The authors say the study is the first to show that BPA exposure permanently affects sensitivity to estrogen.
Researchers used two groups of mice, one exposed to BPA as a fetus during pregnancy and another exposed to a placebo. They examined gene expression and the amount of DNA modification in the uterus. They found that the mice exposed to BPA as a fetus had an exaggerated response to estrogens as adults, long after the exposure to BPA. The genes were permanently programmed to respond excessively to estrogen.
"The DNA in the uterus was modified by loss of methyl groups so that it responded abnormally in adulthood," said Hugh S. Taylor, M.D., professor in the Department of Obstetrics, Gynecology&Reproductive Sciences at Yale. "The gene expression was permanently epigenetically altered and the uterus became hyper-responsive to estrogens."
Taylor said that exposure to BPA as a fetus is carried throughout adulthood. "What our mothers were exposed to in pregnancy may influence the rest of our lives. We need to better identify the effect of environmental contaminants on not just crude measures such as birth defects, but also their effect in causing more subtle developmental errors."
Citation: Jason G. Bromer et al., 'Bisphenol-A exposure in utero leads to epigenetic alterations in the developmental programming of uterine estrogen response', FASEB J., Feb 2010; doi:10.1096/fj.09-140533