Reassessment of Atomic Bomb radiation dosimetry

Extensive work has been conducted over the past several years to reassess all aspects of the radiation dosimetry for the A-bombs in Hiroshima and Nagasaki. This work has included reviews of the bomb yields, source terms, air transport of neutrons and gamma rays, neutron-induced radioactivity and thermoluminescence produced by gamma rays in exposed materials, shielding of individuals by buildings, and calculations of organ doses. The results of these theoretical and experimental activities have led to the development of a new dosimetry system which is designated as the Dosimetry System 1986 (DS86). To be useful in radiation risk assessment, DS86 must be individualized or applied to the assertions of particular individuals as to their whereabouts at the time of the bombing. New DS86 estimates, in terms of tissue kerma in air and absorbed dose to fifteen organs, are available for 106,001 of the 141,635 individuals in current follow-up study populations. For the other individuals, it has been impossible to make DS86 estimates for 9,026 exposed individuals, and there are 26,608 unexposed individuals who were not in either city at the time of bombing. The DS86 estimates are discussed and compared with early dose estimates which were designated as Tentative 1965 Doses (T65D) and were used as a basis for radiation risk assessment throughout the 1970's