Ecological Research Series
DISTRIBUTION OF INGESTED AMERICIUM IN
CHICKENS AND TRANSPORT TO EGGS
Environmental Monitoring and Support Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
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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-600/3-76-058
May 1976
DISTRIBUTION OF INGESTED AMERICIUM IN CHICKENS
AND TRANSPORT TO EGGS
By
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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INTRODUCTION
The necessity for obtaining further information concerning the fate of the
transuranic nuclides in the environment has been well established. However,
little is known about the metabolism of americium in chickens (Gdllus domesticus)
and its subsequent transfer to eggs. In the event that farm areas become contami-
nated with americium, chickens allowed to forage around such farmyards may ingest
contaminated soil and feedstuffs. This ingested americium may be metabolized and
transferred to egg contents and edible body tissues, thereby causing contamina-
tion of a portion of the human food chain.
The absorption, distribution, and excretion of the actinide elements in
biological systems are determined largely by their chemical characteristics,
which are similar to those of the lanthanides (Durbin, 1973; Hamilton, 1948).
Lanthanide fission products administered intramuscularly to laying hens were
found to be distributed throughout the tissues with a major fraction concen-
trated in the skeleton and a lesser fraction in the liver (Mraz et al., 1964).
Of the egg components, the yolk was found to contain amounts ranging from
18.1 percent of the administered dose of lanthanum-140 to 1.8 percent of the
administered dose of praseodymium-142 per four-egg composite sample.
Several investigators have found indications that plutonium and americium
may be metabolized in a manner similar to iron (Lindenbaum and Rosenthal, 1972;
Taylor, 1972). Transferrin appears to be the universal transporting protein
for plutonium (IV) in the blood plasma of all animals that have been studied.
The main route of elimination of plutonium is through the gastrointestinal
tract, via the bile and feces, which is also similar to that for iron. Laying
hens require a large amount of iron in addition to their maintenance need,
since the average egg yolk contains 1.1 mg of this element (Maynard and Loosli,
1962). If plutonium and americium are metabolized in a manner similar to that
reported for iron, then the egg yolk should contain these elements.
This study was conducted to determine the extent to which the relatively
soluble americium citrate is absorbed and distributed in the edible tissues and
egg components after oral administration to laying hens.
SUMMARY
Americium is one of the transuranic elements which, as a daughter product
of the radioactive decay of plutonium, may be found in the environment as a
result of worldwide fallout or accidental contamination. One of the routes
to man is through the food chain. This study investigated the transport
through one portion of the food chain, chickens and eggs. The soluble citrate
complex of americium-241 was orally administered to 20 white Leghorn laying
hens daily for 2 weeks. The yolks, whites, and shells from the eggs were
analyzed for their americium content. Yolk was the only egg fraction in which
-radioactivity was observed. The americium-241 activity in yolks reached a
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maximum on the 14th day of dosing indicating that equilibrium had not been
reached and additional transfer of americium to yolk would have occurred if
dosing had continued. Analysis of egg yolk yielded a two component excretion
curve with biological half-times of 2.00 ± 0.18 days and greater than 33 days,
indicated by the average concentration values of americium-241 in yolks laid
after the maximum activity was reached.
The hens were serially sacrificed at 1, 10, and 20 days after the final
administration of americium-241. Tissue samples were collected and the
americium content determined in the edible portions and feathers of the hens.
Americium was detected in most tissues at early times with the main concentra-
tion in the liver and skeleton. The highest concentration per organ (3.03 X
10~3 percent of the dose) occurred in the liver of hens sacrificed 10 days
after final administration of americium-241.
In a contaminated farmyard where chickens are raised with equal likeli-
hood of consuming equivalent proportions of plutonium and americium, the
americium would present the greater hazard to those persons eating eggs and/
or chicken liver from that source.
CONCLUSIONS
Ingestion of the relatively soluble citrate form of americium-241 by
laying hens resulted in the contamination of the egg yolks and the concentra-
tion of americium-241 in the skeletons and livers of the hens. The activity
per egg yolk continued to increase during the 14 days of americium ingestion,
indicating that equilibrium had not occurred and that americium concentration
may increase in yolks for a much longer period of time. It appears that more
americium-241 concentrates in egg yolk and chicken liver than plutonium-238
when ingested in the relatively soluble citrate form. This concentration
should be recognized when contaminating events occur in the vicinity of a
farming area.
RECOMMENDATIONS
Although little hazard to humans would be expected from ingesting americium-
241 contaminated eggs or chicken livers, the possibility of this contamination
must be recognized in the event of the contamination of farming areas. Further
study would determine the concentration of ingested americium oxide, the most
probable form of released americium. The biological availability of the
organically incorporated americium should be investigated. Knowing the genetic
effects of americium on chicks hatched from contaminated eggs and the concentra-
tions of americium in these chicks and its transfer ability to their eggs after
they reach maturity would be of additional help in evaluating the hazard of
americium in the environment.
EXPERIMENTAL PROCEDURES
Thirty white Leghorn laying hens were housed in stainless steel animal
metabolism cages with a center partition arranged to allow each hen to have
an individual cage area. Excreta were collected in paper-lined trays beneath
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the wire mesh. The cages were cleaned daily to decrease airborne contamination
and to keep the eggs clean.
The chickens were acclimated to their surroundings for several weeks prior
to the study. During the study, the chickens were maintained on commercial
laying pellets and had access to water and oyster shell.
The chickens used in this study were beginning their second laying cycle
and were about 2 years of age.
SOURCE PREPARATION
The solution for dosing was prepared fresh daily from americium-241 (III)
nitrate and citrate buffer (pH 3.5 to preserve the monomeric state) and will
be referred to as americium citrate. This preparation allows better comparison
with previous experiments in which plutonium solutions were prepared similarly.
DOSING
Each of the 20 hens was administered 2 microcuries of americium-241 citrate
orally by means of a dosing needle and syringe every day for 2 weeks.
Ten control hens were caged randomly among the dosed chickens. The control
hens did not receive a placebo, but were used only as biological samplers to
measure any cross-contamination.
SAMPLE COLLECTION AND STORAGE
Eggs were collected daily. After washing they were broken and the whites,
yolks, and shells were separated. The separated fractions were weighed, placed
in counting containers, and refrigerated until analyzed.
Six hens were sacrificed at 1 day, seven hens at 10 days, and seven hens
20 days after final dose administration. After sacrifice and exsanquination,
tissue samples consisting of gizzard, heart, liver, and muscle were collected to
determine the amount of americium present in the edible tissues. Feathers
were collected to ascertain if the concentration of americium occurred there-
in. The feathers were washed with a commercial decontamination solution placed
in an ultrasonic generator prior to analysis to remove accumulated surface
contamination.
SAMPLE ANALYSIS
The counting containers were covered with plastic film and turned film-
side down on the thin window crystal detector of a FIDLER instrument. The
detector was housed in a standard shield and coupled to a RIDL single-channel
analyzer system with sealer readout. This system was calibrated for various
sample types and weights. Sample collection was stopped when the counting
error exceeded 30 percent.
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RESULTS AND DISCUSSION
In order to follow the possible mechanisms for absorption of americium
by chickens and its subsequent transfer to eggs, it is necessary to review
some of the physiology of digestion and egg production. The following infor-
mation is excerpted from P. D. Sturkie's (1970) treatise on the subject.
Digestive organs of chickens are similar to those of mammals except that
birds have a gizzard and a crop. The crop is formed as a dilatation of the
esophagus and is a storage organ. The proventriculus of the bird is comparable
to the simple glandular stomach of mammals. The gizzard is a highly special-
ized organ for grinding, as the bird has no teeth.
Rate of passage of food through the alimentary canal is influenced by the
consistency, hardness, and water content of the food and the amount consumed.
If the crop is full, it requires 10 to 18 hours for all of the food to leave
the crop. In experiments with dye-impregnated food, it was indicated that
the dye can be detected in the feces within 24 hours of administration. When
radioactive barium was administered to chickens, it appeared that approximate-
ly half the activity was excreted in 4 to 5 hours.
Although information about digestion is meager, the evidence indicates
that little digestion occurs in the mouth or the crop. Enzymes contained
in pure intestinal juice have not been determined, but mixed intestinal
juice contains pancreatic juice and proteases in an alkaline medium.
The pH of the contents of digestive organs in the chicken is: crop, 4.5;
proventriculus, 4.4; gizzard, 2.6; duodenum, 5.7-6.01; jejunum, 5.8-5.9;
ileum, 6.3-6.4; rectum or colon, 6.3; cecum, 5.7. In live birds, the large
intestine was slightly alkaline (7.1). The acidity of avian bile (5.88 in
chickens) may, in part, account for the lower pH in the alimentary tract of birds
as compared to mammals. The secretion rate of bile in white Leghorn chickens is
about 1 milliter per hour, or about 9.5 milliter/kilogram of body weight per day.
The role of bile in avian digestion has not been fully studied, but it is presumed
that it aids in the absorption of fats by its emulsifying action and activating
effects on pancreatic lipases. Little fat is absorbed until the third segment
of small intestine is reached, where 42 to 60 percent (depending on type) is
absorbed. Most of the remaining fat (90 to 98 percent) is absorbed in the
fourth segment. Little fat is absorbed in the cecum or large intestine.
The liver has many functions other than its digestive action. There are
pronounced sex differences in blood levels of plasma proteins, lipids, and
calcium of birds. These differences are due primarily to the effect of the
female sex hormone on the liver in the formation and retention of these
substances. The clearance rate of liver, as measured by its ability to
extract sodium bromsulphthalein (BSP) from blood and excrete it in the bile,
is markedly influenced by estrogen and, as expected, the clearance rate is
greater in laying hens.
The development of an egg starts in the ovary, where the yolk portion is
formed. Here there are many ova, each enclosed in a follicle. The yolk is
deposited in concentric layers during growth and maturation, and these rings
may vary in color, depending on the amount of yellow pigment, or xanthophyll,
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in the food. When the process is complete, the follicle bursts and the yolk,
surrounded by a membrane, passes into the oviduct. This process may take from
7 to 10 days. As the yolk passes into the magnum, the albumin of the egg is
secreted around the ova. This process takes approximately 3 hours; then the
egg passes into the isthmus, where the inner and outer shell membranes are formed
in about an hour and a quarter, before the water is added through the semi-
permeable shell membrane to the albumin and where the egg shell is deposited.
The egg remains in the shell gland approximately 18 to 20 hours, then passes
to the vagina for laying (P. D. Sturkie's, 1970).
There are many problems inherent in the interpretation of the data derived
from studies of this nature. Not only do the hens vary in the length of time
they take to produce an egg, but the production of eggs is variable, with some
hens laying an egg a day for weeks while others lay sporadically. Thus, a
large range of activity can be anticipated in an egg laid at any given time
after ingestion of a radionuclide. Considering the above variables, the range
of the data shown in Table 1 would be expected.
TABLE 1. TRANSFER OF ORALLY ADMINISTERED AMERICIUM TO EGG YOLK
Total
Dose
(yci)
Time to
Peak
(days)
Peak Activity
Range
(pCi/18-g yolk)
Peak Activity
Average
(pCl/18-R yolk)
Half-time
(T% days)
Am 26.7 14 60-2,900 870 (1) 2.00±0.18
(2) >33
The transfer of americium to the egg yolks is presented in Figure 1. Each
point represents the average activity per yolk in eggs laid during that time
period. The americium activity increased over the dosing period with the maxi-
mum, 0.00326 percent of the total administered activity, occurring in eggs laid
after the fourteenth dose. Since no obvious plateau was evident, additional
doses might have resulted in a higher activity. The americium activity in the
egg yolks decreased with a half-time of 2.00 ± 0.18 days followed by a second
component of greater than 33 days. Americium was not detected in the white or
shell of the eggs, nor in any portion of the eggs from the control hens.
These results would appear to agree in general with published data on the
metabolism of iron. In an investigation to determine the metabolism of manga-
nese and iron by poultry (Panic, 1970), it was determined that measurable
quantities of iron-59 were found only in the egg yolk. An iron-59 concentra-
tion of 1.90 percent of the dose per yolk appeared in eggs laid 51 hours after
oral administration, with the peak concentration of 2.80 percent per yolk
occurring 6.1 days after initial ingestion. It was found that iron is trans-
ported from the blood to the yolk by a protein or proteins deposited in yolks
only. Furthermore, the iron is more firmly bound to the protein phosvitin
than to transferrin. Phosvitin appears in hen plasma during the laying
period and is deposited only in the yolk.
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Figure 1.
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Average concentration of americium-241 in egg yolks from chickens
ingesting 2 microcuries/day for 14 days
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Americium was absorbed by the hens with tissue concentrations occurring
mainly in the liver and skeleton (see Table 2). These results agree with
those of Taylor (1962) studying the metabolism of americium in rats.
In previous studies conducted with plutonium, it was found that chickens
absorbed a very small percentage of plutonium-238 ingested as the relatively
insoluble dioxide. This small percentage of absorption and transfer to egg
yolk appears to present little hazard to humans consuming the eggs. Laying
hens absorbed a somewhat higher percentage of the nuclide after ingesting a
more soluble form of plutonium-238 than that absorbed from ingestion of the
dioxide-form. Also, a large percentage of the absorbed plutonium was trans-
ferred to the yolk of the eggs. In older laying hens ingesting either form
of plutonium-238, plutonium does not appear to concentrate in tissue in
amounts large enough to constitute a hazard when human consumption is limited
to normal quantities. This may not be true of the livers of younger poultry
raised solely for food although little hazard could be expected.
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TABLE 2. ACTIVITY IN TISSUE FROM CHICKENS INGESTING 2 yCi AMERICIUM-241
CITRATE EACH DAY FOR 14 DAYS (AVERAGE AND STANDARD DEVIATION)
Tissue
Gizzard
w/o lining
Liver
Gall Bladder
w/bile
Heart
Muscle
Fat
Long bone
Sternum
Rib
Blood
Days After
Final Ingestion
1 (6)*
10 (7)
20(7)
1
10
20
1
10
20
1
10
20
1
10
20
1
10
20
1
10
20
1
10
20
1
10
20
1
10
20
% Dose/g
9-08 2.96X10"!?
8.67 4.45X10
2.48 1.71X10
3.36 3.11X10";!
8.00 2.28X10 ,
7.47 8.58X10
4.27 2.21X10"^
6.53 9.28X10
6.85 2.60X10
4.27 0.76X10"*?
8.73 8.67X10~£
5.68 3.80X10
1O Q A C f\ YT f\
. /.O U * j UA.JLU —
7.01 3.80X10~.L
6.59 2.29X10
3.23 3.02X10"!?
3.53 1.43X10 ;
2.63 2.69X10
1.94 1.15X10":?
8.35 6.26X10 J?
4.19 5.47X10
7.49 2.74X10"^?
1.26 0.76X10":*
6.42 6.93X10
8.80 4.27X10"^?
1.98 2.55X10 ,
5.77 5.63X10
7.00 5.39X10"^
4.19 5.43X10"^
1.05 0.46X10
Mean Weight
Total Organ, g
24.9
21.7
21.6
41.9
37.9
42.4
2.6
2.0
1.0
8.4
6.6
6.2
% Dose/organ
2 . 26X10"'?
1.88X10
5.30X10
1.41X10";*
3.03X10 .
3.16X10
1.11X10"^
1.31X10 ,
7.20X10
3.58X10~^
5.76X10
3.55X10
*Number of samples.
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REFERENCES
Durbin, P. W. Uranium and Plutonium—Transplutonic Elements. H. C. Hodge,
J. N. Stannard, and J. B. Hursh, eds. Springer-Verlag, New York.
740 pp. 1973
Hamilton, J. G. "The metabolic properties of the fission products and
Actinide elements." Rev. Mod. Phys. _2lD:718. 1948
Lindenbaum, A. and M. W. Rosenthal. "Deposition patterns and toxicity of
plutonium and americium in liver." Health Phys. 22:597. 1972
Maynard, L. A. and J. K. Loosli. Animal Nutrition. McGraw Hill Book Co.,
Inc., New York. 449 pp. 1962
Mraz, F. R., P. L. Wright, J. M. Ferguson, and B. L. Anderson. "Fission
product metabolism in hens and transference to eggs." Health Phys.
JLO:777. 1964
Panic, B. "Manganese and iron metabolism studies in poultry and swine."
Mineral Studies With Isotopes in Domestic Animals. STI/PUB-293,
CONF-700966. 81 pp. 1970
Sturkie, P. D. Duke's Physiology of Domestic Animals, J. J. Swenson, ed.
Cornel University Press, Ithaca, New York. 526 pp. 1970
Taylor, D. M. "Some aspects of the comparative metabolism of plutonium
and americium in rats." Health Phys. 8.:673. 1962
Taylor, D. M. "Interactions between transuranium elements and the components
of cells and tissues." Health Phys. 22:575. 1972
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/3-76-058
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
DISTRIBUTION OF INGESTED AMERICIUM IN CHICKENS AND
TRANSPORT TO EGGS
5. REPORT DATE
May 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
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-LV
U.S. Environmental Protection Agency
P. 0. Box 15027
Las Vegas, NV 89114
10. PROGRAM ELEMENT NO.
1FA628
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Same as above
13. TYPE OF REPORT AND PERIOD COVERED
Final FY75
14. SPONSORING AGENCY CODE
EPA-ORD
Office of Health & Ecological
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The soluble citrate complex of americium-241 was orally administered to 20 white
Leghorn laying hens daily for 2 weeks. The yolks, whites, and shells from the
eggs were analyzed for their americium content. Yolk was the only egg fraction in
which radioactivity was observed. The americium-241 activity in yolks reached a
maximum on the 14th day of dosing. Biological half-times of 2.00 ± 0.18 days and
greater than 33 days were indicated by the average concentration values of
americium-241 in yolks laid after the maximum activity was reached. /
The hens were serially sacrificed at 1, 10, and 20 days after the final admini-
stration of americium-241. Tissue samples were collected and the americium
content determined in the edible portions and feathers of the hens. Americium
was detected in most tissues shortly after dosing; the main concentrations were
found in the liver and the skeleton. The highest concentration per organ (3.03 X
10~3 percent of the dose) occurred in the liver of the hens sacrificed 10 days
after final administration of americium-241.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Americium
'hickens
Itrates
Radioactive Isotopes
ladiation Dosage
Americium in Chickens
Citrate Complex
Distribution and Trans-
port
Exposure/Dose Assessment
06C
06R
07B
07C
07E
18B
8. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
17
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
691- 220-1976
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