Study confirms silica has driven uptick in black-lung disease

A new study has confirmed a widespread belief that the cause of black-lung disease in coal miners has shifted recently from coal dust to silica dust. Silica has likely driven a spike in more severe black-lung cases among younger miners in Central Appalachia, the study found, since no other major variables changed over the decades; regulations have remained mostly in place, in come cases getting more strict, and people haven't suddenly become more vulnerable to coal dust.

The University of Chicago-Illinois study, in the Annals of the American Thoracic Society, is the first to examine changes over time in the disease's pathology (how it looks under a microscope, in this case) and its mineralogy (which kind of dust caused it) by comparing miners' lung tissue samples going back more than 100 years. Dr. Robert Cohen, the lead researcher, told NPR that there has been indirect evidence of silica's role, "but his study was the first to examine lung-tissue samples for it.

Coal and silica cause different kinds of lung damage, and though most black-lung disease results from a combination of coal and silica inhalation, modern lung samples showed a greater percentage of silica damage and also a greater amount of silica damage overall.

Silica dust is released when miners drill through rock. It takes more rock drilling and excavation to get a ton of coal today, especially in Central Appalachia, because easy-to-reach coal, in thick seams, is gone.