Abstract
PURPOSE: The Keokuk County Rural Health Study (KCRHS) is a longitudinal population-based study conducted in rural Iowa. A prior analysis of enrollment data identified an association of airflow obstruction with occupational exposures only among cigarette smokers. The current study used spirometry data from all three rounds to investigate whether level of forced expiratory volume in one second (FEV(1)) and longitudinal change in FEV(1) were associated with occupational vapor-gas, dust, and fumes (VGDF) exposures, and whether these associations were modified by smoking. METHODS: This study sample comprised 1071 adult KCRHS participants with longitudinal data. A job-exposure matrix (JEM) was applied to participants' lifetime work histories to assign exposures to occupational VGDF. Mixed regression models of pre-bronchodilator FEV(1) (millimeters, ml) were fit to test for associations with occupational exposures while adjusting for potential confounders. RESULTS: Mineral dust had the most consistent association with change in FEV(1), including ever/never ( - 6.3 ml/year) and nearly every level of duration, intensity, and cumulative exposure. Because 92% of participants with mineral dust also had organic dust exposure, the results for mineral dust may be due to a combination of the two. An association of FEV(1) level with fumes was observed for high intensity ( - 91.4 ml) among all participants, and limited to cigarette smokers with results of - 104.6 ml ever/never exposed, - 170.3 ml high duration, and - 172.4 ml high cumulative. CONCLUSION: The current findings suggest that mineral dust, possibly in combination with organic dust, and fumes exposure, especially among cigarette smokers, were risk factors for adverse FEV(1) results.