Enlarge By Ben Margot, AP Angie Garling, right, of Berkeley, Calif., reads while attending a Proposition 65 developmental and reproductive toxicant identification committee hearing with her 7-week-old daughter Nina Garling-Rai in Oakland, in July. A state board voted that the proposition would not cover BPA. GUIDE TO RECYCLING CODES GUIDE TO RECYCLING CODES HOW TO AVOID BPA EXPOSURE HOW TO AVOID BPA EXPOSURE • Avoid plastics with a #7 recycling code. • Choose baby bottles and cups labeled BPA-free. • Reduce use of canned foods and beverages; cans may be lined with BPA. • Choose powdered infant formula instead of liquid, again because metal cans may be lined with BPA. Source: Environmental Working Group A new study adds to the growing concern that prenatal exposure to the chemical bisphenol A could harm children's development. In the study of 249 pregnant women, the first to examine the effects of BPA on children's behavior, researchers found that girls whose mothers had the highest levels of BPA during pregnancy were more aggressive and hyperactive at age 2 than other girls. Findings appear today in the journal Environmental Health Perspectives. BISPHENOL A: What you need to know about 'everywhere chemical' Girls were more likely to be aggressive if their mothers had high levels of BPA — an estrogen-like chemical used in many consumer products — early in pregnancy or at about 16 weeks, the study says. A typical pregnancy lasts 40 weeks. The girls had aggression scores that were similar to those of boys, as measured by a commonly used test, says co-author Joe Braun of the University of North Carolina-Chapel Hill. Boys appeared unaffected by BPA. Braun says he plans to follow children until age 5, because behaviors can change over time. Michelle Macias, a doctor and spokeswoman for the American Academy of Pediatrics, notes that the increases in aggression were subtle. "Nothing in this study suggests that these kids have higher rates of behavioral disorders," Macias says. Pediatrician Lawrence Diller, who specializes in treating hyperactivity, notes that many other factors could have caused the girls' aggressive behavior. Scientists need to perform a more comprehensive study before sounding "alarm bells" about BPA, he says. A Food and Drug Administration report on BPA's safety is expected to be finished next month. Based largely on animal experiments, the government's National Toxicology Program last year expressed "some concern" about BPA's effects on the brain, behavior and prostate gland in children before and after birth. Hugh Taylor, an obstetrician/gynecologist at Yale University School of Medicine, notes that the new findings closely match the animal studies. And Taylor says the study raises concerns about the effect of exposing a fetus to an artificial substance that mimics estrogen. Although estrogen is often considered a "female hormone," it actually helps to "masculinize" the male brain around the 11th and 12th weeks of pregnancy, says neuropsychiatrist Louann Brizendine, author of The Female Brain. "In the developing brain, timing is everything," Brizendine says. "I'm worried that tiny amounts of this stuff, given at just the wrong time, could partly masculinize the female brain." And while BPA may not cause noticeable problems in individuals, it could have a much greater effect if the entire population is affected, so that children generally become more aggressive and hyper, says David Bellinger, a professor of neurology at Children's Hospital Boston. The new study actually may underestimate the link between BPA and aggression, Macias says. Children in the study came from well-educated families, whose children tend to have much lower rates of aggression and hyperactivity. In a more diverse population, the link between BPA and aggression might appear even stronger. Co-author Bruce Lanphear, a pediatrician at BC Children's Hospital in Vancouver, says there's already enough evidence to show that pregnant women should reduce their exposure to BPA. "We could end up doing a lot of harm by not acting," he says. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more