Leukaemia in Nagasaki atomic bomb survivors from 1945 through 1959.

This review of the Nagasaki leukaemia experience during a period of 14 years after the detonation of the atomic bomb, together with comparisons with data from Hiroshima and from other series of post-radiation leukaemia cases, again demonstrates beyond reasonable doubt the leukaemogenic effect on man of ionizing radiation. An increased risk of leukaemia following doses probably as low as 100 rads (air-entry dose) of whole-body radiation is demonstrated on the basis of the available estimates of atomic bomb radiation doses. At doses above this level the increase in leukaemia incidence may be linearly related to the radiation dose. The data are too limited to allow of an evaluation of the risk represented by doses at the lower levels of radiation; but it seems clear that, if a threshold dose for leukaemia induction exists, it is lower than the threshold dose for the clinical expression of acute radiation syndrome.The sex and age distribution of radiation-induced leukaemia and the types of leukaemia observed are also discussed.