Breast Cancer Risks and the Environment: So Much We Don’t Know

Taken from the March/April 2012 issue of The Women's Health Activist Newsletter.

In December, the Institute of Medicine (IOM) released a new report, Breast Cancer and the Environment: A Life Course Approach.1 Commissioned by the Susan G. Komen for the Cure organization, the report reviewed evidence on breast cancer and the environment, explained the difficulties of studying how environmental factors affect breast cancer risk, and recommended both future research needs and ways to reduce breast cancer risk.

The IOM is a well-respected non-profit, non-governmental organization that produces reports on a wide range of health care issues. Komen is more controversial and has been criticized for allowing products to be marketed with its pink ribbon symbol while there are questions about whether those products contribute to breast cancer. One example is Komen’s “Promise Me” perfume, which is being reformulated after criticism that it contained a known carcinogen. Komen has also been criticized for focusing on mammography and “the cure” and spending relatively few dollars on prevention or research into breast cancer’s causes.2

The IOM report took a broad approach to “the environment” and included well-understood risks like smoking, obesity, alcohol consumption, and menopause hormone therapy. It gave somewhat less coverage to exposures women can’t readily modify that might require high-level regulatory change, like increasing product safety testing and reducing pollution. The IOM elected not to take a comprehensive approach to environmental issues, but to “focus on a limited selection of various types of environmental factors and potential routes of exposure.” The report addresses a number of consumer products components, but is not able to say much that is conclusive. For example, it describes perfume ingredient toluene as being “of concern” as a potential endocrine disrupter. So, although specific consumer products of concern are not addressed, the report may be a good reference for advocates who wish to raise concerns about potentially dangerous products and ingredients.

The IOM also explored the relatively well-documented risks of exposure to “ionizing” radiation, which occurs during medical imaging studies like X-rays, mammograms, and CT scans. It advises women to: “Avoid inappropriate medical radiation exposure” but qualifies the statement by adding that it “is not the committee’s intent to dissuade women from routine mammography screening, which aids in detecting early-stage tumors.” Routine mammography (especially in low-risk, younger women) has been controversial since the recent U.S. Preventive Services Task Force recommendation to replace routine screening of women in their 40s with individualized decision-making supported by more honest discussion of the very limited usefulness of mammography in pre-menopausal women. Komen rejected these recommendations, and the IOM report does not address this controversy at all. CT scans deliver the highest radiation doses, so women may at least be able to question the number of these higher-risk scans they receive based on the IOM report.

The IOM notes that more study is needed on several areas. One is shift work involving working at night, which is thought to increase risk. Studies on this issue included very few women of color, which presents a major limitation in understanding this potential risk. A lack of sufficient research is also noted for exposure to nail products, which is of concern both for customers and the largely female salon workforce. The IOM concludes that: “widespread lower level exposure of consumers suggests that this is an area for further inquiry.” The IOM also found insufficient evidence about risks from phthalates (found in many plastics, cosmetics, and food products), and states that it’s possible that bisphenol A (BPA) could pose a risk, but there is insufficient evidence about this possible toxin. The IOM indirectly addresses environmental pollution with sections on metals, industrial chemicals, and pesticides but provides very little guidance for women who might work in or live near potentially dangerous industries or pollution sources.

The clear thread, beyond well-known risks like smoking and radiation, is the lack of sufficient evidence and the difficulty in studying environmental factors. Women can’t readily be assigned to live downwind from a pollution source, or to use a certain consumer product. And, we’re exposed to so many different ingredients and substances that it is difficult to determine which, if any, increase our risks or what exposure levels are harmful. We’re also only beginning to understand how exposures may affect women differently based on their genetic make-up.

The lack of good data is exacerbated by a lack of regulation to require study before products are brought to market. As the IOM notes, “Premarket testing of chemicals used in consumer products and in industry is rarely undertaken because the federal government has limited authority to require it under the Toxic Substances Control Act. [TSCA]. Carcinogenicity testing is also generally not required before new cosmetics and dietary supplements are marketed. Manufacturers are responsible for identifying ingredients and declaring that they are safe for the intended use.”

This means — while there are serious gaps in our understanding of how chemicals affect breast cancer risk — it’s unlikely that we will get many clear answers in the short-term. These studies are difficult to conduct, and there is no regulatory reason companies should perform them. Hence, the most important activity we can engage in is to press for regulations requiring more extensive study and testing before products go to market, and ongoing safety studies for things already on the market.

For more information, see the coalition of health, environmental and advocacy groups proposing reform of the TSCA at Safer Chemicals, Healthy Families:

Rachel R. Walden, MLIS is a medical librarian and blogger for Women’s Health News and Our Bodies Our Blog.

The continued availability of external resources is outside of the NWHN’s control. If the link you are looking for is broken, contact us at [email protected] to request more current citation information.


  1. Institute of Medicine, Breast cancer and the environment: A life course approach. Washington, DC: The National Academies Press, 2012
  2. Susan G. Komen for the Cure Research Grant Programs, Available online at: Accessed: 1/20/2012.