Urinary biomarkers of PAHs, VOCs, OPEs, and metal(loid)s in firefighters responding in the wildland urban interface (WUI).

Firefighters suppressing wildland urban interface (WUI) fires may be exposed to smoke from burning vegetation as well as structures and vehicles. To better understand firefighters' internal dose exposures in the WUI environment, 250 firefighters from Southern California were enrolled into the Fire Fighter Cancer Cohort Study (FFCCS) in 2019, providing urine samples at enrollment and post-fire. One-hundred and twenty-five post-fire samples were collected from 89 participants. Samples were analyzed for metal(loid)s and metabolites of polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and organophosphate esters (OPEs). We assessed the difference between creatinine-corrected urine concentrations for each chemical at enrollment compared with post-fire, controlling for the individual participant. We also compared these concentrations to the general U.S. population concentrations from the National Health and Nutrition Examination Survey (NHANES) and the American Conference of Governmental Industrial Hygienists Biological Exposure Indices (BEIs) when available. All seven PAH and 11 VOC metabolite concentrations increased significantly from enrollment to post-fire. Diphenyl phosphate, antimony, and cadmium also significantly increased from enrollment to post-fire. Maximum post-fire concentrations in firefighters also exceeded the BEI for 1-hydroxyprene and trans,trans-muconic acid (a metabolite of benzene). Firefighters assigned to structure defense had significantly higher increases in PAH metabolites compared to those assigned to wildland firefighting tasks. Personal protective equipment (PPE) usage was not evaluated in this study, but future studies could combine personal sampling with the collection of detailed PPE usage to develop effective practices and decontamination strategies during WUI fire responses.