Radioactivity? Be concerned for the Japanese; risk to U.S. is virtually nil

Northwesterners worried about health fallout from Japan's crippled nuclear reactors can take comfort in the 4,500 miles of ocean that separate us.

While people living near the Fukushima Daiichi nuclear complex could face serious risk if the situation were to worsen, experts say even a complete meltdown is unlikely to create a danger in the United States. Radioactive plumes could be generated, but they would dissipate as they cross the vast expanse of the Pacific.

"I'm very concerned that there could be a fairly significant problem in Japan," said Dr. Ira Helfand, board member of Physicians for Social Responsibility. "I'm less concerned about the health effects here in the United States."

No radiation from the disabled reactors has been detected anywhere in the United States. But the specter that spent nuclear fuel stored in reactor-top pools could ignite and loft radioactive material into the air ratcheted up anxiety Tuesday, and shifted the crisis into uncharted waters, Helfand said.

"It's very hard to know," he said, "but I think the danger to the West Coast is still going to be quite small because of the huge distance involved."

University of Washington atmospheric scientist Dan Jaffe calculates it would take seven to 10 days for radioactive material injected high into the atmosphere — as in a spent fuel fire — to waft from Japan to Washington or Hawaii. Radioactive material at lower levels — as would be expected from a meltdown — would take about two weeks to cross the Pacific. Travel times to Alaska would be several days shorter.

"Time is your friend because you get more dilution, more removal and more radioactive decay of the particles before they arrive," Jaffe said. And the United States would have time to prepare if the crisis spirals into an unforeseen catastrophe that could cause dangerous exposures here.

By the time a radioactive plume reached the Washington coast, Jaffe estimates it would be diluted by a factor of at least 10,000 and possibly 1 million.

"I would say there's no risk for us in Washington, and I would not be concerned if I was in Alaska or Hawaii," he said.

The then-Soviet Union's 1986 Chernobyl explosion — the worst nuclear disaster in history — ejected amounts of radioactive material that dwarf releases from the Japanese reactors. Areas up to 600 miles from the plant in the Ukraine were showered with dangerous levels of radionuclides blamed for higher levels of thyroid and other cancers years later. Trace amount of radioactive material circled the globe.

But in the United States and other countries farther away, there was not even a need to take precautions because the risks were so low, said Donn Moyer, spokesman for the state Department of Health.

Japan's close neighbors, including Russia, are tracking the crises closely — but have detected no elevated radiation.

Along with other West Coast health authorities, the state Department of Health is monitoring radiation levels, Moyer said. Trace levels may reach the coast if one or more of the reactor cores melts or if spent fuel ignites. But modern sensors can detect concentrations far below levels that would cause health effects, said Kathryn Higley, director of Oregon State University's Department of Nuclear Engineering and Radiation Health Physics.

Still, many West Coast residents are jittery and mistrustful of officials urging calm.

"I just don't think that we can expect an honest report," wrote one participant in a Seattle Times online Q&A with Higley on Tuesday.

Some people have been rushing to buy potassium iodide tables, which can protect against radiation-induced thyroid cancer. The tablets flood the thyroid with normal iodine, which prevents absorption of the radioactive form of iodine that is one of the more harmful components of nuclear fallout.

But the pills can have side effects, including nausea and diarrhea, and can aggravate kidney disease and other underlying health problems, according to the Mayo Clinic.

Japanese officials are prepared to distribute pills to people living close to the damaged reactors. They also were distributed widely in post-Chernobyl Europe.

Health officials say nobody in the United States needs to take the pills. No radioactive iodine, or radioactive materials of any type, have reached the United States from Japan, Moyer said. The pills also offer no protection against other types of cancer or radioactive particles. Even residents of Tokyo, about 100 miles from the reactors, have not been given potassium iodide.

"There's a huge misunderstanding about what it does," Moyer said. "Some people call it an anti-radiation pill, but it's not."

Higley's suggestion: Don't spend money on potassium iodide. Send it to the Red Cross.

Sandi Doughton: 206-464-2491 or sdoughton@seattletimes.com

Information from The Associated Press is included.