Prevalence of coal workers' pneumoconiosis among surface coal miners: Limitations and potential underreporting

Inhalation of coal mine dust causes coal workers' pneumoconiosis (CWP), a chronic, occupational lung disease and progressive massive fibrosis (PMF), a severe form of CWP. No studies of CWP prevalence among surface miners have been conducted since 2002, though they comprise 48% of the coal mining workforce. We assessed the prevalence, severity and geographic distribution of CWP in surface coal miners. Surface coal miners' (n=2,257; 7% of U.S. surface coal miners) chest radiographs taken by the National Institute for Occupational Safety and Health Coal Workers' Health Surveillance Program and were classified according to International Labour Organization pneumoconiosis standards. We identified 46 (2.0%) miners with CWP and 12 (0.5%) with PMF. The prevalence of CWP and PMF was greater (CWP: 3.7% vs. 1.1%; PR=2.7; 95% confidence interval [CI]: 1.4-5.3 and PMF: 1.2% vs. 0.1%; PR=12.4, 95% CI: 1.5-100.1) in central Appalachian (Kentucky, Virginia and West Virginia) miners when using log-binomal regression adjusting for underground and surface mining tenure. Surface miners are not included in the federally mandated periodic radiographic surveillance program established for underground coal miners, therefore participation in the NIOSH survey was voluntary, dependent on the cooperation of surface mine operators, and could have been influenced by a number of social factors (eg. known disease status, employer attitudes, safety culture, perceived risks). Consequently, these results may not reflect the true prevalence of CWP among surface miners. NIOSH recommends changes to the manner in which respirable dust is measured and suggests surface coal miners be included in periodic radiographic surveillance.