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.
According to the NRC -- the U.S. government's atomic energy watchdog -- nuclear plants must be designed to withstand "the most severe natural phenomena historically reported for the site and surrounding area. The NRC then adds a margin for error to account for the historical data's limited accuracy."
However, earthquake resistance specifications for two plants on California's coast are lower than some historic quakes in the state, and much less than the magnitude-9.0 temblor that struck Japan last week.
The Diablo Canyon station north of Santa Barbara is built to withstand a magnitude-7.5 quake, and a plant at San Onofre, north of San Diego, can tolerate a 7.0 magnitude shock.
Three earthquakes of magnitude 7.5 or more have been recorded near these facilities in the past 200 years, according to the Southern California Earthquake Data Center at Caltech.
Nevertheless, Marvin Fertel, president and CEO of the Nuclear Energy Institute declared on the television program Meet the Press on Sunday that these and all other U.S. plants are "designed to withstand the maximum credible earthquake."
He added, "We've done things post-9/11 to make sure ... if you lost all power you could get water to the core and continue to cool it."
What appears to have been the critical factor leading to the Japanese reactors' problems was the tsunami.
The onrush of seawater knocked out the onsite generators that provided the power to water pumps for cooling the immensely hot reactors. Engineers have since been struggling to bring in and install replacement generators to resupply the reactors with cooling water.
Although both Diablo Canyon and San Onofre are on the Pacific coast, where they might be vulnerable to tsunamis, they are sited on headlands about 120 and 80 feet above sea level, respectively.
The tsunami that washed ashore in Japan last week was estimated at 20 to 30 feet.
On the other hand, some East Coast nuclear plants are virtually at sea level, such as Indian Point on the Hudson River north of New York City and Seabrook Station in New Hampshire.
Although tsunamis are much rarer in the Atlantic Ocean because of the different geology relative to the Pacific Rim, they are not unheard of. Lisbon and other towns along the Portuguese coast suffered major damage from a tsunami that followed an estimated magnitude-9.0 quake in 1755.
Also, according to the Maine Geological Survey, a tsunami struck eastern Canada in 1929, killing 25 to 50 people, with wave heights approaching 90 feet at the heads of some long, narrow bays that acted as funnels.
The NRC requires that nuclear facilities develop plans for dealing with radiation leaks into the surrounding environment, but gives them considerable latitude in determining the appropriate response to a given scenario.
Robert Rathie, an attorney involved with the independent committee monitoring safety at the Diablo Canyon Nuclear Power Plant, noted that every plant faces different risks based on the local geography.
Flexibility in the emergency plans makes sense, Rathie told MedPage Today in an interview.
Emergency practice sessions, overseen by the federal Nuclear Regulatory Commission, occur at least twice a year at the Diablo Canyon plant, he noted.
But state and local emergency services take on more of the safety planning for the community, with oversight by FEMA.
Key information, such as evacuation routes, for communities near a nuclear power plant can typically be found in the phone book, Rathie noted.
But "most people don't look for it until something like the Japanese nuclear emergency gets their attention," he said.
Indeed, many states may not have been giving nuclear disaster preparedness enough attention, according to a study released online today in the journal Disaster Medicine and Public Health Preparedness.
The survey of state departments of health indicated that those with a nuclear power plant were better prepared for a major nuclear emergency, but most still weren't prepared enough.
The 2010 survey predated the Japanese triple threat of earthquake, tsunami, and nuclear power plant equipment malfunction.
It reviewed written radiation response plans for the majority of states, most of which detailed communications issues during an emergency.
But the medical side of planning fell short.
Fewer than half of the states surveyed had written plans for radiation exposure assessment, environmental sampling, human specimen collection and analysis, and human health assessment.
These are all critical aspects of protecting people from the harmful effects of a radiation disaster, study author Sharon M. Watkins, PhD, of the Florida Department of Health, explained to MedPage Today.
State budget crunches have probably contributed to the problem, since many states said they just didn't have enough resources for those capabilities, she noted.
Ahead of an actual emergency, there's little physicians and other individuals can do to prepare, Watkins noted.
Rather, the group recommended action at the federal and state level.
Federal "best practices" for collaborations to get better-prepared states to share their knowledge with less-prepared states would be a good idea, Watkins suggested, noting that every state carries some risk of a nuclear disaster whether a transport accident, nuclear medicine problems, or a "dirty bomb" attack.
But medical staff at hospitals near the Diablo Canyon and San Onofre plants in California told MedPage Today that they believe they are prepared for the most likely radiation-related scenarios in their communities.
Medical centers in the vicinity of nuclear plants typically have a close working relationship with the emergency preparedness teams at those facilities, hospital managers said.
Staff from California's San Onofre nuclear facility do annual physician training and supply assessment at nearby Saddleback Memorial Medical Center in San Clemente, according to James Lenthall, director of safety services at the hospital.
Given the hospital's location within a 10-mile radius of the San Onofre plant, the NRC also requires that it conduct larger drills every three years in which the hospital practices receiving multiple victims of radiation exposure, Lenthall said.
In general, however, most training focuses on exposed plant workers, rather than a large-scale public health disaster, according to Julia Fogelson, MD, director of the emergency department of French Hospital Medical Center in San Luis Obispo, near the Diablo Canyon power plant.
Those workers would typically be decontaminated at the plant, although Fogelson said the hospital is prepared to prevent a radiated worker from posing a danger to other patients.
Like Lenthall, Fogelson emphasized that familiarity with the emergency managers at the nuclear facility is vital.
"We are all familiar with each other, and there's a comfort level and trust," she said. "There's a pretty well-oiled unit in place if anything were to happen."