LINDA WERTHEIMER, host:
The United States yesterday authorized the evacuation of American diplomats and their families as concerns about the nuclear crisis deepened in Japan. Starting today, charter planes are being sent for all American citizens in Japan who want to leave. The U.S. government also said Americans should defer all nonessential travel to Japan because of the risk of radioactive contamination.
People as far as California are worried about exposure to radiation. But experts say that anxiety is misplaced. Right now the only people in danger are the ones who actually work at the nuclear plant. NPR's Jon Hamilton has the story.
JON HAMILTON: It's hard to find potassium iodide pills on the West Coast of the U.S. these days. People have bought them all up to protect themselves from radiation.
Jonathan Links of Johns Hopkins University says the pills offer pretty limited protection. More to the point, he says, the Dai-ichi nuclear plant hasn't released enough radiation to cause health problems in most of Japan, let alone in the U.S.
Links directs the Center for Public Health Preparedness at Hopkins' Bloomberg School of Public Health. He says the people he's worried about are the workers still trying to gain control of the overheating nuclear reactors at Dai-ichi.
Dr. JONATHAN LINKS (Director, Center for Public Health Preparedness, Bloomberg School of Public Health, Johns Hopkins University): I think it likely that they've gotten doses worth paying attention to.
HAMILTON: At one point, a reading at the plant indicated there was enough radiation to cause acute radiation sickness for anyone exposed for more than a couple of hours. But Links says that was a peak level. Subsequent readings have shown much less radiation.
Dr. LINKS: The critical piece of information that's missing is how long they were exposed to that rate.
HAMILTON: Links says he would have been concerned about exposure among people who live near the plant. But the government quickly evacuated everyone within 12 miles.
Dr. LINKS: And so the group that would otherwise be at risk, those local residents were evacuated very early on. And I think at this point it's very unlikely they received any noticeable dose at all.
HAMILTON: As for people in the rest of Japan, Links says something extraordinary would have to happen at the Dai-ichi plant before they would face any risk. And even then, he says, the situation in Fukushima would not resemble Chernobyl in 1986; there, a nuclear reactor exploded and released enough radiation to sicken or kill dozens of people within hours.
Dr. LINKS: Were there to be releases, the concern would not be about acute effects. It would be about the main delayed effect, which is cancer.
HAMILTON: In Chernobyl, the biggest problem was thyroid cancer in people who were exposed to radioactive iodine as children.
Links says the situation in Fukushima is more like what happened in Three Mile Island, Pennsylvania. That was where, in 1979, a nuclear reactor overheated and released radioactive steam.
Evelyn Talbott is an epidemiologist at the University of Pittsburgh, who studied what happened to 32,000 people who lived near the reactor.
Dr. EVELYN TALBOTT (Epidemiologist, University of Pittsburgh): There was radiation leakage, you know, during the 10 days after the accident. The exposure was on average about 25 millirem, which is a couple of chest X-rays.
HAMILTON: Not much, although some scientists believe it may have been more. In any case, Talbott was part of a team which tracked the health of people in the area for decades.
Dr. TALBOTT: So the good news was, after 20 years, we really didn't see any overall cancer increase, comparing the 32,000 people at Three Mile Island with the individuals - the rest of the individuals in Pennsylvania.
HAMILTON: Experts say workers at the Fukushima plant may not be so lucky. But the Japanese public should be okay.
It's important to keep the problem of radiation in context. Luis Echavarri is the director-general of the Nuclear Energy Agency at the Organisation for Economic Cooperation and Development. He says the biggest problems in Japan are still the earthquake and the tsunami.
Dr. LUIS ECHAVARRI (Director-General, Nuclear Energy Agency at the Organisation for Economic Cooperation and Development): The number of people killed by these natural events is rising and rising. So far, the effects of the radiation on people have nothing to do with that.
HAMILTON: The Japanese government has confirmed that more than 4,000 people died in the earthquake and tsunami. Many thousands more remain missing.
Jon Hamilton, NPR News.