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Bisphenol A, more commonly known as BPA, is a chemical that is most frequently found in plastic containers and household products. Over the past years, researchers have studied the potential side effects of BPA exposure. In some studies, researchers concluded that BPA could be responsible for hindering child neurological development and emotional regulation. These studies reported that children exposed to BPA frequently tend to be more aggressive. In other studies, however, researchers believe that current exposure levels are not high enough to significantly impact behavior. Due to multiple contradicting findings, the extent to which BPA harms humans is debatable. In a new study, researchers discovered that BPA exposure affect sex-based behaviors in mouse models.

A research team, headed by Frances Champagne and her colleagues from Columbia University in New York, gave pregnant mice different dosages of BPA. Some mice received low dosages that they considered to be safe for humans while others were exposed to high amounts of BPA. Some of the offspring were killed right after they were weaned so that researchers could dissect and analyze their brains. The other offspring were observed and tested for behavioral changes.

The researchers found in the brain samples that there were sex-based changes in terms of how estrogen receptor genes were expressed. They also found changes in the expression patterns of DNA methylation, which suggested that there were some sex-related changes. Based from the observational part of the experiment, the researchers found that female rats were more inclined to get into fights, which is a behavior more often seen in male rats. Female rats also started sniffing and chasing other rats more than male rats did. Male rats also became less anxious while female rats acted more anxious than usual. All rats exhibited more aggressive behavior.

Critics of the study stated that the researchers' lowest dosage should still be considered high. Professor Richard Sharpe from the University of Edinburgh's Medical Research Council's Center for Reproductive Health stated that the two micrograms per kilogram given a day is nearly 10 to 20 times higher than normal BPA exposure. Furthermore, he states that estrogen levels tend to be higher in pregnant humans than pregnant mice, possibly influencing the effects of BPA.

The study was published in the Proceedings of the National Academy of Sciences.