The pathologic effects of an instantaneous dose of radiation.

The distinctive feature of the atomic bomb is the large amount of radiant energy that it produces. While this energy covers a wide range of the electromagnetic spectrum, its chief physiologic and pathologic effects may be divided into two groups: first, the effects of heat, producing primary thermal injury of the flash burn type, and secondary thermal injuries due to induced fires; second, the effects of short-wave radiation and neutrons, paralleling closely the effects familiar to us from the experimental studies of the biologic effects of x-rays. This radiant energy was produced in an instant. Security prevents statement as to the exact duration of time. Of course, combined with and modifying and obscuring these effects are the more usual effects of the conventional types of bomb. Chief among these is air blast injury, almost always secondary, due to flying debris or impact against fixed structures. In our studies of the atomic bomb effects at Nagasaki and Hiroshima, which were carried on under the direction of the Naval Medical Research Institute and the Naval Technical Mission to Japan, we concentrated particularly on the injuries due to radiation. For security reasons the type and quantity of this radiation cannot be discussed. Suffice it to say that radiation effects ranging from lethal to minimal were observed. We were very fortunate in our study to have the collaboration of the investigating group from the Manhattan District under Colonel Stafford L. Warren and the Joint U. S. Army Imperial Japanese Government Atomic Bomb Commission under Colonel A. W. Oughterson.