a ee i SEATSor BP FALLOUT FROM NUCLEAR WEAPONS TESTS 1331 excretion levels of ceetum 3’ and strontium”? were measured from March 195k through March 1958. Zinc® levels were first measured in 1958 samples. MATERIALS AND METHODS. One hundred and forty one individual urine samples collected frar 24 March 1954 through 7 September 1954 were obtained by the Health and Safety Laboratory, Urine volumes vere small (about 350 ml) and it was necessary to pool samples. This was done according to the age of the subjects and 19 samples of pooled urine were assayed. A 57 liter pooled urine sample from Rongelap wos collected and assayed in 1956 (3). semples were assayed in 1957. Three pooled samples and seven individual Thirty individual urine samples vere assayed in 1958. In samples collected in 1954 and 1957 cesium 3? vas sScavanged by nickel ferrocyanide (urine made strongly alkaline) and counted in a crystal vell counter. A tventy channel gamma-ray spectrum was determined for each sample and the cesium’?! photo spectrum count rate used. The 1956 semples were assayed directly for Cet 37, 2n65, and K*O tn 2.5 liter plastic containers placed on an & x & inch (TH activated) sodium iodide crystal. The activity for each radio-isotope vas determined by gamma-ray -bpectral analysis. Sample activities were compared with known radio- active standards (+ 5 percent) counted in the same geometry. Strontium? ves precipitated from urine as the carbonate. Yttrius’ wae separated and identified by ite hal?-life using thin walled gas flow counters. Urine samples were corrected for radio-active decay to the time of collection. PERC There is some uncertainty as to the completeness and the duration of time over which samples were collected and therefore tventy-four bour urine volumes are not accurately known. Potaas ium! excretion, using 360 d/m or 2 gm K/day indicates an average daily volume of about 1180 mi (+ 56 parcent}. It was con- venient to use one liter as an average 24 hour urine volume and to express radioesseys in micranicrocurtes per liter. ~> CA Ty p 5 ays - * = nl Po Aeee, Sea i Tithe , we oe AEC. ,