Genetical Effects of Radiations from Products of Nuclear Explosions

Abstract

I MUST thank Prof. F. W. Spiers for pointing out some of the errors in the basis on which I suggested in 1948 that most human mutations might be due to the action of photons or particles of high energy. Perhaps, however, he was not quite accurate in writing of my “contention that natural radiation accounts for most human mutation”. I stated that this was “quite possible”, and still hold that opinion. Further, his estimate of the dose received by Drosophila may be a little low, since the larvæ spend their life embedded in a medium containing appreciable amounts of potassium. Wright¹, in rough agreement with Spiers, has suggested that about 0.00015 of mutations in Drosophila melanogaster are due to radiation and rapid particles. Thus my provisional figure of 20 per cent should probably be reduced to about 2.5 per cent. But Russell² finds a mean mutation-rate at seven mouse loci of 2.5 × 10⁻⁷ per roentgen, which is about fifteen times the rate in Drosophila. This suggests that 30–40 per cent of human mutations might be due to high-energy events. Since these estimates are extremely uncertain, I still do not think it impossible, or even very improbable, that most human mutations may be so caused. This hypothesis gives an upper limit to the possible harmful effect of induced radioactivity. Even if, as I hope, this limit is too high by a factor of ten or even a hundred, it seems worth stating, if only because, while suggesting a more serious situation than some physicists have calculated, it decisively negates prophecies of wholesale racial degeneration resulting from experimental atomic explosions.