Variability, determinants, and associations with oxidative stress biomarkers of pentachlorophenol among Chinese pregnant women: A longitudinal study

Pentachlorophenol (PCP) is ubiquitous and moderately persistent in the environment, and it is an identified human carcinogen. Previous animal experiments indicate that toxic mechanisms of PCP include oxidative stress. However, no epidemiological study has reported the association between PCP exposure and oxidative stress; such association in pregnant women, a vulnerable population, is of particular interest. This study aimed to characterize PCP concentrations in 2304 urine samples from 768 pregnant women, explore its determinants, and evaluate the associations between PCP exposure and three oxidative stress biomarkers across three trimesters. The median concentrations of PCP (100% detected) in the first, second, and third trimester were 0.61, 0.59, and 0.48 ng/mL, respectively, with a significant decrease trend. The intraclass correlation coefficient of specific gravity (SG)-adjusted PCP was 0.26, indicating high variability for PCP across the three trimesters. PCP concentrations were significantly higher in older, pre-pregnancy overweight, multiparous, high-income, and employed women during pregnancy. Urinary PCP was markedly lower in samples collected during spring compared to other seasons. Linear mixed effect models for repeated measures revealed that ln-transformed SG-adjusted PCP was significantly associated with increased 8-hydroxy-2'-deoxyguanosine (8-OHdG; percent change [%Δ] caused by each interquartile range increase of PCP: 46.2, 95% confidence interval [CI]: 40.2, 52.5) and 8-hydroxyguanosine (8-OHG;%Δ [95% CI]: 44.8 [40.1, 49.8]), but the positive association with 4-hydroxy2-nonenal-mercapturic acid (HNE-MA) was not significant. PCP was also positively associated with increased 8-OHdG and 8-OHG in each trimester using general linear models, and its associations with HNE-MA were only significant at T1 (%Δ [95% CI]: 19.1 [1.05, 40.3]) and T2 (%Δ [95% CI]: 12.6 [0.32, 26.3]). Our findings provide valuable information about PCP exposure characteristics during pregnancy and the potential effects of PCP exposure on oxidative stress in pregnant women.