Personal exposure to asbestos and respiratory health of heavy vehicle brake mechanics

Our plain-English summary of Personal exposure to asbestos and respiratory health of heavy vehicle brake mechanics, by M.F. Cely-García, C.A. Torres-Duque, M. Durán, et al (Journal of Exposure Science & Environmental Epidemiology, 2015).

The study

• Authors: M.F. Cely-García, C.A. Torres-Duque, M. Durán, P. Parada, O.L. Sarmiento, P.N. Breysse, J.P. Ramos-Bonilla
• Journal: Journal of Exposure Science & Environmental Epidemiology
• Published: 2015;25(1):26-36
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos brake linings and blocks are currently used in heavy vehicle brake repair shops (BRSs) in Bogotá, Colombia. Some brake products are sold detached from their supports and without holes, requiring manipulation before installation. The aim of this study was to assess asbestos exposures and conduct a preliminary evaluation of respiratory health in workers of heavy vehicles in BRSs. To estimate asbestos exposures, personal and area samples were collected in two heavy vehicle BRSs. Each shop was sampled during six consecutive days for the entire work shift. Personal samples were collected on 10 workers including riveters, brake mechanics, and administrative staff. Among workers sampled, riveters had the highest phase contrast microscopy equivalent (PCME) asbestos concentrations, with 8-h time-weighted average (TWA) personal exposures ranging between 0.003 and 0.157 f/cm(3). Respiratory health evaluations were performed on the 10 workers sampled. Three workers (30%) had circumscribed pleural thickening (pleural plaques), with calcifications in two of them. This finding is strongly suggestive of asbestos exposure. The results of this study provide preliminary evidence that workers in heavy vehicle BRSs could be at excessive risk of developing asbestos-related diseases.

In plain English

This study measured airborne asbestos and examined the lungs of 10 workers at two heavy vehicle brake repair shops in Bogotá, Colombia, in 2012. Each shop was sampled for six consecutive days, yielding 235 air samples. Chrysotile was the only type of asbestos found. Riveters, who drill, countersink and rivet brake linings and blocks, had the highest exposures. Their 8-hour average exposures ranged from 0.003 to 0.157 fibers per cubic centimeter. One riveter exceeded both the US OSHA and the Colombian limits on 5 of the 6 days sampled. The other riveters and all non-riveter workers stayed within both limits; the highest non-riveter 8-hour average was 0.017. All chest X-rays were normal. CT scans showed pleural calcifications in three workers, two of whom also had plaques. All three were current or former riveters and had negative tuberculin skin tests, which the authors said do not completely rule out tuberculosis. No asbestos-related disease was diagnosed. The authors noted the small sample and lack of a control group. They concluded the findings were preliminary evidence that these workers could be at excessive risk of asbestos-related diseases.

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: Exploratory study combining personal and area air sampling for asbestos with a preliminary respiratory health evaluation (clinical exam, lung function tests, chest X-ray, CT scan, tuberculin skin test); shops and workers selected by convenience; no control group
• Who was studied: 10 workers (4 riveters, plus a brake mechanic, secretaries, a warehouseman and shop owners; 8 men and 2 women, mean age 40) at two heavy vehicle brake repair shops in Bogotá, Colombia, sampled in January and February 2012
• Exposure: Chrysotile asbestos released during manipulation (unriveting, drilling, countersinking, riveting, beveling, grinding, cutting) and cleaning of asbestos-containing heavy vehicle brake linings and blocks; chrysotile was the only asbestos type identified
• Main results:
  • 235 air samples were collected over the 12 sampling days
  • Riveters had the highest exposures, with 8-hour time-weighted average personal exposures (phase contrast microscopy equivalent) ranging from 0.003 to 0.157 f/cm3
  • Riveter 1 exceeded the US OSHA limit and the Colombian standard on 5 of the 6 days sampled
  • All other riveters were within both the Colombian and US OSHA standards. Riveter 4 was within the standard but above the US OSHA action level of 0.05 f/cm3 on 3 of 6 days, with a highest 8-hour average of 0.084 f/cm3.
  • Non-riveter workers were within the standards; their highest 8-hour average was 0.017 f/cm3
  • All riveters' short-term (30-minute) exposures were within the US OSHA short-term limit of 1 f/cm3. Some 30-minute samples measured by electron microscopy (TEM) were above 1 f/cm3; the authors note TEM results cannot be used for regulatory compliance.
  • All 10 chest X-rays were normal; CT scans were abnormal in 4 of 10 workers
  • Three workers had pleural calcifications on CT. Two of these three had circumscribed pleural thickening (plaques). All three had negative tuberculin skin tests.
  • The three workers with pleural calcifications were current or former riveters
  • Two workers had mild lung function abnormalities; the four workers with abnormal CT scans had normal lung function
  • No asbestos-related disease was diagnosed in any of the 10 workers
  • Only 1 of the 10 workers used respiratory protection
• The authors' conclusion: The authors concluded that the results provide preliminary evidence that workers in heavy vehicle brake repair shops could be at excessive risk of developing asbestos-related diseases
• Limitations the authors state:
  • Small sample size in number of shops and workers, which may limit generalizability
  • No formal control group for the respiratory health evaluation
  • Assigning zero to overloaded sampling windows underestimates average exposures
  • A negative tuberculin skin test does not completely rule out tuberculosis as a cause of the pleural findings

Topics

Medical terms in this study, explained in our Lexicon: Brake Lining, Asbestos Exposure, Personal Breathing Zone Sample, phase contrast microscopy (PCM), Time-Weighted Average (TWA), Pleural Thickening, Pleural Plaques.

Related studies

• Personal exposures to asbestos fibers during brake maintenance of passenger vehicles — M.F. Cely-García, M. Sánchez, et al. (2012)
• Estimation of personal exposure to asbestos of brake repair workers — M.F. Cely-García, F.C. Curriero, et al. (2017)
• Determining the frequency of asbestos use in automotive brakes from a fleet of on-road California vehicles — J. De Vita, S. Wall, et al. (2012)
• Mesothelioma and lung cancer among motor vehicle mechanics: a meta-analysis — M. Goodman, M.J. Teta, et al. (2004)
• Asbestos exposures of mechanics performing clutch service on motor vehicles — H.J. Cohen, D.R. Van Orden (2008)
• Mesothelioma among Motor Vehicle Mechanics: An Updated Review and Meta-analysis — D.H. Garabrant, D.D. Alexander, et al. (2016)

Browse more research in Journal of Exposure Science & Environmental Epidemiology, or return to medical research.