Still too vague to be a useful working definition for field use. The Schedules do not define the chemicals in terms of specific properties, but classify according to general accepted usage. Where the chemical is placed in the schedules define whether or not it s use as a chemical weapon is legal or illegal according to the Ratified CW Convention. In essence, the chemical weapon of 1917 may well be today s common bug spray. Chemical Warfare Agents and Their Precursors.
Nerve agents are organophosphorous chemicals of very high toxicity.
The first nerve agent, tabun, was discovered in 1936 during a search for better pesticides. The mustard agents are comprised of 9 sulfur mustards and 3 nitrogen mustards. The lewisites have 3 different members. In the 1930s it was used against Abyssinia and China. In the 1980s against Iran.