Asbestos-related diseases in automobile mechanics

Our plain-English summary of Asbestos-related diseases in automobile mechanics, by J. Ameille, N. Rosenberg, M. Matrat, et al (The Annals of Occupational Hygiene, 2012).

The study

• Authors: J. Ameille, N. Rosenberg, M. Matrat, A. Descatha, D. Mompoint, L. Hamzi, C. Atassi, M. Vasile, R. Garnier, J.C. Pairon
• Journal: The Annals of Occupational Hygiene
• Published: 2012;56(1):55-60
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Purpose: Automobile mechanics have been exposed to asbestos in the past, mainly due to the presence of chrysotile asbestos in brakes and clutches. Despite the large number of automobile mechanics, little is known about the non-malignant respiratory diseases observed in this population. The aim of this retrospective multicenter study was to analyse the frequency of pleural and parenchymal abnormalities on high-resolution computed tomography (HRCT) in a population of automobile mechanics.

Methods: The study population consisted of 103 automobile mechanics with no other source of occupational exposure to asbestos, referred to three occupational health departments in the Paris area for systematic screening of asbestos-related diseases. All subjects were examined by HRCT and all images were reviewed separately by two independent readers; who in the case of disagreement discussed until they reached agreement. Multiple logistic regression models were constructed to investigate factors associated with pleural plaques.

Results: Pleural plaques were observed in five cases (4.9%) and interstitial abnormalities consistent with asbestosis were observed in one case. After adjustment for age, smoking status, and a history of non-asbestos-related respiratory diseases, multiple logistic regression models showed a significant association between the duration of exposure to asbestos and pleural plaques.

Conclusions: The asbestos exposure experienced by automobile mechanics may lead to pleural plaques. The low prevalence of non-malignant asbestos-related diseases, using a very sensitive diagnostic tool, is in favor of a low cumulative exposure to asbestos in this population of workers.

In plain English

This retrospective study, run at three occupational health departments in the Paris area, reviewed high-resolution CT chest scans of 103 male automobile mechanics. They had been referred between January 2002 and June 2009 for routine screening for asbestos-related disease. Their only known occupational asbestos exposure was their mechanic work, and the authors note that brakes and clutches once contained chrysotile asbestos. Exposure before France's 1997 asbestos ban lasted 22.6 years on average. Pleural plaques were found in five men (4.9%), diffuse pleural thickening in four, nonspecific pleural thickening in nine, and lung changes consistent with asbestosis in one. No lung cancer or pleural mesothelioma was detected. After adjustment for age, smoking and past respiratory disease, longer exposure was significantly associated with pleural plaques (adjusted odds ratio 1.2 per year of exposure, 95% confidence interval 1.0 to 1.4, P = 0.048). The authors concluded that this exposure may lead to pleural plaques and that the low prevalence suggests low cumulative exposure. As limitations they named the small sample, the lack of an unexposed comparison group, and the lack of objective exposure measurement.

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 multicenter study (cross-sectional review of HRCT screening scans)
• Who was studied: 103 male automobile mechanics with no other source of occupational asbestos exposure, referred between 1 January 2002 and 30 June 2009 to occupational health departments in Garches, Créteil and Paris (Fernand Widal), France. Of 242 referred mechanics, 89 with other possible asbestos exposure and 50 without an available HRCT were excluded. Mean age was 54.4 years.
• Exposure: Asbestos exposure from work as an automobile mechanic. The authors attribute past exposure mainly to chrysotile asbestos in brakes and clutches. Mean duration of exposure (counting only work before the 1997 French ban) was 22.6 years, range 4 to 45 years. 83.5% used compressed air for brake cleaning, and some repaired truck brakes.
• Main results:
  • Among the 103 mechanics, pleural plaques were found in five (4.9%).
  • Four mechanics had diffuse pleural thickening and nine had nonspecific pleural thickening.
  • One mechanic had interstitial (lung tissue) abnormalities consistent with asbestosis. He had worked 24 years as an automobile mechanic doing brake repairs on trucks for more than 8 hours a week.
  • No case of lung cancer or pleural mesothelioma was detected among the 103 mechanics.
  • Mechanics with pleural plaques (n = 5) had a longer mean duration of exposure than those without (n = 98): 31.0 years versus 22.2 years, P = 0.01. They also had a longer mean latency: 42.2 years versus 36.6 years, P = 0.047.
  • In the regression model adjusted for age, previous respiratory disease and smoking, duration of exposure (in years) was associated with pleural plaques: adjusted odds ratio 1.2 (95% CI 1.0 to 1.4), P = 0.048. In the separate model, latency was not significant: adjusted odds ratio 1.1 (0.9 to 1.4).
• The authors' conclusion: The authors concluded that the asbestos exposure experienced by French car mechanics may lead to pleural plaques. They also concluded that the low prevalence of non-malignant asbestos-related disease, despite the use of sensitive HRCT, favors low cumulative asbestos exposure in this population.
• Limitations the authors state:
  • Relatively small number of subjects, no unexposed control group, and no objective assessment of the level of occupational asbestos exposure.
  • It is questionable how representative the study sample is.

Topics

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

Medical terms in this study, explained in our Lexicon: Chrysotile, High-Resolution CT (HRCT), Occupational Exposure, Pleural Plaques, Interstitial, Asbestos Exposure, Cumulative Exposure.

Related studies

• Cumulative asbestos exposure for US automobile mechanics involved in brake repair (circa 1950s-2000) — B.L. Finley, R.O. Richter, et al. (2007)
• Lung cancer and mesothelioma among male automobile mechanics: a review — F. Laden, M.J. Stampfer, et al. (2004)
• Chrysotile asbestos exposure associated with removal of automobile exhaust systems (ca. 1945-1975) by mechanics: results of a simulation study — D.J. Paustenbach, A.K. Madl, et al. (2006)
• Asbestos exposure and benign asbestos diseases in 772 formerly exposed workers: dose-response relationships — G. Mastrangelo, M.N. Ballarin, et al. (2009)
• Asbestos-related pleural diseases: dimensional criteria are not appropriate to differentiate diffuse pleural thickening from pleural plaques — J. Ameille, M. Matrat, et al. (2004)
• Asbestos related diseases from environmental exposure to crocidolite in Da-yao, China. I. Review of exposure and epidemiological data — S. Luo, X. Liu, et al. (2003)

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