Over the last 40 years, a woman’s risk of developing breast cancer in the United States has nearly tripled. Up to half of these cases are unexplained by genetics or lifestyle factors, according to “State of the Evidence 2006,” a new report that examines connections between the environment and breast cancer. Published by the Breast Cancer Fund and Breast Cancer Action, the report points to two likely culprits in rising breast cancer rates: synthetic chemicals and radiation.

“Compelling scientific evidence points to some of the 100,000 synthetic chemicals in use today as contributing to the development of breast cancer, either by altering hormone function or gene expression,” the report’s authors say. It also identifies radiation exposure from X-rays, CT scans and other sources as “the longest-established environmental cause of breast cancer.”

The report analyzes close to 350 scientific studies on possible links between environmental contaminants and breast cancer. Among the findings:

• Women exposed to common pesticides and herbicides including 2, 4D and chlordane and certain chlorinated pesticides had a higher risk for breast cancer.
• Scientists were aware of breast cancer risks from hormone replacement therapy as early as the 1930s.
• Phthalates, industrial plasticizers common in personal care products and other consumer goods, trigger the proliferation of human breast cancer cells. Some phthalates also reduce the effectiveness of tamoxifen in killing breast cancer cells.

Women in the U.S. have a one in seven chance of developing breast cancer. The disease was expected to claim more than 40,000 lives in the U.S. and more than 410,000 women around the world in 2005. Genetics and lifestyle risk factors such as consuming a certain level of alcohol or postponing childbirth until later in life fail to account for up to 50 percent of breast cancer cases.

“Considerable resources are spent each year to encourage women to make changes in their personal lives that might reduce the risk of breast cancer,” says Jeanne Rizzo, RN, executive director of the Breast Cancer Fund. “But many factors that contribute to the disease lie far beyond a woman’s personal control and can only be addressed by a revolution in thinking on the parts of government and the private sector.”

The report recommends ten steps to cut breast cancer risk and help stop the epidemic. These strategies include:

• Creating environmental health tracking programs at the state and federal level to monitor exposure to contaminants.
• Protecting workers from exposure to hazardous chemicals
• Holding corporations accountable for hazardous exposures and offering incentives for safe, green practices.
• Using the Precautionary Principle to develop a comprehensive chemicals policy that would require chemical and radiological producers to test the impacts of their products on health, safety and the environment before introducing them.