Prenatal exposure to BPA behind breast cancer?

Exposure in the womb to chemicals can raise offspring`s risk of breast cancer.

Updated: May 29, 2010, 20:37 PM IST

Washington: Exposure in the womb to chemicals like Bisphenol-A (BPA) and Diethylstilbestrol (DES) can increase an offspring`s risk of breast cancer, according to a new study.

Researchers at Yale School of Medicine found that BPA and DES, called endocrine-disrupting chemicals, are substances in the environment that interfere with the proper functioning of hormones. This disruption results in adverse developmental, reproductive, neurological and immune effects in both humans and wildlife.

Although BPA is a weak oestrogen and DES a strong oestrogen, both affect gene expression in the breast throughout life, according to lead author of the study Hugh S. Taylor, MD, professor in the Department of Obstetrics, Gynaecology & Reproductive Sciences at Yale School of Medicine.

In an experiment on pregnant mice, the researchers found higher levels of EZH2 in the mammary glands after treating them with BPA and DES. EZH2 is a protein that controls the expression of all genes. Higher EZH2 levels are associated with an increased risk of breast cancer in humans.

"These results show that all estrogens, even weak ones can alter the development of the breast and place our children at risk," said Taylor, who is also a member of Yale Cancer Center. "We many not be able to see the final effects of these exposures until our children reach the age when breast cancers start to appear."

"The data, coupled with our data on DES and BPA effects on the uterus, clearly demonstrate a lasting effect of prenatal exposure to estrogens on the breast and uterus," Taylor added. "This study generates important safety concerns about exposures to environmental endocrine disruptors such as BPA and suggests a potential need to monitor women exposed to these chemicals for the development of breast lesions as adults."