RODALE NEWS, EMMAUS, PA—Breast cancer now affects one in eight women in the U.S. every year, a 20 percent increase from 40 years ago. And despite all the pink ribbons, pink NFL sneakers, even pink KFC buckets, scientists aren't getting very close to discovering all the potential causes of the disease, or why it's getting more common. There are a few clear leads, of course, such as genetic predisposition and obesity, but more and more mainstream medical organizations are starting to look at environmental chemicals and other factors that could be influencing the ever-increasing rates of breast cancer.
"We now have sufficient data to be seriously concerned about the increased risk for many diseases, including breast cancer, that result from exposures to common environmental factors, especially those that interfere with the endocrine system," says Janet Gray, PhD, professor and director of the Program in Science, Technology & Society at Vassar College, and the author of a new report from the Breast Cancer Fund that explores the complicated link between chemicals in the environment and breast cancer. "We need to take this data seriously."
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THE DETAILS: The Fund first published its State of the Evidence report in 2002, says Gray, and over the past decade it's seen a number of shifts in the amount of research being conducted on breast cancer and environmental exposures, particularly in the area of chemicals used in plastic, such as bisphenol A (BPA) and phthalates. "More broadly," Gray says, "more research is being done on the class of chemicals that BPA and phthalates are part of, endocrine-disrupting compounds." Studies have shown that early lifetime exposure to those endocrine disruptors, the report notes, is linked to higher rates of breast cancer later on because they mimic the way that estrogen functions in the body; breast cancer is associated with a woman's total exposure to estrogen.
The timing of exposures is critical, says Gray. There are certain periods of a girl's life during which exposure to problematic chemicals, whether it's BPA in plastics or the endocrine-disrupting pesticides used on our food, could cause serious damage. "Those periods of high risk are consistent with what we know about breast physiology," she says. Exposures to chemicals in the womb and immediately after birth are crucial, she says, because that's when breast tissue is just developing. Similarly, during adolescence and during pregnancy, girls and women are experiencing incredible growth of breast tissue, and their bodies are easily influenced by chemicals and pesticides that act like estrogen.
The influence doesn't stop at environmental chemicals and pesticides, either. "Radiation is the one unequivocally accepted environmental cause of breast cancer," Gray says. "We know from studies in adolescents who were treated with radiation for all sorts of diseases 40 to 50 years ago that they have an increased risk of breast cancer, especially when those exposures were during childhood and adolescence." The type of radiation she's referring to is dubbed low-dose radiation and comes from X-rays, CT scans, and even mammography equipment—the very screening equipment that is intended to detect breast cancer early. "There were two studies published last fall indicating that exposure to radiation from mammography over the long term is associated with an increased risk of breast cancer, especially among women with a genetic predisposition to the disease," she notes. "This is just a demonstration of the exploding use of CAT scans and other screening tools that are hypothesized to be leading to thousands of cases of cancer every year."