State of the Evidence: What Is the Connection between Chemicals & Breast Cancer?

The Breast Cancer Fund and Breast Cancer Action
edited by Nancy Evans

EXECUTIVE SUMMARY
Breast cancer rates have been climbing steadily in the United States and other industrialized countries since the 1940s. Billions of dollars have been spent in an effort to stem this unrelenting tide, yet more than 50 percent of breast cancer cases remain unexplained by the characteristics and risk factors associated with the disease.

Ionizing radiation is the only proven environmental cause of human breast cancer. But powerful circumstantial evidence indicates that some of the 85,000 synthetic chemicals in use today are responsible for many of the unexplained cases of the disease. While scientists have not yet developed an ideal method for linking chemical exposures to breast cancer, several types of research – experimental, body burden and ecological studies – provide strong evidence of the connection between chemicals and breast cancer.

Because the types of evidence vary, the strength of the evidence linking chemicals and breast cancer also varies. The strongest evidence linking chemicals to breast cancer – based on the fact that lifetime exposure to natural estrogens increases the risk of breast cancer – concerns natural and synthetic estrogens, including drugs like diethylstilbestrol (DES), plastic additives like bisphenol-A (BPA), polyvinyl chloride (PVC) (found in many consumer products), dieldrin and some pesticides. Other synthetic substances strongly linked to breast cancer through experimental evidence are organic solvents (used in many manufacturing processes, including the manufacture of computer components), polycyclic aromatic hydrocarbons (PAHs) (created in soot and fumes from burning diesel, fuels or cigarettes) and 1,3 butadiene (a by-product of internal combustion engines).

There are also chemicals for which the evidence indicates a probable but less certain link to breast cancer. These chemicals include dioxin (created when plastics or other materials containing chlorine are burned), the pesticide DDT (dichloro-diphenyl-trichloroethane) and its metabolite DDE, and PCBs (polychlorinated biphenyls), previously used in the manufacture of electrical equipment and other industrial and consumer products.

Finally, there is evidence of chemicals that affect how the body functions in ways that suggest a possible link between these substances and breast cancer. These chemicals include the insecticide heptachlor and phthalates, used to make plastic soft and flexible.

We clearly have major gaps in our current knowledge about the links between breast cancer and the environment. Therefore, we need to focus our research efforts in areas that are most likely to provide useful information for framing public policies related to chemical exposures and our health. The types of research most likely to produce useful evidence will be those examining (1) workplace exposures, (2) household exposures and (3) breast milk as a marker for human contamination.

While we pursue the research that will lead to more definitive answers, the existing evidence linking chemicals to breast cancer demands that we act now as a society to begin removing many of these substances from our environment. Considerable resources are spent encouraging women to make changes in their personal lives in an effort to reduce their risk of breast cancer. But breast cancer is not just a personal tragedy; it is a public health crisis that demands action by society as a whole.

This crisis must be addressed by beginning now to implement the precautionary principle. Under this principle, evidence of harm, rather than definitive proof of harm, is the trigger for policy action. In addition, the precautionary principle mandates that the burden of proof with regard to chemicals rests with the manufacturers to demonstrate that the substances are safe, rather than with the public to show that they are harmful. Finally, the precautionary principle rests on the democratic principle that government officials are obligated to serve the public’s interest in human health and environmental protection.

The following 5-point plan will help us reduce the risk of breast cancer and ultimately end the epidemic:

1. PHASE OUT TOXIC CHEMICALS that are omnipresent in the lives of so many people.
2. ENACT “SUNSHINE” LAWS AND ENFORCE EXISTING ENVIRONMENTAL PROTECTION LAWS to reduce the use of toxics by requiring companies to report how many tons of chemicals they use.
3. PRACTICE HEALTHY PURCHASING, with local, state and federal governments leading the way in purchasing environmentally preferable products, thereby creating an example for individuals to follow.
4. OFFER CORPORATE INCENTIVES that encourage businesses to eliminate the use of harmful chemicals in their products and processes.
5. MONITOR BREAST MILK through a comprehensive community program that identifies the chemicals present in breast milk, establishes links to geographic areas and initiates a plan to eliminate these contaminants.

We ignore at our peril the increasing evidence that chemicals are contributing to the rising tide of breast cancer. The obligation to understand this evidence, and begin to address it through the implementation of public policies that put health first, rests with all of us. It is in our power to change the course we are on. Now is the time.

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Synergistic Effects of Toxic Metals (Mercury, Lead, Aluminum) Are Extreme

Bernard Windham, MD

Mercury and lead are extremely neurotoxic and cytotoxic, but their combined synergistic effect is much worse. A dose of mercury sufficient to kill 1% of tested rats, when combined with a dose of lead sufficient to kill less than 1% of rats, resulted in killing 100% of rats tested(1). Thus with combined exposure, the safe dose is 1/100 as much as the dose individually. Studies in Australia have confirmed similar relationships hold for people. This means most people in the US are getting dangerous levels of these metals, enough to cause some neurologic effects.

Similar is true for synergistic effect with other toxic metals like arsenic, and with other toxic chemicals like PCBs(2). The level of mercury thimerosal in vaccines has been shown to be highly neurotoxic, but the effect was found to be much larger due to the synergistic effect with aluminum, which is also in most vaccines(3). Studies using US CDC data have found thimerosal from vaccines to be major factors in autism and ADHD(4), along with prenatal rhogam shots which contain high levels of mercury thimerosal and are given to some RH negative women during pregnancy.

Autism has increased in the US more than 10-fold in the last decade. According to the Florida Department of Education, the numbers increased from approximately 300 to over 4000 during this time period. There have likewise been large increases in the number of children with ADHD and other developmental conditions, according to the National Academy of Sciences and other sources. A major factor in this appears to be the large increase in vaccinations given to infants. (more documentation is available at the childrens neurological page, www.home.earthlink.net/~berniew1/indexk.html)

There was an increase of over 45% in learning disabilities in Pennsylvania between 1990 and 2000(5). But the study showed that the county highest on the Chemical Pollution Scorecard, Montgomery, had an increase more than double that of the rest of the state. Montgomery County had an increase in ADHD of 32.7% and an increase in autism of 310%.

ps. note that a high percentage of Gulf state residents have been documented to have high levels of mercury exposure (Mobile Register study, www.home.earthlink.net/~berniew1/flhg.html)

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1. Schubert J, Riley EJ, Tyler SA. Combined effects in toxicology. A rapid systematic testing procedure: cadmium, mercury, and lead. Toxicol Environ Health 1978;4(5/6):763-776.

2. Philippe Grandjean P, White RF et al. Neurobehavioral deficits associated with PCB in 7-year-old children prenatally exposed to seafood neurotoxicants. Neurotoxicology and Teratology 2001;223(4):305-317.

3. Haley, BE, Pendergrass JC, Lovell, M, Univ. of Kentucky Chemistry Dept., paper presented to the Institute of Medicine Immunization Safety Review Committee, Spring 2001, and on medical lab website, www.altcorp.com

4. Pennsylvania Dept. of Education, 2003, Study of learning disability incidence in Montgomery County, Pennsylvania, 1990 and 2000; & ” Polluting Our Future: Chemical Emissions in the U.S. that Affect Child Development and Learning,” by Physicians For Social Responsibility, at (202) 898-0150, psrnatl@psr.org

5. Geier M.R., Geier DA; Thimerosal in Childhood Vaccines, Neurodevelopmental Disorders, and Heart Disease in the U.S. ; J of Amer Physicians and Surgeons, Vol 8(1), Spring 2003; & Bradstreet J, Geier DA, et al, A case control study of mercury burden in children with Autisitic Spectrum Disorders, J of Amer Physicians and Surgeons, Vol 8(3), Summer 2003.