Longitudinal and cross sectional analyses of exposure to coal mine dust and pulmonary function in new miners.
Seixas-NS; Robins-TG; Attfield-MD; Moulton-LH
Br J Ind Med 1993 Oct; 50(10):929-937
Longitudinal and cross sectional changes in pulmonary function in new coal miners were studied. The cohort consisted of 977 coal miners who first started work in 1970 and who were studied in round two, 1972 to 1975, and round four, 1985 to 1988, of the National Study of Coal Workers Pneumoconiosis. Data collected in both rounds included chest X-rays, a questionnaire survey of respiratory symptoms and smoking habits, work history, and measurements of forced vital capacity (FVC) and 1 second forced expiratory volume (FEV1). Cumulative coal dust exposures were estimated from personal monitoring data collected for legal compliance purposes in 36 mines between 1970 and 1988 by the Mine Safety and Health Administration. Associations between cumulative dust exposure and changes in FVC and FEV1 within each round and between rounds were examined by logistic regression techniques. At the start of round four of the survey, the average age of the cohort was 39.9 years and the average cumulative coal dust exposure was approximately 15mg/m3 years (yr). Approximately 35% of the subjects were current smokers. FEV1 and FVC decreased between round two and round four at an average rate of 39 and 37 milliliters (ml) per yr, respectively. Cross sectional analysis of round 4 data indicated that decreases in FEV1 and the FEV/FVC ratio were significantly associated with cumulative coal dust exposure. The effect on FEV1 was estimated to be -5.9ml/mg/m3 yr. Cross sectional analysis of the round two data indicated that both FVC and FEV1 were decreased by about 30ml per each mg/m3 yr cumulative dust exposure. The decreases in FVC and FEV1 occurred primarily in miners older than 25yr of age. Exposure related decreases in FVC and FEV1 were seen in smokers, nonsmokers, and former smokers. The largest decreases occurred in former smokers. The authors conclude that exposure to respirable coal dust at concentrations present in US mines since 1970 seems to have a major effect on FEV1 and FVC. The effects are nonlinear being most pronounced during the first years of exposure.
NIOSH-Publication; NIOSH-Author; NIOSH-Grant; Pulmonary-system-disorders; Coal-miners; Coal-dust; Occupational-exposure; Epidemiology; Pulmonary-function-tests; Cigarette-smoking; Occupational-medicine
Environmental & Indust Health University of Michigan Dept of Envir/indust Health AN Arbor, MI 48109-2029
British Journal of Industrial Medicine
University of Michigan at Ann Arbor, Ann Arbor, Michigan