Shunichi Yamashita, a professor of radiation medicine at Nagasaki University who became adviser to Fukushima Prefecture on radiation health risk control, says people should be "properly afraid" of the risk of radiation exposure from the quake-stricken Fukushima nuclear power plant and take precautionary steps.
Shunichi Yamashita, a professor of radiation medicine at Nagasaki University who became adviser to Fukushima Prefecture on radiation health risk control, says people should be "properly afraid" of the risk of radiation exposure from the quake-stricken Fukushima nuclear power plant and take precautionary steps.
Yamashita, who also serves as director of the WHO collaborating center for research on radiation emergency medicine, has provided medical support since 1991 to people in the former Soviet Union who suffered from radiation exposure due to the 1986 Chernobyl nuclear power plant accident.
Excerpts of his interview with The Asahi Shimbun follow:
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Foods and drinks found with radioactivity levels above the acceptable standards must not be eaten or distributed. Of that we must make certain.
Iodine up to 17 times the acceptable level has been found in milk in Fukushima Prefecture and up to 27 times in spinach in Ibaraki Prefecture. They are at levels that will not affect health when consumed only once, but they had better not be eaten from now on.
In Fukushima, up to 308 becquerels of iodine-131 was detected in 1 liter of water (compared with the health ministry's acceptable level of 300 Bq). But it would pose no health risks because people would not drink liters of water in a single go.
One area that I pay close attention to is the effect of radioactive pollution of the air on children's thyroid glands. Some areas of Fukushima Prefecture recorded 100 microsieverts per hour of radioactivity. Because only one-10th of radiation is usually absorbed into a person's body, at that level, the total intake would be 10 microsieverts per hour, or 240 microsieverts a day. That is still about one-200th of the level at which iodine preparation should be given (to prevent thyroid gland disease).
Nevertheless, it is not good for infants and young children, who are more vulnerable, to remain in the area.
Currently, people in the 30-kilometer range have been told to evacuate (from a 20-kilometer radius of the plant) or stay indoors (in the 20-30 km range), and I think it was an appropriate decision. Compared with the Chernobyl nuclear power plant disaster of 1986, the level of radiation leaked has been far smaller. At this time, it is not necessary to expand the evacuation area further.
At Chernobyl, the reactor core was exposed, causing it to spew out a large quantity of radioactive substances into the air for one week. In some areas, the rate of thyroid cancer incidence among those who were children at that time was 100 times higher than normal. It was not due to the radioactive materials in the air. It was apparently because many people continued to consume polluted milk and other foods for a long time without taking precautions. This was because no proper information was given to residents in affected areas.
It is necessary to be properly afraid of radioactivity. I will give advice to the prefecture so the public authorities will provide objective data swiftly to residents. That way, they will be able to maintain a relationship of trust with residents.