Effect of dust exposure and nitrogen oxides on lung function parameters of German coalminers: a longitudinal study applying GEE regression1974-1998

Purpose: Workplace limits for dust and nitrogen oxides are under review in Germany and the EU. We conducted a study on German coal miners to determine the effects of exposure on lung function. Methods: Longitudinal inception cohort study (1974-1998) on miners who began working underground at two coal mines between 1974 and 1979. We determined the number of shifts worked underground, the exposure to coal mine dust, quartz dust, nitrogen oxides (NO, NO sub(2)), smoking behavior, and three lung function parameters (FVC, FEV sub(1), FEV sub(1)/FVC). General estimation equation (GEE) models were fitted. Results: 1,369 miners worked an average 3,017 shifts (S) underground. The mean respirable coal mine dust concentration was 1.89mg/m[sup3 (quartz: 0.067mg/m[sup3), and the nitrogen oxide concentrations were 0.58ppm (NO) and 0.007ppm (NO sub(2)). On average, 9 measurements of lung function were available per miner. Compared to reference values, the findings were unexceptionable (103, 101, and 99%) on average. GEE-regression models did not reveal detrimental dust exposure effects. Nitrogen oxides (NO sub( x )=NO+NO sub(2) ) showed small but clearly insignificant effects on lung function: ' FVC=-0.0008ml/(220ppmS), P=0.86, FEV sub(1)=-0.003ml /(220ppmS), P=0.50 and FEV sub(1)%FVC=-0.07%/(220ppmS), P=0.22. Conclusions: The effect of dust exposure on lung function described in older British and American coal miner studies was not confirmed. This can be explained partly by differences in methods (here: longitudinal studies, no prior exposure), but also by lower dust levels. NO sub(x) exposures showed no relevant influence on lung function-a result confirming findings from British coal mining.