26 February 2010
Plastic chemical BPA found to induce epigenetic changes
by Kate Melville
Scientists from Yale have shown how exposure to the ubiquitous chemical bisphenol A (BPA) induces epigenetic changes in pregnant mice that trigger hormonal imbalances in the later life of female offspring. BPA is an estrogen-like chemical that is a common component of plastics used to contain food. It is also used in baby bottles, refillable water bottles and the linings of metal food cans.
The new study, published in the FASEB Journal, suggests that exposure to BPA during pregnancy leads to epigenetic changes that may cause permanent reproduction problems for female offspring. "Exposure to BPA may be harmful during pregnancy; this exposure may permanently affect the fetus," said Yale's Hugh S. Taylor, co-author of the study. "We need to better identify the effects of environmental contaminants on not just crude measures such as birth defects, but also their effect in causing more subtle developmental errors."
Taylor made the discovery by exposing fetal mice to BPA during pregnancy and examining gene expression and DNA in the uteruses of female fetuses. The results showed that BPA exposure permanently affected the uterus by decreasing regulation of gene expression.
These epigenetic changes caused the mice to over-respond to estrogen throughout adulthood, long after the BPA exposure. This suggests that early exposure to BPA genetically "programmed" the uterus to be hyper-responsive to estrogen. Extreme estrogen sensitivity can lead to fertility problems, advanced puberty, altered mammary development and reproductive function, as well as a variety of hormone-related cancers.
Commentary accompanying the study suggests that it may only be in the future that the flow-on effects of BPA exposure are fully understood. "The BPA baby bottle scare may be only the tip of the iceberg," warned Gerald Weissmann, Editor-in-Chief of the FASEB Journal. "Remember how diethylstilbestrol [DES] caused birth defects and cancers in young women whose mothers were given such hormones during pregnancy? We'd better watch out for BPA, which seems to carry similar epigenetic risks across the generations."
Source: Federation of American Societies for Experimental Biology