-12- the previously released data 2/ bf 5/ have failed to reveal any more serious deviation. To summarize, desert regions with little or no precipitation, or with only very minimum precipitation, apparently have minimum long-range, world-wide fallout, but other regions do not show that the fallout is proportional to the total precipitation, nor should it be expected to be so, but detailed conditions related to frequency of precipitation might well be important. The data to date do not reveal deviations from the general average . by more than about a factor of 2 and, in fact, they seem to indicate a smaller deviation than this. There is some evidence that certain areas have had more fallout than one might expect on the model described above and on previous occasions. In particular, there are reports that certain areas in England show higher levels, but the deviations appear to be considerably less than two-fold. mo More important, probably, than the variations in total fallout due to weather conditions is the effect of calcium in the soil in reducing the rate of assimilation of radioactive strontium by plants. The plants assimilate strontium because it is chemically similar to calcium and, since their appetite for calcium is limited, a larger calcium content in the. soil dilutes the strontium so that a smaller fraction is assimilated. This effect might amount to a factor of five in the human body assimilation of radio-~ strontium in regions with very low calcium content in the top soil. 2/ "Radioactive Strontium Fallout," W. F. Libby, Proc. L/ "Summary of Analytical Results from the HASL Strontium Program to June 1956," John H. Harley, Edward P. Hardy, Jr., George A. Welford, Ira B. Whitney, and Merril Eisenbud, NYO0-4751, August 31, 1956. 5/ Project Sunshine Bulletins Nos. it and 12, The Enrico Fermi Institute for Nuclear Studies, The University of Chicago, Dec. 1, 1955 and Aug. 1, 1956. (more)