Exposure to particulate matter (PM) from wildfire smoke has been linked to immune dysregulation underlying multiple health conditions, but data on the long-term effects of these exposures during gestation are lacking. PM smoke from wildfires occurring in urban areas is of particular concern because it also carries flame retardants from household furniture and polyaromatic hydrocarbons (PAHs) from combusted materials. The present study investigated the long-term associations between wildfire PM and serum flame retardants, PAHs, and lipid mediators (i.e., oxylipins) involved in immune regulation in participants from the B-SAFE (Bio-Specimen Assessment of Fire Effects) study, which enrolled women pregnant during or shortly after the 2017 Tubbs Fire in California (n= 140). Serum samples were collected and assayed 7 to 13 months post-exposure, at which point 20 women were still pregnant and 120 women were postpartum. Adjusted linear regression models revealed a significant positive association between increasing PM (μg/m³) exposure and serum concentrations of Benzo[k]fluoranthene, a PAH (β = 1.5223, P = 0.021, [95%CI: 0.235, 2.810]). No associations were observed between PM exposure and flame retardants or other PAHs. Increased exposure to PM was associated with lower serum concentrations of lipoxygenase (LOX)-derived oxylipins, including 20-OH-LTB4 (β = -0.9846, P = 0.041, [95%CI: -1.928, -0.042]), LTE4 (β = -1.1088, P = 0.035, [95%CI: -2.140, -0.077]), and 5-HETE (β = -0.6258, P = 0.035, [95%CI: -1.206, -0.046]). The diol to epoxide ratio (8,9-DiHETE/8,9-EpETE, β = 2.1512, P = 0.022, [95%CI: 0.324, 3.979]), a marker of immune activation via soluble-epoxide hydrolase (sEH), was increased with increasing PM exposure in pregnant but not lactating women. These findings provide new evidence of long-term effects of gestational PM exposure on lipid-mediators involved in immune activation (sEH pathway) and vasoconstriction (LOX pathway). Studies are needed to better understand the impact of these changes on maternal and child health.

Zhichao Zhang

PhD candidature, Univeristy of California Davis

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