1 Millisievert Internal Radiation from a Man in Minami Soma City

Minami Soma City, while waiting for the lifting of the "evacuation-ready zone" designation, tested the internal radiation exposure of the residents in the high-radiation area within the city using the whole body counter.

Over 1 millisievert internal radiation was found in a man in his 60's, but the rest of the residents tested less than 1 millisievert, and the mayor of the city is pleased with the result.

From Asahi Shinbun (8/13/2011):

福島県南相馬市が住民の内部被曝（ひばく）を調べたところ、６０代の男性１人から１ミリシーベルトを超える数値が検出されたことが分かった。市立総合病院が１３日発表した。住民の検査で１ミリシーベルト以上の内部被曝が明らかになったのは初めて。

Minami Soma City in Fukushima Prefecture tested the internal radiation exposure of the city's residents, and found one man in his 60's with more than 1 millisievert radiation. The result was announced by the City General Hospital on August 13. It is the first time that internal radiation of more than 1 millisievert has been detected in the survey of the city residents.

　今回はホールボディーカウンターと呼ばれる機器を使い、体内に取り込まれた放射性セシウムなどによる将来にわたる被曝量を評価した。放射性物質の量が半分になる期間は、セシウム１３７では尿や便などに混じって排泄（はいせつ）される分も考えると０～１歳児で９日間、３１歳以上で８９日。放射性物質は現時点では相当減っていると見られている。

The whole body counter was used to evaluate the radiation exposure in the future from the ingested radionuclides such as radioactive cesium. Half life of cesium-137 in the body, taking into account the amount that will be expelled in urine and stools, is 9 days for children aged between 0 and 1, 89 days for people over 31. At this point, the amount of radioactive materials in the body is considered to have decreased significantly.

　調査は放射線量が高い地区で暮らしている１６歳以上の５６９人と、原発事故時に市内に在校していた６～１５歳の小中学生３３０人が対象。同病院によると、１．０２ミリシーベルトが測定された６０代男性は３月１２日、水を確保するために山中に滞在していたという。

The survey was done on 569 people over the age of 16 who live in a high-radiation area in the city and 330 students aged between 6 and 15, who attended the elementary schools and junior high schools in the city at the time of the accident. According to the hospital, the man who has been found with 1.02 millisievert internal radiation stayed in the mountain on March 12 to secure water supply.

Kahoku Shinpo (local Fukushima paper) reports that the mayor of the city is pleased with the result, and thinks it will reassure the residents that it is safe to live in Minami Soma City:

桜井勝延市長は「市民１人が１ミリシーベルトに達したのは残念だが、大半の受診者は安心できる数値。市内が、生活に支障ない環境と判断してもらえるのではないか」と述べた。

Mayor Katsunobu Sakurai said "It is regrettable that one resident exceeded 1 millisievert. But the vast majority of the residents tested at the safe level. I believe the residents of the city can judge from the result that the city is safe to live and work."

And what is the result that made the mayor happy? According to Kahoku Nippo,

検査結果によると、治療が必要とされる２０ミリシーベルト以上の被ばくが確認された人はいなかった。線量は成人受診者の９９％に当たる５６１人が０．５ミリシーベルト未満、７人が０．５ミリシーベルト以上～１ミリシーベルト未満。小中学生はセシウムが検出された２人以外は、検出限界以下だった。

There was no one exceeded 20 millisieverts, the level at which a treatment may become necessary. 561 adults, 99% of the subjects, tested less than 0.5 millisievert; 7 adults tested between 0.5 and 1 millisievert (not exceeding 1 millisievert); 2 school children was found with radioactive cesium, but the rest tested below the detection limit.

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