Temporal patterns of occupational asbestos exposure and risk of pleural mesothelioma.

Asbestos is the primary cause of pleural mesothelioma (PM). The objective of this study was to elucidate the importance of different temporal patterns of occupational asbestos exposure on the risk of PM using case-control data in male subjects. Cases were selected from a French case-control study conducted in 1987-1993 and the French National Mesothelioma Surveillance Program in 1998-2006. Population controls were frequency matched to cases by year of birth. Occupational asbestos exposure was evaluated with a job-exposure matrix. The dose-response relationships were estimated using restricted cubic spline functions in logistic regression models. A total of 2,466 ever-asbestos-exposed males (1,041 cases and 1,425 controls) were used. After adjustment for intensity and total duration of occupational asbestos exposure, the risk of PM was lower for subjects first exposed after the age of 20 yrs and continued to increase until 30 yrs after cessation of exposure. The effect of total duration of exposure decreased when age at first exposure and time since last exposure increased. These results, based on a large population-based case-control study, underline the need to take into account the temporal pattern of exposure on risk assessment.