Fetal attraction: bisphenol A buildup in the womb?

Sep 30, 2011

Doerge, DR, NC Twaddle, M Vanlandingham, RP Brown and JW Fisher.  2011. Distribution of bisphenol A into tissues of adult, neonatal and fetal Sprague–Dawley rats.  Toxicology and Applied Pharmacology http://dx.doi.org/10.1016/j.taap.2011.07.009.

Synopsis by Joe Braun

A new study in rats reports that bisphenol A levels are higher in the fetus than in the mother, especially during the early parts of pregnancy.

A rodent study found that bisphenol A (BPA) levels were higher in the fetus during earlier parts of pregnancy when compared to the mother and newborns. However, the BPA only congregated in specific tissues when the rats were intravenously (IV) dosed with BPA and not when they were exposed by mouth.

While BPA exposure is widespread and frequent, scientists continue to debate its toxicity and human health risks.

There have been questions about whether BPA exposure during pregnancy can reach the fetus and impact fetal development. The fetus and child might be more susceptible to BPA exposure because of rapidly developing organs and an immature ability to detoxify substances.

BPA is a chemical used in a wide variety of consumer products, including polycarbonate plastics, food can linings, and thermal receipts.  A recent study also found that BPA levels are higher in women exposed to cigarette smoke.  Some cigarette filters may be made of BPA.

Because BPA is found in many products, people can ingest, absorb, or inhale the widely used chemical. The Centers for Disease Control has measured BPA in more than 90 percent of the U.S. population. It has also been detected in the umbilical cord blood of new borns, children, and pregnant women.

In this new study, researchers used rats to determine whether BPA levels were higher in the developing fetuses than in newborns and mothers. They administered BPA – either through food or by injection – to pregnant rats at different times of the pregnancy. Then they measured the concentration of BPA in the surrounding amniotic fluid and the developing fetal brain, liver and blood.

The researchers found that levels of BPA were higher in the fetus compared to the mother, especially in the early part of pregnancy. They also found that concentrations of BPA were higher in the fetal brain compared to other organs.

The concentration of BPA in the fetus and various organs depended on the way the researchers administered the BPA. When the pregnant rats received the BPA intravenously the levels were higher in the fetus. However, when the rats ate the BPA, the levels were similar between the mothers and fetus. Diet is thought to be the primary source of BPA in humans. But emerging information about the use of BPA in receipt papers is suggesting that dermal exposure may also be important.

While these results suggest that the fetus may not be exposed to BPA, the coniditions used in this particular experiment may not be applicable to humans.  This study used a single dose of BPA and humans are exposed to BPA at multiple times throughout the day.  In addition, the investigators measured BPA in the fetus 8 to 24 hours after the single dose.  BPA is rapidly metabolized and the detection of BPA can depend on the when BPA was measured in the fetus. 

The relevance of these results to humans remains to be determined since there is debate about comparing the results of animal and human studies of BPA.  Several studies of pregnant women and their children are currently examining the relationship between early life BPA exposure and child health.  These studies will help inform regulators about the toxicity of BPA.  

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