HANFORD DOWNWINDERS INFORMATION SITE
The Immune System and
Radiation

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Radiation Doses from Hanford

Immune System

High-Dose Radiation

Low-Dose Radiation

Hanford Radiation and the Immune System

Release of Radioactive Materials from Hanford

Downwinder Perspective

Summary

This publication offers an introduction to the possible connections between radiation exposure and effects on the immune system. It begins with a brief overview of radiation doses from Hanford and a description of the immune system and its functions.

In some sections, this publication discusses studies on the health risks associated with radiation at or above a certain dose. However, any exposure to radiation poses a health risk. This is the basic assumption of radiation protection standards. When reading about these studies, one should keep in mind that health risks may exist below the doses discussed.

Some people believe that there is a higher-than-usual rate of immune system diseases among individuals exposed to the releases of radioactive materials from Hanford. This is discussed later in this publication.

Other Hanford Health Information Network publications provide more detailed discussions about other potential radiation health effects. (See also, Selected Radionuclides and Radionuclides in the Columbia River, Radiation and Cancer, Genetic Effects.)

Radiation Doses from Hanford

People living in the Hanford region were exposed to radioactive substances over many years. The radiation dose a person received depends on a number of factors, including the years over which exposure occurred; age at exposure; the amount of contaminated food and water consumed; the distance and direction lived from Hanford; and the length of time lived there.

Most studies of radiation health effects have been of people who received high doses over a short time from external radiation sources. The risks from these single, high doses may not be the same as the risks from lower doses over a long time. For this reason, it may not be possible to draw conclusions about the effects of low doses from high-dose studies. The situation of people exposed to radioactive materials released from Hanford is different from other exposed populations that have been studied.

This publication discusses the possible connections between radiation exposure and effects on the immune system.

IMMUNE SYSTEM

The immune system is a complex network that helps fight diseases and foreign substances. The most important cells in the immune system are lymphocytes which are a type of white blood cell. Of the cells of the immune system, lymphocytes are the most susceptible to radiation.

The immune system helps fight infectious diseases, such as pneumonia and chicken pox. When the immune system is not working properly, serious illness can result from immune system disorders or autoimmune diseases.

Immune system disorders include allergic reactions and disruption of the immune surveillance system. The prime function of this system is to detect and eliminate cells and molecules foreign to the body.

In autoimmune diseases, the immune system is no longer able to distinguish between the body's own cells and foreign cells, such as germs. This inability to distinguish between "self" and "non-self" results in an immune system response directed at the person's own tissues. This is called an autoimmune response. Rheumatoid arthritis, Graves' disease, Hashimoto's thyroiditis, insulin-dependent diabetes, some blood disorders, and multiple sclerosis are examples of autoimmune disease.

The immune system may be impaired at birth or during a person's lifetime. It may be weakened by such things as malnutrition, treatment with X-rays or drugs used to treat cancer. When the immune system is disrupted, a person is more susceptible to infection, and sometimes to autoimmune disorders and some cancers, such as multiple myeloma.

Is there any connection between a person's exposure to radiation in the environment and effects on the immune system? Studies attempting to answer this question typically address the effects of either high- dose or low-dose radiation.

HIGH-DOSE RADIATION

Researchers know more about how high-dose radiation affects the immune system than about whether and how low-dose radiation affects it. High-dose radiation can be defined as any exposure above 50 rad to the whole body. Such exposures often occur over a short time. Information about the high-dose radiation effects on humans comes mostly from studies of Japanese atomic bomb victims, radiation accidents and medical uses of radiation.

The effects of radiation on the immune system generally intensify with the amount of dose received. Massive cell death, inflammation and infection are the acute effects of high-dose radiation exposure. The number of lymphocytes declines within the first 12 to 48 hours after exposure. This is followed over several weeks by a decline in the number of other blood cells. The decline in lymphocytes is one of the best early signs of the severity of the radiation injury. During this period of decline, fevers, infections and bleeding can result in death. In those who survive, the time for recovery of the immune system varies depending on the level of exposure. The immune system usually recovers within a couple of months.

Death always occurs at whole-body radiation doses above 1500 rad. Despite supportive medical treatment, death is probable at whole-body doses between 500 and 1500 rad without a bone marrow transplant. Most people survive whole-body doses between 200 and 400 rad, particularly with supportive care. Whole-body doses below 200 rad generally cause a moderate decrease of white cells and mild intestinal symptoms, including nausea and vomiting.

Medical researchers have studied the use of high-dose radiation in treating diseases. Radiation treatments are used to kill cancer cells. High doses of whole-body radiation are often used as part of a patient's preparation for a bone-marrow transplant. This whole-body radiation lowers both the number and function of lymphocytes, as well as other types of white blood cells. Partial body exposures cause less serious effects. The higher the dose, the greater the decrease in cells.

Since lymphocytes are particularly active against bacteria and viruses, patients who receive whole-body radiation treatments are more susceptible to infections. There is a short-term increase in the risk of bacterial and viral infections. With either whole-body or partial body exposures, high-dose radiation treatments may lower lymphocyte levels for several years. During this period of time, there is an increase in the risk of shingles, which is caused by the chicken pox virus.

There is some information to suggest that the age of a person at the time of exposure also affects radiation sensitivity. Certain people, such as infants, young children and the elderly, tend to be at greater risk for health effects from radiation exposure. Lymphocytes in newborns are the most sensitive to radiation. Current studies are trying to define why certain cells in the immune system are more sensitive than other cells and what aspect of their function is affected. The results of these studies may be of interest to people exposed to Hanford's radioactive releases.

LOW-DOSE RADIATION

Researchers know less about the effects of low-dose radiation on the immune system than about the effects of high-dose radiation. Low doses can be defined as those less than 50 rad to the whole body.

Low-dose radiation has been shown to cause mutations and chromosome aberrations in the lymphocytes of children and adults. Researchers do not know how this information relates to the overall health of the immune system.

Low doses can cause leukemia, a cancer of cells in the immune system. Leukemia is currently the only blood system disorder clearly related to low-dose exposures. Dr. Alice Stewart and others found an increased risk of leukemia in children exposed to X-rays while in the womb. There is currently no medical evidence that cell mutations in exposed persons will cause immune system diseases.

Autoimmune Thyroid Disease

In 1994, a team of Japanese scientists reported finding an increased risk for autoimmune hypothyroidism among people exposed during the atomic bombing of Nagasaki in World War II.1 This study did not include the survivors of the Hiroshima bombing. Apparently, this is the first report of detecting a significant increase in an autoimmune disease among people who survived the atomic bombings.

The authors pointed out that the doses assigned to the study participants did not account for any internal exposure from bomb fallout, just the external dose from the bomb blast. There is no information to calculate internal doses from fallout. By contrast, radiation exposure from Hanford was generally low-level and nearly all of the dose was internal. The Hanford Thyroid Disease Study is including an assessment of autoimmune thyroid disease in its study.

An earlier article reported on a pilot study of autoimmune thyroid disease among women who had been previously treated with X-rays for tuberculosis.2 Michael M. Kaplan and his colleagues found a higher rate of autoimmune thyroid disease among those exposed compared with a control group who had not been exposed. This small study considered both Hashimoto's thyroiditis and Graves' disease. Although the women were exposed to X-rays (rather than iodine-131), the article did point out that average doses ranged between 11 and 112 rad to the thyroid and were delivered over several years.

Release of Radioactive Materials from Hanford

The U.S. government chose the Hanford Site in 1943 to produce plutonium for use in nuclear weapons. The process of creating plutonium continued at Hanford for more than 40 years. Throughout this era, Hanford operations released radioactive materials that contaminated the air, soil, groundwater and the Columbia River.

In 1986, responding to public pressure and requests under the Freedom of Information Act, the U.S. Department of Energy released 19,000 pages of previously secret or inaccessible documents. Until then, few people knew about the radioactive releases. The documents created widespread interest and concern. Studies of the health and environmental effects soon followed. One such study is the Hanford Environmental Dose Reconstruction Project.

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 Panel, 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 the Dose Reconstruction Project 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.

Air releases: Hanford released many radioactive materials into the air. Most of these emissions occurred during the separation of plutonium from the nuclear reactor fuel. The Dose Reconstruction Project estimates that the iodine-131 released was the major contributor to radiation dose. Dose is the amount of radiation absorbed by the body. The Dose Reconstruction Project considers iodine-131 to represent the greatest health threat from Hanford's past operations. From 1944 to 1972, Hanford released an estimated 739,000 curies of iodine-131 into the air. For comparison, the 1979 accident at Pennsylvania's Three-Mile Island reactor released an estimated 15 curies of iodine-131.

The Hanford Environmental Dose Reconstruction Project has estimated radiation doses from the following radioactive materials released into the air: iodine-131, ruthenium-103, ruthenium-106, plutonium-239, strontium-90 and cerium-144.

River releases: From 1944 to 1971, Hanford released other radioactive materials into the Columbia River through river water used to cool the reactors. The major river releases occurred between 1955 and 1964. The Hanford Environmental Dose Reconstruction Project is estimating doses from the following radioactive materials released into the river: arsenic-76, sodium-24, neptunium-239, phosphorus-32 and zinc-65.

Soil contamination: Hanford operations dumped billions of gallons of radioactive water into trenches and surface ponds. This radioactive water then seeped through the soil and into the groundwater. The Dose Reconstruction Project believes there was little direct human contact with the contaminated groundwater in the past.

HANFORD RADIATION AND THE IMMUNE SYSTEM

Some people believe that there is a higher-than-usual rate of immune system diseases, particularly autoimmune diseases, among people exposed to Hanford's releases. These people believe there is a link between radiation from Hanford and diseases of the immune system.

For people exposed to the radiation from Hanford, researchers have not yet studied the effects on the immune system. In April 1994, the Hanford Environmental Dose Reconstruction Project released draft dose estimates for representative individuals. According to these estimates, people receiving the highest exposures were still in the low-dose category for whole-body exposure (below 50 rad). Therefore, from what is known about other exposed populations, most people exposed to Hanford's releases probably did not experience a measurable decrease in lymphocytes or an increase in infections. Certain people, such as infants, young children and the elderly, tend to be at greater risk for health effects from radiation exposure.

Multiple Sclerosis

Multiple sclerosis is one disease about which some people exposed to Hanford's radioactive releases express concern. Multiple sclerosis is a disorder which damages the substance that helps to send messages along nerves. Multiple sclerosis is usually considered an autoimmune disorder.

The prevalence of multiple sclerosis is higher in some places than others. This disease occurs more often in northern latitudes and in cooler climates. Many people feel that the area downwind from Hanford has a high rate of multiple sclerosis.

There have not been any scientific studies on the number of multiple sclerosis cases in the Pacific Northwest. Such studies are very difficult and costly to do for multiple sclerosis. What information is available for this region comes from the Multiple Sclerosis Society. The Multiple Sclerosis Society keeps a count of the number of cases that individuals voluntarily report to the Society. 

Using the Society's information together with population figures for Washington state, the Multiple Sclerosis Society, Central Washington Chapter, estimated the prevalence rate of multiple sclerosis. The Society's estimated rate in Yakima, Kittitas, Benton, Franklin and Klickitat counties is 200 cases per 100,000 people. These counties are all in Eastern Washington; Benton and Franklin counties are usually considered to be in the immediate downwind area from Hanford. The Multiple Sclerosis Society puts Western Washington's rate at 65 cases per 100,000 people. Again, these rates are based on voluntary reports to the Multiple Sclerosis Society.

The highest rate of multiple sclerosis in the world that is confirmed by scientific study is 309 cases per 100,000 people in the Orkney Islands, Scotland.3 In the United States, a study of Olmsted County, Minn., found 160 cases per 100,000.4

Genetic factors, which influence inherited characteristics, may also be important in multiple sclerosis. Certain gene combinations are common in people with multiple sclerosis. One study looked at the ability of lymphocytes to repair DNA (the genetic material of the cell) and survive after exposure to radiation. It found no differences between people with multiple sclerosis and healthy people. In patients with multiple sclerosis, there may not be any increase in sensitivity to radiation.

Currently, scientists believe that there is not enough information to evaluate the relationship between Hanford radiation releases and multiple sclerosis. The high number of cases of multiple sclerosis in Central Washington may have a number of explanations. Viruses, pesticides or other environmental factors may contribute to the cause of multiple sclerosis.

downwinder perspective

 

Many callers to the Hanford Health Information Lines have reported concerns with immune system disorders and autoimmune diseases, including multiple sclerosis, lupus and rheumatoid arthritis. Scientific research has not - or at least not yet - related immune system problems to exposure to radiation released from Hanford. However, some downwinders do have these health problems and believe that they are related to Hanford. The following personal perspective is offered to help readers understand these experiences and concerns.

"Any time I become the least bit fatigued, I get sick. My lymph nodes are constantly swollen and painful. Before I was diagnosed with hypothyroidism and placed on daily thyroid medication, I had frequent urinary tract infections and cat scratch fever, which would not go away. Even now, I am sick probably 60 percent of the time with colds and congestion. I frequently require antibiotics in order to get over what would be a minor, routine illness for another person. It's really discouraging.

"It seems like my immune system is compromised and I can't help but wonder if this is related to radiation exposure from Hanford. I have done a lot of reading about the subject. As I understand it, studies available today don't tell us one way or the other whether immune system problems are related to Hanford. I've spoken with other downwinders about this. Some, like me, are ill much of the time with immune system problems. Many of the downwinders I've talked with believe these health problems are related to Hanford."

This perspective was contributed by a downwinder who was born in the Tri-Cities area and lived there until the age of 10 (during the 1950s). This downwinder recalls that, while the family lived in the Tri-Cities area, they purchased their food locally and often swam in the Columbia River. Name withheld by request.

SUMMARY

Because individuals were exposed to radioactive substances from Hanford over many years, health effects may have resulted that, at present, are not connected to radiation exposure. Current studies related to Hanford may increase our knowledge about the relationship between iodine-131 exposure and thyroid disease. Additional studies may help determine whether there is a relationship between other health problems reported by downwinders and past radioactive releases from Hanford.

High doses of radiation weaken the immune system. Even low doses can cause leukemia, a cancer of cells in the immune system. However, scientists do not have enough information now to say if there is a relationship between immune system problems experienced by downwinders and their exposure to Hanford's radioactive releases.

NOTES

1. Shigenobu Nagataki, M.D., et al. "Thyroid Diseases Among Atomic Bomb Survivors in Nagasaki." Journal of the American Medical Association, August 3, 1994; 272 (5): 364-370. Dr. Nagataki is from the Radiation Effects Research Foundation in Nagasaki. The Foundation is funded by the Japanese Ministry of Health and Welfare and the U.S. Department of Energy.

2. Michael M. Kaplan, et al. "Thyroid, Parathyroid, and Salivary Gland Evaluations in Patients Exposed to Multiple Fluoroscopic Examinations during Tuberculosis Therapy: A Pilot Study." Journal of Clinical Endocrinology and Metabolism, 1988; 66 (2): 376-382. Kaplan is an MD in the Endocrinology Division of the New England Medical Center Hospital in Boston. The research was funded by the National Cancer Institute and the National Institutes of Health.

3. A.D. Sadovnick and G.C. Ebers. "Epidemiology of Multiple Sclerosis: A Critical Overview." Le Journal Canadien des Sciences Neurologiques. 1993; 20: p. 21.

4. D.R. Wynn, M. Rodriguez, W.M. O'Fallon and L.T. Kurland. "A Reappraisal of the Epidemiology of Multiple Sclerosis in Olmsted County, Minnesota." Neurology. 1990; 10: pp. 780-786.

For Further Reading

S. Finch. "Radiation Injury." In: Wilson, J., et al. (eds.). Harrison's Principles of Internal Medicine, Twelfth Edition, Volume 2. New York: McGraw-Hill, Inc., 1991: 2204-2208.

R. Hoppe. "Effects of Irradiation on the Human Immune System." In: J.M. Vaeth and J.L. Meyer (eds.) Radiation Tolerance of Normal Tissues. Frontiers of Radiation Therapy in Oncology, Vol. 23. Basel: Karger, 1989: pp. 140-149.

Lawrence Steinman. "Autoimmune Disease." Scientific American, September 1993, pp. 107-114.

Alice Stewart and G. W. Kneale. "Non-Cancer Effects of Exposure to A-Bomb Radiation." Journal of Epidemiology and Community Health. 1984

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