Asbestos Fiber Concentrations in the Lungs of Brake Repair Workers: An Updated Analysis Using Several Regression Methods to Handle Nondetectable Measurements

J Occup Environ Med. 2018 Jul;60(7):661-671. doi: 10.1097/JOM.0000000000001320.


Objectives: The aim of the study was to reanalyze an updated database of lung asbestos fiber levels for 21 brake repair workers who died of mesothelioma using robust maximum likelihood-based regression methods to address nondetectable measurements.

Methods: We applied bivariate normal regression to address the doubly left-censored situation where both the lung fiber concentration of noncommercial (TAA) and commercial amphiboles (AC) were subject to detection limits. For the single left-censored situation, we applied censored normal regression to study the relationship between duration of employment (DOE) and TAA.

Results: We found a statistically significant positive relationship between TAA and AC (β = 0.49, 95% confidence interval [CI], 0.11 to 0.86) and a not statistically significant relationship between DOE and TAA (β = 0.02, 95% CI, -0.03 to 0.06).

Conclusions: Our results provide additional support for the conclusion that exposure to commercial amphibole asbestos, and not chrysotile, is related to the occurrence of mesothelioma among some brake workers.

MeSH terms

  • Adult
  • Aged
  • Asbestos, Amphibole / analysis*
  • Asbestos, Amphibole / toxicity
  • Automobiles*
  • Humans
  • Limit of Detection
  • Lung / chemistry*
  • Maintenance
  • Mesothelioma / etiology*
  • Middle Aged
  • Occupational Diseases / etiology*
  • Occupational Exposure / adverse effects
  • Occupational Exposure / analysis
  • Occupational Exposure / statistics & numerical data*
  • Peritoneal Neoplasms / etiology*
  • Pleural Neoplasms / etiology*
  • Regression Analysis


  • Asbestos, Amphibole
  • tremolite