Radiation poisoning is a rare but challenging condition. Dependence on nuclear energy and the expanded use of radioactive isotopes in industry and medicine have increased the possibility of accidental exposures. Ionizing radiation is generated from a variety of sources. Particle-emitting sources produce beta and alpha particles and neutrons. Ionizing electromagnetic radiation includes gamma rays and x-rays. In contrast, magnetic fields, microwaves, radiofrequency waves, and ultrasound are examples of nonionizing electromagnetic radiation.

Management of a radiation accident depends on whether the victim is irradiated or contaminated. Irradiated victims pose no threat to the treating health care provider and can be managed without special precautions. In contrast, contaminated victims must be decontaminated to prevent the spread of radioactive materials to others and the environment.

A terrorist “dirty bomb” (dispersion bomb) will likely contain commonly acquired radioactive materials such as the following: americium (alpha emitter, found in smoke detectors and oil exploration equipment); cobalt (gamma emitter, used in food and mail irradiation); iridium (gamma emitter, used in cancer therapy); strontium (gamma emitter, used in medical treatment and power generation); and cesium (gamma emitter, used to sterilize medical equipment and for medical and industrial uses). Psychological effects (eg, panic) may overshadow medical concerns because significant acute radiation exposure by contamination is generally confined to the immediate blast area. Long-term exposure may increase the risk for cancer while adequate decontamination can be problematic, potentially making the blast area uninhabitable.

1. Radiation impairs biological function by ionizing atoms and breaking chemical bonds. Consequently, the formation of highly reactive free radicals can damage cell walls, organelles, and DNA. Affected cells are either killed or inhibited in division. Cells with a high turnover rate (eg, bone marrow and epithelial coverings of skin, GI tract, and pulmonary system) are more sensitive to radiation. Lymphocytes are particularly sensitive.
2. Radiation causes a poorly understood inflammatory response and microvascular effects after moderately high doses (eg, 600 rad).
3. Radiation effects may be deterministic or stochastic. Deterministic effects are dose related and usually occur within an acute time frame (within a year). Stochastic effects have no known threshold and may occur after a latency period of years (eg, cancer).

1. Gray (Gy) is the unit of radiation dose commonly referred to in exposures, whereas Sievert (Sv) is useful in describing dose-equivalent biological damage. For most exposures, these units can be considered interchangeable. The exception is alpha particle exposure (eg, plutonium), which causes greater double-stranded DNA damage and a higher Sievert compared with Gray.
2. Note: The International System of Units (SI units) has replaced the old “rad” and “rem” nomenclature. For conversion purposes, 1 gray (Gy) = 100 rad and 1 sievert (Sv) = 100 rem.
3. Toxicity thresholds
   1. Acute effects. Exposure over 0.75 Gy (75 rad) causes nausea and vomiting. Exposure over 4 Gy (400 rad) is potentially lethal without medical intervention. Vomiting within 1-5 hours of exposure suggests an exposure of at least 6 Gy (600 rad). Brief exposure to 50 Gy (5,000 rad) or more usually causes death within minutes to hours.
   2. Carcinogenesis. Radiation protection organizations have not agreed on a threshold dose for stochastic effects, such as cancer.
4. Recommended exposure limits
   1. Exposure to the general population. The National Council on Radiation Protection (NCRP) recommends a maximum of 5 milliSieverts (500 millirem) per person per year. The background radiation at sea level is about 0.35 mSv (35 mrem) per year.
   2. Diagnostic x-rays. The current US exposure standards are set at 50 mSv per year to the total body, gonads, or blood-forming organs and 750 mSv/y to the hands or feet. For comparison, a single chest radiograph results in radiation exposure to the patient of about 0.15 mSv (but only about 0.00006 mSv to nearby health care personnel at a distance of 160 cm). A CT scan exposes the head to about 2 mSv; an abdominal CT scan may expose that region to as much as 10-20 mSv.
   3. Radiation during pregnancy. Guidelines vary but generally recommend a maximum exposure of no more than 0.5 mSv per month. Exposure to the ovaries and fetus from a routine abdominal (KUB) film may be as high as 1.5 mSv, whereas the dose from a chest radiograph is about 0.15 mSv.
   4. Exposure guidelines for emergency health care personnel. To save a life, the NCRP recommends a maximum whole-body exposure of 500-750 mSv for a rescuer.

1. Acute radiation syndrome (ARS) consists of a constellation of symptoms and signs indicative of systemic radiation injury. It is described in four stages (prodrome, latency, manifest illness, and recovery). The onset and severity of each stage of radiation poisoning are determined largely by the dose.
   1. The prodromal stage, from 0 to 48 hours, may include nausea, vomiting, abdominal cramps, and diarrhea. Severe exposures are associated with diaphoresis, disorientation, fever, ataxia, coma, shock, and death.
   2. During the latent stage, symptoms may improve. The duration of this stage varies from hours to days, but it may be shorter or absent with massive exposures.
   3. The manifest illness stage, from 1 to 60 days, is characterized by multiple-organ system involvement, particularly bone marrow suppression, which may lead to sepsis and death.
   4. The recovery phase may be accompanied by hair loss, disfiguring burns, and scars.
2. Gastrointestinal system. Exposure to 1 Gy or more usually produces nausea, vomiting, abdominal cramps, and diarrhea within a few hours. After exposure to 6 Gy or more, loss of integrity of the GI mucosal layer results in denudation and severe necrotic gastroenteritis. The clinical picture may include marked dehydration, GI bleeding, and death within a few days. Doses of 15 Gy are believed to destroy GI stem cells completely.
3. Central nervous system. Acute exposures of 20-50 Gy may produce confusion and stupor, followed within minutes to hours by ataxia, convulsions, coma, and death. In animal models of massive exposure, a phenomenon known as “early transient incapacitation” occurs.
4. Hematologic system. Bone marrow depression may be subclinical but apparent on a CBC after exposure to as little as 0.3 Gy. Immunocompromise usually follows exposure to more than 1 Gy.
   1. Early neutropenia is caused by margination; the true nadir occurs at about 30 days or as soon as 14 days after severe exposure. Neutropenia is the most significant factor in septicemia.
   2. Thrombocytopenia is usually not evident for 2 weeks or more after exposure.
   3. The lymphocyte count is of great prognostic importance and usually reaches a nadir within 48 hours of severe exposure. A lymphocyte count of less than 300-500/mm³ during this period indicates a poor prognosis, whereas 1,200/mm³ or more suggests likely survival.
5. Other complications of high-dose acute radiation syndrome include multiple-organ system failure, veno-occlusive disease of the liver, interstitial pneumonitis, renal failure, tissue fibrosis, skin burns, and hair loss.

Depends on the history of exposure. The potential for contamination should be assessed by determining the type of radionuclide involved and the potential route(s) of exposure.

1. Specific levels
   1. Detection. Depending on the circumstances, the presence of radionuclides may be verified by one or more of the following devices: survey meters with pancake or alpha probes, whole-body counts, chest counts, and nuclear medicine cameras.
   2. Biological specimens. Nasopharyngeal and wound swabs, sputum, vomitus, skin wipes, wound bandages, and clothing articles (particularly shoes) may be collected for radionuclide analysis and counts. Collection of urine and feces for 24-72 hours may assist in the estimation of an internal dose. Serum levels of radioactive materials are not generally available or clinically useful.
   3. Other methods. Chromosomal changes in lymphocytes are the most sensitive indication of exposures to as little as 0.1 Gy; DNA fragments, dicentric rings, and deletions may be present. Exposure to 0.15 Gy may cause oligospermia, first seen about 45 days after the exposure.
2. Other useful laboratory studies include CBC (repeat every 6 hours), electrolytes, glucose, BUN, creatinine, and urinalysis. Immediately draw lymphocytes for human leukocyte antigen (HLA) typing in case bone marrow transplant is required later.

The Radiation Emergency Assistance Center and Training Site (REAC/TS) provides incident response and consultation to physicians 24 hours a day, 7 days a week on managing the medical component of a radiation incident. The website is https://orise.orau.gov/reacts/. During regular office hours, call 1-865-576-3131, or call 1-865-576-1005 after office hours or at any time for immediate assistance. REAC/TS is operated for the US Department of Energy (DOE) by the Oak Ridge Associated Universities (ORAU). Also contact the local or state agency responsible for radiation safety.

1. Emergency and supportive measures. Depending on the risk to the rescuers, treatment of serious medical problems takes precedence over radiologic concerns. If there is a potential for contamination of rescuers and equipment, appropriate radiation response protocols should be implemented, and rescuers should wear protective clothing and respirators. Note: If the exposure was to electromagnetic radiation only, the victim is not contaminating and does not pose a risk to any downstream personnel.
   1. Maintain an open airway and assist ventilation if necessary.
   2. Treat coma and seizures if they occur.
   3. Replace fluid losses from gastroenteritis with IV crystalloid solutions.
   4. Treat leukopenia and resulting infections as needed. Immunosuppressed patients require reverse isolation and appropriate broad-spectrum antibiotic therapy. Bone marrow stimulants may help selected patients.
2. Specific drugs and antidotes. Chelating agents or pharmacologic blocking drugs may be useful in some cases of ingestion or inhalation of certain biologically active radioactive materials if they are given before or shortly after exposure (Table II-54). Contact REAC/TS (see above) for specific advice on the use of these agents.
3. Decontamination
   1. Exposure to particle-emitting solids or liquids.The victim is potentially highly contaminating to rescuers, transport vehicles, and attending health personnel.
      1. Remove victims from exposure, and if their condition permits, remove all contaminated clothing and wash the victims with soap and water.
      2. All clothing and cleansing water must be saved, evaluated for radioactivity, and disposed of properly.
      3. Rescuers should wear protective clothing and respiratory gear to avoid contamination. At the hospital, measures must be taken to prevent contamination of facilities and personnel (see Section IV).
      4. Induce vomiting or perform gastric lavage if radioactive material has been ingested. Administer activated charcoal, although its effectiveness is unknown. Certain other adsorbent materials may also be effective (see Table II-54).
      5. Contact REAC/TS (see above) and the state radiologic health department for further advice. In some exposures, unusually aggressive steps may be needed (eg, lung lavage for significant inhalation of plutonium).
   2. Electromagnetic radiation exposure.The patient is not radioactive and does not pose a contamination threat. There is no need for decontamination once the patient has been removed from the source of exposure unless electromagnetic radiation emitter fragments are embedded in body tissues.
4. Enhanced elimination. Chelating agents and forced diuresis may be useful for certain exposures (see Table II-54).