aeapaeaeENR ate 7 ‘ =oe ee Be isBS FALLOUT FROM NUCLEAR WEAPONS TESTS excretion levels of cesiur 3’ and stronti: 1331 were measured froa March 1954 through March 1958. zinc®> levela were first measured in 1958 samples. One hundred and forty one individual urine semples collected from 24 March 1954 through 7 September 1954 were obtained by the Health and Safety Laboratory, AEC. Urine volumes were small (about 350 ml) amd it ves necessary to pool sexples. This was dona according to the age of the subjects and 19 samples of pooled urine were asgayed. A 57 Liter pocled urine sample from Rongelap was collected and assayed in 1956 (3). semples vere assayed in 1957. Three pooled samples and seven individual Thirty individual urine samples were assayed in 1958. In samples collected im 1954 and 1957 cesium 3! was scavanged by nickel photo spectrum count rate used. The 1958 samples were asanyed directly for cst37, zn05, and x40 in 2.5 liter plastic containers placed on an 8 x 4 inch (TH activated) sodium fodide crystal. The activity for each radio-isotope vas determined by gomma-rey -sSpectrel analysis. Sample activities were compared with known radio- oe , SEay A tventy chancel gamma-ray spectrum was determined for each sample and the cesium?! Hirata ferrocyanide (urine made strongly alkaline} and counted in a crystal vell counter. active standards (+ 5 percent) counted in the same geometry. Strontium’? vas precipitated from urine as the carbonate. Yttriumvas There is some uncertainty as to the completeness and the duration of time over which samples were collected am therefore twenty-four hour urine volumes are not accurately known. Potasstum4© excretion, using 360 d/m or 2 gm K/day indicates an average daily volume of about 1180 ml (+ 56 percent). It was con- venient to use one liter as an average 24 hour urine volume and to express radioassays in ricromicrocuries per liter. ve ttetetsy a | Urine samples were corrected for raifo-active decay to the time of collection. of ebMR ottrance atte, BU} separated and Identified by its half-life using thin walled gas flow counters. rf *