COMBINED EFFECTS OF ATOMIC RADIATION AND OTHER AGENTS IN HIROSHIMA AND NAGASAKI AND POSSIBLE APPLICATION OF FUZZY THEORY

摘要

The survivors of atomic bombings and those who visited Hiroshima and Nagasaki immediately after the atomic bombing could have been subjected to a number of other possible noxious effects in addition to atomic radiation. Hospitals, laboratories, drugstores, pharmaceutical works, storehouses of chemicals, factories, etc. that were situated close to the hypocenter were all completely destroyed and various mutagenic, carcinogenic or teratogenic substances must have been released; many doctors, nurses and chemists were killed. There was no medical care and no food in the region of high dose exposure and the drinking water was contaminated. There would have been various possibilities of infection. Mental stress would also have been much higher in the survivors closer to the hypocenter. It is confusing which factor played a dominant role. In addition, there would be problems in accurately identifying the position of the exposed persons at the time of the atomic bombing and also in estimating the shielding factors. There may be considerable uncertainty in human memory under such conditions. It is also possible that there could have been a large storage of gasoline to be used for transportation of army corps in Hiroshima. Therefore there is a possibility that various toxic substances, mutagenic or carcinogenic agents such as benzopyrene and other radiomimetic substances could have been released from various facilities which were destroyed at the time of the atomic bombing. Prof. Yoshiaki Yoshimi of Chuo University in Tokyo obtained an unclassified report of BCOF on Disposal Operation of Chemical Weapons of Okunojima island in Hiroshima while he was staying in the USA. The report is entitled "Disposal Report, Chemical Munitions, Operation Lewisite, BCOF OCCUPATION ZONE JAPAN, 8 May 1946 to 30 November 1946." As clearly stated in the above report, the Army Installation in central part of Hiroshima to which vesicants (Yperite and Lewisite) had been shipped had been destroyed by the atomic bombing. Judging from these findings it may be possible that some chemical weapons were released to the environment from the military facilities on ground and underground at the time they were destroyed by the atomic bombing and the survivors were exposed to poison gases to a smaller or larger extent. There was no drinking water and they had to drink rain water which fell heavily soon after the atomic bombing. It is highly possible that the rainwater was also contaminated by various toxic substances including chemical weapons. These effects combined with the irradiation by atomic radiation are difficult to quantify accurately at present, many years after atomic bombings. But if all these adverse effects were ascribed solely to the ionizing radiation, the effects of radiation may be overestimated in Hiroshima and Nagasaki. In using the Hiroshima and Nagasaki data for establishing radiation standard in peaceful uses of atomic energy, we should keep these possibilities of over-estimation in mind. According to Mr. Hatsuichi Murakami, ex-director of the Okunojima Chemical Weapons Museum, soon after the atomic bombing, some chemical weapons leaked into the sea from the facility on Okunojima and many fish were dead and floating on the water and washed to the shore. Normally, such contaminated dead fish are not consumed, but because of the extreme shortage of food at that time they were distributed in Hiroshima Prefecture. What effects it might have had is difficult to estimate. Under these situations we must consider the possibilities of combined effects of various uncertain factors and that there would be not only randomness but also fuzziness included in the uncertainties associated with the estimation of the radiation dose-effects relationships in Hiroshima and Nagasaki.