Preliminary Reports Show Little Radiation Exposure in Fukushima

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It’s now eight months since a devastating earthquake and tsunami hit northern Japan, badly damaging the Fukushima Daiichi nuclear complex. That accident eventually resulted in a meltdown, and the accident as a whole was rated a 7 on the International Nuclear Event Scale’s 1 to 7 rating. Explosions in the plant threw large amounts of radiation—about one-tenth the amount released after the Chernobyl disaster—into the air, prompting the Japanese government to create a 20 km (12 mile) evacuation zone around the plant. More than half a year later, some 100,000 residents have yet to return home.

How long they’ll have to stay away—and how great the lasting public health impacts of Fukushima will be—will depend on how much radiation has actually found its way into the bodies of residents. That’s a long-term question, but a preliminary report (PDF) published in the November 16 PLoS ONE indicates that the situation may not be as severe as first feared.

In the immediate aftermath of the tsunami on March 11—and the accident at Fukushima—the Japanese government asked institutions to monitor radioactive contamination levels among affected residents. That included Hirosaki University, more than 350 km north of Fukushima City. Support staff from Hirosaki surveyed more than 5,000 residents in the months following the accident, and kept track of their own exposure levels as well.

The PLoS study, led by Ikuo Kashiwakura, found only 10 people among those surveyed with high levels of radiation exposure—and even those levels were not elevated enough to require decontamination. (The study covered March 15 to June 20.) Almost everyone else surveyed had low to nonexistent levels of radiation contamination, while the Hirosaki staff members on site had undetectable radiation levels.

Not everything was safe. The study found hotspots where radiation had accumulated, and the researchers also noted that outdoor air tended to be nearly 10 times more contaminated than air indoors. But as a preliminary study, the PLoS paper should allow Fukushima residents some relief. The region is still years away from being whole again, and scientists will need to keep long-term tabs on residents in case any radiation-related health problems do arise. But it could have been much worse.