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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 Information contained on the HHIN Web pages may be out-of-date.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.
Hanford is the name of a former nuclear weapons production site located in south central Washington state. Established in 1943, Hanford released radioactive materials into the air, water and soil. The releases occurred mainly as the result of routine operations but were also due to accidents and intentional releases. Many of those who lived in the areas downwind from Hanford or who used the Columbia River downstream from Hanford received doses of radiation. Those doses may have caused health problems or might cause them in the future. The basic assumption of radiation protection is that any dose of radiation poses a health risk.
This publication presents some basic information about Hanford, the radiation it released and how people were exposed to the radioactive contamination. It also provides an introduction to the possible health effects from radiation exposure. Because the largest estimated exposure from Hanford could affect the thyroid gland, this publication includes a special section on thyroid disease. Also included are descriptions of HHIN publications that offer further information.
Because of the secrecy surrounding nuclear weapons production, the public did not know much about Hanford's operational details until 1986. By February of that year, citizen pressure had forced the U.S. Department of Energy to release 19,000 pages of Hanford historical documents that had been previously unavailable to the public. These pages revealed there had been huge releases of radioactive materials into the environment that contaminated the Columbia River and more than 75,000 square miles of land. Many people were outraged at the four decades of secrecy and deception.1 They felt they had been betrayed by their own government. They demanded to know how the government could have kept such dangers secret for so long.
After the plutonium was removed from the reactors, it had to be separated and purified for use in nuclear weapons. Separating the plutonium resulted in radiation being released into the air. Winds carried Hanford's airborne radiation throughout eastern Washington, northeastern Oregon, northern Idaho and into Montana and Canada. Food grown on contaminated fields, and milk cows grazing there, transferred the radiation to people who ate the food and drank the milk. The years of highest releases to the air were 1944 through 1951, with 1945 being the largest.
HANFORD RADIATION STUDIES BEGUN
Because of public concern and anger over the once-secret information, a scientific panel, the Hanford Health Effects Review Panel, was convened in September 1986 to examine the newly released documents. The panel recommended that two studies be done to determine (1) how much radiation people had been exposed to and (2) if there was an unusually high rate of thyroid disease among those exposed. Thyroid disease was selected because the type of radiation that caused the highest exposures downwind from Hanford, iodine-131, concentrates in the thyroid gland. In previous studies of other populations, exposure to radiation has been shown to cause thyroid disease, including cancerous and non-cancerous thyroid growths.
To determine how much radiation people were exposed to, the U.S. Department of Energy began the Hanford Environmental Dose Reconstruction Project (HEDR) in 1987. Funding for HEDR was transferred to the Centers for Disease Control and Prevention (CDC) in 1992. The reason for this transfer was the Department of Energy's conflict of interest since the Department also is in charge of Hanford operations. Some people remained skeptical because CDC kept Battelle Memorial Institute as the contractor to do most of the HEDR work. Battelle has been a Hanford contractor since 1965.
In addition to the HEDR project (to determine how much radiation people were exposed to), the federal government sponsored a second study, the Hanford Thyroid Disease Study (HTDS). CDC began HTDS in 1989 and plans to complete it in late 1998. CDC has contracted with the Fred Hutchinson Cancer Research Center in Seattle to carry out the study. The HTDS is investigating whether thyroid disease, including thyroid cancer, is increased among people who were exposed as infants and children to iodine-131 from Hanford. By its completion, the study will have examined over 3,000 people for thyroid disease.
RADIATION HEALTH EFFECTS: HOW RADIATION CAUSES HARM
To understand why cancer and thyroid disease are of concern, it is useful to know how radiation can cause harm to the body. When radiation enters the body and hits a cell, one of four things can happen:
(2) it may damage the cell, but the cell may be able to repair the damage before producing new cells;
(3) it may damage the cell in such a way that the damage is passed on when new cells are formed; or
(4) it may kill the cell.
If the damage to a cell is not repaired and is passed on to new cells (number 3 above), a cancer can begin to grow. It may take years or even decades for a cancer to grow large enough to be discovered. This period between exposure to radiation and the discovery of cancer or other health effects is called the latent period. The latent period varies for different types of health effects and different types of radiation doses.
When radiation kills a cell (number 4 above), there will be acute (immediate) health effects if the dose is high and many cells die. An example of an acute effect is death within days or weeks from radiation sickness, as happened to the highly exposed people in the atomic bombings in Japan. Other acute effects include vomiting and loss of hair. From what is currently known, doses to people from Hanford's environmental releases were not enough to produce immediate or direct effects.
Radiation can cause most types of cancer. Some cells or organs - breast tissue and the thyroid, for example - are very sensitive to radiation. Others, such as bone cells, are not as sensitive.
Whether or not exposure to radiation will cause cancer depends on a variety of factors. These include: the amount and type of radiation dose; individual characteristics that make some people more susceptible to cancer than others; age; gender; whether the exposure occurred over a short or a long time; and the presence of other substances that enhance the cancer-causing power of radiation.
There has been much controversy over the extent to which low-dose radiation causes cancer. One of the more widely-known reports was published in 1990 by the Fifth Committee on the Biological Effects of Ionizing Radiations (known as BEIR V).2 BEIR V concluded that information from scientific studies about people receiving low doses was insufficient to determine cancer risk.
Overall, BEIR V concluded that cancer risk from radiation exposure is higher than regulatory and advisory groups had previously described. BEIR V estimated cancer risk but acknowledged uncertainty concerning these risk estimates. BEIR V estimated that for every 10,000 adults exposed over a short time period to 1 rem of radiation, eight would die from radiation-induced cancer.3 If the exposure took place during childhood, the risk for fatal cancer was estimated to be twice as high. BEIR V also concluded that when the dose was received over a long time, the lifetime risk of death from cancer was lower by a factor of 2 or more than if the same dose had been received over a short time. Most Hanford exposures occurred over long times (months, years or decades).
Additionally, two other scientists have been sharply critical of BEIR V. Rudi H. Nussbaum and Wolfgang Kohnlein have pointed out a number of inconsistencies within the BEIR V report. They also argue that studies published after BEIR V support the position that there is a greater risk of health effects from chronic low doses than is reflected in current radiation protection regulations.6
Why There Aren't Clear Answers
The type of radiation that caused the highest doses downwind from Hanford, iodine-131, concentrates in the thyroid gland. Exposure to some types of radiation has been shown to cause thyroid disease, including cancerous and noncancerous thyroid growths. The HTDS is gathering information on all types of thyroid disease, whether or not previous studies have suggested links between radiation exposure and thyroid disease. While the HTDS will not be completed until late 1998, thyroid disease studies from other types of radiation exposures may offer some comparisons to the Hanford situation.
Studies of Environmental Exposure to Iodine-131
People who lived downwind (downwinders) from the Nevada Test Site were exposed to nuclear fallout, including iodine-131, caused by atmospheric testing of nuclear weapons. A study of these downwinders suggests a dose-response relationship between the occurrence of thyroid growths (nodules and cancer) and iodine exposure. In this setting, a "dose-response relationship" means that the risk of having a thyroid growth (the response) increases as the dose increases. In other words, people with higher doses have greater risk than people with lower doses. The scientists who did the study concluded that the radioactive iodine exposure "probably caused" between one and 12 of the 19 cases of thyroid growths among the study population of about 2,500.7
In 1954 Marshall Islanders were exposed to radioactive fallout from a nuclear weapon test in the South Pacific. They were exposed to some iodine-131, but most of the thyroid exposure came from other radioactive forms of iodine. The Marshall Islanders suffered both acute and delayed effects from radiation. Eight years after the blast, some Marshall Islanders developed thyroid disease. After 27 years, the Marshall Islanders had an increased rate of hypothyroidism (underactive thyroid gland) and both noncancerous and cancerous thyroid growths. It is difficult to say that it was the iodine-131 or the other radioactive iodines alone that caused these thyroid problems because the Marshall Islanders also received external radiation.
Children Living Near Chernobyl
In 1995 scientists reported that the rates of thyroid cancer were significantly increased among young people who were exposed to Chernobyl's radioactive fallout.8 Before the 1986 accident, childhood thyroid cancer in the areas around Chernobyl was rare. The current rates are up to 200 times higher than normal. The rates in the table below are the number of thyroid cancers per million people. Childhood thyroid cancers are those thyroid cancers diagnosed before the children turn 15 years old.
Most (about 85 percent) of the Chernobyl thyroid dose came from iodine-131 and was received over a short time. The rest of the thyroid dose came from other radioactive isotopes of iodine. At Hanford, nearly all of the thyroid dose was from iodine-131 and was received over a number of years. HEDR estimated that children living downwind from Hanford received total thyroid doses in the range of 3 to 235 rad for the period 1944 through 1951. Because of uncertainties, the estimated dose could have been as high as 870 rad.10
Until further studies around Chernobyl are completed, it is not clear if
radioactive iodine was the only cause of the
high rates of thyroid cancer. Among other possible contributors were an iodine deficiency in the exposed
population before the accident and a higher than normal sensitivity to the harmful effects
of radiation exposure among some of those exposed.11 Another contributor could have
been the greatly increased number of thyroid examinations after the accident.12
Medical Exposures to Iodine-131
Much of what is currently known about the health effects of iodine-131
comes from studies of the medical uses of iodine-131. One group of people exposed to
iodine-131 received a one-time high dose (thousands of rad) to treat hyperthyroidism (an overactive
thyroid gland). Another group
received a one-time low dose (50-100 rad) of iodine-131 for tests to diagnose thyroid
disease. Studies of these two groups of people do not show any link between iodine-131 and thyroid cancer.
However, the length of time people were studied varied. The longest study followed people an average of 20 years. Scientists believe that the latent period for thyroid cancer can range from five to more than 40 years. They believe that the very high doses of iodine-131 used to treat people with hyperthyroidism result in killing off cells so that cancer cannot develop.
External Gamma and X-ray Radiation of the Thyroid
While there is not conclusive evidence linking iodine-131 and thyroid cancer, there is a link between thyroid cancer and exposure to X-rays and gamma radiation. Studies of people who received X-ray treatments of the head and neck show that X-rays can cause thyroid cancer. Thyroid cancer was the first solid tumor to show an increased rate in Japanese atomic bomb survivors who were exposed to gamma radiation.
Parathyroid glands help maintain the level of calcium in the body and are located around the thyroid. Studies of people receiving X-ray treatments to the head and neck have demonstrated a higher rate of hyperparathyroidism than expected. Further, those people who had hyperparathyroidism and a history of radiation treatments also had a greater frequency of thyroid disease than those who had hyperparathyroidism but did not have radiation treatments.13 Radioactive iodine in the thyroid exposes the parathyroid which may cause tumors in the parathyroid glands. The Hanford Thyroid Disease Study is investigating whether hyperparathyroidism is increased among people exposed to Hanford's radioactive releases.
OTHER RADIATION HEALTH EFFECTS
Although cancer is the most studied of all radiation health effects, exposure to radiation can harm the human body in other ways. The following are brief summaries of some other radiation health effects. Publications are available from the Network on some of these health effects.
The immune system is a complex network in the body that helps fight diseases and foreign substances. Studies have shown that radiation exposure can weaken the immune system. Autoimmune diseases are those in which a person's own immune system attacks one or more tissues or organs. These diseases include multiple sclerosis and lupus. While there have not been any studies concerning Hanford and autoimmune diseases, some Hanford-area residents are concerned that their exposure to radioactive materials has triggered such diseases. They believe that there are a higher than normal number of autoimmune disease cases among those who were exposed. For more information on the immune system and radiation's effects on it, see Immune System and Radiation.
Genetic Effects and Birth Defects
Genetic effects of radiation exposure occur when radiation damage to a parent's DNA code is transmitted to a child. (The DNA code contains information required for the development and maintenance of all organisms.) Genetic effects caused by radiation fall into two categories: (1) effects that appear in the children of an exposed parent and (2) effects that appear in later generations.
For more information about these health effects, see HHIN's Genetic Effects and Birth Defects from Radiation Exposure. This publication includes a summary of a birth defects study of children born in the Hanford area. The study found an increase in one kind of birth defects, neural tube defects. But the study's scientists did not attribute this increase to Hanford radiation exposure.
Other Effects on the Lives of Those Who Were Exposed
The secrecy surrounding the Hanford releases, the involuntary nature of the exposure and the lack of information about radiation health effects have left some people understandably frustrated, mistrustful and angry. Many people report feeling that the emotional and economic toll has been great. This is especially true for those who have thyroid diseases and other illnesses and whose family members, friends and neighbors are ill or have died. For additional reading on these aspects, see HHIN's Coping with Uncertainty and Illness: Concerns of Hanford Downwinders.
1 - For further reading about Hanford, secrecy and deception, see Atomic Harvest: Hanford and the Lethal Toll of America's Nuclear Arsenal by Michael D'Antonio (Crown Pub. 1993); The Dragon's Tail: Radiation Safety in the Manhattan Project, 1942-1946 by Barton C. Hacker (University of California 1987); On the Home Front: The Cold War Legacy of the Hanford Nuclear Site by Michele Stenehjem Gerber (University of Nebraska 1992); and Sordid Sorcery: The History of Hanford's Deception by the Hanford Education Action League (HEAL 1992).
2 - National Research Council (BEIR V). Health Effects of Exposure to Low Levels of Ionizing Radiation. National Academy Press, 1990. BEIR V was a committee of 17 scientists from the National Academy of Sciences. The chair of BEIR V was Arthur C. Upton.
3 - BEIR V, p. 162.
4 - T. Straume, et al. "Neutron Discrepancies in the DS86 Hiroshima Dosimetry System." Health Physics, October 1992, Vol. 63, No. 4, pp. 421-426. In 1992, Straume was with Lawrence Livermore National Laboratory. His colleagues were from SAIC in San Diego, the University of Rochester (N.Y.) and Hiroshima University.
5 - J.W. Gofman. Radiation-Induced Cancer from Low-Dose Exposure: An Independent Analysis. Committee for Nuclear Responsibility, 1990, chapter 25, p. 15. Gofman is Professor Emeritus of Molecular and Cellular Biology at the University of California, Berkeley.
6 - R.H. Nussbaum and Wolfgang Kohnlein. "Inconsistencies and Open Questions Regarding Low-Dose Health Effects of Ionizing Radiation." Environmental Health Perspectives, Vol. 102, No. 8, August 1994, pp. 656-667. Nussbaum is Professor Emeritus of Physics and Environmental Sciences at Portland (OR) State University. Kohnlein is professor and director of the Institute for Radiation Biology at the University of Munster in Germany. See also "Health Consequences of Exposures to Ionizing Radiation from External and Internal Sources: Challenges to Radiation Protection Standards and Biomedical Research," Medicine and Global Survival, Vol. 2, No. 4, December 1995, pp. 198-213.
7 - R.A. Kerber, et al. "A Cohort Study of Thyroid Disease in Relation to Fallout From Nuclear Weapons Testing." Journal of the American Medical Association, Vol. 270, No. 17, November 3, 1993, p. 2082.
8 - V.A. Stsjazhko, et al. "Childhood Thyroid Cancer Since Accident at Chernobyl" (letter). British Medical Journal, Vol. 310, March 25, 1995, p. 801.
9 - Table is adapted from V.A. Stsjazhko, et al. "Childhood Thyroid Cancer Since Accident at Chernobyl" (letter). British Medical Journal, Vol. 310, March 25, 1995, p. 801.
10 - Technical Steering Panel of the Hanford Environmental Dose Reconstruction Project. Representative Hanford Radiation Dose Estimates, Revision 1. April 21, 1994, p. 2.
11 - M. Balter. "Children Become the First Victims of Fallout." Science, Vol. 272, April 19, 1996, p. 359.
12 - E. Ron, J. Lubin, and A.B. Schneider. "Thyroid Cancer Incidence." Nature, Vol. 360, November 12, 1992, p. 113. Ron and Lubin are with the Epidemiology and Biostatistics Program at the National Cancer Institute. Schneider is with Humana and Michael Reese hospitals at the University of Illinois.
13 - A. Katz and G.D. Braunstein. "Clinical, Biochemical, and Pathologic Features of Radiation-Associated Hyperpara-thyroidism." Archives of Internal Medicine, Vol. 143, January 1983, pp. 79-82.
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