Experts differ on Japan radiation threat

Even as the hundreds of thousands of people closest to Japan's wrecked nuclear power plant have been evacuated, radiation experts believe the public health threat can be contained.

"The risk to the United States, even in Hawaii, is very low, even in the worst-case scenario," said Norman Kleiman, director of the Eye Radiation and Environmental Research Laboratory at Columbia University's School of Public Health.

In Japan, the peril doesn't seem to approach what the former Soviet Union faced after the 1986 Chernobyl reactor disaster, the worst such accident ever, two experts said.

Kenneth Kerns, associate director of environmental health and safety at Iowa State University, called the earthquake-damaged Fukushima Dai-ichi plant "a very serious situation."

But, he said, the Japanese responded quicker than authorities at Chernobyl.

He compared the threat to 50 or so workers inside the plant to that of firefighters putting out a blaze.

People living within 12.4 miles of the plant were ordered evacuated and those within 18 miles were told to stay indoors. Iodine tablets, used to protect the thyroid gland from radioactivity, have been distributed.

Still, even in a worst-case scenario in which the reactor core is exposed, "it would release material in the air that would be a fraction of that released at Chernobyl," Kerns said.

The Chernobyl blast occurred as the plant was being tested at maximum power. It spewed massive amounts of radioactive particles high in the atmosphere over Ukraine, Belarus and parts of Russia. Thirty plant workers died within weeks of radiation sickness.

By contrast, the Japanese plant is already shut down.

"That was a runaway train," Kerns said of Chernobyl. "Here, they've basically done everything to prevent fissioning" of nuclear material.

But Robert Alvarez, a senior scholar at the Institute for Policy Studies in Washington, D.C., and a nuclear energy adviser during the Clinton administration, was less confident that Japan's health consequences would be minimal.

"We've never had multiple runaway reactors before," he said, referring to the three reactors the workers are trying to prevent from melting down. "We're operating on fragments of information."

Alvarez said "some untold number" of nuclear plant workers could die in the near term and others might develop cancers over time.

Kleiman said two decades of research have found that health effects from the Ukrainian accident have not proved as dire as once feared.

About 500,000 workers from the plant and the cleanup effort, along with another 3 million to 5 million people, were exposed to increased radiation, he said.

A recent United Nations report said about 6,000 cases of thyroid cancer -- treatable if detected early -- were found in children. "Apart from this increase, there is no evidence of a major public health impact," it said.