\ | As a result, the Sr/Ca ratio in the Fetus and newoorn is approximately 1/8 to 1/10 that of the adult, and the resulting dose to the fetus is less than that to adults. The dose to a young infant being breast fed will of course also be less than that calculated for adults. The OR body /diet Tor young infants is 0.9;2?4 that is, the young infant nearly equilibrates with his diet. However, the mothers’ milk, as discussed previously, has a Sr/Ca ratio ~ 0.1 that of the adult diet. The OR body/diet + en decreases to 0.5 for a l-year-old and by arproximately 30r4 years of age has reached the adult 2 value of 0.25, 77498 ’ 3 Similar data are available for 3To5, Cesium-1327 is metabolized and turned over more rapidly in presnant women than in nonpre: AS a result, isin. oe Cs incorroration in 5 are less than would be expected from adults. . was the fetus and the resulting exposure normal retention tires cbserved for mExtrerimental data further indicate that fcr the fetus and for breast-fed infants the cconcentraticn of Cs and the resulting dose never exceeds that of the mother or of other adults. . 9 -. in reports by Runco,” Linume et 3 = calculated > for an adult for 1 al., LO A . il 5 and Cook and Snyder, the dese 5 * . Cs is a conservative estimate for +the Pat fetus and the newborn. 3. Dose to Children Relative to Adults 137 Cs — A considerable body of evidence is available which indicates that the half-time for 137 Cs in the body is a function of age, with a more . 11-14 rapid turnover for younger ages. . . . The biological half-time appears to