Common Chemicals: Breast Cancer Link?

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Pesticides. Plastics. blood, cord sunburn before age 17 starts a process that can end up as a deadly melanoma skin cancer decades later.

The Role of Genetics

While every woman has at least the potential to succumb to environmental influences, not every one will. What makes the difference? Our genetics — the individual blueprint that governs how every cell in our body is supposed to act.

“Inside each cell is all our genetic material — the total number of genes from both parents,” says Smith. The genes that are “expressed,” she says, are those that we see — for example, blue or brown hair.

But what we see is only a small portion of our genetic makeup. Most of what is in our cells is “unexpressed” — including our risk for certain diseases.

And while there are some clear-cut genetic links to breast cancer that a woman can inherit, this group makes up a relatively small segment of the breast cancer population.

What is likely to affect many more of us, says Smith, is a genetic predisposition — a gene that is lying dormant in our body that, when awakened by some circumstance, increases the risk for breast cancer.

“Once the gene is aroused, it begins to express itself — and that expression can cause the kind of cellular changes that eventually lead to cancer,” says Smith.

Many believe that it is environmental exposures — including chemicals — that can awaken at least some of those dormant genes and put a woman on the cellular path to breast cancer.

Reducing Risks: What Women Can Do

While we can’t change our genetics, experts say we can, to some extent, control our environment.

And while you may be thinking this means avoiding carcinogens — chemicals known to cause cancer — experts say when it comes to breast cancer, of far greater concern is exposure to what are called “endocrine disrupters.” These are chemicals and byproducts that, when inhaled, ingested, or absorbed through the , can either mimic the effects of estrogen in the body or cause estrogen to act in a way that isn’t normal.

Since it is estrogen that can spark the growth of many tumors, Gray says anything that interferes with estrogen metabolism has the potential to cause harm.

“These chemicals cause a ‘triple whammy’ — they increase levels of estrogen, alter cell metabolism, and influence the pathways that increase the risk of cancer,” says Gray.

Antiperspirants and Breast Cancer

Based on a recent study in the Journal of Applied Toxicology, cancer researcher Philippa Darbre, PhD, of the University of Reading in England, says the evidence is mounting that the aluminum-based active ingredient in antiperspirants can mimic estrogen in the body.

At the same time, in a report released in 2004, officials with the National Cancer Institute wrote that there was “no conclusive research” linking the use of underarm antiperspirants or deodorants to breast cancer.

And the American Cancer Society (ACS) says that most research on environmental links to breast cancer remains unproven and that research linking deodorant use to breast cancer remains weak.

ACS spokeswoman Elizabeth Ward, PhD, previously told WebMD that there is not much evidence that any environmental exposure has a big impact on breast cancer risk. She points out that studies examining pesticides known to mimic estrogen have failed to show a link between exposure and breast cancer.

“This is a topic that is still under study, and it is important to study it further,” she says. “But no strong evidence has emerged of a relationship [between breast cancer risk] and exposure to environmental contaminants.”

Smith offers this advice: “You have to accept in life that there is a great deal we don’t know — and just stay as close as possible to a natural state of living. Cut down where and when you can and minimize risks when and where you can in all areas of your life.”

To help all women make more intelligent lifestyle, personal care, and environmental choices, Gray and her colleagues at Vassar and the University of Pittsburgh Cancer Institute have created an educational CD that can be requested via their web site (www.erbc.vassar.edu).

Additionally, the Environmental Working Group offers an online database of some 14,000 personal care products rated by their level of chemical contaminants.