EPA 680/0-74-002
July 1974
PULMONARY CARCINOGENIC EFFECTS OF PLUTONIUM-238
PARTICLES IMPLANTED IN THE LUNGS OF HAMSTERS
by
A. A. Mullen
Monitoring Systems Research and Development Laboratory
National Environmental Research Center
Las Vegas, Nevada
Program Element 1FA082
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 89114
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PULMONARY CARCINOGENIC EFFECTS
OF PLUTONIUM- 238 PARTICLES
IMPLANTED IN THE LUNGS OF HAMSTERS
ROAP: 21EAL
Plumonary Carcinogenic Effects of Radioactive Particles
Task "003: INTERIM REPORT
Periodic serial sacrifice, histological examination of selected
tissues, dosimetry
I. CONCLUSIONS .---' -
Inference of conclusions for this study is premature because of the
limited number of observations to date.
Ten months after implantation of single microspheres containing
plutonium-238 in the lung's of 900 Syrian hamsters, 400 animals have been
necropsied and the remaining 500 are still alive. Aproximately 11,000
slides representing 268 -of the animals have been prepared for histopatho-
logical examination. Half -of these have been reserved as duplicates for
later study, if required. To date, the lungs of 31 animals have been examined
for histopathology by the pathologist. '
: No gross lung lesions were observed in any animals necropsied during
the first eight months. However, at nine months, lung lesions were observed
in animals from all experimental groups (I- IV), but not in the controls (V-VI).
II. RECOMMENDATION
Completion of the project with additional assistance for histological
slide preparation is recommended.
III. INTRODUCTION . ,
This ROAP was developed to meet Agency needs in evaluating the environ-
mental impact of nuclear power programs, principally in the areas of fast
breeder reactors for the production of plutonium fuel, in nuclear fuel reprocess-
ing plants, in nuclear fuel fabrication facilities, and in localities where
plutonium has been released to the environment during past activities (e.g.,
Nevada Test Site and Rocky Flats). Plutonium is discharged in liquid and
gaseous wastes from fuel reprocessing and has been measured in off-site air
samples (Need 02ADK, 15 Oct 72). Of concern are the inhalation of particles
from the discharge plume as well as inhalation of resuspended particles
previously deposited. Present standards for plutonium are based on the
assumption that inhaled plutonium is uniformly distributed throughout the
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lungt however, it is well-known that inhaled particles will not be uniformly
distributed, and that the resulting localized areas-of intense radiation may
present a greater hazard. This study will aid in determining whether current
standards are adequate for this type of exposure and to determine a realistic
definition of the non-uniformity factor for alpha radiation from particles
deposited in the lung..
IV. .OBJECTIVES AND APPROACH! . . '
The objectives'of this study were as follows: -
1. Determine in animals the carcinogenic potential of radioactive par-
ticles deposited in the lung, with special attention to dose/response, latent
period for cancer induction, and sequential precancerous changes.
2. Evaluate the role of-non-uniform, distribution of dose on the carcin-
ogenic response. :_.;.':.....
3. After the introduction of plutoniura, determine the RBE for plutonium
alpha as compared-to fission product inventory betas for the production of
primary lung tumors in animals.
The animal selected.for:this initial study was the Syrian hamster, an
animal which is relatively free from the chronic respiratory diseases of
other rodents and is reported to have a dose-response similar to man with
respect to cancer types induced following inhalation of known carcinogens.
A simple, relatively atraumatic technique for implanting a single radio-
active particle in the lung of rodents was developed for this project by
Stanley and Lloyd (1972). A small polyethylene cannula introduced into the
trachea of an anesthetized rodent provided the passageway for the insertion
into the deep lung of a fine catheter containing a radioactive particle.
The particles used in this study were silicate glass microspheres
produced by the Monsanto Research Corporation, Mound Laboratory, Miamisburg,
Ohio. The microspheres (100 + 20 urn, CMD) contain specified amounts of
plutonium oxide along with 1 nCi of a gamma emitting tracer ( Na). The
technique used to manufacture the microspheres is fully described in the
paper by Jones et al. 0-964),
Six groups of 150 Syrian hamsters (Mesocricetus auratus) each were used
for this study. Animal groupings and measured particle activities are described
in the following table. .
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Immediately following sacrifice or death, each animal is necropsied and
a detailed description of all gross observations is recorded. Although
several other tissues are routinely collected, the lung is the tissue of
principal interest. The lobe containing the particle, as ascertained by
visual identification of necrotic lesions or by gamma counting, .is immediately
fixed in formalin. .
Each lung lobe containing a particle is dehydrated and imbedded in
paraffin so that the convex surface will be tangential to the microtome knife
when sectioning begins. Each" lobe is completely sectioned at five micro-
meters and at each 100 micrometer interval, two adjacent pairs of sections
are mounted on two slid'es. One of these is stained with Hematoxylin and
Eosin for examination by the contract pathologist and the other is reserved for
later study, if needed.
V. PRELIMINARY RESULTS
Nine months after particle implantation, 500 of the original 900 animals
are still alive. Four hundred animals have been necropsied and the lungs of
268 of these have been sent to the pathologist (or a total of approximately
5,500 slides). Results from 31 of these animals have been returned. In
general, the gross pathology may be summarized as follows: No gross lesions
were observed in the lungs of any animals examined during the first eight
months after particle implantation. At nine months necrotic areas less than
1 mm in diameter were observed in lungs.from animals in the first four experi-
mental groups. No gross differences were observed between dose groups.
No lesions were observed in the control groups. .In a previous study, using
implanted beta emitting particles, necrotic areas from 1 mm to 3 mm in diameter
were seen two weeks-after particle implantation. _
Histologically, of the 31 animals examined, all animals except nine exhibited
focal pleuritis, a characteristic reaction to the radioactive implant. This
lesion was characteristically the same in each animal and varied significantly
only in degree. The morphologic appearance consisted of a cavity (most likely
the exact site of particle placement) approximately 100 micrometers in diameter
surrounded by an. area of inflammatory reaction. This cavity was surrounded by
chronic reactive cells, most of which were plasma cells and lymphocytes, and
mild connective tissue proliferation. In cases where the lesion closely
approximated the pleural surface, excess fibrous tissue extending from the
pleural membrane was found. Free hemosiderin and phagocytized hemosiderin
particles in large macrophages were .seen in most cases. Mild proliferation
of alveolar epithelium adjacent to the lesion was frequently observed but no
adenomatoid responses like those in the previous "hot" particle study, using
beta emitters, was observed.
VI. DISCUSSION
No firm conclusions can be drawn at this time because of the limited
number of observations.
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TABLE SHOWING ANIMAL GROUPS AND PHYSICAL PARAMETERS OF IMPLANTED PARTICLES
Radioactivity
Group
22
Treatment
Na Tracer
(nCi)
238
Pu
Alpha p.adiation at
particle Surface
II
III
IV
Single radioactive
Particle
Single radioactive
. Particle
Single radioactive
Particle
Single radioactive
Particle
Inert particle
with gamma tracer
47 + 7
90 + 13
348 + 26
649+54
VI
Environmental control
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VII. REFERENCES
Ceraber, H., J. A. Watson, and A. S. Spritzer. (1955) "Bronchogenic
Radioactive Cerium Fluoride." A. M. A. Archives of Industrial
Health 19. 14-23.
Chevalier, H. H., Łt_ al. (1971) "Sur Formalen Genese der Pseudoadenoraatose
der Lunge bein Syrschen Goldhamster."' Z. Versuchstierk 13, 38-50.
Feron, V. (1972) "Respiratory Tumors in Hamsters After Intratracheal
Instillation of Benzopyrene Alone and With Furfural." Cane. Res.
_32_, 28-36.
Gross, P., et_ al.. (1965) "Experimental Lung Cancer in Hamsters."
Arch. Environ. Health 11, 59..
Homburger, P. (1969) "Chemical Carcinogenesis in the Golden Syrian
Hamster, A Review." Cancer 23, 313.
Jones, L. V., Łt a_l. (1964) "Plutonium-Bearing Glass for Nuclear
Applications." Am. Ceramic Society Bull. 43, 131-135.
Kotrappa, P. (1974) "Hazards of Airborne Particulates." Scavenger 4, 3-6.
(Published in Bombay, India).
Mikhail, S. Z. (1970) Tissue Beta Radiation Doses From Particulate Fission
Product Sources, Environmental Science Associates, ESA-TR-70-01. .
Spencer, L. V. (1960) National Bureau of Standards Monograph One.
Stanley, R. E. and S. R. Lloyd. (1972) "A Technic for Implanting a
Radioactive Particle in a Rodent Lung." Lab. Animal Sci.,
2J2, 424-427.
Ulverg, J. C. and D. B. Kochendorfer. (1966) Models for Estimating
Beta Dose to Tissue From Particle Debris in Aerospace Nuclear
Applications, U.S.N.R.D.L.-TR-1107.
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