Research Debates BPA’s Influence in the Womb

BPA

Research on bisphenol A (BPA) — a building block of polymers — has lately focused on the prenatal exposure of the chemical.

For example, researchers at the University of Missouri found an association between BPA exposure in utero and later reproductive-associated behaviors in mice. In fact, the exposure affected males differently than females, reports Science Daily.

The website explains further how the differences were expressed:

In females, BPA reduced exploratory behavior that is essential for them to forage to provide nutritional support to her offspring. In contrast, California mice males exposed to BPA demonstrated reduced territorial marking, which is essential for them to defend a home range and their mate.

These findings could help provide a framework to guide researchers in developing human risk assessment studies, says Cheryl Rosenfeld, associate professor of biomedical sciences at the university’s Bond Life Sciences Center. “Risk assessment studies examining the impacts of BPA in humans could be more accurate if they took sex into account when monitoring for changes in children’s behavioral patterns,” she says.

BPA is used in a wide assortment of products, including paper receipts, plastic containers, and canned goods. Scientists are concerned that the chemical mimics the effect of female hormones and causes medical problems, such as cancer, learning disabilities, and immune system disorders.

Another concern is that exposure of the chemical leads to obesity in children. Washington State University researchers found a link between obesity in the descendants of rats exposed to BPA, reports Science 2.0. The study found “significant increases” in disease and abnormalities in the first and third generations of animals exposed to plastics.

Michael Skinner, a molecular biologist at the university, says:

Your great-grandmothers exposures during pregnancy may cause disease in you, while you had no exposure. This is a non-genetic form of inheritance not involving DNA sequence, but environmental impacts on DNA chemical modifications. This is the first set of studies to show the epigenetic transgenerational inheritance of disease such as obesity, which suggests ancestral exposures may be a component of the disease development.

But other research casts doubt on those findings. Researchers at the University of Michigan’s School of Public Health found that when female mice are exposed to BPA through their mother’s diet during gestation, the mice, when born, actually engage in hyperactivity and had leaner body mass than those not exposed to the chemical, reports Food Product Design. Why female offspring had such activity is not clear. However, BPA is thought to affect estrogen hormones, thus having more of a link to females.

“We looked at several different metabolic phenotypes, including spontaneous activity, food intake, energy expenditure and body composition,” says Olivia Anderson, doctoral student in environmental health sciences and lead author on the paper published in the Journal of the Federation of American Societies for Experimental Biology. “I think the most striking result we saw was the increased activity in these animals.”

Last December, these researchers also released a study that found that fetuses had difficulty ridding BPA from their systems. The study demonstrated that there is considerable exposure to the chemical during pregnancy and that fetuses are not as good at eliminating BPA from their bodies as adults.

In any case, scientists believe that more research needs to be conducted before firm conclusions can be drawn. They will pay more attention to early BPA exposure to look for more sex-specific responses.

Source: “Bisphenol A Affects Sex-Specific Reproductive Behaviors in a Monogamous Animal Species,” Science Daily, 1/11/13
Source: “Microbiologist Says BPA Seen Causing Disease Generations Later,” Science 2.0, 1/27/13
Source: “Mouse Study Contradicts BPS Link to Obesity,” Food Product Design, 1/29/13
Image by  The U.S. Food and Drug Administration.