Nerve Agents

Nerve agents are not quickly and easily detected. Small quantities can quickly cause casualties and deaths. They may be colorless gases with little or no odor or colorless to light brown liquids. These agents radically disturb the chemical processes of the nervous system, which impairs or stops other bodily functions.

Nerve agents can enter the body by inhalation, ingestion, and absorption through the skin and eyes. Entry through the skin is extremely effective. This means that the protective mask alone is not adequate protection because the agent can enter through any exposed skin.

There are now two series or groups of nerve agents-the G series and the V series. The G series is composed of the following agents: tabun (GA), sarin (GB), and soman (GD); the V series is composed of agent VX.

The physical properties of the G agents are similar. The GA is a colorless to brownish liquid, which gives off a colorless vapor; GB and GD are both colorless to light brown liquids, which give off colorless vapors. All three G agents normally are nonpersistent, however, GA and GD are longer lived than GB. G agent poisoning displays approximately the same sequence of symptoms whether the agent enters the body by inhalation, absorption or ingestion. These symptoms, in usual order of appearance, are runny nose; tightness of chest; dimness of vision and pinpointing of the eye pupils; difficulty in breathing; drooling and excessive sweating; nausea; vomiting, cramps and involuntary defecation and urination; twitching, jerking and staggering; and headache, confusion, drowsiness, coma, and convulsion. All of these symptoms can take place in 30 seconds if the dose is sufficiently heavy. These symptoms are followed by cessation of breathing, then death. Symptoms appear much more slowly from skin dosage than from respiratory dosage. Although skin absorption great enough to cause death may occur in 1 to 2 minutes, death maybe delayed for 1 to 2 hours. Respiratory lethal dosages kill in 1 to 10 minutes, and liquid in the eyes kills almost as rapidly. The number and severity of symptoms that appear depend on the quantity and rate of entry of the nerve agent into the body.

Most of the detailed information about agent VX is classified and cannot be covered in this text. In general, V agents are colorless and odorless liquids that do not evaporate rapidly or freeze at very low temperatures. Because of their low volatility, their vapor effect is limited; thus, the duration of their effectiveness is increased. In liquid or aerosol form, V agents affect the body in a manner similar to that of the G agents. The V agents usually are disseminated as liquid droplets. When inhaled, these agents are inherently about five times as toxic as the older nerve agents (G series). When absorbed through the skin, the V series agents are several hundred times more toxic than the G agents, because there is no breakdown of the V agent (as there is in GB) as it passes through the fatty layer of the skin.

Blister Agents

The blister agents, used for casualty effect,

may restrict the use of ground personnel, slow troop movements, and hamper the use of material or installations. These agents affect the eyes and lungs and blister the skin, producing long-term incapacitation or death. Blister agents 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 to lewisite (L) and phosgene oxime (CX), which cause immediate pain on contact). The development of casualties is somewhat delayed; the effects of distilled mustard (HD) may appear in 4 to 6 hours after exposure. The first effect is eye irritation. Next, the more sensitive body parts are affected. A series of symptoms follow, ranging from slight redness to blistering and the forming of ulcers. Wet skin absorbs more mustard than dry skin. For this reason, lower concentrations of mustard HD are needed in hot, humid weather because the body is then moist with perspiration. This fact is important in the tropics. Protection from blister agents is extremely difficult, because they attack any part of the body that comes in contact with the liquid or vapor agent.

The primary blister agents, HD and HN, are most effective for general use. However, they are far less effective than the nerve agents for casualties that result in quick death from inhalation, because a high dosage of mustard vapor is required to produce death. Mustard is effective by absorption of both vapor and liquid through the skin. The physiological action is localized to the area of the skin that is contaminated, but it does not produce a systemic effect.

In the pure state, mustard is a yellowish, oily liquid. Because of its high boiling point, liquid mustard evaporates slowly at normal temperatures; consequently, it remains effective for a considerable length of time after application. In fact, in winter months, HD may produce casualties for several weeks after dissemination. On the other hand, the warm temperatures of summer, assisted by wind and rain, may reduce its capability to days. Almost every shipboard surface or material, except bright metal and glass, absorbs some mustard and retains it more or less persistently. Regardless of weather and wind, no shipboard surface contaminated with mustard should be considered completely free of this agent unless a negative test is obtained with a detector kit.

Because HD can be dissolved by fats, it may be dissolved in foodstuffs and make them poisonous. The action on metal is very slight.

Mustard can be dissolved easily in such commercial solvents as benzene and cleaning fluid, and in motor oils, but it is only slightly soluble in water. On prolonged standing, it reacts with water to produce harmless substances,

The newer blister agents include the nitrogen mustards (HN-1, HN-2, HN-3) and the mixed blister agent (HL). These mixtures do not produce more severe injuries than do other agents alone, but they have a lower freezing point than pure HD.