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
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time on Utirik atoll after fallput contamination, as campared to tha excretion