Using certain plastics and cosmetics may increase the risk of breast cancer, according to emerging scientific research cited by Cornell investigators. Drinking from hard-plastic water bottles and using such personal-care products and cosmetics as shampoo, lotion and lipstick that contain certain chemicals can increase exposure to environmental estrogens that may contribute to breast-cancer risk.

To explain to young women why these everyday products should be avoided (see below), Cornell's Program on Breast Cancer and Environmental Risk Factors (BCERF) has produced and posted three short (up to four minutes) online videos.

"There is new evidence that even at very low levels environmental estrogens commonly found in such everyday products as cosmetics and certain plastics, as well as from environmental contaminants that get into our soil and water, can have additive effects," says Suzanne Snedeker, BCERF associate director for translational research.

Estrogen is a hormone produced by women's ovaries, but certain chemicals from everyday products can mimic estrogen's effects and can work together with the body's own estrogen to increase breast-cancer risk. In addition, most breast tumors depend on estrogen to grow.

"We know that life-long exposure to estrogen increases the risk of breast cancer. We are exposed to mixtures of many estrogenic chemicals every day. And even though these environmental estrogens are present at low levels, emerging research does suggest exposures to these chemicals can add up, and over time they may increase a woman's risk of developing breast cancer," Snedeker cautions. "Yet, many of these environmental estrogens can be avoided."

For instance, heat or scratches can cause an estrogenic chemical called bisphenol A to leach out of hard plastic water bottles. Bisphenol A is found in polycarbonate plastics with recycle symbol No. 7. While bisphenol A is not found in single-use water bottles, Snedeker recommends using stainless steel water bottles as the best environmental alternative.

Chemicals are looked at individually when assessing health risks, not as mixtures of chemicals, Snedeker points out. Since estrogenic chemicals are prevalent in so many products, there is concern that there is widespread exposure from multiple sources, and collectively these estrogenic chemicals may increase the risk of breast cancer.

"The Centers for Disease Control has started to look at levels in people and for the first time is documenting widespread exposure to a number of environmental estrogens," says Snedeker. "We are targeting young women now because we now know that lifelong exposure to estrogen increases breast-cancer risk, so anything young women can do to reduce their estrogen exposure, reduces their risk."

Using live-action video and animation, the videos point out, for example, that 70 percent of breast cancers are not genetic and that breast cancer may take decades to develop, so women in their teens, 20s and 30s can make informed choices and adopt habits to significantly reduce their risk.

The videos, which were supported by the New York State Department of Health, are available at http://envirocancer.cornell.edu/research/endocrine/videos/, and their Web sites offer additional information, including the science behind the recommendations. They were produced at Cornell's College of Veterinary Medicine by Jodi Korich, director of the Partners in Animal Health program, and her development team. The BCERF program is part of the Sprecher Institute for Comparative Cancer Research. For more information, contact Snedeker at 607-254-2893, or e-mail breastcancer@cornell.edu.