43
Althoughlevels of Zn** body burdens equivalent
to those found in the Marshallese (1.51 mpC/kg
body weight) have been observed in certain BNL
reactor workers,’* the values in the Rongelap
population were about 100 times those measured
in the members of the medical team. The mean
level of Zn®* in the medical team was 0.015 mpC/
kg body weight, just slightly higher than the pre-
—
cision of the counter, and therefore notstatistically
significant (Table 17).
The K content of the adult Marshallese male
averages 2.12 g/kg, compared to the meanfor the
medical team of 1.72. The average K of a large
group of male employees at BNLis 1.84 g/kg body
weight.'* The higher value for the Marshallese
males reflects their well-developed musculature
and low fat content, as the value of is proportional to the lean body mass. Thus, the K
importantfission product Sr®*. Its levels can only
be estimated from data obtained by radiochemical
analysis of urine. Undoubtedly the bremsstrahlung
resulting from the Sr®*° body burdens in the Marshallese contributes to the residual activity noted
above.
A study of the levels of body burdensof the
several gamma-emitting radionuclides in the Marshallese people indicates how thefission products
move through the environment and accumulate
in man. Further, the biological turnoverrate of
these radionuclides in human beingscan beesti-
mated. The survey madewith the portable wholebody counter has been invaluable in monitoring
the levels of internal contamination of gamma
emitters in this population. The experience gained
in this study should be of value in future surveys
amongother populations.
values for the Marshallese females are generally
lower, in the range 1.52 to 1.71 g/kg body weight.
As expected, the K concentrations measured in
the children are somewhat higher than those of
the adults, particularly among females.
A new andveryinteresting finding of this study
was the determination of the presence of Co”” in
the Marshallese population. The mean levelis
fairly uniform, about '9 of the Zn” level, but the
spread in values in anvone group is large. There
is a fairly consistent correlation between the Zn”'
and the Co" values, which could very well reflect
their common origin in thefish, snails, and clams
of the Marshallese diet. The induced activity, Co”’,
had not been detected previously in this population becauseits very lowlevel was masked by the
relatively large peaks of the other radionuclides in
the relatively short counting periods hitherto used.
It was to reveal just such secondarylevels that the
longer counting period and larger detector were
adopted for the 1961 study.
The residual gammaactivity in the spectraremaining after the subtraction of the major components indicates that there are some residual
radionuclides present in quantities not sufficient
for identification via their photopeaks. The adult
groupsall had approximately the samelevel of
residualactivity, while the juveniles had 25 to 50%
of the adult levels. The residual activity values in
the adult groups wereat least 10 times the mean
observed in the U.S. medical team. Unfortunately
whole-body counting techniques have not been
developed for external beta counting of the very
Summary and Conclusions
In March 1961, a medical survey was carried
out on the Marshallese people of Rongelap Atoll
who had been accidentally exposed to fallout
radiation 7 years previously. The medical team
consisted of 10 medical specialists from the United
States and 8 from the Trust Territoryof the Pacific
Islands. A total of 267 Rongelap people were examined, most of them on Rongelap Island and
some at Kwajalein and Majuro Atolls. Of this
number, 76 were in the exposed group: 28 were
children of exposed parents; and 163 were adults
and children from the comparison population not
exposed to fallout. The Trust Territory ship Roque
was used to transport and house the team and in
addition housed. in its cargo hold, the 21-ton steel
room with its electronic equipmentfor carrying
out spectrographic analyses.
Prior to the survey, at Rongelap a village meeting held with representatives of the medical team
revealed that the people were still concerned and
had some misconceptions aboutcertain conditions
that they felt were related to fallout such as fish
poisoning and sickness from eating arrowroot
flour. The true nature of these maladies was explained to them. Somedissatisfaction was also expressed about the continued ban on eating coconut
crabs, but the people were assured that regular
analyses for radioactivity would be run on the
crabs and they would benotified as soon as the
crabs were considered safe for consumption.