+2
.
CeeT
igOY
T
t
1954 ;
T
r
—
T
T
=
[at82CO
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 popula-
tion suggests that the Cs**” level, like the K*° level,
1s proportional to the lean body weight.
The mean Cs'*’ body burden of the Rongelap
ea tas
OPERATION REDWING
\
1957
{
’
1958
Cs-137
.
(
Zn-+65
{
meanofthat of the medical team carrying out the
study (0.048). The level of Cs'** tn 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 puC/g K in
June 1960 to 30 in December 1961. The body
Zr-65)
se-90 (.c02)
\
1959
adult males (14.7 mpC/kg) was 300 times the
~
$r-90 (0007)
RETURN TO RONGELAP
[ts- 137)
es- 37)
-
S*-30 1.0058)
burdens of the Marshallese will, of course, also be
-1371
1961
affected by this world-wide fallout as well as by
the fallout released in the series of tests carried out
by the USSR in October 1961. As the accumula-
\Zn-O54
Sr-90 (.0069)
ca-60
|
0.
ao
0.2
1
0.3
0.4
pec
0.5
here
0.5
0.7
Figure 58. Estimated body burdenofisotopes In Rongelap
people at various times since 1954. Values obtained either
by gamma spectroscopy or by radiochemical urine
analyses.
The levels of radioactive contamination ap-
peared to be about the same for juveniles as for
adults, for men as for women. Factors of age and
sex apparentlydo not influence significantlythe
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 contaminationis via ingestion.
Even with a fairly limited diet, individual tastes
mavdictate great differences in the food consumed.
As for the time course of the contamination in
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 burdenof the Rongelap
adult males is 14.7 mwC/kg as comparedto 14.1
in 1959. Thus, no significant change has occurred
in the past 2 years. These Cs'*’ body burdensof
the Marshallese result from the relatively high
dietary intake through foodstuffs producedin the
Marshallese environment. They reflect the level
of residualfallout on the island, and also the higher
uptake andretention of Cs'*” by food plants grown
in a K-deficientsoil. It appears that the body burden of Cs'*' has reached an approximate equilib-
tion is gradual both in the environment, as worldwide fallout settles out, and in the human body,
via the ingestive route, it will be a number of
months before a clear picture emerges. However.
after the moratorium of 3 years, during which
time the Cs'** levels had an opportunityto stabi-
lize, it will be clear what the direct results are of
that particularseries oftests.
The mean Zn"' concentration per kg body
weight of the Marshallese does not differ signifcantly betu. -n the exposed and unexposed groups.
nor does it <iiffer on the basis of sex or age. However, the mcan wasgenerallyslightly 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 droppedbya factor
of 6. The value of Zn”’ in male adult Marshallese
dropped from 9.9 muC/kg bodyweight in 1959 to
1.51 in 1961. No clear reason emergesas the basis
for this drop, although it 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
may be dueto the fact that the people are eating
more canned meats in place offresh fish. If the
Zn*° intake in the diet had decreased radically
during that period, the observedfall 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 any conclusive
statement, however.