419
oo
‘
to that of the phantom, which was counted for 30
min (Figure 52).
In future whole-body counting of these people,
it will be possible, by counting for longer periods
and using an 8-in. Nal crystal, to improve the
absolute measurement of trace amounts of other
radionuclides that may be present.
Since a total of 227 Marshallese persons were
surveyed with the whole-body counter, in addition
to numerouscontrols, the spectral analyses were
performedwith the aid of a 704 IBM computer.
Radiochemical Procedures
Twenty-four-hour urine specimenswere collected in plastic bottles and sent to BNLfor radiochemical analysis. A modification of the method
of Farabee*® was used for the analysis of Sr®°. Sr
was precipitated as the alkaline phosphate, ashed
with HNO, and H,O,, and dissolved in dilute
HNO,,. After the solution was brought up toa
{-
RESULTS AND DISCUSSION
'
All three of the above methods were used for
estimating the body burdens of gamma- andbetaemitting radionuclides in the Marshallese people.
Individual values for all the people examined in
1959 may be found in Appendix 7 for gamma
spectrographic analyses and in Appendix 8 for
radiochemical analyses.
Environmental Estimate
DOE ARCHIVES
One methodused (the least quantitative) was
the environmental estimate of body burden. The
environmental estimate of internally-deposited
Sr°° was made in two ways. In the first method,
animals subsisting on diets similar to human diets
weresacrificed and their tissues were analyzed
radiochemically. A numberofrats were collected
on RongelapIsland at 2, 4, and 5 years after the
1954 accident. If the diet of these rats, primarily
plexed with EDTA,and the pH was adjusted to
5.5. The solution was then passed through an ion
land plants, was sufficiently similar to the diet of
humanbeings inhabiting this area, the rat analyses mightserve as indicators of the humaninternal
tion of 1% citric acid and 0.75% EDTAat a pH of
various tissues of these rats were measureddirectly and comparedto the ratios of the food andsoil
volume of 800 cc, the alkaline earths were com-
exchange column (Dowex-50 in the Na form),
and the column was rinsed with 300 cc of a solu-
5.0. The combined effluents contained >95% of
the total Ca. The column wasthen rinsed with 6
N HNO,to removethe Sr*°. Carrier Sr was added
to the Sr® fraction and precipitated with 70%
fuming HNO,,. Yttrium-90 was milked and counted
by the method of the AEC Health and Safety
Laboratory.**
The supernatantfrom the alkaline phosphate
precipitation was measured and divided into two
portions. One portion was scavanged for cesium
with added carrier by means of a double precipitation of the aluminum sulfate and the chloro-
platinate.”? The second portion was analyzed for
K by flame spectrophotometry.
Food samples were weighed and dry-ashed ina
muffle furnace at 800°C. The ash was weighed,
and a small portion was counted for grass beta
activity. The ash was dissolved in dilute HNO,
and processed by the method described abovefor
urine analysis.
All counting was done in a low-level beta anti-
coincidence type of counter, designed and built at
BNL. Samples were mounted on glassfiber filter
discs with nylon rings and discs and Mylarfilm.
Samples were counted against NBS standards
processed and counted underidentical geometry.*"
Tr rapemw
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radiation contamination. The Sr°°/Caratios of
on Rongelapcollected at the same time; thatis, the
environmental contamination was compared with
the directly measured contamination in animal
tissue. Extrapolation of the environmental data
gives the equilibrium value which can be expected, whereas the direct measurement gives the
value at the time of measurement (and thus the
percent of the equilibrium value for the individual
radionuclides).
The Sr°°/Caratios for different plant foods on
Rongelap varied greatly, and the diet of the rats
was too uncertain for an “average” diet to be assumed. Therefore, for a body burden estimateit
was necessaryto use the Sr°°/Ca values ofthe soil
itself.
The “‘strontium-calcium observed ratio” (OR)
of Comar*? was used to denote the preferential
utilization of calcium in the following manner:
OR gampie-precursor =
Sr/Ca of sample
Sr/Ca of precursor
The Sr®° discrimination ratio in the chain from
soil (s) to bone (6) via plants ( ) can be expressed
as follows:
OR,_,=(OR,_,)(OR,.,)=(0.7)(0.25)=0.18.
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