89 Millisieverts Equivalent Dose at Thyroid from a Resident in Namie-machi, Fukushima, Says Hirosaki University Researchers

Professor Shinji Tokonami, Department of Radiation Physics, Institute of Radiation Emergency Medicine, Hirosaki University and his researchers say people who escaped from the coastal areas of Fukushima Prefecture after the accident and people who continued to live in Namie-machi after the March 11, 2011 nuclear accident were found with high levels of radiation exposure on the thyroid.

They tested 65 residents in April 2011, and it is in the news on March 9, 2012. Another case of nearly one-year delay in disclosing the information that would have made the difference if known earlier. Like 11 months ago.

From Asahi Shinbun (3/9/2012):

東京電力福島第一原発事故で、放射性ヨウ素によって甲状腺に９０ミリシーベルト近い被曝（ひばく）をしていた人がいることが分かった。弘前大学被ばく医療総合研究所の床次眞司（とこなみ・しんじ）教授らが、事故の約１カ月後に行った住民６５人の測定結果を分析した。被曝した人の約半数が１０ミリシーベルト以下だったが、５人が５０ミリシーベルトを超えていた。

It has been disclosed that someone was exposed to nearly 90 millisievert radiation [equivalent dose] on the thyroid from radioactive iodine during the Fukushima I Nuclear Power Plant accident. Professor Shinji Tokonami, Department of Radiation Physics, Institute of Radiation Emergency Medicine, Hirosaki University and his researchers analyzed the test result of 65 Fukushima residents. The test was conducted 1 month after the accident. Of people who were exposed to radiation, about half had equivalent dose of 10 millisieverts or less, but 5 people had equivalent dose exceeding 50 millisieverts.

　甲状腺被曝はがんのリスクがあるが、ヨウ素は半減期が短く、事故直後の混乱などで、きちんとした計測はされておらず、詳しい実態は分かっていなかった。

The radiation exposure on the thyroid increases the risk of cancer. However, radioactive iodine has a short half life, and the exposure was not measured properly in the confusion right after the accident and the details were not known.

　床次さんらは昨年４月１１～１６日、原発のある福島県浜通り地区から福島市に避難してきた４８人と、原発から３０キロ圏周辺の浪江町津島地区に残っていた住民１７人を対象に、甲状腺内の放射性ヨウ素の濃度を調べた。この結果、８割近い５０人からヨウ素が検出された。

From April 11 to 16 last year, Professor Tokonami's group measured the density of radioactive iodine in the thyroid of 48 people who evacuated from Hamadori (coastal 1/3 of Fukushima) to Fukushima City and 17 people who remained in Tsushima District of Namie-machi, right outside the 30 kilometer radius from the nuclear power plant. Radioactive iodine was found in 50 people, nearly 80% of people tested.

　この実測値から、甲状腺の内部被曝線量を計算した。事故直後の３月１２日にヨウ素を吸い込み、被曝したという条件で計算すると、３４人は２０ミリシーベルト以下で、５人が、健康影響の予防策をとる国際的な目安の５０ミリシーベルトを超えていた。

From the actual measurement, the researchers calculated the equivalent dose at the thyroid. Assuming they had inhaled radioactive iodine immediately after the accident on March 12 and were exposed to radiation, the calculation showed that 34 people had equivalent dose of 20 millisieverts and less, and 5 people exceeded 50 millisieverts, which is an international standard for intervention to prevent negative effect on health.

　最高は８７ミリシーベルトで、事故後、浪江町に残っていた成人だった。２番目に高かったのは７７ミリシーベルトの成人で、福島市への避難前に同町津島地区に２週間以上滞在していた。子どもの最高は４７ミリシーベルト。詳しい行動は不明だ。

The maximum equivalent dose was 87 millisieverts, from an adult who remained in Namie-machi after the accident. The second highest was 77 millisieverts from an adult who had spent more than 2 weeks in Tsushima District of Namie-machi on his/her way to evacuate to Fukushima City. The highest dose in children was 47 millisieverts. There is no information of whereabouts of the child during the weeks in March and April.

　国が昨年３月下旬、いわき市、川俣町、飯舘村の子ども１０８０人に行った測定では、３５ミリシーベルトが最高値と公表されていた。

In the test done by the national government late last March on 1,080 children in Iwaki City, Kawamata-machi, and Iitate-mura, 35 millisievert equivalent dose was announced as the maximum.

From Asahi's extremely convoluted tabulation, here's what I've figured out (I think, maybe):

• 48 people from Hamadori (coastal 1/3), 17 people who remained in Tsushima District of Namie-machi, total 65 people

• Radioactive iodine detected in 50 people

• 25 people below 10 millisieverts equivalent dose
  

• 9 people between 10 and 20

• 11 people between 20 and 50

• 5 people above 50

Why can't Asahi say it straight? (Rhetorical question in case you're wondering.)

NHK, reporting on the same news, says the researchers are yet to tell the residents about the test result:

調査チームでは、今後、検査を行った住民に対し結果を報告することにしています。

The researchers plans to tell the residents about the test result in the near future.

How nice of them.

Hirosaki University is one of the 86 national universities in Japan.

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