on was done in the Department of Pathological Anatomy of the University of Turin, also with the purpose of confirming the diagnosis. This re-appraisal revealed the presence of asbestos bodies in the mesothelioma in one case, a woman who had never been exposed to asbestos for occupational or domestic reasons but who had always lived in one of the two regions of the Province of Turin with the highest number of asbestos industries.
Radiological survey of men exposed to asbestos in naval dockyards. P.G. Harries, F.A. Mackenzie, G. Sheers, et al. 1972;29(3):274-9. PubMed · Publisher · Free full text

Abstract

Harries, P. G., Mackenzie, F. A. F., Sheers, G., Kemp, J. H., Oliver, T. P., and Wright, D. S. (1972).Brit. J. industr. Med.,29, 274-279. Radiological survey of men exposed to asbestos in naval dockyards. Asbestos related abnormalities were found in 3% of a 10% sample population in radiological surveys of the naval dockyards at Portsmouth, Chatham, and Rosyth. The prevalence of these abnormalities was related to the type of occupation and duration of exposure to asbestos. The results confirm the findings of an earlier survey at Devonport dockyard. No association between smoking, or the amount smoked, and the incidence of parenchymal or pleural disease due to asbestos was detected. Pleural abnormalities were found 10 times more frequently than parenchymal disease, and concern is felt over the uncertainty of the prognosis in men with pleural abnormalities, especially as 37 men have developed pleural mesothelioma at Devonport since 1965. More work is required to establish the true significance of pleural abnormalities caused by asbestos and to explore possible methods of treatment.
Effects of chrysotile and acid-treated chrysotile on macrophage cultures. E.G. Beck, P.F. Holt, E.T. Nasrallah. 1971;28(2):179-85. PubMed · Publisher · Free full text

Abstract

Beck, E. G., Holt, P. F., and Nasrallah, E. T. (1971).Brit. J. industr. Med.,28, 179-185. Effects of chrysotile and acid-treated chrysotile on macrophage cultures. The addition of chrysotile asbestos to monolayer cultures of peritoneal and alveolar macrophages produces an increase in membrane permeability, as measured by eosin uptake and lactic dehydrogenase activity of the supernatant fluid. The lactate synthesis is increased, however. It is suggested that the permeability of the cell membrane is increased while dust particles are being phagocytosed, which may take several hours when the particles are fibrous, but that this does not imply cell damage. Treatment of chrysotile with acid, which leaves a silica surface, results in a product that reduces lactate synthesis, implying cytotoxicity. This change is counteracted by poly(2-vinyl-pyridine 1-oxide). The polymer does not affect the properties of the native chrysotile.
Epidemiology of mesothelioma on Walcheren Island. J. Stumphius. 1971;28(1):59-66. PubMed · Publisher · Free full text

Abstract

Stumphius, J. (1971). Brit. J. industr. Med., 28, 59-66. Epidemiology of mesothelioma on Walcheren Island. The chance finding of asbestos bodies without `asbestosis' in the lungs of a shipyard worker who had not worked directly with asbestos led to this investigation into the relationship between asbestos bodies in the sputum, occupation, and mesothelioma in the shipyard at Vlissingen on Walcheren Island. Examination of the sputum from a sample of 277 shipyard workers from various occupation groups (excluding insulation workers and others known to work continuously with asbestos) showed `asbestos' bodies to be present in 60%. The frequency varied from 39% in workers with no obvious exposure to asbestos dust to 100% among those with slight but definite exposure. By repeating the analysis using the occupations 5 to 10 years previously it was found that many of the workers currently employed in occupations not exposed to asbestos who had asbestos bodies in their sputum had been exposed in the past. Between 1962 and 1968, 25 cases of mesothelioma were discovered on Walcheren; of these, 22 cases had been employed in the shipyard at some time and their actual job was known in all but one case. The shipyard employs approximately 3 000 men so that the attack rate for mesothelioma was approximately 100 per 100 000 males per year. For Dutch provinces with heavy industry the rate is 1·0 per 100 000 per year. For the different occupational categories within the shipyard the rates varied from approximately 50 for `clean work' to 280 for men with some exposure to asbestos dust. Asbestos insulation workers were not included in the study and no cases of mesothelioma came from that occupational group.
Insulation workers in Belfast. 1. Comparison of a random sample with a control population. W.F. Wallace, J.H. Langlands. 1971;28(3):211-6. PubMed · Publisher · Free full text

Abstract

Wallace, W. F. M., and Langlands, J. H. M. (1971).Brit. J. industr. Med.,28, 211-216. Insulation workers in Belfast. 1. Comparison of a random sample with a control population. A sample of 50 men was chosen at random from the population of asbestos insulators in Belfast and matched with a control series of men of similar occupational group with respect to age, height, and smoking habit. Significantly more of the insulators complained of cough and sputum and had basal rales on examination. Clubbing was assessed by means of measurements of the hyponychial angle of both index fingers. These angles were significantly greater in the group of insulators. Twenty-one insulators had ϰ-rays which showed pleural calcification with or without pulmonary fibrosis; one control ϰ-ray showed pulmonary fibrosis. The insulators had no evidence of airways obstruction but static lung volume was reduced and their arterial oxygen tension was lower than that of the controls and their alveolar-arterial oxygen gradient was greater.
Insulation workers in Belfast. 2. Morbidity in men still at work. J.H. Langlands, W.F. Wallace, M.J. Simpson. 1971;28(3):217-25. PubMed · Publisher · Free full text

Abstract

Langlands, Jean H. M., Wallace, W. F. M., and Simpson, Marion J. C. (1971).Brit. J. industr. Med.,28, 217-225. Insulation workers in Belfast. 2. Morbidity in men still at work. Two hundred and fifty-two (93%) of the insulation workers in Belfast were examined by chest ϰ-ray, questionnaire, clinical examination, and tests of respiratory function. The frequency of chest ϰ-ray abnormality, lung field or pleural, increased from 13% in men who had worked for less than 10 years to 85% in men who had worked for 30 or more years in the industry. Pleural calcification was found in 15 ϰ-rays. There was evidence suggesting that some men had pleural fibrosis or calcification due to exposure to asbestos in childhood. Rales were present in 61% and clubbing in 11% of men with lung field abnormality, but these were not common when the ϰ-rays showed only pleural abnormality. Where the lung fields were involved there was a restrictive defect with impairment in lung function most marked in the forced vital capacity and single breath carbon monoxide transfer factor, but where the pleura was involved without lung field involvement there was a tendency to impairment of ventilatory function with a normal transfer factor. Cigarette smoking was associated with a greater impairment of lung function than was ϰ-ray abnormality.
Insulation workers in Belfast. 3. Mortality 1940-66. P.C. Elmes, M.J. Simpson. 1971;28(3):226-36. PubMed · Publisher · Free full text

Abstract

Elmes, P. C., and Simpson, Marion J. C. (1971).Brit. J. industr. Med.,28, 226-236. Insulation workers in Belfast. 3. Mortality 1940-66. One hundred and seventy men were identified as making up the total population of insulation workers in Belfast in 1940. This is an analysis of all the information about deaths that has emerged from tracing these men up to the end of 1966. Five remain untraced, and the mortality experience of the remainder is compared with that of other men in Northern Ireland over the period. There were 98 deaths when only 37 were expected. The number of deaths occurring exceeded those expected throughout the period 1940-66 and the increase was statistically significant during the period 1950-55 and onwards. There was an especially high mortality (compared with other Northern Ireland males) due to cancer of the lung, mesothelioma of the pleura and peritoneum, cancer of the gastrointestinal tract, and fibrotic lesions of the lungs. The ratio of observed over expected deaths was 2·6 for all causes, 3·9 for all cancers, and 17·6 for cancers of the lower respiratory tract and pleura. Those men finally classified as dying from lung cancer showed evidence of lung fibrosis whereas those classified as dying from mesothelioma did not. Comparisons within the group failed to show any relationship between age at first exposure or duration of exposure and the excessive mortality. There were too few non-smokers to show the significance of smoking.

1960s

A study of the mortality of workers in an asbestos factory. M.L. Newhouse. 1969;26(4):294-301. PubMed · Publisher · Free full text

Abstract

Newhouse, M. L. (1969).Brit. J. industr. Med.,26, 294-301. A study of the mortality of workers in an asbestos factory. A cohort study of over 4,500 male workers employed at an asbestos factory making both textiles and insulation materials is described. The main analysis of the mortality of workers employed between April 1, 1933, the date of the implementation of the Asbestos Regulations, and May 1, 1964. The analysis was made in relation to job, length of exposure, and length of follow-up after first exposure. There was no significant difference between the number of deaths occurring in the factory population and the national figures, until an interval of 16 years or longer had elapsed from first exposure in the factory. There were 1,160 men who fulfilled this criterion. In this group there was no excess mortality among those who worked in jobs where exposure was low or moderate, but among those with jobs which entailed heavy exposure there was a significant excess of deaths from cancer of the lung and pleura, and cancer of other sites, in men with a total period of employment in the factory of less than two years, as well as with those who worked for longer. Excess mortality from respiratory disease was observed only among severely exposed workers with long service.
Validation of death certificates in asbestos workers. M.L. Newhouse, J.C. Wagner. 1969;26(4):302-7. PubMed · Publisher · Free full text

Abstract

Newhouse, M. L., and Wagner, J. C. (1969).Brit. J. industr. Med.,26, 302-307. Validation of death certificates in asbestos workers. The Registrar General has supplied the certified cause of death of 436 past workers in an asbestos factory. An attempt was made to follow up the 301 (69%) deaths which had occurred in hospital or had been the subject of an inquest or coroner's post-mortem examination. Necropsy reports were obtained for 158 (52%) of this group and histological material was reviewed in 84 (28%). The additional information, particularly that obtained from review of the histology, led to the revision and extension of the diagnosis suggested by the certified cause of death in a number of cases. The incidence of carcinoma of the bronchus had not been grossly underestimated, four additional tumours of this type were identified by scrutiny of the necropsy reports, and a further four by review of histological sections. The incidence of mesothelial tumours was underestimated, endothelioma or mesothelioma was the certified cause of death in four of the series, and a further 15 mesotheliomata were identified by review of histological material. Five patients with pleural mesotheliomata had been certified as dying of carcinoma of the lung or pleura. Ten deaths from peritoneal mesotheliomata had been attributed either to carcinomatosis without mention of a primary tumour or to cancer of the gastro-intestinal tract. Lung sections were submitted for review in 67 of the series; some degree of asbestosis was found in all but seven. Asbestosis graded as either moderate or severe was found in all the confirmed cases of carcinoma of the lung.
Mortality from lung cancer and other causes among workers in an asbestos textile factory. J.F. Knox, S. Holmes, R. Doll, et al. 1968;25(4):293-303. PubMed · Publisher · Free full text

Abstract

An account is given of work in an asbestos textile factory and of the steps taken to reduce exposure to dust since the introduction of the Asbestos Industry Regulations in 1931. Measurements of the amount of dust to which men were exposed in the scheduled areas have been made by various methods since 1951, but the data obtained by these methods are not directly comparable. Measurements made since 1960 show that the mean yearly dust level has been fairly constant from year to year and has varied from place to place between 1 and 8 particles (5 to 100 microns long and at least three times as long as they were wide) per c.c. of air. Chrysotile was used predominantly in the factory, but small amounts of crocidolite were also processed at all relevant periods. Death rates have been recorded for all the 256 men who were employed for at least 20 years in the scheduled areas since the first man completed 20 years' exposure in 1916, and for the 538 men and 220 women who were employed for at least 10 years in the scheduled areas but were never employed in these areas before 1933. The results show a substantially increased mortality for men who were exposed for 10 or more years before 1933 (48 deaths from all causes against 17·1 expected). The increased mortality among these men can be accounted for by an increased mortality from cancer of the lung (12 deaths against 1·2 expected) and from diseases of the respiratory and circulatory systems associated with asbestosis. Men employed before 1933, but for less than 10 years, showed an increased mortality from lung cancer (5 deaths against 2·6 expected), but no significant increase from other causes. Men and women who were exposed only since January 1, 1933, have had a mortality experience close to the national average. Analysis of the trends in mortality shows (1) a decrease in mortality from lung cancer and other deaths associated with asbestosis with reduction in length of employment before 1933, and (2) an increase in mortality from lung cancer and other deaths without asbestosis with age. Twenty-three cases of lung cancer occurred in men who had been employed in the scheduled areas for at least 20 years. One was regarded as a pleural mesothelioma and the rest (approximately 18 in excess of expected) appear to have been ordinary bronchial carcinomas. Four other mesotheliomas have been diagnosed since 1963, all in men and women with less than 10 years' exposure, one with only seven months' exposure, and one in a man who had been employed in the scheduled areas only since 1937. The results provide grounds for believing that the occupational hazard of bronchial carcinoma has been largely eliminated, but the data are insufficient to estimate the extent of the risk which may remain.
The Newcastle Papers in Industrial Medicine over the last 21 years. R.C. Browne. 1968;25(3):187-95. PubMed · Publisher · Free full text

Abstract

The Chair of Industrial Health in Newcastle upon Tyne was first filled in March, 1946. For about the first 12 years diseases of coalminers posed the main clinical and research problems. They stimulated surveys of pneumoconiosis in the Durham and Northumberland coalfields and led to studies of ϰ-ray viewing techniques and of the relationship of radiological appearance to symptoms in dust disease of the chest. A section of medical statistics, now headed by a professor, was one of the earliest elements of the department to be inaugurated, and this was followed by a section of pulmonary physiology. The emphasis on industrial pulmonary disease, on which 14 papers have been published, has gradually widened and become transferred from coal to beryllium, asbestos, and antimony. Coalminers with nystagmus were shown to be socially similar to miners without the disease but psychologically less stable. They also suffered from a breakdown of their binocular vision. A darkness-induced nystagmus was experimentally produced in kittens, with increasing difficulty as they became older. Decompression sickness has become an important interest. In the build-up of the department demands for occupational hygiene soon led to the formation of a section which started work on the decalcification of teeth by organic acids in a fruit salt factory. Lead poisoning in shipbreakers and smelters, and vanadium poisoning in fitters and gasmakers were studied jointly with clinicians. The thermal decomposition of protective coatings and welding rods has also attracted research, as also have the noise levels in a glassblowing school and in several power stations. All medical, engineering, and public health undergraduates are taught by the department, and also the honours chemists. All medical undergraduates and honours engineers are examined in industrial health. The departmental budget (including the field service) is about £54,000, and the department inhabits 12,660 sq. ft. of space.
Investigation of a minor asbestos hazard. M.C. Kennedy, R. Routledge. 1967;24(3):232-9. PubMed · Publisher · Free full text

Abstract

Twelve men who had been exposed to a minor asbestos hazard have been examined clinically, radiologically, and physiologically, and an assessment of the airborne asbestos concentration has also been made. Ten men had worked in a transformer department lagging transformer windings with asbestos paste for between 15 and 37 years. Two of these men showed minor radiological and minor physiological changes suggestive of early asbestosis. Two insulation workers had been engaged in milling and sawing asbestos sheets for five and 23 years respectively; both men showed minor radiological and abnormal physiological changes. These two men had been exposed to higher airborne concentrations of the asbestos dust than the transformer men. It is impossible to be dogmatic concerning the aetiology of these pulmonary changes, and further follow-up studies are planned. However, the findings are presented in view of the recommendation by Gilson (1966) that more evidence is required concerning possible pulmonary changes in men exposed to low concentrations of asbestos.
Mesothelioma of pleura and peritoneum following exposure to asbestos in the London area. M.L. Newhouse, H. Thompson. 1965;22(4):261-9. Case report PubMed · Publisher · Free full text

Abstract

A series of 83 patients from the London Hospital with a diagnosis of mesothelioma confirmed by necropsy or biopsy has been studied for possible exposure to asbestos. The series consisted of 41 men and 42 women; 27 of the patients had peritoneal and 56 pleural tumours. The earliest death recorded was in 1917, but only 10 of the series died before 1950 and 40 (48%) between 1960 and 1964. In 76 of the series full occupational and residential histories were obtained. Forty (52·6%) gave a history of occupational or domestic (living in the same house as an asbestos worker) exposure to asbestos compared with nine (11·8%) out of 76 patients from the same hospital suffering from other diseases (p < 0·001). None of the 17 suspected cases of mesothelioma, rejected on pathological grounds, was found to have had any exposure to asbestos. There was also evidence that neighbourhood exposures may be important. Among those with no evidence of occupational or domestic exposures, 30·6% of the mesothelioma patients and 7·6% of the in-patients with other diseases lived within half a mile of an asbestos factory (p < 0·01). Out of the 31 patients with occupational exposures only 10 were in jobs scheduled under the Asbestos Regulations of 1931. The interval between first exposure and the development of the terminal illness of mesothelioma ranged between 16 and 55 years. In 47 patients in the mesothelioma series, lung tissue or sputum was available for examination. In 30 (62·5%), either asbestosis or asbestos bodies were present.
A follow-up study of workers from an asbestos factory. P.C. Elwood, A.L. Cochrane, I.T. Benjamin, et al. 1964;21(4):304-7. PubMed · Publisher · Free full text

Abstract

Associations between exposure to asbestos and carcinoma of the lung, diffuse mesothelioma of the pleura, and diffuse abdominal tumours have been demonstrated. Only by an epidemiological approach can the total risks of exposure to asbestos be estimated, and such a study is reported here. This suggests that white asbestos (chrysotile) may not be a serious hazard as far as mesothelioma or abdominal tumours are concerned, though there is some evidence of an excess in the number of deaths from carcinoma of the lung and bronchus.
Peritoneal tumours in asbestosis. J.B. Enticknap, W.J. Smither. 1964;21(1):20-31. PubMed · Publisher · Free full text

Abstract

Eleven cases of diffuse abdominal tumours in association with exposure to asbestos were discovered in the years 1958 to 1963. There were eight men and three women, all of whom had worked at the same factory. In seven of the men the age at death ranged from 38 to 78 years; one man is still alive at the age of 46. The women died at 44, 61, and 67. The survival time after the first exposure varied from 20 to 46 years. The shortest period of exposure was 10 months and the longest 32 years. All three of the main commercial types of asbestos had been involved in their working operations. Histological confirmation of the nature of the tumour has been obtained at necropsy in nine of the 10 deceased and at biopsy in six, including the survivor. A remarkable feature of these cases is the minimal fibrosis found in the lungs. In three men and one woman, asbestosis was not diagnosed during life, and no patient was completely disabled by pulmonary fibrosis.
Asbestosis in experimental animals. J.C. Wagner. 1963;20(1):1-12. PubMed · Publisher · Free full text

Abstract

Previous animal experiments with asbestos dusts have been almost entirely confined to chrysotile asbestos. It was, therefore, decided to investigate the effects of mill dusts from the three types of asbestos that are produced commercially in South Africa, namely chrysotile, amosite, and crocidolite. Chrysotile and amosite samples were relatively pure while in contrast the crocidolite dust was found to consist mainly of ironstone and silica and contained less than 10% of asbestos fibre. Guinea-pigs, Vervet monkeys, and rabbits were exposed to these dusts. The results were assessed on histological criteria. It was found that, in all three species of animals, the amosite dust produced more marked lesions than the chrysotile and that these lesions occurred at an earlier period. It was not possible to compare these lesions with those caused by the crocidolite dust, owing to its impure nature. It was noted, however, that this dust caused severe lesions in guinea-pigs and monkeys and that the animals in this group succumbed more readily to respiratory infections.
Diffuse pleural mesothelioma and asbestos exposure in the North Western Cape Province. J.C. Wagner, C.A. Sleggs, P. Marchand. 1960;17(4):260-71. Case report PubMed · Publisher · Free full text

Abstract

Primary malignant tumours of the pleura are uncommon. Thirty-three cases (22 males, 11 females, ages 31 to 68) of diffuse pleural mesothelioma are described; all but one have a probable exposure to crocidolite asbestos (Cape blue). In a majority this exposure was in the Asbestos Hills which lie to the west of Kimberley in the north west of Cape Province. The tumour is rarely seen elsewhere in South Africa.
The relation between lung dust and lung pathology in pneumoconiosis. G. Nagelschmidt. 1960;17(4):247-59. PubMed · Publisher · Free full text

Abstract

Methods of isolation and analysis of dust from pneumoconiotic lungs are reviewed, and the results of lung dust analyses for different forms of pneumoconiosis are presented. A tentative classification separates beryllium, aluminium, abrasive fume, and asbestos, which cause interstitial or disseminated fibrosis from quartz, coal, haematite, talc, kaolin, and other dusts, which cause a nodular or focal fibrosis which may change to forms with massive lesions. The data suggest that in the first, but not in the second, group the dusts are relatively soluble; only in the second group do amounts of dust and severity of fibrosis go in parallel for a given form of pneumoconiosis. In classical silicosis the quartz percentage is higher and the amount of total dust much lower than in coal-miners' pneumoconiosis. Mixed forms of both groups occur, for instance, in diatomite workers. The need for more research, especially in the first group, is pointed out.

1950s

Mortality from lung cancer in asbestos workers. R. Doll. 1955;12(2):81-6. PubMed · Publisher · Free full text

Abstract

The cause of death, as determined at necropsy, is reported for 105 persons who had been employed at one asbestos works. Lung cancer was found in 18 instances, 15 times in association with asbestosis. All the subjects in whom both conditions were found had started employment in the industry before 1923 and had worked in the industry at least nine years before the regulations for the control of dust had become effective. One hundred and thirteen men who had worked for at least 20 years in places where they were liable to be exposed to asbestos dust were followed up and the mortality among them compared with that which would have been expected on the basis of the mortality experience of the whole male population. Thirty-nine deaths occurred in the group whereas 15.4 were expected. The excess was entirely due to excess deaths from lung cancer (11 against 0.8 expected) and from other respiratory and cardiovascular diseases (22 against 7.6 expected). All the cases of lung cancer were confirmed histologically and all were associated with the presence of asbestosis. From the data it can be concluded that lung cancer was a specific industrial hazard of certain asbestos workers and that the average risk among men employed for 20 or more years has been of the order of 10 times that experienced by the general population. The risk has become progressively less as the duration of employment under the old dusty conditions has decreased.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

1940s

Talc pneumoconiosis. A.I. McLAUGHLIN, E. Rogers, K.C. Dunham. 1949;6(3):184-94. PubMed · Publisher · Free full text

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