Arachidonic Acid Metabolites in Self-Collected Biospecimens following Campfire Exposure: Exploring Non-invasive Biomarkers of Wildfire Health Effects

Climate change has contributed to the increased frequency and intensity of wildfires. Studying its acute effects is limited due to the unpredictable nature of the occurrence of wildfires, which necessitates readily deployable techniques for collecting biospecimens. To identify biomarkers of the acute effects of wildfires, we conducted this exploratory study in eight healthy campers (four men and four women) who self-collected nasal fluid, urine, saliva, and skin wipes at different time points before, during, and after exposure to wood smoke for 4 h during a camping event. Concentrations of black carbon in the air and polycyclic aromatic hydrocarbons in participants' silicone wristbands were significantly increased during the exposure session. Among 30 arachidonic acid metabolites measured, lipoxygenase metabolites were more abundant in nasal fluid and saliva whereas cyclooxygenase and non-enzymatic metabolites were more abundant in urine. We observed drastic increases, 8 h following the exposure, in urinary levels of PGE2 (398%) and 15-keto-PGF2 alpha (191%) [false discovery rate (FDR) < 10%], with greater increases in men (FDR < 0.01%) than in women. No significant changes were observed for other metabolites in urine or the other biospecimens. Our results suggest urinary PGE2 and 15-keto-PGF2 alpha as promising biomarkers reflecting pathophysiologic (likely sex-dependent) changes induced by short-term exposure to wildfires.