% *. rs wM ey af = ri ‘i i enna: : statistically significant difference in the number of mutations “t in the offsprings of irradiated parents as compared with offsprings of non-irradiated control parents, It did not prove in any sense of the word that there was no genetic effect, Following a general discussion of the mechanisms of genetic change especially as produced by radiation, both natural and artificial, the committee made certain recommendations, In doing so they used natural background radiation exposure (i.e,, radiation from cosmic rays, igneous rocks, radium and radtopotassium in our bodies, etc.,) and the so-called spontaneous mutation rate as base lines, In addition they were 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 3x 2, Medical x-rays 36r 3. Fallout from weapons testing if continued at rate for the past 5 years O,1ir (0,02 to 0,57) They then estimated that the exposure necessary to double the mutations rate in humans lay between 52 and 150r, more likely 30r to 80r, but also that different gene loci were quite different in thelr sensitivity to radiation, Taking these observations into consideration they felt that if the population as a whole were to ~~ Enclosure IT te