A new study indicates exposure to heavy diesel exhaust fumes in workplace mines increases the risk of dying from lung cancer.

Mike Attfield led the initiative, titled “The Diesel Exhaust in Miners Study: A Cohort Mortality Study With Emphasis on Lung Cancer,” [PDF] that he said aimed to improve upon previous thoughts and research.

“They were all suggesting there was an effect of inhaling diesel exhausts on the development of lung cancer, not all of them, but when you assess the evidence from that, that was a pretty solid suggestion that they had,” Attfield said.

His study, which began in 1992, worked to remove the flaws in earlier analyses by expanding sample size, using accurate diesel exhaust metric readers and avoiding variables such as smokers or asbestos from the group.

The researchers looked at 12,350 workers who either worked in underground mines with diesel exhaust or surface workers, with similar exhaust in their work areas.

“It was across the United States. We had one salt mine, we had three potash mines, we had three trona mines and one limestone mine,” said Patricia Schlieff, a statistician for the project.

The subjects worked at mines in Ohio, New Mexico, Missouri and Wyoming.

The study found that mortality rates of lung cancer, esophageal cancer, and pneumoconiosis were higher in the group studied, but cases of bladder cancer, heart disease, or chronic obstructive pulmonary disease mortality were on par with people who didn’t work in those conditions.

The study summarizes an indication of “a higher lung cancer mortality risk associated with diesel exhaust (DE) exposure among ever-underground workers (i.e., those with the greatest DE exposures). Some evidence of an effect on lung cancer from DE exposure was also seen in surface-only workers. The exposure–response relationships were robust to variations in the methodological approach used in exposure assessment and essentially unchanged after adjustment for potential workplace confounders.”

The conclusion states: “The study findings provide further evidence that exposure to diesel exhaust increases risk of mortality from lung cancer and have important public health implications.”

A second, similar report "The Diesel Exhaust in Miners Study," [PDF] was led by Debra Silverman.  It looked at 12,315 workers at 8 mines and discovered 198 lung cancer deaths.