4
wu) |oindieates a beds burden tn the exposed
Rongelap group of 280 mae © by wath an
equilibrated bods burden af 430 my Phe Zn
level was therefore 89%) ol the estimated ecuithibrium devel in 1954 (see Pable 32)
Whole-Body Counting With
the Gamma Spectrometer
Cesium-137.
The body burdens of Gs' ” of the
various groups studied during the 1959 surveyare
presentcdin Table $$ The variations in levels
within each group are quite large [fF Cs' body
burden is expressed in units per unit body weight,
no significant difference is found between persons
older and vounger than [5 vears. The mean Cs' °
level tends to be slightly lower for females than for
mates, but again the difference is not signtficant.
ft is to be noted that no significant difference was
found between the Rongelap exposed. the Ronge-
lap unexposed, and the Ailingnae groups. However, the mean Cis'” body burden of the Utirik
group (4,3 mpC/ke) istas in the case of Sr“)
about one-third that of the Rongelap exposed
group (12.0 mpC/ke).
The mean Cs'" body burden of the exposed
Rongelap group in
1959 was 0.57 aC (12.0
mpeC. ke) compared to 0.68 uC in 1958. The level
has fluctuated over the years since the ortginal
contaminating event. (See Figure 57, which shows
values obtained by whole-body gamma spectrometry and by extrapolation from urinalysis data.)
Unlike Sr°’, which ts firmlyfixed in the skeletal
tissue, Cs!" has a relatively short biological half-
life. and thus readily reflects the environmental
os? EXCRETION (uuCeLiTER)
1900
B00 +
—
rT
rT
+
~
r
4
4
E00 F
400 -F
7
tb 79 DAYS
100
9
i.
30
L
60
aL
90
Rongelap people after thes returned to their original island in 1997> the body burden in 1958 was
about O68 #C. about 60 times as great as in 1957,
and the urmnary level rose by a facter of 140, be-
cause of the ingestion of Cs! in food on Roneelap
during the 9 months since thetr return. The average Cs’) content of 250 Americans studted in
1958 was 6.6 mC or ‘ion of the mean Rongelap
bodv burden.
‘The average daily intake of Cs''’ for an inhabit-
ant of Rongelap in 1958 (average of [3 daily
ratrons) was estimated to be 3.9 mgt.’ This ts
about [.3'¢ of the nonindustrial maximum per-
mussible daily intake, which is the product of the
maximum permissible concentration’ and the
datly entake of water:
(2«K10 ' pCeml) x (1.5 10' mi /dav)
= 300 meC/day .
Zinc-65. Z.n”" was first detected by Miller”! in
[957 in the seven Marshallese examined at
Argonne National Laboratory by whole-body
spectrometry, although at had been observed in
high concentrations in fish as early as one vear
following the 1954 detonation. Bodv burdens of
7n’’ in 1957, measured directly. averaged 44
myG in live Rongelap inhabitants { Figure 57) and
350 mpC intwo Unurik inhabitants. Miller, in
1957, determined an effective half-life of [10 days
for the elimination of Zn'*, which gives a bialogical half-life of 200 davs. However, a value of 89
days was obtained for the biological half-life in
two patients over a 2-month period.“
The mean body burden of Zn’ estimated from
whole-body counting data was 0.36 4G in 1958
after the return of the Rongelap people to their
island, or 8 times the 1957 value ( Figure 37).
200
80
level. Vhe sitght increase in environmental level
of Gs! during the 1956 and 1958 periods ol
weapon lesting was reflected in an inereased bods
burden in the Marshallese o\s pointed out. a very
marked merease in Cs’ was also observed in the
i
1200
4
150
L
180
TIME iN DAYS - SFTER MARCH I 1954
Figure 56. Urinary excretion of Gs!”
in exposed Marshallese.
The estimated Zn" intake in food (2 to 4 mpC,
day) can be largely accounted for bv the Zn”
levels reported for fish. [n 1956, fish from Rongelap Lagoon were found to contain 0.6 mpC Zn"
per [b muscle, or 7 5 mut: per Ib whole fish.”
The 1959 body burdens of Zn"’ are presented tn
Table 35. As with Cs'", the variation within any
group is large, and no significant differencets
found in Zn" per unit body weight correlated