Brake mechanics, asbestos, and disease risk

Our plain-English summary of Brake mechanics, asbestos, and disease risk, by M. Huncharek (The American Journal of Forensic Medicine and Pathology, 1990).

The study

• Author: M. Huncharek
• Journal: The American Journal of Forensic Medicine and Pathology
• Published: 1990;11(3):236-40
• Type of article: Review
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004905).

Abstract

Health risks posed by inhalable asbestos fibers are known to exist in a variety of industrial and nonindustrial settings. Although early studies described an increased risk of asbestosis, lung cancer, and mesothelioma in asbestos-industry workers, subsequent research revealed the existence of a potential asbestos-related health hazard in nonasbestos industries such as the textile and railroad industries. Brake mechanics and garage workers constitute a large work force with potential exposures to levels of asbestos capable of producing disease. Unfortunately, the health risk faced by these workers has received little attention. This article briefly discusses currently available information on the asbestos health risks of workers in this setting, and highlights the need for further investigations of this occupational group.

In plain English

This article was a short narrative review by a single author, not a new study. It discussed published information on asbestos exposure and disease risk among automobile brake mechanics and garage workers. It also discussed the debate over whether chrysotile causes mesothelioma; the article says chrysotile is the fiber most widely used in US brake linings. The review covered air-sampling studies from the United States, England and West Germany, case reports of mesothelioma in brake workers, and population studies. In one of these, a New York study of volunteer brake workers, fiber levels at 3 to 5 feet while dust was blown from brake drums averaged 15.9 fibers/ml. A Swedish study recorded 39 lung cancer deaths among car mechanics where 23 were expected (p less than 0.01), and found one mesothelioma case. The author noted that much of the evidence came from case reports or small numbers of cases. The author concluded that automobile mechanics may be at increased risk of asbestos-related diseases, that this risk had not been extensively studied, and that the cancer risk from chrysotile in brake and clutch work was poorly defined.

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: narrative review of published literature (single author)
• Who was studied: automobile brake mechanics and garage workers, mainly in the United States (estimated at about 900,000 US auto mechanics and garage workers), as described in previously published studies
• Exposure: asbestos (mainly chrysotile) in automobile brake linings, brake shoes and clutch pads, including dust released when brake drums were cleaned with compressed air
• Main results:
  • In a 1976 Mount Sinai study of brake-repair workers (Lorimer et al.) cited by the review, personal samples taken at 3 to 5 ft while dust was blown from brake drums showed 6.6 to 29.4 fibers/ml, with a mean of 15.9 fibers/ml
  • In the same cited Mount Sinai study, over one-fourth of 104 men examined had chest X-ray abnormalities described as consistent with asbestosis. An additional one-fourth had lung function results indicating restrictive lung disease. The subjects were volunteers.
  • An earlier English study cited by the review found relatively low airborne levels during brake maintenance, below 2 fibers per cubic centimeter
  • A 1986 West German field study of 76 service stations cited by the review found low fiber concentrations, typically 0.1 × 10⁶ fibers per cubic meter
  • In a Swedish study of car mechanics cited by the review (1961 to 1973), 741 deaths occurred versus 776 expected, and 187 cancer deaths versus 154 expected (described as statistically significant). There were 39 lung cancer deaths versus 23 expected (p less than 0.01), and only one mesothelioma case was found.
  • A 1980 North American study of malignant mesothelioma (McDonald and McDonald) cited by the review noted no excess risk among garage workers
  • In a cited 1982 case report of mesothelioma in a 55-year-old brake-repair worker, lung tissue analysis found chrysotile fibers and no amphibole fibers. The review also described a case of pleural mesothelioma in a 47-year-old automobile mechanic whose only known exposure was clutch and brake repair work over 11 years.
• The authors' conclusion: The author concluded that automobile mechanics may be at increased risk for asbestos-related diseases, that this risk had not been extensively studied, and that better exposure estimates and further investigation were needed to define the risk
• Limitations the authors state:
  • The author stated that much of the information on garage workers' health risks came from case reports or reviews of small numbers of cases
  • The author stated that epidemiological studies of this workforce were hampered by the difficulty of tracing a large, nonunionized group of workers
  • The author noted that subjects in the Mount Sinai study were volunteers, which introduced considerable selection bias, so its findings should be interpreted cautiously
  • The author noted that in the Swedish study, cigarette smoking and other exposures such as automobile exhaust may have played a role in the lung cancer findings
  • The author stated that it is unclear how accurate an estimate of 20,000 future asbestos-related cancer deaths among US automobile-maintenance workers will prove to be

Topics

The National Library of Medicine indexes this study under subjects our site covers: Auto mechanics and brake work, Chrysotile.

Medical terms in this study, explained in our Lexicon: Lung Cancer, Mesothelioma.

Related studies

• Pleural mesothelioma in a brake mechanic — M. Huncharek, J. Muscat, et al. (1989)
• Cumulative asbestos exposure for US automobile mechanics involved in brake repair (circa 1950s-2000) — B.L. Finley, R.O. Richter, et al. (2007)
• An evaluation of short-term exposures of brake mechanics to asbestos during automotive and truck brake cleaning and machining activities — R.O. Richter, B.L. Finley, et al. (2009)
• The hazards of asbestos for brake mechanics — B. Castleman, L.A. Camarota, et al. (1975)
• Asbestos in brakes: exposure and risk of disease — R.A. Lemen (2004)
• RE: Asbestos in brakes: exposure and risk of disease — M.J. Teta (2004)

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