*Nerve Agents*
By Swabbie

Physically, nerve agents are odorless, almost colorless liquids varying in viscosity and volatility. They are moderately soluble in water and fairly stable unless strong alkali or chlorinating compounds are added. They are very effective solvents readily penetrating cloth either as a liquid or vapor. Other materials, including leather and wood, are fairly well penetrated. Butyl rubber and synthetics, such as polyesters, are much more resistant.
Pharmacologically, the nerve agents are cholinesterase inhibitors. Their reaction with cholinsterases is irreversible; consequently, the effects of inhibition are prolonged until the body synthesizes new cholinesterases.

Signs and Symptoms of Exposure

Nerve agent intoxication can be readily identified by its characteristic signs and symptoms. If a vapor exposure has occurred, the pupils will constrict, usually to a pinpoint; if the exposure has been through the skin, characteristic local muscular twitching will occur.
Other symptoms will include rhinorrhea, dyspnea, diarrhea and vomiting, convulsions, hypersalivation, drowsiness, coma, and unconsciousness.


Specific therapy for nerve agent casualties is atropine, and acetylcholine blocker. For immediate self-aid, each individual is issued three automatic injectors containing 2mg of atropine sulfate for intramuscular injection or two autoinjectors containing the Nerve Agent Antidote. These injectors are designed to be used by individuals on themselves when symptoms appear. After the first injection, if the symptoms have not disappeared within 10 to 15 minutes, another injection should be given. If the symptoms still persist after an additional 15 minutes, a third injection may be given by non-medical personnel.
For medical personnel, the required therapy is to continue to administer atropine at 15-minute intervals until a mild atropinization occurs. This can be noted by tachycardia and a dry mouth. Atropine alone will not relieve any respiratory muscle failure. Prolonged artificial respiration may be necessary to sustain life.
Oxime therapy, using pralidoxime chloride, or 2-PAM Cl, may also be used for regeneration of the blocked cholinesterase. For individuals treated initially with the new autoinjector, additional oxime therapy is generally not medically indicated; it is already included in the autoinjector.


Blister agents or vessicants exert their primary action on the skin, producing large and painful blisters that are incapacitating. Although vessicants are classified as non-lethal, high doses can cause death.
Common blister agents include Mustard (HD), Nitrogen Mustard (HN), and Lewisite (L). Although each is chemically different and will cause significant specific symptoms, they are all sufficiently similar in their physical characteristics and toxicology to be considered as a group. Mustards are particularly insidious because they do not manifest their symptoms for several hours after exposure. They attack the eyes and respiratory tract as well as the skin. Further, there is no effective therapy for mustard once its effects become visible. Treatment is largely supportive, to relieve itching and pain and to prevent infection.

Mustard (HD) and Nitrogen Mustard (HN)

HD and HN are oily, colorless or pale yellow liquids, sparingly soluble in water. HN is less volatile and more persistent than HD and has the same blistering qualities.


The part of the body most vulnerable to mustard gas is the eyes. Contamination insufficient to cause injury elsewhere may produce eye inflammation. Vapor or liquid may burn any area of the skin, but the burns will be most severe in the warm, sweaty areas of the body; that is, the armpits, groin, and on the face and the neck. Blistering begins in about 12 hours but may be delayed for up to 48 hours. Inhalation of the gas is followed in a few hours by irritation of the throat, hoarseness, and a cough. Fever, moist rales (abnormal sounds in the lungs, usually heard with a stethoscope), and dyspnea (labored, difficult breathing) may develop. Bronchopneumonia is a frequent complication; the primary cause of death is massive edema or mechanical pulmonary obstruction.
Because the eye is the most sensitive part of the body, the first notable symptoms of mustard exposure will be pain and a gritty feeling in the eye, accompanied by spastic blinking of the eyes and photophobia.


There is no specific antidotal treatment for mustard poisoning. Physically removing as much of the mustard as possible, as soon as possible, is the only effective method for mitigating symptoms before they appear. All other treatment is symptomatic; that is, relief of pain and itching, and control of infection.

Lewisite (L)

Lewisite is an arsenical. This blistering compound is a light to dark brown liquid that vaporizes slowly.


The vapors of arsenicals are so irritating that conscious persons are immediately warned by discomfort to put on the mask. No severe respiratory injuries are likely to occur, except in the wounded who are incapable of donning a mask. The respiratory symptoms are similar to those produced by mustard gas. While the distilled mustard and nitrogen mustard cause no pain on the skin during absorption, Lewisite cause intense pain upon contact.


Immediately decontaminate the eyes by flushing with copious amounts of water to remove liquid agents and to prevent severe burns. Sodium sulfacetamide, 30% solution, may be used to combat eye infection after the first 24 hours. In severe cases, morphine may be given to relieve pain.
British Anti-Lewisite (BAL), dimercaprol, is available in a peanut oil suspension for injection in cases of systemic involvement. BAL is a specific anti-arsenical, which combines with the heavy metal to form a water-soluble, non-toxic complex that is excreted. However, BAL is somewhat toxic and an injection of more than 3mg/kg will cause severe symptoms.
Aside from the use of dimercaprol for systemic effects of arsenic, treatment is the same as for mustard lesions.

Blood Agents

Hydrocyanic acid (AC) and cyanogen chloride (CK) are cyanide-containing compounds commonly referred to as Blood Agents. These blood agents are chemicals that are in a gaseous state at normal temperatures and pressures. They are systemic poisons and casualty-producing agents that interfere with vital enzyme systems of the body. They can cause death in a very short time after exposure by interfering with oxygen transfer in the blood. Although very deadly, they are nonpersistent agents


These vary with the concentration and duration of exposure. Typically, either death or recovery takes place rapidly. After exposure to high concentrations of the gas, there is a forceful increase in the depth of the respiration for a few seconds, violent convulsions after 20 to 30 seconds, and respiratory failure and cessation of heart action within a few minutes.


There are two suggested antidotes in the treatment of cyanides. Amyl nitrate in crush capsules is provided as first aid. Follow-up therapy with intravenous sodium thiosulfate solution is required.
In an attack, if you notice sudden stimulation of breathing or an almond-like odor, hold your breath and don your mask immediately. In treating a victim, if no blood agents remain present in the atmosphere, crush 2 ampules of amyl nitrate in the hollow of your hand and hold it close to the victim’s nose. This may be repeated every few minutes until 8 ampules have been used. If the atmosphere is contaminated and the victim must remain masked, insert the crushed ampules into the mask under the faceplate.
Whether amyl nitrate is used or not, sodium thiosulfate therapy is required after the initial lifesaving measures. The required dose is 100 to 200 mg/kg given intravenously over a 10 minute period.
The key to successful cyanide therapy is speed; cyanide acts rapidly on an essential enzyme system. The antidotes act rapidly to reverse this action. If the specific antidote and artificial respiration is given soon enough, the chance of survival is greatly enhanced.

Choking or Lung Agents

The toxicity of lung agents is due to their effect on lung tissues. They cause extensive damage to alveolar tissue, resulting in severe pulmonary edema. This group includes phosgene (CG) and chlorine (CI) as well as  chloropicrin and diphosgene. However, CG is most likely to be encountered and its toxic action is representative of the group
Phosgene is a colorless gas with a distinctive odor similar to that of new-mown hay or freshly cut grass; unfortunately, the minimal concentration in the air that can cause damage to the eyes and throat is below the threshold of olfactory perception. Generally speaking, CG does not represent a hazard of long duration, so that if an individual were to be exposed to a casualty-producing amount, he/she should be able to smell it.


There may be watering of the eyes, coughing, and a feeling of tightness in the chest. More often, however, there will be no symptoms for 2 to 6 hours after exposure. Latent symptoms are rapid, shallow, and labored breathing; painful cough; cyanosis; frothy sputum; leadened, clammy skin; rapid, feeble pulse; and low blood pressure. Shock may develop, followed by death.


Once the symptoms appear, complete bed rest is mandatory. Keep victims with lung edema only moderately warm and treat the resulting anoxia with oxygen. Because no specific treatment for CG poisoning is known, treatment has to be symptomatic.

Psychochemical Agents

Psychochemical agents, often referred to as incapacitating agents, temporarily prevent an individual from carrying out assigned actions. These agents may be administered covertly by contaminating food or water, or they may be released as aerosols. The characteristics of the incapacitants:


The first symptoms appear in 30 minutes to several hours and may persist for several days. Abnormal, inappropriate behavior may be the only sign of intoxication. Those affected may make irrational statements and have delusions or hallucinations. In some instances, the victim may complain of dizziness, muscular incoordination, dry mouth, and difficulty in swallowing.
The standard incapacitant in the U.S. is 3-quinuclidinyl benzilate (BZ), a cholinergic blocking agent, which is effective in producing delirium that may last several days. In small doses it will cause an increase in heart rate, pupil size, and skin temperature, as well as drowsiness, dry skin, and a decrease in alertness. As the dose is increased to higher levels, there is a progressive deterioration of mental capability, ending in stupor.


The principal requirement for first aid is to prevent victims from injuring themselves and others during the toxic psychosis. Generally, there is no specific therapy for intoxication. However, with BZ and other agents in the class of compounds known as glycolates, physostigmine is the treatment of choice. It is not effective during the first four hours following exposure; after that, it is very effective as long as the treatment is continued. However, treatment does not shorten the duration of BZ intoxication, and premature discontinuation of therapy will result in relapse.

Riot Control Agents

“Riot Control Agents” is the collective term used to describe a divergent collection of chemical compounds, all having similar characteristics. They are relatively nontoxic compounds, which produce an immediate but temporary effect in very low concentrations. Generally, no therapy is required; removal from their environment is sufficient to effect recovery in a short time.
These agents are either lacrimators or vomiting agents


Lacrimators or tear gases are essentially local irritants that act primarily on the eyes. In high concentrations, they irritate the respiratory tract and the skin. These agents are used to harass enemy personnel or to discourage riot action. The principal agents used are chloracetophenone (CN) and orthochlorobenzilidine malinonitrile (CS). Although CS is basically a lacrimator, it is considerably more potent than CN and causes more severe respiratory symptoms. CN is the standard training agent and is the tear gas most commonly encountered. CS is more widely used by the military as a riot control agent. Protection against all tear agents is provided by protective masks and ordinary field clothing secured at the neck, wrists, and ankles. Personnel handling CS should wear rubber gloves for additional protection.


Lacrimators produce intense pain in the eyes with excessive tearing. The symptoms following the most severe exposure to vapors seldom last over 2 hours. After moderate exposure they last only a few minutes.


First aid for lacrimators generally is not necessary. Exposure to fresh air and letting the wind blow into wide open eyes, held open if necessary, is sufficient for recovery in a short time. Any chest discomfort after CS exposing can be relieved by talking.
An important point to remember is that this material adheres to clothing tenaciously, and a change of clothing may be necessary. Do not forget the hair, both head and facial, as a potential source of recontamination.

Vomiting Agents

The second class of agents in the riot control category are the vomiting agents. The principal agents of this group are diphenylaminochloroarsine (Adamsite {DM}), diphenychloroarsine (DA), and diphenylcyanoarsine (DC). They are used as training and riot control agents. They are dispersed as aerosols and produce their effects by inhalation or by direct action on the eyes. All of these agents have similar properties and pathology.


Vomiting agents produce a strong pepper-like irritation in the upper respiratory tract with irritation of the eyes and lacrimation. They cause violent uncontrollable sneezing, coughing, nausea, vomiting, and a general feeling of malaise. Inhalation causes a burning sensation in the nose and throat, hypersalivation, rhinorrhea (runny nose). The sinuses fill rapidly and cause a violent frontal headache.


It is of the utmost importance that the mask be worn in spite of coughing, sneezing, salivation, and nausea. If the mask is put on following exposure, symptoms will increase for several minutes in spite of adequate protection. As a consequence, victims may believe the mask is ineffective and remove it, further exposing themselves. While the mask must be worn, it may be lifted from the face briefly, if necessary, to permit vomiting or to drain saliva from the face piece. Carry on duties as vigorously as possible. This will help to lessen and shorten the symptoms. Combat duties usually can be performed in spite of the effects of vomiting agents if an individual is motivated.
First aid consists of washing the skin and rinsing the eyes and mouth with water. A mild analgesic may be given to relieve headache. Usually there is a spontaneous recovery, which is complete in 1 to 3 hours


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