Fukushima daiichi nuclear accident and radiation health risk

Explained are circumstances of the title Accident and concurrent commentary of radiation health risk concerning the exposure, moral from Chernobyl Accident, present state of risk assessment, and project of Fukushima Health Management Survey. The author points out it important that bases of scientific and political standards and decisions made by UNCEAR, ICRP and IAEA have essentially stood on results of previous acute radiation exposure in Hiroshima and Nagasaki. He discusses about the dose limit 1 mSv/y to the Japanese public in relation to its and global averages of natural radiation dose ca. 1.5 and 2.4 mSv/y, respectively, and mentions about the educational importance for recognition of the exposure. Chernobyl Accident teaches that carcinogenic risk is now insignificant among several million residents exposed with up to several tens mSv and significant increase of childhood thyroid cancer incidence is clear due to internal exposure with radioiodine, and that the most serious problem is mental one evoked in general public. Following Fukushima Accident by the Quake and tsunami on 3.11, there are repeated instructions of evacuation to residents within the area 3 km distant from the power station, then 10 km, 20 km to outside the area, and 30 km to indoor. Later, areas recommended for evacuation are spread, and grounds in limited zones and in certain foods are found contaminated by Cs-137, to which response is being taken by authorities. Radiation by IAEA evaluation is at Level 7 although the amount of total radioactive substances released in air is estimated to be about 10% of that in Chernobyl Accident. Rearrangement of medical system is thought necessary for objective evaluation of health risk reliable to public. The project of Health Survey stands on Fukushima Medical University in contract with the Prefecture and in relation with concerned government authorities to begin to investigate the whole prefectural people from August 2011, when this paper is published. (T.T.)