New evidence shows that heavy exposure to exhaust from diesel engines increases the risk of developing and dying from lung cancer, according to a study of non-metal miners in the United States. The research, part of the Diesel Exhaust in Miners Study, was carried out by scientists from the National Cancer Institute (NCI) and the National Institute for Occupational Safety and Health (NIOSH). The investigators tracked 12,315 miners at eight non-metal mining facilities including one limestone mine in Missouri, three potash mines in New Mexico, three trona mines in Wyoming and one salt mine in Ohio. The miners who work in the underground mines are believed to breathe varying levels of exhaust from diesel-powered equipment higher than the general population encounters. They only selected non-metal mines because there are low levels of other exposures that may be related to lung cancer risk, such as asbestos, silica and radon. Michael D. Attfield, Ph.D., who led the study at NIOSH, found that the most heavily exposed miners had a five-fold risk of death from lung cancer compared to workers in the lowest exposure category. But after taking into account smoking and other lung cancer risk factors, the risk of developing lung cancer was three times higher for the heavily exposed underground workers, said the study released Mar. 2 in the Journal of the National Cancer Institute. But even miners with lower exposures had a 50 percent increased risk, the author Debra Silverman, and NCI epidemiologist, wrote. The landmark study is important not only for the underground mine workers, but also for other workers exposed to diesel exhaust in the United States and abroad, and for people living in the urban areas, Silverman wrote.