Health Risks to U.S. From Japanese Nuclear Crisis Seen as Low

March 15, 2011— -- The world watches anxiously as Japanese authorities try to prevent meltdowns at two nuclear power stations rocked by last week's earthquake and tsunami; many in the U.S. are asking whether they may be in danger.

MedPage Today took a look at the risks that radiation leaks from the Japanese plants may pose to the U.S., whether plants here may be vulnerable to natural disasters, and what our level of medical preparedness is.

The general consensus among our sources: The risk is low.

Read this story on www.medpagetoday.com.

Will Radiation from Japan Threaten the U.S.?

Experts contacted by MedPage Today generally agreed that radioactive particles will eventually reach the U.S., but at levels too low to measurably affect people's health.

In an update today, the International Atomic Energy Agency said winds have been blowing eastward from the Japanese coast -- toward the U.S. and Canada -- in a pattern expected to continue for the next three days.

But the U.S. Nuclear Regulatory Commission (NRC) said it is unlikely that harmful levels of radiation leaking from Japanese reactors will reach any part of the U.S., including Hawaii, Alaska, and various territories in the Pacific, considering the vast distances between Japan and those areas.

Reports indicate that any release of radioactive materials has been largely confined, and that explosions at the Fukushima Daiichi nuclear power plant have not breached their outwardmost containment buildings.

Dr. James Thrall, radiologist-in-chief at Massachusetts General Hospital in Boston and president of the American College of Radiology, told MedPage Today that the chances of a consequential radiation exposure from the Japanese disaster anywhere in the U.S. is "essentially zero."

He noted, however, that radiation detectors are so sensitive that they will likely be able to measure even minute levels of radioactivity from Japan on U.S. soil.

That's how the world knew about the 1986 Chernobyl disaster, which occurred in what is now Ukraine, before Soviet government officials admitted it had occurred, according to Eric Hall, director of the Center for Radiological Research at Columbia University in New York City.

At Chernobyl, the fuel rods melted through all layers of containment, accompanied by several explosions.

Hall said in an interview that an event like that is unlikely to repeat itself in Japan, as the reactors are more modern with better containment systems than those at Chernobyl. The reactor at Chernobyl was also of a different design -- one that left it more prone to violent explosions.

But, even in the hypothetical scenario of a Chernobyl-like event in Japan, it is highly unlikely there would be any health-related consequences in the U.S., both Thrall and Hall said.

Thrall pointed out that the U.S. tested nuclear and hydrogen bombs in the Pacific Ocean for years, and dropped atomic bombs in Japan during World War II, "which released, in the aggregate, far more radiation than these [Japanese] power plants would ever come close to releasing, and it all dissipated in the atmosphere, at least from the standpoint of any health implications in the U.S."

According to Thrall, the average background radiation exposure in the U.S. at sea level is 3.2 mSv.

Both Thrall and Hall said that any radiation release that would bring that up to about 6 mSv would be cause for alarm and would trigger actions to mitigate the health effects, including the use of potassium iodide tablets to address iodine-131 exposure and ferric hexacyanoferrate(II) (Radiogardase) capsules to mitigate cesium-137 exposure.

But both called that scenario highly unlikely.

Kirby Kemper, a physicist at Florida State University, told MedPage Today and ABC News in an e-mail that the health risk attributable to low levels of radiation remains controversial.

But, he noted by way of comparison, "people in Denver ... have about twice the background radiation level compared to people in Florida due to cosmic rays, but actually have a longer life span than people from Florida."

Dr. Jerrold Bushberg, a radiation oncologist at the University of California Davis, said that even if there is a risk from radiation drifting over from Japan, it will be trivial relative to the overall risk of cancer.

In an e-mail to MedPage Today and ABC News, Bushberg said that an extra dose of radiation of 40 times the normal background radiation from cosmic rays and geologic sources still would be barely detectable.

"The increased cancer risk from that exposure would be less than 1 percent," he said.