a
>656
wo
ana
A
108 + 13.3
om
°
iat
rio
9.28 + 1.85
da
2.0
225
od
ae
225
2439py
238p,
PLUTONIUM TRANSPORT TO MILK IN DAIRY GOATS
THAT RECEIVED 75 uCi OF CITRATE-BUFFERED
PLUTONIUM NITRATE PER ANIMAL PER DAY FOR THREE
CONSECUTIVE DAYS
recovered in the liver and muscle of the four injected cows are shown in
Table II,
When goats were used as experimental animals, approximately 1
percent of an acute citrate-buffered plutonium dose was recovered in the
milk during the first 18 days after injection. Percentages of total dose
secreted in goats’ milk following multiple plutonium injections are presented
in Table III. While many Factors were different in the respective projects,
Table IV presents a brief comparison of the above mentioned studies.
The
information is ovtlined as a percentage of the administered dose transferred
to milk.
The btological transport of plutonium, under somewhat natural grazing conditions,
has been discussed by Smith et al., (1976). This report reviewed a continuing
project on nuclide uptake by Hereford beef cattle grazing on a plutoniuncontaminated range at the Nevada Test Site. The plutonium-239 burden in
liver and muscle of a 409-kg cow, sacrificed 177 days after being introduced
“
+
225
2328p,
to the contaminated range, was 2.4 x 107" and 3.2 x 1075 percent of
the
estimated total dose.
However, when the oral dose was based on plutonium concentrations in only the tiquid fraction of rumen ingesta, the percentages
calculated for liver and muscle retention were of course higher (1.5 x 1073
and 2.0 x 10-" respectively).
Differences between total dose and available
dose in ruminants have also been discussed by Barth and Mullen (1974) and
Barth {1977 - this publication).
°
a
440
(h)
in Milk
of Plutonium
Excretion Half-life
Secreted in Milk
672 h post
128 h post
Dose
Percentage of Total
Average Daily
Milk Production (kg)
8-day average
30-day average
Total I.V. Dose (yCi)
(citrate buffered)
Plutonium Isotope
Citrate buffered plutonium and relatively insoluble particulate plutonium
dioxide have been administered orally to respective groups of laying hens
(Table V).
This work was reported by Mullen et al,, (1976). Yolk was the
only egg fraction in which plutonium activity was detected,with peak concentrations being reached 1? days after the initial ingestion. When plutonium
citrate doses were stopped, yoik concentrations of plutonium decreased rapidly
with an initial half-time of approximately 2 days as compared to a half-time
of 4.4 days afrer the termination of plutonium dioxide ingestion.
Goat Number
TABLE III
aie
na
‘os
Intravenous doses of citrate buffered plutonium nitrate have been given to
cows (Sutton et al., 1976b) and goats (Stanley and Mullen, 1971; Sutton et al.,
1976a). Approximately 1.5 percent of the intravenous dose was recovered in
cow's milk during the first 120 hours after injection. This plutonium transfer to bovine milk was somewhat greater than expected.
Percentages of dose
Figure 1 outlines some potential transport and recycling pathways for plutonium
in food products.
Plutonium's long half-life produces most of the problem.
These pathways, some of which currently represent a very minor contribution,
could become more important when long-range hazard predictions are formulated.
The main point of emphasis in this Figure is the need to examine the biological
availability of in vivo labeled food products.
Liver, meat, milk and eggs that
have been contaminated tn vivo should be fed to suitable animals (adult and
juvenile) so as to insure that the low degree of plutonium absorption does
not change under these somewhat more natural exposure conditions.
The pig,
because of certain anatomical and physiological digestive similarities to man,
might be a good experimental animal for such studies.
441