Epidemiology of aplastic anemia in Japanese radiological technicians

Among Japanese radiological technicians, four deaths from aplastic anemia have been recorded. Based on this fact, some epidemiological considerations are tried. During the period from 1930 to 1960, the population of radiological technicians is estimated to be 74,400 man-years, in which 0.5 aplastic anemias are expected. However actually three died from aplastic anemia. This difference is statistically significant at the 1% level. On the other hand, in the period from 1961 to 1973, the observed value is 1 against 0.7 expected. It is concluded that aplastic anemia had been frequently induced among Japanese radiological technicians in the era when there was much exposure to occupational radiation. (auth.)