EPA-600/3-76-025
March 1976
ENVIRONMENTAL
PROTECTION
AGENCY
Ecological
LIBRARY
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal
species, and materials. Problems are assessed for their long- and short-term
influences. Investigations include formation, transport, and pathway studies to
determine the fate of pollutants and their effects This work provides the technical
basis for setting standards to minimize undesirable changes in living organisms
in the aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/3-76-025
March 1976
BIOLOGICAL TRANSFER OF PLUTONIUM VIA IN VIVO
LABELED GOAT'S MILK
By
William W. Sutton
Anita A. Mullen
Stephen R. Lloyd
Robert E. Mosley
Monitoring Systems Research and Development Division
Environmental Monitoring and Support Laboratory
Las Vegas, Nevada
ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 89114
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DISCLAIMER
This report has been reviewed by the Environmental Monitoring and
Support Laboratory-Las Vegas, U.S. Environmental Protection Agency, and
approved for publication. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
ii
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CONTENTS
Page
Disclaimer ii
List of Photographic Plates iv
List of Figures v
List of Tables vi
Acknowledgments vii
Conclusions 1
Recommendations 1
Introduction 1
Materials and Methods 3
Results and Discussion 6
References 17
iii
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LIST OF PHOTOGRAPHIC PLATES
PLATE Page
1. Dosing of juvenile goats using a bottle and nipple 4
2. Dosing of rats using a syringe and appropriate needle 4
modification
3. Rat sacrifice illustrating the technique used to 5
remove the pelt from the carcass
iv
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LIST OF FIGURES
FIGURE Page
1. Concentration of plutonium in goat milk following 9
a single intravenous injection of citrate-buffered
plutonium-238
2. Comparison between serum and milk plutonium following 10
intravenous injections of plutonium-238 on three
consecutive days (goat 1)
3. Comparison between serum and milk plutonium following 11
intravenous injections of plutonium238 on three
consecutive days (goat 2)
4. Comparison between serum and milk plutonium following n
intravenous injections of plutonium-239 on three
consecutive days
5. Total plutonium (nCi) in milk collections from three 12
goats intravenously administered 75 pCi of plutonium
per day for three consecutive days
v
-------
LIST OF TABLES
TABLE Page
1. Percent of Total Intravenous Plutonium Dose Retained 7
in Selected Tissues from Lactating Dairy Goats That
Received 75 yCi of Citrate-Buffered Plutonium Per
Animal Per Day for Three Consecutive Days
2. Percent of Intravenous Plutonium Dose Retained in 8
Selected Tissues from Lactating Dairy Goats Thirty
Days After Receiving 5Q yCi of Citrate-Ruffered
Plutonium-238
3. Percent of Total Plutonium Dose Retained in 13
Selected Tissues from Four Juvenile Goats That
Received Three Oral Doses of Plutonium-238
Contaminated Milk Per Day for Four Consecutive
Days
4. Mean Percent of Total Plutonium Doae Retained 14
in Liver and Carcass from Adult Rats That
Received Three Oral Doses of Plutonium Contami-
nated Milk Per Day for Four Consecutive Days
5. Mean Percent of Total Plutonium Dose Retained 15
in Liver and Carcass from Juvenile Rats That
Received Three Oral Doses of Plutonium
Contaminated Milk Per Day for Four Consecutive
Days
VI
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ACKNOWLEDGMENTS
The authors would like to express their appreciation to Mr. Cletus
Feldt and Mr. Kenneth Giles for their help on the rat sacrifice phase
of this study. Thanks are also extended to Dr. Gilbert Potter for
his critical review of the manuscript and to Dr. Robert Kinnison for
his assistance with the experimental design. Rat carcasses and livers
were analyzed by Eberline Instrument Corporation.
vii
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CONCLUSIONS
1. Plutonium concentrations in goat milk have shown that approxi-
mately one percent of the intravenous dose (citrate-buffered plutonium
nitrate, pH 4) was secreted in the milk during the first week post-
injection. No differences in the plutonium transfer rate to milk
were noted between plutonium-238 and plutonium-239.
2. There was little or no indication of basic differences in the
amount of plutonium retained in the tissues of juvenile goats and
rats following ingestion of either in vivo or in vitro plutonium
labeled milk.
3. As expected, juvenile rats retained a greater percentage of the
orally administered plutonium in the tissues than did the adult rats.
This retention difference was noted for both plutonium-238 and for
plutonium-239.
RECOMMENDATIONS
Nutritional factors affecting the biological availability of
ingested plutonium should be determined by future experiments. In vitro
and in vivo projects should assess gastrointestinal absorption of
plutonium as affected by 1) mineral constituents, 2) complexing or
binding factors, and possibly, 3) vitamin deficiencies. This is
especially important in regard to potential variations in intestinal
uptake, tissue distribution and subsequent excretion of ingested
plutonium in laboratory and domestic animals as effected by chronic
states of iron deficiency and iron loading.
INTRODUCTION
It is anticipated that with the increased use of nuclear power
systems plutonium will be produced in greater quantities and could
present a major health and ecosystem hazard. The long physical and
biological half-life and high relative toxicity have dictated that
considerable effort be devoted to quantifying plutonium transport
through the various trophic levels.
-------
Despite the fact that biological transport of plutonium has been
studied for many years, quantitative values for its transfer to milk,
and its subsequent uptake by suckling animals have not been established.
In an early plutonium metabolism study on rats , Scott et al. (1948)
observed that the average value for gastrointestinal absorption of
plutonium using three different valence states was approximately
7.0 X 10" 3 percent. Comparative studies on the intestinal uptake of
plutonium nitrate revealed no significant differences in total absorp-
tion between the rat and pig (Weeks et al. , 1956). These results were
quantitatively similar to those obtained in a rather extensive report
by Katz et al. (1955) which, following a chronic oral plutonium treat-
ment to rats, presented the mean gastrointestinal absorption and re-
tention value at 3.0 X 10-3 percent of the administered dose.
While investigating the effects of plutonium on mice treated -In
utero, Finkel (1947) discussed the relative concentrations of this
element which had been transported across the placenta or through the
milk following parturition. Despite the early realization that plu-
tonium could be transported via the systemic circulation to milk,
essentially no work was reported on the major milk producers, i.e.,
ruminants. In 1964 Sansom studied the transfer of ingested plutonium
oxide to bovine milk but observed that the results may have been in-
fluenced by fecal contamination. McClellan et al. (1962) injected two
Suffolk sheep with citrate-buffered plutonium nitrate in order to
establish a milk to plasma ratio. Although this study with sheep pre-
sented a milk to plasma reduction factor of 2.5 X 10~^, it did not
make reference to the subsequent biological availability of this in
vivo plutonium labeled milk when ingested by juvenile animals. How-
ever, Ballou (1958) had previously reported that in day-old rats plu-
tonium absorption was 85 times that in the adults and that the amount
absorbed dropped abruptly in 21-day-old rats to near adult levels.
The basis for this study is that man and especially children con-
sume large quantities of dairy products so that any evaluation of
radiological hazards associated with a plutonium contaminated environ-
ment must consider the biological availability of in vivo plutonium
labeled milk. The investigation was therefore designed to establish
the rate of plutonium-238 and plutonium-239 transport to milk in the
dairy goat. Furthermore, the study was conducted to provide order of
magnitude comparisons on the biological availability of in vivo and
in vitro plutonium labeled milk, as well as to observe the effect of
animal age on the gastrointestinal uptake of the plutonium doses. Re-
sulting information will be of value in designing definitive projects
using dairy cattle. The use of both a ruminant and a rodent species
will also be advantageous if subsequent extrapolations are made to
other mammals, as in the case of plutonium transport models.
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MATERIALS AND METHODS
Three adult lactating goats (mean weight 49 kg) were maintained in
specially constructed metabolism stalls. Citrate-buffered plutoniutn
nitrate was administered to the goats intravenously in doses of 75 yCi
per animal per day for three consecutive days. Prior to the intra-
venous dosing, a sample of known activity was removed from a stock
solution of plutonium nitrate and made up to volume with a citrate
buffer. Approximately 3 ml of the resulting solution (pH 4) was then
aspirated into a 5-ml syringe for injection. Two goats received
plutonium-238 and one goat received plutonium-239. Blood samples, sub-
quently separated into serum and formed elements, were collected
from each animal daily. Five days after dosing one plutonium-238
injected goat was sacrificed by anesthetic overdose. The remaining two
goats were sacrificed 28 days after dosing. Samples of liver, bone,
muscle, kidney, spleen and blood were collected for analysis.
During this study the goats were hand-milked at eight-hour inter-
vals and portions of milk were 1) fed to juvenile goats, 2) fed to
adult and juvenile rats, and 3) analyzed for plutonium content. In
vitro plutonium labeled milk was also fed to separate groups of juve-
nile goats and rats. The in vitro labeled milk was prepared by the
addition of citrate-buffered plutonium nitrate to uncontaminated goat's
milk. This in vitro preparation was thoroughly shaken and samples
were removed for plutonium analysis just prior to dosing the kids and
rats.
Four juvenile goats, one to three weeks of age with a mean weight
of approximately 5 kg, received the oral doses of either the in vivo
plutonium-238 labeled milk taken from the adult goat or the in vitro
plutonium-238 labeled milk adjusted to the same plutonium concentration
as the in vivo labeled milk. Dosing was accomplished with a bottle
and nipple three times a day for four consecutive days (plate 1) . The
four juvenile goats were sacrificed on the third post-treatment day at
which time samples of liver, bone, kidney, spleen and blood were taken.
Groups of adult and juvenile (12 to 14 days old) Wistar rats were
given a series of either plutonium-238 in vivo labeled, plutonium-238
in vitro labeled, plutonium-239 in vivo labeled, or plutonium-239 in
vitro labeled milk. Control animals received a placebo series of un-
contaminated goat's milk. A dosing syringe with an appropriate needle
modification was used to feed the rats (plate 2). Synthetic rat's
milk would probably have been more nutritionally balanced for these
rodents, however, supplemental rat feed and water were provided.
Dosing took place three times a day for four consecutive days, therefore
a total of 12 individual doses was given to each animal. In addition
to the four basic treatment categories there was also a division with-
in each treatment group based on the total concentration of plutonium
administered. One subgroup was given essentially two times (2x) as
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Plate 1. Dosing of juvenile goats using a
bottle and nipple.
Plate 2. Dosing of rats using a syringe and
appropriate needle modification.
much total plutonium as the other subgroup (x). The 2x treatment rats
received either portions of the milk secreted by the plutonium-injected
adult goats or an in vitro preparation equal in plutonium concentration
to the in vivo labeled milk. The x treatment groups received milk with
one half the secreted plutonium concentration as each x dose consisted
of an equal volume of contaminated milk and uncontaminated goat's milk.
As mentioned above, control rats received uncontaminated goat's milk.
Rat breeding cages with solid bottoms containing wood shavings as
bedding material were used for the juvenile rats while adult rats were
maintained in mesh bottom cages over trays containing absorbent paper.
Bedding material and absorbent paper were changed every second day
throughout the study. Groups of adult rats were sacrificed at day 2
and day 7 after the dosing sequence was completed. Juvenile rats were
originally scheduled to be sacrificed at these time intervals, however,
all juveniles were sacrificed on post-treatment day 2 because of some
unexpected juvenile deaths. The liver and the carcass of each rat were
-------
collected at time of sacrifice. Pelts and gastrointestinal tracts,
which, might have been contaminated with unabsorbed plutonium, were
carefully removed and discarded (plate 3).
Plate 3. Rat sacrifice illustrating
the technique used to remove
the pelt from the carcass.
Rat carcasses and livers were analyzed for plutonium content by
means of electrodeposition and alpha spectrometric analysis. At time
of analysis, whole samples were dry-ashed in a muffle furnace at a max-
imum temperature of 550° C. then dissolved in 8 N nitric acid and spiked
9 it ? ? "3 ft ? 3 f~> z. T 9
with a tracer isotope ( Pu for Pu samples and Pu for Pu
samples). Samples were wet-ashed to remove organic material, the ash
was redissolved, and the valence adjusted to plutonium (IV). Following
an extraction and back-extraction procedure, the samples were electro-
plated and counted on an alpha spectrometer.
The other samples (goat tissues, milk, blood, etc.) were counted
on a Phoswich detector provided with a single channel analyzer, timer,
sealer and printout set for the 17 KeV x-ray from the plutonium iso-
topes. The system was calibrated for each geometry and the concentra-
tions were considered to be nondetectable when the counting error
(background plus 2 a) reached 30 percent. Duplicate samples of milk
were taken at each collection and both sets were counted periodically.
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RESULTS AND DISCUSSION
Plutonium tissue distribution patterns in the intravenously in-
jected adult goats were basically similar to the tissue patterns
reported in other species (Rosenthal et al. , 1972) . As noted in
Table 1, the plutonium-238 concentrations in liver substantially
decreased between sacrifice day 5 and 28, while bone concentrations
of plutonium-238 showed an increase during this interval. Since only
portions of the skeleton were analyzed, some assumptions were made in
order to estimate the total osseous retention. For the purposes of
this study, plutonium concentrations from goat rib and femur samples
were averaged to arrive at bone concentrations. Total plutonium con-
tent in bone, as well as that for muscle and blood, were measured
based on calculated organ weights using the respective percentage of
body weight reported by Davis et at., 1975.
Variations in the osseous burdens between the plutonium-238 and
plutonium-239 dosed animals (noted at the 28-day sacrifice, Table 1)
were fairly large. The main non-experimental difference in these two
goats was the wide range in animal age. Considering the close resem-
blance of the other retention values, as well as the plutonium concen-
trations in milk, it appears unlikely that the observed bone burden
differences indicate a basic variation in the general deposition
pattern following administration of these two plutonium isotopes.
For comparative purposes, the percentage of plutonium retained in
the tissues of a lactating goat following an acute dose of 50 yCi
plutonium-238 is shown in Table 2. This information was taken from an
unpublished preliminary study by Stanley and Mullen (1971). Citrate
buffer was added to plutonium nitrate and the resulting solution
(pH 4) was injected intravenously. The goat was sacrificed 30 days
after dosing. As with the three goats used in the current study, the
largest percentage of plutonium was retained in the liver and values
for the spleen and muscle were also comparable. However, the fraction
retained in bone after the single injection was lower than expected.
Plutonium transported to milk as a result of the acute injection is
presented in Figure 1 as a percent of dose per ml of milk. The total
secretion of plutonium in milk 18 days following injection was approx-
imately one percent of the acute dose.
Plutonium concentration in the systemic circulation is a primary
physiological variable influencing subsequent transfer to milk. An
indication of this was found during the dosing days and during the
first three post-treatment days (Figures 2, 3, and 4). Figure 5 shows
the comparative total nCi of plutonium secreted in the milk for these
-------
TABLE 1. PERCENT OF TOTAL INTRAVENOUS PLUTONIUM DOSE RETAINED IN
SELECTED TISSUES FROM LACTATING DAIRY GOATS THAT RECEIVED 75 yCi
OF CITRATE-BUFFERED PLUTONIUM PER ANIMAL PER
DAY FOR THREE CONSECUTIVE DAYS
Adult Goat No.
Plutonium Isotope
Total I.V. Dose (yCi)
(buffered in citrate)
Sacrifice Weight (kg)
Animal Age (y)
Sacrifice Time
(days post treatment)
Average Daily Milk
Production (kg)
8 day average
30 day average
Percentage of Total
Dose Secreted in Milk
128 h post
672 h post
Biological Half-Life
of Plutonium in Milk
(h)
Percentage of Total
Dose Retained in
Tissues
Blood
Liver
Muscle
Kidney
Spleen
Rone
1
238p
Pu
225
44.6
4
5
4.6
1.0
9.0 X 10"2
53.6
8.0 X 10"j
2.0 x 10';);
3.0 X 10
6.0
2
238p
Pu
225
45.9
2
28
3.0
2.7
1.6
2.0
9.28 ± 1.85
108 + 13.3
>656
1.0 X 10"1
14.0
1.0
1.2 X ID"*
8.0 X 10
13.2
3
239p
Pu
225
50.9
10
28
1.3
2.6
1.0
1.1
12.6 ± 1.57
84.2 ± 9.34
>700
4.0 X 10"1
13.2
4.0 X 10~3;
9.0 X 10
1.0
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TABLE 2. PERCENT. OF INTRAVENOUS PLUTONIUM DOSE RETAINED
IN SELECTED TISSUES FROM LACTATING DAIRY GOATS THIRTY
DAYS AFTER RECEIVING 50 pCi OF CITRATE-BUFFERED PLUTONIUM-238
Tissue
Muscle
Bone
Liver
Lungs
Heart
Brain
Spleen
pCi/g
32.4
58.7
15.0 X 103
96.5
82.6
157.0
147.1
Percent of Dose
Retained
1.3
4.4 X 10"1
25.0
7.2 X 10"2
3.4 X 10"2
3.3 X 10"2
3.2 X 10"2
goats. There were slightly different plutonium concentrations at peak
activity as well as variations in the time to peak activity between the
three goats. The obvious complicating factors of biological variability
between animals, counting error, the multiple dose type of treatment,
and the sampling interval suggest that a detailed comparative analysis
of the plutonium secretion curves for milk would be of doubtful signi-
ficance. However, the percentage of total dose secreted in the milk
176 hours after the initial plutonium dose (128 hours post-treatment)
was 1.0, 1.6 and 1.0 for the two plutonium-238 injected goats and the
one plutonium-239 injected goat, respectively. Biological half times
for plutonium in the milk fraction are presented in Table 1.
As indicated in Table 3, the total oral dose given to the four
juvenile goats falls generally into two dose levels. These two sets
exist (kid 1 and 3, plus kid 2 and 4) because kids 1 and 2 were given
in vivo labeled milk from different adult goats, and therefore received
different amounts of plutonium per ml of milk ingested. As mentioned
earlier, kids 3 and 4 received in vitro labeled milk essentially equal
in plutonium concentration to that received by kids 1 and 2. Since the
dose was not adjusted to animal weight (nCi/kg) these two dosage levels
are by no means clear separations. However, the percentage of plutonium
retained in selected tissues is given for each individual animal.
-------
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Figure 1.
Concentration of plutonium in goat milk following a single
intravenous injection of citrate-buffered plutonium-238
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Figure 3. Comparison between serum and milk plutonium following
intravenous injections of plutonium-238 on three
consecutive days (goat 2)
123123"* 6 & 1O 12
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TREATMENT POST TREATMENT nAV
,0 12 14 16 18 2O 22 24 26
Figure 4.
Comparison between serum and milk plutonium following
intravenous injections of plutonium-239 on three
consecutive days
11
-------
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16 24 32 4O 48 56 64 72 8O 88 96 1O4 12O 128 144 152 168176
TIME (HOURS)
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Figure 5. Total plutonium (nCi) in milk collections from three goats
intravenously administered 75 yCi of plutonium per day for
three consecutive days
If liver and bone had been the only kid tissues analyzed, there might
have been a suggestion of greater retention in the -in vivo labeled
group. There was also a suggestion of greater retention for juvenile
goats which received the high plutonium dose, irrespective of in vivo
or in Vitro preparation. However, within-group variability in plutonium
concentrations for the kid tissues was great in both groups on a pCi/g
of sample basis. Extrapolations to a percentage of dose retained per
organ obscure this variability somewhat and further studies with larger
numbers of kids are probably necessary before final conclusions are
reached. Based on all juvenile goat tissues analyzed during this
study, there seems to be no clearly discernible difference in the total
intestinal absorption of in vivo and in vitro labeled milk, nor in the
gross tissue deposition pattern following these respective treatments.
17.
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TABLE 3. PERCENT OF TOTAL PLUTONIUM DOSE RETAINED IN SELECTED
TISSUES FROM FOUR JUVENILE GOATS THAT RECEIVED THREE
ORAL DOSES OF PLUTONIUM-238 CONTAMINATED MILK PER
DAY FOR FOUR CONSECUTIVE DAYS
Juvenile Goat No.
Sacrifice weight (kg)
O O Q
Total Oral Pu Dose
(nCi)
Age at Beginning of
Study (days)
Percent of Total Dose
Retained in Tissues
(3 days post treatment]
Blood
Liver
Kidney
Spleen
Bone
In Vi.V3 Lab-led Milk
1
4.7
383
8
2.0 X 10"^
i.o x 10";!,
2.0 X 10
1.0 X 10 ,
5.0 X 10
2
3.7
1008
5
2.0 X 10"^
3.0 X 10",
5.0 X 10",
1.0 X 10
1.0
In Vitro Labeled Milk
3
8.1
388
23
fa.O X 10"^
5.0 X 10",
3.0 X 10 ,
2.0 X 10"f
2.J X 10
4
5.1
1103
12
7.0 X 10"^
9.0 X 10",
6.0 X 10 2
6.0 X 10",
6.0 X 10"
Rats were also studied during the project for purposes of compari-
son and because each dosing sequence could be administered to larger
numbers of these laboratory animals. Table 4 shows the mean percent
of dose retained in liver and carcass (pelt and gastrointestinal tract
removed) from adult rats that received the complete dosing sequence.
Italicized values (alternate rows) indicate that groups of adult
rats were sacrificed seven days after termination of the oral plutonium
dosing. The other adult rats were sacrificed two days after dosing.
Values for juvenile rats are given in Table 5, but in this case all
animals were sacrificed approximately two days post-treatment. A
total of 12 individual doses was given to each animal and the average
total dose is also indicated in these tables. An average total dose
was used since there were occasional slight variations in the amount
actually ingested and the doses were not adjusted to the individual rat
weights. In addition to the basic treatment categories there was also
a division of animals based on the total concentration of plutonium
administered and it will be recalled that the study was designed to
include two main subgroups per treatment, one of which would receive
essentially two times more total plutonium than the other subgroup.
13
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TABLE 4. MEAN PERCENT OF TOTAL PLUTONIUM DOSE RETAINED IN
LIVER AND CARCASS FROM ADULT RATS THAT RECEIVED THREE
ORAL DOSES OF PLUTONIUM CONTAMINATED MILK PER
DAY FOR FOUR CONSECUTIVE DAYS
Mean Percent of Dose
Treatment Group
238,, .
Pu ^rt vivo
labeled
O OQ
Pu in vitro
labeled
239
Pu in vtvo
labeled
239
Pu in w,tro
labeled
No. of
Animals
6
6
6
6
6
6
6
6
5
5
6
6
6
6
5
6
Mean Oral Dose
(total pCi)
3374
3352
7068
7006
3708
3764
7485
7460
4507
4528
9090
9084
5010
5010
10024
9997
Retained
Liver
4.4 X 10" [
1.2 X 10~2
2.3 X 10"3
7.1 X 10~3
7.6 X 10"1
1.3 X 10~3
1.3 X 10"5
1.8 X 10~3
1.2 X 10~2
9.7 X 10~3
1.6 X 10"3
2.4 X 10~3
S.2 X 10"3
1.0 X 10~2
7.5 X 10"2
5.1 X 10~3
in Tissues
Carcass
2.4
3.7 X 10~2
2.4 X 10"2
2.3 X 10~2
5.7
8.5 X 10~2
5.3 X 10"2
4.6 X 10~2
1.4 X 10"2
2.0 X 10~2
1.3 X 10"2
1.3 X I0~l
-2*
5.6 X 10
2.0 X W~2
1.5 X 10"1
2.4 X 10~2
NOTE: Italics = 7 day sacrifice
*Based on three rats
14
-------
TABLE 5. MEAN PERCENT OF TOTAL PLUTONIUM DOSE RETAINED IN LIVER
AND CARCASS FROM JUVENILE RATS THAT RECEIVED THREE ORAL
DOSES OF PLUTONIUM CONTAMINATED MILK PER DAY
FOR FOUR CONSECUTIVE DAYS
Treatment Group
2380
Pu
238D
Pu
239p
Pu
239D
Pu
in vivo
labeled
in vitro
labeled
in vivo
labeled
in vitro
labeled
No. of
Animals
7
9
9
10
4
5
9
5
Mean Oral Dose
(total pCi)
897
1737
942
1882
1137
2257
1251
2469
Mean Percent of Dose
Retained in Tissues
Liver
5
b
2
S
6
2
3
.0
1
.1
.3
.5
.8
.8
.4
X 10"1
.1
X 10"1
X 10
X 10"1
X 10
X 10"1
X 10'1
Carcass
6.
5.
9.
4.
6.
7.
4.
5.
4
4
1
1
9
0
9
1
Several specific points of comparison were therefore possible
from the tissue retention information on adult and juvenile rats. As
stated above, these comparisons include observations on the relative
biological availability of (1) in vivo and in vitro plutonium labeled
milk, (2) different plutonium concentrations ingested within a treat-
ment group, (3) isotopic differences between plutonium-238 and
plutonium-239, plus (4) differences in tissue retention as related to
animal age. In adult rats, occasional order of magnitude retention
differences were found after ingestion of the two respective plutonium
isotopes as well as after ingestion of in vivo as compared to in vitvo
labeled milk. However, there was little indication of any basic change
in overall plutonium availability. The only comparison point to show
a consistent trend was the observation that, as expected, juvenile rats
retained more of the administered dose than the adult animals. Com-
parisons between the percentage of plutonium retained in adult and
juvenile rats can be made with the liver values at the two-day post-
treatment sacrifice. The liver is a main initial deposition site of
intestinally absorbed plutonium and the rat liver is a relatively
easy organ to remove for analysis. At least one order of magnitude
difference was usually noted between adult and juvenile livers, and
15
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in several cases two orders of magnitude were observed. The percentage
of the oral dose retained in juvenile rat carcasses appears high and it
might be advantageous to analyze the lungs separately in future studies
to determine if exposure was intratracheal rather than intragastric.
Livers and carcasses were analyzed for background determinations
from control rats (12 adult and 12 juvenile) which had been maintained
and sacrificed along with the treatment animals. Actually, the tissue
concentrations in many of the dosed adult rats were at or only slightly
above background on a pCi/g of sample basis, and the general level of
plutonium retention in most of the dosed adult tissues was quite low.
Percentages extrapolated from adult rats at or smaller than 10~4 WOuld
fall within the background range and values smaller than 10~2 were
extrapolated as background levels for the juveniles.
Tables 4 and 5 represent a compromise approach to reporting
values from this plutonium investigation. The tissue analyses for
plutonium were conducted on an activity per gram basis not activity
per organ. Furthermore, an individual aluminum can containing either
rat liver or carcass samples frequently contained more than one liver
or more than one carcass. When a can contained more than one sample,
the samples were of course taken from animals which had received
approximately equal doses of a given plutonium treatment and had been
sacrificed at the same post-treatment time. However, the analytical
sample size (for statistical comparisons, i.e., analysis of variance)
would consequently be the number of aluminum cans analyzed per treat-
ment, not the number of animals as implied in these summary tables.
The overall increased plutonium absorption noted in juvenile rats
relative to adults was in agreement with the findings of other investi-
gators. Ballou (1958) noted that in day-old rats the gastrointestinal
absorption of plutonium (nitric acid solution) was 85 times that record-
ed for the adult. An average gastrointestinal absorption of plutonium
nitrate for adult rats was reported by Weeks et at. (1956) to be
2.8 X 10~3 percent. However, detailed comparisons between plutonium
tissue retention patterns in adult and juvenile animals are somewhat
complicated by the size of individual organs relative to the total
animal weight. For example, Sikov and Mahlum (1972) reported that
skeletal weight in the rat was approximately 24 percent of body weight
at birth, but dropped to 10 percent in the adult.
16
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REFERENCES
Ballou, J. E. 1958. Effects of Age and Mode of Ingestion on
Absorption of Plutonium. Proe. Soo. Exptl. Biol. Med. 98:
726-727.
Davis, C. N., L. E. Davis, and T. E. Powers. 1975. Comparative
Body Compositions of the Dog and Goat. Am. J. of Vet. Res.
35:309-311.
Finkel, M. P. 1947. Transmission uf Radio-Strontium and Plutonium
from Mother to Offspring in Laboratory Animals. Physiol. Zoology
20:405-421.
Katz, J., H. A. Kornberg, and H. M. Parker. 1955. Absorption of
Plutonium Fed Chronically to Rats. Am. J. Roentgenol. 73:303-
308.
McClellan, R. 0., H. W. Casey, and L. K. Bustad. 1962. Transfer of
Some Transuranic Elements to Milk. Health Phys. ,9:689-694.
Rosenthal, M. W., A. Lindenbaum, J. J. Russell, E. Moretti and
D. Chladek. 1972. Metabolism of Monomeric and Polymeric
Plutonium in the Rabbit; Comparison with the Mouse. Health Phys.
25:231-238.
Sansom, B. F. 1964. Transfer of Plutonium-239 from the Diet of a
Cow to Its Milk. Brit. Vet. J. 120:158-161.
Scott, K. G. , D. J. Axelrod, H. Fisher, J. F. Crowley, and J. G. Hamilton.
1948. Metabolism of Plutonium in Rats Following Intramuscular
Injection. J. Biol. Chem. 176:283-293.
Sikov, M. R. and D. D. Mahlum. 1972. Plutonium in the Developing Animal.
Health Phys. 22:707-712.
Stanley, R. E. and A. A. Mullen. 1971. Transfer of Intravenously
Injected Plutonium to Milk in the Dairy Goat. Unpublished
Preliminary Report. NERC-LV. Environmental Protection Agency.
Weeks, M. H., J. Katz, W. D. Oakley, J. E. Ballou, L. A. George,
L. K. Bustad, R. C. Thompson, and H. A. Kornberg. 1956. Further
Studies on the Gastrointestinal Absorption of Plutonium. Rod. Res.
4:339-347.
17
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/3-76-025
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
BIOLOGICAL TRANSFER OF PLUTONIUM VIA IN VIVO LABELED
GOAT'S MILK
5. REPORT DATE
March 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
William W. Sutton, Anita A. Mullen, Stephen R. Lloyd,
and Robert E. Mosley
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Environmental Monitoring and Support Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
10. PROGRAM ELEMENT NO.
1FA083
11. CONTRACT/GRANT NO.
n/a
12. SPONSORING AGENCY NAME AND ADDRESS
Same as above
13. TYPE OF REPORT AND PERIOD COVERED
Final FY-74
14. SPONSORING AGENCY CODE
EPA-ORD Office of Health
and Ecological Effects
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Three lactating goats were given intravenous injections of citrate-buffered plutoniun
nitrate at a rate of 75 microcuries per animal per day for 3 consecutive days. Two
goats received plutonium-238 and one received plutonium-239. The goats were hand
milked at 8-hour intervals and portions of milk were 1) fed to juvenile goats, 2) fed
to adult and juvenile rats, and 3) analyzed for plutonium content. Five days after
dosing, one plutonium-238 injected goat was sacrificed and the remaining two goats were
sacrificed 28 days after dosing. In all three goats approximately one percent of the
total plutonium dose was transferred to the milk by the fifth post-treatment day.
Plutonium retained by the tissues was deposited primarily in the liver and bone.
In vitro plutonium-labeled milk was also fed to groups of rats and juvenile goats.
Tissue concentrations of plutonium from juvenile goats which had received either i,n
vivo or in witTO labeled milk were somewhat variable. Due possibly to this, within
group variability and the small number of animals per group (two) there were no clearly
discernible differences between treatments. The percentage of dose retained in liver
and carcass (pelt and gastrointestinal tract removed) of adult and juvenile rats was
also compared after receiving the various plutonium doses. The only comparison point
to show a consistent trend was the observation that, as expected, juvenile rats re-
tained more of the ingested dose than the adult animals.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Food
Milk
Plutonium-238
Plutonium-239
Goats
Metabolism
Biological transfer
02E
06H
06P
18B
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
28
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
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