Chemical irritants or riot control agents (RCAs) as they are known under international law, such as tear gas or pepper spray, are used around the world by a range of actors for both personal protection and ‘crowd management’.
The most common chemicals used in law enforcement include o-Chlorobenzylidene Malononitrile (CS), Chloroacetophenone (CN), and Dibenz(b,f)-1,4-oxazepine (CR), which are often referred to as ‘tear gases’, and oleoresin capsicum (OC) and pelargonic acid vanillylamide (PAVA) which are often referred to as ‘pepper sprays’. OC is naturally derived from the capsicum species of plant (such as chilli peppers) whereas PAVA is a synthetic formulation of one of the active ingredients in OC. Other less commonly used irritants or ‘tear gases’ include N-nonanoylmorpholine (MPK/MPA) which is manufactured predominantly in the Russian Federation and Ukraine, and Diphenylaminearsine (DM, or Adamsite).