29
their accidental exposureto fallout. During the
Residual GammaActivity, in counts/min/kg,
in Marshallese After Subtraction of K*?, Zn**, and Cs!*?
Age. vr
Rongelap exposed
Rongelap unexposed
Atlingnae
Ctirik
1-15
> 15
36.1
21.4
172
37.9
35.0
43.0
8.8
11.7
with age or sex. No significant difference was
found between the Rongelap exposed and unexposed groups, which implies that no residual Zn**
activity remains in the Rongelap people from their
original exposure.
The 1959 mean bodyburden of Zn" was 0.44
uC as compared to 0.36 wC in 1958. Thus Zn”
body burdens do not seem to have reached a
steady-state equilibrium with the environment, as
is also the case with Cs'*’. Since the source of Zn*°
is fish, which continueto be a dietary staple, the
n°’ value can be expected to increase stil! further.
The mean Utirik Zn*’ level in 1959 was about
one-third the Rongelap meanvalue.
Although Cs'*" and Zn** comprise the major
portion of gamma-emitting radionuclides present
in the Marshallese (aside from the naturally occurring K*°), residual gamma activityis still present after subtraction of K‘*, Zn®°, and Cs'*’ con-
tributions from the total spectrum in each subject (see Table 36). Analysis of the residual spectra
did not indicate any readily identifiable photo-
peaks in the short counting time employed (5 or
“Y min). This short counting time, along with the
uifficulties discussed earlier in exact calibration of
absolute activities, makes the identification of
minor photopeaks very difficult. Most of the diffi-
culties can be circumvented in future field trips by
the use of longer counting times, the use of an 8-in.
crystal, duplication of the geometry by use of the
same standard chair, and a moreprecise calibra-
tion of the phantom.
Summary and Conclusions
Continuing annua! medical surveys of the
people of Rongelap Island were carried out in
March 1959 and March 1960, 5 and 6 years after
1959 survey 76 exposed persons, including their
children, and 166 unexposed Rongelap people,
who served as a comparison population, were ex-
amined. In addition, groups of children at Uuirik.
Majuro, and Kwajalein Atolls were examined as
controls for the growth and developmentstudies
on the exposed Rongelapchildren. The {960 survey was brief, only the exposed people being
examined.
As a result of their exposure in 1954, manyof
the Rongelap people had experienced early svmptomsrelated to the gastrointestinal tract and skin.
Later they developed a significant depression of
their peripheral blood elements commensurate
with the calculated dose of gammaradiation (175
r to 64 people and 69 r to 18 people), and beta
burns of the skin along with spotty epilation. In
addition, radiochemical analyses of urine samples
showed that they had acquired a low-level bodv
burden of radionuclides. Certain other findings
were possibly related to their radiation exposure,
such as loss in weight of several pounds in most of
the people during the first several months after
exposure and suggestive evidence of slight tag in
growth and developmentof the children based on
studies of height, weight, and bone development
(but inconclusive pending verification of exact
ages of someof the children).
In spite of the depression of hemopoiesis, no
signs of radiation illness developedin the people
related to such depression, and no deaths occurred
that could be related to their radiation exposure.
No specific therapy was given. Recovery of the
peripheral blood elements, particularly lympho-
cytes and platelets, was very slow over the ensuing
years. The beta burns, which appeared about 2
weeks after exposure, were, for the most part,
superficial in nature and healed in several weeks,
with onlya few lesions showing later persisting
changes. Specific therapy was not necessary in
most cases. The hair regrew normally, beginning
at 3 months after exposure. The internally absorbed radionuclides caused no known acuteeffects
and were excreted remarkably fast with barely
detectable activity being found a yearor twolater.
On return of the people to Rongelap Island the
very low levels of radioactive contamination re-
maining there resulted in a rise in their body
burdensof cesium-137, zinc-65, and strontium-90.
The 5- and 6-year post-exposure surveys were
aimed primarily at evaluating the general medical
oe
Table 36