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Breast Cancer & The Environment

“Our genes give us the gun and we pull the trigger.”

Genetics (the gun) is critical, but so is our environment (the trigger). Most cases of breast cancer occur in women who are born with healthy genes but acquire the disease as a result of things they are exposed to in their lifetimes. Evidence indicates that there is a connection between our exposure to toxins in the environment and breast cancer.


There are over 85,000 synthetic chemicals on the market today, from carcinogens in our nail polish to flame retardants in our sofas, from plasticizers in our water bottles to pesticides on our fruits and vegetables. Currently, the U.S. government has no adequate chemical regulation policy, which allows companies to manufacture and use chemicals without ever establishing their safety in humans. Just as the use of chemicals has risen in the U.S. and other industrialized countries, so have rates of breast and other cancers.

Research shows that women who work as nurses, doctors, school teachers, and those who work with higher electromagnetic fields all have increased risk for breast cancer.

Women exposed to artificial light during night-time hours, especially night shift workers, experience a higher incidence of breast cancer than other women. Scientists believe light impacts melatonin, a hormone that helps prevent tumor formation, possibly explaining the association. The body produces high amounts of melatonin at night, and melatonin levels drop in the presence of light. So less sleep and disrupted sleep equals less melatonin. In 2007, the International Agency for Research on Cancer concluded that shift work is “probably carcinogenic to humans,” based on the associations between night-shift work and increased incidence of breast cancer.

The above is an excerpt from a documentary film with Olivia Newton-John called Exposure: The Environmental Links to Breast Cancer on early work in breast cancer prevention that is still relevant today. Since pioneering work in 1993 where Dr. Davis and colleagues introduced the term “xeno-estrogens” into the scientific lexicon (Davis et al., 1993), there has been a tremendous growth of activities in both the scientific and breast cancer prevention communities.

These are synthetic or natural chemical compounds which have estrogenic effects on a living organism. They mimic estrogen. Many scientific studies have found hard evidence of adverse effects on human and animal health such as early puberty, significant reproductive system alterations in males and females and increased cancers. Examples include Atrazine, BPA, DDT, Dioxin, Endosulfan, PCBs, Phthalates, and DDT. The elevated incidence of breast cancer in women has been associated with prolonged exposure to high levels of estrogens and, as we would expect, research shows xenoestrogens which mimic estrogen are associated with higher breast cancer incidence as well.

In the February 2015 “National Report on Human Exposure to Environmental Chemicals,” the CDC reports that the average person in the United States has over 265 chemicals in their blood and urine. In our daily life, we are exposed to many xenoestrogens. The effect on our body is cumulative, increasing our total body burden.

What is Body Burden?

Body burden refers to the total accumulation of these toxins in our body.  Our body has self-cleansing mechanisms, but if we expose ourselves to more toxins than our body can eliminate, they will accumulate in our fatty tissue and organs. The greater the accumulation, the greater the stress on our health.

Current government safeguards only look at one chemical at a time rather than our body burden from our cumulative exposure to chemicals and radiation in our environment.

Prevention or Cure?

President Clinton created the National Action Plan on breast cancer and the Department of Defense program on breast cancer that at one point involved $500 million in annual funding for research on this then neglected disease in the 1990s. Since then, major progress has been made in identifying inherited or acquired genetic risk factors and advancing treatment for certain types of breast cancer.

Unfortunately, most money has been spent on finding and treating the disease. Around the world, we lack comprehensive national programs to control, reduce, restrict, or eliminate environmental factors known to increase the risk of breast cancer.[/su_spoiler]

What can I do to reduce my risk?

Prevention is the best medicine. Simple changes in our lifestyle and consumer choices can significantly decrease our exposure to environmental toxins. Get informed, take it one step at a time, and share this information with your friends and family. Read Ten Things you Can Do To Prevent Cancer. Watch the informative videos on this page to learn more.

Equally important -if not more important- is calling on our government at every level to enact adequate safeguards when it comes to chemicals and radiation.


Dr. Davis’ submission to the Huffington Post – The Secret History of Mammography

Dr. Davis Commentary Are Potential Non-Celeb Breast Cancer Patients Priced Out Of Prevention And Treatment?

Freakonomics Devra Davis Responds to Your Cancer Questions

Environmental Issues and Breast Cancer: Ask the Experts Conference Q & A

Breast Cancer in Marines who were stationed at Camp Lejeune

Cornell University Bibliography Environmental Chemicals and Breast Cancer Risk – Why Is There Concern?

Collaborative on Health and the Environment Breast Cancer: Scientific References

NIEHS: Breast Cancer Risk and Environmental Factors

Silent Spring: Breast Cancer and the Environment

Shift work and chronic disease: the epidemiological evidence

For more information on preventing breast cancer please visit:
Scientific Publications/Dr. Devra Davis

Donovan M, Tiwary CM, Axelrod D, Sasco AJ, Jones L, Hajek R, Sauber E, Kuo J, Davis DL., Personal care products that contain estrogens or xenoestrogens may increase breast cancer risk. Med Hypotheses. 2007;68(4):756-66. Epub 2006 Nov 28.

Davis DL, Bradlow HL, Wolff MS, Woodruff T, Hoel G, and Anton-Culver H. Medical hypothesis: Xenoestrogens as preventable causes of breast cancer. Environ Health Perspect 1993; 101(5): 372-77.

Davis DL, and Love SM. Mammographic screening. J Am Med Assoc 1994; 271(2):152-53.

Bradlow HL, Davis DL, Gong l, Sepkovic DW, and Tiwari R. 1995. Effects of pesticides on the ratio of 16a/2-hydroxyestrone: A biological marker of breast cancer. Environ Health Prospect 1995; 103(Suppl7):147-150.

Davis DL, and Muir C. Estimating avoidable causes of cancer. Environ Health Perspect 1995; 103(Suppl8): 301-06.

Graphs on Age Specific Incidence for Female Invasive Breast Cancer for DCIS vs. LCIS by Race*:

Please click on the thumbnails below to view graphs.

Download Graph PDFs below.