Abstract
Recent studies concerning radiation risks to man by the Committee on Biological Effects of Ionizing Radiation of the National Academy of Sciences.sbd.National Research Council and the United Nations Scientific Committee on the Effects of Atomic Radiation emphasized the need for estimates of dose to organs of the Japanese atomic bomb survivors. Shielding of internal organs by the body was investigated for fission weapon .gamma.-rays and neutrons, and ratios of mean absorbed dose in a number of organs to survivors'' T65D assignments of tissue kerma in air were provided for adults. Ratios of mean absorbed dose to tissue kerma in air were provided for the thyroid and active bone marrow of juveniles. These organ dose estimates for juveniles were interesting in studies of radiation risks due to an elevated incidence of leukemia and thyroid cancer in survivors exposed as children compared to survivors exposed as adults.