HERE YOU'LL FIND... |
History of Hanford's Hot Particles |
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.
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.
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.
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.
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
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.
Keep the following points in mind when reading the sections on the possible health problems of the selected radionuclides:
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.
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).
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.
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
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 |
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. |
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.
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.