19 December 2008

A recent study by Eric Garshick and colleagues reported that workers in the trucking industry who have had regular exposure to vehicle emissions have an elevated risk of lung cancer. The authors studied lung cancer risk in 31,135 unionized workers who were employed as long-haul drivers, pickup and delivery drivers, dockworkers, mechanics, hostlers, clerks and men employed in a combination of the first three categories. They found that lung cancer risks were significantly elevated in workers in two job categories: dockworkers and combination workers.

Lung cancer risks were also slightly higher in long-haul drivers and pickup and delivery drivers; however, these results were not statistically significant. There were no increases for hostlers, mechanics or men working in other jobs. The mortality risks increased with increasing years of employment.

The workers in the study were exposed to mixtures of air pollutants, including emissions from diesel trucks, gasoline vehicles, propane-powered forklifts, local traffic, as well as ambient background pollutants and secondhand cigarette smoke. Although the authors single out diesel exhaust as a major contributor to the increased lung cancer risk, this suggestion should be interpreted cautiously. Lung cancer risks were not elevated in the mechanics, even though they were exposed to the highest particulate matter (PM) and elemental carbon (EC) levels. It should be also noted that the dockworkers—who had the second-highest cancer risk—had the lowest PM and EC exposures.

The paper is one of a series of articles that report the results of a large National Cancer Institute-funded study of combustion particle exposures and lung cancer in the trucking industry. (Over eight papers have already been published and these are cited in the references.) The original objective of the study was to “asses the association of exposure to diesel exhaust with lung cancer mortality” in order “to detect (or refute) suggested carcinogenic effects of diesel exhaust.”

Because the results of this trucking industry study will be used by regulators—the study was already highlighted by the California ARB—an independent evaluation of the exposure and health findings would help to assess whether the reported increase in lung cancer risk can be linked to any specific pollutant.

The study, titled Lung Cancer and Vehicle Exhaust in Trucking Industry Workers, was published in the October 2008 issue of Environmental Health Perspectives.

Download the study