September 1, 2020. This article records radiation scientist Jun Takada’s 2011 measurements and proposals concerning external exposure, internal exposure and thyroid doses following the Fukushima Daiichi accident. It examines the Kan administration’s failure to use personal dosimeters and Japan’s radiation-protection capabilities, while proposing topsoil-decontamination centres to rebuild Fukushima’s agriculture and dairy farming.

The following is a continuation of the preceding chapter.
【There Will Be No Radiation-Related Health Damage in Fukushima】
Kunihiko Takeda takes issue with the government’s decision to raise the annual exposure limit for disaster-affected residents to 20 millisieverts.
He states, “Following the Chernobyl accident, childhood cancer began to appear in the fourth year after exposure.”※8
Although he does not specify it, he is referring to thyroid cancer.
It is a serious problem that this statement gives readers the misleading impression that such cancer occurred at radiation doses as low as those being discussed here.
In the affected areas around Chernobyl, thyroid doses reached a maximum of 50 sieverts, with many people receiving doses of several sieverts, and it was because of these exposures that such illnesses occurred.
In Belarus, the annual incidence among children reached four cases per 100,000 four years after the accident, peaked at thirteen cases nine years afterward, and subsequently began to decline.
In Fukushima, the thyroid doses received by prefectural residents were between one-thousandth and less than one-ten-thousandth of those recorded following the Chernobyl accident.
Among the 66 people I examined, the highest dose was 8 millisieverts.
Judging from the radiation doses, the risk of thyroid cancer among Fukushima residents would be no more than one case per ten million people per year.
However, because Fukushima Prefecture has a population of approximately two million, no one would develop thyroid cancer as a result of this low level of exposure.
Those who use amateur knowledge to frighten the people of Fukushima and the Japanese public must stop.
Regarding whole-body external exposure, the maximum dose among evacuees from within 30 kilometres of Chernobyl was as high as 750 millisieverts over seven days.※9
By contrast, judging from changes in outdoor ambient dose rates at the time, the doses received by emergency evacuees from within 20 kilometres of Fukushima were on the order of millisieverts—less than one-hundredth of the levels at Chernobyl.
It is therefore close to criminal to invoke the health damage caused by Chernobyl in order to frighten Fukushima residents and other Japanese citizens about their own possible health effects.
Radiation effects on women’s ovaries are known to occur at doses of 650 millisieverts or more.
It is therefore true that evacuees from within 30 kilometres of Chernobyl faced a severe situation.
However, I can state categorically that no comparable risk exists in Fukushima or in any other Japanese prefecture.
I believe that almost no Fukushima residents will receive an annual dose reaching 20 millisieverts.
On the basis of cumulative readings from personal dosimeters used during the author’s own investigations, the estimated 30-day doses in April–May and June–July were no more than 1.0 millisievert within and around the 20-kilometre zone, and no more than 0.10 millisievert from Aizu to Fukushima.
On this basis, I estimate that the annual external dose received by Fukushima residents in 2011 was no more than 10 millisieverts, and no more than 5 millisieverts for most residents.
A scientific assessment could have been obtained by equipping everyone, from children to adults, with personal dosimeters.
However, the government’s disaster-response headquarters failed to do this during the initial period from March through May, when radiation levels were comparatively high.
This was an appalling lack of proper administration.
It is particularly inexcusable because indoor-sheltering advisories had been issued at the time for Iitate Village and other areas.
On the basis of these measurements with personal dosimeters, I provisionally assess that the external exposure received by most Fukushima residents in 2011 amounted to several millisieverts.
【Building Decontamination Centres and Reconstructing Fukushima】
Regarding internal exposure, the author has conducted on-site examinations of thyroid doses from radioactive iodine and doses from caesium inside the body.
More than 100 people who requested examinations have so far been tested in Nihonmatsu, Fukushima, Minamisoma, Iwaki and Koriyama.
The thyroid doses of 68 Fukushima residents examined were below 8 millisieverts.
Caesium examinations conducted by August on 52 residents, including babies and young children, showed internal doses below 0.1 millisievert in nearly every case.
In particular, the internal caesium doses of all the children examined so far have been no more than 0.1 millisievert.
The author independently developed this method of on-site internal-exposure assessment through joint investigations with Russian scientists in disaster-affected regions of the former Soviet Union.
Care is necessary because small children are approximately three times more sensitive to radiation effects than adults.
According to the results obtained thus far, even if an adult’s external dose in Iitate Village or a comparable location were assumed to be 3 millisieverts, the corresponding dose for a child, calculated at three times that level, would be equivalent to 9 millisieverts.
This can be regarded as within the safe range.
In reality, however, the true figures remain unknown because the government did not provide residents with personal dosimeters.
Japan possesses the scientific capabilities required to assess both external and internal exposure accurately, yet the Kan administration failed to use those capabilities.
That is the greatest problem.
As a result, the author believes that dubious and exaggerated dose estimates produced by the imaginations of non-specialists caused anxiety among large numbers of Fukushima residents and other Japanese citizens.
The scientific radiological-health examinations of Fukushima residents that the author has been conducting should henceforth be made available to all residents who request them, under the responsibility of the national government.
Under no circumstances should Fukushima residents be treated as guinea pigs.
The purpose must be to reassure individual residents by enabling each of them to know the low dose that he or she actually received.
A scientific project must also be launched immediately to restore agriculture and dairy farming, particularly in the area between 20 and 30 kilometres from the plant.
The national government must take responsibility for decontaminating the topsoil so that residents’ individual doses fall below 1 millisievert per year and caesium concentrations in agricultural products fall below the regulatory limits.
Otherwise, agriculture in Fukushima will collapse.
This was the proposal I made during my keynote scientific address at a symposium in support of Fukushima held in Tokyo on July 27.※10
Immediately afterward, I sent the proposal to the Prime Minister’s Office.
I hope that the new prime minister, Yoshihiko Noda, will demonstrate a strong commitment to Fukushima’s reconstruction.
Several topsoil-decontamination centres should be constructed within the 20-kilometre zone, and local residents should be employed there.
The resulting programme would lead to the reconstruction of agriculture and dairy farming.
Even if it costs one or two trillion yen, it should be done.
Let us demonstrate Japan’s scientific capabilities and determination to the world.
Japan should communicate to the world, through Fukushima’s reconstruction, the fact that Fukushima did not become another Hiroshima or another Chernobyl.
Doing so will help correct Japan’s distorted postwar attitude.

References

※1　Jun Takada, “The Cenotaph Inscription in Hiroshima Peace Memorial Park Should Be Removed,” Excellence Award, APA Group Third “True Interpretations of Modern History” Essay Competition, 2010.
※2　Jun Takada, Nuclear Weapons and the Sword, Meiseisha, 2010.
※3　Jun Takada, Fukushima: Falsehood and Truth, Iryo Kagakusha, 2011.
※4　Jun Takada, Survey of Radiation-Exposure Sites Around the World, Kodansha, 2002.
※5　Jun Takada, China’s Nuclear Tests, Iryo Kagakusha, 2008.
※6　Jun Takada, The Nuclear Desert and the Risks of Silk Road Tourism, Iryo Kagakusha, 2009.
※7　Jun Takada, Nuclear-Explosion Disasters, Chuko Shinsho.
※8　Kunihiko Takeda, How to Protect Children from Radioactive Contamination, Shufu-to-Seikatsusha, 2011.
※9　L. A. Ilyin, Chernobyl: Falsehood and Truth, Nagasaki Association for Hibakusha Medical Care, 1998.
※10　Jun Takada, keynote address at the Fukushima Support Symposium, Association for Supporting Fukushima through Humanitarian Science, 2011.