Toxic Effects of Nerve Agents

Nerve agent poisoning is caused when the action of the enzyme acetyl cholinesterase is blocked. The normal function of acetyl cholinesterase is to break down (hydrolyze) the chemical acetylcholine. Acetylcholine is a neurotransmitter, or messenger chemical.

These sites include the endings of the parasympathetic nerves to the smooth muscle of the iris and eye, bronchial tree, gastrointestinal tract, bladder and blood vessels; to the salivary glands and secretor glands of the gastrointestinal tract and respiratory tract; and to the cardiac muscle and endings of sympathetic nerves to the sweat glands.

The sequence of symptoms varies with the route of exposure. While respiratory symptoms are generally the first to appear after inhalation of nerve agent vapor, gastrointestinal symptoms are usually the first after ingestion. Tightness in the chest is an early local symptom of respiratory exposure. This symptoms progressively increase as the nerve agent is absorbed into the systemic circulation, whatever the route of exposure. Following comparable degrees of exposure, respiratory manifestations are most severe after inhalation, and gastrointestinal symptoms may be most severe after ingestion.

WARNING! The lungs and the eyes absorb nerve agents rapidly. In high vapor concentrations, the nerve agent is carried from the lungs throughout the circulatory system; widespread systemic effects may appear in less than 1 minute.