An expert panel of the Cabinet Office on Dec. 15 endorsed the "most stringent" safety standard for radiation levels in evacuation zones and called for placing priority on decontaminating children's living environments.
An expert panel of the Cabinet Office on Dec. 15 endorsed the "most stringent" safety standard for radiation levels in evacuation zones and called for placing priority on decontaminating children's living environments.
But its report, the first government assessment of the health effects of low-dose radiation limits in evacuation zones around the Fukushima No. 1 nuclear power plant, drew immediate skepticism and criticism.
Some said the annual dose limit of 20 millisieverts to designate evacuation zones fails to take into account other health dangers from radiation. Others said the report does not adequately address the risks to children and expectant mothers.
And Kazuya Nakayachi, a professor of psychology at Doshisha University, indicated that many people simply will not believe the government since it lost public trust with its response to the nuclear disaster.
"Trust matters the most. People just don't believe when someone, in whom they don't trust, talks about risk," he said.
On the basis of the report, the administration of Prime Minister Yoshihiko Noda will prepare to shrink the nuclear evacuation zones. It plans to redesignate areas with annual doses of less than 20 millisieverts as "lifting preparation zones" so that evacuees can return home by the end of next year.
"This means that people will be able to live under 20 millisieverts," Goshi Hosono, state minister in charge of handling the Fukushima nuclear accident, told reporters after the panel meeting closed.
The panel was headed by Shigenobu Nagataki, a professor emeritus of radiology at Nagasaki University, and Kazuhiko Maekawa, a professor emeritus of emergency medicine at the University of Tokyo.
The report said "the most stringent figure was adopted from the viewpoint of safety," based on recommendations of the International Committee on Radiological Protection for annual dose limits in the range of 20-100 millisieverts in emergency exposure situations due to nuclear accidents.
The panel also noted that an annual dose limit of 100 millisieverts was used for the one-year period following the 1986 accident at the Chernobyl nuclear power plant.
"The response (in Fukushima) has so far been more rigorous than in the aftermath of Chernobyl," the panel's report said.
The report also asserted that an annual dose of 20 millisieverts "involves a lower health risk than other carcinogenic factors."
Although it said that a "simple comparison is not necessarily appropriate," the report contained reference examples: "Smoking is equivalent in risk to 1,000-2,000 millisieverts (per year), obesity to 200-500 millisieverts, and insufficient vegetable intake and secondhand smoke to 100-200 millisieverts each."
The panel recommended setting incremental decontamination targets, like "10 millisieverts per year in two years and 5 millisieverts per year on the next stage" to reduce the risk of exposure.
But Shinzo Kimura, an associate professor of radiology at Dokkyo Medical University, said the standard for evacuation orders should be tightened to 5 millisieverts per year.
Tatsuhiko Kodama, a professor of systems biology and medicine at the University of Tokyo, said the latest research in genome sciences shows that even low-dose exposure can cause chromosome aberrations and lead to bladder cancer and other diseases.
The panel's report was drawn up just over a month after it was set up. The experts met on eight occasions, first on Nov. 9 and the last meeting coming on Dec. 15.
The conclusion was reached one day before Noda announced that the Fukushima nuclear plant had reached a stable state of cold shutdown. In fact, the Noda administration set up the panel after learning that cold shutdown was expected by the end of this year.
In addition, the government felt the need to explain to the evacuees that low-dose exposure would have a limited impact on health.
The report recommended "priority measures for radiological protection" for children, who are said to be more susceptible to the effects of radiation. It said schools in the evacuation zones should be reopened only if the annual dose has fallen to 1 millisievert or less.
But that plan has not allayed the concerns of parents of young children.
"Radiation levels may rise again after one-time decontamination," said a 41-year-old woman from Minami-Soma, Fukushima Prefecture, who has evacuated to Saitama Prefecture with her two children. "Just decontaminating children's living environments would make no sense if radiation levels remained high in the surroundings."
Hiroyuki Yoshino, a 45-year-old resident of Fukushima city and a member of the Fukushima Network for Saving Children from Radiation, serves as an adviser to families with children who are considering evacuation.
Yoshino said of the government, "If they wish to regain trust, they should include us residents in the discussions."
Seiichi Nakate, a 50-year-old representative of the Fukushima Network, also criticized the panel's report as insufficient.
"The report says children are more susceptible, but it gives no concrete standards for children. I would have wished to see a comprehensive set of standards," Nakate said.
The panel apparently expected such criticism, and included in its report: "Efforts are necessary to minimize exposure doses to the least achievable levels."
(This article was written by Shinichi Sekine and Satomi Sugihara.)