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Important Notice: The Hanford Health Information Network (HHIN) closed in
May, 2000. HHIN Web pages are provided as archived information only, and
are not currently maintained. Information contained on the HHIN Web pages may be
out-of-date.
Current information is available through the
Hanford Community Health Project,
which is updated by the Agency for Toxic Substances and Disease Registry of the
U.S. Centers for Disease Control and Prevention.
A PUBLICATION OF THE
Hanford Health
Information Network |
Plutonium, Strontium, Cerium and Ruthenium
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For more than 40 years, the U. S. government produced plutonium for
nuclear weapons at the Hanford Site in south central Washington State. In 1986,
responding to citizen pressure, the U.S. Department of Energy made public hundreds of
previously restricted documents. Since then, much attention has focused on the very
large releases of iodine-131 as a possible cause of
thyroid disease. However, Hanford also
released other forms of radiation into the air and the Columbia River.
This report examines the releases of four
radionuclides to the air and the
potential health effects which might result from people being exposed to these
materials. The four radionuclides are: plutonium, strontium, cerium and ruthenium.
Other radionuclides were released to the Columbia River. A separate
HHIN publication
addresses the possible health effects of these radionuclides.
According to the Technical Steering Panel of the Hanford Environmental
Dose Reconstruction Project, the largest contributors to
dose from the air
pathway were
first, iodine-131, then cerium-144, plutonium-239, ruthenium-103, ruthenium-106, and
strontium-90. Dose is the amount of radiation absorbed by a person's body. There were
many other radioactive materials released into the air, as well, but these contributed less
to dose, according to the Technical Steering Panel.
The Hanford Environmental Dose
Reconstruction (HEDR) Project was
established to estimate what radiation dose people living near Hanford some time
between 1944 and 1992 might have received from releases of radioactive materials.
The Technical Steering Paned, which directed the study, completed its role in 1995.
The federal Centers for Disease Control and Prevention (CDC) is now working with
the HEDR Task Completion Working Group to continue public participation and to
assure completion of the remaining HEDR activities. When using information from this
and other studies, readers should keep in mind that research results depend on a
number of factors, such as the information available, and the methods and type of
analysis used.
What are the possible health problems from exposure to plutonium,
strontium, cerium and ruthenium? Most of the information on health effects from
these materials has come from studies of plutonium workers and research involving
animals. None of these studies contains information that relates to the specific situation
of those people who lived downwind from Hanford. While comparisons to the
Hanford situation are uncertain, the information in this report may help identify
potential health problems
which may have been caused or could be caused by exposure
to these radionuclides.
Radiation health scientists generally believe that any
dose of radiation,
however small, carries with it an increased risk of some adverse health effect, such as
cancer. This does not mean that everyone who receives an exposure will suffer an effect.
It means the risk of a radiation-induced health problem is increased. Even if a particular
effect does occur in an individual, it is not possible to determine, with current scientific
methods, that it was caused by radiation exposure.
History of Hanford's Hot Particles
Unlike iodine-131 - which was released as
a gas - plutonium, strontium, cerium and ruthenium became attached to particles of
rust or dust and were then released. There were two time periods in Hanford's
operation when there were major releases of radioactive particles:
From late 1944
through at least 1951, there were large releases of particles containing plutonium,
strontium and cerium.
From 1952 to 1954, there were large releases of particles
containing ruthenium.
Plutonium, Cerium and Strontium
Starting in 1944, Hanford produced plutonium for use in nuclear weapons.
Uranium fuel was partially transformed into plutonium inside the nuclear reactors
along the Columbia River. The irradiation of uranium not only created plutonium but
also created numerous other radioactive elements, including the
radionuclides of
cerium, strontium and ruthenium, which are the subject of this report. After
irradiation, the uranium fuel (now containing plutonium and the other radionuclides)
was transported several miles to the separations plants at the center of the Hanford Site.
It was here that the fuel was dissolved in nitric acid. After numerous chemical steps, the
plutonium was separated from the fuel and purified for use in nuclear weapons.
The process of separating the plutonium released pollution to the air and the
ground. This report focuses on the potential health effects from exposure to those
radionuclides that were released to the air on particles. These particles are called "hot"
because they were radioactive.
Plutonium, cerium and strontium were released to the air from the original
plutonium separations plants from late 1944 through at least 1951. In the fall of 1947,
monitoring equipment revealed radioactive particles on the ground surrounding the
stacks of the plutonium plants. The ventilation system in the radioactive processing
area was the source of the problem. The interior of the plants' ventilation system had
started to rust in places. Plutonium and the other radioactive materials attached to the
rust. Later, parts of the contaminated rust broke off and went up and out the stacks. The
sections inside the plants in which the operators worked had a separate ventilation
system that was not affected by the particle problem.
The particles contained plutonium, cerium and strontium. Other radioactive
materials were also present in at least some samples of the particles but in lower
concentrations. Most of the particle was rust or other non-radioactive material.
In January 1948, Hanford replaced the ventilation system. The number of
relatively large particles decreased, but smaller particles continued to escape. Hanford
scientists believed that the smaller particles had been released from the start of
plutonium separations in December 1944. In March 1948, Hanford documents reported
the release of as many as 100 million particles per month.
Because of their size and weight, many of the particles landed on the ground
within the Hanford Site boundaries. However, Hanford technicians detected some
particles as far away as Mullan Pass (now known as Lookout Pass) in Idaho; and
Spokane and Mt. Rainier in Washington. The concentrations of the particles at these
locations were "comparable" to those in Richland (Richland
is located about 25 miles
southeast of the separations plants).1
Hanford officials were concerned about possible health effects on workers
from hot particles.
They considered lung cancer (from the inhalation of particles) to be
the most serious health threat.
Hanford radiation protection officials imposed several work restrictions and
ordered that some workers be given filter masks. However, most workers, including
construction workers and security guards, were not issued filter masks. Hanford officials
considered the plutonium particle problem so serious in October 1948 that they stopped
separating plutonium for at least three days.2
It is uncertain how long the problem with the plutonium particles continued.
According to a U.S. Senate report, the last reference to the problem was at a meeting in
1951. Herbert M. Parker, Hanford's chief health physicist, said at the meeting: "The
particle problem still remains, in my opinion, a very serious health problem."3
Ruthenium
After World War II, a new type of chemical process was developed to recover
plutonium for use in nuclear weapons. An unintended effect of this process was that
flakes of material, including ruthenium, accumulated on the inside lining of the stack
at Hanford's Redox plant. "Redox" stood for "reduction-oxidation" and described the
kind of chemistry used to separate the plutonium. As in the case of plutonium particles,
the ruthenium built up within the process ventilation system, which was separate from
the building ventilation system.
The Redox plant began operations in 1952. Shortly afterward, technicians
discovered the ruthenium particle problem. Material containing ruthenium had
deposited on the inside of the stack. As the material built up on the stack lining, some of
it broke off in the form of flakes and was carried up and out the stack. Radiation surveys
found very large flakes, some several inches across, on the ground around the base of
the stack.
The largest reported release was in January 1954 when about 200
curies of
ruthenium were released. Hanford radiation technicians tracked the particles as far as
Spokane, Washington, about 150 miles to the northeast. In April 1954, airborne
radiation equipment tracked the particles as far as northeastern Montana.
Inhaling ruthenium particles posed a health danger. In addition, the
ruthenium particles posed a hazard if any of the large particles had fallen onto a
person's exposed skin.
Hanford Assessment Not Yet Completed
Since the release of the first 19,000 pages of Hanford historical documents in
1986, much has been learned. However, it is not enough to form a complete assessment
of the impact of the Hanford releases. This is especially true in the matter of Hanford's
particle problems. For example,
the HEDR Project
has not yet estimated doses from
the hot particle releases.
Possible Health Problems of Plutonium, Strontium, Cerium and Ruthenium
Keep the following points in mind when reading the sections on the
possible health problems of the selected
radionuclides:
Researchers have done a few
studies involving human exposure to plutonium, as well as several animal studies. For
cerium, ruthenium and strontium, the only data available are from animal studies.
Comparing the health effects on animals and on people exposed to radiation from
Hanford is problematic for three main reasons:
1. The life span of human beings is much longer than that of the animals
used in studies.
2. It is uncertain if humans are affected in the same way as animals.
3. Most of the animal studies involved exposure to very high levels of
radiation (equivalent to a human exposure of thousands of
rem). Hanford exposed
people to generally lower levels of radiation but over a long time.
This report provides information about each of the four radionuclides. The
same categories of information are presented for each:
- the possible health effects
- a general description of the
radionuclide
- the estimated amount released from
Hanford from 1944 to 1972
The dose estimates are cumulative for 1944-1992, whole body in rem
EDE
(effective dose equivalent). The release estimates are cumulative for 1944-1972. These
numbers are taken from the Hanford Environmental Dose Reconstruction draft reports
released in April 1994. Both the release and dose estimates for the four radionuclides are
not complete because: (1) the Hanford Environmental
Dose Reconstruction Project has not yet reconstructed the amount of the four
radionuclides released on particles; (2) the computer model used in the study did not
simulate the behavior of particles; and (3) the Dose Reconstruction Project has not yet
estimated doses from the hot
particle releases. This work is now underway.
The federal Centers for Disease Control and Prevention (CDC)
is now working with the HEDR Task Completion Working Group
to continue public participation and to assure completion of the
remaining HEDR activities.
its chemical form as released from Hanford's weapons plants
The chemical form of the radionuclide is very important in assessing how the
body might handle the material. The chemical form may significantly affect the dose a
person receives from incorporating the material into the body. One aspect of the
chemical form is whether it is soluble
or insoluble. The Hanford Environmental Dose
Reconstruction Project assumed that plutonium and cerium were released in soluble
forms.
the range of representative doses
The dose estimates are cumulative for 1944-1992, whole body in rem EDE
(effective dose equivalent).
a summary of health studies
Plutonium
Possible Health Effects: Bone, liver and lung cancer;
leukemia;
chromosome
aberrations
Description: The isotope of plutonium
for which the Dose Reconstruction
Project is calculating dose estimates is plutonium-239.
Estimated Amount Released from Hanford: 1.78
curies
Chemical Form of Release: Assumed to be
soluble4
Range of Representative Dose Estimates: 0.03
mrem
EDE to 3.6 mrem EDE
Summary of Scientific Studies
PLUTONIUM:
Cancer
Studies of plutonium workers and many animal studies have focused on
exposure to insoluble
forms of plutonium. The Hanford Environmental Dose
Reconstruction Project assumed that the plutonium released to the air was in a
soluble
form. The potential health problems of soluble and insoluble plutonium are described
below.
When plutonium is inhaled in an insoluble form, most of it that is retained
in the body remains in the respiratory tract. In this kind of exposure, cancers of the lung
are possible. Plutonium workers are usually exposed to the insoluble forms of
plutonium. Studies of these workers have not found an increased risk for lung cancer
that is related specifically to plutonium exposure.5 In animal studies, nearly all animals
that were exposed to high doses of insoluble plutonium died either of extensive lung
damage or lung cancer.
Most insoluble plutonium particles that are inhaled are removed from the
body within a few days. Some particles are removed via the lymph nodes. Some of these
particles may remain in the lymph nodes for years. In animal studies, high exposure
caused the lymph nodes to stop functioning properly. Dr. H. Metivier with the
Experimental Toxicology Laboratory in Montrouge, France, has suggested that
plutonium could weaken the immune system
in humans and lead to the development
of cancers outside of the lymph nodes.6
In 1987, a study of Rocky Flats workers by Dr. Gregg S. Wilkinson (then at the
Los Alamos National Laboratory) and others concluded that workers who had
plutonium inside their bodies had an increased risk of
lymphopoietic neoplasms
(tumors affecting a kind of white blood cells).7 A report by the Committee on the
Biological Effects of Ionizing Radiations of the National Research Council (BEIR IV) was
skeptical about this finding because the Rocky Flats study did not show any increases in
lung, bone or liver cancers.8
Plutonium in a soluble form acts differently in the body than the insoluble
form. Instead of remaining in the lungs and the lymph nodes, as the insoluble form
does, soluble plutonium enters the blood relatively quickly and deposits on bone
surfaces and in the liver. About 40 percent of the plutonium that enters the blood goes
to bone surfaces, 40 percent to the liver and the remaining 20 percent to muscle.9 If a
person is exposed to soluble plutonium, cancers of the bone and liver are possible, with
the likelihood dependent on the dose.
Some scientists stress the need for additional studies on humans because of
the long time lapse between exposure and when cancers are diagnosed. This period is
called the latency period. For plutonium, the latency period is estimated to be more than
30 years, but may vary depending on the dose received.10
PLUTONIUM:
Leukemia
There are conflicting opinions in two studies regarding plutonium exposure
and the risk of leukemia. Leukemia is a cancer of the blood and begins in the blood cells
formed within the bone. Metivier stated at a symposium presented by the French
Society of Biophysics and Nuclear Medicine in 1982 that there is a possibility of
leukemia if the bone marrow is exposed to plutonium.
11 However, the 1988
BEIR IV report stated there is no evidence that plutonium can cause
leukemia.12 In humans,
relatively little plutonium is found in the bone marrow, and the dose to this tissue is
quite small compared to the dose to the bone surfaces. The risk of leukemia from
exposure to plutonium is likely to be far less than the risk of bone cancer.
PLUTONIUM:
Chromosome Aberrations
E. Janet Tawn and her colleagues in the Medical Department at British
Nuclear Fuels, Sellafield, England, did a study of the
chromosomes of 54 plutonium
workers who were exposed to plutonium mainly by inhalation. Each plutonium worker
had a higher number of chromosome aberrations compared with workers not exposed
to plutonium. The scientists concluded that the exposure to plutonium increased the
number of aberrations.13
Strontium
Possible Health Effects: Leukemia,
bone cancer, weakened immune system
Description: The isotope
of strontium for which the Dose Reconstruction
Project is calculating dose
estimates is strontium-90. In the body, strontium is
chemically similar to calcium. Therefore, the body is likely to use strontium in the same
way it would use calcium.
Estimated Amount Released from Hanford: 64.3
curies
Chemical Form of Release: unknown
Range of Representative Dose Estimates: 0.0007
mrem
EDE to 0.07 mrem EDE
Summary of Scientific Studies
STRONTIUM
Leukemia
Strontium may cause leukemia.
14 More than 90 percent of the strontium that
remains in the body is in the bones.15
According to M. Thomasset, MD, Director of Research at the National Center
of Scientific Research, National Institute for Health and Medical Research, Le
Vesinet,
France, "continuous low doses" of strontium cause relatively more cases of leukemia
than high, one-time doses.16
STRONTIUM
Cancer
Because strontium deposits in the bones, bone cancer is also a possible
health
effect. Animal studies have shown that high doses
of strontium produce a relatively
large number of bone cancers. At lower levels of exposure, there are very few cases or
none. A Utah study conducted on beagles did not find bone cancers at low doses.17
STRONTIUM
Immune System
Thomasset reported that continuous low doses
of strontium weakened the
immune system for up to one year after the exposure.18
Cerium
Possible Health Effects: Leukemia;
and bone, liver, and nasal cavity cancers
Description: The isotope
of cerium for which the Dose Reconstruction Project
is calculating dose estimates is cerium-144.
Estimated Amount Released from Hanford: 3,770
curies
Chemical Form of Release: Assumed to be
soluble19
Range of Representative Dose Estimates: 0.05 mrem
EDE to 5.4 mrem EDE
Summary of Scientific Studies
CERIUM
Cancer
All of the information on cerium's health
effects comes from animal studies.
Cerium concentrates in the bone marrow. Because of this, the risk of
leukemia is the
predominant potential health problem.
When insoluble cerium
is inhaled, it remains in the lung. When soluble
forms are inhaled, cerium moves into the bones and liver. Bone and liver cancers, as
well as liver damage, are possible. The National Council on Radiation Protection has
stated that cancers of the nasal cavity are also possible.20
Ruthenium
Possible Health Effects: Cancer, skin burns
Description: There are two isotopes
of ruthenium for which the Dose
Reconstruction Project is calculating dose
estimates: ruthenium-103 and
ruthenium-106.
Estimated Amount Released from Hanford:
ruthenium-103: 1,160 curies
ruthenium-106: 388 curies
Chemical Form of Release: unknown
Range of Representative Dose
Estimates: 0.009 mrem
EDE to 0.89 mrem EDE
Summary of Scientific Studies
RUTHENIUM
Cancer
Very little information is available on the potential for ruthenium to induce
cancers. One study that considered the possible
health effects from ruthenium did not
distinguish between ruthenium-103 and ruthenium-106. In animals exposed to
ruthenium, cancers did develop. However, a report on the study by R. Masse, a
veterinarian and Chief of the Experimental Toxicology Laboratory in Montrouge,
France, did not specify where in the body the cancers developed.21
RUTHENIUM Skin Burns
Ruthenium particles released from Hanford posed a hazard if any of the
particles had fallen onto a person's exposed skin. This could have caused skin burns.
downwinder perspective
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Many callers to the Hanford Health Information Lines have
questions and concerns about the release of plutonium and other radioactive materials
from Hanford. Some downwinders
have health problems and believe that they are, or
might be, related to Hanford. The following personal perspective is offered to help
readers understand these experiences and concerns.
"My father worked at Hanford as an ironworker/rigger, heavy equipment
operator and supervisor from 1947 until his death from lung cancer in 1985. He was 60
years old when he died. Thirty-four of his years at Hanford were spent in the 200 Areas
(where the plutonium was processed and separated). He and his crew buried
contaminated dry waste such as lab equipment or, in some cases, even trucks and cranes
in the ground. He helped to construct the tank farms and was involved in the transfer
of liquid wastes to the underground tanks.
"Dad was aware of the problems with the stacks and release of plutonium
particles onto the ground and he worried because his crew was there.
"Years later, in 1974, dad discovered that the Hanford doctors had for four
years withheld evidence that he had scarring in his lungs. During his annual medical
checkup, a new doctor mentioned that the scarring in his lungs was getting worse. He
asked the doctor, 'What scarring?' Being concerned about getting proper medical care,
dad went to Seattle for another exam. After a thorough work-up at the Virginia Mason
Clinic, he was diagnosed with 'silicosis, caused by particles in the lungs.' His condition
continued to deteriorate, eventually becoming lung cancer.
"I can't help but wonder, what were those particles? Were they
'hot' particles
released from the stacks at Hanford decades earlier? Were they just sand? And why did
the Hanford doctors, year after year for four years, withhold my dad's
medical condition from him?"
This perspective was contributed by a woman
whose father worked at Hanford. She was born in 1948 in Richland and lived there
until 1966. She recalls that much of her family's milk and vegetables came from her
uncle's farm in Kennewick. Name withheld by request.
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Unresolved Issues Concerning Hanford's Hot Particles
During the preparation of this report, the technical
reviewers raised several
important points that should be included.
Karl Z. Morgan, Ph.D., expressed great skepticism with the estimate for the
amount of plutonium released from Hanford. The current estimate from the Hanford
Environmental Dose Reconstruction Project is 1.78
curies of plutonium released to the
air. Based upon his experience at the Oak Ridge (Tennessee) nuclear weapons facility
and his knowledge of Hanford processes, Morgan believes that the current estimate is "a
gross underestimate." Morgan is regarded by many as the father of health physics and
was chief of radiation protection at Oak Ridge. He was chairman of the Internal Dose
Committees of both the International Commission on Radiological Protection (ICRP)
and the National Committee for Radiation Protection (NCRP) from 1949 to 1971. These
committees set the maximum permissible radiation exposure limits on the
international and national level, respectively.
Professor Ronald L. Kathren felt it was important to state that, given the
current low radiation dose
estimates from the selected radionuclides, it is "extremely
unlikely" that there will be any measurable health problems among those exposed to
Hanford's radiation releases. "Measurable health problem" means an effect that could
be determined by an epidemiological
study as being related to exposure from Hanford's
radiation. Kathren is the director of the United
States Transuranium and Uranium
Registries and a professor at Washington State University.
Tim Connor stated that the assumption by the Hanford Environmental Dose
Reconstruction Project that all of the plutonium released by Hanford to the air was in a
soluble
form is tenuous at best. Connor is concerned that even if the plutonium
separated at Hanford was initially dissolved by nitric acid, further steps in the separation
process would have resulted in transforming at least some of the soluble plutonium to
an insoluble
form. Thus, a considerable fraction of plutonium escaping to the
atmosphere may have been in an insoluble form. Connor is a researcher with the
Energy Research Foundation in South Carolina and was a staff member of the Hanford
Education Action League (HEAL) for several years.
Summary
While comparisons to specific individuals are often uncertain, the
information in this report may help identify potential health problems from exposure
to Hanford's releases of plutonium, cerium, strontium and ruthenium. An important
point to recall is that the estimates of the amounts released and the
doses received are
not yet complete.
The Technical Steering Panel completed its role in 1995. The federal Centers
for Disease Control and Prevention (CDC) is now working with the HEDR Task
Completion Working Group to continue public participation and to assure
completion of the remaining HEDR activities.
References for the History of Hanford's Hot Particles
Stohr, Joe. Memo to the Technical Steering Panel and the Centers for Disease
Control: "Preliminary Review of Documents Describing Hanford Particulate Releases,
1944-1954." December 26, 1990.
Thomas, Jim. Hanford Education Action League (HEAL) Memo to the
Technical Steering Panel: "Request for Independent Calculations on the Active Particle
Problem." April 20, 1992.
Till, John, Ph.D., and Charles Miller, Ph.D. Memo to the Technical Steering
Panel: "Active Particle Problem at Hanford." Undated.
U.S. Senate, Majority Staff of the
Committee on Governmental Affairs. "Early Health Problems of the U.S. Nuclear
Weapons Industry and Their Implications for Today." December 1989.
NOTES
1 - HW-11348. "Action Taken with Respect to Apparent Enhanced
Active Particle Hazard." H.M. Parker. October 25, 1948; p.2.
2 - HW-11348, p.2.
3 - "Early Health Problems of the U.S. Nuclear Weapons Industry and Their
Implications for Today." Report of the Majority Staff of the Committee on
Governmental Affairs, U.S. Senate, December 1989; p. 9 - Referring to meeting notes
from the Advisory Committee for Biology and Medicine, Jan. 12, 1951.
4 - Telephone conversation with Bruce Napier, June 13, 1994. Napier is a
scientist with Battelle Pacific Northwest Laboratory and worked extensively on the
Hanford Environmental Dose Reconstruction Project.
5 - There have been human plutonium studies by several groups of
researchers. Three of these are: George L. Voelz, Occupational Medicine Group, Los
Alamos National Laboratory, et al. who studied 26 Manhattan Project workers at Los
Alamos with 37-year follow-up after exposure (Voelz 1985); J. F. Acquavella et al. who
also considered Los Alamos workers (Acquavella 1983); and Gregg S. Wilkinson et al.
who studied Rocky Flats workers (Wilkinson 1987)
6 - H. Metivier in Radionuclide Metabolism and Toxicity; Galle, P. and R.
Masse (eds.); Paris: Masson, 1982; p. 184. The book is a compilation of papers presented at
a 1982 symposium that was organized by the French Society of Biophysics and Nuclear
Medicine and the University of Paris.
7 - Gregg Wilkinson, Ph.D. "Mortality Among Plutonium and Other
Radiation Workers at a Plutonium Weapons Facility." American Journal of
Epidemiology. 1987; p. 231-250.
8 - Committee on the Biological Effects of Ionizing Radiations (BEIR IV);
Health Risks of Radon and Other Internally Deposited Alpha-Emitters; Washington,
DC: National Academy Press, 1988; p. 328.
9 - Telephone conversation with Prof. Ronald Kathren, U.S. Uranium and
Transuranium Registries, July 22, 1994..
10 - George L. Voelz, MD. "Health Considerations for Workers Exposed to
Plutonium." Occupational Medicine: State of the Art Reviews. Oct-Dec 1991; p. 694.
11 - H. Metivier in Galle and Masse, p. 193.
12 - BEIR IV, p. 325.
13 - Tawn, E.J. et al. "Chromosome Studies in Plutonium Workers."
International Journal on Radiation Biology and Related Studies in Physics, Chemistry
and Medicine, May 1985; p. 599-610.
14 - M.C. Thorne and J. Vennart; "The Toxicity of Sr-90, Ra-226 and Pu-239."
Nature; October 14, 1976; p. 555-8. Thorne is with the Radiobiology Unit in Hardwell,
England.
15 - M. Thomasset. "Strontium: Metabolism and Toxicity of Strontium" in
Galle and Masse, p. 104.
16 - M. Thomasset in Galle and Masse, p. 111.
17 - National Committee on Radiation Protection (NCRP) No. 110; Some
Aspects of Strontium Radiobiology; 1991; p. 32.
18 - M. Thomasset. "Strontium: Metabolism and Toxicity of Strontium" in
Galle and Masse, p. 110.
19 - Telephone conversation with Bruce Napier, June 13, 1994.
20 - National Committee on Radiation Protection (NCRP) No. 60; Physical,
Chemical, and Biological Properties of Radiocerium Relevant to Radiation Protection
Guidelines; 1978; p. 55.
21 - R. Masse, "Ruthenium and Activated Metals" in Galle and Masse, p.
131-142.
References for Selected Radionuclides
Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological
Profile for Plutonium, TP-90-21. December 1990.
Galle, P. and R. Masse, eds.
Radionuclide, Metabolism and Toxicity. Paris: Masson, 1982.
NCRP Report No. 60. Physical, Chemical, and Biological Properties of
Radiocerium Relevant to Radiation Protection Guidelines. Washington, DC: National
Council on Radiation Protection and Measurements, 1978.
NCRP Report No. 110. Some Aspects of Strontium Radiobiology. Bethesda,
MD: National Council on Radiation Protection and Measurements, 1991.
Published Fall 1994
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