Are manmade chemicals boosting breast cancer rates?
Maureen Coulter was 38 when she began to notice the symptoms: dizziness,
headaches and shortness of breath. Over the next two years, the Halifax nurse developed multiple allergies and frequent respiratory infections—the result, she believes, of an environmental illness caused by airborne pollutants at the hospital where she worked. By June, 1992, she had to stop working. “I couldn’t think clearly, I couldn’t breathe,” she recalls. Only three months later, Coulter discovered a lump in her breast—diagnosed later as cancer. “The cancer could be the end result of all that happening to me,” says Coulter, a mother of two who underwent a lumpectomy, chemotherapy and radiation therapy for the disease. “I can’t say it was the cause, but I feel it was certainly a factor.”
It is an increasingly familiar refrain among survivors and activists: that environmental factors—from pesticides and household products to the air people breathe—may have something to do with the high incidence of breast cancer in the Western world. Statistics certainly leave open that possibility. From 1960 to 1995, the lifetime risk of breast cancer in industrialized countries has risen from 1 in 20 women to about 1 in 9—an increase in part owing to better reporting and diagnosis procedures. Equally compelling, perhaps, is that the established risk factors for breast cancer—heredity, early-onset men-
struation, late entry into menopause, and delaying childbirth past age 30—account for only about a third of all cases. Mary O’Brien, a gerontologist at Mount Saint Vincent University who in mid-March organized a Halifax workshop on breast cancer and the environment, asks: ‘What’s happening to the other 70 per cent of women?”
Trying to answer that, some researchers have focused on a possible link between breast cancer and organochlorines—chemicals used in some plastics, dry cleaning fluids, refrigeration fluids and pesticides like DDT. In 1993, Mary Wolff, a researcher at the Mount Sinai Medical Center in New York City, found that women with the highest levels of DDE—a byproduct of DDT—in their bloodstreams were four times more likely to develop breast cancer than those with the lowest levels. Another study, led by Dr. Eric Dewailly of Laval University in Quebec City, concluded that the breast tissue of women with certain types of breast cancer had higher concentrations of DDE and of PCBs than cancer-free women.
One widely held theory links breast cancer to esg trogen, the hormone largely responsible for female g sexual development. The suspect organochlorines 2 might promote cancer by mimicking natural estro£ gen, or by changing the way the body processes the I hormone. Devra Lee Davis and Leon Bradlow, re1 searchers at New York’s Strang-Cornell Cancer ^
Research Laboratory, suggest that organochlorines 8 may enhance production of so-called bad estrogen, which has been found at elevated levels in cancerous breast tissue.
Dr. Ana Soto, a researcher at Tufts University in Massachusetts, began studying the effects of estrogen-mimicking chemicals—or xenoestrogens—in 1987, after she discovered that plastic tubing, used during a lab experiment, had caused breast cancer cells to grow as if they had been exposed to estrogen. Since then, Soto says that her team has identified xenoestrogens, including bisphenol-A and phthalates, in a host of common products—from plastics and detergents to the lining of aluminum cans. The body, Soto adds, seems able to process the xenoestrogens less efficiently than it can natural estrogen. “They also accumulate in fat, and we have no idea how long it takes the body to eliminate them,” she says. Soto is conducting a
long-term study into breast cancer and xenoestrogens, but contends there is already enough evidence to ban such compounds.
But other experts are not so sure. Donna Houghton, a toxicology researcher at the University of Guelph in Ontario, recently published a review of more than 100 studies on the link between organochlorines and breast cancer and found them inconclusive. “When you put all these things together—breast cancer, declining sperm counts—it
seems to be suggestive,” she adds. “But the science doesn’t support it.” Leonard Ritter, executive director of the Canadian Network e?f Toxicology Centres, points out that now-banned DDT functions as an “extremely weak” estrogen. “I think it’s very unlikely that it is going to turn out to be an important contributor to the overall incidence of the disease,” he says.
Still, Ritter and other health-care officials say the evidence so far warrants further study. In fact, the federal government, the Canadian Cancer Society and the National Cancer Institute (NCI) are funding two major studies into organochlorines and breast cancer, now being conducted by Laval’s Dewailly and by Kristan Aronson of Queen’s University in Kingston, Ont. Dr. Elizabeth Kaegi, director of medical affairs and cancer control for the Canadian Cancer Society and the NCI, cautions that a number of other possible risk factors—dietary fat, the role of exercise, and obesity in early womanhood—have also been linked to breast cancer. ‘We need to try and unscramble the relative roles of each of these factors,” says Kaegi.
Maureen Coulter does not want to wait for research to confirm what she already believes about a disease that killed almost 6,000 Canadian women last year. In late 1994, she and a handful of other women founded Breast Cancer Action Nova Scotia—a group, like dozens of other activist networks across the country, formed partly to press for action against pollutants. “It’s a big political issue—to start looking at the society you live in that might be making people sick,” says Coulter. “But I think governments have to address it, and people have to put pressure on governments to do it. We’re trying.”
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