Cumulative occupational exposures and lung-function decline in two large general-population cohorts

Rationale: Few longitudinal studies have assessed the relationship between occupational exposures and lung-function decline in the general population with a sufficiently long follow-up. Objectives: To examine the potential association in two large cohorts: The ECRHS (European Community Respiratory Health Survey) and the SAPALDIA (Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults). Methods: General-population samples of individuals aged 18 to 62 were randomly selected in 1991-1993 and followed up approximately 10 and 20 years later. Spirometry (without bronchodilation) was performed at each visit. Coded complete job histories during follow-up visits were linked to a job-exposure matrix, generating cumulative exposure estimates for 12 occupational exposures. Forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were jointly modeled in linear mixed-effects models, fitted in a Bayesian framework, taking into account age and smoking. Results: A total of 40,024 lung-function measurements from 17,833 study participants were analyzed. We found accelerated declines in FEV1 and the FEV1/FVC ratio for exposure to biological dust, mineral dust, and metals (FEV1 =-15.1 ml, -14.4 ml, and -18.7 ml, respectively; and FEV1/FVC ratio =-0.52%,-0.43%, and-0.36%, respectively; per 25 intensity-years of exposure). These declines were comparable in magnitude with those associated with long-term smoking. No effect modification by sex or smoking status was identified. Findings were similar between the ECRHS and the SAPALDIA cohorts. Conclusions: Our results greatly strengthen the evidence base implicating occupation, independent of smoking, as a risk factor for lung-function decline. This highlights the need to prevent or control these exposures in the workplace.