od arte ap apes * data, such as -4 Gurhips between T, and age, the Marshallese pec with a value of 70 days reported (5). The data of Miettinen suggest an sverage value of about 70 days for the ages 16 through 75 years. Lists of “age limits” indicate most of :- s@utthood is reached” (1). Other investigators age. Whether the inclusion of individuals of a age ACX, OF Speci -...’ pilahas said, “If there is a chanze of hal- dife‘with age then it presumably stamee at bith and imcreases steadily until indicate a stranger support for a relationship between T, and age. Bengtsson et al. state “Fn: results also confirm that biological half- these individuals were Jess than 50 years of ages down to 16 years has the effect of Jowering the average value of T, for these groups compared to data on groups of “adults” . #m.« for cesium increases with age” (12). , presented by Rundo and Hansen and others, is ‘Onstezd et al. report that in their studies in- (’ not known. Possibly other biological and ser children, perhaps by a factor of three 2 five.” The Federal Radiation Council, in its Report Wo. 7, <19) stated: “The data for persons younger than 25 years suggest that the biological] half-life becore maturity may be a function of age. Biological half-lives of about 20 days or tess have been reported for infants. For this report a value of 30 days is used as the biological half-life of cesium-187 in infants.” A value of 30 days for infants appears to be a conservative assumr‘ion since the available data for infants show values close to, but below, ‘thir value. ; Considering the available values of T, for the entire range of ages in the population, the trend that is suggested for T, and age may be presented graphically. The solid line in figure 2 is drawn to account for the apparent rapid change of T, with age for those less than about 25 years of age, to provide an average value of about 80 days for younger adults as suggested by Boni’s measurements, and to provide an average value for adults over 25 years of cage of about 100 days. Considering all age ‘groups, the solid line in figure 2 develops an average T, for all ages of about 75 days. 120—] Bete Approntngiion seeamieemmemnsan > 12.0617 6 omtpmimemce § <78) contains the following: “This value is almost certainly too large Model development t. Strontium-89, Strontium-90, and Cesium-137” environmental factors are more important. i voxing more than 6,000 individuals, our findings suggest that, within a single spc cies, biological half-life is dependent on age” (17). an referencing the use of 100 days for the ‘gkiogical half-life of cesium in man, the December 1964 report to the Federal Radiation asuncil by the National Academy of Sciences Advisory Committee, entitled “Implications to Maun of Irradiation by Internally Deposited OLOGICAL MALF-TIME (aay) ude GY Shete ate + hw * Guarded state ne is,by B( ) investigators - indicate reservcation: ’ “apecifying trends in the Boni's value of 81 days, which is applicable ior adults 2% to 40 years of age, is in close &greement with the average value of the lower SO nage ee MONREL ERE ENE Me mE Nec Ntewomgpnten ner Aimit for adults for all investigators of 78 days. However, there are little data for ages within the category specified as “adults” to determine if there is a trcnd of change in T, as a function of age above about 25 years. The average value © far adalts for all investigators, those that Specified a range of values and those that did “ao, is 101 days. The most data for an early saidy for all ages in a population group are for ~—_—_}—_4 " 4 i “ AGE tynen} +——2 Figure 2. Biological half-time versus age The three segments of figure 2 may be approximated by: where: Ty = 12.8 (x!+-e-*) (W) T= biological half jife (years) x=age (years) @ecember 1965 _ __ 422% ajo8| PODS