1332s FALLOUT FROM NUCLEAR WEAPONS TESTS RESULTS AND DISCUSSION. Cesium'37 m:cretion Levels and Body Burden The urinary excretion levels of cesitml3? for the years 1954, 1957, and 1958 are shown in Tables 1 - &. On 24 - 25 March, 1954, the mean excretion level of cesiual37 for all age groups wos 405 uuc per liter. With an excretion rate of O.46 percent (4) of cesium’3? body burden per 24 hours, the mapo body durden fron fallout 24 - 25 days efter exposure wes 405 /4. 6x20" 3 x 10° or 88 me (+ SL percent). This value is about 20 times the average body burden reported by B. C. Anderson, et al (5, 6) for people measured during 1956 - 1957 in the United States. The cesium 3? urinary excretion levels for the six months following expesure can be expressed as an exponential function, and a best line of fit deawn through the data resulted in a half time for elimination of about 110 days (Fig 1). A diological half time of about 140 days has been observed opts Be RAE on volunteers who ingested one microcurie of redio-cesium (4). gee. TE Rc aRRRn From the 1957 Cst3” excretion levels (Table 2) the Rongelap group exposed to fallout was estimated to have an average burden of about 7 muc, whereas the Rongclap control group was about 2 muc. Body burden in either group in 1957 fe cocparable to levels measured in the U. S, population (6). With a half time Ll for elimination of the order of 150 days, the body burden of the exposed Rongelap group should have decreased from the March 1954 level to 7 muc in about 550 days, or late in 1955. A body burden of 7 mc for this group in March 1957 could then indicate a continuing exposure to cals? during 1956 of the order of 22 micromicrocurics per day from stratospheric-tropospheric fallout while residing on Majuro. Since the Utirik group vas returned to thetr atoll in 1954, the mean body Durden in 1957 was elevated to an eatimated 337 muc, pone 48 times the Csl37 burden of the exposed Rongelap people who reaided on Majuro. Thia long residency tes Rie . 4 ade te SeeRos Fs Pe: t " nce be tefuelwe a what ceettl, ae a time on Utirik atoll after fallput contamination, as campared to tha excretion