Women exposed to the chemical Bisphenol A (BPA) during pregnancy give birth to girls who exhibit unusually aggressive and hyperactive behaviors by age two. That's the finding from a study by University of North Carolina-Chapel Hill that measured the BPA levels in the urine of 249 Ohio women at three stages—during pregnancy at 16 weeks and 26 weeks and following birth. When the children turned two, their behavior was evaluated using the Behavioral Assessment System for Children-2 (BASC-2).
BPA is found in many common plastic items, from bottles to canned food lining to water pipes. According to the Centers for Disease Control and Prevention, some 93% of U.S. residents have detectable levels of BPA in their urine.
This study—published October 6, 2009, in Environmental Health Perspectives, was the first to look at the link between prenatal BPA exposure and childhood behavior. Early exposure to BPA during pregnancy looks like it may negatively impact the baby's developing nervous system—and have a particularly behavior-altering impact on growing girls.
"Girls whose mothers had higher BPA exposure were more likely to act like boys than girls whose mothers had lower BPA levels, especially if the exposure was seen earlier in pregnancy," said lead study author Joe Braun, a doctoral student in epidemiology at the UNC Gillings School of Global Public Health. "Boys" behavior did not seem to be affected, although there was some evidence of increased internalizing scores among BPA-exposed boys."
The researchers do not know why boys seem so much less affected by exposure to the chemical.