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LESSON 2

LETHAL, INCAPACITATING AND MISCELLANEOUS CHEMICAL AGENTS

Critical Tasks:   031-506-2002

OVERVIEW

LESSON DESCRIPTION:

In this lesson you will learn a description of lethal, incapacitating, and miscellaneous chemical agents.

TERMINAL LEARNING OBJECTIVE:

INTRODUCTION

Nerve agents GB and VX and blister agents, HD, L, and CX are most likely to be used in chemical operations. While there are other nerve and blister agents, these are the most likely to be employed. Nerve agents act on the nervous systems or may interfere with breathing and cause convulsions, paralysis, and death. While different nerve agents differ in molecular structure, all nerve agents have the same physiological action. They cause an increase in acetylcholine throughout the body by interfering with the vital enzyme cholinesterase. In general, the peripheral nervous system of the body makes use of two chemicals to transmit information (impulses). These chemicals allow the nervous system to control voluntary (by choice) and involuntary, such as breathing, body functions. Nerve agents interfere with cholinesterase, which plays a vital role in the control of muscles around the skeleton. Nerve agents permit 'acetylcholine to persist at the muscle junctions with effects of a massive release of acetylcholine, causing an uncontrolled muscle function. The major effects will be on skeletal muscles, the heart, lungs, and central nervous system. See Table 2-4.

PART A - NERVE AND BLISTER AGENTS

1.   Nerve agents are highly toxic and among the deadliest of chemical agents. There are two types of nerve agents: the G-Series and V-Series. G-Series nerve agents include: Tabun (GA), Sarin (GB), and Soman, (GD). The V-Series nerve agents are VX and VY. Information on VY is limited, and therefore it will not be covered.

2.   Blister Agents. All of the blister agents are persistent, and all may be employed in the form of colorless gases and liquids. The blister agents are used primarily for casualty effects. They may also be used to restrict use of terrain, slow movements, and hamper use of material and installations. These agents affect the eyes and lungs and blister the skin. During World War I, mustard (HD) was the only blister agent in major use. It was recognized by a distinctive odor and had a fairly long duration of effectiveness under normal weather conditions. Since then, blister agents have been developed which are odorless and vary in duration of effectiveness. Most blister agents are insidious in action there is little or no pain at the time of exposure except with Lewisite(L) and phosgene oxime(CX), which cause immediate pain on contact. The development of casualties is somewhat delayed. CX produces a wheal (similar to a bee sting) rather than a water blister, which the other blister agents produce. Protection from blister agents is extremely difficult.

3.   Persistent agents are employed over terrain that friendly forces do not plan to use or against rear targets for disruption or interdiction.

Nonpersistent agents are employed against unprotected enemy troops occupying terrain that friendly forces plan to cross or occupy. A nonpersistent agent should be used to avoid creating a residual hazard. A nonpersistent agent is used as a vapor or aerosol to cause casualties. A nonpersistent agent is used to force troops to assume and maintain a protective posture and to degrade combat efficiency. Unprotected troops, those not wearing masks at the time of the attack, are immediate casualties. All nonpersistent agents produce immediate casualties.

Table 2-1 provides a list of persistent and nonpersistent chemical agents.

Table 2-1.   Chemical Agents

PART B - BLOOD AND CHOKING AGENTS

1.   Blood and choking agents primarily enter the body through the respiratory system. These agent are nonpersistent agents. They are normally effective only against personnel not wearing protective masks and clothing. The standard protective mask gives adequate protection against field concentrations of blood agents. Impermeable protective clothing and the mask is needed when liquid AC is handled. Blood agents produce their effects by interfering with normal utilization of oxygen within the body. Inhalation is the usual route of entry. Hydrogen cyanide (AC) and cyanogen chloride (CK) are the important agents in this group. Cyanogen chloride also acts as a choking agent. These agents can be dispersed by artillery or mortar shells, rockets, aircraft spray, and bombs.

CK is a quick-acting casualty agent. It also causes degradation of canisters of filter elements in protective masks. This makes an individual more vulnerable to a subsequent lethal agent attack. CK acts in two ways. Its systemic effects are similar to those of AC, but it also has local irritant effects on the eyes, upper respiratory tract and lungs. CK damages the respiratory tract resulting in severe inflammatory changes in the bronchioles, and congestion and edema in the lungs. The fluid in the lungs may accumulate much faster than in phosgene poisoning. All concentrations of CK produce eye irritation and lacrimation. CK can be detected by the same methods as those for AC. In addition, decontamination is not required under field conditions.

2.   Choking Agents. Chemical agents which attack lung tissue, primarily causing pulmonary edema, are classified as choking agents. Best known of these agents is phosgene. Agents in this class are called choking agents because irritation of the bronchi, trachea, larynx, pharynx, and nose may occur and, with pulmonary edema contribute to the sensation of choking. Blister agents and certain systemic agents also may injure the respiratory tract. Since the action of phosgene is typical of the choking agents, it is used as the example in this part of the lesson. Persons exposed to phosgene need not be withdrawn during combat unless signs of pulmonary distress appear. The medical officer should advise the responsible commanding officer.

CG is used as a delayed-action casualty-producing agent although immediate symptoms may follow exposure to high concentrations of CG. A standard field protective mask or a gas-particulate filter unit (collective protector) gives adequate protection against choking agents. Detection of phosgene prior to contamination can be accomplished by using the M8 or M18A2 Automatic Chemical Agent Alarm System and odor. Decontamination is not required under field conditions.

3.   Both blood and choking agents are nonpersistent agents. This allows friendly troops to occupy an area after the agents have been used. Since they are used as vapors or aerosols, they tend to evaporate quickly, leaving little residual hazard.

Table 2-2 provides a list of blood and choking agents which are nonpersistent.

Table 2-2.   Nonpersistent Agents

PART C - MISCELLANEOUS AND INCAPACITATING AGENTS

1.   Incapacitating chemical munitions are employed on selected targets to incapacitate enemy forces when the use of lethal or destructive munitions is undesirable. They are normally used to accomplish the following. See Table 2-1.

• Incapacitating chemical attacks are made against hard targets, such as fortifications, to obtain delayed and relatively long-term neutralization of personnel. This will permit delayed exploitation or capture by friendly forces when the stage of battle permits, if the initial attack is made at long range. Such an attack can assist in the rescue of friendly personnel imprisoned in the fortifications.
• Incapacitating chemical attacks can be made to reduce overall fighting capability of intermingled enemy and friendly military units when the location of these units is not well known. This will permit the identification, delayed selective followup, and physical separation of friendly military units intermingled with enemy units without incurring heavy casualties among friendly troops.
• Incapacitating chemical attacks can be made to reduce the overall capability of intermingled enemy, captured friendly, and civilian personnel in an area. This will permit delayed selective followup and physical separation of personnel by friendly forces without incurring heavy civilian (or captured) friendly casualties.
• Incapacitating chemical attacks can be made against selected targets to assist in the capture of vital or sensitive enemy installations for intelligence purposes or to interfere with enemy use of such installations.

2.   An incapacitating agent is an agent producing physiological or mental effects that may persist for hours or days after exposure to the agent has ceased In actual usage, however, the term refers to those agents which:

• Produce their effects mainly by altering or disrupting the higher regulatory activity of the central nervous system.
• Have effects which last a significant period of time, rather than momentary or fleeting action.
• Do not seriously endanger life except at quantities greatly exceeding the effective dose, and produce no permanent injury.
• An individual will recover without treatment and without any permanent effects.
• Are highly potent and logistically feasible.

3.   Incapacitating agents DO NOT include the following:

• Lethal agents which are incapacitating as sublethal doses, such as the nerve agents.
• Substances which cause permanent or long-lasting injury, such as blister agents, choking agents, and those causing eye injury.
• Medical drugs which exert marked effects on the central nervous system, such as belladonna alkaloids, barbiturates, tranquilizers, and many of the hallucinogens. These drugs, although effective and relatively safe, are logistically infeasible for large-scale use because of the high doses required.
• Agents of temporary effectiveness which produce reflex responses interfering with performance of duty. These include skin and eye irritants causing pain or itching (vesicants or urticants), vomiting or cough-producing compounds (sternutators), and tear compounds (lacrimators).
• Agents which disrupt basic life-sustaining systems of the body and thus prevent the carrying out of physical activity. Examples include agents which lower blood pressure, paralyzing agents such as curare, fever-producing agents, respiratory depressants, and blood poisons. Although theoretically effective, such agents almost invariably have a low margin of safety between the effective doses and the possibly lethal doses and thus affect the basic purpose of an incapacitating agent, which is to reduce military effectiveness without endangering life.

4.   General Types. In spite of the restrictions imposed by the above definition, a great variety of mechanisms remain by which central nervous system regulation and maintenance of performance could theoretically be disrupted. In reality, however, only two general types of incapacitating chemical agents are likely to be encountered in military use. These are central nervous system depressants and central nervous system stimulants.

Cannabinols (marihuana) and phenothiazine type compounds are other potential incapacitating agents which seem to act basically as central nervous system depressants. Euphoria, a relaxed, unconcerned daydreaming attitude, easy laughter, hypotension and dizziness when standing up suddenly are signs and symptoms of marihuana use. The primary effects of these agents, however, are to sedate and destroy motivation rather than disrupt the ability to think.

The officer/NCO in charge should be prepared to take the following steps after the occurrence of a suspected chemical attack with incapacitating agents.

5.   Decontamination. The skin should be completely cleansed with soap and water at the earliest opportunity. The M258A1 Kit can be used if washing is impossible. Symptoms may appear as late as 36 hours after contact exposure, even if the skin is washed within an hour. In fact a delay in onset of several hours is typical. This time should be used to prepare for the possibility of a widespread outbreak 6-24 hours after the attack. Caustic alcohol solutions can be used to decontaminate bulk quantities of BZ.

Table 2-3.   Incapacitating Agent Signs and Symptoms

Table 2-4.   Chemical Agents

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