U.S. Watchdog Agency Backs Basis for Tightening Rules on Coal Dust Exposure

Deep work. Coal miners take dust measurements at the Cliffs Shafts Mine in Ishpeming, Michigan, in the 1940s.

Max S. Petersen/U.S. Bureau of Mines/Mine Safety and Health Administration

After an extensive review—including a visit to a working coal mine in Pennsylvania—a U.S. government watchdog agency has concluded that mine safety regulators relied on sound science in proposing a new rule designed to reduce miners' exposure to coal dust. Industry groups had challenged the research underlying the 2010 proposal, and late last year Congress asked its investigative arm, the Government Accountability Office (GAO), to look into the matter.

Since 1968, more than 75,000 U.S. coal miners have died from lung diseases caused by coal mine dust, today's GAO report notes. And recent studies have suggested that so-called black lung disease is on the rise, threatening more than 85,000 miners working in 26 states. In a bid to reduce the threat, in October 2010 the Department of Labor's Mine Safety and Health Administration (MSHA) proposed reducing allowable concentrations of coal mine dust, lowering the standard from 2.0 milligrams of dust per cubic meter of air (mg/m3) to 1.0 milligram per cubic meter. Coal industry groups, however, challenged the move, saying medical and dust sampling studies used to support the change were flawed. And some Republican members of the House of Representatives took up their concerns, adding language to an annual spending bill requiring GAO to review MSHA's data collection, sampling methods, and analyses.

Overall, MSHA-sponsored scientists "took reasonable steps" and "used appropriate analytical methods" to assure that their studies were sound, the report concludes. Medical researchers used "multiple x-ray specialists to reduce the risk of misclassifying disease," for example, and those studying mine conditions made "adjustments to coal mine dust samples where bias was suspected." The reviewers also found "no evidence of other findings or other methodological approaches that would call into question the underlying conclusions in the key scientific studies on which MSHA based its proposal."

Advocates for tighter mine safety rules in Congress welcomed GAO's findings, and said MHSA should move ahead with finalizing its proposals. "Rather than putting special interests above the public health, we should allow MSHA to publish a final version of the rule in the near future, so that more effective protections against black lung disease can be put into effect," Representative Rosa DeLauro (D-CT) said in a statement.