Continued Increase in Prevalence of Coal Workers' Pneumoconiosis in the United States, 1970-2017.

OBJECTIVES: To update prevalence estimates for coal workers' pneumoconiosis (CWP) among working underground coal miners in the United States.

METHODS: We conducted a prevalence study using radiographs collected from 1970 to 2017. We classified each radiograph using international standards. We defined CWP as the presence of small opacities, with profusion greater than or equal to subcategory 1/0, or the presence of a large opacity larger than 1 centimeter.

RESULTS: Following a low point in the late 1990s, the national prevalence of CWP in miners with 25 years or more of tenure now exceeds 10%. In central Appalachia (Kentucky, Virginia, West Virginia), 20.6% of long-tenured miners have CWP. When we excluded miners from central Appalachia, the prevalence for the remainder of the United States was lower, but an increase since 2000 remains evident.

CONCLUSIONS: The national prevalence of CWP among working coal miners is increasing. This increase is most pronounced in central Appalachia. Current CWP prevalence estimates will likely be reflected in future trends for severe and disabling disease, including progressive massive fibrosis. Public Health Implications. Recently enacted protections to prevent coal mine dust exposure and identify CWP at its early stage remain essential to protect US coal miners.