Effects of personal exposure to the oxidative potential of PM 2.5 on oxidative stress biomarkers in pregnant women.

Oxidative stress is a prominent pathway for the health effects associated with fine particulate matter (PM) exposure. Oxidative potential (OP) of PM has been associated to several health endpoints, but its impact on biomarkers of oxidative stress remains insufficient. 300 pregnant women from the SEPAGES cohort (France) carried personal PM samplers for a week and OP was measured using ascorbic acid (AA) and dithiothreitol (DTT) assays, and normalized by 1) PM mass (OP) and 2) sampled air volume (OP). A pool of three urine spots collected on the 7th day of PM sampling was analyzed for biomarkers, namely 8-hydroxy-2-deoxyguanosine (8-OHdG), malondialdehyde (MDA) and 8-isoprostaglandin-F2α (8-isoPGF2α). Associations were investigated using adjusted multiple linear regressions. OP effects were additionally investigated by stratifying by median PM concentration (14 μg m). In the main models, no association was observed with 8-isoPGF2α, nor MDA. An interquartile range (IQR) increase in OP exposure was associated with increased 8-OHdG (percent change: 6.2 %; 95 % CI: 0.2 % to 12.6 %). In the stratified analysis, exposure to OP was associated to 8-OHdG for participants exposed to low levels of PM (percent change: 11.4 %; 95 % CI: 3.3 % to 20.1 %), but not for those exposed to high levels (percent change: -1.0 %; 95 % CI: -10.6 % to 9.6 %). Associations for OP also followed a similar pattern (p-values for OP-PM and OP-PM interaction terms were 0.12 and 0.11, respectively). Overall, our findings suggest that OP may be associated with increased DNA oxidative damage. This association was not observed with PM mass concentration exposure. The effects of OP in 8-OHdG tended to be stronger at lower (below median) vs. higher concentrations of PM. Further epidemiological, toxicological and aerosol research are needed to further investigate the OP effects on 8-OHdG and the potential modifying effect of PM mass concentration on this association.