2 figure is in good agreement with the geochemical value of 15 + 2. If strontium-90 becomes uniformly mixed with the soil, as may occur in tilled fields, this factor will permit prediction of human bone level directly from soil analyses. Therelatively uniform distribution of common strontium in human bone refiects the uniformity in human diet. This observation means that variations in strontium/calcium ratios in different areas will not be an important factor in the distribution of strontium-90 from 0 40 AO PPM 120 160 200 240 280 320 360 400 STRONTIUM Fig. 1. Histogram of common strontium in ash of whole skeleton from New York City. vegetables, the predicted over-all discrimination factor would be 16. This nuclear tests in the world’s population. D. L. Tourser, Jf. L. Kuve E. Hopcrs, P. W. Gast J. M. Wamp er Lamont Geological Observatory, Columbia University, Palisades, New York References and Notes 1, W. R. Eckelmann, J. L. Kulp, A. R. Schulert, Science 127, 266 (1958). K. K, Turekian and J. L. Kulp, Science 124, 405 (1956). R. M. Hodges et al., J. Biel. Chem. 185, 518 (1950). Lamont Geological Observatory contribution No. 304, This research was carried out under contract AT(30-1)-1656 between the US. Atomic Energy Commission and Columbia University. The criticsms and suggestions of Dr. K. K. Turekian ae appreciated. We acknowledge the assistanie of Mr. P. Hazlett. . A paper describing th: details of this work is being prepared by A. %. Schulert, J. L. Kulp and E. Hodges. E. M. Sowden and 5 R. Stitch, Biockem, J. 67, 104 (1957). C. L. Comar et al., Proce. Soc. Exptl, Biol. Med, 48, 232 (1955). K. K. Turekian and . L. Kulp, Geechim. et Cosmochim. Acta 10, '45 (1956). R. Menzel, private coamunication. W. J. Visek ef al, jf. Dairy Sci. 35, 783 (1952). 19 February 1958