Attrition in the Hiroshima Adult Health Study: First Cycle Analysis **

The Atomic Bomb Casualty Commission (ABCC) is an epidemiological research institute in Hiroshima and Nagasaki, cooperatively sponsored by the United States National Academy of Sciences and the Japanese National Institutes of Health of the Japanese Ministry of Health and Welfare to investigate the sequelae of radiation upon man. One phase of the comprehensive program,' designed to study the late effects of nuclear radiation is the Adult Health Study,2 a continuing medical examination program involving approximately 20,000 individuals, both exposed and nonexposed, in Hiroshima and Nagasaki. The present report is concerned with attrition in the Hiroshima population only, for first complete cycle of examinations. In July 1958 ABCC embarked on a new and completely reorganized program in which the major emphasis was directed toward the detection of late radiation sequelae in the survivors of the atomic bombings. The Adult Health study sample was selected as a subsample of a large "master sample population" which had been obtained from several sources, including various censuses, the details of which are published in the report of Beebe, Fujisawa and Yamasaki.8 The medical subsample consists of four groups matched by age and sex: Group 1: Exposed within 2,000 meters of the hypocenter with acute radiation symptoms in 1945. Group 2: Exposed within 2,000 meters of the hypocenter without acute radiation symptoms in 1945. Group 3: Exposed 3,000-3,499 meters from the hypocenter. Group 4: Nonexposed, 10,000 or more meters from the hypocenter or not ifl the city at the time of the bombing.