Fetal bisphenol A exposure: Concentration of conjugated and unconjugated bisphenol A in amniotic fluid in the second and third trimesters

Bisphenol A (BPA) is an estrogenic compound widely used in polycarbonate plastics. The placental enzyme β-glucuronidase may deconjugate BPA into its “free” active form. We sought to quantify levels of conjugated and free BPA in second and third trimester amniotic fluid. Liquid chromatography coupled with mass spectrometry was used to measure BPA concentrations in 20 second trimester and 20 third trimester amniotic fluid specimens. Total BPA was detected in 16/20 second trimester samples; levels ranged from non-detectable to 0.75 ng/mL (median 0.47 ng/mL). Free BPA was detected in 9/20 second trimester samples; levels ranged from 0.31 to 0.43 ng/mL (median 0.38 ng/mL). Total BPA was detected in 2/20 third trimester samples. Free BPA was detected in 1/20 (0.42 ng/mL). When detected, free BPA comprised 83% and 91% of total BPA in second and third trimester amniotic fluid, respectively. Placental β-glucuronidase may deconjugate BPA, increasing fetal exposure to free BPA.

► BPA concentration in 2nd and 3rd trimester amniotic fluid was measured using LC–MS.
► Conjugated and free BPA are present in 2nd and 3rd trimester amniotic fluid.
► Free BPA is active, estrogenic form, comprises majority of BPA in amniotic fluid.
► Placental enzyme may deconjugate BPA; fetal liver has limited capacity to conjugate.
► Both may increase fetal exposure to the active, endocrine-disrupting form of BPA.