Studies of the Mortality of A-Bomb Survivors: 3. Description of the Sample and Mortality, 1950-1960

Abstract

The Life-Span Study is a basic component of the program of studies of the survivors of the Nagasaki and Hiroshima atomic bombs conducted jointly by the Japanese National Institute of Health (JNIH) and the Atomic Bomb Casualty Commission (ABCC). Details of the sampling procedures and methods of follow-up have been specified in previous reports (1, 2) and will be only briefly mentioned here. The sample consists of nearly 100,000 persons whose names were drawn from various censuses and listings, notably supplementary schedules to the 1950 Japanese National Census. All eligible persons who were located within 2500 meters of the hypocenters at the time of the bombing (ATB) and whose names were found on the listings are included in the sample. More distally located persons and persons not in the cities at the bombing were sampled at random from among those eligible to provide comparison groups. Each sample member has been the subject of field interview to ascertain eligibility and to obtain details of exposure. Mortality information is obtained from the family registers (koseki) maintained by Japanese municipal offices, and cause of death from an abstract of the Japanese Vital Statistics Death Schedules. Tests have shown that these sources provide information for more than 99 % of deaths (1). Cause of death as given on the schedule is coded according to the World Health Organization International Classification of Diseases (3).