. during purification (10). Indeed, the low RNA/DNA ratio (1:3) reported by Smith and Stoker (//) for Coxiella burnettt may reflect such losses and suggests . the physicochemicallability of rickettsial RNA. The differences between the results obtained at 36°C and at 4°C suggest the participation of enzymatic processes in the loss of nucleic acids from the rickettsiae. Since the omission of glutamic acid did not influence the experimental results, “energy metabolism” does not seem to be of importance. The present findings are perhaps analogous to the degradation of RNA in resting cultures of Escherichia coli H, which has been reported by Stephenson and Moyle (7/2). The foss of nucleic acids from R. moosert upon incubation at 36°C may be one of the reasons for the concomitant inactivation of the biological properties of this organism. Z. A. Coun, F, E. Haun, W. Cectowskl, F. M. BozEMAn Department of Rickettsial Diseases, Walter Reed Army Institute of Research, Washington, D.C. References M. R. Bovarnick and E. G. Allen, J. Bac- teriol. 73, 56 (1957). » J. Gen. Physiol. 38, 169 (1954). Np C, L. Wisseman et al., J. Immunol, 67, 123 (1951). R. B. Roberts et al., Carnegie Inst. Wash. Publ. 607 (1955). SN wre 1. CG. H. Fiske and Y. Subbarow, ibid. 66, 375 {1925). W. J. Mejbaum, Z. physiol. Chem. Hoppe- Chem, 161, 83 (1954). Seyler’s 258, 117 (1939), G. Cerriotti, J. Biol. Chem. 198, 297 (1952). E. Chargaff and J. N. Davidson, The Nucleic Acids (Academic Press, New York, 1955), vol. II, chap, 16. 10. H. Ris and J. P. Fox, J. Exptl. Med, 89, 681 (1949). 11. J. B. Smith and M. G. P. Stoker, Brit. J. Expil. Pathol. 32, 433 (1951). 12. M. Stephenson and J. M. Moyle, Biochem. J. 45, vii (1949). eo . . G. Schmidt and §. J. Thannhauser, J. Biol. 4 October 1957 / f Barium-140 Radioactivity \ in Foods We wish to report the presence of the fission products barium-!40 and lanthanum-140 in certain foodstuffs in the United States during periods of nuclear weapons tests. The presence of these nuclides in the amounts observed in no way constitutes a hazard; it carries none of the potential implications associated, for example, with strontium-90. It is of practical concern primarily to those engaged in measurements of radioactivity near the natural levels, and when an ac- curate summation of total radiation is desired. As in the case of cesium-137 ({}, measurements of barium-140/lanthanum-140 may also be of value in the study of the fallout process. 7 FEBRUARY 1958 Barium-140 has a halflife of 12.8 days, and its daughter laathanum-140 has a half-life of 40.2 hours. Because of their somewhat similar biochemistry and the short half-life of lanthanum, secular equilibrium is likely to be maintained in biological systems, and both nuclides will follow the chemistry of barium. The biochemical behavior of barium-140 is similar to that of calcium and of strontium-90, but the short halflife of barium-140 and the larger biological discrimination factors against it render it potentially much Jess dangerous than strontium-90. The presence of barium-140 was first noted in some deer in New Mexico dur- 407938 SOT TTT OTT x“ 20- J = * NEW ORLEANS, LA. “| 4 BISMARK,N.D. uJ A oO lO x 4 4 wif 4 5 04;- = g © as 4 ~ ao 7 a2k | E ott , lo 20 10 MAY 20 JUNE 1 20 !o JULY 20 AUG I957 ing the summerof 1956—presumably the Fig. 1. Typical curves of upper channel activity versus date, for Bismarck, N.D., and New Orleans, La. large 4x liquid scintillation counter designed especially for the measurement of radioactivity at natural levels in people channel occurred at other sampling points during the summer months, at none of them did the increase reach this level. Thirty-seven points are routinely sampled. The dates reported in Table 1 are those on which the samples (50 to 100 pounds of nonfat-dry milk solids) were result of the United States nuclear test Operation Redwing. It was detected and identified (by its haif-life} by means of the Los Alamos human counter (2), a and foodstuffs. A threefold increase was noted in the gammaactivityin the spec- tral region from 1! to 2 Mev (normally potassium-40 only). This corresponds roughly to a barium-140 activity of 0.03 wc per 70 kg, which is 6 percent of the received at Los Alamos. In general, the on the basis of the “large population” value (3). A cow taken directly from the New Mexico range showed a similar tion with meteorological data, the actual beef did not, perhaps because of different feeding habits or because of the time lag between slaughtering and the ap- Table 1. Barium-140 peak levels in milk. maximum permissible amount for man, amount of barium-140, bat commercial pearance of the meat on the retail market. While the apparent potassium-40 activity of milk samples showed a few instances of slight increases during 1956, it was not possible to identify the excess activity. Barium-140 appearedin several United States milk samples during the months of June, July, and August, 1957, pre- sumably as a result of distant fallout from the test operation in Nevada, Operation Plumb-bob, and perhaps from test operations of the U.S.S.R. Identification of the excess activity in the potassium region of the spectrum was again possible on the basis of the measured halflife. Confirmation of the assignment of the activity to barium-140 was obtained by spectral analysis, for which an 8- by 4-inch sodium iodide crystal in a steel room similar to the installation devel- oped by Marinelli and his coworkers at the Argonne National Laboratory (¢} was used. All five of the prominent barium-140/lanthanum-i40 gamma peaks were identified. Table { summarizes dates and concentrations of barium-140 in powdered milk for those locations at which the barium140 gamma activity exceeded that of natural potassium-40. While detectable increases in activity in the upper energy ae vn }~ = 08 delay between production andarrival is about 1 week, and for accurate correla- production date must be ascertained, Estimated Date received (1957) barium-140 content (myuc/lit of whole milk) Bismarck, ND. 7 Aug. 2.2 20 Aug. 0.85 Idaho Falis, Idaho 10 June 0.40 9 Aug. 0.46 5 Aug. 0.32 26 Aug. 0,54 Payette, Idaho 19 June 0.12 Louisville, Ky. 21 July 0.27 9 Aug. 0.46 New Orleans, La. 15 July 0.36 20 Aug. 0.19 Willows, Calif. 10 June 0.31 Ladysmith, Wis. 16 Aug. 0.23 Des Moines, Iowa 9 Aug. 0.18 Ogden, Utah 19 June 0,06 af 14 Aug. O15 are : Monroe, Utah o ete 11 June 25 July 0.09: 0.12 283 a