JAPAN | City in Chiba Prefecture sets independent radiation dose standard for children

Posted on June 23, 2011


JAPAN | MAINICHI | 23 June 2011

NODA, Chiba — The municipal government here independently set a 1.0 millisievert maximum annual radiation dose for children, and will take anti-exposure measures should doses at schools in the city exceed that figure, it was announced on June 22.

Noda and other municipalities in northwest Chiba Prefecture, where radiation levels are higher than surrounding areas, decided not to base local policy on the central government’s safe figure of an annual 20 millisievert dose, drawing fire from some parents. Noda elected instead to issue its own, much more severe standard, and the contrast between the local and central government maximum doses is likely to influence other local bodies as they wrestle with the radiation problem.

According to Noda city officials, they set the new limit based on that recommended by the International Commission on Radiological Protection (ICRP). The new maximum dose breaks down to an hourly dose of 0.19 microsieverts, presupposing that a child spends eight hours a day outside. The municipal government will now begin measuring radiation levels at nursery schools, kindergartens, daycares for students, children’s centers, and primary and junior high schools across the city.

Meanwhile, the city is taking more detailed readings at a nursery school playground where radiation has already exceeded the new standard. Parts of the playground, where radiation of 0.25 microsieverts per hour has been detected, have been declared off-limits, while staff and children at the school must wear hats and wash their hands and gargle regularly. Staff also wear dosimeters to allow tracking of their cumulative dose. The city will apply the same rules to any facility that exceeds the new maximum, and forbid access to any areas with a radiation level of 0.3 microsieverts per hour or more.

The Ministry of Education, Culture, Sports, Science and Technology had announced in April restrictions on outdoor activities for children if radiation exposure reaches 3.8 microsieverts per hour, in line with its policy of an annual 20 millisievert maximum dose. The ministry’s new recommendations released the following month, however, states that exposure be kept to 1 millisievert per year. The move has caused confusion among parents.

“The standard for children should be set at the low-end of the scale, at 1 millisievert,” Noda Mayor Takashi Nemoto said of the city’s new radiation exposure standard for children. “In order to break out of this situation, with the whole area being referred to as a ‘hotspot,’ clear standards must be set.”

Surrounding municipalities, meanwhile, have been confused by Noda’s move. Noda and five other municipalities in northeast Chiba Prefecture formed an anti-radiation measures committee on June 8, and were creating united radiation measurement and evaluation standards.

According to measurements taken by the six municipalities and the prefecture, four including the city of Kashiwa had radiation levels exceeding the Noda standard at every test location.

“I suppose Noda has its own conditions,” Kashiwa Mayor Hiroyasu Akiyama told the Mainichi.

A petition calling for Kashiwa to replace all the topsoil at kindergartens and schools in the city was signed by more than 10,000 people.

“I’m envious of the people in Noda,” said 33-year-old Yuki Osaku, who presented the petition to the Kashiwa municipal government. “I want the government to take quick action.”

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