Weapons of Terror: Nuclear Radiation Exposure

Nuclear Radiation Exposure

The threat of nuclear warfare or radiation exposure is very real with the availability of nuclear material and easily concealed sim-ple devices, such as the so-called dirty bomb, for dispersal. A dirty bomb is a conventional explosive (eg, dynamite) that is packaged with radioactive material that scatters when the bomb is deto-nated. It disperses radioactive material and may be called a radi-ologic weapon, but is not a nuclear weapon, which is a complex nuclear fission reaction that is thousands of times more devastat-ing than the dirty bomb.

Sources of radioactive material include not only nuclear weapons but reactors and simple radioactive samples, such as weapons-grade plutonium or uranium, freshly spent nuclear fuel, or medical supplies (eg, radium, certain cesium isotopes) used in cancer treatments and radiography machines. Exposure of a large number of people can be accomplished by placing a radioactive sample in a public place. Thousands may be exposed this way; some may be immediately affected, and others may require health monitoring for many years to assess long-term effects.

History has demonstrated the effectiveness of these weapons in the devastating results of the bombings of Hiroshima and Nagasaki in World War II. The effects of radiation exposure also were felt by the inhabitants of a small town in Brazil, who in 1987 found and opened a small canister of cesium 137 and rubbed the blue powder on themselves; 249 people were sickened, and 4 died

Jagminas & Suner, 2001). In 1983, a hospital sample was stolen in Mexico, resulting in the release of radioactive material among some scrap metal. A year later, the radiation contamination was de-tected when the scrap metal was inadvertently transported into the Los Alamos National Laboratory and triggered a Geiger counter.

On a larger scale, nuclear reactor incidents have occurred in the Chernobyl (1986) and Three Mile Island (1979) nuclear fa-cilities. There were 31 official deaths on the day of the Chernobyl incident, which involved a core meltdown and explosion, releas-ing radiation throughout the community. The long-term effects of this incident, including increased incidence of thyroid cancers and leukemia, continue to be evaluated. Reactors, however, fol-low very strict security measures and protocols for prevention of core meltdown. These measures decrease the possibility of a ra-diation incident from a reactor.

TYPES OF RADIATION

Atoms consist of protons, neutrons, and electrons. The protons and neutrons are in balance in the nucleus. The protons repel each other, because they are all positively charged. The number of protons is specific for each element in the periodic table. There is a specific ratio of protons and neutrons for each different atom, and the result is element stability. When an element is radio-active, there is an imbalance in the nucleus resulting from an excess of neutrons.

To achieve stability, a radioactive nuclide can eject particles until the most stable number (an even number) of protons and neutrons exists. A proton can become a neutron by ejecting a positron; conversely, a neutron can become a proton by ejecting a negative electron. An alpha particle is released when two pro-tons and two electrons are ejected.

Alpha particles cannot penetrate the skin. A thin layer of paper or clothing is all that is necessary to protect the skin from alpha-radiation. However, this low-level radiation can enter the body through inhalation, ingestion, or injection (open wound).

Only localized damage will occur.

Beta particles have the ability to moderately penetrate the skin to the layer in which skin cells are being produced. This high-energy radiation can cause skin damage if the skin is exposed for a prolonged period and can cause injury if beta particles become internal by penetrating the skin.

Gamma-radiation is a short-wavelength electromagnetic en-ergy that is emitted when there is excess core nucleus energy. Gamma particles are penetrating. It is difficult to shield against gamma-radiation. X-rays are an example of gamma-radiation. Gamma-radiation often accompanies both alpha- and beta-particle emission.

MEASUREMENT AND DETECTION

Radiation is measured in several different units. The rad is the basic unit of measurement. A rad is equivalent to 0.01 joule of energy per kilogram of tissue. To determine the damaging effect of the rad, a conversion to the rem (Roentgen equivalent man) is necessary. The rem reflects the type of radiation absorbed and the potential for damage. For example, 200,000 mrem will result in mild radiation sickness (1 rem = 1000 millirem) ( Jagminas& Suner, 2001). Typical natural yearly exposure for an individual is 360 mrem. Another important concept is half-life. The half-life of a radioactive product is the time it takes to lose one half of its radioactivity.

Radiation is invisible. The only means of detection is through a device that determines the exposure per minute. There are var-ious devices for this purpose. The Geiger counter (or Geiger-Mueller survey meter) can measure background radiation quickly through detection of gamma- and some beta-radiation. With high-level radiation, the Geiger counter may underestimate exposure. Other devices include the ionization chamber survey meter, alpha monitors, and dose-rate meters. Personal dosimeters are simple tools to identify radiation exposure and are worn by radiology personnel.

EXPOSURE

Exposure is affected by time, distance, and shielding. The longer a person is within the radiation area, the higher the exposure. Also, the larger the amount of radioactive material in the area, the greater the exposure. The farther away the person is from the ra-diation source, the lower the exposure. Shielding from the radia-tion source also decreases exposure. One should never touch radioactive materials directly.

Three types of radiation-induced injury can occur: external ir-radiation, contamination with radioactive materials, and incor-poration of radioactive material into body cells, tissues, or organs.

External irradiation exposure occurs when all or part of thebody is exposed to radiation that penetrates or passes completely through the body. In this type of exposure, the patient is not radioactive and does not require special isolation or decontami-nation measures. Irradiation does not necessarily constitute a medical emergency.

Contamination occurs when the body is exposed to radioactivegases, liquids, or solids either externally or internally. If internal, the contaminant can be deposited within the body. Contamination requires immediate medical management to prevent incorporation.

Incorporation is the actual uptake of radioactive material intothe cells, tissues, and susceptible organs. The organs involved are usually the kidneys, bone, liver, and thyroid.

Sequelae of contamination and incorporation can occur days to years later. The thyroid gland can be largely protected from radiation exposure by administration of stable iodine (potassium iodide, or KI) before or promptly after the intake of radioactive iodine (WHO, 1999).

Priorities in the treatment of any type of radiation exposure are always treatment of life-threatening injuries and illnesses first, followed by measures to limit exposure, contamination control, and finally decontamination.

DECONTAMINATION

Hospital and countywide disaster plans should be in effect when managing a radiation disaster. Access restriction is essential to prevent contamination of other areas of the hospital. Triage out-side the hospital is the most effective means of preventing conta-mination of the facility itself. Floors are covered to prevent tracking of contaminants throughout the treatment areas. Strict isolation precautions should be in effect. Waste is controlled through double-bagging and the use of plastic-lined containers outside of the facility.

Staff are required to wear protective clothing, such as water-resistant gowns, two pairs of gloves, masks, caps, goggles, and booties. Dosimetry devices should be worn by all staff members participating in patient care. The radiation safety officer in the hospital should be notified immediately to assist with surveys (using a radiation survey meter) of the incoming patients and to provide dosimeters to all staff personnel involved with patient care of exposed victims. There is minimal risk to staff if the pa-tients are properly surveyed and decontaminated. The majority of patients can be safely decontaminated with soap and water.

Each patient arriving at the hospital should be first surveyed with the radiation survey meter for external contamination and then directed toward the decontamination area as needed. De-contamination occurs outside of the ED with a shower, collec-tion pool, tarp, and collection containers for patient belongings, as well as soap, towels, and disposable paper gowns for patients. Water runoff needs to be contained. Patients who are uninjured can perform self-decontamination with the use of handheld showers. After the patient has showered, a resurvey should be conducted to determine whether the radioactive contaminants have been removed. Additional washings should occur until the patient is free of contamination. It is important to ensure during showers that previously clean areas are not contaminated with runoff from the washed contaminated areas (eg, hair should be washed in the bent-over position to protect the body from contamination).

Biologic samples should be taken through nasal and throat swabs, and a complete blood count with differential should be obtained. Wounds should be irrigated and then covered with a water-resistant dressing prior to total body decontamination.

Internal contamination or incorporation requires decontami-nation through catharsis and/or gastric lavage with chelating agents (agents that bind with radioactive substances and are then excreted). Samples of urine, feces, and vomitus are surveyed to determine internal contamination levels.

ACUTE RADIATION SYNDROME

Acute radiation syndrome (ARS) can occur after exposure to ra-diation. It is the dose rather than the source that determines whether ARS develops. Factors that determine whether the pa-tient’s response to exposure will result in ARS include a high dose (minimum 100 rad) and rate of radiation with total body expo-sure and penetrating-type radiation. Age, medical history, and genetics also affect the outcome after exposure. The effects follow a predictable course. Table 72-4 identifies the phases of ARS.

Each body system is affected differently in ARS. Systems with cells that rapidly reproduce are the most affected. The effects on the hematopoietic system include decreased numbers of lympho-cytes, granulocytes, thrombocytes, and reticulocytes. It is the first system affected and serves as an indicator of the severity of radi-ation exposure ( Jarrett, 2001; Jagminas & Suner, 2001). A marker of outcome is the absolute lymphocyte count at 48 hours after ex-posure. A significant exposure would be indicated by lymphocyte counts of 300 to 1200 per cubic millimeter of blood (the normal lymphocyte count is 1500 to 3000/mm³). Barrier precautions should be implemented to protect the patient from infection. Neutrophils decrease within 1 week, platelets decrease within 2 weeks, and red blood cells decrease within 3 weeks. Hemor-rhagic complications, fever, and sepsis are common.

The gastrointestinal system, with its rapidly producing cells, is also readily affected by radiation. Doses of radiation required to produce symptoms are approximately 600 rad or higherJagminas & Suner, 2001). The gastrointestinal symptoms usu-ally occur at the same time as the changes in the hematopoietic system. Nausea and vomiting occur within 2 hours after expo-sure. Sepsis, fluid and electrolyte imbalance, and opportunistic infections can occur as complications. An ominous sign is the presence of high fever and bloody diarrhea; these typically appear on day 10 after exposure.

The central nervous system is affected with doses greater than 1000 rad ( Jagminas& Suner, 2001). The symptoms occur when damage to the blood vessels of the brain results in fluid leakage. Signs and symptoms include cerebral edema, nausea, vomiting, headache, and increased intracranial pressure. Increased intra-cranial pressure heralds a poor outcome and imminent death. Central nervous system injury with this amount of exposure is ir-reversible and occurs before hematopoietic or gastrointestinal sys-tem symptoms appear. Cardiovascular collapse is usually seen in conjunction with these injuries.

Depending on the dose, skin effects can also occur. With ex-posure of 600 to 1000 rad, erythema occurs; it can disappear within hours, and then reappear. The exposed patient must be evaluated hourly for the presence of erythema. With exposures greater than 1000 rad, desquamation (radiation dermatitis) of the skin occurs. Necrosis becomes evident within a few days to months at doses greater than 5000 rad. Skin signs are an indication of the dose of radiation exposure.

Secondary injury can occur when the radiation exposure oc-curs during a traumatic event such as a blast or burn. Trauma in addition to radiation exposure increases patient mortality. Atten-tion must first be directed toward the primary assessment for trauma. Airway, breathing, circulation, and fracture reduction re-quire immediate attention. All definitive treatments must occur within the first 48 hours. Thereafter, all surgical procedures should be delayed for 2 to 3 months because of the potential for delayed wound healing and the possible development of oppor-tunistic infections several weeks after exposure.

SURVIVAL

There are three categories of predicted survival after radiation ex-posure: probable, possible, and improbable. Triage of victims at the scene, after decontamination, is conducted with the routine system for disaster triage. Presenting signs and symptoms deter-mine the potential for survival and therefore the category of pre-dicted survival during triage.

Probable survival victims have either no initial symptoms or only minimal symptoms (eg, nausea and vomiting), or these symptoms resolve within a few hours. These patients should re-ceive a complete blood count and may be discharged with in-structions to return if any symptoms recur.

Possible survivors are those who present with nausea and vom-iting that persists for 24 to 48 hours. They will experience a latent period, during which leukopenia, thrombocytopenia, and lym-phocytopenia occur. Barrier precautions and protective isolation are implemented if the patient’s lymphocyte count is less than 1200/mm³. Supportive treatment includes administration of blood products, prevention of infection, and provision of enhanced nutrition.

The improbable survival group is composed of those who have received more than 800 rad of total body penetrating irradiation. Acutely, people in this group demonstrate vomiting, diarrhea, and shock. Any neurologic symptoms suggest a lethal dose of ra-diation (Jarrett, 2001). These patients still require decontamina-tion, to prevent contamination of the area. Personal protection is essential, because it is virtually impossible to fully decontaminate these patients since all of their internal organs have been irradi-ated. The survival time is variable; however, death usually ensues swiftly due to shock. If there are no neurologic symptoms, the patient may be alert and oriented, similar to a patient with extensive burns. In a mass casualty situation, the nurse should expect to triage these patients into the black category, where they will receive comfort measures and emotional support. If it is not a mass casualty situation, aggressive fluid and electrolyte therapy are essential.

Although radiation, biological, and chemical events are not everyday events, when they do occur every facility and every nurse will need to know the basics of caring for affected patients.

Any terrorist-sponsored or unintentional radiation release can be sizeable and may require the entire hospital and prehospital staff to be prepared, recognize signs and symptoms of exposure, and rapidly treat victims without contamination of personnel, visitors, patients, or the facility itself.