Chronic obstructive pulmonary disease and longitudinal changes in pulmonary function due to occupational exposure to respirable quartz

Objectives The present study sought to examine the long-term effects of exposure to respirable quartz on pulmonary function with particular focus on chronic obstructive pulmonary disease (COPD). Methods The study is based on the Wismut cohort of former uranium miners. Spirometric data were ascertained together with quantitative estimates of cumulative exposure to respirable quartz for each of 1421 study subjects born between 1954 and 1956. The case definition for COPD is based on the criteria of the Global Initiative for Chronic Obstructive Lung Disease. Linear mixed regression models were fitted to identify significant determinants of longitudinal changes in lung function parameters. Results An average of five spirometries were available for each miner. It was shown that cumulative exposure to 1 mg/m(3)-year respirable quartz leads, on average, to a relative reduction in forced expiratory volume in 1 s/ orced vital capacity (FEV1/FVC) of 2.75% (p<0.001). A nested case-control approach demonstrated that the risk for COPD stage I increases with increasing cumulative exposure to respirable quartz (OR 1.81 per 1 mg/m(3)-year). Conclusions This paper adds further evidence on the long-term effects of exposure to respirable quartz, which include a decline in pulmonary function parameters and an increase in the incidence of COPD.