Symptoms

The severity of signs and symptoms of radiation sickness depends on how much radiation you've absorbed. How much you absorb depends on the strength of the radiated energy and the distance between you and the source of radiation.

Absorbed dose and duration of exposure The absorbed dose of radiation is measured in a unit called a gray (Gy). Diagnostic tests that use radiation, such as an X-ray, result in a small dose of radiation — typically well below 0.1 Gy, focused on a few organs or small amount of tissue.

Signs and symptoms of radiation sickness usually appear when the entire body receives an absorbed dose of at least 1 Gy. Doses greater than 6 Gy to the whole body are generally not treatable and usually lead to death within two days to two weeks, depending on the dose and duration of the exposure.

Initial signs and symptoms The initial signs and symptoms of treatable radiation sickness are usually nausea and vomiting. The amount of time between exposure and when these symptoms develop is an indicator of how much radiation a person has absorbed.

After the first round of signs and symptoms, a person with radiation sickness may have a brief period with no apparent illness, followed by the onset of new, more serious symptoms.

In general, the greater your radiation exposure, the more rapid and more severe your symptoms will be.

Source: Adapted from "Bushberg JT. Radiation exposure and contamination. The Merck Manuals: The Merck Manual for Healthcare Professionals" and "Upton AC. Radiation injury. In: Goldman L, et al., eds. Cecil Medicine. 23rd ed. Philadelphia, Pa.: Saunders Elsevier; 2007."

When to see a doctor An accident or attack that causes radiation sickness would no doubt cause a lot of attention and public concern. If an event occurs, monitor radio, television or online reports to learn about emergency instructions for your area.

If you know you've been exposed to radiation, seek emergency medical care.

Causes

Radiation is the energy released from atoms as either a wave or a tiny particle of matter. Radiation sickness is caused by exposure to a high dose of radiation, such as a high dose of radiation received during an industrial accident. Common exposures to low-dose radiation, such as X-ray examinations, do not cause radiation sickness.

Sources of high-dose radiation Possible sources of high-dose radiation include the following:

• An accident at a nuclear industrial facility
• An attack on a nuclear industrial facility
• Detonation of a small radioactive device
• Detonation of a conventional explosive device that disperses radioactive material (dirty bomb)
• Detonation of a standard nuclear weapon

Radiation sickness occurs when high-energy radiation damages or destroys certain cells in your body. Regions of the body most vulnerable to high-energy radiation are cells in the lining of your intestinal tract, including your stomach, and the blood cell-producing cells of bone marrow.

Complications

Radiation sickness itself doesn't cause long-term medical problems for those who survive the illness. However, the radiation exposure that caused the immediate radiation sickness does significantly increase a person's risk of developing cancer later in life.

Having radiation sickness could also contribute to both short-term and long-term mental health problems, such as grief, fear and anxiety about:

• Experiencing a radioactive accident or attack
• Mourning friends or family who haven't survived
• Dealing with the uncertainty of a mysterious and potentially fatal illness
• Worrying about the eventual risk of cancer due to radiation exposure

Tests and diagnosis

When a person has experienced known or probable exposure to a high dose of radiation from an accident or attack, medical personnel take a number of steps to determine the absorbed radiation dose. This information is essential for determining how severe the illness is likely to be, which treatments to use and whether a person is likely to survive.

Information important for determining an absorbed dose includes:

• Known exposure. Details about distance from the source of radiation and duration of exposure can help provide a rough estimate of the severity of radiation sickness.
• Vomiting and other symptoms. The time between radiation exposure and the onset of vomiting is a fairly accurate screening tool to estimate absorbed radiation dose. The shorter the time before the onset of this sign, the higher the dose is. The severity and timing of other signs and symptoms may also help medical personnel determine the absorbed dose.
• Blood tests. Frequent blood tests over several days enable medical personnel to look for drops in disease-fighting white blood cells and abnormal changes in the DNA of blood cells. These factors indicate the degree of bone marrow damage, which is determined by the level of an absorbed dose.
• Dosimeter. A device called a dosimeter can measure the absorbed dose of radiation but only if it was exposed to the same radiation event as the affected person.
• Survey meter. A device such as a Geiger counter can be used to survey people to determine the body location of radioactive particles.
• Type of radiation. A part of the larger emergency response to a radioactive accident or attack would include identifying the type of radiation people have been exposed to. This information would guide some decisions for treating people with radiation sickness.

Treatments and drugs

Radiation sickness treatment is aimed at preventing further radioactive contamination, managing organ damage, reducing symptoms and managing pain.

Decontamination This phase of radiation sickness treatment removes external radioactive particles to the greatest extent possible. Removing clothing and shoes eliminates about 90 percent of external contamination. Gently washing with water and soap removes additional radiation particles from the skin.

Decontamination at the start of radiation sickness treatment prevents further distribution of radioactive materials and lowers the risk of internal contamination from inhalation, ingestion or open wounds.

Treatment for damaged bone marrow A protein called granulocyte colony-stimulating factor, which promotes the growth of white blood cells, is used in radiation sickness treatment to counter bone marrow damage. This protein-based medication, which includes filgrastim (Neupogen) and pegfilgrastim (Neulasta), may increase white blood cell production and help prevent subsequent infections.

If you have severe damage to bone marrow, radiation sickness treatment may also include transfusions of red blood cells or blood platelets.

Treatment for internal contamination Some radiation sickness treatments may reduce organ damage caused by radioactive particles. Medical personnel would use these treatments only if you've been exposed to a specific type of radiation. These treatments include the following:

• Potassium iodide. This is a nonradioactive form of iodine. Because iodine is essential for proper thyroid function, the thyroid becomes a "destination" for iodine in the body. If you have internal contamination with radioactive iodine (radioiodine), your thyroid will absorb radioiodine just as it would other forms of iodine. Treatment with potassium iodide may fill "vacancies" in the thyroid and prevent absorption of radioiodine. The radioiodine is eventually cleared from the body in urine.
• Prussian blue. This type of dye binds to particles of radioactive elements known as cesium and thallium. The radioactive particles are then excreted in feces. This treatment speeds up the elimination of the radioactive particles and reduces the amount of radiation cells may absorb.
• Diethylenetriamine pentaacetic acid (DTPA). This substance binds to metals. DTPA binds to particles of the radioactive elements plutonium, americium and curium. The radioactive particles pass out of the body in urine, thereby reducing the amount of radiation absorbed.

Supportive treatment If you have radiation sickness, you may receive additional medications or interventions to treat:

• Bacterial infections
• Headache
• Fever
• Diarrhea
• Nausea and vomiting
• Dehydration

End-of-life care A person who has absorbed large doses of radiation (6 Gy or greater) has little chance of recovery. Depending on the severity of illness, death can occur within two days or two weeks. People with a lethal radiation dose will receive medications to control pain, nausea, vomiting and diarrhea. They may also benefit from psychological or pastoral care.