Paraben mixture exposure and liver function in pregnant women: Findings from the Korean CHildren's ENvironmental health Study (Ko-CHENS)

Few studies have examined the association between parabens and liver function in pregnant women, who may be more vulnerable to endocrine-disrupting chemicals. This study aimed to examine the association between parabens and liver function markers in pregnant women. Data from 4791 pregnant women enrolled in the Korean CHildren's ENvironmental health Study (2015-2019) were analyzed. Urinary ethylparaben (ETP), methylparaben (MEP), and propylparaben (PRP) were measured before 20 weeks of gestation after creatinine adjustment and log-transformation. Liver function markers, log-transformed aspartate aminotransferase (AST), alanine aminotransferase (ALT), and albumin (ALB) were measured. Multivariable linear regression analysis (MLR), Weighted quantile sum regression (WQS), and Bayesian kernel machine regression (BKMR) were used to assess individual and mixed effects. ETP showed a significant and consistent negative correlation with serum ALB in all models (MLR: β = -0.0120, p < 0.0001; WQS: β = -0.0211, p = 0.0102; BKMR: PIP = 1.000). PRP was positively associated with ALT (MLR: β = 0.0071, p = 0.0200) and was the largest contributor in the mixture models (BKMR: PIP = 0.6090). MEP showed a significant positive correlation with AST and ALT levels in MLR, but its contribution was low in the mixed-exposure model. BKMR analysis showed linear and nonlinear relationships between paraben exposure and liver function markers, with AST and ALT increasing, and ALB decreasing across exposure levels. This is the first study to report a significant association between urinary paraben exposure and liver function markers in pregnant women. Higher urinary paraben concentrations measured during early pregnancy may potentially be associated with subtle alterations in liver function markers.