33
Saiee +
uuwC,| indicates a body burden in the exposed
Rongelap group @&£280 muC (49%) with an
equilibrated body burden of 330 muC.* The Zn”
level was therefore 85% of the estimated equitlibrium level in 1958 (see Table 32).
Whole-Body Counting With
the Gamma Spectrometer
Cesium-137.
The body burdens of Cs'*’ of the
various groups studied during the 1959 surveyare
presented in Table 34. The variations in levels
within each group are quite large. If Cs'”* body
burden is expressed in units per unit body weight,
no significant difference is found between persons
older and younger than 15 years. The mean Cs'*’
level tends to be slightly lower for females than for
males, but again the difference is not significant.
ee ee ee ee ee
It is to be noted that no significant difference was
found between the Rongelap exposed, the Rongelap unexposed, and the Ailingnae groups. However, che mean Cs'*? body burden of the Utirik
group (4.3 mpC/kg) is (as in the case of Sr’)
about one-third that of the Rongelap exposed
group (12.0 muC/keg).
The mean Cs'*" body burden of the exposed
Rongelap group in 1959 was 0.57 pC (12.0
muC/kg) compared to 0.68 uC in 1958. The level
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
cs!” EXCRETION (ups LITER)
©
tissue, Cs‘*’ has a relatively short biological halflife, and thus readily reflects the environmental
1000
7
T
—
T
rs
800 F
4
600 -
4
a00F
4
ty ~ 70 OATS
200 b
4
19d [
BO
o
30
TIME
L
60
L
90
L
120
1
150
180
IN DAYS - AFTER MARCH I, 1954
Figure 56. Urinary excretion of Cs'*
emp ee tees
in exposed Marshallese.
1185603
level. The slight increase in environmentalleve!
of Cs‘** during the 1956 and 1958 periods of
weapon testing was reflected in an increased body
burden in the Marshallese. As pointed out, a very
marked increase in Cs'*’. was also observed in the
Rongelap people after they returned to theiroriginal island in 1937: the body burden in 1958 was
about 0.68 uC. about 60 times as great as in 1957,
and the urinarylevel rose by a factor of 140, be-
cause of the ingestion of Cs'** in food on Rongelap
during the 9 monthssince their return. The aver-
age Cs'*’ content of 250 Americans studied in
1958 was 6.6 muC or Yoo of the mean Rongelap
body burden.**
The average daily intake of Cs'** for an inhabitant of Rongelap in 1958 (average of 13 daily
rations) was estimated to be 3.9 muC.** This ts
about 1.3% of the nonindustrial maximum per-
missible daily intake, which is the productof the
maximum permissible concentration®’ and the
daily intake of water:
(2x 10-* wC/ml) x(1.5 «10? mi/day)
’
=300 mupC/day.
Zine-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 concentrationsin fish as early as one year
following the {954 detonation.** Body burdens of
Zn** in 1957, measured directly, averaged 44
myC in five Rongelap inhabitants (Figure 57) and
350 mpC in two Utirik inhabitants. Miller, in
1957, determined an effective half-life of 110 days
for the elimination of Zn**, which gives a biologi-
cal half-life of 200 days. 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 pC in 1958
after the return of the Rongelap people to their
istand, 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 Rongelap Lagoon were found to contain 0.6 myC win’
per lb muscle, or 7.5 mpC perlb whole fish.°*
The 1959 body burdens of Zn® are presented in
Table 35. As with Cs!3’, the variation within any
group is large, and no significant difference Is
found in Zn** per unit body weight correlated