pOacne ~ vee £ > IR - -S5- .mte syatee has 8 background of abcut S@ counts per sinute ae . m@ an efficiency of approstimetely 3@ per cent based on p2z_ The coun. 3 for biclogical semples were comverted to disinteqratioms per minute per gram td'm/g} cf wet t:esue and the counts for samples of teland e011 and >ach sand were com verted to d/m’g of dry material et t:me of counting by apply tag correction factors for sample we.unt, countew efficiency, anc sl f-aensorption. The values for gross peta activity itn the appendix tables are civen .: d’/m/g pilus Or minus the % per cent counting error, which was obtained from nomograpt:s based am the rat.o of the counting rate ond total time of counting of tie sample to the counting rate and total time of counting of back rou: ¢ tables, (F.nsman, 1957). The valwee in the summary Tables 2 and 3, however, havea‘een calculated in terms cf miccomicrocuries per gram fule/’g) of wet tissue. The samples collected :n 1353 were analyzed for gammaemitting tsotopee with a 3 x }-inch sodium iodide crystal commected to a Raliation Courter “sporetary 256-channel anelyzer. The radioisotopes present in the sampies were tdenti- fied by their gamma energies anc for some of the zamples the amount of seech radioisotope was determined ene - by & suctractive sane