There will be no negative effects on health in Fukushima
Scientist Kunihiko Takeda views the fact that the government has raised the yearly exposure limit for the victims of this disaster to 20 millisieverts as a problem. He said, “After the Chernobyl accident, children developed cancer starting four years from exposure.”＊8 Although it is not clearly stated, he is referring to thyroid cancer. The problem is that he causes misunderstanding among his readers by leading them to believe that cancer can occur from such low doses of radiation. In the area around Chernobyl, such sickness occurred because the thyroid glands of people were exposed to up to 50 sieverts (although most were exposed to just several sieverts). There were around 100,000 children in Belarus. Among these, four people developed cancer after four years, while a maximum of 13 people developed cancer after nine years. Afterwards, these numbers declined.
In the case of Fukushima, the thyroids of residents have been exposed to low levels of radiation between 1/1,000th to 1/10,000th the amount in Chernobyl. Among the 66 people I examined the maximum dose was eight millisieverts. Based on radioactivity dosage, the risk of Fukushima residents developing thyroid cancer is less than one person per 10 million per year. Since the population of Fukushima Prefecture is two million, thyroid cancer will not result from these low doses. Truly, people with only amateur knowledge of radioactivity need to stop paralyzing the citizens of Fukushima and the entire country with fear. Regarding external exposure of the entire body, the largest dose among those evacuated from the 30-kilometer area around Chernobyl was quite high at 750 millisieverts over a period of seven days＊9. In contrast, the dose for people subjected to emergency evacuation from the 20-kilometer area around the Fukushima nuclear power plant, based on my predictions from transitions in the outdoor air dose rate at the time, was a few millisieverts ‐ less than 1/100th the dose at Chernobyl. For that reason, it’s practically a crime to make people from Fukushima and other parts of Japan fear health effects based on the damage that occurred at Chernobyl.
We know that the ovaries of females can be affected at a level of 650 millisieverts or greater, so it’s true that terrible things happened to the people evacuated from the 30-kilometer area around Chernobyl. However, it is possible to affirm that absolutely no such risk is posed to Fukushima or other prefectures.
I believe there are almost no residents of Fukushima Prefecture who have reached the level of 20 millisieverts per year. The estimated dose in Fukushima over 30 days, according to personal dosimeter calculation values from when I carried out my surveys, was 1.0 millisieverts or less in the 20-kilometer area around the plant and its surrounding area from April to May, and also from June to July, while the dose in the area between Aizu and Fukushima City was 0.10 millisieverts or less. From the above, I estimate that the annual external exposure for citizens of Fukushima Prefecture in 2011 will be 10 millisieverts or less, while most people will be exposed to five millisieverts or less.
Scientific evaluations could be obtained by having everyone ‐ from children to adults ‐ wear personal dosimeters. However, the government’s disaster countermeasures office did not do this during the initial period between March and May, when radiation doses were comparatively high. This was a truly careless mistake, especially considering that people in Iitate Village were being advised to take shelter indoors.
From the aforementioned actual values taken by personal dosimeter, my tentative estimate of most Fukushima Prefecture residents’ external exposure to radiation in 2011 is several millisieverts.
Jun Takada (57)
Doctor of Science Professor, Sapporo Medical University