Chemicals in the Environment Contribute to Increased Breast Cancer Risk in Women, Report Says
Exposure to radiation, environmental toxins and common chemicals found in household items, such as plastic food containers, pesticides and paints, contribute "more than previously understood" to a person's breast cancer risk, according to a report released Thursday by the San Francisco-based Breast Cancer Fund and Breast Cancer Action, the Oakland Tribune reports. For the report, researchers analyzed 21 studies published since February 2003.
The Tribune reports that about 50% of breast cancers in women can be attributed to factors such as genetic predisposition, whether or not a woman has children, the age at which she gave birth and whether those children were breast fed (Fischer, Oakland Tribune, 10/7). However, the report states that fewer than one in 10 cases of breast cancer occurs in women with a genetic predisposition to the disease, and as many as 50% of breast cancer cases cannot be explained by traditionally accepted risk factors, according to a Breast Cancer Fund release (Breast Cancer Fund release, 10/7).
Three of the studies showed that chlorinated chemicals used in drinking water and many manufacturing processes, such as paper production, were associated with higher cancer rates.
Another study found that the hormone Zeranol, which is used to fatten beef cattle, contributes to the proliferation of breast cancer cells -- even at levels lower what FDA considers safe.
A separate study identified a new class of chemicals -- called "hormone sensitizers" -- that can increase cells' responsiveness to hormones such as estrogen, which helps breast cancer cells proliferate. The hormone sensitizer ethylene glycol methyl ether -- which is used in paints, varnishes, dyes and fuel additives -- and those similar to it "essentially sensitiz[e] cells to estrogen," the Tribune reports (Oakland Tribune, 10/7).
In addition, the breast cancer groups' report notes that an increased exposure to ionizing radiation -- an established cause of breast cancer -- from X-rays, CT scans, nuclear fallout and other sources might have contributed to the rise in breast cancer cases between 1950 and 1991 (Breast Cancer Fund release, 10/7).
Nancy Evans, an author of the report and a health science consultant for BCF, said, "When you're exposed to a chemical that makes cells more responsible to estrogen -- both your own estrogen and the estrogen in an oral contraceptive -- that makes them proliferate more. When they proliferate more, they have more of a chance of not following the program. In other words, they kind of spin out of control. That puts you on the pathway to cancer." She added, "We can't say breast cancer is all women's fault. There's very little testing going on of the chemicals out there. And there's no testing prior to market of the effects that these chemicals will have when they get into the environment."
Dr. Robert Hiatt, a professor of epidemiology at the University of California-San Francisco and author of a long-term study examining the effects of the environment on breast cancer, said, "There's no smoking gun." However, Hiatt, who is working with Evans to research the issue, added, "It's not like we're in a hopeless situation where things are spiraling out of control. ... A lot of stuff in the environment is getting into our systems and it's measurable. How much of this has a biological effect and a harm is another question."
Chris VandenHeuvel -- a spokesperson for American Chemistry Council, which represents about 90% of the nation's chemical manufacturers -- said, "Government and independent research into the causes of breast cancer have generally pointed to diet and lifestyle, not the low levels of modern substances that are present in the environment. People are living longer and healthier lives in part due to the many essential and lifesaving products of modern chemistry" (Oakland Tribune, 10/7). The report is available online. Note: You will need Adobe Acrobat Reader to view the report.