over a long period of time were recommended. Based on these recommendations and those forthcoming from the International Commission on Rudiation Protection, the AEC may consider placing an upper limit of yearly exposure for atomic energy workers. However, the average exposure to atomic energy workers during Past operations has been so far below the maximum permissible level that the placing of a yearly upper limit would not be expected to impose any major restriction, The NAS report recommended an upper limit of 50 roentgens for individual exposure up to age 30, and 10r during the like period for the general populace. Except in the case of the March 1, 1954 incident involving intensive fallout in the Marshall Island area, no individual outside the testing areas has been exposed to even the 10r maximum recommended for the populace as a result of fallout from the U.S. nuclear testing program. The NAS report estimates that if the nuclear weapons tests were continued at the present rate the average exposure for the general population of the United States over a 30-year period would be about one-tenth of a roentgen. In summary, the report was reassuring as regards nuclear weapons testing; it did not attempt to face up to the problems of an atomic war; and, finally, it was preoccupied with the potential hazards inherent in a developing era of large scale atomic power. As to the Strontium-90 accumulating in the biosphere, the AEC will continue its extensive program of maintaining col~ lections stations throughout the world and of analyses of the samples. This close and continuing checking system will provide ample warning of any significant upward trends in the Strontium90 content of the biosphere before hazardous levels would be approached, It is indicated in the NAS report that the highest levels observed throughout the world are about 1/100 of the Academy's most conservative estimate of permissible concentration for the population as a whole. Furthermore, our knowledge of present pollution from radiostrontium is more exact and more extensive than that with respect to any other atmospheric pollution. The attached summaries of Professor Muller's article and of the Norwegian matter are self-explanatory. Sincerely yours, /s/ Lewis L. Strauss Chairman Enclosures: 1,2 and 4 (Unclassified) 3 (Secret - ) Honorable Harold E. Stassen Special Assistant to the President