Asbestos fibres in the lungs of an American mechanic who drilled, riveted, and ground brake linings: a case report and discussion

Our plain-English summary of Asbestos fibres in the lungs of an American mechanic who drilled, riveted, and ground brake linings: a case report and discussion, by M.M. Finkelstein (The Annals of Occupational Hygiene, 2015).

The study

• Author: M.M. Finkelstein
• Journal: The Annals of Occupational Hygiene
• Published: 2015;59(4):525-7
• Type of article: Case report, Letter
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

In North America and Europe, the use of asbestos in friction products was discontinued before the end of the 20th century. In the developing world, the use of asbestos-containing friction products continues. In 2010, Cely-Garcia and colleagues (Cely-Garcia et al., 2012) sampled three brake repair shops located in Bogota, Colombia. Both asbestos and non-asbestos containing brake linings were sold separately or attached to a shoe. When brake linings are sold separated from the shoe, they must be manipulated to attach them to the shoe before installation. The process starts with the removal of the old brake shoe from the vehicle's brake drum. If the existing brake shoe is to be reused, the old lining needs to be removed and the old shoe must be ground to prepare it for a new lining. Riveting requires drilling holes in the linings and shoes and before installing rivets, the lining must be countersunk. The borders of the lining are bevelled. On some occasions, the entire exposed surface of the lining is ground to make it thinner. Once attached to the shoe, the edges of brake linings may extend beyond the shoe. In this case, it is necessary to cut or grind the edges to match the lining to the shoe before bevelling or grinding. The authors reported that 'the sampling results indicate that the brake mechanics sampled are exposed to extremely high asbestos concentrations (i.e. based on transmission electron microscopy counts), suggesting that this occupational group could be at excess risk of asbestos-related diseases'.

© The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

In plain English

This letter to the editor reported the case of one American man, Mr. X, who ran a garage from 1979 until 1989. He replaced brakes using a stock of Bendix linings. He drilled out old rivets, riveted new linings to the shoes and ground them, and compressed air was used. Three or four replacements were done daily, and he had no other asbestos exposures. The author stated that Bendix linings were made from Canadian chrysotile asbestos contaminated with amphiboles including tremolite. Mr. X was diagnosed with pleural mesothelioma in 2010, which was confirmed at autopsy. His lung tissue contained 2540 uncoated fibres per gram of wet tissue. Of six fibres counted, three were tremolite and three were not asbestos, and chrysotile was not detected. His tremolite level was 6.6-fold higher (95% confidence interval 1.5–23) than the average in 18 unexposed control subjects from the same laboratory. The author concluded that inhaling and retaining asbestos fibres places mechanics working with friction products at increased risk of asbestos-related diseases. The author disclosed consulting for plaintiffs' lawyers in asbestos litigation. The fibre analysis was requested by the manufacturer's attorneys.

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: Case report of a single person, published as a letter to the editor, with discussion
• Who was studied: One American service station owner (Mr. X), a former bank executive. He operated a full-service garage from 1979 until the family sold it in 1989. He was diagnosed with pleural mesothelioma in 2010, and the final diagnosis at autopsy was malignant pleural mesothelioma, biphasic variant.
• Exposure: Brake work with Bendix brake linings: drilling out old rivets, peeling off old linings, drilling and riveting new linings to the shoe, and grinding them, with compressed air used. Three or four brake replacements were done daily, and he had no other asbestos exposures. The author stated that Bendix linings were made from Canadian asbestos, a chrysotile asbestos contaminated with amphiboles including tremolite.
• Main results:
  • Scanning electron microscopy of Mr. X's autopsy lung tissue found 2540 uncoated fibres per gram of wet lung tissue.
  • Six uncoated fibres were counted in 100 microscope fields. Three were tremolite and three were not asbestos (silica, rutile, and stainless steel).
  • The single asbestos body core examined in Mr. X's lung tissue was identified as tremolite.
  • Mr. X's tremolite fibre burden was 6.6-fold higher (95% confidence interval 1.5–23) than the mean tremolite fibre burden among 18 control subjects from the same laboratory (exact Poisson regression).
  • Chrysotile fibres were not detected in Mr. X's lung tissue. The author attributed this to chrysotile being cleared from lung tissue.
• The authors' conclusion: The author concluded that inhalation and retention of asbestos fibres places mechanics working with friction products at increased risk of asbestos-related diseases. The author also said that authorities in countries still using asbestos-containing friction products should consider mandating asbestos-free alternatives.

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: Brake Lining, Friction Products, Transmission Electron Microscopy (TEM).

Related studies

• The analysis of asbestos count data with "nondetects": the example of asbestos fiber concentrations in the lungs of brake workers — M.M. Finkelstein (2013)
• Asbestos exposure during brake lining maintenance and repair — A.N. Rohl, A.M. Langer, et al. (1976)
• Environmental and occupational health hazards associated with the presence of asbestos in brake linings and pads (1900 to present): a "state-of-the-art" review — D.J. Paustenbach, B.L. Finley, et al. (2004)
• Environmental and occupational health hazards associated with the presence of asbestos in brake linings and pads (1900 to present): A "state-of-the-art" review — S.S. Paskal (2004)
• Evaluation of the size and type of free particulates collected from unused asbestos-containing brake components as related to potential for respirability — M.A. Atkinson, M. O'sullivan, et al. (2004)
• Re: Evaluation of the size and type of free particulates collected from unused asbestos-containing brake components as related to potential for respirability — D.J. Paustenbach, B.L. Finley, et al. (2006)

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