Japan is now in the process of recovering from the natural and nuclear disasters that hit the Tohoku region six months ago. It is apparent that reconstruction efforts are being made everywhere and things are gradually getting back to “normal,” as the damaged nuclear reactors are almost under control and radiation levels are noticeably receding in the atmosphere of major cities in the Tohoku-Kanto regions as well as in the nation as a whole in terms of detected radiation contained in food and other materials.
However, concerns about radiation contamination among many people seem to be increasing rather than decreasing, and are rapidly becoming a serious obstacle to further recovery from the emergency situation in Japanese society. For example, an increasing number of consumers are avoiding eating various vegetables, fish, meat, and even rice, at least of this year’s crop, if there is any trace of radiation detected in such food items, often ignoring the government’s announcement that they are safe enough to eat by any reasonable standard.........Another example is the case of school playgrounds, where many parents are extremely reluctant to let their children play, although the radiation level detected in their school playground is less than the official limit. As a result, the official limit itself has recently been reduced to a lowest possible level to satisfy those concerned parents, but on the other hand, more schools are facing a real dilemma between the merit of physical activities in playgrounds for children and the demerit of radiation exposure as perceived by parents.
Why do such serious concerns and fears persist among so many people? There seem to be a number of reasons. First, people no longer trust the government due to its mishandling of the nuclear power accident, and have become extremely skeptical about the government’s announcements and decisions on nuclear safety issues. Another possible reason is that because there are so many unknowns and, therefore, so many different opinions regarding radiation risks, even among nuclear specialists, people are confused about possible health hazards of radiation exposure and tend to side with the worst case scenario just in case. While some people may be acting “rationally” for these reasons, many others simply seem to be overreacting and overly concerned about nuclear radiation, possibly interfering with Japan’s recovery process and adding to negative publicity about Japan overseas. Then why are such concerns and fears among those people still increasing, rather than decreasing, over time, even though more and more objective information about radiation is becoming available?
One plausible explanation is that according to some recent studies on irrational human behavior, often explained in behavioral economics, people tend to be more afraid of negative effects such as the health hazards of possible radiation in playgrounds than they should be, even though there can be larger positive effects such as physical exercises for school children. Also, people tend to believe that negative events such as cancer risks due to radiation are more likely to happen than they actually do, while they tend to think that positive events such as improved health due to physical exercises are less likely to happen than they actually do. As a result, there is a tendency for the general public to be more and more cautious about radiation risks, and to request more and more rigorous restrictions to be adopted to avoid negative effects of radiation as perceived by themselves, even though objective information seems to imply otherwise.
To overcome such subjective biases among the general public, it is not good enough to have information disclosure about factual matters and public announcements about safety standards. What is urgently needed is to let the public know relevant facts put in the proper context, for example, living in a certain location with a certain level of radiation would be as risky as a certain degree of obesity, lack of exercise or smoking in terms of the probability of cancer and other illnesses. In such proper context, people can make more rational decisions by taking account of various possibilities, rather than being obsessed only with radiation risks out of context, leading to irrational decisions with much worse health hazards than otherwise. After all, rational decisions based on objective information are essential not just on the radiation problem but on broader issues such as the nuclear energy policy for Japan in the future. ---------------------------------------------------------------------- (Japanese) 「放射線への過度な懸念の克服に向けて」 宮尾尊弘（筑波大学名誉教授） http://www.esuj.gr.jp/jitow/jp/contents/0333.htm