(CBS/AP) Exposure to diesel exhaust increases risk for lung cancer, new evidence shows, and workers are especially at risk.
Diesel exhaust has long been thought to be a carcinogen. But the 20-year study from the National Cancer Institute took a closer look by tracking more than 12,000 workers in certain kinds of mines - facilities that mined for potash, lime and other nonmetals. They breathed levels of exhaust from diesel-powered equipment higher than the general population encounters.
The study - published Mar. 2 in the Journal of the National Cancer Institute - found the most heavily exposed miners had three times the risk of death from lung cancer compared to workers with the lowest exposures.
But even workers with lower exposures had a 50 percent increased risk, study author Debra Silverman, an NCI epidemiologist, wrote.
"Our findings are important not only for miners but also for the 1.4 million American workers and the 3 million European workers exposed to diesel exhaust, and for urban populations worldwide," Silverman wrote.
Silverman noted that some highly polluted cities in China, Mexico and Portugal have in past years reported diesel exposure levels that over long periods could be comparable to those experienced by miners with lower exposures.
One industry group said that the study looked back at mines using decades-old equipment, and there's far less pollution from diesel engines today.
"Diesel engine and equipment makers, fuel refiners and emissions control technology manufacturers have invested billions of dollars in research to develop and deploy technologies and strategies that reduce engine emissions, now ultimately to near zero levels to meet increasingly stringent clean air standards here in the United States and around the world," Allen Schaeffer, of the nonprofit Diesel Technology Forum, said.
More people in the U.S. die from lung cancer than from any other type of cancer - it's expected to kill more than 160,000 Americans this year. The most recent statistics, from 1998 to 2007, show a decline in lung cancer rates among men and level rates among women.
The National Cancer Institute has more on lung cancer.