Effects of fine particulate matter mass and chemical components on oxidative DNA damage in human early placenta

The effects of chemical components of ambient fine particulate matter (PM_2.5) on human early maternal-fetal interface are unknown. We estimated the associations of PM_2.5 and component exposures with placental villi 8-hydroxy-2'-deoxyguanosine (8-OHdG) in 142 normal early pregnancy (NEP) and 142 early pregnancy loss (EPL) from December 2017 to December 2022. We used datasets accessed from the Tracking Air Pollution in China platform to estimate maternal daily PM_2.5 and component exposures. Effect of average PM_2.5 and component exposures during the post-conception period (i.e., from ovulation to villi collection) on the concentration of villi 8-OHdG were analyzed using multivariable linear regression models. Distributed lag and cumulative effects of PM_2.5 and component exposures during the periovulatory period and within ten days before villi collection on villi 8-OHdG were analyzed using distributed lag non-linear models combined with multivariable linear regression models. Per interquartile range increase in average PM_2.5, black carbon (BC), and organic matter (OM) exposures during the post-conception period increased villi 8-OHdG in all subjects (β = 34.48% [95% CI: 9.33%, 65.42%], β = 35.73% [95% CI: 9.08%, 68.89%], and β = 54.71% [95% CI: 21.56%, 96.91%], respectively), and in EPL (β = 63.37% [95% CI: 16.00%, 130.10%], β = 47.43% [95% CI: 4.30%, 108.39%], and β = 72.32% [95% CI: 18.20%, 151.21%], respectively), but not in NEP. Specific weekly lag effects of PM_2.5, BC, and OM exposures during the periovulatory period increased villi 8-OHdG in all subjects. Ten-day cumulative and lag effects of PM_2.5, BC, and OM increased villi 8-OHdG in all subjects and EPL, but not in NEP; and the effects of OM were robust after adjusting for BC, ammonium, nitrate, or sulfate in two-pollutant models. In conclusion, placental oxidative DNA damage in early pregnancy was associated with maternal exposure to PM_2.5, especially its chemical components BC and OM.