Scientists Show Active BPA Crosses the Placenta

A new study shows that active BPA and its inactive metabolite freely cross the placenta from a pregnant mother to the fetus.

Balakrishnan and colleagues used human placentas gathered from Cesarean section births. A pump that simulated the mother's heart was hooked to the mother's blood vessels in the placenta. Solutions containing 10 nanograms per milliliter of BPA were pumped for several hours. This concentration was chosen because it is thought to be in the upper range of actual human exposures. The fluid that was pumped from the maternal side of the placenta to the fetal side was collected and levels of "free" and active form of BPA and the metabolized BPA-glucuronide were measured.

In the study, Balakrishnan and colleagues show BPA can cross the human placenta from mother to fetus. They found that 27 percent of the BPA applied to the mother's side of the placenta is carried to the fetal side.

In addition, more than 95 percent of the BPA recovered from the fetal portion of the placenta was still in the free, estrogenic, active form. Therefore, very little of the BPA that crossed from mother to fetus was inactivated, indicating that the human fetus is exposed to the estrogenic type of BPA.

The results are especially concerning because they indicate the fetus may be at greater risk from BPA exposures than previously thought. In non-pregnant adults, researcher believe BPA is rapidly converted to inactive forms like BPA-glucuronide and then removed from the body in urine. The findings suggest that adults can process BPA differently and are more protected from its effects than the fetus.

Exposure to BPA during fetal development is of paramount concern. BPA in its active form can act like an estrogen hormone, although its weaker than most natural hormones. In the womb, exposure to estrogens at the wrong time or in greater or lessen amounts than normal can cause adverse effects in the development of many organs and systems, including the male and female reproductive tracts, the brain, the mammary gland and the immune system.

For the past several years, scientific and regulatory experts have debated BPA's safety in light of its widespread exposure in adults, developing fetuses, infants and children. The U.S. Food and Drug Administration (FDA), the European Food Safety Authority (EFSA) and other regulatory agencies that determine whether exposure to chemicals like BPA is safe have come to different conclusions. Following the lead of the National Toxicology Program, the FDA’s latest decision is that BPA may cause adverse effects in humans, including altered brain development and behaviors.

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