Published on Apr.17 ,2013 : The Denki shinbun(The Electric Daily News)
Shojiro Matsuura
Chairman of JANSI

Needless to say, we live in a world surrounded by many kinds of risks. The common tools we use and even water, air and sunlight, which are essential to life, can be a risk that could cause physical disorder at times. However, we are naturally aware of such risks with our five senses. Creating some kind of assessment standard in which we estimate such risks, we live our everyday lives based on such standard.

And yet, even though radiation exists in any part of the Earth, we have not developed senses concerning radiation over the course of evolution. Therefore, we do not have the ability to estimate radiation damage risks with our five senses. In addition, since it is not often that we see people with radiation damage, most people have little experience in directly hearing actual cases of radiation damage. In other words, we were unable to gain senses of safety and protection that allow us to make a satisfying judgment on a certain level of radiation exposure as not giving an impact, as we live a normal everyday life.

As Torahiko Terada has said, “it is easy to fear something more than we should or not fear at all, but it is difficult to fear something appropriately.”

On the other hand, I hear that it is commonly recognized among experts on radiological consequence evaluation that “below 100mSv/year, which is the radiation range where probabilistic and definitive impact does not significantly exist, is the low radiation range” based on the research results of the vast amount of experimental and epidemiological data on radiation impact.

I personally had a peculiar experience of radiation impact by coincidence in third grade at the national elementary school (1943). In the midst of World War II, sanitary conditions of the barber shop were poor due most likely to supply shortage, which resulted in an endemic of head skin disease caused by Tinea capitis (scalp ringworm). I also had Tinea capitis, so I went to the dermatologist but it did not get any better. My father, who feared for my symptoms to worsen, told my mother to get me to receive treatment from the special clinic where Tinea capitis was treated using X-ray. I received X-ray radiation three times at the clinic my mother took me to. As the doctor notified me before the treatment, all the hair on my head fell out, but after some period of time, downy hair began to grow and eventually all my hair grew back. I now have gray hair, but not so much less hair.

After becoming a specialist in nuclear energy, I estimated the exposure dose of that treatment. My estimation was that I received at least 1,000mSv on my head and at least 100mSv on my entire body. Based on my own experience, I accepted setting 100mSv as the low radiation level.

Dr. Tamiko Iwasaki, who is a specialist on radiological consequence evaluation and whom I had previously received teachings from, recently gave me a document from which I learned that 200,000 children in the world had received the same kind of treatment in those days. Of those children, exposure of the approximately 13,000 children who received the treatment at New York University was 3,000 to 3,800mSv. The highest recorded was 6,000mSv. It was also concluded that when those children received eye examination 15 and 25 years later, no functional disorder was found. Leukemia is somewhat questionable, but statistically significant difference has not been found for the occurrence of thyroid cancer.

According to Dr. Iwasaki’s experimental survey results, more than half of personnel engaged with nuclear energy recognize around 10mSv to be the low radiation level. There is a 10 times difference with the recognition of specialists. One of the greatest challenges post-Fukushima may be to amplify to the general public a “respectable level of evaluation standards” for risks of radiation damage. Scientific knowledge to take on this challenge is available any time.

end