Nerve agents effects

Nerve agents inhibit ChE, which then cannot hydrolyze ACh. This classic explanation of nerve agent poisoning holds that the intoxicating effects are due to the excess endogenous ACh. This explanation, however, may not account for all nerve agent effects. 

In a casualty with mild-to-moderate intoxication from exposure to nerve agent vapor, administering the contents of MARK I kits can rapidly and completely reverse the nerve agent effects. Further triage decisions and medical care should focus on the conventional wound. 

If the casualty is not breathing because of nerve agent effects, attempting to provide ventilatory assistance might preclude the immediate care of a severe wound or other assistance in the contaminated area. If ventilation is marginal and the wound alone would classify the casualty as immediate, the time and effort required to stabilize ventilation might preclude timely wound care. The dual requirements might require more care providers than are available. 

One such decontaminant is supertropical bleach (STB). STB is a mixture of chlorinated lime and calcium oxide containing about 30% available chlorine. It can be used either as a dry mix or as a slurry to decontaminate some equipment surfaces and terrain. The dry mix is prepared with two parts bleach to three parts earth by volume. A slurry typically consists of 40 parts STB to 60 parts by weight of water. This material is then sprayed or swabbed on the contaminated surface (see Bleaching agents). STB is an effective decontaminant for mustard, lewisite, and VX. It is less effective against nerve agents other than VX. 

Field protection The principles applied to the nerve agents apply equally as well to the incapacitating agents. It is possible that such agents will be disseminated by smoke-producing munitions or aerosols, using the respiratory tract as a route of entry. The use of protective mask, therefore, is essential. The skin is usually a much less effective route. 

Both the G- and V-agents have the same physiological action on humans. They are potent inhibitors of the enzyme acetylcholinesterase (AChE), which is required for the function of many nerves and muscles in nearly every multicellular animal. Normally, AChE prevents the accumulation of acetylcholine after its release in the nervous system. Acetylcholine plays a vital role in stimulating voluntary muscles and nerve endings of the autonomic nervous system and many structures within the CNS. Thus, nerve agents that are cholinesterase inhibitors permit acetylcholine to accumulate at those sites, mimicking the effects of a massive release of acetylcholine. The major effects will be on skeletal muscles, parasympathetic end organs, and the CNS. 

Symptoms appear much more slowly from skin absorption. Skin absorption great enough to cause death may occur in 1-2 h. Respiratory lethal dosages kill in 1-10 min, and liquid in the eye kills nearly as rapidly. Very small skin dosages sometimes cause local sweating and tremors but little other effects. Nerve agents are cumulative poisons. Repeated exposure to low concentrations, if not too far apart, will produce symptoms. 

Typically, there is a latent period with no visible effects between the time of exposure and the sudden onset of symptoms. This latency can range from 1 minutes to 18 hours and is affected by such factors as the amount of agent involved, the amount of skin surface in contact with the agent, and the area of the body exposed (see Liquids). Moist, sweaty areas of the body are more susceptible to percutaneous penetration by solid nerve agents. 

Meat from animals that have suffered only mild to moderate effects from exposure to nerve agents should be safe to consume. Milk should be discarded for the first 7 days postexposure and then should be safe to consume. Meat, milk, and animal products, including hides, from animals severely affected or killed by nerve agents should be destroyed. 

Structural firefighters protective clothing is recommended for fire situations only it is not effective in spill situations or release events. If chemical protective clothing is not available and it is necessary to rescue casualties from a contaminated area, then structural firefighters gear will provide very limited skin protection against nerve agent vapors. Contact with liquids, solids, and solutions should be avoided. 

Reactive oximes and their salts, such as potassium 2,3-butanedione monoximate found in commercially available RSDL, are extremely effective at rapidly detoxifying nerve agents. Some chloroisocyanurates, similar to those found in the CASCAD, are effective at detoxifying V-series agents and so is oxone, a peroxymonosulfate triple salt. 

Solid hypochlorites (e.g., HTH, STB, and Dutch powder) should also be effective in destroying novichok series nerve agents. Reaction with hypochlorites, including household bleach, may produce toxic gases such as chlorine. 

Gordon, J.J., R.H. Inns, M.K. Johnson, L. Leadbeater, M.P. Maidment, D.G. Upshall, G.H. Cooper, and R.L. Rickard. The Delayed Neuropathic Effects of Nerve Agents and Some Other Organophosphorus Compounds." Archives of Toxicology 52 (1983) 71-82. 

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