So now we know what happened; Mom ate too much canned tomato sauce and drank out of an old polycarbonate bottle. According to a new study, prenatal exposure to Bisphenol A (BPA) makes little girls as mean and aggressive as little boys.
Bisphenol A was originally proposed for hormone replacement therapy in the 1930s because it was so close to estrogen; most of the harmful effects attributed to it affect boys more than girls, although there have been suggestions that it makes girls fat and causes early puberty.
Evidently the female hormone estrogen "masculinizes" the male brain around the 11th or 12th week of pregnancy, and Bisphenol A may be doing the same for girls. In USA Today, neurobiologist Louann Brizendine, author of The Female Brain, says:
"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."
The study, released in Environmental Health Perspectives , describes how the researchers analyzed urine samples from 249 women at various times during pregnancy, finding small amounts of BPA (median concentration of 1.8 nanograms per millilitre at 16 weeks). They then tested the children at two years old using a "Behavioral Assessment System for Children":
A 134-item parent-reported assessment of a child's adaptive and problem behaviors in community and home settings. The Preschool version is appropriate for children age 2 to 5 years and has excellent reliability and validity for assessing adaptive and maladaptive behaviors.
They concluded that children born from women with the highest BPA concentrations were scored two points higher on the test.
They then go through a series of qualifications and note that children going through the terrible twos might mellow out as they grow, and will be looking at it again when they are five. But that didn't stop one of the co-authors, Vancouver pediatrician Bruce Lanphear from suggesting that pregnant women should cut back on their exposure to Bisphenol A. "We could end up doing a lot of harm by not acting," he says.
More on Bisphenol A (BPA):
New Study: BPA May Make You Stupid and Depressed
Gender Bender Chemicals Also Make You Fat
Bisphenol A Is In Your Tomato Sauce
BPA Danger may be greater from Tin Cans than Water Bottles