Kingdom (3). The soil levels of Zr°- Nb*, which are less affected by the 1957 and earlier fallout than are levels of the longer-lived nuclides, show a maximum variation of 20 percent from the New York City cumulative fallout levels. In addition, the results of sys- tematic ionization-chamber measurements of open-field dose rates performed by Vennart (3) in Belmont, Surrey, England, closely parallel the Zr“*-Nb™ dose rate curve of Fig. 3. These observations imply (i) that weathering and roughness of terrain had little effect on doses from fallout activities during the two-year period, and (ii) that the most significant contribution to total-radiation dose rates was made by radioactive zirconium, or possibly by other fission products of comparably short half-life. Although the beta emitters in faliout are not sufficiently energetic to cause significant external doses except through direct deposition on body surfaces, internal doses do occur through inhalation and ingestion of debris particles (5). In addition, the chemical similarity of some of the radionuclides to elements normally assimilated by the body results in concentrated doses to specific tissues. The over-all effect of radiation on the population cannot be known, therefore, until many complex meteorological, physica), chemical, and biological factors are thoroughly understood. It is clear, however, that any valid assessment of the effect of radiation, past or future, must include consideration of fallout and more realistic treatment of the short-lived fission products. Refereaces and Notes 1, “Radiological Health Data Reports,” U.S. Public Health Service Publs. Nos. PB I61371-1 throueh PB 161371-10 (1960-61). 2, “Strondum Program Quarterly Summary Reports,” U.S. Atomie Energy Comm. Publs. Nos. HASL-42, HASL-51, HASL4S, HASL- 77, HASL-84, HASL-9$ (1958-61). 3. D. H. Peirson and L. Salmon, Nature 164, 1678 (1959); J. Vennart, (bid. 188 722 W.F Libby, Proc. Vail. Acad. Sct. US. 48, YS9 (1959). G. A. Welford and W. R. Collins, Jr. Sct ence 131, 1710 61960), . G. A. Welford and J. H. Hartey, U.S. Atomic ne Comm. Publ. No. HASL-42 (1958), 4 & A. Welford, W. R, Collins, Se, R. S. Morse, D. C. Sutton, Talanra 5, 168 (1960); WwW. R. Collins, Jr, U.S. Atomic Energy Comm. Rept. No. HASL44 (1989); “Manual of Standard Procedures,” U.S, Atomic En- ergy Comm, Publ. No. NYO-4700 (1957). . R. L. Heath, U.S. Atomic Energy Comm. Rept. No. [DO-16408 (1957). . J, H. Harley and N. A. Hallden, Nucleonics 13, 32 (1955). . G, Friedlander and J. W. Kennedy, Nuclear and Radiochemistry (Wiley, New York, 195$). . N. A. Hailden and J. H. Hartey, US. Atoone Energy Comm. Rept. No. NYO-4859 (1957); J, H. Harley, N. A. Halden, L. D. ¥. Ong, U.S. Atomie Energy Comm. Rept. No. HASL93 (1960). » D. Strominger, J. M. Hollanser, G. T. Seaborg, Ress. Modern Phys. 3@, 2 (1958). . R. T. Graveson, U.S. Atomic Energy Comm. Rept. No. HASL-59 (1989), . AL A. Jarrett, Am. ind. Hyg. Assoc. Quart. 20, 299 (1959). . The thermonuclear data are taken from an unfinished report by John H. Harley and Naomi (1960). . P F. Guatatiog, Radiology 78, 282 (1960). . Report of the United Nations Scientific Comimuttee on the Effects of Atomic Radiation ratory). We gratefully acknowledge their coOperation and assistance in this and other phases of the study. We also acknowledge Hazards to Man of Nuclear and Allied Radiations: A Second Report to the Medical Research Council (Her Majesty's Stationery Oratory), who did much of the sample Preparation and analysis, and of Wayne M. we from similar latitudes in both the United States (/, 4) and the United (United Nations, New Office, Londoa, 1960). 6. E. A. Martell, Science York, 129, i958); 1197 The 11959); and P. J. Drevinsky, ibid. 132. 1523 (1960). 7. L. B. Lockhart, Je, R. A. Baus, R. L. Patterson, Jr., A. W. Saunders, Jr., idtd. 130, 161 ¢1959); L. B. Lockhart, Jr, R. L. Patter- son, Jr, A. W. Saunders, Jr., R. W. Black, thid, 133, 184 (1960). 57 A. Hailden (Health and Safety Labo- the assistance of Gustave Farnham and Salvatore Garafalo (Health and Safety LabLowder, who reviewed the discussion of kamma-ray doses and dose rates. . Climatological Data, Washington 9, Nos. 1-12 (1958); 10, Nos. t~12 (1959). 2. L. R. Solon, W. M. Lowder, A. V. Zila, H. D. LeVine, H. Blatz, M. Eisenbud, Science 127, 1183 (1958): L. R. Solon, W. M. Lowder, A. Shambon, H. Blatz, hid. t31. 903 (1960).