We investigated the prevalence of Coal Workers' Pneumoconiosis (CWP) using the most recent five years of data from the U.S. Coal Workers' X-ray Surveillance Program. From October 1995 to October 2000, the program received 23,144 classifiable chest x-ray films for 20,590 miners at 1116 mines located in 15 states. Chest films were classified by a NIOSH A reader and one or more NIOSH B readers, using the International Labor Office 1980 Classification. Simple CWP was defined as films having reader agreement (based upon 42CFR37.52) for small opacity profusion I/0 or over. Progressive massive fibrosis (PMF) was defined as reader agreement on the presence of large opacities. The crude prevalence of simple CWP was 2.09% (431 cases), and of PMF, 0.17% (36 cases). Across the 15 states, simple CWP ranged from 0 to 5.32%; while PMF ranged from 0 to 0.42%. In surface, underground, and contract miners, CWP prevalence was 1.48, 2.27, and 7.14%, respectively. For ages <30, 30-39,40-49, 50-59, and 60+, prevalence of CWP was 0.05, 1.38,2.24, 2.71, and 3.93%; and of PMF, 0, 0.03, 0.18, 0.25, and 0.66%. 14,444 miners recorded a job history. For coal mining tenure of 0-10, 11-20, 21-30, and 30+ years, CWP prevalence was 0.71, 1.91, 2.77, and 3.47%; while PMF prevalence was 0, 0.09, 0.17, and 0.31%. Previous NIOSH reports have documented decreases in radiographic prevalence of CWP from 1970 to 1995. Our recent results highlight the importance of continuing attention to dust control for all miners and raise particular concern about exposures experienced by contract miners.
American Journal of Epidemiology, 2001 Congress of Epidemiology, Toronto, Canada, June 13-16, 2001