Common Chemicals and Radiation 
Increase Breast Cancer Risk
UPdate spring 2005

A new report on environmental links to breast cancer concludes that exposure to synthetic chemicals and radiation has contributed more than previously thought to the rising incidence of breast cancer.

The report, "State of the Evidence 2004: What Is the Connection Between the Environment and Breast Cancer?" was released in October by two US groups, the Breast Cancer Fund, a non-profit environmental health organization, and Breast Cancer Action, a non-profit national education and advocacy organization.  

According to the report, fewer than one in 10 cases of breast cancer occurs in women born with a genetic predisposition for the disease. As many as 50 percent of breast cancer cases remain unexplained by personal characteristics and other traditionally accepted risk factors. Epidemiologists and other scientists increasingly believe many cases are linked to environmental factors.
Among the new research findings reported:

 •   Chlorinated chemicals, found in drinking water and many industrial processes such as computer component manufacturing, were associated with an elevated risk of breast cancer in three new studies;
 •   A solvent used in many varnishes, paints, dyes and fuel additives (ethylene glycol methyl ether) was found to sensitize breast tissue cells to the effects of estrogens and progestins, thereby increasing the risk of breast cancer and;
 •   The Million Women Study in the United Kingdom revealed that all types of post menopausal hormone replacement therapy (HRT) significantly increased the risk of breast cancer. This reinforced  earlier findings from the Women's Health Initiative study in the United States. Another study found that use of HRT by women previously diagnosed with breast cancer tripled a woman's risk of recurrence or development of a new breast tumor.

Barbara Brenner, executive director of Breast Cancer Action, said, "We need to take action to promote public policy that will reduce and eventually eliminate our exposures to toxic chemicals in the air we breathe, the water we drink and the food we eat."

In the past fifty years, a woman's lifetime risk of breast cancer has more than tripled in North America, to one in seven today. This trend parallels a staggering increase of chemicals in the environment. State of the Evidence 2004 says that "compelling scientific evidence" points to some of the 85,000 synthetic chemicals in use today as contributing to breast cancer by altering hormone function or gene expression.
"This new report offers the clearest evidence yet that the rise in breast cancer incidence is linked to exposure to radiation and toxic chemicals," said Nancy Evans, a health science consultant for the Breast Cancer Fund and the editor of the report. "Medical X-rays, pesticides, household cleaning products, personal care products and some pharmaceuticals-these are just a few of the multiple and chronic exposures contributing to this epidemic."

The report details how exposure to certain common chemicals known to increase the risk of breast cancer occurs often in the home and the workplace. These chemicals, known as xenoestrogens because they mimic or act like estrogens in the body, include: Bisphenol-A, used in plastic food containers and baby bottles; polyvinyl chloride (PVC), used extensively in food packaging, as well as in medical products, appliances, cars, toys, credit cards and rainwear; pesticides used on lawns and in commercial agriculture; and diethylstilbestrol, a drug prescribed for millions of pregnant women from 1941 to 1971 that doubled the risk of breast cancer for women who were exposed to it in the womb and who are now over 40.

State of the Evidence 2004 also highlights the effects of exposure to ionizing radiation, the best-established cause of breast cancer.  Dramatic increases in radiation exposure from X-rays, CT scans, fluoroscopy, nuclear fallout and other sources may have contributed to a rising incidence of breast cancer between 1950 and 1991, the report says. During this period, the incidence of breast cancer in the United States increased by 90 percent.

This third edition of the report amasses new evidence from 21 research studies published since February 2003, adding to existing evidence linking toxicants in the environment to breast cancer.  The new report was peer-reviewed by six leading scientists, including a noted scientist from the International Agency for Research on Cancer, a division of the World Health Organization.
The new report offers recommendations to help reduce the risk of breast cancer and ultimately end the epidemic, including: 

 •  Phase out chemicals known to cause cancer or genetic harm and test all others to determine the effects on human health and the environment;
 •  Hold corporations accountable for hazardous practices and offer incentives for clean, green practices;
 •  Educate the public about the health effects of radiation and how to reduce their exposure and;
 •  Establish a comprehensive biomonitoring program to measure the presence of chemicals in people and track resultant health outcomes.