information about Fukushima published in English in Japanese media info publiée en anglais dans la presse japonaise
21 Février 2012
February 21, 2012
http://mdn.mainichi.jp/mdnnews/news/20120221p2a00m0na018000c.html
The government's Nuclear Emergency Response Headquarters did not fulfill requests from the Cabinet's Nuclear Safety Commission of Japan (NSC) to conduct further testing on the internal radioactive exposure of children whose levels were within the maximum allowable amount, but nonetheless high, it has emerged.
Between March 26 and March 30 last year, the emergency headquarters used simple radiation sensors to test thyroid radiation exposure among 1,080 children between the ages of 0 and 15. The children were living in areas outside the 30-kilometer radius from the Fukushima No. 1 Nuclear Power Plant where high levels of radiation exposure were likely.
None of the children registered radiation exposure levels exceeding 0.2 microsieverts per hour, the figure set by the NSC as one above which children would be required to undergo a more thorough examination. However, one child from the Fukushima Prefecture city of Iwaki registered 0.1 microsieverts per hour, whose accumulated thyroid exposure to radiation was calculated to be around or above 30 millisieverts.
On March 30, after the NSC was informed of the results from the government's nuclear emergency headquarters, NSC asked that additional tests be conducted on the child with a thyroid monitor, which is capable of taking more precise measurements.
"Because iodine has a short half life, it's hard to get a grasp of what's going on unless measurements are taken early on," an NSC official explains.
On April 1, 2011, however, the government's emergency headquarters decided not to conduct further tests, citing "the difficulty of transporting a 1-ton thyroid monitor," "requiring the child to travel long distances for tests," and "risk of spreading extreme panic and making the child, the child's family and their local community targets of unwarranted discrimination" as reasons.
Yasumasa Fukushima, head of the nuclear emergency headquarters' medical support division, says: "I don't know what specifically transpired at the time, but ultimately the parties involved agreed not to conduct further testing. Thinking back on it now, we should have."
"Perhaps we should have used stronger language in appealing for further tests," says an NSC official. "We weren't satisfied with the emergency headquarters' response, but we feared that we would be stepping on toes and didn't push the matter any further."
Last June, the International Atomic Energy Agency (IAEA) changed its guidelines for ingesting potassium iodide to prevent thyroid exposure to radioactive iodine. Based on information that accumulated thyroid exposure to radiation of 50 millisieverts can elevate the risk of thyroid cancer in children, the standard was lowered from 100 millisieverts to 50 millisieverts. The 30 millisieverts detected in the child from Iwaki was not far from that limit, and depending on how the crisis unfolded, the situation could have gotten worse.
Meanwhile, Yoshihisa Matsumoto, an associate professor of radiobiology at Tokyo Institute of Technology says: "Based on data we have obtained, I don't think we'll see an increase in thyroid cancer in Fukushima. But if more precise data had been collected at the time, it could have been used to put residents' minds more at ease."
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