(Beyond Pesticides, May 15, 2007) According to a study commissioned by Susan G. Komen for the Cure and the Silent Spring Institute, 216 chemicals, many found in urban air and everyday consumer products, cause breast cancer in animal tests. The study, “Environmental Factors in Breast Cancer,” the most comprehensive review to date of scientific research on environmental factors that may increase breast cancer risk, was published in the online version of the American Cancer Society’s journal Cancer on May 14, 2007.
The state-of-the-science review collected and assessed existing scientific reports on potential links between specific environmental factors and breast cancer. The researchers synthesized national and international data sources and identified 216 chemicals that cause breast tumors in animals, including ten pesticides. They used the information to create a searchable online database featuring detailed information on the carcinogens. The database, accessible at www.komen.org/environment, is available free of charge.
The database includes references to 900 studies, 460 of which are human breast cancer studies that were critically evaluated by the research team. The studies measure breast cancer risk related to body size, physical activity, environmental pollutants, and prospective studies of diet. For each study, bibliographic information, key methods and findings, and a critical assessment of the strength of the evidence is included.
The database reveals that among the 216 compounds that cause breast tumors in animals:
- 73 have been present in consumer products or as contaminants in food;
- 35 are air pollutants;
- 25 have been associated with occupational exposures affecting more than 5,000 women a year;
- 29 are produced in the United States in large amounts, often exceeding 1 million pounds per year; and,
- 10 are pesticides: 1,2-dibromo-3-chloropropane, atrazine, captafol, chlordane, clonitralid, dichlorvos, fenvalerate, nifurthiazole, simazine, sulfallate.
Some of the chemicals on the list are fairly widespread, including mutagens associated with chlorine-disinfected drinking water and diesel exhaust. Yet for the most part, Ruthann Rudel, a senior scientist with Silent Spring Institute noted, regulators and environmental health doctors haven’t even looked for a connection between exposure and breast cancer risk in humans.
“You have to ask the question right, and if you don’t ask the question, you don’t see it,” Ms. Rudel added. “That’s been true for a long time in environmental health: You don’t always ask the right question when you start out.”
The study also examined lifestyle influences on breast cancer, such as physical activity and diet. The study results underscore the importance of regular, lifelong physical activity to lower a woman’s risk of developing breast cancer. The study concludes that further research is needed to determine the relationship between dietary factors and breast cancer risk.
“Komen is eager to see quality science yield answers that will eventually lead us to our ultimate goal of knowing how to prevent breast cancer,” said Hala Moddelmog, president and CEO of Komen for the Cure. “Commissioning this study is a step toward that goal, because it helps to determine what is known and what is not known about the possible link between certain environmental factors and the incidence of breast cancer.”
The study is one of several studies in recent years that has explored the link between pesticides and breast cancer.