33
IRS >
uuC/l indicates a body burden in the exposed
Rongelap group e£280 muC (=49%) with an
equilibrated body burden of 330 muC.*? The Zn*°
level was therefore 85% of the estimated equilibrium level in 1958 (see Table 32).
Whole-Body Counting With
the Gamma Spectrometer
ine ee ee te
and the urinarylevel rose by a factor of 140, be-
cause of the ingestion of Cs'* in food on Rongelap
no significant difference is found between persons
older and younger than 15 vears. The mean Cs'*’
level tends to be slightly lower for females than for
males, but again the difference is not significant.
It is to be noted that no significant difference was
found between the Rongelap exposed, the Rongelap unexposed, and the Ailingnae groups. However, the mean Cs‘*? body burden of the Utirik
body burden.”
about one-third that of the Rongelap exposed
group (12.0 muC/kg).
The mean Cs'*" body burden of the exposed
Rongelap group in 1959 was 0.57 wC (12.0
has fluctuated over the years since the original
contaminating event. (See Figure 57, which shows
values obtained by whole-body gammaspectrometry and by extrapolation from urinalysis data.)
Unlike Sr®°, which is firmly fixed in the skeletal
tissue, Cs?’ has a relatively short biological halflife, and thus readily reflects the environmental
»
about 0.58 uC, about 60 times as great as in 1957,
various groups studied during the 1959 survey are
presented in Table 34. The variations in levels
within each group are quite large. [f Cs'*” bodv
group (4.3 muC/kg) is (as in the case of Sr°°)
1g00
T
T
T
T
800 -
cs'8? EXCRETION (upC/ LITER)
Rongelap people after they returned to their orig-
T
.
4
600 -
during the 9 monthssince their return. The aver-
age Cs''’ content of 250 Americans studied in
1958 was 6.6 muC or Yioo of the mean Rongelap
The average daily intake of Cs'*’ for an inhabit-
ant of Rongelap in 1958 (average of 13 daily
rations) was estimated to be 3.9 muC.*’ This is
about 1.3% of the nonindustriai maximum permissible daily intake, which is the product of the
maximum permissible concentration®’ and the
daily intake of water:
(2% 107+ uC/ml) x (1.5107 mi/day)
*
= 300 muC/day.
Zinc-65. Zn** was first detected by Miller®** in
1957 in the seven Marshallese examined at
Argonne National Laboratory by whole-body
spectrometry, although it had been observed in
high concentrations in fish as early as one year
following the 1954 detonation.*® Body burdens of
Z£n** in 1957, measured directly, averaged 44
myC in five Rongelap inhabitants (Figure 57) and
350 mpwC intwo Uurik inhabitants. Miller, in
1957, determined an effective half-life of 110 days
for the elimination of Zn®, which gives a biological half-life of 200 days. However, a value of 89
days was obtained for the biological half-life in
two patients over a 2-monthperiod.*®
The mean body burden of Zn*estimated from
whole-body counting data was 0.36 uC in 1958
after the return of the Rongelap people to their
400 f
AY
th ~? 0 DAYS
200 +
4
island, or 8 times the 1957 value (Figure 57).
The estimated Zn® intake in food (2 to 4 muC/
day) can be largely accounted for by the Zn*°
levels reported for fish. In 1956, fish from Ronge-
lap Lagoon were found to contain 0.6 myC Zn**
100
B80
0
l
30
TIME
I
60
1
30
L
a
1
120
150
180
(IN DAYS - AFTER MARCH |, 1954
Figure 56. Urinary excretion of Cs'*"
in exposed Marshallese.
|
per |b muscle, or 7.5 muC per Ib whole fish.**
The 1959 body burdens of Zn*® are presented in
Table 35. As with Cs'*’, the variation within any
group is large, and no significant difference is
found in Zn*° per unit body weight correlated
wh= -
The body burdens of Cs! of the
muC/kg) compared to 0.68 uC in 1958. Thelevel
a aee ee ee
marked increase in Cs'*" was also observed in the
inal island in 1957: the body burden in 1958 was
burden is expressed in units per unit body weight,
cae geeA WR enern cere orm
weapon testing wasreflected in an increased body
burden in the Marshallese. As pointed out, a very
ineeran a
Cesium-137.
level. The slight increase in environmental level
of Cs'** during the 1956 and 1958 periods of