Evaluation of delayed effects of ionizing radiation: an historical perspective.

It is widely assumed that after the bombing of Hiroshima and Nagasaki there were no lasting effects of the acute injuries (which included extensive damage to blood forming tissues by the radiation) or the massively high death rate (which was caused by environmental effects of the blast as well as personal injuries). However, close inspection of the dose response curves for non-cancer deaths has shown that this could be a false impression caused by one effect of marrow aplasia being confused with leukemia (defective erythropoiesis) and a second effect being confused with early selection in favor of general fitness (defective immune responses). Possible consequences of such confusion (for cancer risk coefficients) are discussed in relation to what is known about late effects of prenatal x-rays and occupational exposures to radiation.