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Researchers have linked radiation releases from the Three Mile Island nuclear plant to higher cancer rates in nearby communities in a study that could reopen debate over the nation's worst commercial nuclear accident.
The report, released today, concludes that increases in lung cancer and leukemia near the Pennsylvania plant suggest a much greater release of radiation during the 1979 accident than had been believed.
Previous studies concluded that radiation exposure to humans was minimal. A 1990 Columbia University analysis using the same data as the new study found no clear connection between the accident and cancer rates among residents living near the plant.
"The cancer findings, along with studies of animals, plants and chromosomal damage in Three Mile Island area residents, all point to much higher radiation levels than were previously reported," said Steven Wing, an associate professor of epidemiology at the University of North Carolina and co-author of the study. "If you say there was no high radiation, then you are left with higher cancer rates . . . that are otherwise unexplainable."
The findings appear in today's edition of Environmental Health Perspectives, the journal of the U.S. National Institute of Environmental Health Science. In a letter accompanying the article, the Columbia University researchers who initially analyzed the cancer data disagreed sharply with Wing's conclusions and labeled the new study "tendentious and unbalanced."
"There are no new findings here, only a new interpretation," wrote Maureen Hatch of the Mount Sinai School of Medicine and two colleagues. "What leads two groups of epidemiologists to attach different meaning or give different emphasis to essentially the same data is a puzzle that is likely to to remain with us for as long as subjectivity plays a role in epidemiology."
The study comes a year after a federal judge dismissed damage claims by more than 2,000 neighbors of the Three Mile Island plant, citing a "paucity of proof" to support assertions that radiation from the accident affected their health.
Radioactive gas was released from Three Mile Island beginning on March 28, 1979, after a series of mistakes and mechanical failures led to a partial meltdown of the nuclear plant's radioactive core. The molten uranium was contained inside the reactor building, and the overall radiation exposure to nearby residents was described as low -- lower than most people receive from natural background sources.
Fears about health consequences from the accident were at least partly alleviated by the landmark 1990 Columbia study. Hatch and her colleagues tracked cancer rates from 1975 to 1985 among the 160,000 people who lived within 10 miles of the plant. They concluded that certain cancers -- notably lung cancer and leukemia -- were higher among people who lived downwind of the plant and had the greater risk of exposure to radioactive gas.
But the Columbia researchers found no correlation between presumed exposure and the development of the types of cancer normally associated with radiation. They concluded that other factors -- such as smoking or income levels -- accounted for the higher cancer rates. "The pattern of results does not provide convincing evidence that radiation releases . . . influenced cancer risk," the Columbia study said.
But Wing, in his report, said the Columbia results were skewed because of incomplete data or faulty analysis and didn't consider enough types of cancers.
Reports of low levels of radiation outside the plant didn't jibe with accounts of severe symptoms -- vomiting, diarrhea, hair loss, dying pets -- by some of the plant's neighbors, Wing said.
After re-running the data, he concluded that exposed neighbors suffered two to 10 times as many lung cancer and leukemia cases as those who lived upwind.
In Pennsylvania, activists who have been fighting the nuclear plant for nearly two decades viewed the new study as a vindication. "No one knows how much radiation escaped," said Eric Epstein, chairman of Three Mile Island Alert. "The study confirms what people have been reporting for 18 years."
But Theodore Rockwell, a Bethesda-based nuclear engineer and nuclear power proponent, accused the researchers of twisting the data to support their theory. "The same crowd of people keeps coming up with this stuff," Rockwell said, "but in all these years of trying to find a problem, they haven't been able to come up with one."