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Riot control agents: The tear gases CN, CS and OC-a medical review
Abstract
2-Chloroacetophenone (CN), o-chlorobenzylidene malonitrile (CS) and oleoresin capsicum (OC) are common riot control agents. While serious systemic effects are uncommon, exposure to high concentrations may lead to severe complications and even death. The aim of this narrative review is to summarise all main aspects of the riot control agents CN, CS and OC toxicology, including mechanisms of toxicity, clinical features and management.
OVID MEDLINE and ISI Web of Science were searched for terms associated with CN, CS and OC toxicity in humans and those describing the mechanism of action, clinical features and treatment protocols.
CN, CS and OC are effective lacrimating agents; evidence for toxicity, as measured by the threshold for irritation, is greatest for CN, followed by CS and OC. Typically, ocular and respiratory tract irritation occurs within 20-60 s of exposure. Ocular effects involve blepharospasm, photophobia, conjunctivitis and periorbital oedema. Following inhalation, effects may include a stinging or burning sensation in the nose, tight chest, sore throat, coughing, dyspnoea and difficulty breathing. Dermal outcomes are variable, more severe for CN and include dermal irritation, bulla formation and subcutaneous oedema. Removal from the contaminated area and fresh air is a priority. There is no antidote; treatment consists of thorough decontamination and symptom-directed supportive care. Ocular exposure requires thorough eye decontamination, an eye exam and appropriate pain management. Monitoring and support of respiratory function is important in patients with significant respiratory symptoms. Standard treatment protocols may be required with patients with pre-existing respiratory conditions. Dermal exposures may require systemic steroids for patients who develop delayed contact dermatitis.
CN, CS and OC are effective riot control agents. In the majority of exposures, significant clinical effects are not anticipated. The irritant effects can be minimised both by rapid evacuation from sites of exposure, decontamination and appropriate supportive care.
... While the former includes personal defense sprays and gas cartridges, canisters, and grenades employed by law enforcement (Ilgaz et al., 2019), the latter contains dispersions generated as smokes, aerosol mists, or powder clouds (Ballantyne, 2006). Hand-held devices contain liquid formulations released through narrow or wide-angle pressurized sprays to incapacitate one person (Schep et al., 2015). On the other hand, canisters and grenades are a pyrotechnic mixture blended with a powder form that is aerosolized for dispersion as smokes (Olajos and Stopford, 2004;Rothenberg et al., 2016). ...
... The mechanism of action of tear gases occurs due to the activation of transient receptor potential (TRP) ion channels, a group of sensitizing chemosensory receptors located in peripheral nerve endings (Rothenberg et al., 2016;Frey et al., 2022). The TRP vanilloid (TRPV1), an agonist of OC, also known as capsaicin, and ankyrin (TRPA1) agonist of CS, CN, and CR, are two subfamilies of TRP ion channels (Schep et al., 2015). They are both expressed in the peripheral pain-sensing nociceptive nerves of the skin, the mucous membranes of the lung and upper and lower airways, and the ocular surface (cornea and conjunctiva) (Rothenberg et al., 2016). ...
... Capsaicin (C 18 H 27 NO 3 ), the main component of OC, has a melting and boiling point of 64°C and 210-220°C, respectively, and a molecular weight of 305.41. The threshold for ocular irritation is 0.002 mg/m 3 (Schep et al., 2015;Kim et al., 2016). ...
Riot Control Agents (RCAs) are chemical compounds used by law enforcement agencies to quell violent demonstrations as an alternative to lethal force and as part of police/military training. They are also known as tear gases because of the hallmark ocular irritation and lacrimation they cause. The most common RCAs include oleoresin capsicum (contained in Mace and pepper spray), chlorobenzylidene malononitrile, dibenzoxazepine, and chloroacetophenone (previously the main content of Mace); some of which have been in use for decades. Their immediate incapacitating effects are mediated through polymodal afferent fibers innervating the corneal surface, inducing the release of peptides that cause neurogenic inflammation. Although previously thought to have only transient effects on exposed patients more severe complications such as corneal stromal opacities, corneal neovascularization, neurotrophic keratopathy, conjunctival necrosis, and pseudopterygium can occur. Concerningly, the lack of research and specific therapies restrict the current management to decontamination and symptom-tailored support. This manuscript will provide an overview of the toxic mechanisms of RCAs, their clinical manifestations, and current therapy after exposure to tear gases.
... Controlling the body: of course pain, but not only pain Table 1 collects a brief summary of available contemporary non-lethal weapons already in use or in experimental stage with potential use as torture devices (National Research , 2003;Wright, 2002). Some of them are well-known and debated, like electro-shock implements (Dermengiu et al., 2008;Institute for Security Studies, 2016), sound weapons (Davison, 2009a;Volcler, 2013) or chemical riot control agents (Schep et al., 2015). ...
Torture, understood as a relationship of domination in which one person breaks the will and impedes the self-determination of another human being, taking control of all aspects of the victims’ life and trying to change the core elements of their identity to the perpetrator’s interests (Pérez-Sales, 2017), will increasingly come to be linked to new technologies, artificial intelligence, the use of media and internet, and to new forms of lethal and non-lethalweapons. The author reviews the implications of modern technology for the contemporary fight against torture and some of the emerging civil society initiatives that aim to face them.
... Chlorobenzylidene malononitrile (CS), named "CS" after its creators Corson and Stoughton who developed it in 1928, is the most commonly used tear gas used by law enforcement for crowd control today. It replaced CN as the main tear gas used by law enforcement due to its higher dispersal and reported lower toxicity (Gongwer et al. 1958;McNamara et al. 1969;Tidwell and Wills 2020;Schep et al. 2015). ...
Tear gases, or chemical demonstration control agents (DCA), were originally created as weapons that could severely disable or kill enemy troops. Though banned in war, these chemicals are still used in domestic policing. Here we review the available scientific literature on tear gas, summarizing findings from animal and environmental studies as well describing data from new human studies. We find a lack of scientific evidence supporting the safety of tear gas, especially regarding its long-term impacts on human health and the environment. Many of the available studies were published decades ago, and do not parse data by variables such as chemical type and exposure time, nor do they account for the diversity of individuals who are exposed to tear gas in real-life situations. Due to the dearth of scientific research and the misinterpretation of some of the available studies, we conclude that a serious reevaluation of chemical DCA safety and more comprehensive exposure follow-up studies are necessary.
Chemical warfare agents (CWAs) are among the most prominent threats to the human population, our peace, and social stability. Therefore, their detection and quantification are of utmost importance to ensure the security and protection of mankind. In recent years, significant developments have been made in supramolecular chemistry, analytical chemistry, and molecular sensors, which have improved our capability to detect CWAs. Fluorescent and colorimetric chemosensors are attractive tools that allow the selective, sensitive, cheap, portable, and real-time analysis of the potential presence of CWAs, where suitable combinations of selective recognition and transduction can be integrated. In this review, we provide a detailed discussion on recently reported molecular sensors with a specific focus on the sensing of each class of CWAs such as nerve agents, blister agents, blood agents, and other toxicants. We will also discuss the current technology used by military forces, and these discussions will include the type of instrumentation and established protocols. Finally, we will conclude this review with our outlook on the limitations and challenges in the area and summarize the potential of promising avenues for this field.
In this paper, a direct immersion solid‐phase microextraction procedure for the simultaneous analyses of four primary riot control agents: 2‐Chloroacetophenone, o‐chlorobenzylidene malonitrile, Dibenz (b, f)‐1,4‐Oxazepine, and oleoresin capsicum at μg·L−1 concentration from environmental water was developed. Several parameters that influence the extraction effectiveness were investigated, including fiber type, extraction temperature, extraction time, starring rate, and salinity. Under the recommended conditions, the optimized method had reasonable linearity and accuracy. The average recovery of this method ranged from 84% to 108.1%. The limit of detection for all the analytes ranged from 0.2 to 3 μg·L−1and the limit of quantification ranged from 1 to 10 μg·L−1, respectively. A relative standard deviation from 3.0% to 4.3% can be achieved depending on the compounds. The procedure was applied to analyze all the four riot control agents simultaneously in several environmental samples. This article is protected by copyright. All rights reserved
Sensory irritation is an acute adverse effect leading to temporary disability posed by riot control agents in various deployable forms are utilized by defense personal in violent mob attacks but their irreversible toxic effects and risk assessment have been a matter of concern. These intimidating risks of available riot control agents have led to exploring the pulmonary toxicity profile of the oil in water emulsion formulation developed for vicious crowd controls containing an irritant oleoresin capsicum, a malodorant (skatole), and a commercial dye, followed by characterization using standard methods. Nonlethal riot control combinational formulation (NCF) has been aimed to be the best possible low-lethal alternative for riot control measures. In this study, 30 min of acute inhalation exposure of NCF was given to Wistar rats and various respiratory parameters like lung dynamics, bronchoalveolar lavage fluid (BALF) cytological assays, pro-inflammatory cytokines estimation, antioxidant activity, collagen accumulation, cytotoxicity, in vivo lung imaging, western blot, histology of lung tissue, etc. were investigated to validate its potentiality and rate of irritation reversibility as nonlethal agents. An exaggerated physiological change like sensory irritation, changes in lung functional variables, increased pro-inflammatory cytokines, etc. were noticed initially without airway obstruction as the expression of nociceptive TRPV1 protein did not alter the physiological regulation of protective proteins like Nrf2 and HO-1 and also no abnormality was found in lung tissue architecture. In conclusion, it can be stated that this formulation can be explored as a nonlethal riot control agent intending to generate discomfort but with early reversibility of sensory irritation and no recurrence of toxicity.
Although beginning as medical support to SWAT teams, tactical emergency medical support (TEMS) now encompasses the provision of preventive, urgent, and emergent medical care during high-risk, extended-duration, and mission-driven law enforcement special operations. Recognizing the benefit of medical support in these volatile situations, the National Association of EMS Physicians endorsed the concept of integrating EMS capability into law enforcement special operations in 2001, and TEMS remains a dynamic and evolving discipline within EMS medicine.
Résumé
Les sprays irritants sont constitués de particules en suspension dans un liquide : capsaïcine (extraits de piments), parfois d’extraits de poivre, de moutarde ou de chlorobenzylidènemalononitrile (CS). En raison des symptômes incapacitants immédiats qu’ils induisent, ces sprays sont utilisés à des fins de neutralisation d’un individu. Bien que reconnues comme peu dangereuses, l’exposition directe et prolongée à ces substances provoque des symptômes cutanés, oculaires et respiratoires qui peuvent s’avérer gravissimes. Nous présentons deux cas d’exposition directe à une substance irritante, survenus dans des contextes d’agitation pathologique. Pour chaque sujet, aucune décontamination rapide du produit n’a été réalisée, engendrant l’apparition de complications sévères à type de brûlures. Ces éléments attirent l’attention sur la nécessité absolue de réaliser des soins efficaces dans les suites d’une telle exposition.
Absract. Arguments are presented in favor of the increasing relevance of irritants to ensure the fulfillment of tasks by military personnel of the Armed Forces of the Russian Federation, as well as the need to reassess the risks to human health arising from their use. The results of an information-analytical data on methods and adverse effects of irritant application for purposes which are not prohibited by the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction are presented. Modern ideas about molecular mechanisms of the effect of irritants on structures of the nervous system are considered, which are based on the fact that the provocative effect of irritants is realized by changing the permeability of cation channels of the transient receptor potential of type A1, expressed at the ends of sensitive neurons. The results of experimental and clinical studies of specific modulation of these channels using their natural and synthetic antagonists are analyzed. Structural formulas and basic pharmacological characteristics of the most active antagonists are given and the prospect of their use as a basis for the development of drugs for the treatment of irritant lesions is substantiated. The data on the use of solutions based on amphoteric and chelating agents for emergency treatment of skin areas infected with irritants is presented. A number of promising areas of research on the creation of effective medical means of protection against lesions by irritants has been identified.
CS gas (2-chlorobenzylidene malonitrile) is widely used in an incapacitant spray that causes intense lacrimation, blepharospasm and burning sensations in the throat and nose. Questions have been raised about its safety. We obtained information on short-term and long-term symptoms, and performed ear, nose and throat examinations and respirometry at 8–10 months, in 34 young adults who had been exposed to CS spray in a confined space during a confrontation with police. The group was subdivided into those who had been sprayed directly on the face ( n=10) and those exposed indirectly.
At one hour, all but 2 individuals still had symptoms; respiratory and oral symptoms were significantly more prevalent in the directly exposed group. At one month, only oral symptoms were significantly more prevalent. At 8–10 months, symptoms were still reported but there were no differences between the groups and clinical examinations revealed no specific abnormalities.
There was no convincing evidence of long-term physical sequelae from exposure to CS spray.
To the Editor.—
We read with great interest the several articles on cutaneous manifestations of violence in the June 1992 issue of the Archives.1-6 We would like to draw the physician's attention to another aspect pertinent to dermatologists: the cutaneous reactions produced by orthochlorobenzylidene malononitrile used as riot control agent and in self-defense sprays.
Report of Cases.—
In the last 3 years, 11 patients were hospitalized in our department for a bullous dermatitis after they had been sprayed with this agent. Nine of 11 patients were men and almost half of them were homeless, having been involved in criminal behavior. In five cases, the patients had already been exposed to self-defense sprays. Clinically, they presented with an erythematous dermatitis localized on the areas directly exposed to the spray (face, neck, and hands) but also on other parts reached by the agent flowing along the body (shoulders and trunk). Their
•Eight patients (five previously undescribed) died due to aspiration of pepper. Seven deaths involved homicides, and one death was accidental in a child with documented pica. The pepper was administered by the mothers in three children and by a foster mother, the mother's boyfriend, an adult male friend, and the child's godfather in one case each. Homicidal pepper aspiration shares many of the features of more conventional child abuse: in each instance, the child was being punished, four of the seven assailants initially gave incorrect histories, and four children were chronically abused. The facts that each death occurred in a different state and that five of the seven homicides occurred within the two years preceding the preparation of this report suggest that this form of child abuse is not confined to any single part of the country and may be increasing in frequency.
(AJDC 1988;142:633-636)
•Eight patients (five previously undescribed) died due to aspiration of pepper. Seven deaths involved homicides, and one death was accidental in a child with documented pica. The pepper was administered by the mothers in three children and by a foster mother, the mother's boyfriend, an adult male friend, and the child's godfather in one case each. Homicidal pepper aspiration shares many of the features of more conventional child abuse: in each instance, the child was being punished, four of the seven assailants initially gave incorrect histories, and four children were chronically abused. The facts that each death occurred in a different state and that five of the seven homicides occurred within the two years preceding the preparation of this report suggest that this form of child abuse is not confined to any single part of the country and may be increasing in frequency.
(AJDC 1988;142:633-636)
In the context of this review, civil unrest is defined as disharmony, expressive dissatisfaction and/or disagreement between members of a community, which leads to a situation of competitive aggression that may find expression as disruption of organisation, conflicts, damage to property and injuries. Such a breakdown of harmonious relationships, which may result in property damage and human injuries that may be threatening to life, varies in magnitude from participation of a very few individuals up to the involvement of large crowds of people, which may evolve into a full-scale riot. It is the latter situation often involving demonstrators, opposing groups and law enforcement personnel that can result in multiple casualties and present a very significant challenge to the resources of local healthcare institutions. The causation of civil unrest incidents is multifactorial and has generic, specific and potentiating elements. With the current national and international societal, political and discriminatory problems, it is likely that civil unrest incidents on both small and large scales will continue to occur at a high and possibly increasing rate on a worldwide basis, and for these not infrequent incidents, the medical community should be in a state of informed preparation. The circumstances of civil unrest incidents are very variable with respect to causation, overall magnitude, frequency, timing, geographical location, numbers of persons involved, demographics of participants, influence of extremists, confrontation with opposing groups and control measures used by law enforcement agencies.
Methods used by police and security forces for the control of civil unrest incidents, if advanced negotiations with organisers and verbal warnings have failed, fall basically into two categories: physical and chemical measures. Physical methods include restraint holds, truncheons, batons, mounted horses, projectiles (such as bean bags, plastic and rubber bullets), water cannons, tasers and (rarely) live ammunition. All of these physical measures are associated with pain and immobilisation, and there is a high potential for soft tissue and bone injuries. Some of the more severe physical methods, including plastic and rubber bullets, may cause lethal injuries. The basis for using chemicals in civil unrest incidents is that they cause distraction, transient harassment and incapacitation, temporary impairment of the conduct of coordinated tasks and cause a desire to vacate the area of unrest. Although screening smokes and malodors have sometimes been employed, the major group of chemicals used are peripheral chemosensory irritants (PCSIs), which reversibly interact with sensory nerve receptors in exposed skin and mucosal surfaces, resulting in the production of local uncomfortable sensations and associated reflexes. Major effects are on the eye, respiratory tract and (to a lesser degree) skin. Thus, the induced transient pain and discomfort in the eye, respiratory tract and skin, together with associated lacrimation, blepharospasm, rhinorrhoea, sialorrhoea, cough and breathing difficulties, produce temporary incapacitation and interference with the conduct of coordinated tasks, and form the basis for harassment of malefactors. Currently used peripheral chemosensory irritants are 1-chloroacetophenone, 2-chlorobenzylidene malononitrile, dibenz(b.f)-1,4-oxazepine, oleoresin capsicum and pelargonic acid vanillylamide. Depending on operational circumstances, irritants may be dispersed as a smoke, powder cloud, aerosol, vapour, or in solution; the mode of generation and dispersion of irritant can influence hazard. Brief acute exposure to chemosensory irritants produces effects that generally resolve within an hour, leaving no long-term sequelae. However, sustained exposure to high concentrations may produce tissue injury, notably to the eye, respiratory tract and skin. With solutions of sensory irritants, other formulation constituents may enhance PCSI toxicity or introduce additional local and/or systemic toxicity.
By the very circumstances of civil unrest incidents, injuries are inevitable, particularly when emotions are heightened and police and security forces have to resort to various chemical and/or physical means of control. Trauma may include slight to severe physical and/or chemical injuries, psychological problems and occasional deaths. Hospitals should be prepared for a wide range of casualties, and the fact that those seeking help will constitute a heterogeneous group, including wide age range, male, female, and individuals with pre-existing ill health. A major civil unrest incident necessitates that the local receiving hospital should be prepared and equipped for decontamination and triage processes. It is necessary to reassure patients who have been exposed to sensory irritants that the signs and symptoms are rapidly reversible, and do not result in long-term sequelae. With respect to chemical exposures, detailed evaluation should be given to possible ocular, cutaneous, respiratory and gastrointestinal effects. Also, exposure to chemosensory irritants results in transient increases in blood pressure, bradycardia and increased intraocular pressure. This indicates that those with cardiovascular diseases and glaucoma may be at increased risk for the development of complications. This article details the pharmacological, toxicological and clinical effects of chemicals used in civil disturbance control and discusses the management of contaminated individuals. Additionally, the potential for adverse effects from delivery systems and other physical restraint procedures is summarised.
Due to the emergency and specialised circumstances and conditions of a civil unrest incident, there is a clear need for advanced planning by healthcare institutions in the event that such an incident occurs in their catchment area. This should include ensuring a good information base, preparations for medical and support staff readiness, and availability of required equipment and medications. Ideally, planning, administration and coordination should be undertaken at both local (regional) and central (governmental) centres. Regional centres should have responsibilities for education, training, ensuring facilities and staffing are appropriate, and that adequate equipment and medicines are available. There should be cooperative interactions and communications with local police and other emergency services. Centrally directed functions should include ensuring adequacy of the information base, coordinating activities and agreeing approaches between the regional centres, and periodic audits of regional centres with respect to the staffing, facility, equipment and training needs. Also, there is a need for most countries to introduce detailed guidelines and formal (regulatory) schemes for the assessment of the safety-in-use of chemicals and the delivery systems that are to be used against heterogeneous human populations for the control of civil unrest incidents. Such regulatory approval schemes should also cover advisory functions for safe use and any required restrictions.
Irritant incapacitants, also called riot control agents, lacrimators and tear gases, are aerosol-dispersed chemicals that produce eye, nose, mouth, skin and respiratory tract irritation. Tear gas is the common name for substances that, in low concentrations, cause pain in the eyes, flow of tears and difficulty in keeping the eyes open. Only three agents are likely to be deployed: (i) 1-chloroacetophenone (CN); (ii) 2-chlorobenzylidene malononitrile (CS); or (iii) dibenz[b,f]-1,4-oxazepine (CR). CN is the most toxic lacrimator and at high concentrations has caused corneal epithelial damage and chemosis. It has accounted for at least five deaths, which have resulted from pulmonary injury and/or asphyxia. CS is a 10-times more potent lacrimator than CN but is less systemically toxic. CR is the most potent lacrimator with the least systemic toxicity and is highly stable.
CN, CS and CR cause almost instant pain in the eyes, excessive flow of tears and closure of the eyelids, and incapacitation of exposed individuals. Apart from the effects on the eyes, these agents also cause irritation in the nose and mouth, throat and airways and sometimes to the skin, particularly in moist and warm areas. In situations of massive exposure, tear gas, which is swallowed, may cause vomiting. Serious systemic toxicity is rare and occurs most frequently with CN; it is most likely to occur when these agents are used in very high concentrations within confined non-ventilated spaces. Based on the available toxicological and medical evidence, CS and CR have a large safety margin for life-threatening or irreversible toxic effects. There is no evidence that a healthy individual will experience long-term health effects from open-air exposures to CS or CR, although contamination with CR is less easy to remove.
Tear gas has gained widespread acceptance as a means of controlling civilian crowds and subduing barricaded criminals. The most widely used forms of tear gas have been o-chlorobenzylidenemalononitrile and ω-chloroacetophenone. Proponents of their use claim that, if used correctly, the noxious effects of exposure are transient and of no long-term consequences. The use of tear gas in recent situations of civil unrest, however, demonstrates that exposure to the weapon is difficult to control and indiscriminate, and the weapon is often not used correctly. Severe traumatic injury from exploding tear gas bombs as well as lethal toxic injury have been documented. Moreover, available toxicological data are deficient as to the potential of tear gas agents to cause long-term pulmonary, carcinogenic, and reproductive effects. Published and recent unpublished in vitro tests have shown o-chlorobenzylidenemalononitrile to be both clastogenic and mutagenic. Sadly, the nature of its use renders analytic epidemiologic investigation of exposed persons difficult. In 1969, eighty countries voted to include tear gas agents among chemical weapons banned under the Geneva Protocol. There is an ongoing need for investigation into the full toxicological potential of tear gas chemicals and renewed debate on whether their use can be condoned under any circumstances.
(JAMA. 1989;262:660-663)