Dees HII SO 340 RADIATION STANDARDS, INCLUDING FALLOUT Since the time of the last hearings on fallout before this committee, much attention has been centered on the hazards posed by the production of carbon 14 as a product of nuclear detonations. No exact appraisal of this hazard can be given at the present time, but it is clear that estimates of genetic damage must be revised upward because of the ready incorporation of carbon 14 into living tissues and into the hereditary materials themselves, and because of the long half-life of carbon 14. The recently issued new edition of “The Effects of Nuclear Weapons” places the dosage of emitted beta radiation from carbon 14 as equal to that from cesium 1387, although delivered at a very much lower dose rate; and the genetic damage from transmutation of carbon 14 into nitrogen 14 as equal to that from the emitted beta radiation. Isee no reason to differ with these estimates. There are other recent findings which increase our estimates of genetic damage done by atomic radiations. At the Oak Ridge National Laboratory, D. L. Lindsley has shownthat in the fruitfly many lethal mutations remain undetected in the usual method of screening for sex-linked recessive lethals. Estimates of the total number of lethal mutations produced by a given dose thus need to be increased by 20 percent. Findings such asthis one and the role of carbon 14 in the production of genetic damage tend to offset the reduction in the estimates of overall genetic damage which derive from the knowledge that low dose rates, with which we must be mainly concerned, are much less potent in producing mutations than the high dose rates commonly used in the past in experimental investigations. In conclusion, I think it might be worth while to say a word about the genetic damage done by fallout from weapons tests or possible nuclear attacks upon the United States. I do not feel it advisable now to engage in the sort of “numbers game” that has been played in the past. It seems important to me to emphasize the vast range of uncertainty embodied in such estimates, an uncertainty extending over two orders of magnitude, or a hundredfold difference. Insofar as the effects being compared are produced by radiation at a low dose rate and are linearly proportional to dose, it is sufficient to keep in mind that the average accumulated fallout dose from weapons tests through 1959 to persons in the United States is estimated to be 0.15 roentgen, lifetime dose. (The new edition of “The Effects of Nuclear Weapons” states the dose as 0.1 rem.) From this figure, taking the higher one, resulting from some 92 megatonsof fission explosion, one can extrapolate to the fallout exposure for a similarly housed and unprotected population in the event of 1,500, 3,000, 10,000 megatons, or larger attacks or wars. Depending upon the assumptionsasto the relative proportionsoffission and fusion, one can calculate fallout doses to target nations rather inexactly and to nontarget nations more exactly. It is worth emphasizing that the calculated dose from stratospheric fallout to a nontarget nation located in the Northern Hemisphere in the zone of heaviest. deposition, between latitudes 30° and 60°, amounts to about 10 to 12 roentgens in the case of a 20,000-megaton war of which 50 to 60 percent mightbe fission. In other words, a nuclear war of such magnitude as to suffice to devastate the United States, the U.S.S.R., and all of Western Europe, would produce fallout that would only equal or slightly exceed in terms of its genetic LORSRSEBAeebeaFategereiseRe Coreinea