Researchers have found that exposure to bisphenol A (BPA) causes genetic changes that can cause changes in key areas of the brain in children. However, a diet rich in soy could help reduce some of these effects.

Bisphenol A or BPA is a chemical used in plastics and epoxy resins. The chemical can be found in water bottles, cups, impact resistant materials, compact discs, etc. Epoxy resin is used to coat metal products such as food cans, bottles and cups.

According to research, about 93 percent Americans have detectable levels of BPA in their body.

BPA has effects on children's behavior, brain and changes in prostate glands of infants. There is also some evidence regarding BPA exposure and altered time of puberty in girls.

"We knew that BPA could cause anxiety in a variety of species, and wanted to begin to understand why and how that happens," said Dr. Heather Patisaul, an associate professor of biology at NC State and lead author of a paper.

The study was conducted on animal models. Rats were fed with soy and a soy-free diet; some were also exposed to low doses of BPA from gestation to puberty meaning that these rats were tracked before they were born to the time that they became adult.

Researchers found that mice exposed to BPA had similar levels of the chemical that is commonly found in humans.

Rats that were fed a soy-free diet plus exposure to BPA had higher levels of anxiety than mice that had soy in their diet. Researchers were also able to tie these changes to altered gene expression in these mice.

Rats that didn't get soy had certain changes in a region called amygdala in the brain that lead to higher anxiety levels.

Researchers found two genes - estrogen receptor beta and the melanocortin receptor 4 - were affected due to exposure to BPA. Both these genes are required for release of a hormone oxytocin that is linked to social behavior. Any disturbance in this pathway can lead to social problems.

"Soy contains phytoestrogens that can also affect the endocrine system, which regulates hormones. It is not clear whether these phytoestrogens are what mitigate the effect of BPA, or if it is something else entirely. That's a question we're hoping to address in future research," said Dr. Patisaul.

The study is published in the journal PLOS ONE.