Abstract
We estimate radiation dose using enamel of molars donated by atomic bomb survivors in Hiroshima by electron spin resonance (ESR) technique. In the present study, we conducted ESR measurements of 92 molars and compared the results with chromosome aberration frequencies (by FISH method and/or Giemsa method) of the same survivors. Both ESR signal intensity and chromosome aberration frequency were used to calculate 60Co gamma-ray equivalent dose. FISH data and Giemsa data fitted closely in 37 individuals who were examined by the two methods. We decided to use FISH data of these cases. Among a total of 92 survivors (35 had only Giemsa data, 20 had only FISH data, and 37 had both data sets), we found that ESR dose and chromosome dose showed a close association in the majority of cases. There are a few exceptions, however. Seven survivors showed substantially lower ESR doses than corresponding chromosome doses. Scince most of the samples were wothdom teeth ot the donors were exposed to the bomb below age of 5years old, we think that molars examined were not probably established at the time of the bomb. On the other hand, nine survivors showed considerably higher ESR doses than corresponding chromosome doses. Their histories of medical exposure are being investigated but so far we found no evidence for the exposure. When ESR doses or FISH doses were compared with DS02 gamma-ray doses, the individual points showed a wider distribution. Because the biodosimetric endpoints by the two completely different methods (ESR and FISH) fitted closely to each other, it seems that the results validated the two methods each other, which may allow us to use chromosome data which had already been obtained from 4000 A-bomb survivors, and may be able to indicate possible extent and direction of dose bias in the DS02 individual doses.
