CENERAL CONCLUSIONS We believe our most Significant findings ares 1. Ths dependence of radiostrontium uptake on soil calcium. ¢. The remarkable uniformity in the radiostrontium activity in Jootogion 3, Our inability to account for the bulk of the debris from Ivy. 4, The absence of gross fractionation of either $r99 or Sr90 in materials when the concentration is expressed as d/min/gm Ca, analyzed, The data provide a tentative measure of the significance of Sr70 nuclear detonations to date. What would we find a few years hence there were no intervening detonations? Milk being the principal if Bourca of human Ca, we have estimated the rate at which Sr90 would be debleted from soil, assuming the availability remains as it is. Appendix discusses half life from soil can vary widely in pastures that feed milk cops: 1.5 to 4.5 years for fields from which cowpeas are cropped continuously to cows that feed elsewhere, and 170 years for pastures in which feed, The bulk of the Sr70 in Case I is transferred to fields ma the cows cows fed by cowpeas grown elsewhers. Hare is an axample of one p of the many that make it difficult to ganeraliza about the data wq@ have obtained. 6 d/m/gm Ca is a representative figure for 5r89-50 of which about 1.5 d/m is Sr7¥, This compares with 870 d/m/gm Ca at tolerance (1 pe in 47 Ke skeleton containing 36% Ca). The ratio of the obsarved activity tb the tolerance activity is thus approximately... Potential deposition of material now stored in the atmosphere onglYy easily Thus, we can tentatively conclude that if the Sr™ double this fig in soil is not with the soil (as seems to be the case}, a skeleton which begins +@ at this time would be expected to contain _l epleted develop of the tolerance burden. This burden will diminish slowly with radioact isWdecay but can be markedly reduced by a shift in the equilibrium between soil and biological falcium