I'UOMETHIUM 287 



Intake Levels. Pm^^' (element 61) was discovered during studies of 

 the rare-earth activities produced by uranium fission and was shown to be 

 a member of the lanthanum group of rare earths (Pm-1). Biological 

 interest has centered about its behavior in the animal and its property of 

 accumulation in bone and liver. 



Radioassay. Preparation Pm-147-P appears to offer advantages of 

 both low cost and freedom from radiocontamination. On account of the 

 soft-beta energy, which is about that of Ca^^, self-absorption considera- 

 tions will be quite important in the counting of samples. 



Chemistry. Presumably, routine wet- and dry-ashing methods can be 

 employed with biological samples. Methods for chemical estimation are 

 not available. However, ion-exchange resins have been employed most 

 effectively in the separation and identification of the radioisotope. 



Typical Methods. Although few details of methods are given, reference 

 (Pm-2) presents results of the distribution in rats of Pm^*^ as well as other 

 fission products. 



Pm-1. Coryell, Charles D., and Nathan Sugarman: "Radiochemical Studies: The 

 Fission Products," Books 1-3, National Nuclear Energy Series, McGraw-Hill 

 Book Company, Inc., New York, 1951. 



Pm-2. Hamilton, J. G.: The Metabolism of the Fission Products and the Heaviest 

 Elements, The Plutonium Project, Radiology, 49: 325-343 (1947). 



