Rates of thyroid cancer are well above the national average throughout the Philadelphia region.
But why?
They may be related to broader statistics that show high rates of many types of cancer in the Mid-Atlantic states, for reasons that scientists do not understand.
Or, some experts suggest, they may be the result of all the medicine practiced locally - more tests lead to more diagnoses.
Thyroid cancer also is found more often in older people, and more of them live here than in many other areas.
At a news conference yesterday, advocacy groups offered another possible explanation: proximity to nuclear power plants.
"This area has the greatest concentration of nuclear reactors in the United States," said Joseph J. Mangano, executive director of the Radiation and Public Health Project, based in Ocean City, N.J.
He referred to a circle that extended roughly 90 miles in all directions from the northwestern tip of Bucks County. Within it, he said, are seven nuclear plants and an "epidemic of thyroid cancer."
Mangano, who holds a master's degree in public health, published the results of his research in a small medical journal two months ago and booked the Mayor's Reception Room in City Hall for yesterday's news conference, which included several local environmental groups and cancer survivors.
But the city Health Department knew nothing about the event, and some other scientists dismissed him as a longtime crusader against nuclear energy who cherry-picked data to support his beliefs. Plus, they said, this kind of study cannot prove cause and effect, no matter how thorough it is.
"For example, you could look at rates of colon cancer and incidence of belief in Santa Claus," said Patricia Milligan, a health physicist and nuclear pharmacist at the Nuclear Regulatory Commission. There is a clear correlation - both are much higher in the United States than in Japan. But suggesting that Santa brings cancer down the chimney would be "ridiculous," she said.
Still, no one disputes the validity of Mangano's raw data, taken directly from the National Cancer Institute. Pennsylvania had the fourth-highest rate of thyroid cancer in the nation, about 2,000 cases, 42 percent above normal, in 2006, according to the most recent NCI statistics.
