Malignant mesothelioma and asbestos exposure among auto mechanics: appraisal of scientific evidence

Our plain-English summary of Malignant mesothelioma and asbestos exposure among auto mechanics: appraisal of scientific evidence, by O. Wong (Regulatory Toxicology and Pharmacology, 2001).

The study

• Author: O. Wong
• Journal: Regulatory Toxicology and Pharmacology
• Published: 2001;34(2):170-7
• Type of article: Review
• Cited by: 46 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In 1986 the U.S. Environmental Protection Agency (EPA) issued an official guideline on the prevention of asbestos disease among auto mechanics. In the EPA guideline, malignant mesothelioma was listed as a consequence of exposure to asbestos fibers from brake linings and clutch facings among auto mechanics. EPA formulated its 1986 opinion by relying solely on a few outdated case reports and not on epidemiologic studies. A review of the literature indicates that there are six epidemiologic studies providing relevant information on malignant mesothelioma among auto mechanics. Three of the six studies had already been published by 1986, the year in which EPA issued its guideline. The results of the six studies were remarkably consistent in that all six studies reported no increased risk of malignant mesothelioma among auto mechanics. The relative risks reported in the six studies ranged from 0.62 to 1.00. Based on a meta-analysis of the combined data of all six studies consisting of approximately 1500 malignant mesothelioma cases, the mesothelioma relative risk for auto mechanics is 0.90 (95% confidence interval 0.66-1.23). An application of Hill's causation criteria to epidemiologic data of malignant mesothelioma among auto mechanics clearly demonstrates that auto mechanics do not have an increased risk of malignant mesothelioma as a result of exposure to asbestos fibers from brake linings and clutch facings. However, in spite of the scientific evidence, EPA has not modified or revised its 1986 guideline. Occupational regulatory policies and guidelines, when based on proper scientific evidence, are invaluable and can prevent avoidable diseases in workers or other exposed individuals in the general public. On the other hand, it is the regulators' responsibility to develop, modify, and revise policies and guidelines in accordance with the most relevant and the latest scientific data. In this instance EPA as a regulator has not fulfilled its responsibility of providing the most accurate and up-to-date information to the workers or the general public.

Copyright 2001 Academic Press.

In plain English

This article reviewed, with a meta-analysis, published case-control studies of malignant mesothelioma among auto mechanics. It criticized a 1986 U.S. Environmental Protection Agency (EPA) guideline on asbestos disease among auto mechanics. The author identified six such studies, published 1980 to 2000, from North America, Germany and Spain. Their relative risks for auto or vehicle mechanics ranged from 0.62 to 1.00; the author calculated the Spanish figure from that study's published numbers. Combining all six studies, about 1500 mesothelioma cases, with larger studies weighted more, gave a summary relative risk of 0.90 (95% confidence interval 0.66 to 1.23). Brake-work results were: 1.0 (95% confidence interval 0.6 to 1.6) for workers doing brake lining installation and repair in a U.S. National Cancer Institute study, 0.76 (0.28 to 2.05) for German mechanics definitely doing brake service, and 0.3 (0 to 1.4) for British Columbia mechanics doing brake lining installation or repair. The author noted that some individual studies were small. Applying Hill's causation criteria, the author concluded that auto mechanics do not have an increased risk of malignant mesothelioma from asbestos in brake linings and clutch facings.

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: Review and meta-analysis of six published case-control studies, presented as a critique of the 1986 EPA guideline
• Who was studied: Six case-control studies of malignant mesothelioma, published 1980 to 2000, from Canada and the United States, Connecticut, New York State and Los Angeles County, Germany, British Columbia and Spain; about 1500 mesothelioma cases in total
• Exposure: Asbestos fibers from brake linings and clutch facings in auto mechanics' work; the author stated that the asbestos in brake linings is entirely chrysotile
• Main results:
  • Relative risks of mesothelioma for auto or vehicle mechanics in the six individual studies ranged from 0.62 to 1.00
  • Meta-analysis of all six studies: summary relative risk for auto mechanics 0.90 (95% CI 0.66 to 1.23)
  • The meta-analysis weighted studies by the inverse of the variance of their risk estimates, so larger studies received more weight
  • For the Spanish study, which did not publish a risk estimate for vehicle mechanics (3 cases, 14 controls), the author estimated a relative risk of 0.62 (95% CI 0.17 to 2.25)
  • U.S. National Cancer Institute study (Spirtas et al., 1985): relative risk for workers engaged in brake lining installation and repair 1.0 (95% CI 0.6 to 1.6)
  • German study (Woitowitz and Rödelsperger, 1994): relative risk for motor vehicle mechanics definitely engaged in brake service 0.76 (95% CI 0.28 to 2.05)
  • British Columbia study (Teschke et al., 1997): relative risk for mechanics specifically involved in brake lining installation or repair 0.3 (95% CI 0 to 1.4)
• The authors' conclusion: The author concluded that applying Hill's causation criteria to the epidemiologic data showed that auto mechanics do not have an increased risk of malignant mesothelioma from exposure to asbestos fibers from brake linings and clutch facings
• Limitations the authors state:
  • Some of the individual studies were relatively small, so their risk estimates were imprecise (wide confidence intervals)

Topics

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

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Asbestos Exposure, Brake Lining, Relative Risk, Meta-Analysis, Mesothelioma, confidence interval, Causation.

Related studies

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• Abdominal pain and bloating in an auto mechanic — L. Neshatian, M. Halland, et al. (2014)
• Mesothelioma in vehicle mechanics: is the risk different for Australians? — M.A. Kelsh, V.A. Craven, et al. (2007)
• Egilman's assessment regarding exposures of auto mechanics to amphiboles is not accurate — D.J. Paustenbach, K.R. White (2012)
• Lung cancer and mesothelioma among male automobile mechanics: a review — F. Laden, M.J. Stampfer, et al. (2004)
• Mesothelioma among brake mechanics: an expanded analysis of a case-control study — P.A. Hessel, M.J. Teta, et al. (2004)

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