In general, chemical weapon agents are organized into several categories (according to the physiological manner in which they affect the human body).
They are often referred to as Riot Control Agents (RCAs) and may be used by civilian police forces against criminals and rioters, or in the military for training purposes.
In general, harassing agents are sensory irritants that have fleeting concentration dependent effects that resolve within minutes after removal.
These are substances that produce debilitating effects with limited probability of permanent injury or loss of life.
The casualty effects typically last over 24 hours, and though medical evacuation and isolation is recommended, it is not required for complete recovery.
These substances are sometime referred to as pulmonary agent or lung irritants and cause injury to the lung-blood barrier resulting in Asphyxia.
One mechanism of disruption, utilized by the G, GV, and V series of chemicals is caused by blocking the acetylcholinesterase, an enzyme that normally destroys and stops the activity of acetylcholine, a neurotransmitter.
A separate class of nerve agents are related to Tetrodotoxin, frequently abbreviated as TTX, is a potent neurotoxin with no known antidote.