An international team of researchers from the U.S., Canada and South Africa found higher levels of silica dust in the lung tissue of present-day coal miners working in central Appalachia compared to the lung tissue of previous generations of coal miners.
In a paper published in the Annals of the American Thoracic Society, scientists explain that though silica is safe in rock formations, breathing in silica dust is highly toxic and prolonged exposure to silica dust can lead to severe lung disease.
The study points out that from 1970 to 2005, the rate of black lung cases among coal miners had been declining, largely due to improved occupational health practices required by federal regulations. However, since 2005, black lung cases, in general, have seen a three-fold increase, while long-term coal miners have seen a 10-fold increase in black lung cases.
When comparing the lung tissue of the current generation of coal miners to lung tissue collected from previous generations, silica seemed to be the common denominator that explains the previously unexplained rise in black lung cases.
"Mineralogic analysis showed the percentage (26.1% vs. 17.8%, p