Introduction

Historically, humankind has used poisonous chemicals to disable or kill insects, fish, or other animals for various purposes. Chemical warfare agents are poisonous chemicals that can rapidly cause death or disability to the enemy. The deployment of chemical weapons is the use of poisonous compounds in time of war with the intention to kill or incapacitate large numbers of the enemy. In World War I, tear gases, phosgene, chlorine, mustard gases, and other respiratory impairment agents were used. For example, German soldiers deployed chlorine gas on April 22, 1915, resulting in the deaths of more than 5,000 Allied troops. The overall casualty toll from chemical weapons during WWI is estimated at 100,000 deaths and 900,000 injuries.