Deliberate Disasters

In the last issue, part one reviewed the incidence of terrorist bombings and the types of injuries they produce. Part two discusses modifications of bombs designed to magnify their destructive effects.

Bombs With “Something Extra”

Because intense heat inactivates biological weapons, bioterrorism (BT) is not a bomb-associated threat; however, chemical and radiological weapons have been dispersed with terrorist bombs.

Chemical additives. Recycling German tactics from World War I, improvised explosive devices (IEDs) in Iraq have recently been reported to contain chlorine, which produces pulmonary damage synergistic with blast lung effects. Because of its high volatility, greater damage occurs within enclosed spaces than from an outdoor explosion. Other chemical weapons that could be utilized in bombs are phosgene, cyanide, sulfur mustard, and nerve agents such as sarin.

Radiological additives. Despite justified concern about nuclear weapons and components missing from the former Soviet Union, radiation dispersal devices (RDDs) or “dirty bombs” are more likely to contain low-level radioactive materials, such as waste products from medical radiation facilities. It is important to make the distinction here between “radiologic” and “nuclear” exposures. Nuclear explosions (caused by nuclear bombs or reactor accidents) involve fission and fusion reactions; they generate enormous blast/heat effects, hundreds of different radioisotopes, and large clouds of radioactive fallout. Consequently, the morbidity and mortality of nuclear events are dramatically greater and more widespread than from exposures to other forms of radioactivity.

Definitions:

• Radiation exposure: ionizing radiation has passed through the patient’s body, but the patient is not radioactive (e.g., this occurs when a patient has an X-ray).
• External contamination: the patient has radioactive material on his clothes, skin, and/or hair. Removing clothing usually provides 90 percent decontamination; a thorough shower will remove the rest of the external contamination.
• Internal contamination: radioactive material has entered the body via inhalation, ingestion, or radioactive shrapnel from an RDD. Whereas nonradioactive shrapnel can be left in the body if it is small and in noncritical areas, a meticulous effort must be made to remove all radioactive shrapnel.
• Incorporation: the uptake of radioactive material into cells. When an antidote exists, the goal is to administer it before incorporation takes place.
• Acute radiation syndrome (ARS): Usually caused by doses over 70 rads (0.7 Gray), ARS is divided into four stages:

• Prodrome: anorexia, vomiting, malaise;
• Latent stage: relatively asymptomatic period, which can last from hours to several weeks. The higher the dose, the shorter the latent stage;
• Manifest illness stage: marked by hematologic, gastrointestinal, cutaneous, and (with severe exposure) neurovascular abnormalities;
• Death or recovery.

Decontamination

The need for and urgency of patient decontamination depends on the type of exposure.

BT agents: Symptomatic patients have already gone through the incubation period; therefore, decontamination is unnecessary. However, an asymptomatic person with a credible history of having just been exposed to a bioagent such as anthrax needs to remove clothing, seal it in a plastic bag, and wash the skin/hair (evaluation for antibiotic prophylaxis is also indicated).

Radiologic agents: The purpose of an RDD is to maximize psychological terror and disrupt the usage of a now contaminated space; unless a nuclear reaction was involved, the radiation itself has far less impact on health than the bomb blast. While prompt decontamination of the patient is optimal, treatment of life-threatening blast injuries should never be delayed in order to perform decontamination. With proper personal protective equipment (PPE), healthcare workers (HCWs) have not been exposed to excessive doses of radiation when caring for contaminated patients. For example, HCWs who decontaminated workers exposed during the Chernobyl nuclear accident received maximum exposures equivalent to one pelvic CT scan.

Chemical agents: Depending on the agent, HCWs may be at risk of severe toxicity if patients are not decontaminated prior to entry to the facility. Many of these chemicals are rapidly and efficiently absorbed through the lungs, mucous membranes, and intact skin. During the Tokyo sarin incident, 10 percent of EMS personnel and 23 percent of hospital workers experienced secondary exposure, in part because the initial impression was carbon monoxide poisoning, so no consistent effort was made to remove the victims’ clothing or use PPE. The ICU staff suffered more adverse effects than the ED staff due to better ventilation in the ED and more severely poisoned patients in the ICU.

Should Clinics Attempt Decontamination?

Cyanide and nerve agents may cause seizures and sudden death; chlorine and phosgene may produce an ARDS-like picture; sulfur mustard produces painful bullae and bone marrow suppression — immediate decontamination in the clinic setting is a potentially life-saving measure that also reduces the risk of creating secondary HCW victims. A chemical agent that is a true gas usually requires less aggressive decontamination than a liquid or a vapor (particulate solids suspended in air). However, in a real-world setting, you are unlikely to know whether your patient was exposed to a gas or a vapor.

A decon kit is simple to assemble and use; the primary obstacle is low acceptability, which can be overcome by educating your staff in advance. A unified approach by the staff will in turn enhance patient cooperation. Ideally, chemical decontamination occurs outside the building; therefore privacy concerns must be taken into account.

Contents of a kit adequate to decontaminate 10 people:

• 1 large labeled container to hold everything listed below;
• 10 cloth surgical gowns;
• 10 white plastic bags;
• 10 extra large garbage bags, with holes cut out of the bottom large enough through which to place the head;
• 10 towels;
• 10 soap-impregnated sponges;
• Garden hose;
• Heavy duty butyl rubber gloves (at least four pairs).

How to use the clinic decon kit:

• Prior to the event, determine the location of an external water faucet and make sure that nothing prevents staff from attaching the hose and turning on the water. A diagram of the faucet location should be placed on the container lid.
• Contaminated persons are instructed to remove their clothing; the large garbage bags may be placed over the body for modesty. Clothing is placed in the white plastic bags (these bags should not be handled because chemicals may leach through plastic; however, they should be preserved as forensic evidence).
• Contaminated persons use the hose and sponges to wash themselves as thoroughly as possible (under the garbage bags, if used); towels are available for drying afterwards.
• Surgical gowns are worn until additional clothing is available.
• If staff is required to assist with washing or handling potentially contaminated objects, butyl rubber gloves should be worn (latex and nitrile will not protect against chemical exposure).

Mass Operations

The San Diego County Hazardous Incident Response Team (HIRT) can rapidly set up decontamination stations for large group exposures. For chemical agents, the process consists of walking (or being transported) through water from fire engine hoses; monitoring for hypothermia is a consideration here. For radiologic agents, the decon station is usually set up in a high school gymnasium. Potentially contaminated persons walk through portal radiation monitors, go to gender-specific locker rooms to shower, followed by a repeat pass through the monitor. Decontamination is considered adequate when residual radioactivity is less than two to three times the background radiation level. An inability to get to this level despite several showers suggests internal contamination and the need for further medical evaluation.

Dosimetry Reconstruction

Several physiologic parameters allow retrospective calculation of the approximate radiation dose, which then affords prediction of the patient’s clinical course and need for specific treatment modalities, such as reverse isolation, prophylactic antibiotics, transfusions, human granulocyte colony stimulating factors (G-CSF), and consideration for a bone marrow transplant. Mortality risk can also be estimated. Again, life-threatening radiation exposure is unusual from RDDs vs. nuclear bombs or reactor accidents. The three predictive criteria are:

• Speed and magnitude of the drop in peripheral lymphocytes in the first 24 hours;
• Interval between the radiation exposure and the onset of vomiting: the shorter the interval, the greater the exposure;
• Dicentric chromosome count (abnormal chromosomes with two centromeres, created after radiation-disrupted DNA reanneals).

A new Federal website provides nomograms and guidelines for patient management: www.remm.nlm.gov.

Radiation Antidotes

Certain radioisotopes have specific antidotes which speed decorporation (excretion). They are most effective when administered early:

• Iodine-125/131 → potassium iodide (KI)
  • Only useful for nuclear explosions
  • Only protects against thyroid cancer
  • Must be started within six hours of exposure
• Cesium-137 → Prussian blue
• Strontium-90 → Aluminum phosphate
• Americium-241, Plutonium-239, Cobalt-60 → Ca- and Zn-DTPA

The Strategic National Stockpile (SNS)

Administered by the Department of Homeland Security, the SNS contains drugs, supplies and equipment that are stored regionally for use during large-scale public health emergencies. Upon declaration of an emergency by a state governor, Federal “push-packs” can be delivered within 12 hours to the affected area(s) to be dispensed by local health officials. Examples of SNS contents are PPE, ventilators, ciprofloxacin, and oseltamivir. For radiation exposures, the SNS carries KI, Prussian blue, DTPA and G-CSF.

Conclusions

Unlike bioterrorism, which is usually a stealth attack initially recognized by alert clinicians or syndromic surveillance, bombings obviously attract the attention of law enforcement, and chemical warfare agents cause abrupt, dramatic symptomatology. However, mysterious clusters of illness could be caused by radioactive agents quietly dispersed in the community without the use of explosives; in this instance, it is also likely to be an alert physician who first concludes that there is an epidemic of ARS due to an intentional act. The San Diego County Community Epidemiology Branch (CEB) should be contacted immediately if you suspect that an incident of public health significance has occurred; during regular hours at (619) 515-6620; after hours and on weekends at (858) 565-5255.

How can a clinician best prepare for uncertainty? Besides updating policies and procedures and ensuring that your staff is trained, consider getting involved in hospital emergency planning: as of April 2007, the CDC reports that although 75 percent of hospitals have disaster plans that address the use of explosives, only one-fifth have conducted drills involving bomb scenarios. The Institute of Medicine’s 2006 report, Hospital-Based Emergency Care: At the Breaking Point, cites the following funding priorities: improved EMS response to explosives, standby ICU capacity, increased availability of decontamination showers, and chemical level PPE for HCWs. Terrorist bombings are becoming increasingly prevalent around the world. Although the United States has not been visited by this scourge recently, it is incumbent upon all of us to be ready for what the CDC has called “a predictable surprise.”