Lead author, Debra Silverman, Sc.D. and fellow researchers had set out to determine what the cancer risk from diesel exhaust exposure. Their study involved data on 12,000 miners at eight mines, all of them non-metal facilities. The researchers chose non-metal mines since there are low levels of other substances linked to cancer such as asbestos, silica, and radon.
The researchers chose to gather data on only underground mines since their heavy equipment tends to be run on diesel. In these conditions, exhaust fume levels accumulate to higher levels compared to other work settings like shipyards or trucking depots. The authors added that miners who work in underground mines faced diesel exhaust exposure levels several times higher than the exposure experienced by the greater population.
Diesel fumes exposure outcomes were reported in two complementary papers. The first paper examined the risk of death from any cause, but with a focus on lung cancer. The second paper examined details on deaths from lung cancer found in the previous study. The researchers also gathered data on other lung cancer risk factors such as smoking and a history of respiratory illnesses.
The researchers combined data on historical exposure information with thousands of measurements of diesel exhaust levels in the air of each mine. They quantified the levels of diesel exhaust by determining the amount of breathable elemental carbon.
Silverman claims, "It was vitally important to undertake a large study of diesel exhaust and lung cancer based on a quantitative assessment of historical exposure, taking into account smoking and other potentially relevant factors in order to estimate lung cancer risk."
Cohort study leader, Michael Attfield, Ph.D., wrote that in the case of underground workers facing the highest duration of exhaust exposure, the risk of developing lung cancer was five times higher than for those workers with the lowest exposure.
In the absence of factors like smoking, the risk was even further exacerbated. According to the papers, it was found that a non-smoking miner with the highest levels of diesel fumes exposure had a seven times higher risk of developing lung cancer when compared to a non-smoker with the lowest exposure.