Prenatal exposure to chemicals such as Bisphenol-A (BPA) and Diethylstilbestrol (DES) may increase the offspring's risk of breast cancer.  That is what Hugh S. Taylor, M.D., professor in the Department of Obstetrics, Gynecology & Reproductive Sciences at Yale School of Medicine found, at least. Taylor and his colleagues published their findings in the current issue of Hormones and Cancer.

Endocrine-disrupting chemicals, like BPA and DES, interrupt the proper functioning of hormones. This causes adverse immune, neurological, reproductive, and developmental effects in humans, and in other forms of wildlife. While BPA is a weak estrogen and DES is a strong estrogen, both can profoundly effect the breast's gene expression throughout life. 

Taylor was able to realize this after treating pregnant mice with BPA and DES. They then studied the adult offspring, and found that their mammary glands produced higher levels of EZH2. Humans with high levels of EZH2 are often diagnosed with an increased risk of breast cancer.

"These results show that all estrogens, even weak ones can alter the development of the breast and place our children at risk," comments Taylor. 

In summary, the research team found a mechanism by which the endocrine-disrupting chemicals regulate the breast's developmental programming. "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 says.

Taylor added the potential need to monitor women  who were exposed to chemicals such as BPA and DES in the womb for breast lesions. Safety concerns about exposures to environmental endocrine disruptors should be realized. BPA and DES may be found in plastics, such as water bottles. Many might recall the Nalgene water bottle scare, in which BPA was found to be the culprit

"We may not be able to see the final effects of these exposures until our children reach the age when breast cancers start to appear," adds Taylor. 

This study comes out at a time when research for breast cancer and the publicity around the disease is widely known and endorsed, as well as symbolized by images like the pink ribbon. While scientists continue to research to find a cure, the best way at combating the disease might in fact be prevention before the individual is even born.