The researchers used BPA levels at 16 and 26 weeks into pregnancy and at birth. (CBC)

Pregnant women exposed to a common chemical found in plastics are more likely to have daughters with aggressive and hyperactive behaviours, a new study that tested two-year-olds suggests.

Last year, Canada banned bisphenol A in plastic baby bottles. BPA, which makes plastic hard and shatterproof, is also used to make resins that line metal food and beverage cans, and is found in water bottles as well as consumer products such as CDs.

'If we want to protect kids, [the study] would suggest we need to protect pregnant women as well.'— Prof. Bruce Lanphear

Bruce Lanphear, a Simon Fraser University professor of children's environmental health, and his colleagues measured BPA levels in urine samples taken from 249 women in Cincinnati at 16 and 26 weeks into pregnancy and at birth to gauge how much of the chemical their fetuses had been exposed to.

Then, two years later, they assessed the children's behaviour, and noticed a pattern when it came to the young girls.

"We found that there was an association or linkage between those exposures and more aggressive and acting out-type behaviours in their two-year-old daughters," Lanphear said.

No significant effect was found among the boys, the researchers reported in Tuesday's issue of the journal Environmental Health Perspectives.

The findings are the first linking BPA exposure in the womb to changes in a child's behaviour. Other research involving much larger groups of women is planned to see whether the results hold up.

"What this study shows — along with the other animal toxicity studies — is that if we want to protect kids, it would suggest we need to protect pregnant women as well," said Lanphear, who is also a senior scientist at the Child and Family Research Institute at B.C. Children's Hospital.

Current regulations in Canada ban BPA from products that infants are exposed to, such as baby bottles. Lanphear said that at a minimum, industries should start labelling their products.

Avoidance tips

"The first thing to do is you can use alternatives, like glass and stainless steel," suggested Tanis Frame, who has two daughters and coaches parents on health issues through her business. "Stay away from any of the plastics so you don't have to worry about what's leeching out."

If people do use plastics, Frame said, they shouldn't be used for hot food or drinks.

The findings mean the chemical industry can no longer say animal studies are not applicable to human health, said Rick Smith, executive director of Toronto-based Environmental Defence, who called for BPA to also be removed from infant formula containers.

The American Chemistry Council pointed to what it called "significant limitations" in the study's design and said the study had failed to establish cause-and-effect relationships.

"The results of this preliminary and severely limited study cannot be considered meaningful for human health unless the findings are replicated in a more robust study," the group representing the industry said in a statement Tuesday.

With files from The Canadian Press