Environmental Links to Breast Cancer
Breast cancer is the most common cancer among Canadian women, excluding non-melanoma skin cancer, and continues to be a concern for every woman that I encounter in my practice. Upon learning that they are faced with a one in nine chance of developing breast cancer, many women have asked, "What can we do about this? What changes can we make in our daily lives to reduce our risk?" Unfortunately many risk factors are beyond our control. Our hereditary risk factors, reproductive risk factors (depending on age), age, and breast density are not things we can change. However some risk factors like lifestyle influences, exercise, body terrain, hormonal balance and our environment are things we can have an impact on. This article will review some of the chemicals are that linked to cancer and what we can do to minimize our exposure.
The list of chemicals that are linked to breast cancer is long, but I have chosen to focus on a few that are prevalent in our current environment: polychlorinated biphenols (PCBs), alcohol, dioxins, bisphenol-A(BPA), pesticides, phthalates, parabens, mercury, cadmium, and lead.
PCB's were used in electrical transformers and other products in the 1970's but have been banned in most industrialized countries for over ten years. Despite this ban they remain in human tissue as well as in our soil and water. Researchers found a two-to-four fold increase in breast cancer in women exposed to PCB's and the most consistent dietary predictor of PCB concentration in the breast was fish consumption.
Alcohol consumption has been linked to an increased risk of breast cancer in several studies. In one study, the risk increase was 250% for women who drank two or more drinks per day. The mechanism by which this occurs is still unclear. Alcohol may increase estrogen levels in the body or it may interfere with the body's ability to detoxify both chemicals and excess estrogen. Alcohol also increases the production of insulin-like growth factor which promote the development and/or growth of breast cancer tissue.
Dioxins are produced during the manufacturing and combustion of chlorine compounds. When products made from PVC plastic and PCBs are incinerated, dioxins are released into the air. They then make their way into the water, contaminate crops and end up in the food chain. Dioxins are known cancer causing agents, and there is some evidence that women with known exposure and high levels of dioxins in their body had a twofold increase risk of developing breast cancer.
Bisphenol-A (BPA) is a chemical found in hard plastic water bottles, the lining of tins cans and in dental materials. Since it was originally developed as a synthetic estrogen, it is no surprise that in laboratories BPA stimulates breast cancer cell growth, just like human estrogen.
The list of currently used pesticides that have a proven impact on breast health is overwhelming. Studies in laboratories show that pesticides such as DDT have an estrogenic effect. They cause breast cancer cells to grow and divide just like estrogen. This is most significant in estrogen receptor positive cancers. A study done in 2002 by the Windsor Regional Cancer Centre found that the incidence of breast cancer in women under age 55 who worked on farms was nine times higher than the average. Another report released in 2006 from the Long Island Breast Cancer Study Project showed that even women who used pesticides occasionally had an increased risk of breast cancer.
Phthalates are used in the plastics industry to make plastics soft and add flexibility. They are present in plastic wraps and packaging, plastic vinyl shower curtains and tablecloths, cosmetics and children's toys. They are known hormone mimickers and have been shown to increase breast cancer cell proliferation in the lab. Phthalates are abundant in the environment and accumulate in human tissue. They can also lower thyroid hormone and progesterone levels which can further contribute to PMS symptoms, breast cancer and miscarriages.
Parabens are another group of chemicals we are exposed to everyday. They are present in many personal care products like cosmetics, shampoos, lotions, and soaps. Parabens have been found within breast tumors and they have been found to act like estrogen in the body and cause breast cancer cells to grow and proliferate.
Heavy metals such as cadmium, lead and mercury are very common in our environment. Common mercury sources include fish and dental amalgams. Cadmium is present in some contaminated soil (and therefore food) and cigarette smoke. Lead is found most commonly in old homes with lead paint, lead pipes, ceramics and food grown in contaminated soil. Recently, it has been found in children's toys imported from China. The adverse health effects of all these metals are well known and the impact on breast health is no exception. Women with elevated cadmium levels had twice the risk for breast cancer than age-matched controls. Lead and mercury can stimulate breast cancer cells to grow and proliferate.
So what do we do about all these chemicals in our environment? The first steps are avoidance, avoidance, avoidance. See my Avoidance Action Plan below to reduce your exposure to chemicals that can increase your risk of breast cancer. The next step is detoxification. Work with our naturopathic doctors to find the best way to get these chemicals out of your body so you can minimize the impact they have on your health. We cannot control everything in our environment, but we can choose what products we use, where we spend our money, and which companies we support. Choose those companies that operate with your health, and the health of the planet, in mind.
Avoidance Action plan
- Eat fish no more than once per week and make sure your fish oil supplements are free from PCB's, heavy metals and other environmental contaminants.
- Drink less than two to three alcoholic beverages per week.
- Avoid using PVC and plastics. Do not purchase PVC blinds.
- Avoid storing food in plastic and drinking from plastic water bottles. If you eat canned food, choose from companies that are known to be BPA free (Eden, Vital Choice). Encourage your local grocer to be aware of this distinction and let them know you want to purchase from these companies.
- Eat organic food when possible. For more information on the most important foods to eat organic please see a previous article titled "Shoppers Guide to Pesticides in Produce".
- Avoid using pesticides on your garden and yard.
- Buy food, especially oils and fatty foods, in glass or paper rather than plastic containers.
- Use waxed paper or butcher paper to wrap sandwiches and other food.
- Do not microwave in plastic containers or plastic wrap.
- Choose paraben-free personal care products and cosmetics.
- Avoid eating fish high in mercury such as king mackerel, shark, swordfish, tilefish, bluefish, lobster, marlin, orange roughy, red snapper, bass (saltwater), trout (fresh water), tuna (fresh), tuna canned (white albacore).
- Quit smoking.
Sources and resources
- The Complete Natural Medicine Guide to Breast Cancer. Sat Dharam Kaur, ND. Robert Rose Inc. Toronto. 2003
- 8 weeks to Women's Wellness. Marianne Marchese, ND. Smart Publications. Petaluma, Ca. 2011.