The nature of the threat has changed over time. Initially, it was exposure to the large releases of radiation from explosions at the plant. The risk from leaks remains but at a much reduced level.
These days, the main danger is less obvious but just as real: consuming contaminated food and water and ingesting radioactive particles. Radioactive material has accumulated in gutters where rainwater collects and shrubs with leaves that suck in radiation.
The risk is cumulative. The radioactivity in one's body builds up through various activities, including eating contaminated food every day or staying in a hot spot for an extended period.
Schools are restricting outdoor activities, and radiation meters dot the streets. Some people are using their own devices to measure radioactivity.
At area hospitals, thousands of people are on waiting lists to get their radiation levels measured with whole-body counters. One child at Minami Soma Hospital, southeast of Fukushima, was found with 2,653 becquerels of radioactive cesium.
It's a big number, but is it dangerous? Jacques Lochard, an International Commission on Radiological Protection official advising Fukushima prefecture, says the child's exposure could amount to as little as 0.3 millisieverts a year, or as much as 8 millisieverts, depending on how the child was exposed to the radiation.
All most residents know is that their bodies are contaminated. What the numbers mean is unanswered.
Kunihiko Takeda, a nuclear and ecology expert who has been more outspoken about the dangers than many others, says people become less afraid after he explains the risks.
"They are freed from the state of not knowing," says Takeda, who has a blog with instructions on how parents can protect their children from radiation. "They now know what to do and can make decisions on their own."
Lochard says he was sad to hear about a Fukushima woman whose children were too afraid to bring her grandchildren from Tokyo for visits. All the parents need to do, he said, is bring food from home and keep the children indoors.
Still, Lochard says, "There is no safe level. It is a small risk but not zero."
After the 1986 Chernobyl accident, more than 6,000 thyroid cancers clearly linked to radioactive iodine were found in children and adolescents. A study by Weiss' U.N. committee found exposure to iodine was lower in Fukushima than at Chernobyl. Still, parents are worried because the Chernobyl cancers didn't emerge until a couple of years later.
"Nobody can say this is over. I'd be the last to say that," Weiss says.
Mayor Shouji Nishida of Date, a city of 66,000 people in Fukushima prefecture, says his community is preparing for the future by relying less on the central government, and by adjusting expectations. He believes 5 millisieverts of radiation a year — five times the typical amount of background radiation in Japan — is a realistic goal.
"We are defining policies to live and coexist with radiation," he says.
Kunihiko Takeda's blog (in Japanese): http://takedanet.com/
Follow Yuri Kageyama on Twitter at http://twitter.com/yurikageyama
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