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Fig.6
Excretion levels of urinary C3187 and Sr**, 1954-1958
0.58 and 0.68 wc. The rise in urinary excretion parallels that of Sr%, but
the rate is much higher (Fig.6), The mean Csi37 body burden remained
about the same between 1958 and 1962, indicating an equilibrium with the
environment (Fig. 4). These levels result from the intake of Cs}" in the
Rongelap diet as well as from world-wide fall-out. The Cs?” , with its
shorter biological half-life, comes into equilibrium with the dietary level
more rapidly than Sr® , Srleveis continue to approach an equilibrium
in the Rongelap population. Cs15? is thus a better indicator of recent fallout than is Sr,
‘he mean Cs157 hody burden in 1961 for the Marshallese adult male
is about 14.7 nc;kg body weight, about 300 times the mean for the medical
team counted at the same time (48 pc/kg). The distribution of Cs)" in 1961
as a function of age,
the mean values for
non-exposed group,
values do not differ
sex and previous exposure is shown in Fig. 7. Although
the exposed group are stightly higher than those of the
the variation in each group is large and thus the mean
significantly from each other. In terms of Cs 137 /kg
body weight, there is no significant difference between the two age groups.
Females do have a lower mean value of Cs 137 /kg body weight than males.
In a study involving 6000 subjects, it was found that Csi3? /¥g body
weight is age-dependent as well as sex-dependent [14]. The authors report
that the body burden increases up to the age of 17-22 yr, followed by a
gradual fall in the ratio of Cs!%’ /kg over the life span. Females were found
to have lower Cs137 concentration per unit body weight than males by a
factor of 1.145 [14]. In both males and females the Cs157/g K ratio increased
to the ages of 22 and 17, respectively, and then remained constant over the
remaining life span [14].