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Janet Gray, Ph.D.
Janet Gray, Ph.D.

As author of our 2008 and 2010 State of the Evidence reports, Dr. Gray drives the science behind all our work.

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Breast Cancer Endpoints

Even when chemicals are tested for safety, they aren't always tested for their impact on breast cancer risk. Without this critical link, advocates and the government lack important information for taking action to protect public health.

No evidence doesn't mean no risk. While our State of the Evidence report lists all the chemicals we know are linked to breast cancer, there may be many more we don't know about...yet.

This knowledge gap is partly due to inadequate screening of chemicals. Of the approximately 85,000 synthetic chemicals registered in the United States, only seven percent have been fully tested for their health effects[1]. In addition, most toxicological testing does not assess the effects of chemicals on the mammary gland, and typical methods do not look at early-life exposures, leaving significant data gaps in our knowledge about chemicals linked to breast cancer.

A recent meeting of experts in the field found that mammary gland changes may be the most sensitive measure of the adverse health effects of exposure to some endocrine-disrupting compounds[2]. These experts called for the development of more consistent methods to assess mammary gland development, and for the integration of mammary gland endpoints at critical windows of development into chemical test guidelines and risk assessment.

Research on mammary endpoints will become ever more critical as the search intensifies for alternatives to chemicals we know are harmful. Replacing a known risk with an unknown doesn't get us closer to our goal of preventing breast cancer.

We're monitoring a few emerging chemicals of concern. As more data becomes available, we'll update these and consider new additions.

  1. Bennett M, Davis BJ (2002). The identification of mammary carcinogens in rodent bioassays. Environ Mol Mutagenesis, 39:150-157.
  2. Rudel RA, Fenton SE, Ackerman JM, Euling SY, Makris SL (2011). Environmental Exposures and Mammary Gland Development: State of the Science, Public Health Implications, and Research Recommendations. Environ Health Perspect 119(8): 1053-1061. doi:10.1289/ehp.1002864