63
from its bremsstrahlung spectrum, but in prac-
Tabie 29
tice the complications caused by the presence of
gamma-ray emitters and bythe size of the human
Cesium-137 Body Burdens
body render this method infeasible.)
Comparison ofthe excretion rates of °°Sr and
137Cs with the bady 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 werefollowed for 190 daysafter ingestion of representative
Rongelap food items by one of the investigators.
The '°’Cs ingested was almost quantitatively absorbed from the gastrointestinal tract, but 50% of
the *°Sr was excreted via the feces in the first 10
davs and may be regarded as not having been
way
absorbed. By the end ofthe study almostall of the
Cs and about 75% of the *Sr had beensexcreted
in the urine and feces. The exactfigure for reten-
tion is dependenton the correction used for activities ingested in the normal diet, and these were
not measured. In this study the biological halftimefor '*’Cs was estimated as 74 days. For both
"Cs and %Sr the urinary excretion rates were
markedly elevated during the ingestion period and
for a few days afterward. This confirms otherre-
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
for Residents of Anaktuvuk Pass, Alaska®®
Body
nCi per
Age, vr
No. persons
burden, nCi
kg body wt.
>2i
15-20
3-14
23
3
22
92058
490442
15.72=1.0
9.51.0
>21*
16
900 60
16.0+1.3
170+17
6.20.3
*“Controls’” - members of a group who were first
counted 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 con-
sistent with those that have governed the 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 (BSzrgus fatro). Because of its high °°Sr
content, it has been bannedas a food. The follow-
ing concentrations of °°Sr and '*’Cs were found in
a crab taken from Rongelap Island in 1965 (radio-
chemical analysis by the Health and Safety Laboratory): *°Sr, 66,600 pCi/kg original matter;
87Cs, 12,700 pCi/kg original matter; stable Ca,
92.1 g/kg original matter.
Previous analyses of crabs taken from Rongelap
Island have been reportedin 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,
It is of interest to compare the ‘**Cs body burden
findings in the Rongelapese with those reported
628, and 780 pCi *Sr/g Ca, and 39,292, 45,318,
Eskimo population in August 1965 are shownin
are slightly below the average for the previoussurvey andfor '*’Cs are reduced to about '4 the previous results. All these results are markedly lower
for certain Alaskan Eskimos. The findings in the
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 findingsin the local caribou,
one of the principal componentsoftheir diet.*°
The Federal Radiation Council Radiation Protection
Guides*” is cited as recommendinga limit of 3000
nCi '3’Cs in individual adults for this population,
and 66,234 pCi '’Cs/kg. The 1965 results for °°Sr
than 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 had the highest
'37Cs body burden (25,400 pCi/kg) and wasexcreting activity in concentrations of 78,000 pCi '*"Cs/g
Ca and 50 pCi *°Sr/g Ca. It seemsclear from this
that becauseofits relatively high °°Sr content the