BPA and BPA metabolites in umbilical cord serum during mid-gestation in a northern California cohort

Abstract

Background: Bisphenol A (BPA) is a chemical widely used in numerous consumer products, resulting in nearly universal exposure among the U.S. population. BPA is an endocrine modulator and prenatal exposure is associated with numerous reproductive and developmental effects in animals. However, little is known about human fetal exposure or the ability of the fetus to metabolize BPA during mid-gestation. Objective: To measure fetal exposure to BPA and its metabolites during the 2nd trimester of pregnancy. Methods: We used targeted liquid chromatography-tandem mass spectrometry (LC/MS-MS) to measure unconjugated BPA and the two predominant BPA metabolic conjugates-BPA glucuronide and BPA sulfate- in fetal umbilical cord serum and maternal urine collected from voluntary 2nd trimester pregnancy terminations. Results: We detected unconjugated BPA (GM 0.16 ng/ml; range <LOD-52.26 ng/ml), BPA glucuronide (0.14 ng/mL; range <LOD-5.41 ng/mL) and BPA sulfate (GM 0.32 ng/mL; range <LOD-12.65 ng/mL) in all 85 cord serum samples examined. The conjugated to unconjugated ratio ranged from < 0.01 to greater than 300. Conjugated levels exceeded unconjugated levels in about three-quarters of the samples, but unconjugated levels were higher in samples with total BPA above the GM. In a subset of 29 matched maternal urine samples we found positive correlations between BPA conjugates in urine and cord blood (Spearman rho correlation 0.38 and 0.34 for BPA sulfate and BPA glucuronide respectively (p-value 0.07 and 0.04)). Total BPA levels were not correlated. Conclusion: We found universal fetal exposure to BPA with the novel finding of detectable BPA sulfate during mid-gestation among our study cohort. A small subset of fetuses had unconjugated BPA levels that exceeded what was measured in paired maternal urine samples.