Radiation injuries

Definition

Radiation injuries are caused by ionizing radiation emitted by such sources as the sun, x-ray and other diagnostic machines, tanning beds, and radioactive elements

released in nuclear power plant accidents and detonation of nuclear weapons during war and as terrorist acts.

Description

Ionizing radiation is made up of unstable atoms that contain an excess amount of energy. In an attempt to stabilize, the atoms emit the excess energy into the atmosphere, creating radiation. Radiation can either be electromagnetic or particulate.

The energy of electromagnetic radiation is a direct function of its frequency. The high energy, high frequency waves that can penetrate solids to various depths cause damage by separating molecules into electrically charged pieces, a process known as ionization. X rays are a type of electromagnetic radiation. Atomic particles come from radioactive isotopes as they decay to stable elements. Electrons are called beta particles when they radiate. Alpha particles are the nuclei of helium atoms—two protons and two neutrons—without the surrounding electrons. Alpha particles are too large to penetrate a piece of paper unless they are greatly accelerated in electric and magnetic fields. Both beta and alpha particles are types of particulate radiation. When over-exposure to ionizing radiation occurs, there is chromosomal damage in deoxyribonucleic acid (DNA). DNA is very good at repairing itself; both strands of the double helix must be broken to produce genetic damage.

Because radiation is energy, it can be measured. There are a number of units used to quantify radiation energy. Some refer to effects on air, others to effects on living tissue. The roentgen, named after Wilhelm Conrad Roentgen, who discovered x rays in 1895, measures ionizing energy in air. A rad expresses the energy transferred to tissue. The rem measures tissue response. A roentgen generates about a rad of effect and produces about a rem of response. The gray and the sievert are international units equivalent to 100 rads and rems, respectively. A curie, named after French physicists who experimented with radiation, is a measure of actual radioactivity given off by a radioactive element, not a measure of its effect. The average annual human exposure to natural background radiation is roughly 3 milliSieverts (mSv).

Any amount of ionizing radiation will produce some damage; however, there is radiation everywhere, from the sun (cosmic rays) and from traces of radioactive elements in the air (radon) and the ground (uranium, radium, carbon-14, potassium-40 and many others). Earth's atmosphere protects us from most of the sun's radiation. Living at 5,000 feet altitude in Denver, Colorado, doubles exposure to radiation, and flight in a commercial airliner increases it 150-fold by lifting us above 80% of that atmosphere. Because no amount of radiation is perfectly safe and because radiation is ever present, arbitrary limits have been established to provide some measure of safety for those exposed to unusual amounts. Less than 1% of them reach the current annual permissible maximum of 20 mSv.

A 2001 ruling by the Federal Court of Australia indicated that two soldiers died from cancer caused by minimal exposure to radiation while occupying Hiroshima in 1945. The soldiers were exposed to less than 5 mSv of radiation. The international recommendation for workers is safety level of up to 20 mSv. The ruling and its support by many international agencies suggests that even extremely low doses of radiation can be potentially harmful.

Ultraviolet (UV) radiation exposure from the sun and tanning beds

UV radiation from the sun and tanning beds and lamps can cause skin damage, premature aging , and skin cancers. Malignant melanoma is the most dangerous of skin cancers and there is a definite link between type UVA exposure used in tanning beds and its occurrence. UVB type UV radiation is associated with sunburn , and while not as penetrating as UVA, it still damages the skin with over exposure. Skin damage accumulates over time, and effects do not often manifest until individuals reach middle age. Light-skinned people who most often burn rather than tan are at a greater risk of skin damage than darkerskinned individuals that almost never burn. The U.S. Food and Drug Administration (FDA) and the Centers for Disease Control (CDC) discourage the use of tanning beds and sun lamps and encourage the use of sunscreen with at least an SPF of 15 or greater. In addition, the rising incidence of melanoma in the United States has led the Environmental Protection Agency (EPA) to develop a sun safety education program for school-age children in order to begin changing public attitudes toward tanning.

Overexposure during medical procedures

Ionizing radiation has many uses in medicine, both in diagnosis and in treatment. X rays, CT scanners, and fluoroscopes use it to form images of the body's insides. Nuclear medicine uses radioactive isotopes to diagnose and to treat medical conditions. In the body, radioactive elements localize to specific tissues and give off tiny amounts of radiation. Detecting that radiation provides information on both anatomy and function. During the past 10 years, skin injuries caused by too much exposure during a medical procedure have been documented. In 1995, the FDA issued a recommendation to physicians and medical institutions to record and monitor the dosage of radiation used during medical procedures on patients in order to minimize the amount of skin injuries. The FDA suggested doses of radiation not exceed 1 Grey (Gy). (A Grey is roughly equivalent to a sievert.) As of 2001, the FDA was preparing further guidelines for fluoroscopy, the procedure most often associated with medical-related radiation skin injuries such as rashes and more serious burns and tissue death. Injuries occurred most often during angioplasty procedures using fluoroscopy.

CT scans of children have also been problematic. Oftentimes the dosage of radiation used for an adult isn't decreased for a child, leading to radiation overexposure. Children are more sensitive to radiation; a February 2001 study indicates 1,500 out of 1.6 million children under 15 years of age receiving CT scans annually will develop cancer. Studies show that decreasing the radiation by half for CT scans of children will effectively decrease the possibility of overexposure while still providing an effective diagnostic image. The benefits to receiving the medical treatment utilizing radiation is still greater than the risks involved; however, more stringent control over the amount of radiation used during the procedures will go far to minimize the risk of radiation injury to the patient.

Recent evidence suggests that some ethnic groups may be more vulnerable than others to radiation damage. A study done at New York University found that Jews are more likely to develop ovarian cancer as a delayed side effect of diagnostic x-rays of the abdomen than non-Jews. These findings require confirmation by further research, but they do indicate that ethnicity and other genetic factors are involved in susceptibility to radiation damage.

Side effects from radiation therapy to treat cancer

As many as half of all cancer patients receive some form of radiation therapy as a component of treatment.

The therapy can be delivered from either an external or an internal source, although the former is more common. The machines used for external radiation have become more specialized to deliver the appropriate dose to either a superficial or a deep location on the body. Depending on the type and site of cancer being treated, internal sources of radiation can be injected, swallowed, or placed within the body in sealed containers. These are implanted into or near the tumor, either temporarily or permanently.

Some types of tumors may be eliminated by radiation therapy, if the patient is able to withstand the necessary dose. In other cases, radiation is used in conjunction with other methods of treatment. It may be given before surgery, to shrink a tumor to an operable size, or after surgery, to try to destroy any cancerous cells that may remain. Radiation can be used to make patients with incurable disease more comfortable by decreasing the bulk of tumors to reduce pain or pressure. Treatment that is given as a comfort measure only is known as palliation, or palliative therapy.

Occupational radiation exposure

Specialists in industrial and occupational health are increasingly aware of the rising number of injuries related to on-the-job radiation exposure. One study of Swedish workers exposed to high levels of low-frequency magnetic fields found an increased incidence of kidney, liver, and pituitary gland tumors among the men, and a higher rate of leukemia and brain tumors among the women.

Sadly, the delayed effects of occupational radiation exposure have also delayed the adoption of necessary protection for workers at risk. A study of the high rate of lung cancer among Navajo Indians who worked in uranium mines during World War II did not bring about even partial protection for the miners until 1962. It was not until 1990 that Congress passed the Radiation Exposure Compensation Act to provide care for the injured miners. he effects of cosmic radiation on human beings are also being investigated because of concern for the safety of air crew. Although findings are still inconclusive as of 2002, recent reports of an increased incidence of cancer among airline pilots and cabin crew members have led epidemiologists to study the long-term effects of cosmic radiation at the altitudes of modern aircraft flight.

Radiation exposure from nuclear accidents, weaponry, and terrorist acts

Between 1945 and 1987, there were 285 nuclear reactor accidents, injuring over 1,550 people and killing 64. The most striking example was the meltdown of the graphite core nuclear reactor at Chernobyl in 1986, which spread a cloud of radioactive particles across the entire continent of Europe. Information about radiation effects is still being gathered from that disaster, however 31 people were killed in the immediate accident and 1,800 children have thus far been diagnosed with thyroid cancer. In a study published in May 2001 by the British Royal Society, children born to individuals involved in the cleanup of Chernobyl and born after the accident are 600% more likely to have genetic mutations than children born before the accident. These findings indicate that exposure to low doses of radiation can cause inheritable effects.

Since the terrorist attack on the World Trade Center and the Pentagon on September 11, 2001, the possibility of terrorist-caused nuclear accidents has been a growing concern. All 103 active nuclear power plants in the United States are on full alert, but they are still vulnerable to sabotage such as bombing or attack from the air. A nofly zone of 12 miles below 18,000 feet has been established around nuclear power plants by the Federal Aviation Administration (FAA). There is also growing concern over the security of spent nuclear fuel—more than 40,000 tons of spent fuel is housed in buildings at closed plants around the country. Unlike the active nuclear reactors that are enclosed in concrete-reinforced buildings, the spent fuel is stored in non-reinforced buildings. Housed in cooling pools, the spent fuel could emit dangerous levels of radioactive material if exploded or used in makeshift weaponry. Radioactive medical and industrial waste could also be used to make "dirty bombs." Since 1993, the Nuclear Regulatory Commission (NRC) has reported 376 cases of stolen radioactive materials.

One response on the part of health care workers has been stepped-up training in radiation disaster management. Emergency department personnel are being trained as of 2002 to use radiologic monitoring and other specialized equipment for treating victims of a terrorist attack involving radiation.

Causes & symptoms

Radiation can damage every tissue in the body. The particular manifestation will depend upon the amount of radiation, the time over which it is absorbed, and the susceptibility of the tissue. The fastest growing tissues are the most vulnerable, because radiation as much as triples its effects during the growth phase. Bone marrow cells that make blood are the fastest growing cells in the body. A fetus in the womb is equally sensitive. The germinal cells in the testes and ovaries are only slightly less sensitive. Both can be rendered useless with very small doses of radiation. More resistant are the lining cells of the body—skin and intestines. Most resistant are the brain cells, because they grow the slowest.

The length of exposure makes a big difference in what happens. Over time the accumulating damage, if not enough to kill cells outright, distorts their growth and causes scarring and/or cancers. In addition to leukemias, cancers of the thyroid, brain, bone, breast, skin, stomach, and lung all arise after radiation. Damage depends, too, on the ability of the tissue to repair itself. Some tissues and some types of damage produce much greater consequences than others.

There are three types of radiation injuries.

• External irradiation: as with x-ray exposure, all or part of the body is exposed to radiation that either is absorbed or passes through the body.
• Contamination: as with a nuclear accident, the environment and its inhabitants are exposed to radiation. People are affected internally, externally, or with both internal and external exposure.
• Incorporation: dependent on contamination, the bodies of individuals affected incorporate the radiation chemicals within cells, organs, and tissues and the radiation is dispersed throughout the body.

Immediately after sudden irradiation, the fate of those affected depends mostly on the total dose absorbed. This information comes mostly from survivors of the atomic bomb blasts over Japan in 1945.

• Massive doses incinerate immediately and are not distinguishable from the heat of the source.
• A sudden whole-body dose over 50 Sv produces such profound neurological, heart, and circulatory damage that patients die within the first two days.
• Doses in the 10–20 Sv range affect the intestines, stripping their lining and leading to death within three months from vomiting, diarrhea, starvation , and infection.
• Victims receiving 6–10 Sv all at once usually escape an intestinal death, facing instead bone marrow failure and death within two months from loss of blood coagulation factors and the protection against infection provided by white blood cells.
• Between 2–6 Sv gives the person a fighting chance for survival if he or she is supported with blood transfusions and antibiotics .
• One or two Sv produces a brief nonlethal sickness with vomiting, loss of appetite, and generalized discomfort.

Side effects of radiation therapy

Damage caused to normal cells can show up either in the time frame shortly following radiation treatment, or as long as years after radiation has been completed. Symptoms that frequently occur soon after treatment include loss of appetite, fatigue , and skin changes. Less commonly, patients have headache, nausea , vomiting, hair loss , and weakness. In more severe cases, dehydration, seizures, and shock-type reactions can occur. The severity and type of effects will depend on the region of the body receiving treatment, the type of radiation used during the course of treatment, and the dose. There is also individual variation in the response. Skin rashes are common. They may take the form of redness, burn, dryness, itching , or soreness. Organs that were in the path of the beam may show changes, including scarring, functional changes (such as decrease in elasticity), and loss of cells. Tissues that have a rapid turnover of cells may be most severely affected, including the skin and lining of the gastrointestinal tract. More severe injuries may include long-term bone marrow suppression, and occasionally even other cancers, particularly sarcomas.

People who receive radiation in the region of the head and neck are likely to experience a dry and sore mouth to some degree. The skin may become dry, and the area under the chin may droop. Sense of taste can be altered or lost. Some may experience hair loss, earaches, or difficulty swallowing due to inflammation of the esophagus.

Radiation treatments given for or around the breast, chest, or lung can also cause esophagitis and accompanying trouble swallowing. Changes in the lung tissue may lead to pneumonitis or pulmonary fibrosis. The patient may develop a cough . Breast treatments may cause pain and swelling. Blood counts can decrease.

Side effects from treatment of the stomach and abdominal area can induce nausea and diarrhea. In the pelvic region, radiation may result in difficulties with urination, and infertility in both males and females. Women may also have symptoms of dryness, itching, or burning of the vagina.

Diagnosis

The various effects of radiation on the body are well recognized. Patients who are scheduled to undergo radioactive treatments should be informed of the potential side effects they will encounter based on the area being treated and the dose of radiation being used. Advice for coping with minor injuries should be given, as well as descriptions of what symptoms should prompt a call or a visit to the treating physician.

Treatment

It is clearly important to have some idea of the dose received as early as possible, so that attention can be directed to those victims in the 2-10 Sv range that might survive with treatment. Blood transfusions, protection from infection in damaged organs, and possibly the use of newer stimulants to blood formation can save many victims in this category.

Local radiation exposures usually damage the skin and require careful wound care, removal of dead tissue, and skin grafting if the area is large. Again infection control is imperative.

One of the best-known, and perhaps even mainstream, treatments of radiation injury is the use of Aloe vera preparations on damaged areas of skin. It has demonstrated remarkable healing properties even for chronic ulcerations resulting from radiation treatment. Another topical herb that may be effective against skin inflammation following radiation therapy is chamomile cream. Studies support the benefits of chamomile for skin inflammation and wound healing. Additional topical herbs that may be helpful are calendula and St. John's wort . These therapies can prove very helpful since skin reaction is one of the most common side effects of radiation therapy.

Guided imagery is a method that may be used following radiation treatment, especially to help ease pain. Several nutritional supplements help with healing wounds . These include essential fatty acids (Omega 3 and 6), vitamin A , vitamin B, and magnesium/zinc.

If the tumor being treated is determined to be sensitive to radiation, there are a few herbs that are said to reduce the adverse effects of radiation exposure. Ginseng is one that research suggests may have this benefit. Other nutrients thought to have some protective effects are coenzyme Q10, kelp, pantothenic acid , and glutathione with L-cysteine and L-methionine. Garlic and vitamin C support immune function. Grape seed extract is a powerful antioxidant that protects against cell damage by free radicals. Any nutritional measures to support optimum health before treatment are beneficial.

Allopathic treatment

The type of treatment used depends on the area and severity of the injury. Something as serious as bone marrow suppression would require more intensive therapy, whereas more minor conditions are treated symptomatically. Radiation-induced esophagitis may necessitate intravenous or gastrostomy feeding for a time until the injury is healed. If a perforation or a stricture develops, surgery may be necessary. Products are available to keep the eyes (drops with vitamin A) and oral mucosa moist, as the cells producing mucus and tears are often damaged.

Expected results

Tissue damage resulting from radiation exposure tends to be chronic in nature, and may even be progressive. For the lesser and more common types of problems, long-term treatment of symptoms should be anticipated.

Prevention

Part of preventing radiation injury involves doing research on the condition being treated. It is a good idea to be certain that radiation is the best available treatment for a particular cancer type before embarking on a course of therapy.

Information on preventing or minimizing damage from radiation produced by terrorist devices or other nuclear emergencies is available in a series of fact sheets that can be downloaded from the Centers for Disease Control (CDC) web site. The fact sheets cover such topics as basic radiation facts, acute radiation sickness (ARS), dirty bombs, effects of radiation on health, possible effects of radiation on unborn children, and protective measures in the case of a nuclear event.

Resources

BOOKS

Altman, Robert, and Michael Sarg. The Cancer Dictionary, revised edition. New York: Checkmark Books, 2000.

Balch, James, and Phyllis Balch. Prescription for Nutritional Healing. New York: Avery Publishing Group, 1997.

Johns Hopkins University. Johns Hopkins Family Health Book. New York: HarperCollins Publishers, 1999.

PERIODICALS

Brugge, D., and R. Goble. "The History of Uranium Mining and the Navajo People." American Journal of Public Health 92 (September 2002): 1410-1419.

"'Dirty Bomb' Threat Puts Spotlight on Unprepared EDs: Do You Have a Plan?" ED Management 14 (September 2002): 97-100.

Fears, T. R., C. C. Bird, D. Guerry 4th, et al. "Average Midrange Ultraviolet Radiation Flux and Time Outdoors Predict Melanoma Risk." Cancer Research 62 (July 15, 2002): 3992-3996.

Grunwald, Michael and Peter Behr. "Are Nuclear Plants Secure? Industry Called Unprepared for Sept. 11-Style Attack." Washington Post, November 3, 2001, p. A01.

Hakansson, N., B. Floderus, P. Gustavsson, et al. "Cancer Incidence and Magnetic Field Exposure in Industries Using Resistance Welding in Sweden." Occupational and Environmental Medicine 59 (July 2002): 481-486.

Harlap, S., S. H. Olson, R. R. Barakat, et al. "Diagnostic X Rays and Risk of Epithelial Ovarian Carcinoma in Jews." Annals of Epidemiology 12 (August 2002): 426-434.

Lim, M. K. "Cosmic Rays: Are Air Crew at Risk?" Occupational and Environmental Medicine 59 (July 2002): 428-432.

Vergano, Dan. "'Dirty' Bombs Latest Fear." USA Today, November 3, 2001.

ORGANIZATIONS

American College of Occupational and Environmental Medicine (ACOEM). 1114 North Arlington Heights Road, Arlington Heights, IL 60004. (847) 818-1800. <www.acoem.org>.

Centers for Disease Control and Prevention (CDC). 1600 Clifton Road, Atlanta, GA 30333. (404) 639-3311. <www.cdc.gov>.

Judith Turner

Rebecca J. Frey, PhD

Radiation Injuries

Definition

Radiation injuries are caused by ionizing radiation emitted by sources such as the sun, x-ray and other diagnostic machines, tanning beds, and radioactive elements released in nuclear power plant accidents and detonation of nuclear weapons during war and as terrorist acts.

Description

Ionizing radiation is made up of unstable atoms that contain an excess amount of energy. In an attempt to stabilize, the atoms emit the excess energy into the atmosphere, creating radiation. Radiation can either be electromagnetic or particulate.

The energy of electromagnetic radiation is a direct function of its frequency. The high-energy, high-frequency waves that can penetrate solids to various depths cause damage by separating molecules into electrically charged pieces, a process known as ionization. X rays are a type of electromagnetic radiation. Atomic particles come from radioactive isotopes as they decay to stable elements. Electrons are called beta particles when they radiate. Alpha particles are the nuclei of helium atoms—two protons and two neutrons—without the surrounding electrons. Alpha particles are too large to penetrate a piece of paper unless they are greatly accelerated in electric and magnetic fields. Both beta and alpha particles are types of particulate radiation. When over-exposure to ionizing radiation occurs, there is chromosomal damage in deoxyribonucleic acid (DNA). DNA is very good at repairing itself; both strands of the double helix must be broken to produce genetic damage.

Because radiation is energy, it can be measured. There are a number of units used to quantify radiation energy. Some refer to effects on air, others to effects on living tissue. The roentgen, named after Wilhelm Conrad Roentgen, who discovered x rays in 1895, measures ionizing energy in air. A rad expresses the energy transferred to tissue. The rem measures tissue response. A roentgen generates about a rad of effect and produces about a rem of response. The gray and the sievert are international units equivalent to 100 rads and rems, respectively. A curie, named after French physicists who experimented with radiation, is a measure of actual radioactivity given off by a radioactive element, not a measure of its effect. The average annual human exposure to natural background radiation is roughly 3 milliSieverts (mSv).

Any amount of ionizing radiation will produce some damage, however, there is radiation everywhere, from the sun (cosmic rays) and from traces of radioactive elements in the air (radon) and the ground (uranium, radium, carbon-14, potassium-40 and many others). Earth's atmosphere protects us from most of the sun's radiation. Living at 5,000 feet altitude in Denver, Colorado, doubles exposure to radiation, and flight in a commercial airliner increases it 150-fold by lifting us above 80% of that atmosphere. Because no amount of radiation is perfectly safe and because radiation is ever present, arbitrary limits have been established to provide some measure of safety for those exposed to unusual amounts. Less than 1% of them reach the current annual permissible maximum of 20 mSv.

A 2001 ruling by the Federal Court of Australia indicated that two soldiers died from cancer caused by minimal exposure to radiation while occupying Hiroshima in 1945. The soldiers were exposed to less than 5 mSv of radiation. The international recommendation for workers is safety level of up to 20 mSv. The ruling and its support by many international agencies suggests that even extremely low doses of radiation can be potentially harmful.

Ultraviolet (UV) radiation exposure from the sun and tanning beds

UV radiation from the sun and tanning beds and lamps can cause skin damage, premature aging, and skin cancers. Malignant melanoma is the most dangerous of skin cancers and there is a definite link between type UVA exposure used in tanning beds and its occurrence. UVB type UV radiation is associated with sunburn, and while not as penetrating as UVA, it still damages the skin with over exposure. Skin damage accumulates over time, and effects do not often manifest until individuals reach middle age. Light-skinned people who most often burn rather than tan are at a greater risk of skin damage than darker-skinned individuals that almost never burn. The U.S. Food and Drug Administration (FDA) and the Centers for Disease Control (CDC) discourage the use of tanning beds and sun lamps and encourage the use of sunscreen with at least an SPF of 15 or greater.

Over exposure during medical procedures

Ionizing radiation has many uses in medicine, both in diagnosis and in treatment. X rays, CT scanners, and fluoroscopes use it to form images of the body's insides. Nuclear medicine uses radioactive isotopes to diagnose and to treat medical conditions. In the body, radioactive elements localize to specific tissues and give off tiny amounts of radiation. Detecting that radiation provides information on both anatomy and function. During the past 10 years, skin injuries caused by too much exposure during a medical procedure have been documented. In 1995, the FDA issued a recommendation to physicians and medical institutions to record and monitor the dosage of radiation used during medical procedures on patients in order to minimize the amount of skin injuries. The FDA suggested doses of radiation not exceed 1 Grey (Gy). (A Grey is roughly equivalent to a sievert.) As of 2001, the FDA was preparing further guidelines for fluoroscopy, the procedure most often associated with medical-related radiation skin injuries such as rashes and more serious burns and tissue death. Injuries occurred most often during angioplasty procedures using fluoroscopy.

CT scans of children have also been problematic. Oftentimes the dosage of radiation used for an adult isn't decreased for a child, leading to radiation over exposure. Children are more sensitive to radiation and a February 2001 study indicates 1,500 out of 1.6 million children under 15 years of age receiving CT scans annually will develop cancer. Studies show that decreasing the radiation by half for CT scans of children will effectively decrease the possibility of over exposure while still providing an effective diagnostic image. The benefits to receiving the medical treatment utilizing radiation is still greater than the risks involved, however, more stringent control over the amount of radiation used during the procedures will go far to minimize the risk of radiation injury to the patient.

Radiation exposure from nuclear accidents, weaponry, and terrorist acts

Between 1945 and 1987, there were 285 nuclear reactor accidents, injuring over 1,550 people and killing 64. The most striking example was the meltdown of the graphite core nuclear reactor at Chernobyl in 1986, which spread a cloud of radioactive particles across the entire continent of Europe. Information about radiation effects is still being gathered from that disaster, however 31 people were killed in the immediate accident and 1,800 children have thus far been diagnosed with thyroid cancer. In a study published in May 2001 by the British Royal Society, children born to individuals involved in the cleanup of Chernobyl and born after the accident are 600% more likely to have genetic mutations than children born before the accident. These findings indicate that exposure to low doses of radiation can cause inheritable effects.

Since the terrorist attack on the World Trade Center and the Pentagon on September 11, 2001, the possibility of terrorist-caused nuclear accidents has been a growing concern. All 103 active nuclear power plants in the United States are on full alert, but they are still vulnerable to sabotage such as bombing or attack from the air. A no-fly zone of 12 miles below 18,000 feet has been established around nuclear power plants by the Federal Aviation Administration (FAA). There is also growing concern over the security of spent nuclear fuel—more than 40,000 tons of spent fuel is housed in buildings at closed plants around the country. Unlike the active nuclear reactors that are enclosed in concrete-reinforced buildings, the spent fuel is stored in non-reinforced buildings. Housed in cooling pools, the spent fuel could emit dangerous levels of radioactive material if exploded or used in makeshift weaponry. Radioactive medical and industrial waste could also be used to make "dirty bombs." Since 1993, the Nuclear Regulatory Commission (NRC) has reported 376 cases of stolen radioactive materials.

Causes and symptoms

Radiation can damage every tissue in the body. The particular manifestation will depend upon the amount of radiation, the time over which it is absorbed, and the susceptibility of the tissue. The fastest growing tissues are the most vulnerable, because radiation as much as triples its effects during the growth phase. Bone marrow cells that make blood are the fastest growing cells in the body. A fetus in the womb is equally sensitive. The germinal cells in the testes and ovaries are only slightly less sensitive. Both can be rendered useless with very small doses of radiation. More resistant are the lining cells of the body—skin and intestines. Most resistant are the brain cells, because they grow the slowest.

The length of exposure makes a big difference in what happens. Over time the accumulating damage, if not enough to kill cells outright, distorts their growth and causes scarring and/or cancers. In addition to leukemias, cancers of the thyroid, brain, bone, breast, skin, stomach, and lung all arise after radiation. Damage depends, too, on the ability of the tissue to repair itself. Some tissues and some types of damage produce much greater consequences than others.

There are three types of radiation injuries.

• External irradiation: as with x-ray exposure, all or part of the body is exposed to radiation that either is absorbed or passes through the body.
• Contamination: as with a nuclear accident, the environment and its inhabitants are exposed to radiation. People are affected internally, externally, or with both internal and external exposure.
• Incorporation: dependent on contamination, the bodies of individuals affected incorporate the radiation chemicals within cells, organs, and tissues and the radiation is dispersed throughout the body.

Immediately after sudden irradiation, the fate of those affected depends mostly on the total dose absorbed. This information comes mostly from survivors of the atomic bomb blasts over Japan in 1945.

• Massive doses incinerate immediately and are not distinguishable from the heat of the source.
• A sudden whole body dose over 50 Sv produces such profound neurological, heart, and circulatory damage that patients die within the first two days.
• Doses in the 10-20 Sv range affect the intestines, stripping their lining and leading to death within three months from vomiting, diarrhea, starvation, and infection.
• Victims receiving 6-10 Sv all at once usually escape an intestinal death, facing instead bone marrow failure and death within two months from loss of blood coagulation factors and the protection against infection provided by white blood cells.
• Between 2-6 Sv gives a fighting chance for survival if victims are supported with blood transfusions and antibiotics.
• One or two Sv produces a brief, non-lethal sickness with vomiting, loss of appetite, and generalized discomfort.

Treatment

It is clearly important to have some idea of the dose received as early as possible, so that attention can be directed to those victims in the 2-10 Sv range that might survive with treatment. Blood transfusions, protection from infection in damaged organs, and possibly the use of newer stimulants to blood formation can save many victims in this category.

Local radiation exposures usually damage the skin and require careful wound care, removal of dead tissue, and skin grafting if the area is large. Again infection control is imperative.

One of the best known, and perhaps even mainstream, treatments of radiation injury is the use of Aloe vera preparations on damaged areas of skin. It has demonstrated remarkable healing properties even for chronic ulcerations resulting from radiation exposure.

Alternative treatment

There is considerable interest these days in benevolent chemicals called "free radical scavengers." How well they work is yet to be determined, but population studies strongly suggest that certain diets are better than others, and that those diets are full of free radical scavengers, otherwise known as antioxidants. The recommended ingredients are beta-carotene, vitamins E and C, and selenium, all available as commercial preparations. Beta-carotene is yellow-orange and is present in yellow and orange fruits and vegetables. Vitamin C can be found naturally in citrus fruits. Traditional Chinese medicine (TCM) and acupuncture, botanical medicine, and homeopathy all have contributions to make to recovery from the damage of radiation injuries. The level of recovery will depend on the exposure. Consulting practitioners trained in these modalities will result in the greatest benefit.

Resources

PERIODICALS

Grunwald, Michael, and Peter Behr. "Are Nuclear Plants Secure? Industry Called Unprepared for Sept. 11-Style Attack." The Washington Post November 3, 2001, p. A01.

Vergano, Dan. "'Dirty' Bombs Latest Fear." USA Today November 3, 2001.

KEY TERMS

DNA— Deoxyribonucleic acid. The chemical of chromosomes and hence the vehicle of heredity.

Isotope— An unstable form of an element that gives off radiation to become stable. Elements are characterized by the number of electrons around each atom. One electron's negative charge balances the positive charge of each proton in the nucleus. To keep all those positive charges in the nucleus from repelling each other (like the same poles of magnets), neutrons are added. Only certain numbers of neutrons work. Other numbers cannot hold the nucleus together, so it splits apart, giving off ionizing radiation. Sometimes one of the split products is not stable either, so another split takes place. The process is called radioactivity.

RADIATION INJURIES

DEFINITION

Radiation injuries are damage to the body caused by ionizing radiation. Ionizing radiation (IR) is given off by the sun, X-ray machines, and radioactive elements.

DESCRIPTION

The word radiation comes from a Latin term that means "ray of light." It is used in a general sense to cover all forms of energy that travel through space from one place to another as "rays." Some forms of radiation are relatively harmless, like radio waves. Some forms of radiation carry a tremendous amount of energy and cause damage when they come into contact with other materials.

These high energy forms of radiation cause damage to substances by tearing apart the atoms and molecules that make up the substances. This may cause materials to undergo harmful changes. For example, an X ray that passes through water can tear the molecules of water apart. An X ray that passes through a living cell can also damage the cell by tearing apart the chemicals that make up the cell. The cell may be badly injured or killed.

Any form of radiation that can tear atoms and molecules apart is called ionizing radiation (IR). Damage to the body caused by IR is known as radiation injury. Ionizing radiation can come in the form electromagnetic waves or subatomic particles.

Electromagnetic Waves

Radio and television signals, radar, heat, infrared and ultraviolet radiation, sunlight, starlight, gamma rays, cosmic rays, and X rays are all forms of electromagnetic radiation (ER). All forms of electromagnetic radiation travel in the form of waves at the speed of light (182,282 miles per second, 299,727 kilometers per second). Because ER travels in waves, its energy can be expressed in terms of wavelengths. Types of ER differ with regard to wavelength. The higher the energy wave, the shorter its wavelength. Types of ER also differ from one another with regard to their frequency. The frequency of a wave is the rate at which it vibrates in space.

X rays, gamma rays, and cosmic rays all have very high frequencies and short wavelengths. They vibrate very rapidly—many billions of times per second—in space. Radio and television signals and radar all have very low frequencies and long wavelengths. They vibrate quite slowly in space.

Waves that vibrate rapidly (have high frequencies) are carry more energy and can cause damage to substances by tearing apart the atoms and molecules that make up the substances.

Radiation Injuries: Words to Know

Bone marrow:

Tissue found in the center of bones from which all types of blood cells are formed.

Electromagnetic radiation (ER):

Radiation that travels as waves at the speed of light.

Frequency:

The rate at which a wave vibrates in space.

Gray (Gy):

A unit used to measure the amount of damage done to tissue by ionizing radiation.

Ionizing radiation (IR):

Any form of radiation that can break apart atoms and molecules and cause damage to materials.

Rad:

An older unit used to measure the amount of damage done to tissue by ionizing radiation, now replaced by the gray.

Radiation:

Energy transmitted in the form of electromagnetic waves or subatomic particles.

Radioactive element:

An element that gives off some form of radiation and breaks down into a different element or a different form of the same element.

Rem:

An older unit used to measure the amount of damage done to tissue by ionizing radiation, now replaced by the sievert.

Sievert (Sv):

A unit used to measure the amount of damage done to tissue by ionizing radiation.

Particulate Radiation

Radioactive elements also give off forms of radiation similar to electro-magnetic radiation, but it is given off in sprays of subatomic particles. These particles may be produced intentionally in machines know as particle accelerators (atom-smashers) or they may be given off spontaneously by naturally occurring radioactive materials such as uranium 235 and radium 226. These forms of radiation can also cause damage to atoms and molecules.

Measuring Damage

There are two units used to measure the damage done to tissue by ionizing radiation. Those units were once called the rad and the rem. They have now been given new names, the gray (Gy) and the sievert (Sv). These units are very similar to, but not exactly the same as, each other.

The damage IR causes to a body can range from very mild to very severe. The damage depends on a number of factors, including the kind of radiation, how close the person is to the source of radiation, and how long the person was exposed to the radiation. In mild cases, a radiation injury may be no more serious than a mild sunburn. In the most serious cases, radiation injury can cause death within a matter of hours.

Humans are exposed to ionizing radiation from a variety of sources. These sources fall into four general categories: natural, intentional, accidental, and therapeutic. Natural sources include sunlight and cosmic radiation. Sunlight includes not only visible light, which has relatively few health effects, and radiation of higher frequency, such as ultraviolet radiation. Just stepping outdoors exposes a person to IR in sunlight.

Cosmic rays are similar to sunlight in that they are always present around us. They are not visible, but they do contain ionizing radiation. Exposure to natural sources of IR account for a very small fraction of radiation injuries.

Intentional exposure to IR is rare. It occurs when nuclear weapons (hydrogen and atomic bombs) are used as weapons of war. This has occurred only twice in history, when the United States dropped atomic bombs on Hiroshima and Nagasaki, Japan, at the end of World War II. Many thousands of people were killed or injured by these attacks. They are the only people ever to have been injured by intentional exposure to IR.

Accidental exposure occurs when a person is exposed to IR by mistake. For example, radioactive elements are sometimes spilled in a research laboratory. Workers in the lab may be exposed to the IR from those elements.

Accidental exposure to IR has caused a number of radiation injuries and deaths. Between 1945 and 1987, there were 285 nuclear reactor accidents worldwide. More than fifteen hundred people were injured and sixty-four were killed in these accidents.

Therapeutic exposure to IR occurs during various medical procedures. Radioactive elements and ionizing radiation have many valuable applications in diagnosing and treating disorders. But those treatments can have harmful as well as beneficial effects on patients. The rate of radiation injuries due to this cause probably cannot be measured. Many people who may have been injured by a radiation treatment probably died of the condition for which they were being treated.

CAUSES

Radiation causes damage because it destroys chemicals in a cell. The cell loses its ability to function normally and dies.

Cells in tissues that are growing rapidly are more sensitive to radiation. For example, bone marrow cells in the center part of a bone are the fastest-growing

cells in the body. They are the most sensitive of all body cells to IR. The cells of a fetus are also growing very rapidly. They are also at high risk for damage from IR.

The sensitivity of various types of cells is shown below. The dose given in each case is the lowest amount of radiation that cells in the tissue can absorb without being damaged:

• Fetus: 2 Gy
• Bone marrow: 2 Gy
• Ovaries: 2–3 Gy
• Lens of the eye: 5 Gy
• A child's bone: 20 Gy
• An adult's bone: 60 Gy
• A child's muscle: 20–30 Gy
• An adult's muscle: 100 or more Gy

SYMPTOMS

A great deal of research was conducted on people who survived the atomic bomb explosions in Japan in 1945. From that research, we know what effect large doses of IR have on people. Those effects include:

• 1–2 Sv: Vomiting, loss of appetite, and generalized discomfort. These symptoms usually disappear in a short time.
• 2–6 Sv: Good chance for survival, provided the patient is given blood transfusions and antibiotics.
• 6–10 Sv: Massive destruction of bone marrow. If bone marrow is destroyed, the body cannot produce new blood cells. The patient usually dies in less than two months from infection or uncontrolled bleeding.
• 10–20 Sv: Destruction of intestinal tissue, causing serious digestive problems. The patient usually dies within three months from vomiting, diarrhea, infection, and starvation.
• More than 20 Sv: Massive damage to the nervous system and the circulatory (heart and blood vessels) system. The patient usually dies within a few days.

The most severe symptoms are very rare. They have been seen only in atomic bomb blasts and the most serious nuclear power plant accidents.

Far more commonly, doctors see symptoms of exposure to much lower levels of radiation. These symptoms most often appear in the form of cancer. Cancers (see cancer entry) develop when the number of cells damaged by IR gradually increases over time. Cells begin to grow out of control and spread throughout the body. Ionizing radiation is believed to be responsible for about 3 percent of all human cancers. The most common forms of cancer caused by IR are leukemia and cancers of the thyroid, brain, bone, breast, skin, stomach, and lungs (see breast cancer, leukemia, lung cancer, and skin cancer entries).

TREATMENT

Patients who have received more than about 10 Sv of radiation are unlikely to survive. No treatment is available for people in this group.

Patients who receive very low doses of IR are most likely to develop some form of cancer. When the cancer has developed, it is treated by the techniques usually used for cancers, such as chemotherapy, radiation, and surgery.

Patients who are exposed to about 1 to 6 Sv can benefit from medical treatment. One step usually involves the use of antibiotics to protect the patient against infection. The patient may also require a blood transfusion. In some cases, superficial damage to the skin can be treated with surgery. The damaged portion of skin is removed and replaced with a skin graft.

Alternative Treatment

There is much current interest in helpful chemicals called "free radical scavengers." It is not yet known how they work, but studies strongly suggest that diets full of free radical scavengers are beneficial. Free radical scavengers are also called antioxidants and include beta-carotene, vitamins E and C, and selenium. Beta-carotene is present in yellow and orange fruits and vegetables. Vitamin C is found in citrus fruits such as oranges.

CHERNOBYL

Nuclear power plants are normally constructed with very high levels of safety in mind and there is little or no evidence that humans are at risk as the result of the normal operation of a nuclear power plant. When damage occurs at the plant, however, the situation changes dramatically.

One such accident occurred in April 26, 1986, at the Chernobyl Plant outside Kiev in Ukraine in 1986. This was the most serious accident at a nuclear plant that the world has seen so far. The accident occured when an improperly conducted experiment in one of the reactors caused an explosion. The explosion blew off the top of the reactor, releasing 100 million curies of radionuclides into the atmosphere. More than thirty people who were at the site of the reactor when it exploded died immediately or shortly after the accident.

An area around the site with a 30-mile radius was evacuated. Since the accident doctors have found a striking increase of thyroid cancer among people, especially children, living in contaminated regions in Ukraine and Belarus.

Traditional Chinese medicine, acupuncture, and herbal medicines may help in recovery from radiation injuries.

PROGNOSIS

The prognosis for radiation injuries depends strongly on the amount of IR received by the patient. People who have been exposed to more than 10 Sv stand little or no chance of survival. People who have received a dose of 1 to 10 Sv may survive, provided they receive prompt treatment with antibiotics and blood transfusions, where needed. People who develop cancers as the result of low exposure to radiation have the same prognosis as those who develop the same cancers for other reasons.

PREVENTION

There is no way to protect against radiation injuries caused by natural radiation. Some natural radiation reaches us even if we never leave our homes. Injuries caused by intentional exposure can be prevented, of course, by avoiding the use of nuclear weapons, such as atomic and hydrogen bombs.

Accidental exposure to radiation is difficult to avoid. Facilities where radiation is present, as in nuclear power plants, have developed safety measures to protect workers against exposure to IR. In most cases, these measures are very effective. However, it is impossible to prevent all accidents. When those accidents occur, some workers are likely to be exposed to IR and develop radiation injuries.

Exposure to IR during therapeutic procedures can always be avoided. A person can choose not to have the procedure, thereby avoiding exposure to the radiation. But in the vast majority of cases, the potential benefits of the procedure are greater than the potential risks. People choose to be treated with radiation because it is likely to help them get better or live longer. The careful use of equipment to protect healthy parts of the body is probably the best guarantee against radiation injuries due to therapeutic procedures.

FOR MORE INFORMATION

Books

Lebaron, Wayne. Preparation for Nuclear Disaster. Commack, NY: Nova Science Publishers, Inc., 1998.

Murphy, Jack, et al. Nuclear Medicine. New York: Chelsea House Publishers, 1993.

Web sites

"Radiation Injuries." [Online] http://www.ohsu.edu/cliniweb/C21C21.866.733.html (accessed on October 31, 1999).

Radiation Injuries

Definition

Radiation injury, also known as radiation sickness, results from exposure to excessive radiation. The seriousness of the condition depends on the type of radiation, amount of radiation, length of exposure time, and the part of the body affected. Radiation can be defined as the process of emitting energy in the form of particles or waves. Radiation is emitted by atoms in the process of changing, whether the atomic action is a naturally occurring or humanly directed process.

Description

Found throughout the universe, radiation comes in many forms. The better known forms of radiation include light, television and radio waves, microwaves, and radar, which generally do not cause injury. There are a number of potentially damaging forms of radiation including, for example, x rays, gamma rays, the energy emitted by radioactive substances such as uranium, and the radiation generated during nuclear reactions. Perhaps the most infamous events associated with widespread radiation injury and sickness occurred during the atomic bombing of Hiroshima and Nagasaki, Japan, which helped bring about the end of World War II, and the more recent nuclear meltdown at Chernobyl in 1986.

Radiation exposure can occur as a single large exposure, referred to as acute; or as a series of small exposures over time, referred to as chronic. Radiation sickness is generally associated with acute exposure. Chronic exposure is usually associated with delayed medical problems such as cancer and premature aging.

Radiation can cause damage by separating molecules into electrically charged particles, a process known as ionization. Some forms of ionizing radiation include cosmic rays, gamma rays, and x rays. Ionizing radiation damages deoxyribonucleic acid (DNA), which causes genetic mutation.

Several units of measure are used to quantify radiation energy. The roentgen, named after Wilhelm Conrad Roentgen, who discovered x rays in 1895, measures ionizing energy in air. A rad (short for radiation) indicates the transferred absorbed dose. The rem (taken from "Roentgen equivalent man") measures tissue response.

A roentgen generates approximately one rad of effect, producing approximately one rem of response. The gray and the sievert are international units equivalent to 100 rads and rems, respectively. A curie, named after the French physicists (Pierre and Marie Curie) who first began working with radiation, is a measure of radioactivity given off by a radioactive element. The average annual human exposure to natural background radiation is roughly 3 milliSieverts (mSv).

Radiation is pervasive. For example, the sun generates cosmic rays, and there are traces of radioactive elements in the air (radon), as well as in the Earth (uranium and radium, among others). Any amount of ionizing radiation will produce some damage.

Although the earth's atmosphere protects us from most of the sun's radiation, living at 5,000 ft (1,700 m) altitude in, for example, Denver, Colorado, doubles the exposure to radiation; and a flight in a commercial airliner increases it 150-fold.

Ionizing radiation is used for medical diagnosis and treatment, most commonly in the form of x rays and CT scans. Nuclear medicine employs radioactive isotopes to diagnose and treat medical conditions. Radioactive elements localize to specific tissues, giving off tiny amounts of radiation. Detecting that radiation provides anatomical and functional information. Radioactive chemicals are also used in the treatment of certain conditions, most common of which is the overactive thyroid. Because the thyroid is the only gland that utilizes iodine, all iodine in the body is concentrated there. A radioactive isotope of iodine (I-131) will gradually destroy overactive thyroid tissue.

Before the potential dangers posed by excessive radiation exposure were known, those who first began working with x rays frequently died from its long-term effects, most commonly leukemia. Doses now used for medical examinations are ordinarily too small to be of concern. Methods of magnification, lead shielding, and a greater awareness of the risks have nearly eliminated the danger from diagnostic radiation. However, no level of exposure is completely safe.

It is believed that radiation is responsible for less than 1% of all human disease and for approximately 3% of all cancers. This figure does not include lung cancer from environmental radon, which is difficult to determine because such effects are confounded by tobacco's similar effects. Because cancers are usually faster growing than their host tissues, they can be selectively killed by carefully measured radiation. This is most true of the lymphomas. Other cancers are less radiosensitive. Whenever radiation is used to treat cancer, care must be taken to measure the dose and aim it accurately. Even so, many cancers differ so little from the surrounding tissue that undesirable damage is unavoidable.

Newer techniques of directing radiation now provide greater safety. The gamma knife is a new surgical tool that focuses radiation with a high degree of accuracy in three dimensions, sparing surrounding tissue from radiation injury.

Causes and symptoms

Radiation damage depends upon the amount of radiation, the time over which it is absorbed, and the susceptibility of the tissue. The fastest-growing tissues are the most vulnerable, because radiation as much as triples its effects during the growth phase. Bone marrow cells that produce blood are the fastest-growing cells. Fetuses are also extremely vulnerable. Germinal cells in the testes and ovaries may be rendered useless by very small doses of radiation. More resistant cells include those of the skin. Brain cells are most resistant because they grow the slowest.

The most common symptoms of radiation sickness include:

• nausea and vomiting
• diarrhea
• skin burns (redness, blistering)
• weakness, fatigue, exhaustion, fainting
• dehydration
• inflammation of areas (redness, tenderness, swelling, bleeding)
• hair loss
• ulceration of the oral mucosa
• ulceration of the esophagus and gastrointestinal system
• vomiting blood
• bloody stool
• bleeding from the nose, mouth, gums, and rectum
• bruising
• sloughing of skin
• open sores on the skin

Exposure over time causes accumulating damage, which if not sufficient to kill cells, distorts their growth and causes scarring and cancers. In addition to leukemia, cancers of the thyroid, brain, bone, breast, skin, stomach, and lung are more likely to occur.

Mortality and morbidity risk are dictated by the total dose absorbed.

• Massive doses incinerate tissue immediately.
• A sudden whole-body dose over 50 Sv produces such profound neurological, heart, and circulatory damage that patients die within two days.
• Doses in the 10-20 Sv range strip intestinal lining and lead to death within three months from vomiting, diarrhea, starvation, and infection.
• Victims receiving 6-10 Sv all at once usually experience bone marrow failure and death within two months, due to loss of blood coagulation factors and the protection against infection provided by white blood cells.
• Those exposed to 2-6 Sv may survive if they are treated with blood transfusions and antibiotics.
• One or 2 Sv produces a brief, non-lethal sickness with vomiting, loss of appetite, and generalized discomfort.

Treatment

It is important to ascertain the dose received as early as possible, so that attention can be directed to those victims in the 2-10 Sv range who might survive with treatment. Blood transfusions, protection from infection, and possibly the use of blood formation stimulants save many victims in this category.

Radiation exposure usually damages the skin and requires careful wound care, dead tissue removal, and possible skin grafting. Infection control is imperative.

Alternative treatment

Studies strongly suggest that diets rich in free radical scavengers, also known as antioxidants, are recommended. The more commonly recommended antioxidants include beta-carotene, vitamins E and C, and the trace mineral selenium. Beta-carotene is present in yellow and orange fruits and vegetables. Vitamin C can be found in citrus fruits. Traditional Chinese medicine (TCM) and acupuncture, botanical medicine, and homeopathy all have contributions to make to recovery from radiation injuries.

Prognosis

Prognosis depends on the amount of exposure to radiation and the corresponding level of injury. High doses of radiation can be fatal, and minimal exposure can have virtually no effect. Some exposures may affect victims later in life, in the form of slow-growing cancers or reproductive difficulties.

Health care team roles

Physicians diagnose and treat radiation injuries. Nurses administer appropriate medications and otherwise supervise patient care. X-ray technologists can help prevent radiation exposure to themselves and to their patients by making sure equipment is proper working order and that appropriate preventative measures, such as the use of shields and radiation badges, are taken.

KEY TERMS

DNA— Deoxyribonucleic acid.

Gonad— Testes (males); ovaries (women).

Isotope— An unstable form of an element that emits radiation.

Resources

BOOKS

Dowd, S., E. Tilson, and A. Allen. Practical Radiation Protection and Applied Radiobiology, 5th ed. New York: Harcourt Brace & Co., 1999.

Fauci, Anthony S., et al., eds. Harrison's Principles of Internal Medicine, 14th ed. New York: McGraw-Hill, 1998.

Upton, Arthur C. "Radiation Injury." In Cecil Textbook of Medicine, ed. J. Claude Bennett and Fred Plum. Philadelphia: W. B. Saunders, 1996.

Walker, J. S. Permissable Dose: A History of Radiation Protection in the Twentieth Century. Berkeley, CA: University of California Press, 2000.