Leukemia in Man Following Exposure to Ionizing Radiation

Abstract

The occurrence of leukemia among survivors of the atomic bombings in Hiroshima and Nagasaki, Japan, was tabulated over the years from 1945 through 1958. The 209 confirmed leukemia cases which have occurred have been related to closed population samples in order to establish yearly incidence rates and to determine the dose-response relationship. The data indicate that the incidence of leukemia in an irradiated population is dependent on dose in a roughly linear manner from 100 rad to 500 rad. The data do not allow a positive statement with regard to the presence or absence of a threshold for leukemia. There is evidence that males and the younger age groups are more sensitive to leukemia induction. Latent period for leukemia is approximately 1.5 to 2 years with a maximal incidence occurring 4 to 8 years following exposure. A rough approximation of leukemia risk of 1 to 2 cases per million population per year per rad can be inferred from the data. This latter figure needs to be viewed with much reservation in view of differing sensitivities to leukemia induction within a population. The data from the 2 cities are compared and agree reasonably well with other series of radiation-induced leukemia.