S. H. COHN, R. A. CONARD, E. A. GUSMANOand J. S. ROBERTSON
21
also the higher uptake and retention of Cs!” by
food plants grown in a K-deficient soil. It
appears that the body burden of Cs!8? has
reached an approximate equilibrium with the
levels of Cs!8” in the diet (although this is a diffi-
decreased radically during that period, the
observedfall in the level of internally-deposited
_Cs87/g K in the entire Marshallese population
suggests that the Cs!87 level like K*° is propor-
statement, however.
cult point to ascertain). The uniformity of the
tional to the lean body weight.
The mean Cs!37 body burden of the Rongelap
aduit (14.7 nc/kg) males was 300 times that of
the mean of the medical team carrying out the
study (0.048 nc/kg). The level of Cs!8? in the
world-wide population in July 1961 appears to
have declined from the maximum level observed
in 1959. The average value for Cs!47 measured
in BNL personnel, for example, declined from
59 pe/g K in June 1960 to 30 pe/g K in December 1961. The body burdens of the Marshallese
will, of course, also be affected by this world-
Zn® would be consistent with the effective half-
life of Zn®5 which is approximately 120 days.'®
The evidence that could be obtained on this
subject is insufficient to make any conclusive
Whilelevels of Zn® body burdens equivalent
to those found in the Marshallese (1.15 nc/kg
body weight) were observed in certain BNL
reactor workers,2the values in the Rongelap
population were about 100 times those measured in the members of the medical team.
The meanlevel of Zn®in the medical team was
0.015 ne/kg body weight, less than or equal to
the precision of the counter, and therefore not
statistically significant (Table 2).
The K content of the adult Marshallese male
averages 2.12 g/kg, compared to the mean for
the medical team of 1.72. The average K in
October 1961. As the accumulation is gradual
both in the environment, as world-wide fallout
settles out, and in the human body, via the
g/kg of a large group of male employees at BNL
who have been studied is 1.84 g/kg body
weight.2® The higher value for the Marshallese
males reflects their well-developed musculature
and low fat content, as the value of K is propor-
the moratorium of three years, during which time
values for the Marshallese females are generally
lower, in the range 1.52-1.71 g/kg body weight.
wide fallout as well as by the fallout released in
the series of tests carried out by the U.S.S.R. in
ingestive route, it will be a number of months
before a clear picture emerges. However, after
the Cs!8” levels had an opportunity to stabilize,
- it will be clear what the direct results are of that
particularseries oftests.
The mean Zn® concentration/kg body weight
of the Marshallese does not differ significantly
between the exposed and unexposed groups, nor
doesit differ on the basis ofsex or age. However,
the mean was generally slightly higher among
adults than in juveniles, and higher among
tional to the lean body mass.
Thus, the K
As expected, the K concentrations measured in
the children are somewhathigher than those of
the adults, and particularly among females.
A new and very interesting finding of this
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 one group is
large. There is a fairly consistent correlation
adult males than adult females. In the period
1959-1961 the value of Zn® body burden
dropped bya factor of six. The value of Zn®in
male adult Marshallese dropped from 9.9 nc/kg
between the Zn® and the Co®® values, which
could very well reflect their commonorigin in
the fish, snails and clams of the Marshallese
diet. The induced activity, Co®, had not been
clear reason emerges as the basis for this
its very low level was masked bytherelatively
body weight in 1959 to 1.51 nc/kg in 1961. No
difference, 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 due to the fact that the
people are eating more canned meatsin place of
fresh fish. If the Zn® intake in the diet were
detected previously in this population because
large peaks of the other radionuclides in the
relatively short counting periods hitherto used.
It was to reveal just such secondary levels that
the longer counting period and larger detector
were adopted for the 1961 study.
The residual y-activity in the spectra remaining after the subtraction of the major
components indicates that there
are
some