Screening for Chemical Contributions to Breast Cancer Risk

A study published June 2nd, 2015 in Environmental Health Perspectives, “Screening for Chemical Contributions to Breast Cancer Risk: A Case Study for Chemical Safety Evaluation” outlines a new method for assessing how synthetic chemicals and pollutants may contribute to breast cancer risk. In addition to developing the chemical testing approach, the authors, including Janet Ackerman and Ruthann Rudel of Silent Spring Institute, identify two critical needs: the need for new chemical safety testing methods, and the need to screen more chemicals.

Inherited genes only explain about a quarter of a woman’s risk of developing breast cancer.  Exposure to synthetic chemicals and pollutants in air, water, food, workplaces, and consumer products may account for a significant portion of breast cancer risk.

Over 34 million tons of synthetic chemicals are produced or imported into the U.S. every year, and hundreds of these chemicals are commonly found in women’s blood, urine, and breast tissue. While most ​of these chemicals ​have not been tested for their carcinogenic potential, among those that have, hundreds increase mammary tumors in laboratory animals. Animal tests, however, rarely evaluate the effects of chemical exposure during early life or prenatal development.

​This study presents three important conclusions:

  • First, both genotoxicity (a chemical’s ability to damage genetic information in a cell) and endocrine disruption (interfering with normal hormonal activity) are significant contributors to breast cancer potential. Any comprehensive chemical assessment must evaluate both categories of biological mechanisms.
  • Second, while useful test methods exist for evaluating chemicals’ genotoxicity and estrogen-like activity, there are insufficient methods for testing a ​chemical​’s​ effect on other biological processes relevant to breast cancer, including progesterone activity.
  • Finally, there are large gaps in available test data even for chemicals generally thought of as “​well-tested.”

“The basic question is, what would you need to know about a chemical to be able to say with confidence that it doesn’t raise the risk of breast cancer?” said Megan Schwarzman, a physician and environmental health researcher at University California, Berkeley and the lead author of the study.

The authors concluded that new test methods are needed to effectively evaluate chemical risks. “Developing rapid, inexpensive chemical tests to fill the gaps identified in this study will make it easier for manufacturers to choose safer chemicals for consumer products,” said Ruthann Rudel, a toxicologist at Silent Spring Institute and a co-author of the study.

“There are so many places we can use this information today – regulators can consider requiring these recommended tests now; manufacturers can choose to use chemicals that pass these tests; and consumers can request that their suppliers use products that have undergone these tests​,” said Mhel Kavanaugh-Lynch, director of the California Breast Cancer Research Program, which funded this study.

Schwarzman states, “We’re actively trying to use the results to change how chemicals are tested and the decisions that are made in public policy. We see the potential for chemical testing to contribute to breast cancer prevention efforts.”

Beyond contributing to the identification of breast carcinogens, the authors hope that the methods they developed can be applied to other diseases, such as other cancers or neurological disorders that may be affected by chemical exposure.

During the Massachusetts Breast Cancer Coalition’s (MBCC) Let’s Talk Prevention: Reducing Toxic Exposures educational tour and other educational forums, MBCC is often asked if there is a connection between toxic chemical exposure and breast cancer.  We are asked where is the peer reviewed information.

​​Here it is.

Since Silent Spring Institute (SSI) was founded in 1994 by MBCC, SSI has been conducting and publishing critical, impactful research to determine the link between toxic synthetic chemical exposure and the risk of breast cancer and other hormone dependent and environmentally linked diseases.

This paper is an important step forward for the ongoing project of connecting breast cancer etiology with chemical testing and developing relevant testing programs. It details the mechanisms and endpoints that chemical testing programs need to include if they are to help prevent breast cancer; ​identifies which tests are available for these endpoints​; and highlights the gaps in both the availability of tests for some endpoints and ​the data for many chemicals.

The 2008-09 Annual Report of the President’s Cancer Panel was particularly concerned to find that the “true burden of environmentally induced cancer has been grossly underestimated.”  This is especially important for pregnant women and children, as some of the most vulnerable segments of our population. The rates of morbidity and mortality from cancer are at epidemic levels. Environmental injustices invade our neighborhoods, our bodies, and the well-being of our ecosystem. The lifetime risk of breast cancer was 1 in 20 in 1964, 1 in 14 in 1984, and today the burden is 1 in 8.  Our government has spent billions of our dollars on the “war on cancer,” and yet breast cancer rates have more than doubled in the last 60 years.

The time to act and to protect our families and future generations is now.  This study is a clear, definite, correct step in the right direction but policy progress is slow and incremental. When Toxic Substances Control Act (TSCA) was passed in 1976, over 65,000 chemicals were “grandfathered in” and remained on the market without full safety testing. Today, out of over 84,000 chemicals registered for use, only about 200 have been adequately tested.

​Additionally, only 5 ​c​hemicals have been restricted under TSCA. We cannot proceed at a “product by product” pace as the rate of chronic diseases and health care costs rise and rise.

MBCC hopes this new method to assess synthetic chemicals will aid to phase out and replace known carcinogens, genetic mutations, hormone disrupters, and reproductive toxins in a very timely manner.  We want a reformed, strengthened, and enforced Toxic Substances Control Act so we can move forward with safer choices. We want a future where public health, ecosystem health, and the health of future generations are a priority.

MBCC is advocating to help further reduce our exposure to chemicals of concerns, and ensure that from the manufacturing floor to the store shelves, we are confident in the products we purchase, the water that we drink, and the food that we eat to be contaminant free. Demand is building for a world in which toxic chemicals are not found in our homes, workplaces, schools, playgrounds, and everyday products on sale at the corner store.

MBCC recommends a systemic paradigm shift in thinking and acting to change breast cancer prevention to the Precautionary Principle. If there is indication of harm, we ask that chemicals be pragmatically replaced. We ask that the manufacturing, transportation, and use of chemicals have higher environmental standards. We look for a future where infants do not carry a burden of hazardous industrial chemicals passed along through their umbilical cord. We seek a future free from the ball and chain of diseases such as breast cancer.

Study information:

Schwarzman MR, Ackerman JM, Dairkee SH, Fenton SE, Johnson D, Navarro KM, Osborne G, Rudel RA, Solomon GM, Zeise L, Janssen S. 2015. Screening for chemical contributions to breast cancer risk:  A case study for chemical safety evaluation. Environmental Health Perspectives. DOI: 10.1289/ehp.1408337