Epidemiological reports since 2000 have documented increased prevalence and
rapid progression of pneumoconiosis among underground coal miners in the United
States. To investigate a possible role of silica exposure in the increase, we
examined chest x-rays (CXRs) for specific abnormalities (r-type small
opacities) known to be associated with silicosis lung pathology.

Among miners from Kentucky, Virginia and West Virginia, the proportion of
radiographs showing r-type opacities increased during the 1990s (prevalence
ratio (PR) 2.5; 95% CI 1.7 to 3.7) and after 1999 (PR 4.1; 95% CI 3.0 to 5.6),
compared to the 1980s (adjusted for profusion category and miner age). The
prevalence of progressive massive fibrosis in 2000-2008 was also elevated
compared to the 1980s (PR 4.4; 95% CI 3.1 to 6.3) and 1990s (PR 3.8; 95% CI 2.1
to 6.8) in miners from Kentucky, Virginia and West Virginia.

The increasing prevalence of pneumoconiosis over the past decade and the change
in the epidemiology and disease profile documented in this and other recent
studies imply that US coal miners are being exposed to excessive amounts of
respirable crystalline silica.

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AplusA-online.de - Source: Occupational and Environmental Medicine