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rium with the levels of Cs'** in the diet (although
this is a difficult point to ascertain). ‘The uniformity
of the Cs'*’/g K in the entire Marshallese population suggests that the Cs'* level, like the K*" level,
is proportional to the lean bodyweight.
The mean Cs'*' body burden of the Rongelap
r— OPERATION REDWING
cs-137
Zn- 65
burdens of the Marshallese will, of course, also be
affected by this world-wide fallout as well as by
the fallout releasedin the series of tests carried out
by the USSR in October 1961. As the accumula-
Sr-90 {.0069)
Co- 60
—L
o.l
4
0.2
L
0.3
i.
0.4
1
0.5
1
0.6
|
0.7
Figure 58. Estimated body burdenof isotopes in Rongelap
people at various timessince 1954. Values obtained either
by gamma spectroscopy or by radiochemical urine
analyses.
The levels of radioactive contamination ap-
peared to be about the samefor juveniles as for
adults, for men as for women. Factors of age and
sex apparently do not influence significantly the
deposition of these radionuclides. Wide variations
in the level of contamination appear amongindividuals of all groups, as might be expected when
the source of the contamination is via ingestion.
Even with fairly limited diet, individual tastes
maydictate great differences in the food consumed.
As for the time course of the contamination in
c
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the population as a whole, it is necessary to consider each radioisotope individually, as to source
of supply and discrimination ofthe soil, plant and
animallife, and the human bodyfor each isotope.
The mean Cs'** body burden of the Rongelap
adult males is 14.7 muC/kg as compared to 14.1
in 1959. Thus, no significant change has occurred
in the past 2 years. These Cs'*’ body burdens of
the Marshallese result from the relatively high
dietary intake through foodstuffs produced in the
Marshallese environment. Theyreflect the level
ofresidualfallout on the island, and also the higher
uptake and retention of Cs'*’ by food plants grown
in a K-defictent soil. It appears that the body burden of Cs'** has reached an approximate equilib-
tion is gradual both in the environment, as world-
widefallout settles out, and in the human body,
via the ingestive route, it will be a numberof |
months before a clear picture emerges. However,
after the moratorium of 3 years, during which
time the Cs'*’ levels had an opportunityto stabi-
~
mean of that of the medical team carrying out the
study (0.048). The level of Cs'*’ in the world-wide
population in July 1961 appears to have declined
from the maximum level observed in 1959. The
average value for Cs’** measured in BNL personnel, for example, declined from 59 pyC/g K in
June 1960 to 30 in December 1961. The body
ntLOEPe de ame ee re Soames AA OT Bike hil
adult males (14.7 mpC/kg) was 300 times the
$-90 (.0001)
RETURN TO RONGELAP
lize, it will be clear what the direct results are of
that particularseries of tests.
The mean Zn concentration per kg body
weight of the Marshallese does not differ significantly between the exposed and unexposed groups,
nor doesit differ on the basis of sex or age. However, the mean was generally slightly higher among
adults than in juveniles, and higher among adult
males than adult females. In the period 1959-1961
the value of Zn** body burden dropped bya factor
of 6. The value of Zn*’ in male adult Marshallese
dropped from 9.9 myuC/kg bodyweight in 1959 to
1.51 in 1961. No clear reason emergesas the basis
for this drop, althoughit is possible that dietary
variation may be responsible. It is known that the
source of Zn*in these people is from fish, which
selectively concentrate this element. Therefore, it
is possible that the decrease in Zn” levels noted
maybe dueto the fact that the people are eating
more canned meats in place of fresh fish. If the
Zn°* intake in the diet had decreased radically
during that period, the observed fall in the level
of internally-deposited Zn** would be consistent
with the effective half-life of Zn®, which is =120
days.'' The evidence that could be obtained on
this subject is insufficient to make anyconclusive
statement, however.
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1957
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