The LD50 associated with exposure to the atomic bombing of Hiroshima and Nagasaki.

Numerous attempts have been made to estimate the distance at which 50% of the individuals exposed to the A-bombing of Hiroshima and Nagasaki died, ostensibly from their exposure to ionizing radiation. It is difficult to convert most of these distance estimates to a dose-related LD50, since radiation shielding was ignored. The recent reassessment of the atomic bomb radiation dosimetry has provided an opportunity for the estimation of the bone marrow LD50. There is a surprising concordance in the various estimates that have been made given the different groups of survivors involved and the methods used to estimate the LD50/60.