-12- effects, if test fallout does so. An examination of -ital records should be made to test for such effects and tre Atomic Energy Commission is doing so as best it can. The United Nations Scientific Committee on the Effects of Atomic Radiation has been comparing the data on natural background dosages, and it is hoped that this study will be continued and that the search will be made for observable effects of variations in the natural background dosege, for it is certain that any effects due to gamma rays from fallout must be already present in much larger measure due to the natural dosage. TI, VARIATION IN INDIVIDUAL STRONTIUM-90 BURDENS What is the likelihood that even though the average strontium-90 content be well within tolerance limits, that a- few individuals should exceed tolerance limits? Let us con- sider first the case which will ultimately hold, the situation of complete equilibrium with the environment in so far as the strontium-90 burden is concerned. The only way we can make judgments about the expected individual varistions from the mean concentration is by direct experiment on human body composition, not only for strontium-90 but for other analogous constituents. Most of the recent data on the strontium-90 body burden are from odd bits of bone removed during surgical operations, but fortunately we have actual data for the strontium-90 content of the entire bodies of some several dozen stillborn childrenl/in the city of Chicago in the year 1953. A strenuous effort is now being made on the Sunshine Project to continue this series and 1. W. F. Libby, "Radioactive Strontium Fallout," Proc. Nat. Acad. Sci. 42, No. 6, 365-390 (1956); University of =e B&B B&B & 1] B&B BB km & BD ee Re OR ek. ei Chicago, Project Sunshine Bulietin No. 12, August l, 1956.

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