The use of chemical incapacitant sprays: a review

CHEMICAL INCAPACITANTS The chemical incapacitants are a group of chemicals including 2-chlorobenzylidene malononitrile (CS) (Fig. 1), 1-chloroacetophenone (CN; the main constituent of Mace), and dibenzoxazepine (CR). All of these are irritant to the eyes, skin, and respiratory tract, and can therefore be used to temporarily incapacitate (Table 1). CN was first marketed as a personal defense spray in 1965 under the brand name Mace and this term is now (incorrectly) used in some circles as a generic term for all personal defense sprays. Each of these compounds has a different toxicity profile; for example, CS is a much more potent lacrimatory agent than CN. It is generally accepted that CN is the most injurious, CS being reputedly the safest. Several cases of death in adults have been attributed to the use of CN. As a consequence of its toxicity, CN is now used less frequently than either CS or OC. CS spray has been used as a chemical incapacitant since the 1950s, and it is legally available in most states of the United States for use by the general public, although possession and discharge by members of the general public in the United Kingdom still constitutes a legal offense under Section 5 of the Firearms Act (1968). It has been used by police forces in the United Kingdom since 1996, after strict guidelines for its use were developed. However, the question of safety of CS use has been raised in several arenas over the years, and a recent editorial in The Lancet called for a moratorium on its use. The incidence of complaints about its use by the police has increased steadily since its introduction. Pepper (oleoresin capsicum [OC]) sprays are available commercially in the United States, and are advertised as “legal, non-lethal self-protection devices,” but similar concerns about their usage exist. Pepper spray has been suggested as a possible alternative chemical incapacitant for use by police forces in the United Kingdom and Europe.