Technical Report No. 19-88
In vivo mutant T cell frequency within assigned dose groups in atomic bomb survivors carrying extreme dose-specific values of chromosome aberration frequency
Hakoda M, Akiyama M, Hirai Y, Kyoizumi S, Awa AAEditor’s note: A publication based on this report was published in Mutat Res 202:203-8, 1988
Summary
The objective was to investigate whether there is a positive association between frequencies of HPRT– T cell mutations and chromosome aberrations among atomic bomb survivors at a given dose. This would provide evidence regarding whether individuals vary in their sensitivity to radiation. The approach was to compare T cell mutant frequencies (Mf) among survivors who have unusually high- and low-chromosome aberration frequencies, in relation to their radiation dose. Within each of four dose groups (1-99, 100-199, 200-299, and 300+ rad) equal numbers of survivors were selected who have unusually high and unusually low chromosome aberration frequencies for the dose group. The total numbers selected from each of the dose groups were 8, 8, 8, and 16, respectively. Within each dose group, the mean doses for the high- and low-aberration subjects were very similar. The difference between T cell Mf of the high- and low-chromosome aberration groups was tested by a t-test on the logarithms of the frequencies, stratifying on dose groups. The Mf of the high-aberration group was significantly higher than that of the low-aberration group (p = 0.01). However, at least part of this positive association may be explained by imprecision in the dose estimates. This is because among survivors at the same estimated dose, it can be expected that those with high-aberration frequencies may have higher true doses than those with low-aberration frequencies. Presently not enough is known about how to determine whether it could entirely explain the positive association seen between frequencies of mutation and chromosome aberration among those at similar estimated doses.
The objective was to investigate whether there is a positive association between frequencies of HPRT– T cell mutations and chromosome aberrations among atomic bomb survivors at a given dose. This would provide evidence regarding whether individuals vary in their sensitivity to radiation. The approach was to compare T cell mutant frequencies (Mf) among survivors who have unusually high- and low-chromosome aberration frequencies, in relation to their radiation dose. Within each of four dose groups (1-99, 100-199, 200-299, and 300+ rad) equal numbers of survivors were selected who have unusually high and unusually low chromosome aberration frequencies for the dose group. The total numbers selected from each of the dose groups were 8, 8, 8, and 16, respectively. Within each dose group, the mean doses for the high- and low-aberration subjects were very similar. The difference between T cell Mf of the high- and low-chromosome aberration groups was tested by a t-test on the logarithms of the frequencies, stratifying on dose groups. The Mf of the high-aberration group was significantly higher than that of the low-aberration group (p = 0.01). However, at least part of this positive association may be explained by imprecision in the dose estimates. This is because among survivors at the same estimated dose, it can be expected that those with high-aberration frequencies may have higher true doses than those with low-aberration frequencies. Presently not enough is known about how to determine whether it could entirely explain the positive association seen between frequencies of mutation and chromosome aberration among those at similar estimated doses.