h.3r r in 30 years from natural background exposure and they recommend LOr as the top figure for average exposure of the population as a whole before age 30. As to the hazard from stromtium?9 the report states "if the concentration in human bones showed signs of rising greatly beyond one-hundredth of that corresponding to the maximumpermissible occupational level" they would feel that immediate consideration were required, This figure is 10 times the highest they report in man today. The National Academy of Sciences report states "It appears, then, that strontium?0 is not a current threat, but if there were any substantial increase in) the rate of contamination of the atmos- phere, it could become one.® The conclusions are to all intents and purposes identical to those of the National Academy of Sciences report. 1, Adequate justification should be required for the employment of 2. Dose levels to the individual -- 0.3r per week -- 200 r ina lifetime for occupational exposw’es and no mre than 50r the first thirty years of life. 3. No more than twice natural gackground from man-made sources for the population as a whole. NAS h. The present and foreseeable hazacds from external radiation due to fallout at present rate of testing is insignificant. As to internal hazards from strontium’? at its present level no detectable increase in the incidence of ill-effects is to be expected. "Nevertheless, recognizing all “ae inadequacy of our present any source of ionizing radiatior. on however small a scale. This is not explicitly stated in the National Academy of Sciermes report but is inherent in it. knowledge, we cannot ignore the possibility, that if the rate of firing increases and particu’arly if greater numbers af thermo- muclear weapons are used, we ccild within the lifetime of some now living, be approaching leve.s at which il] effects might be produced in a small nusber of the population." This is a rather roundabout way of siying, "let's be careful." 5. a. All sources of radiation stould be under close inspection, A personal record not only of coses of radiation received during occupation but also of exposur' s from 411 other sources such as medical diagnostic radiology s.ould be kept for all persons .whose occupation exposes them :;o additional sources of radiation, The National Academy of Sciem2s report would seem to include the whole population in its sinilar recommendations. = - COLLECTIONS. REPRODUCL) FFrom THE OF THE ARO TS OF THE OF SCIENCES NATIONAL ac=ADEN - ( \