Abstract
Three workers were heavily exposed to radiations in the Tokaimura nuclear accident, and one of them died due to the acute effects of radiations. Doses for the heavily exposed persons were estimated to be 2.5, 10 and 18Sv, according to the Science and Technology Agency. Workers who tried to stop the chain reaction by breaking the water pipe were estimated to have been exposed up to 120mSv. Possible doses for other workers and residents in the neighborhoods were estimated to be less than 10mSv, with a few workers with slightly higher film badge records. After the accident, many reports in mass-media warned that the exposed persons may develop cancers and leukemias in future and follow-up healthcare should be needed. Judging from our knowledge of the extensive epidemiological survery of the atomic bomb survivors in Hiroshima and Nagasaki, these reports are very misleading. There would be absolutely no or extremely small possibility of developing any health hazard among the workers and the residents except for the three unfortunate heavily exposed workers. If so-called follow-up health checks would involve x-ray diagnosis for cancers, the radiation doses by the diagnosis would exceed the exposure by the accident. Also, the test for the DNA damage applied to some workers and residents is not reliable at all, and could cause unnecessary fear among the persons who were mistakingly said to be of high-risk.
