2 Table 3. Strontium-90 in milk from various locations, 1956-57. The numbers in parentheses in column 3 give the numberof samples. Location New Jersey (Bergen County) New Jersey (other} New York City (retail) * New York State (Perry) * MohawkValley North Carolina North Dakota (powdered) * Mississippi (State College, powdered }* Missouri (St. Louis, powdered ) * Oregon (Portland, powdered} * Virginia (Rockingham County ) Wisconsin (Columbus, powdered ) * Av.for all 1957 milk Date SU 9-10/57 Rangé 3.0-7.7 Av. 3.5 (14) Av. 5.5 (4) 10/57 9-10/57 8/57 5.5 Av. Av. ?/56 10/57 Ay. 4.5 6.6 (4) 5.3 (4) 10.0 6.5 6.5 7.0 3.8 (4) 5.5 6.1 * Estimated from an analysis reported by Health and Safety Laboratory, New York Operations Office of the AEC (4), extrapolated to late 1957. drinking water appears to be negligible. If rain water were consumed, this source would still only account for about 20 percent of the daily Sr®° intake. It is concluded that the Sr®° content in the diet of an average U.S. citizen in 1957 was about 6.5 SU, corresponding to an equilibrium base level of 1.6 SU, since the discrimination factor between diet and base appears to be about 4 (7, 5). If the diet concentration remains constant for a decade, the equilibrium bone level of 1.6 SU would be approached by young children. New-born children would have about half of this value on account of fetal discrimination, and adults would reach only 20 to 30 percent of the equilibrium level, because of the slow rate of exchange of the calcium in bone. J. Laurence Kup Rreta SLAKTER Lamont Geological Observatory, Columbia University, Palisades, New York References and Notes 1. W. R. Eckelmann, J. L. Kulp, A, R. Schulert, 2. Science 127, 219 (1958). Lamont Geological Observatory Contribution No. 302. This work was supported by the Riology and Medicine Division, U.S. Atomic Energy Commission. We acknowledge the valuable suggestions of W. R. Eckelmann, A. R. Schulert, E. Hodges, and E. Peets. R. Woehr assisted in the chemical operations, 3. H. L. Volchok et af., Ann, N.Y. Acad. Set. 71, 293 (1957); H. L, Volchok and J, L. Kuip, 4. Nucleonies 13, No. 8., 49 (1955). M. Eisenbud, Hearings of the Joint Committee on Atomic Energy, May 27-June 3, 1957 (GPO, Washington, D.C.), pp. 554, 591, 5. R. J. Bryant, ef al., HP/R 2353, {Atomic Energy Research Establishment, Harwell, Eng- 6. 7. land, 1956). United Nations Yearbook of Food and Agriculturaj Statistics, vol. 9, pt. 1 (1955). U.S. Dept. Agr, Handbook Ne. 62 (1957). 17 February 1958

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