CESIUM 233 



Cesium 134 (2.3 yr) Beta 0.090, 0.658 Gamma 0.568- 1.3 5 



Cat. No. Sp. Act. Form Co.st ('hem. (hmt. Jiadiochem. Cont. 



Cs-134-I 60mc/g CssCO^ $34/mc — — 



Cs-134-P l-3mc/inf!; CsCl $l/mc — — 



Mica W. Int.C. Scint. C. Rf/mc 50% Self-ab.s. 



2 X 10-4 17 X 10-4 9.8 X lO-" 9 55 (detn.) 



Cesium 137 (33 yr) Beta 1.2, 0.51 Gamma 



Barium 137"' (2.(1 min) Beta Gamma 0.602 77' 



Cat. No. Sp. Act. Form Cost Chem. Cont. Radiochem. Cont. 



CsBa-137-P CF CsCl $2/mc — Bai^'"' daughter (2.0 min) 



Mica W. Int. C. Scint. C. 50 % Self-ahs. 



7 X 10-* 7 X 10-« 1.4 X 10-3 50 (detn.) 



Critical Org. Bodij Air Water Effect. Ty^ 



Muscle 90 mc 2 X 10-^ 1.5 X 10-' 17 days 



Intake Levels. Cesium occurs in traces in plants, animals, and soils 

 and, as one of the alkali metals, is expected to behave similarly to sodium 

 and potassium, although it is not considered an essential element. It 

 occurs in the earth's crust at about 7 ppm and in sea water at about 

 0.002 ppm. The acute toxicity for various cesium compounds admin- 

 istered intraperitoneally to rats was found to be relatively low, the LD.^o 

 being about 700 to 1100 mg/kg of cesium except for the hydroxide, which 

 had a value of 89 mg/kg presumably because of the pH (Cs-1). Cesium 

 has been of biological importance primarily because Cs^^^ is a long-lived 

 fission product and is also potentially useful as a radiation source. 



Radioassay. Preparation Cs-134-P will probably be the one of choice, 

 provided the specific activity is not too low. Cs^^^-Ba^*^'" offers a much 

 higher specific activity but has a long half-life, w^hich may be a disadvan- 

 tage in some situations. Routine beta or gamma counting is satisfactory 

 for both preparations, although the latter is preferred in order to elim- 

 inate self-absorption problems. The Ba^"'" daughter presents no prob- 

 lems, because equilibrium conditions are attained after the samples have 

 been allowed to stand for about 30 min. 



Chemistry. Convenient methods for estimation of cesium in biological 

 materials are not available. It was found that cesium tended to be 

 adsorbed into the glaze of porcelain ware during dry-ashing, and therefore 

 the procedure should be employed with caution. No losses have been 

 noted with routine wet-ashing. 



Typical Methods. In metabolism studies, Cs^^^ was administered at 

 about pH 7 at the following levels: rats, 40 /xc; cattle, sheep, and swine, 

 1.7 to 2.5 mc/100 lb body weight; poultry, 360 /xc/lb body weight (Cs-2, 

 Cs-3). Samples were usually digested in concentrated HNO3, and ali- 



