Occupational exposure to woodsmoke and associated changes in lung function and biomarkers of oxidative stress among wildland firefighters
Adetona, Olorunfemi Tosin
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Objectives: To: (1) characterize exposure of wildland firefighters to particulate matter with aerodynamic diameter less than 2.5 microns (PM2.5) and Carbon Monoxide (CO) in woodsmoke; (2) assess the utility of the relationship between exposures to PM2.5 and CO in woodsmoke as a tool for exposure control; (3) investigate the effects of occupational woodsmoke exposure on lung function among wildland firefighters and (4) investigate the effects of occupational woodsmoke exposure on oxidative stress by using urinary 8-hydroxy-2’-deoxyguanosine (8-OHdG) and malondialdehyde (MDA). Methods: Time integrated and real-time PM2.5 and CO were monitored in the breathing zones of wildland firefighters working at prescribed burns. Concurrent lung function measurements and urine samples for analysis of biomarkers of oxidative stress were also collected from the firefighters pre- and post-workshifts. Linear mixed effect models were used to estimate the correlation between workshift average exposures of the firefighters. Across shift changes in lung function and biomarkers of oxidative stress and the effect of cumulative exposure on lung function were also analyzed using linear mixed effect models. Results: Although geometric means of particulate matter exposure were below occupational exposure standards, they were at least 8 times the ambient air quality standard in the United States. Workshift averages of PM2.5 and CO were well correlated with each other (ρest=0.79, p<0.01). There were no across shift changes in lung function and biomarkers of oxidative stress. However, each additional day of exposure was estimated to be associated with declines of 24ml in pre-shift FVC and 24ml in pre-shift FEV1 (p<0.01). There was also evidence that across shift change in creatinine corrected 8-OHdG in the firefighters depended on the length of firefighting career or age of the subject (p<0.01). Conclusion: Wildland firefighters are exposed to elevated levels of PM2.5. Although acute health response as measured by across shift changes in lung function and biomarkers of oxidative stress was not observed, there is evidence that cumulative exposure to woodsmoke may cause some longer term health effects.