| . go Table 1. Cestum-137 half-time \) trom the Meratare 105 -aeatte 782 Be. 36-75 -) tate 0-14 a nae 7 6 4 7-76 “ . ~35 Marshallese people 30 ‘eorma) scbjects *@ ‘ adult 1 i adult adult 100 8 mes average value average velue 2 ° 83 56 . : “ ¥ «ete : °110 . : . +56 298 #170 997 . “71 °©%6 3 90 i 81 3 9 oman 18 { v2 # days i snfant - early infancy 12 Lenfant Tcnfpne 2 slant B infant * ebad | ” Ls eta, ¥ 7 he tat ” adult > erult * eduit pi ‘art 2 eauit bedult : 33 ' 35 badah t adult - adult 3 edul: Z adietr ee z 40 as ota 1 ot , 33 108 100 : 1 #4 : 49 53 : « @iderly men 76-126 * “T ) oy Oo e) °) *) @) ty ) ba) a4 ts) m) ts ") 3) +5 qe 43 — $3 £18 ae _ Ad _ _ ts as (ity 4s) _ 8 _ Sy _ ts 38 18 16 101 121 - se) ae a 94 108 - — a4 136 73 _ __ sr ait 101 #3.3) 2.2) seo " f ts is ae ts) a8 6) _ +2.0 (ts) bed +1.4 216 ti) bad 0 vl ae ntertai..ty in the measurement is given, when available, where dats .-. presentes for one subject. » Sinall fraction climinated sh e fraction eliminated iv tadion: tvily measurement “sotion ot dretary analysia <% 1 saonths ‘ater one 1 NENSOR eCepeROM ge + 5p! Fomponent ~ Sle: component F.4m table 1 and from figure 1, it is seen that much of the data on T, are for “adults”, 712 ae own ad. “5 i 4 T= _~ eet ~~ 0 tae §S SOND: OA dagle sxmgie hae duty prorentatton Me, | on Avernge voles bat 0 range of ayon. ts Figure 1. Biological half-time versus age ) ¢) 0) 0) ° A i if ® _ _ 131] _ 32 . : elderly women 200 53-140 7 _- 1 35 ’ 33 2t 18 42 43 * w% ~80 86-312 +3 — 2 fh eu 3 aut 5 ms cathe rt . ~ 25 9.6) 13 ; “4 days 36 days a6 days 43 days 88-120 ~ 92-187 - sto #3 91 .7 days 54-114 0-1 % 32 6.6] aduite 3 sefont ) @) ) e) — 23 tinantof EB ft days 1 infant ? warty infancy 37. 310-147 = 109-148 of ~ geen| i ox Mes ; } ? ) ®) » j “ 8 _ -_ -_ 310-119 95 60 643% 3 ween 2 «.man-ER iasiant of 18 ae vic No 140 41210 4315 @75 &. | ) ? +89 ©145 ©3125 0188 - winter _ -~ 04 136 4309 7” jo . § if } : £ 3 = {fie guremer soo-tes am 414s i‘ ) “9 ‘ : x: +10 _ 0.8-1, 8-1.38 400 135 4150 4322 be + ) 410 70 os Ga 1959) Ge 1961) adults adults 1 : _ — 14,the vatoe — ) ® $5.8} 2:10 -dulta, )-40 4 chicdren a _ odteviation + , Reeme 2cae lke & $4. wt ome 50 oiages _- € at Sl. ee Fo 39 a ' sr é e Range (days)* /Refer- ‘h 8 gis! “A siv. + git.“ Te (days) L Age (years) ¥F- Group Lo tem: om ot eee PHT eaeSOF ORF re Sengesaenmet ey ot gee nets Sa OY pee. sp > =s2> SS .Faa. ee Saieheenemmninnodea oT vty igen RR & and that investigators have reported halftimes, for adult groups, of about one day for a small fraction of the cesium--137 intake (about 10 percent) and values between about 60 ans 180 days for the major portion of the intay While part of the difference in yalues from various investigators may lie in the realm of factors of instrumentation, calibration, laboratory technique, etc., the measured values generally appear to represent real difference: among individuals. The range of values obtained by a single investigator for a ero: of subjects must involve many biological and. environmental factors for which there is litt information. No attempt will be made t- identify these factors except for the possible influence of age on the biological half-time of _ cesium-187 in man (age may be an indirect factor). The data are meager, but figure 1 suggest. "that the value of T, for those groups und about 20 to 25 years of age decreases with 1: _and that T, may be as low as 6 to 7 da: for infants a few daysold. For the four infan'in figure 1, the average value is about 15 day: which agrees with Pendleton’s average of 1° days for five infants. One additional feaiure in the data is po.sib) ° significant. For the age groups reported, | investigator (from the available reports) hv — reported a value of T, greater than 70 days‘ groups under 25 years of age or a valuc than about 50 to 60 days for groups aver years of age. Radiolog;cal Health 4 f Rh.