Low doses of the environmental contaminant bisphenol–A (BPA), widely used to make many plastics found in food storage containers, including feeding bottles for infants, can impair brain function, leading to learning disabilities and age–related neurodegenerative diseases, according to Yale researchers and colleagues.
"These data heighten concerns about the potential long–term consequences of human BPA exposure," said Neil J. MacLusky of Helen Hayes Hospital, who conducted the study with Csaba Leranth, M.D., professor in the Department of Obstetrics, Gynecology & Reproductive Sciences and in the Department of Neurobiology at Yale School of Medicine.
Leranth's group, which also included Tibor Hajszan, M.D., a research scientist at Yale, found that low doses of BPA in female rats inhibit estrogen–induction of synaptic connections in the hippocampus, an area of the brain involved with expression of sexually differentiated behaviors, as well as with formation and retention of memory.
Although estrogen is best known as one of the principal hormone products of the ovary, a number of studies over the last twenty years have shown that estrogen is also synthesized in the brain, where it contributes to the development and function of the hippocampus.
MacLusky said that high concentrations of BPA have been reported in the blood of some pregnant women and that BPA contamination could adversely affect human hippocampal development, with long–term effects on children's learning ability. Also, when the ability to make estrogen is impaired, as in old age, exposure to BPA could adversely affect hippocampal function and contribute to age–related neurodegenerative diseases such as Alzheimer's disease, in which hippocampal function is impaired.
About two billion pounds of BPA are produced annually in the United States. In addition to its use in plastics, BPA is found in dental sealants and prostheses. BPA derivatives are used as flame–retardants in adhesives, paper and textiles.