CHAPTER 6 - Organophosphate Nerve Agents

Abstract

The chemical warfare (CW) nerve agents primarily addressed in this chapter include the anticholinesterase nerve agents tabun (GA), sarin (GB), soman (GD), cyclosarin (GF), and VX, all of which are, or have been, part of the US domestic munitions inventories. These agents are potent anticholinesterase compounds deliberately formulated to induce debilitating effects or death during wartime hostilities, and have been used by military authorities of several nations to develop munitions. All of the nerve agents under consideration are anticholinesterase compounds and induce accumulation of the neurotransmitter acetylcholine (ACh) at neural synapses and neuromuscular junctions by phosphorylating acetylcholinesterase (AChE). Depending on the route of exposure and amount absorbed, the PNS and/or CNS can be affected and muscarinic and/or nicotinic receptors may be stimulated. Interaction with other esterases may also occur, and direct effects to the nervous system have been observed. Exposure to acutely toxic concentrations of nerve agents can result in excessive bronchial, salivary, ocular, and intestinal secretions, sweating, miosis, bronchospasm, intestinal hypermotility, bradycardia, muscle fasciculations, twitching, weakness, paralysis, loss of consciousness, convulsions, depression of the central respiratory drive, and death. More recent global events have focused attention on the potential threat of chemical terrorism, especially at transportation hubs. For example, the deliberate release of nerve agent sarin at lethal concentrations in the Japanese cities of Matsumoto (1994) and Tokyo (1995) by a Japanese domestic terrorist group has illustrated that such attacks can be a reality and require advance emergency preparedness planning.