ray 7 We conclude that the average Cs‘*”? body burdens have remained essentially constant since.the spring of 1956. The increase of LS’s burden, for example, is offset by a decrease in subject. can be ascribed to dietary fluctuations. » burden. These change The estimate of radioactive contamination of the human body under continual intake of radioactive foods and water would be greatly aided by tk establishment of a significant parameter describing the radioactivity of bot Thus, in the last few years, great efforts have been expended in establishir whether the Sr”/Ca ratio in the diet leads to a reliable evaluation of Sr i in the human skeleton. Our first efforts along these lines concerning Cs’? led to the speculation as to whether the Csi37/K in the diet could be regard. as a reliable parameter for the estimate of Cs!*? body burden. Contrasted the findings with the Sr*®/Ca, the Cs*7/K in the body was found to be 2.2 ti: the ratio in the urine of a single individual. (ANL-5679, p. 29-30, JuneDecember 1956}. Taking advantage of the constancy of Cs'*? burden experienced in th last year, the excreta of two of the control subjects ( | and ___) were collected for several days and analyzed for Cs'®’ and K. The pertinent dat» obtained are shown in Table 6. 1 ra TABLE 6 subject > < ~ g K/day in urine g K/day in feces oe ££= = = CS s : S 2.53 .65 = 2.0 uc Cs'3’/day in urine 33.5 40 duc Csi3 /g K in urine 13.2 20 Cs/K in body*: ratio pees Cs/K in urine 2.6 4 1.9 *This ratio has been called assimilation ratio in the body’‘of the paper. . ‘oe & An assimilation ratio of 1.9 was found for subject_____ and 2.6 for subject =. The average value is 2.2 which is in agreement with the bei Zils previously“reported value for RER. Owing to the low radioactivities due to K* and Cs!3" in the feces of these subjects and the relatively high content of Ra@& therein, due to natural intake, it has not been possible to de- termine the fecal Cs'*7/K by simple gammaray analysis alone. Efforts to measure this ratio are currently under way, Additional pertinent infor mation is given later in the body of this report, concerning studies on . Marshallese subjects of relatively high Cs 37 content, who, however, coulc not be considered in equilibrium with their environment at the time of measurement. “BE ee er Ciret ge ede io Peed . Dn, .+e PRIVACY ACT MATERIAL REMOVED . eo i