Unborn babies may face “universal exposure” to bisphenol A (BPA)—a chemical used to make products like plastic water bottles, DVDs, medical devices, and food can liners.
Currently, the U.S. Food and Drug Administration (FDA) says that BPA is safe at the very low levels that occur in foods. However, in the past year the agency has banned the use of the chemical—which mimics the hormone estrogen—in baby bottles, children’s drinking cups, and infant formula packaging.
While consumer groups and legislators have fought to limit children's exposure to BPA in consumer products, some scientists have turned their attention to monitoring the levels of BPA babies experience in the womb, as well as studying the effects of the chemical on the development of animals before birth.
BPA Found in All Fetal Blood Samples
In a new study, Patricia A. Hunt, Ph.D., the scientist who investigated BPA's effects on maturing mouse eggs, and her colleagues found that the chemical was present in all umbilical cord blood samples taken from pregnant women having an elective procedure.
The 85 women in the study were tested during the second trimester of their pregnancy at a San Francisco clinic that serves Northern and Central California.
Researchers detected at least one type of BPA in all
the cord blood samples, either active BPA or forms converted by the
body, such as BPA sulfate.
The average levels of BPA detected were similar to those measured in cord blood samples taken from full-term infants in other studies. However, three of the samples had the highest BPA levels recorded in fetuses to date.
"Our findings suggest universal fetal exposure to BPA in our study population, with some at relatively high levels, and we provide the first evidence of detectable BPA sulfate in mid-gestation fetuses," the scientists from Washington State University and the University of California, San Francisco wrote in an article published online Aug. 13 in the journal Environmental Science & Technology.
Concerns About the Health Effects of BPA
“As a developmental biologist, I am extremely concerned about the levels these study authors have reported,” says Laura Vandenberg, Ph.D., a scientist at the University of Massachusetts, Amherst, who studies BPA but was not part of this study team. “But even more concerning is that the levels found in the fetal samples are very similar to levels that are known to cause harm in developing rodents.”
Several studies in animals have found possible health affects of BPA, including links to cancer, genital defects in males, early onset of puberty in females, obesity, and behavioral problems, such as attention deficit hyperactivity disorder.
In addition, a 2009 report from the National Toxicology Program expressed “some concern for effects on the brain, behavior, and prostate gland in fetuses, infants, and children at current human exposures to bisphenol A.”
Currently, the Environmental Protection Agency (EPA) uses only high doses to test the safety of chemicals.
However, in another study, published online last month in the journal Reproductive Toxicology, researchers found that mice exposed to lower doses of BPA in the womb had larger changes to their health, including increased weight gain, eating, and glucose intolerance.
The EPA defended its testing method in a response report.
Reason for High Levels of BPA Unclear
Not all scientists are convinced that BPA is dangerous to human health. Some have claimed that the BPA found in test samples is actually the result of contamination from supplies—which are made of plastic—used to collect and store the blood.
“It remains a strong point of debate in the BPA field whether there is free BPA circulating in the blood of people,” says Vandenberg. “This is important because, if BPA is rapidly cleared from the body, it has been argued that it should not have any biological effects.”
Researchers in the new study developed methods to prevent this type of contamination, but they still found BPA present in all of the cord blood samples.
The reason for high levels of BPA in the cord blood samples is unclear, though the researchers suggest that it could be a combination of high BPA exposure through the mother and the inability of the fetus’ immature metabolism to break down active BPA.
"Overall, our findings point to the importance of fetal exposure to BPA during development and the need to accurately assess the full range of human exposure during pregnancy," the authors wrote.