63
from its bremsstrahlung spectrum, but in practice the complications caused by the presence of
gamma-rayemitters and bythesize of the human
body renderthis method infeasible.)
Comparison of the excretion rates of *°Sr and
'9™Cs with the body burdensof **"Cs measured by
whole-body counting provides a clue to the *°Sr
body burdenstatus. A quantitative value cannot
be deduced, however, because the factors relating
the behavior ofthe two nuclides are not sufficiently
well established. The study by Hardy, Rivera, and
Conard*™ summarized in Appendix 18 is pertinent
to this problem. '*’Cs and *°Sr retentions were fol-
lowed for 190 days after ingestion of representative
Rongelapfood items by one ofthe investigators.
The '*7Cs ingested was almost quantitatively ab-
sorbed from the gastrointestinal tract, but 50% of
the *°Sr was excreted via the feces in the first 10
days and maybe regarded as not having been
absorbed. By the end of the study almostall of the.
87Cs and about 75% of the *°Sr had been excreted
in the urine and feces. The exactfigure for retention is dependent on the correction used for activi-
ties ingested in the normaldiet, and these were
not measured. In this study the biological halftime for '*’Cs was estimated as 74 days. For both
'87Cs and *°Sr the urinary excretion rates were
markedly elevated during the ingestion period and
for a few days afterward. This confirmsotherre-
sults to the effect that the excretion rates found
are strongly affected by the recent diet and, when
there has been a recent intake of high activity
food, the excretion rates do not provide accurate
indices of the body burdens.
Comparison of '?’Cs Levels in Marshallese
and Alaskan Eskimos
It is ofinterest to comp.re the '*’Cs body burden
findings in the Rongelapese with those reported
for certain Alaskan Eskimos. Thefindings in the
Eskimo population in August 1965 are shownin
Table 29.%° It may be noted that the results for
adult Eskimos are equal, within statistical limits,
to those for the adult male Rongelapese. For the
Eskimo population the 1965 data run about 30%
lower than the comparable 1964 data, and this
trend parallels the findings in the local caribou,
one of the principal componentsoftheir dict.**
The Federal Radiation Council Radiation Protection
Guides*® is cited asrecommending a limit of 3000
nCi '*’Cs in individual adults for this population,
Table 29
Cesium-137 Body Burdens
for Residents of Anaktuvuk Pass, Alaska**
Body
nCi per
Age, yt
No. persons
burden, nCi
kg body wt.
>21
15-20
3-14
23
5
22
92958
490+ 42
170417
15.7+£1.0
9.5+1.0
6.20.3
16
900=-60
16.041.3
>21*
*“Controls” —- members of a group who werefirst
counved in 1963 and are re-examined periodically.
and opinions are expressed to the effect that the
current body burdens do not constitute a radiological health hazard.** These opinions are consistent with those that have governedthe policies
applicable to the Rongelapese.
Radiochemical Analysis of Coconut Crabs
A food item that has been of special interest
throughout the Rongelap medical surveysis the
coconut crab (Birgus latro). Becauseofits high *°Sr
content, it has been banned as a food. The following concentrations of °°Sr and ‘*’Cs were found in
a crab taken from RongelapIsland in 1965 (radiochemical analysis by the Health and Safety Lab-
oratory): **Sr, 66,600 pCi/kg original matter;
87s, 12,700 pCi/kg original matter; stable Ca,
92.) g/kg original matter.
Previous analyses of crabs taken from Rongelap
Island have been reported in the 7, 8, and 9-10
year reports.*-’° For *°Sr the results have run: at
7 years 1140 pCi *°Sr/g Ca; 8 years 1317, 1086,
1113, and 1378 pCi *Sr/g Ca; and 9-10 years 865,
628, and 780 pCi *Sr/g Ca, and 39,292, 45,318,
and 66,234 pCi '*’Cs/kg. The 1965 results for *°Sr
are slightly below the averagefor the previoussurvey and for '*’Cs are reduced to about % the previovs results. All these results are markedly lower
th... those that have been obtained with crabs
from the more heavily contaminated islets of
Eniatok and Kabelle (Figure 71).
The crab data may be compared with the data
on Rongelap subject No. 73, who hadthe highest
'87Cs body burden (25,400 pCi/kg) and was excret-
ingactivity in concentrationsof 78,000 pCi '3’Cs/z
Ca and 50 pCi *°Sr/g Ca. It seems clear from this
that becauseofits relatively high °°Sr content the