Study points the finger at rock dust as likely cause of increased black-lung disease in Appalachian coal miners

"New mining methods that churn up silica-laden rock are likely responsible for the surge of black-lung disease that has afflicted hundreds of miners across Central Appalachia in recent years, according to new research presented at the American Thoratic Society’s annual meeting this week," Will Wright reports for the Lexington Herald-Leader.

That's nothing new to people familiar with the reporting of Howard Berkes, now retired from NPR, but the study is the fclosest thing yet to scientific confirmation of the phenomenon. Robert Cohen, co-director of the Black Lung Center of Excellence, led the research.

Black-lung disease is caused by inhaling dust created by mining and transporting coal. The dust once came mainly from coal, but silica dust from cutting through the rock above and below coal seams is now the leading cause of the disease, because the thick seams have been mined. Mining thinner seams produces a larger ratio of rock dust to coal dust.

In 2014 the U.S. Mine Safety and Health Administration required mine operators to provide better dust sampling and allow less dust, but "dust" encompassed both coal and silica. Cohen said his research confirms that current regulations are inadequate and poorly enforced. "He also advocated that federal regulators should give silica its own regulatory designation, rather than rolling it into the existing coal-dust rule," Wright reports.

Cohen's project consisted of two studies. "The first examined tissue samples from 376 dead coal miners who participated in the National Coal Workers Autopsy Study. If found that the proportion of black lung primarily caused by silica increased from 24 percent before 1990 to 40 percent after 1990. Another 30 percent of cases were caused by a mix of coal dust and silica dust," Wright reports. 

The second study examined cause of death data for more than 34,000 miners and found that a higher percentage are dying from black lung than previous generations. "Black lung has contributed to the deaths of more than 76,000 miners since 1968, and while just 5 percent of miners had black lung in the late 1990s, that rate jumped to more than 20 percent in 2017, according to a National Institute for Occupational Safety and Health study published last year." Cohen's research also found that more younger miners are affected by the disease these days.