i, considered either to be essentially instantaneous, or received at a constant dose rate over a period of minutes. From previous animal Y. 4 hL werden away experimentation it might be expected that the dose received by ex- posed individuals in the present study, extending over two or three days, would produce less of an effect than would the same total dose given over a few minutes. It is not possible without further expertmentation to attempt quantification of the degree to which observed :, ‘hip, effects in the population studies may have been altered by this particular combination of dose rate and time during which the total dose was delivered. . e ismonyege Hematological findings were somewhat similar to those seen following single doses of penetrating radiation in animals. However, the time course of changes in both the leukocyte and platelet counts in the Rongelap group was markedly different from that seen in animals. &“eh Maximum depression of these elements occurred much later in these in- =. dividuals than is seen in animals, and the trend toward normal was considerably delayed. The marked delay in return to normal leémkocyte € z. ~ .- values in the present study appears to exceed that observed in’ the Hiroshima and Nagasaki casualties. Further evidence that the return to normal may be later in human beings than in animals can be seen in the response of the few cases of the Argonne and Los Alamos accidents. Although the doses, types, and conditions of irradiations were sufficiently different in the several series of exposed human beings to preclude strict comparisons among them, the added evidence from the present studies would seem to validate the general conclusions that the time pattern or hematological changes following irradiation in man is significantly different from that observed in the large species of animals studied to date. 2.3.5 Program 6, Service Equipment and Techniques Program 6 included six projects concerned with the developing, testing, and analysing of various aspects of weapons effects on service equipment and operational techniques. Project 6.1 was successful in obtaining excellent radarscope LeteeGaile pk photos of the detonation and blast phenomena for utilization in establishing Indirect Bomb Damage Assessment (IBDA) procedures for high yield weapons. The high-yield weapons detonated in regions such as Bikini, where sharp land and water contrasts are obtainable, gave excellent results for radar return studies and air crew training for the 20 Strategic Air Command (SAC) air crews who participated. Copled/OOE LANL, J-Div, 4O ’