Mortality and cancer morbidity in cohorts of asbestos cement workers and referents

Our plain-English summary of Mortality and cancer morbidity in cohorts of asbestos cement workers and referents, by M. Albin, K. Jakobsson, R. Attewell, et al (British Journal of Industrial Medicine, 1990).

The study

• Authors: M. Albin, K. Jakobsson, R. Attewell, L. Johansson, H. Welinder
• Journal: British Journal of Industrial Medicine
• Published: 1990;47(9):602-10
• Cited by: 90 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 003763).

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).

In plain English

This study followed 1929 Swedish male workers at an asbestos cement plant in southern Sweden. The plant used mainly chrysotile, with smaller amounts of crocidolite and amosite. The workers were compared with a local reference cohort of 1233 industrial workers. Their estimated median cumulative exposure was 2.3 fibre-years/ml. The main comparison counted only men at least 20 years past their start of employment, in both cohorts. On that basis, 13 of 592 deaths among the asbestos cement workers were from pleural mesothelioma, against one of 279 referent deaths. No peritoneal mesothelioma was found. In a nested case-referent analysis, each fibre-year/ml received 40 or more years before diagnosis carried a relative risk of 1.9. Duration of exposure showed no relation once latency was considered. Deaths from non-malignant respiratory disease were significantly raised (relative risk 2.6). Respiratory cancer excluding mesothelioma did not differ significantly between the cohorts. Gastrointestinal cancer overall was not significantly increased (relative risk 1.2, 95% confidence interval 0.7 to 2.0). Colorectal cancer deaths rose with cumulative dose, by an estimated 1.6% per fibre-year/ml (confidence interval 0.2 to 3.1%). The authors suggested the colorectal excess might reflect cement exposure. They noted incomplete work histories and no dust measurements before 1956.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective cohort study comparing asbestos cement workers with a local referent cohort of industrial workers not exposed to asbestos cement, plus a nested case-referent study of mesothelioma cases
• Who was studied: Male employees of an asbestos cement plant in the south of Sweden who were employed at least three months between 1907 and 1977 (2898 persons). Immigrant workers were excluded from the cohort analysis, leaving 1929 Swedish workers, with vital status followed to 31 December 1986. The referents were 1233 Swedish men from five regional industries not known to have processed asbestos. A minimum latency of 20 years since start of employment was applied in both cohorts.
• Exposure: Asbestos cement manufacture (sheets, shingles, ventilation pipes, hand moulded details). The asbestos was mainly chrysotile (more than 95%), with smaller amounts of crocidolite and amosite. Estimated median cumulative exposure was 2.3 f-years/ml, and median exposure intensity was 1.2 f/ml.
• Main results:
  • With a minimum latency of 20 years since start of employment in both cohorts, the exposed cohort had 13 pleural mesotheliomas among a total of 592 deaths. The referents had one pleural mesothelioma (a sugar refinery worker) among 279 deaths. Table 2 gives a relative risk of 7.2 (95% CI 0.97 to 54).
  • No case of peritoneal mesothelioma was found.
  • Pleural mesothelioma mortality compared with referents, by cumulative dose: less than 15 f-years/ml, RR 1.9 (95% CI 0.2 to 21.3); 15 to 39 f-years/ml, RR 21.2 (2.5 to 178); 40 or more f-years/ml, RR 22.8 (2.4 to 212).
  • In the nested case-referent study, there was a significant dose response relation for cumulative exposure 40 years or more before diagnosis, with a multiplicative relative risk of 1.9 for each f-year/ml. No relation was found with duration of exposure when latency was accounted for.
  • Non-malignant respiratory disease caused 56 deaths in the exposed cohort and 13 in the referents. The relative risk was 2.6, described as a significant overrisk.
  • All-cause mortality was 592 deaths in the exposed cohort and 279 in the referents, relative risk 1.2 (95% CI 1.01 to 1.4). Mortality from all malignancies was also significantly increased, relative risk 1.6 (95% CI 1.2 to 2.1).
  • For respiratory cancers other than mesothelioma (35 exposed versus 10 referent deaths, relative risk 1.8), death rates did not differ significantly between the cohorts, though the ratio was close to two.
  • Gastrointestinal cancer mortality overall was not significantly increased in the exposed cohort: 49 versus 22 deaths, relative risk 1.2 (95% CI 0.7 to 2.0).
  • Heart disease (coronary and unspecified) mortality was not increased: 219 versus 112 deaths, relative risk 1.1.
  • Colorectal cancer mortality showed no relation with duration of employment. It did show a significant dose response relation with cumulative exposure: an estimated 1.6% (95% CI 0.2 to 3.1) increase per f-year/ml. The relative risk in the 40 or more f-years/ml group was 3.4 (95% CI 1.2 to 9.5).
• The authors' conclusion: The authors suggested that the overrisk of colorectal cancer in highly exposed workers might be due to cement exposure.
• Limitations the authors state:
  • Exposure assessment was difficult because work histories were incomplete, particle counts had to be converted to fibre counts, and there were no dust measurements for 1907 to 1955.
  • Work histories could not be obtained for 22% of the workers.
  • Before 1942, real exposure may have been greatly underestimated for some tasks.
  • The low median cumulative exposure gave low statistical power for effects of high exposure.
  • No dose response pattern was found for the increased overall mortality, so the authors said this result must be interpreted with caution.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Cumulative Exposure, Chrysotile, Pleural Mesothelioma, Latency, Peritoneal Mesothelioma, Relative Risk, Mesothelioma.

Related studies

• Mortality and cancer morbidity in a cohort of Canadian petroleum workers — R.J. Lewis, A.R. Schnatter, et al. (2003)
• A cohort study on mortality among wives of workers in the asbestos cement industry in Casale Monferrato, Italy — C. Magnani, B. Terracini, et al. (1993)
• Mortality in a cohort of cement workers in a plant of Central Italy — F. Giordano, V. Dell'orco, et al. (2012)
• A case-referent study of cancer mortality among sulfate mill workers in Sweden — E. Andersson, S. Hagberg, et al. (2001)
• Survival in cohorts of asbestos cement workers and controls — M. Albin, V. Horstmann, et al. (1996)
• Cumulative asbestos exposure and mortality from asbestos related diseases in a pooled analysis of 21 asbestos cement cohorts in Italy — F. Luberto, D. Ferrante, et al. (2019)

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