Host: The Japan Radiation Research Society, Chairman of the 52nd Annual Meeting, Toshiteru Okubo (Radiation Effects Research Foundation)
It is known that people who entered into the ground-zero area after the atomic bombings in Hiroshima /Nagasaki soon suffered from various diseases. Although a possibility has been pointed out that these diseases were caused by residual radiation, the information was too fragmentary to consider the casual relation between diseases and radiation. A NHK TV program in August 2008 showed individual records of early entrants interviewed around 1950 by medical staffs of ABCC. According to these records, such diseases as fever, diarrhea, epilation etc. were registered. This year we met two entrants in Hiroshima who had individual records at ABCC. We estimated their external exposure, taking into consideration their behaviors after entering the city. About 30 mGy was estimated for Ms A, who entered on August 7 in Otemachi (900 m from the hypocenter) and stayed for one week at Bunridai (1,400 m). Fever, diarrhea, sore mouth etc. appeared with her on August 13. Bleeding gums and epilation began at the beginning of September 1945. About 8 mGy was estimated for Ms. B, who walked on August 7 from Hijiyama to Koi station. She suffered from vomiting and bloody diarrhea on September 12 and epilation began on October 5. Although these diseases recall us radiation syndrome, the level of their radiation exposure seems to be too small to cause such diseases. We are considering three possibilities. (1)Observed diseases were not related with radiation, but with other factors such as fatigue or infection, (2)Radiation exposure was mistakenly underestimated, (3)Under the extreme condition of atomic bomb, synergistically working with other factors, threshold for radiation syndrome could be drastically reduced.
