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 membersof the medical team. The mean
level of Zn*? tn 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, comparedto the meanfor the
medical team of 1.72. The average K of a large
group of male employees at BNL is 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 K is proportional to the lean body mass. Thus, the K
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 measuredin
the children are somewhathigher than those of
the adults, particularly among females.
A new andveryinteresting finding ofthis study
was the determination of the presence of Co’’ in
the Marshallese population. The mean level is
fairly uniform, about % of the Zn level, but the
spread in values in any onegroup is large. There
is a fairly consistent correlation between the Zn”
and the Co” values, which could very well reflect
their commonorigin in thefish, snails, and clams
_of the Marshallese diet. The inducedactivity, Co*’,
had not been detected previously in this population because its very low level 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 gamma activityin the spectra re-
maining 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 same level of
residual activity, while the juveniles had 25 to 30%
of the adult levels. The residual activity values in
the adult groups were at 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
Re aE
SRN er om ng ema ee
important fission 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 studyof the levels of body burdensof the
several gamma-emitting radionuclides in the Marshallese people indicates howthefission products
move through the environment and accumulate
in man. Further, the biological turnoverrate of
these radionuclides in human beings can beestimated. The survey made with the portable whole-
body 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.
Summaryand 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 medicalspecialists from the United
States and 8 from the Trust Territory of the Pacific
Islands. A total of 267 Rongelap people were examined, most of them on Rongelap {sland 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 werestill concerned and
had some misconceptions about certain conditions
that theyfelt 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 ex-
pressed 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.