Exposure early in life to an industrial chemical found in food containers and many other common products caused brain chemical changes in rats as well as behavioral changes in female animals, according to a new study. Results of the study will be presented Monday, June 4, at The Endocrine Society’s 89th Annual Meeting in Toronto.

Ayanna Alexander and Victoria Luine, PhD, of the City University of New York (CUNY) Graduate Center studied the effects of the chemical bisphenol A (BPA) in this study, funded by the National Institutes of Health. BPA is found in the linings of food cans and in plastic food containers, resin dental fillings and sealants, and baby bottles and toys. Microwaving and boiling can cause the chemical to leach into food materials, said Alexander, a doctoral student in biology and neuroscience at CUNY. In addition, BPA can contaminate drinking water, and it can cross the placental barrier in a fetus.

There has been concern about potential long-term harm from BPA exposure, according to Luine, a CUNY professor with an interest in neuroendocrinology. Laboratory and animal studies have shown that BPA interacts with estrogen receptors in the body. It either mimics the effect of estrogen or blocks the normal action of the sex hormone.

“We are especially concerned about exposure to BPA immediately after birth, because this is a critical time for brain development and sexual differentiation,” Luine said.

Alexander and Luine injected either saline (as a control) or a varying dose of BPA into 50 rats within the first week after birth. Both the low and high doses of BPA were higher than the maximum dose that the U.S. Environmental Protection Agency (EPA) recommends for humans, Luine said. Two months later when the rats were mature, they tested the animals in a maze for anxiety and spatial memory, the memory needed to navigate. They measured the animals’ weight and also measured levels of the brain chemicals dopamine, serotonin and norepinephrine. Researchers believe that these chemicals, called neurotransmitters, are altered in psychiatric and developmental disorders, such as depression, schizophrenia and attention deficit hyperactivity disorder.

Luine and Alexander found major differences in the effects of high-dose BPA depending on the sex of the rat. Compared with controls, females that received BPA had delayed onset of puberty, increased body weight and changes in behavior. Specifically, they had less anxiety and performed better on the spatial memory task than in controls, a task that males typically do better than females. Both male and female rats had increased brain chemistry activity in areas of the brain that correspond to anxiety and memory.

“We altered the normal pattern of development, perhaps permanently,” Luine said. “Other behaviors that we are unaware of also may have changed.”

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