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

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 non-detectable measurements. We applied bivariate normal regression to address the doubly left-censored situation where both the lung fiber concentration of non-commercial (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. We found a statistically significant positive relationship between TAA and AC (β = 0.49, 95%CI 0.11–0.86) and a not statistically significant relationship between DOE and TAA (β = 0.02, 95%CI −0.03–0.06). 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.