Cancer in ex-asbestos cement workers in Israel, 1953-1992

Our plain-English summary of Cancer in ex-asbestos cement workers in Israel, 1953-1992, by T.H. Tulchinsky, G.M. Ginsberg, J. Iscovich, et al (American Journal of Industrial Medicine, 1999).

The study

• Authors: T.H. Tulchinsky, G.M. Ginsberg, J. Iscovich, S. Shihab, A. Fischbein, E.D. Richter
• Journal: American Journal of Industrial Medicine
• Published: 1999;35(1):1-8
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A cohort of 3,057 male workers employed in an asbestos-cement plant using 90% chrysotile-10% crocidolite, located in Northern Israel, was followed from 1953-1992 for incidence and mortality from cancer. In the years 1978-1992, the cohort had an elevated risk for all malignant neoplasms combined (n = 153, SIR = 117, ns), lung cancer (n = 28, SIR = 135, ns), mesothelioma (n = 21; SIR > 5000, p < .0001), unspecified pleural cancer (n = 5; SIR = 278, P < .0001), and liver cancer (n = 7, SIR 290, ns). Risks for colo-rectal (n = 19; SIR = 79, ns), bladder (n = 12, SIR 69) and renal cancers (n = 5, SIR 104) were less than expected. Risk for mesothelioma showed a sharp risk gradient with duration of exposure, increasing from 1 per 625 for those employed less than 2 years to 1 per 4.5 workers employed over 30 years. The ratio of mesothelioma to excess lung cancer cases was 2.9 to 1, or 3.6 to 1, if pleural cases of unspecified origin were included; the pleura to peritoneum ratio of verified mesothelioma cases was 20 to 1. This atypically high ratio of mesothelioma to excess lung cancer cases is suggested to be the combined result of high past asbestos exposures in the workers and their low prior risk for lung cancer, and possibly, relatively early smoking cessation in relation to asbestos exposure.

In plain English

This retrospective cohort study followed 3,057 Jewish male former asbestos-cement workers in Northern Israel from 1953 to 1992. The plant used 90% chrysotile and 10% crocidolite. Cancers in 1978–1992 were compared with national Jewish male rates. There were 21 histologically confirmed mesotheliomas against 0.37 expected (standardized incidence ratio, SIR, 5,676; 95% CI 3,242 to 8,088), 20 pleural for every 1 peritoneal. Lung cancer was raised but not statistically significantly (28 cases against 20.7 expected; SIR 135, 95% CI 85 to 185). Mesothelioma risk rose with years employed: 1 in 625 workers employed two years or less, 1 in 4.5 employed over 30 years. Workers employed 20 or more years, versus under 20, had odds ratios of 4.6 (95% CI 1.9 to 11.1) for lung cancer and 11.3 (95% CI 3.9 to 32.3) for mesothelioma. The ratio of mesothelioma to excess lung cancer was 3 to 1. The authors suggested the high ratio reflected high past exposures, low background lung cancer in Israeli men and possibly early smoking cessation. They lacked data on smoking trends among these workers, so could not assess that last explanation.

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 cancer incidence in former workers with national rates (standardized incidence ratios), with logistic regression on duration of exposure
• Who was studied: 3,057 Jewish male former workers of an asbestos-cement plant in the Acco sub-district, Western Galilee, Northern Israel, followed 1953–1992. Expected rates were calculated for 1978–1992. Women office workers (632) and non-Jewish male workers (502) were excluded.
• Exposure: Asbestos-cement production using 90% chrysotile and 10% crocidolite. Measured levels in the 1960s and 1970s were 1.5 to 14.0 fibers/cc in storage areas and 0.3 to 40.0 fibers/cc in processing and molding areas. Average employment was 3.4 years, and 43.1% of the cohort worked less than one year.
• Main results:
  • All cancers combined, cohort 1978–1992: 153 observed vs 130.6 expected, SIR 117 (95% CI 99–136), not statistically significant
  • Lung cancer, cohort 1978–1992: 28 observed vs 20.7 expected, SIR 135 (95% CI 85–185), not statistically significant. 34 lung cancer cases were identified in total, 6 of them before 1978.
  • The lung cancer SIR fell over time: 266 in 1978–1981, 251 in 1982–1985, 79 (95% CI 10, 148) in 1986–1989, and 17 (95% CI 0, 51) in 1990–1992
  • Of 32 suspected mesothelioma cases in 1978–1992, 6 were excluded on review. Of the remaining 26, 21 were confirmed by tissue pathology, with a pleural to peritoneal ratio of 20 to 1.
  • Mesothelioma, cohort 1978–1992: 21 observed vs 0.37 expected, SIR 5,676 (95% CI 3,242–8,088)
  • Mesothelioma by duration of employment: 1 in 625 workers employed two years or less, 1 in 10 employed 25–30 years, and 1 in 4.5 employed over 30 years
  • Workers employed 20 or more years compared with those employed less than 20 years: risk odds ratio 4.6 (95% CI 1.9–11.1) for lung cancer and 11.3 (95% CI 3.9–32.3) for mesothelioma. Age and year of starting employment were non-significant covariates.
  • Ratio of mesothelioma to excess lung cancer, 1960–1992: 3 to 1 (21 mesotheliomas to 7 excess lung cancers). Table III gives this ratio as 2.88.
  • Primary liver cancer in the cohort: 7 observed vs 2.4 expected, SIR 294 (95% CI 76–511). The authors called this an increased risk, while the abstract marks it not statistically significant.
  • Bladder cancer in the cohort was lower than expected: 12 observed vs 18.4 expected, SIR 65 (95% CI 28–102), described in the results as significantly lower
  • Colorectal cancer in the cohort was lower than expected but not significantly: 19 observed vs 24.1 expected, SIR 79 (95% CI 43–115)
  • Average annual mesothelioma rate among Jewish males in the Acco district, 1981–1992: 12.1 per million, compared with 2.1 per million in the adjacent Northern Districts
• The authors' conclusion: The authors concluded that the high ratio of mesothelioma to excess lung cancer was suggested to result from high past exposures, a low background lung cancer risk among Israeli males, and possibly relatively early smoking cessation. They also stated that exposure to this mix of predominantly chrysotile asbestos produced increased cancer risk.
• Limitations the authors state:
  • No data on trends in smoking among the workers, so the authors could not assess the influence of smoking changes on lung cancer or on the mesothelioma to lung cancer ratio
  • Some lung cancer cases may have been under-reported or misclassified as undefined pleural cancer
  • Some or all of the unconfirmed pleural cancer cases could have been mesotheliomas
  • Duration of exposure was uncertain for 588 cohort members
  • Relatives of workers and people exposed outside the factory were not included
  • Longer follow-up is needed to see whether the lower than expected colorectal cancer risk persists

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Chrysotile, Crocidolite, Neoplasm, Lung Cancer, Mesothelioma, Pleura, Peritoneum.

Related studies

• Malignant mesothelioma in Israel, 1961-1992 — J. Iscovich, A. Fischbein, et al. (1999)
• Epidemiology of mesothelioma in Israel — C. Lemesch, R. Steinitz, et al. (1976)
• Incidence of lung cancer by histological type among asbestos cement workers in Denmark — E. Raffn, E. Lynge, et al. (1993)
• Lung cancer in asbestos cement workers in Denmark — E. Raffn, E. Villadsen, et al. (1996)
• Colorectal cancer in asbestos cement workers in Denmark — E. Raffn, E. Villadsen, et al. (1996)
• Genetic polymorphism for glutathione-S-transferase mu in asbestos cement workers — K. Jakobsson, A. Rannug, et al. (1994)

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