Contamination from Local Fallout
indigenous foods and half from imported foods. Using the above-mentioned
discrimination factor of +. the equilibrium body burden for the Rongelap people
on 67.5 wucsg of calcium daily intake (excluding land crabs in the diet) would
be approximately 17yyc/g of calcium. This is about 68 per cent of the equilibrium value estimated by Dunning (1957) and 74 per cent of that estimated
from unnalvsis data in 1958 (Woodward et al, 1959). Another effort was made
in the 1959 Medical Survey to gather samples of meals to be assayed for their
SrCa content. However, since the Marshallese were found to subsist to a
large extent on foods not indigenous to the area, such as “C”’ rations, nce and
tea, it is even more dificult nowto extrapolate from Sr°°/Ca ratios in food to
bod. burden.
It is obvious that further data on the transport of lowlevels of Sr®* and
other fission products through the ecological evcle in this and other communities
are required to assess the internal radiation hazard to human beings lising in
a fallout-contaminated area.
Estimate of Body Burden by Whole-Body Counting and Urinalysis
More rehable estimates of the Marshallese body burdens were obtained by
whole-body gamma spectrometry and by radiochemical urnalvsis. The urinary
excretion levels of Sr for 3 vears following exposure to fallout aro shown in
ngure 4. The 4- and 5-vear urmarn Sr levels were much higher following the
return of the Marshalles) to Rongelap. The eacretion rate may be expressed
ay the sum or two exponential functions. The major fraction of Sr®is excreted
with a half-life of 40 davs, and a smaller fraction is excreted with a half-life of
900 davs. These excretion rates correspond to those reported by Cowan et al
(19521 in a case of accidental inhalation of Sr*’, and were used in extrapolating
back to the 1-day Sr§* body burden of the Marshallese (Cohn et al, 1955).
The Cs*8* urinary excretion levels of the Marshallese for the 6 months immediately following exposure can be expressed as a single exponential function
with a half-life of 110 davs (figure 5). This biological half-life for Cs!37 is in
good agrcement with the value of 140 davs obtained by Andcrson et al (1957)
in a clinical tracer study.
The Rongelap body burden in 1955, per cent of equilibrium and the equihbrium value has been estimated from these excretion data (table 7) {Woodward ct al. 1959). These values are subject to some uncertainties since it was
necessary to use a number of generalizing assumptions to derive them. It is
possible to check these values using different approaches. For example, the
estimated burden of $19 in March 1958 equals 2 pyc/g of calcium and appears
to be of the right order of magnitude when compared with data provided by
bone biopsies. Two bone biopsics of vertebra and scapula on a Rongclap male
performed at this time indicated a level of about 3.8 pyc/g of calcium. Using
the normalization factor from vertebra to average skeleton (Schulert et al,
1959b), an average skeletal value of 2 pyc/g is obtained. Thus, the mean body
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