The agents in this class are beta-halogenated thioethers, beta-halogenated alkylamines, and alkylating sulfates. The thioether agents are listed in Schedule 1 of the Chemical Weapons Convention (CWC). Only three beta-halogenated alkylamine agents, HN1 (C03A011), HN2 (C03-A012), and HN3 (C03-A013), are specifically listed in Schedule 1. However, because of the toxicity of the agents and limited commercial application, the remaining alkylamines would be prohibited based on the Guidelines for Schedules of Chemicals. Sulfur vesicants are first generation chemical warfare agents employed in World War I.

Mustard gas (dichloroethylsulfide) was discovered in 1822. It was first employed by the Germans in 1917 at the third battle of Ypres and has been considered amajor chemical agent ever since. Nitrogen vesicants are second generation chemical warfare agents developed just prior to World War II. In addition to their vesicant properties, nitrogen agents were studied as ameans of poisoning an enemies’water supply because dilute aqueous solutions will rapidly decompose and form neurotoxic products. Several of these agents, including HN3 (C03-A013), were stockpiled by Nazi Germany during World War II but were never used. Modernweapons researchers have isolated and evaluated numerous other variations of the basic thiol and amine structures. Both sulfur andnitrogenvesicants are easy to synthesize anddisperse. For informationon

some of the chemicals used to manufacture vesicants, see the Component Section (C03-C) following information on the individual agents. In addition to the agents detailed in this handbook, the Organisation for the Prohibition

of Chemical Weapons (OPCW) identifies in its Declaration Handbook 2002 for the Convention on the Prohibition of the Development, Production, Stockpiling, and Use of Chemical Weapons and on their Destruction another five agents in this class. However, there is no information available in the unclassified literature concerning the physical, chemical, or toxicological properties of these additional agents. Sulfur vesicants have been stockpiled by all countries that have pursued a chemical

weapons program and have been used numerous times on the battlefield. In contrast, although nitrogen vesicants have been investigated by the United States and many other countries, concern over agent stability and a lack of a clear strategic, tactical, or production advantage over sulfur vesicants has prevented further stockpiling of these agents.