Underground coal mines that are unionized have significantly fewer traumatic injuries and fatalities per miner than nonunion mines, a federally backed study by a Stanford Law School professor concludes…the United Mine Workers of America, which has seen its ranks gradually wane in the face of mine companies' efforts to shake unionization, seized on the study…They said it was proof of their mission...In the past two decades, there have been 18-33 percent fewer traumatic injuries per miner in union mines than nonunion mines and 27-68 percent fewer fatalities per miner, according to a draft of the study sponsored by the National Institute of Occupational Safety and Health. [also refers to Massey Energy Co.]