Nerve chemical-warfare agents

[Gregory]

There are many types of chemical-warfare agents that affect different parts of the body. Nerve agents (sometimes incorrectly called

[Marquetta]

Nerve agents are chemical-warfare agents that act directly at nerve synapses, typically increasing the activity of acetylcholine.
Other chemical agents were used in combat before World War II and are sometimes called first-generation chemical agents. Second- and 3rd-generation chemical agents include 2 types of nerve agents:

G-series agents (2nd-generation)
V-series agents (3rd-generation)

G-series agents, or G agents, include GA (tabun), GB (sarin), GD (soman), and GF (cyclosarin), which were developed by Nazi Germany before and during World War II. V-series agents include VX; these compounds were synthesized after World War II.
All nerve agents are organophosphorus esters, as are organophosphate pesticides. However, nerve agents are far more potent; the LD50 (the amount required to cause death in half of people receiving that dose) of VX is approximately 3 mg.
At room temperature, G agents are watery liquids with high volatilities and pose both skin-contact and inhalational hazards. VX is a liquid with the consistency of motor oil and that evaporates relatively slowly. None of these agents has a pronounced odor or causes local skin irritation.
Fourth-generation agents are nerve agents created after the development of VX. Much information about them remains classified. They include the A-series agents, or Novichok compounds, which are low-volatility nerve agents even more persistent than VX. One of the A agents was used in a 2018 assassination attempt in the United Kingdom.