statisticall:: significant difference i1 the number of mutations BS : 0. - + sflaul -w. . springs of nox-ipradiated control parents, It did not prove in _ any sense of the word that there was no geretic effect. Following a general discussion of the mechanisms of senetic . change especially as produced by radiation, both natural énd artificial, the comnittee made certain recommendations. in doing , t so they used natural background radiation exposure (1.€.5 radia- tion from cosmic rays, igneous rocks, radium and radfopotessium in our bodies, etc.,) and the so-called spontaneous mutation rate as base lines, - In addition theywere unanimous that no increase in the spontaneous mutations rate was desirable and that all radiation exposure to the germcells at whatever rate of exposure did indeed increase the mutation rate in proportion to the total exposure received at the time of conception, Consequently they stated that all radiation exposure to the gonads was detrimental and consequently radiation exposure should be kept at the minimum consistent with the over-all needs of a society. They then observed that half of the American children were born of parents approximately 30 years of age or less, They noted that by the age of 30 the average American would receive germ cell exposures as follows: 1. Background or natural radioactivity 43x 2, Medical x-rays 3.7 3, Fallout from waapons testin, if continued at vate for the past 5 years O,ir (0,02 to 0,5r) They then estimated that the exposure necessary to deuble tne piviticne rate in hunans lay betwee: 5€ and 150r, more likely 20r to €tr, pet also that different pent loti were euite different “Lasitivicy fo rediation, Po Gbe Tak g visee observations ints pom cert bss as a winks) ‘

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