Occupational exposure to woodsmoke and oxidative stress in wildland firefighters.

Experimental studies indicate that exposure to woodsmoke could induce oxidative stress. However studies have not been conducted among the general population and specialized occupational groups despite the existence of elevated woodsmoke exposure situations. Therefore, we investigated whether there were across workshift changes in oxidative stress biomarkers among wildland firefighters who are occupationally exposed to elevated levels of woodsmoke. We collected pre- and post-workshift urine samples from 19 wildland firefighters before and after prescribed burns. We measured malondialdehyde (MDA) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) in the samples, and analyzed whether there were cross-shift changes in their levels, and the relationships between the changes and the length of firefighting career, age of firefighter, and quantified workshift exposure to particulate matter. Overall no significant cross-shift change was observed for 8-oxodG or MDA in the urine samples of the firefighters. Changes in both biomarkers were also not associated with PM2.5, which was used as a marker of exposure. However, overall unadjusted geometric mean 8-oxo-dG levels in the samples (31 μg/g creatinine) was relatively higher compared to those measured in healthy individuals in many occupational or general population studies. Additionally, cross-shift changes in 8-oxo-dG excretion were dependent on the length of firefighting career (p=0.01) or age of the subject (p=0.01). Significant increases in 8-oxo-dG level from pre-shift to post-shift were observed for those who had been firefighters for 2 years or less. The results indicate that oxidative stress response measured as cross-shift changes in 8-oxo-dG may depend on age or the length of a firefighter's career. These results suggest the need to investigate the longer term health effects of cumulative exposure of woodsmoke exposure among wildland firefighters, because increased body burden of oxidative stress is a risk factor for many diseases and is theorized to be involved in aging.