A study that sought to explain the high rate of breast cancer on Long Island found no evidence to support fears that living near power lines causes the disease.
Researchers called the findings reassuring and said the study suggested they could rule out electromagnetic fields and focus on other risk factors for breast cancer, which strikes 200,000 women each year in the United States.
"All around, it is good news," said Dr. M. Cristina Leske, the lead researcher on the study, which is to be announced Wednesday and will appear in the July 1 issue of the American Journal of Epidemiology.
Exposure to invisible electromagnetic fields is nearly unavoidable in today's society. They are created wherever electricity is generated or used — near power lines and wiring, electrical equipment and appliances.
Stony Brook University launched the study in 1996, after earlier studies indicated a possible connection between electromagnetic fields and cancer. Researchers believed at the time that the fields might hamper production of the estrogen-related hormone melatonin.
The study examined 1,161 women on Long Island — 576 who had breast cancer and 585 who did not. Researchers took spot and 24-hour measurements of magnetic fields in often-used rooms in their houses, such as bedrooms and living rooms, and the study mapped the power lines surrounding each home.
They found no association between exposure to electromagnetic fields and breast cancer.
A previous study conducted in Seattle reached the same conclusion. But Stony Brook researchers included only women who had lived in their current home for 15 years — a better measure of the risk of long-term exposure.
The annual breast cancer case rate is about 115 per 100,000 women in Nassau County and about 118 per 100,000 in Suffolk County - the two counties that make up Long Island.
The national rate is about 104 per 100,000.
Suspicions that environmental factors — even something in the water — are behind "clusters" of high breast cancer rates have led to anti-cancer fund drives and public awareness campaigns.
But some scientists say the clusters have more to do with the people, not their surroundings. Studies have suggested breast cancer is more likely to strike women who have children late in life or take hormone supplements.
Major studies have failed to turn up significant links to environmental factors. A recent $8 million, seven-year National Center Institute study looked for pesticides in the blood and urine of people on Long Island and found no breast cancer link.
Geri Barish, president of One in Nine, a Long Island breast cancer advocacy group, said she was not surprised by the study's findings. But she said further studies should be conducted on the subject.
"I don't think anyone should be satisfied," she said. "I think we need to push on."