More than a million people exposed to fallout from the Chernobyl nuclear accident, inside the Soviet Union and elsewhere, will develop cancer, and about half will die, a University of California scientist and nuclear power critic said Tuesday.
Dr. John W. Gofman, professor emeritus of medical physics at UC Berkeley, predicted that 424,300 people in the Soviet Union and 526,700 elsewhere, including other parts of Europe, will develop cancer over the next 40 years as a result of the Chernobyl accident.
In a research paper presented Tuesday at a meeting of the American Chemical Society in Anaheim, Gofman predicted that 19,500 more can be expected to develop leukemia, while an unknown number of others will develop thyroid and other cancers.
Gofman, a physician and expert in the health effects of low-level radiation, has consistently estimated the cancer and death rate resulting from Chernobyl to be higher than other experts. He said Tuesday that recent projections of 5,000 to 24,000 Soviet deaths were grossly underestimated because of false assumptions about the minimal effect of low-level radiation.
Less than a month after the nuclear accident, Gofman estimated that at least 32,900 people in Scandinavia and the rest of Europe could develop cancer as a result of the accident and that about half of those could die.
Those calculations were based on "spotty" initial levels measured outside the Soviet Union after the fire and core meltdown. Extrapolated for the area within the U.S.S.R., Gofman also said last May that as many as 23,000 Soviet citizens eventually could die from radiation-induced cancer.
Estimates released Tuesday, which are more than 1,200 times greater, are based on more detailed reports of levels measured over longer periods.
His new estimates "certify Chernobyl as the worst accident in history," said Gofman, who worked on the Manhattan Project, developing the earliest atomic bombs during World War II.
"What this proves," he said, is that "there is no 'safe' dose of radiation" that does not carry with it a risk of causing cancer in humans.
David Harward, manager of environmental projects for the nuclear industry's Atomic Industrial Forum, responded Tuesday that Gofman's estimates were out of step with those of the "vast majority of" international radiation experts.
"This certainly does not agree with at least 99% of the rest of the scientific community," Harward said.
The Soviet Union has recorded 31 deaths from radiation exposure among workers at the Chernobyl plant, 60 miles north of Kiev in the Ukraine. An explosion and fire during the early morning hours of April 26 destroyed the 1,000-megawatt nuclear reactor and released radioactive wastes that were detectable over much of Europe and North America.
Soviet authorities have said that the accident was caused by operator errors and design defects in the plant, which is one of 15 such facilities in the U.S.S.R.
Officials for two international nuclear organizations projected in Vienna last month that 24,000 Soviet citizens eventually could die from cancer as a result of exposure to fallout from Chernobyl. Two days later, after Soviet and Western scientists reviewed radiation levels and the potential long-term risk, that estimate was revised to 5,000 deaths over the next 70 years.
Even the higher figure, reached by officials for the International Atomic Energy Agency and the London-based International Commission on Radiological Protection, would constitute less than 0.3% of the 9.5 million cancer deaths expected from other causes among more than 75 million people in affected areas of the Soviet Union.
According to the IAEA, the World Health Organization has been compiling data on contamination levels tied to Chernobyl found beyond Soviet borders, but no authoritative estimates are yet available.
Gofman's projections were based on information compiled by the U.S. Environmental Protection Agency and a June report from the World Health Organization on contamination levels from 30 reporting countries.
In a news conference announcing his findings, Gofman contended that the discrepancy between his estimates and those released in Vienna in late August were the result of other scientists' failure to consider low-level exposure to radiation.
He said scientists based their estimates on risk factors for developing cancer after radiation exposure that he claims are 25 times too low.
Scientists traditionally have based such risk estimates on assumptions from studies of victims of the atomic explosions at Hiroshima and Nagasaki, Gofman said. But those estimates fail to include cases of lung and breast cancer that recently have appeared in numbers that are sharply higher than normal among Japanese who were exposed to the radiation as children 40 years ago, he said.
Nor do they take into account published studies that have shown high rates of cancer among children exposed as fetuses to very low doses of X-rays while in the womb, he said.
Moreover, Gofman said, residue of radioactive fallout will remain in soil for at least five years. He called for cooperative international efforts to study exposed areas.
Don C. Scroggins, a Washington lawyer and former university chemistry professor who served on the White House Council on Environmental Quality, said he thought "the real risk" of cancer lay somewhere between the lowest estimates and Gofman's highest.
Scroggins, who appeared at the news conference Tuesday, said scientists will never be able to say with certainty that cancer cases diagnosed in the distant future were caused by exposure to fallout from Chernobyl rather than background radiation or other factors.
Gofman conceded that "cancer in individuals . . . 10, 20 or 30 years from now are not going to have a little flag that pops up and says, 'I was caused by Chernobyl.' "
Still, he said, available evidence suggests that even low levels of exposure to radiation will result in a greater risk of cancer.
"I'm not saying that everyone will get cancer, but there is a risk" far higher than many researchers will acknowledge, Gofman said.