strontium ispresent in, less than Tneoretical, amounts,vibnemaoors ranging from one to ten percent, This is thought to be true also of other fission products having gaseous precursors. The suggestion is thus raised that the rate of dissolution of the particles in the soil is a factor which should be taken into account. It was pointed out by the Tracerlab investigators that enough debris material is on hand to make experiments on the dissolution and plant uptake using the actual material rather than the corresponding soluble salts. Detectable amounts of strontium in the bones of animals picked up on the Alamagordo site have been reported . The health physics problem, that is the toxicity of ingested strontium requires a relatively smail revision. It appears that the toxicity of radium as estimated from Silberstein's data on radium poisoning is slightly in error. This error has resulted from the assumption that all of the poisoning was due to radium, whereas it has since been discovered that a large fraction of the poisoning was caused by meso-thorium. According to Marignelli radium is possibly only 1/4 the toxecity of meso-thorium so that m the radium mid-lethal doses should be increased by a factor of from two to 4yy oe four. Since the toxicity of strontium 90 was based on the experimental Re yw comparison of the toxicity of strontium 89 with radium in rats and on the absolute toxécity of radium calculated from Silberstein's data the estimated tox@city of strontium 90 must also be increased by a factor of from two to four. In spite of this kind of uncertainty the toxicity of strontium 90 is one of the most certain factors in the entire analysis. Dispersion Density The data of three groups F9,o-is presented in such a manner that absolute estimates of dispersion density may be estimated. are the BNL, KAPL and NRL. OFsnt-c-4737, These groups The cloud from the Ranger Able shot fired at "OBSERVATIONS ON FALL OUT FROM THE NEVADA TESTS, JANUARY 27 THRU FEBRUARY 6, 1951," Weiss and Kuper. ? KAPL-559, EVALUATION OF THE EFFECTS OF ATOMIC BOMB DETONATIONS IN THE STATE OF NEVADA ON AIRBORN CONTAMINATION AT KAPL, KNOLLS SITE AND ENVIRONS", Cherubum et al., 7 May 1951. T wWRL-3866RD-57, “REPORT ON COLLECTIONS OF RADIO-ACTIVITY FROM THE RANGER A-BOMB TESTS", Keene et al., 1 August 1951. + UCLA-111, "SUMMARY OF THE RADIOLOGICAL FINDINGS IN ANIMALS FROM THE BIOLOGICAL SURVEYS OF 1947, 1948, 1949 and 1950; J. T. Leitch, 12 February 1951. WE MoICIS OG Feroey ofte l, Kartuye Daahring Ln the Trt, aud Mehabrabie, f Rtrortah Kadunin "26 Yotay regs, SLbsrAe, , DO® ARCHIVES