01.08.2010 Naturopathy

Toxins and Breast Cancer

Naturopath Narelle Stegehuis explores the growing evidence of a link between environmental toxins, particularly heavy metals and xenoestrogens, and breast cancer

Toxicity is rampant. As our environment becomes more toxic, our bodies absorb more toxins through our skin, the food we eat and the air we breathe. Studies have shown that even babies have high levels of toxins in their bodies, having been transferred through the placenta. Our bodies work hard to eliminate toxins through the skin, kidneys, liver and exhaled air.

Toxicity can be a major cause of hormonal imbalances, cancer, thyroid problems, neurological disturbances, learning problems, depression, skin disorders and allergies.

The role of estrogen in many breast cancers is well established. Breast cancer results from the abnormal growth of cells in the mammary gland. The development of the mammary gland is regulated by estrogen, a hormone that binds to the estrogen receptor (ER). Most breast cancer cases initially develop as hormone-dependent cancer, in which growth and progression of the disease correlates with estrogen levels.

Research conducted by Ana Soto et al at Tufts University School of Medicine looked at the control of breast cancer cell proliferation. (1). They determined that estrogen does not directly cause breast cancer cells to proliferate, but, instead, it blocks the action of an inhibitor. With the inhibitor blocked, the cancer cells are then able to proliferate.

Dr Maggie Louie, Assistant Professor in the Department of Natural Sciences at the Dominican University of California has found that environmental contaminants do play a role in the development of breast cancer. Her preliminary findings not only show that the heavy metal cadmium promotes breast cancer cell growth, but her lab may have also identified a potential pathway for its action.

"My current research is focused on understanding the mechanism of how hormone-refractory breast cancer develops," says Louie. "One potential mechanism may involve endocrine disruptors including heavy metals such as cadmium." An endocrine disruptor is a synthetic chemical that, when absorbed into the body, either mimics or blocks hormones and disrupts the body's normal functions.

Many of the toxins in our environment are classified as xenoestrogens or metalloestrogens, that is, they mimic estrogen and are therefore considered harmful and potentially linked to breast cancer.


Xenoestrogens are compounds that have been introduced over the past 70 years or so in manufacturing and industrial processes. They are widespread in society; some possible sources are plastics, detergents, personal care products, pesticides, fertilisers, spermicides, the coating inside food cans and hormones used to fatten animals for meat production. Some of these xenoestrogens may be stored in the body for decades, having a cumulative effect.

The effect of xenoestrogens on breast cancer cell proliferation was discovered by accident at Tufts University. Soto's research identified contamination from plastic tubes as having an estrogenic effect - breast cancer cells were proliferating in the absence of estrogen, when normally they wouldn't. This was puzzling until the researchers identified the estrogenic effect was being caused by chemicals were being leached from new plastic tubes.

In addition to the possibility of contributing to breast cancer, xenoestrogens can upset the body's hormonal balance causing symptoms of estrogen dominance and reproductive disorders, such as fibroids, PMS, endometriosis and PCOS.


Heavy metals become toxic when they are not metabolised by the body and accumulate in the soft tissues, kidneys and liver. Heavy metals may enter the body through food, water, air or absorption through the skin in agricultural, manufacturing, pharmaceutical, industrial, or residential settings.

Research conducted by the School of Biological Sciences at the University of Reading (2) has identified a class of metals called metalloestrogens. These metals have the potential to add to the estrogenic burden of the human breast by mimicking estrogen and activating receptors. Metalloestrogens that have been identified include aluminium, antimony, arsenite, barium, cadmium, chromium (Cr (II)), cobalt, copper, lead, mercury, nickel, selenite, tin and vanadate.

Sources of aluminium toxicity include aluminium cooking utensils, food additives (eg sodium aluminium phosphate used as a raising agent), antiperspirants, medicines, air, water and food and drink packaging. In a 2005 study conducted at the University of Reading, aluminium in antiperspirants was found to be linked to breast cancer by its ability to interfere with the function of estrogen receptors. It is especially important to never apply antiperspirant to broken skin eg after shaving underarms.

Aluminium is also known to damage genetic material and act as a neurotoxin, contributing to mood disorders (depression and anxiety) and Alzheimer's disease.

Cadmium is used in batteries, PVC plastics and paint pigments. It can be found in soils because insecticides, fungicides, sludge, and commercial fertilisers that contain cadmium are used in agriculture. Cadmium may also be found in shellfish from reservoirs containing high levels of cadmium from environmental pollution.

Cigarettes are a major source of cadmium toxicity. Lesser known sources of exposure are dental alloys, electroplating, motor oil and exhaust fumes.

Sources of mercury toxicity include amalgam fillings and contaminated seafood. Amalgam fillings may leach mercury when hot drinks are consumed or through brushing teeth. But particular care must be taken if replacing fillings, as a higher level of mercury may be absorbed. Mercury also accumulates in large, longer-lived fish such as shark, swordfish, tuna and mackerel.

Other non-seafood sources of omega 3 fatty acids are English walnuts, flax oil, flax seed (ground), hemp oil, olive oil, leafy green vegetables (small amounts, but a good omega 3 to omega 6 ratio) and pumpkin seeds.

The data suggests that gradual accumulation of heavy metals in the breast tissue may be closely related to breast cancer growth. Evaluation of metal exposure through hair analysis tests and subsequent chelation treatment may be needed to prevent and treat metal-related breast cancer.

The etiology of the majority of human breast cancers is still controversial. However, hormonal influences and environmental toxic compounds have been suggested to play a role in breast cancer. Breast cancer is only one of the possible effects of xenoestrogens and metalloestrogens. As they mimic estrogen, they can disrupt the hormonal balance in the body and cause other problems related to hormonal imbalance, such as fibroids, PMS, endometriosis and PCOS.

(1) ENVIRONMENTAL HEALTH PERSPECTIVES (Anderson HR, et al., "Comparison of short-term estrogenicity tests for identification of hormone-disrupting chemicals," 107:89-108, Suppl. 1, February 1999)
(2) JOURNAL OF APPLIED TOXICOLOGY J. Appl. Toxicol. 2006; 26: 191-197

Narelle Stegehuis is a naturopath and recent recipient of the Australian Naturopathic Excellence Award who specialises in the treatment of women's health. Uniquely her services are offered online through www.massattack.com.au or www.bumpfertility.com.au