San Francisco Chronicle

Tuesday, August 6th, 2002

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Bradley Angel Greenaction

(415) 248-5010

Breast cancer-toxics study finds weak link

Bay Area environmental activists are skeptical

Keay Davidson
Chronicle Science Writer

A long-awaited study of breast cancer and environmental toxics on Long Island by the National Cancer Institute has found only a weak correlation between cancer rates and one form of chemical exposure. The study, released today, drew a skeptical reaction from environmental activists concerned about purported breast cancer "clusters" elsewhere, including Marin County and other sites in the Bay Area.

The study is the largest to date that examines possible correlations between chemical exposure and breast cancer. For years, environmental activists have claimed that the United States is pockmarked with areas where cancers, including breast cancer, are unusually common.

Activists have argued that such high incidence rates may be due to local environmental toxics, such as chemicals and radiation from nuclear power plants.

On Long Island, investigators found the risk of breast cancer rose by a "modest" 50 percent among women who were exposed to polycyclic aromatic hydrocarbons (PAHs) and live in Suffolk and Nassau counties, according to the Long Island Breast Cancer Study Project, funded by the National Cancer Institute and the National Institute of Environmental Health Sciences.

The study was undertaken in response to a congressional order in 1993, following public protests over apparently high breast cancer rates in the New York suburbs.

A 50 percent rise in risk might not sound "modest" to laypeople. However, it is a minor increase "compared to other known risk factors for cancer," National Cancer Institute officials explained in a press statement released along with the study.

Smoking, for example, increases the risk of developing lung cancer by 900 percent to 1,000 percent, while a family history of breast cancer increases risk by 100 percent to 200 percent. Furthermore, even the apparent 50 percent increase in risk is only "marginally statistically significant," said Dr. Deborah Winn, head of the institute's division of cancer control and population sciences in Rockville, Md. She is the government official who oversees the project for the National Cancer Institute but did not take part in the research directly. Although the findings did show a statistically valid link between cancer rates and toxic exposure, the result was "just on the border," she said.

The study found no correlation between breast cancer rates on Long Island and exposure to another type of chemical, organochlorine compounds. PAHs come from air pollution (including auto and airplane exhausts), cigarette smoke, and grilled and smoked foods. Organochlorine compounds come from the pesticide DDT and industrial compounds, PCBs.

A study of 3,000 women was led by principal investigator Marilie D. Gammon, an associate professor of epidemiology at the University of North Carolina at Chapel Hill. The study investigators took blood samples from all the women and determined chemical levels in their blood. Then they tried to correlate levels of chemical exposure with whether the women had ever experienced breast cancer.

Technical details of the research are scheduled to appear in this month's issue of the journal Cancer Epidemiology, Biomarkers & Prevention. Gammon's colleagues in the study include 27 researchers at Columbia University, Cornell Medical Center in Ithaca, hospitals on Long Island, and other institutions.

The report upset some Bay Area activists.
"I don't believe it," said Bradley Angel, executive director of Greenaction,
a San Francisco organization that investigates health problems that are purportedly linked to pollution in communities across the Western United States, such as Hunters Point.

Angel grew up on Long Island, where his mother and a neighbor's mother died of breast cancer. "I cannot say that any one source killed my mother," he said in a phone interview Monday.

"But I can tell you that a woman (his mother) in her 30s should not be dying of breast cancer," Angel said. "And when that's happening to more than one person in a neighborhood, something is very wrong. I have no doubt that it was related to pollution in our environment," possibly pesticides from farming practices conducted before homes were built in the Long Island neighborhood.