Applied
of plutonium by dairy cows have been reported at previous Nevada
shing
establi
(1)
by
ken
underta
Ecology Group meetings. These studies were
absorpinitial
ng
followi
tissues
what portion of plutonium was retained in the
and
urine,
milk,
to
rted
tion; (2) determining the amount of activity transpo
the
of
forms
l
feces; and (3) observing these phenomena after various chemica
ng
occurri
factor
on
nuclide were administered orally. Due to the large reducti
s
with gastrointestinal absorption, the transport and retention characteristic
were based on relatively low levels of systemic accumulation.
Comparisons
should be made on the percentage of plutonium transported to milk and edible
bovine tissues following a larger systemic dose.
Transport coefficients are frequently valid only under experimentally defined
conditions and some reports have addressed factors that can cause variations
in plutonium uptake. Ragan (1975) noted an approximately fourfold increase
for the gastrointestinal absorption of plutonium-239 citrate in iron-deficient
mice. There was also a more rapid translocation of plutonium from soft tissues
to bone in these iron-deficient mice.
Another problem of potential concern is
whether in vivo plutonium-labeled milk represents a more biologically available
nuclide form than the various in vitro plutonium preparations typically adminThis question
istered to establish gastrointestinal transport coefficients.
is particularly relevant in reference to juvenile animals, not only because
human infants consume relatively large quantities of milk, but also because of
the increased juvenile gut absorption of plutonium in some species (Ballou,
1958).
To obtain information on the biological availability of tm vivo plutonium-labeled
milk, two closely related studies were performed and these experiments have
been outlined in this paper.
A basic objective was to compare the gastrointes-
tinal uptake of tn vivo and tin vitro plutonium-labeled milk by dairy calves.
The definitive phase of these experiments has just been completed and the
samples of primary concern, i.e., calf tissues, have not been analyzed.
paper should therefore be considered as a progress report.
This
METHODS AND MATERIALS
The experiments were conducted in two phases.
A feasibility study (Phase I)
used a total of two lactating cows and four calves, while the more elaborate
definitive study (Phase II) used four cows and twelve calves.
Phase I
Phase I was directed primarily toward confirming the approximate quantity of
plutonium for two different doses, an oral dose for calves and an intravenous
dose for the adult cows. Selection of an appropriate dose for the calves
concerned plutonium concentrations needed for the in vivo labeled milk. This
tn vivo plutonium-labeled milk would have to contain a sufficiently high
nuclide concentration to allow for the subsequent detection of plutonium in
selected calf tissues.
The second dose requiring confirmation was directly
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