M. SUBR CATEGORIES OF TERRORISTS INCIDENTS

There are five categories of terrorist incidents: biological, nuclear, incendiary, chemical, and explosive.

1. Biological agents pose serious threats considering their fairly accessible nature and the potential for their rapid spread. These agents can be disseminated in the following ways: aerosols, oral (contaminating food or water), dermal (direct skin contact), or injection. Inhalation or ingestion is the most likely.

The Centers for Disease Control list approximately 20 biological agents (bacterial agents, viral agents and biological toxins) which are considered as possibilities for terrorist use. Following is a list of those considered most likely to be used.

• Anthrax (Bacillus anthracis) infection is a disease acquired following contact with infected animals or contaminated animal products or following the intentional release of anthrax spores as a biological weapon. Exposure to an aerosol of anthrax spores could cause symptoms as soon as 2 days or as late as 6-8 weeks after exposure. Further, the early presentation of anthrax disease would resemble a fever or cough and would therefore be exceedingly difficult to diagnose without a high degree of suspicion. Once symptoms begin, death follows 1-3 days later for most people. If appropriate antibiotics are not started before development of symptoms, the mortality rate is estimated to be 90%.

• Bacillus anthracis toxin (produced by Clostridia botulinum) is the single most poisonous substance known, and poses a major bio-weapons threat because of its extreme potency and lethality; its ease of production, transport and misuse; and the potential need for prolonged intensive care in affected persons. Natural cases of botulism typically result from food contamination (food not or incompletely heated) with absorption of the toxin from the gut or a wound. The incubation period for food-borne botulism can be from 2 hours to 8 days after ingestion. Patients with botulism typically present with difficulty speaking, seeing and/or swallowing and may initially present with gastrointestinal distress, nausea, and vomiting preceding neurological symptoms.

• Plague (Yersinia pestis) is an infectious disease of animals and humans found in rodents and their fleas. Pneumonic plague occurs with infection of the lungs. The incubation period is 1 to 6 days and the first signs of illness are fever, headache, weakness, and cough productive of bloody or watery sputum. The pneumonia progresses over 2 to 4 days and may cause septic shock and, without early treatment, death. Person-to-person transmission of pneumonic plague occurs through respiratory droplets, which can only infect those who have face-to-face contact with the ill patient. Early treatment of pneumonic plague with antibiotics is essential.

• Smallpox (variola major) has an incubation period of 7 to 17 days following exposure. Initial symptoms include high fever, fatigue, and head and back aches. A characteristic rash, most prominent on the face, arms, and legs, follows in 2-3 days. Smallpox is spread from one person to another by infected saliva droplets that expose a susceptible person having face-to-face contact with the ill person.

• Tularemia (Francisella tularensis) is one of the most infectious pathogenic bacteria known, requiring inoculation or inhalation of as few as 10 organisms to cause disease. It is a zoonosis, with natural reservoirs in small mammals such as voles, mice, water rats, squirrels, rabbits and hares. Naturally acquired human infection occurs through a variety of mechanisms such as: bites of infected arthropods; handling infectious animal tissues or fluids; direct contact or ingestion of contaminated water, food, or soil; and inhalation of infective aerosols. Human to human transmission has not been documented. Aerosol dissemination by a terrorist would be expected to result in the abrupt onset of acute, non-specific febrile illness beginning 3 to 5 days later (incubation range, 1-14 days). Treatment is with antibiotics.

2. Nuclear incidents are expected to take one of two forms: threatened or actual detonation of a nuclear bomb or threatened or actual detonation of a conventional explosive incorporating nuclear materials. It is unlikely that a terrorist could acquire or build a functional nuclear weapon. Dispersal of nuclear materials with a conventional explosive would contaminate the bombsite and raise environmental decontamination and long-term health issues.

Nuclear indicators, short of actual detonation or obvious involvement of radiological materials, include observation for a Department of Transportation placard or decal, and radiation detection devices.

3. Incendiary incidents could be any mechanical, electrical, or chemical device used to cause a fire. Indicators of incendiary devices include multiple fires, remains of incendiary device components, odors of accelerants (e.g., gasoline), and unusually heavy burning or fire volume.

4. Chemical agents fall into five classes: nerve (disrupt nerve impulse transmission); blister (severe burns to eyes; skin; respiratory tract; blood (interfere with oxygen transport), choking; and irritating (designed to incapacitate).

• Nerve agents are similar to organophosphate pesticides, but with higher toxicity. Early symptoms include uncontrolled salivation, lacrimation (secretion of tears, especially in excess), urination, and defecation. These agents may resemble water or light oil and possess no odor, and are best dispersed as an aerosol. Many dead animals at the scene may indicate a nerve agent.

• Blister agents are also referred to as mustard agents due to their characteristic smell. They can be absorbed through the skin, and clinical symptoms may not appear for hours or days. These agents are heavy, oily liquids, dispersed by aerosol or vaporization.

• Blood agents interfere with oxygen transport by the blood, resulting in asphyxiation. Clinical symptoms include respiratory distress, vomiting and diarrhea, and vertigo and headaches. These agents are gasses, although precursor chemicals are typically cyanide salts and acids. All have the aroma of bitter almonds or peach blossoms.

• Choking agents stress the respiratory tract by causing edema (fluid in the lungs) which can result in asphyxiation. Clinical symptoms include severe eye irritation and respiratory distress. Most people recognize the odor of chlorine; phosgene has the odor of newly cut hay. Both are gases and must be stored and transported in cylinders.

• Irritating agents, also known as riot control agents or tear gas are designed to incapacitate. Generally, they are non-lethal; however, they can result in asphyxiation. Clinical symptoms include eye and throat irritation, respiratory distress, and nausea and vomiting.

5. Explosive agents, i.e., bombs, can be 1) readily made from commonly available materials (e.g., ammonium nitrate fertilizer and diesel fuel), 2) obtained from commercial sources (e.g., blasting agents and explosives), or 3) obtained from the military. These devices account for 70 percent of terrorist attacks.