Nerve agents are the most toxic agents in existence which when used as a
chemical weapon can lead to considerable destruction to human health and possibly countless loss of life. Nerve agents such as soman, sarin and organophosphates (pesticides) are among the most lethal chemical agents that are used as weapons because of its toxic effects to the human body.
Nerve agents are effective in small quantities, inexpensive, easily dispersed and highly effective in causing damage to the human body. In liquid form, nerve agents are highly volatile when exposed to air and once it evaporate, it becomes a colorless and odorless vapor. Organophosphates are very similar to nerve agents and for this reason, it is similarly used as a chemical weapon because of its toxic effects on the human body considering it is easily and readily available in most agricultural industries.
Common nerve agents as chemical weapons
Nerve agents can be inhaled or absorbed percutaneously or subcutaneously. These agents readily bond with acetylcholinesterase which results in inhibiting the body’s abundant neurotransmitter, acetylcholine, by adversely over-stimulating the nerve endings resulting in hyper-stimulation and dysfunctional rigidity of the peripheral nervous system. Carbamates, which are a common ingredient in pesticides and insecticides specifically act as a potent nerve agent that inhibit acetylcholinesterase for several hours and then spontaneously become an unbound form of acetylcholinesterase. Whereas organophosphates require the formation of a new enzyme before the nervous system function can be restored and revert back to its functional level.
A very small drop of a nerve agent is more than enough to result in profuse sweating and twitching at the site of exposure. A much larger amount and longer time of exposure result in more systemic symptoms. Effects can begin as early as 30 minutes tom as long as 18 hours following exposure. The more common organophosphates and carbamates (malathion, sevin) which are commonly used by the agricultural industry result in less severe symptoms than those used in chemical warfare or in terrorist attacks. In ordinary circumstances (non-warfare, non-terrorist attack), a victim from an organophosphate exposure normally would be a result of unintentional, careless use of the agent or intentionally used in suicide attempts.
Clinical manifestations of nerve agents
Signs and symptoms of nerve agents and nerve gas exposure are those of cholinergic crisis and include bilateral miosis, visual disturbances, increased gastrointestinal motility, nausea and vomiting, diarrhea, substernal spasm, indigestion, bradychardia and atrioventricular block, bronchoconstriction, laryngeal spasm, weakness, fasciculation and incontinence. Neurologic responses include insomnia, forgetfulness, impaired judgment, depression and irritability. Moreover, a lethal dose result in loss of consciousness, seizures, copious secretions, fasciculation, flaccid muscles and apnea.
Treatment for nerve agents
Decontamination with copious amounts of soap and water or saline solution for 8-20 minutes is very important for percutaneous contamination. Fresh 0.5% hypochlorite solution (bleach) can also be used. Atropine 2-4 mg is administered IV, followed by 2 mg every 3-8 minutes for up to 24 hours of treatment is. Alternatively, IV atropine 1-2 mg/hr may be administered until clear signs of anticholinergic activity have returned (decreased secretions, tachycardia, and decreased gastrointestinal motility). Another medication that may serve as an antidote is Pralidoxime, which allows cholinesterase to become an active agent against acetylcholine. Pralidoxime 1-2 grams in 100-150 ml of normal saline solution is administered 15-30 minutes. This emergency treatment for nerve agents may have the following side effects such as hypertension, tachycardia, weakness, dizziness, blurred vision and diplopia.