In the minds of many, the plastic additive BPA is a four-letter word, as it’s been linked to a variety of problems, from reduced female fertility to increased diabetes risk. A new study on its effects on children’s cognitive development won’t help its case any: the research finds that in utero exposure, rather than childhood exposure, may be responsible for developmental problems in children by age three.

In the new study, the researchers measured women’s BPA levels when they were 16 and 26 weeks pregnant, and later, the children’s BPA levels at one, two, and three years of age. They had the mothers fill out surveys in order to determine the behavioral characteristics of the children.

For each 10-fold increase in the pregnant women’s BPA levels, the children had more anxiety, hyperactivity, and depression, and lower emotional control and inhibition.

The researchers found BPA in 97% of the pregnant women and their children. This prevalence may sound extraordinary, but in truth, because of the ubiquity of BPA in everything from water bottles to medical equipment to dental seals to store receipts, it’s found in the bodies of most people in the industrialized world.

The unexpected part of the findings followed. For each 10-fold increase in the pregnant women’s BPA levels, the children had more anxiety, hyperactivity, and depression, and lower emotional control and inhibition. "None of the children had clinically abnormal behavior, but some children had more behavior problems than others,” said lead researcher Joe Braun. And it wasn’t the children’s BPA levels that were linked to differences in behavior, it was just their mother’s.

Even more intriguing was that after controlling for outside variables, the effect was found in girls, but not boys. The authors suggest that because BPA is known to be a hormone disruptor, it’s possible that it interacts with the hormone or neurotransmitter pathways differently in males and females. They do caution that because of methodological considerations, more research is needed before jumping to any conclusions about BPA and gender.

Still, the authors do say that clinicians might want to advise their pregnant patients to reduce intake as much as possible, since there does seem to be some connection between prenatal BPA exposure and behavior in kids. More research will clearly be needed to understand the relationship more fully, but there’s certainly no harm in being careful about BPA consumption now. According to the authors, “BPA exposure can be reduced by avoiding canned and packaged foods, receipts, and polycarbonate bottles with the recycling symbol 7.” For more information on BPA safety, see the NIH’s website on this subject.

Joe Braun is a researcher at the Harvard School of Public Health; the study was published in the October 24, 2011 online issue of the journal Pediatrics.