io emer te eed meme AY St ee ~ " ret hn ne siya he mes weet pen WSF time these isolations were done. Sometimes the final yields were more than 100%, at other times extremely low. Assuming a 50% overall chemical yield, one obtains a value of about 0.005 pc/l. of gr°9 for urine 316 a slightly lower figure than that obtained from whole urine without isolation. Ca‘? isolations were carried out on the first group of samples. observed counting rates were in the range 3 to 54 c/m. The Corrected for self absorption, decay, etc., gave values of about 2000 d/m/l as of Mar. 1, cor- responding to 0.002 ke per liter or 0.001 uc/24 hrs. Ba isolations were carried out on the first group of samples. served counting rates were in the range 31 to 150 c/m. Ob- Estimations for total activity corrected for decay and chemical yield, gave about 0.004 -c/l or 0.002 pc/24 hrs. Ru. 500 ml aliquots were taken for Pu isolation. rates were in the range 27 to 32 c/m. Observed counting Estimated content for urine 316 was 640 d/m/l as of Mar. 1, uncorrected for self absorption. This figure is too small to be worth converting into microcuries. The principal conclusions with regard to future episodes are that a) an aliquot of each urine sample should be evaporated to dryness (after adjusting pH to about 8-9 with NH,OH) and counted for p32 and b) an aliquot 4 should be either dry-ashed or wet-ashed and the residue counted for sr89, More information on the rate of excretion of sr®? by humans following a single exposure is greatly needed. Satisfactory methods for isolation of sr89 from large samples of urine are now available but it is questionable if it is necessary to go through this procedure under ordinary C€inestfitatieaschanged to Un<bu29 £ Le ki, by authority of the U.S.E.B,D.4., Per CeoL5 ZA ang reset ape me qiassification) (Bate) yy \ Wa ® By a AL C21’ chew thtot (Signatire of rerson making the change, and date) , ae = = //