Themajority of thesematerials are organic sulfur compounds thatmay also contain an odor intensiﬁer. These chemicals are generally volatile liquids at room temperature with odors that are detectable at very low levels. Under normal battleﬁeld conditions, these materials do not pose a serious danger to the life of an exposed individual and do not produce any permanent injury. Since approximately 0.2% of the population is unable to detect odors (anosmic), compositions may contain multiple malodorant components. Obnoxious smelling agents have been used throughout history to provide camouﬂage
and assist in breaching hardened defensive positions. Ancient Chinese armories included various “stink bombs.” Research into development of new andmore effective malodorants began after World War I. During World War II, an agent known as “Who Me?,” which smelled of rotting food and carcasses, was developed by the Allies and tested by resistance ﬁghters on German and Japanese soldiers in an effort to humiliate and embarrass them. However, the agent was volatile and difﬁcult to deliver and did not always produce the expected response. As a result of this failure, malodorants were largely abandoned in the United States until the 1980s. Currently, malodorants are high on the list of nonlethal research priorities for use in riot control, to clear facilities, to deny an area, or as a taggant. Stench weapons in development include concentrates of natural odors such as those produced by skunks, rotting meat, excrement, and body odor. Since odors can provoke varying reactions in people based on their social and cultural conditioning, malodorants offer the possibility of ethnic or cultural targeting. Natural malodorants derived from a biological entity are prohibited under the Biological
Weapons Convention. Malodorants composed strictly of synthetic chemicals would be deﬁned as riot control agents and the Chemical Weapons Convention bans the use of such agents during a war. However, they may still be used by the military during operations other than war such as when responding to incidents of civil unrest. The military has also used many of these materials as simulants for lethal chemical agents. Malodorants have also been developed for use by police to control rioters and disband unruly crowds.