He is a 38-year-old male atomic bomb survivor. He is recovering from radiation sickness of A-bomb disease about 3 months after the atomic bomb was dropped. He showed necrosis of the oral gums and mandible.

　　He is a 38-year-old male atomic bomb survivor. He is recovering from A-bomb radiation sickness. He was photographed approximately 3 months after the atomic bomb was dropped. He showed necrosis of the gums and mandible in the oral cavity.

　Ulceration of the mucous membranes, including gingivitis, stomatitis, and pharyngitis, was common in more severe cases of A-bomb disease. Clinical manifestations were similar to those of leukopenia. It was customarily accompanied by hemorrhagic diarrhea, which was difficult to assess because in many cases it was due to contagious inflammation. Petechiae may appear on the mucous membranes at the onset of gingivitis. However, skin hemorrhage appeared much later. Based on the data collected in Hiroshima, most cases occurred within a radius of about 1.5 km from the hypocenter.

　The U.S. Strategic Bombing Survey Group was formed on November 3, 1944, under orders from President Roosevelt. President Truman ordered an investigation into the effectiveness of air raids against Japan on August 15, 1945. The U.S. Strategic Bombing Survey Group for the war against Japan consisted of about 300 civilians, 350 officers, and 500 enlisted men. Starting in early September 1945, about a month after the atomic bombs were dropped, branches were established in Nagoya, Osaka, Hiroshima, and Nagasaki, with Tokyo as the base. The materials collected by the survey team were transferred to a permanent government agency, which conducted on-site surveys in the A-bombed cities of Hiroshima and Nagasaki for approximately 10 weeks from October to December 1945. The survey team collaborated with other survey organizations such as the Joint Conference on Atomic Bomb Surveys of Japan, the Anglo-Japanese Survey Mission to Japan, and the Japanese Naval Technical Survey Mission to Japan.

　There was no record of the cause of death of those who died immediately after the atomic bombs exploded. Radiation does not cause death immediately, and deaths from exposure to the atomic bombs are caused by other factors of injury. The Hiroshima Prefectural Health Bureau estimated that about 60% were burns (flash or fire burns), about 30% were falling debris, and about 10% were other injuries. Other estimates were that about 50% were due to burns and about 50% were other physical injuries.

　For survivors very close to the hypocenter who suffered neither flash burns nor secondary injuries, A-bomb sickness developed within two to three days, causing hemorrhagic diarrhea and acute inflammation of the upper respiratory tract and gastrointestinal mucosa. Some died within two to three days of developing A-bomb sickness. Most of the survivors died about a week later. The Japanese investigators had difficulty in proving significant changes in the blood in survivors who died within a short period of time.