This does leave the question of genetic effects, which may exist down to any dose level. Past tests have increased temporarily the natural back- ground of penetrating radiation by a few percent, which may have produced ealculable but not observable genetic effects. For the foreseeable atmospheric shots it would appear that the total expected fallout would be smaller than for the U.S. HARDTACK series of 1958. In summary, optimum progress in weapon and device development and in obtaining effects information, would involve a diversified test capability, underground, atmospheric, underwater, and ultimately exoatmospheric. In addition to minimizing problems of contamination, underground testing has advantages in certain cases; for example, to deny intelligence information to the enemy, for diagnostics in specific instances, and for relative freedom from weather delays. Atmospheric tests are essential for large yield tests, for most effects determinations, particularly in regard to nuclear weapons on nuclear weapons and on equipment. Determination of effects against underground installations should be possible largely through underground tests. It must be recognized, however, that even those tests which can be done underground can in many instances be done much faster and less expensively in the atmosphere. Accordingly, in the event that large fission yield weapons are authorized in the atmosphere, small weapon tests not requiring heavy instrumentation might just as well be conducted on balloons ig,the interest ‘‘ of speed since they will contribute little additional activity to worldwide | fallout. ve 4 The above considerations lead to the need to take immediate steps to ready ourselves for the whole spectrum of tests even though the actual decision ys OF to test other than underground may be made later and be based on 3hthan

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