The sum of all fears: Know history, consequences of nuclear terrorism

Awesome destruction, the shroud of radiation

Though nuclear weapons are one of the few potential bioterrorism agents that have actually been used against human populations, in many ways, the Cold War’s ultimate weapon remains as poorly understood as some emerging, exotic pathogen.

Nuclear terror would cause massive panic and social disruption — among the public and even health care workers — because radiation essentially would function like an unknown agent, according to new hospital response guidelines by the Centers for Disease Control and Prevention (CDC).1 The most likely psychological consequence is fear, "primarily because many people know a little about the effects of radiation and assume that radiation is more dangerous than it actually might be," the CDC emphasized. But before we move on to radiation, it is sobering to underscore the sheer destructive power of the worst-case scenario: a nuclear explosion. A recent study estimated that a bomb with the explosive power of 10,000 tons of TNT (smaller than that dropped on Hiroshima) — if set off in midtown Manhattan on a typical workday — could kill half a million people and cause over $1 trillion in direct economic damage.

"It is worth remembering just how awesome the power of nuclear weapons is: 10,000 metric tons of TNT is over 20 million pounds of high explosive — enough to fill a cargo train 100 cars long," the paper concluded.1

Beyond the actual physical destruction of a bomb blast, much of the terror in this weapon centers on the unknowns of radiation. What is nuclear radiation, and how does it cause harm to health?

Radiation 101

"Radiation is essentially energy that is transported in the form of particles or waves," said James Smith, PhD, assistant director for radiation in the CDC’s division of environmental hazards and health effects. "Also, keep in mind that the type of radiation we are talking about here is nuclear or ionizing radiation. We are not talking about microwaves, radiation from cell phone towers, or things like that."

The principle author of new CDC hospital guidelines for responding to a nuclear incident, Smith outlined the terrorism threat recently during a CDC satellite training broadcast for clinicians and public health officers. In a nutshell, radioactive materials contain disintegrating atoms.

The number of atoms disintegrating per second measures the "radioactivity" of something.

Disintegrating atoms emit different forms of radiation — alpha particles, beta particles, gamma rays, or X-rays. As radiation waves move through the body, they in turn dislodge electrons from atoms, disrupting molecules and possibly causing short- or long-term damage.

"When we are looking at exposure to radiation, what we are speaking of is irradiation of the body," Smith said. "The body has been exposed to a source of radiation. The energy from that radiation can be absorbed by the body. This leads to an absorbed dose, which is measured in units of grays’ or rads.’ With very high absorbed doses, one can get severe effects."

The most severe effect of radiation exposure is acute radiation syndrome (ARS). ARS is a serious illness that usually occurs when the body receives a high dose of radiation over a short period of time. Many survivors of the Hiroshima and Nagasaki atomic bombs in 1945 and many of the firefighters who first responded after the Chernobyl Nuclear Power Plant accident in 1986 became ill with ARS, the CDC reported.

The first symptoms typically are nausea, vomiting, and diarrhea. These symptoms may come and go, lasting for minutes or several days. Then the victim usually looks and feels healthy for a short time, but typically relapses and suffers loss of appetite, fatigue, fever, nausea, vomiting, diarrhea, and possibly seizures and coma. This seriously ill stage may last from a few hours up to several months, the CDC stated.

"The chance of survival for people with ARS decreases with increasing radiation dose," the guidelines explained. "Most people who do not recover from ARS will die within several months of exposure. The cause of death in most cases is the destruction of the person’s bone marrow, which results in infections and internal bleeding."

While radiation is much feared and little understood, the risk of an attack is more clearly defined than with most bioterror agents. There is real concern that terrorist groups may gain access to existing nuclear weapons, acquire the raw materials necessary to build a crude device, or unleash radiation upon the public through a variety of possible attack modes. Indeed, some consider nuclear terror as a more plausible and immediate threat than the use of biological or chemical agents.

"It is possible that radiation could be used as an agent of harm to terrorize communities," Smith said. "There could be a direct attack or some kind of sabotage on a nuclear power plant [for example]. That could result in a release of radioactive material [and] produce significant radiation exposure."

The much-publicized threat of a dirty bomb — the use of a conventional explosive to disperse radioactive material — is but one of several possible attack scenarios. "A dirty bomb is a conventional type of explosive device that is laced with or contains a radioactive substance," Smith said.

"When the bomb goes off, it spreads the radioactive substance over a large area — perhaps several city blocks, depending on the size of the blast. This would not only kill and injure people, but it would irradiate victims. It would also expose people like the first responders and continue to expose people in the aftermath of the explosion," he noted.

While it effectively would terrorize people and pose long-term health effects for exposed survivors, the radiation levels created by a dirty bomb would not likely be sufficient to cause ARS in those exposed. However, an attack on a nuclear power plant, (i.e., a plane crash into the structure) could result in sufficiently severe exposures of those in the immediate vicinity. More insidiously, a source of radioactive material could be hidden in a public place, causing a range of potentially severe exposures for as long as it remained undetected, Smith noted.

"A hidden source of radiation — that is a source of radiation stolen from an industrial or medical facility — could be hidden in a public place, like a city park, and expose people without their knowledge," he said. "It could even give potentially lethal doses of radiation to people."

Of course, the aforementioned worse-case scenario would be the actual denotation of a nuclear device. The physical devastation would not only dwarf the scenes of 9/11, but also create airborne clouds of highly radioactive dust and debris.

"There will be thousands of people in a large area potentially extending many miles outward from the initial point of attack with serious radiation exposures, although they may have no obvious physical injury or contamination," the CDC guidelines stated.

"Radioactive fallout with potential for long-term health effects will extend over a large region far from ground zero. There would likely be many persons experiencing symptoms related to acute radiation syndrome."

Such an event is "highly unlikely," Smith said, but he added that "the consequences would be so devastating that it is simply prudent of us in the medical community and public health to take them into consideration as we plan." Whether via an improvised device or an obtained bomb, "if successfully detonated, it would be an actual nuclear blast similar to Hiroshima and Nagasaki," he added.

A small nuclear device designed to fit inside a suitcase could have the power of about one-tenth of the blast of the Hiroshima bomb, he said.

The challenge of mass triage

If a nuclear terrorism attack occurs, the CDC projects that large numbers of patients — including both the injured and those concerned about potential exposure — would seek medical care. Thus hospitals and public health agencies must prepare for the unique features of radiological terrorism, such as mass casualties with blast injuries combined with burns, radioactive contamination, and acute radiation syndrome, the CDC advises.

Triage will be conducted at the scene and at the hospital, but communities and responders should attempt to do as much as possible at the scene or in a designated area outside the emergency department.

"If you bag the patients clothing and personnel belongings at the scene, that would typically remove about 80% to 90% of the contamination," said Fun Fong, MD, a speaker on the CDC training program and former director of radiation medicine at the medical sciences division of Oak Ridge (TN) Associated Universities. "The remaining contamination would usually be on the head and feet."

Under the triage process outlined by the CDC, patients with life-threatening conditions would be directed to emergency department staff to be stabilized and treated for physical symptoms according to standard procedures. Patient wounds are a decontamination priority because they pose a potential entry point for internal radiation contamination.

"You decontaminate much the way you decontaminate any trauma wound," Fong said. "But you want to do [radiological instrument] surveys in between debridement and irrigation attempts. It is not necessary to remove the last little bit of radiation. [You want] to debride but not to mutilate tissues. You want to gently decontaminate and rinse these wounds. Also, changing dressing frequently will remove [more] contamination."

The patient should be washed with water and soap, taking care not to abrade or irritate the skin. Ambulatory patients can be washed easily; however, nonambulatory patients must be on gurneys that can be washed, the CDC advises.

Staff trained in using survey instruments should resurvey the patient after washing. "A good rule of thumb is that one can stop when the decontaminated area is less than twice the level of background radiation," Fong said.

The threat of contamination to the worker from the patient generally is considered minimal if proper precautions are taken, and thus it should not delay patient treatment for serious medical conditions, he strongly emphasized. "Never, never delay critical care just because the patient is contaminated," Fong said. "That is the source of extra morbidity and mortality. Indeed, according to the Radiation Emergency Assistance Center/ Training Site (REAC/TS) in Oak Ridge, TN, no health care worker in the United States responding to a contamination accident has ever received a medically significant exposure to radiation.

Still, while patient care is a top hospital priority, it is vital that hospital personnel are protected. During a mass-casualty radiological event, it is likely that hospital personnel will be concerned about radiation contamination. To alleviate their concern, they should be educated about the potential health effects resulting from radiation exposure, learn what personal protective equipment they will need for precautionary measures, and be trained so they can respond effectively, the CDC stated. Plans should include a decontamination and cleaning area for workers. In addition, hospitals must prepare for potential psychological effects resulting from such a stressful event.

Staff should use standard precautions when making direct contact with contaminated patients. "Use the same gear you would be using for trauma response," Fong said. "That is body fluid isolation, barrier protection and, if particulates are a concern, use an N95 mask." Some data suggest that if N95 respirators are not available, surgical masks should provide adequate protection if other precautions are observed, the CDC added. The CDC recommends wearing double gloves, with the inner one taped and the outer glove removed after each patient contact.

"There should be no delay in the response," Fong said. The radiation dose rate of most contamination is very low, but while it remains on the patient, it will continue to expose the patient and the staff and it is a theoretical hazard for transferable contamination and poses a hazard to both responders and patients."

The other main stream of the triage process is for patients with nonlife-threatening conditions: For those patients, if contamination is detected (by radiological monitoring devices) or suspected, remove the patient’s clothing, give the patient a shower, then treat physical symptoms according to standard procedures, the CDC recommended. Localized contamination can be rinsed off with premoistened wipes or washed with soap and water as opposed to showering the individual. If radiation still is detected after washing, admit the patient if medically warranted and arrange for further evaluation and decontamination.

When possible, trained staff should survey all patients for radioactive contamination using devices such as radiation survey equipment to measure beta and gamma rays. Radiation survey equipment to detect contamination includes a Geiger counter to detect beta and gamma radiation. Although not specifically designed to quantify alpha radiation, pancake probes that are available for Geiger counters will detect the presence of most alpha radiation sources, as well as beta and gamma radiation, the CDC guidelines suggested.

But if staff are being overwhelmed by a large volume of incoming patients, a two-stage screening process can be used to separate out patients with high readings and designate them to another area for more evaluation. Fong suggested the use of Geiger counters to quickly detect those highly contaminated and send them for more thorough radiological surveys.

"Ideally, it would be nice to survey absolutely everybody," Fong said. {But] we have to [periodically] in medicine take a quick look around the room and see if anyone’s dying on us. In similar fashion, we can also look quickly with the survey meter. Are we dealing with a significant radiation level, or is it a lower radiation level that we might not be as concerned about? On those, we can wait a little bit to do a more thorough exam, so radiation surveys can be done in two stages."

References

1. Smith JM, Spano, MA. Interim Guidelines for Hospital Response to Mass Casualties from a Radiological Incident. Atlanta: Centers for Disease Control and Prevention; 2003. Web site: www.bt.cdc.gov/radiation/pdf/MassCasualtiesGuidelines.pdf.

2. Bunn M. Preventing Nuclear Terrorism: A Progress Update. Cambridge, MA: Project on Managing the Atom, Harvard University, and the Nuclear Threat Initiative; 2003.