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 sufficiently long follow-up. Objectives Our objective was to examine this potential association in two large cohorts (ECRHS and SAPALDIA). Methods General population samples 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. FEV1 and FVC were jointly modelled 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 -15.1ml, -14.4ml and -18.7ml respectively, and FEV1/FVC -0.52%, -0.43% and -0.36% respectively, per 25 intensity-years of exposure). These declines were comparable in magnitude to those associated with long-term smoking. No effect modification by sex or smoking status was identified. Findings were similar between the ECRHS and 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.