Fukushima residents exposed to high doses of radiation

A Fukushima prefectural government survey on residents' external radiation exposure showed those in government-set evacuation zones were likely exposed to annualized radiation doses of up to 14 millisieverts, government sources said Friday.

This is the first statistical data indicating external radiation exposure among people living around the crippled Fukushima No. 1 nuclear power plant.

The prefectural government sent questionnaires to about 29,000 residents from Iitatemura, Namiemachi and the Yamakiya area in Kawamatamachi, which are designated as in either a no-entry zone or expanded evacuation zone, between late June and mid-July, ahead of those in other areas. The survey covered the four months after the crisis began.

The figure is based on analysis of questionnaires from 1,730 people who responded early. The prefectural Fukushima Medical University and the National Institute of Radiological Sciences analyzed the results of the survey.

About half of the surveyed residents from the three municipalities are believed to have been exposed to external radiation of at least the government-set annual limit of 1 millisievert, according to the sources.

While the prefecture projected the annualized external radiation exposure would be up to 5 millisieverts for most residents, the figure was 10 millisieverts or higher for about 10 residents.

Among those examined, a Fukushima plant worker was estimated to have been exposed to a maximum annualized dose of 37 millisieverts, while the highest dose among non-plant workers was 14 millisieverts. The resident is suspected to have gone through a highly contaminated area at the time of evacuation, according to the sources.

The prefectural government has been conducting health surveys on those who lived in the prefecture when the crisis broke out at the plant.

The prefectural government plans to release the survey results by the end of December.

Meanwhile, the city government of Koriyama, also in the prefecture, announced Thursday four primary and middle school students' cumulative radiation exposure exceeded 0.40 millisievert in the month from Oct. 5. The dose translates into an annualized dose of 4 millisieverts or more, city officials said.

The data was obtained from measurements by dosimeters that gauge cumulative radiation exposure. The city government distributed the dosimeters to 25,551 primary and middle school students. The cumulative radiation exposure levels among the students ranged between 0.01 millisieverts and 0.45 millisieverts, the city said.

"Experts told us the figures [for the four students] do not represent health problems, but we'd like to question the students to find out why their radiation exposure levels were high," a city official said.

The International Commission on Radiological Protection sets the annual limit for radiation exposure at 20 to 100 millisieverts at the time of an emergency and 1 to 20 millisieverts after the disaster has been contained.