Blog posted on the site of the National Resources Defense Council (NRDC),, Dec. 8, 2011. Reprinted with permission of the author.

Sarah Janssen

Yesterday, the Institute of Medicine (IOM) released a report on breast cancer and the environment. The report (downloadable for free) was commissioned by the Susan G. Komen foundation and was written by a committee of experts who spent over a year reviewing and summarizing scientific evidence. The committee adopted a broad definition of “environment” to include anything that didn’t involve factors inherited through DNA.

The 360-page report was widely covered in the media yesterday and many of the headlines focused on personal responsibility for avoiding the “environmental” factors identified as being most strongly linked to breast cancer. The advice will not be new to most of you – don’t smoke or hang out around smokers, don’t drink excessively, don’t take hormone replacement therapy, avoid unnecessary medical radiation, and maintain your ideal weight and get regular exercise.

However, with a few exceptions, most of the news articles did not delve deeper into the report nor discuss some of its more significant recommendations. Unfortunately, the impression that many of the headlines left was the ability to avoid breast cancer is in your control, if you just live a healthy life. However, the report was much richer than this and there were some important observations and recommendations which were left out of the mainstream media reports that I think are important to point out.

First for the Komen foundation, this report is a significant step forward in the [sic] turning the conversation from how to cure breast cancer to how to prevent it. While we have made great strides in better detection and treatment of cancer, there has not been much of an emphasis on how to prevent breast cancer in the first place or in identifying factors which might cause it. This report starts that conversation at a national level.

Second, the report did identify a number of chemicals which have been linked to breast cancer, many which are found in cigarette smoke, such as benzene and 1,3-butadiene. Other chemicals such as pesticides, BPA, phthalates and [sic] were reviewed and found to have “biological plausibility” for causing breast cancer, but because there had not been an authoritative review by a government body or because most of the research had been done in animals, the committee concluded further research was needed.

Somewhat paradoxically, while the committee stated there wasn’t enough human research, the committee also recognized that it is not possible to do large scale human experiments with chemicals found in our every day environment and that at a population level, their impacts could be significant. Based on limited human data with supporting animal data, the committee actually supported government regulation of these chemicals, by making these statements, “The committee recognizes, however, that existing data indicate that BPA and some other substances may be hazards to human health and may well warrant consideration of actions by regulatory agencies that are aimed at reducing future population-based exposures.” and “Other considerations for regulators may include the possibility that exposure to multiple chemicals that contribute to mechanisms involved in breast cancer (e.g., mutagens, endocrine disruptors, etc.) may present a cumulative risk that could be controlled in part through regulatory actions on individual substances.” (IOM report, p. 6-18)

Third, the committee acknowledges that limited chemical testing data exists in our current regulatory environment which does not require chemicals be tested before they enter the market. Most chemicals have never undergone any toxicity testing. And if they have undergone some testing, most have never been tested for their impacts on the development of breast cancer.

This is one of the biggest reasons we need reform of federal chemical policy laws, such as TSCA, and why this is an issue that NRDC has been working on for several years. The committee encouraged “… efforts to better inform consumers and health professionals about the limits of FDA’s role, to encourage manufacturers to identify hormonally active ingredients in cosmetics and dietary supplements, and to ensure that FDA has effective tools to identify contaminants or ingredients that are potential contributors to increased risk of breast cancer.” and also “…encourage manufacturers to improve testing and make existing information on their products more readily available.” (IOM report, p. S-10)

Fourth, the report makes 13 research recommendations for better identifying and characterizing environmental links to breast cancer. Many of the recommendations are thoughtful and if incorporated, could make significant inroads into our understanding of breast cancer causation.

One overarching recommendation is that future breast cancer research considers the entire life course. As our scientific knowledge has grown, we have learned that breast development begins in the womb and continues through pregnancy and lactation. However, much of the breast cancer research looking at chemical exposures has focused on adult animals. By looking at exposures during critical periods of development, we will gain more useful information about how breast cancer develops and how important exposures during these vulnerable periods are.

Many of these recommendations support the recommendations made recently by another expert committee, the Breast Cancer and Chemicals Policy project supported by the California Breast Cancer Research Program. I was co-director of that project and have blogged previously about the report.

These recommendations include calls for research that incorporate the entire life course from prenatal through adult life, that identifies early changes that herald the development of breast cancer and could predict a chemical to be a carcinogen, that focuses on mechanisms such as endocrine activity and epigenetic changes, and that considers the impact of mixtures of chemicals. It makes important recommendations for improved chemical testing that could be started today if only the resources were directed towards them.

I hope that regulatory agencies and the Komen foundation will look beyond the headlines of this report and take these research recommendations seriously by directing more of the research dollars towards them.

Sarah Janssen, MD, PhD, MPH – Dr. Sarah Janssen is a senior scientist in the Health and Environment Program of the Natural Resources Defense Council (NRDC). In her capacity as a scientist with NRDC, Dr. Janssen provides scientific expertise for policy and regulatory decisions on a number of toxic chemicals, including hormone-disrupting substances which interfere with fertility and reproduction. Her work has included research on flame retardants, cosmetics, plastics and plasticizers, breast cancer and threats to adult reproductive health and child development. Dr. Janssen is the author of numerous peer-reviewed publications and book chapters.