Pharmacologic Inhibition of Transient Receptor Potential Ion Channel Ankyrin 1 Counteracts 2-Chlorobenzalmalononitrile Tear Gas Agent-Induced Cutaneous Injuries.

Deployment of the tear gas agent 2-chlorobenzalmalononitrile (CS) for riot control has significantly increased in recent years. The effects of CS have been believed to be transient and benign. However, CS induces severe pain, blepharospasm, lachrymation, airway obstruction, and skin blisters. Frequent injuries and hospitalizations have been reported after exposure. We have identified the sensory neuronal ion channel, transient receptor potential ankyrin 1 (TRPA1), as a key CS target resulting in acute irritation and pain and also as a mediator of neurogenic inflammation. Here, we examined the effects of pharmacologic TRPA1 inhibition on CS-induced cutaneous injury. We modeled CS-induced cutaneous injury by applying 10 µl CS agent [200 mM in dimethyl sulfoxide (DMSO)] to each side of the right ears of 8- to 9-week-old C57BL/6 male mice, whereas left ears were applied with solvent only (DMSO). The TRPA1 inhibitor HC-030031 or A-967079 was administered after CS exposure. CS exposure induced strong tissue swelling, plasma extravasation, and a dramatic increase in inflammatory cytokine levels in the mouse ear skin. We also showed that the effects of CS were not transient but caused persistent skin injuries. These injury parameters were reduced with TRPA1 inhibitor treatment. Further, we tested the pharmacologic activity of advanced TRPA1 antagonists in vitro. Our findings showed that TRPA1 is a crucial mediator of CS-induced nociception and tissue injury and that TRPA1 inhibitors are effective countermeasures that reduce key injury parameters when administered after exposure. Additional therapeutic efficacy studies with advanced TRPA1 antagonists and decontamination strategies are warranted. SIGNIFICANCE STATEMENT: 2-Chlorobenzalmalononitrile (CS) tear gas agent has been deployed as a crowd dispersion chemical agent in recent times. Exposure to CS tear gas agents has been believed to cause transient acute toxic effects that are minimal at most. Here we found that CS tear gas exposure causes both acute and persistent skin injuries and that treatment with transient receptor potential ion channel ankyrin 1 (TRPA1) antagonists ameliorated skin injuries.

Latent turn-on fluorescent probe for the detection of toxic malononitrile in water and its practical applications.

A latent turn-on fluorescent probe for the detection of malononitrile (NCCH2CN), a precursor of hydrogen cyanide (HCN) in the mammalian tissue metabolism, is developed based on reaction-based fluorophore generation for the first time. Malononitrile is utilized within a wide spectrum of academic and industrial applications, and it is a key reagent to make o-chlorobenzylidene malononitrile (CS gas; tear gas), which is used for riot control. Due to its extensive use as well as potential health risks and the environmental pollution, malononitrile monitoring method has been required. In this paper, we discovered that our key sensing platform, 6-(dimethylamino)-3-hydroxy-2-naphthaldehyde (named Mal-P1), responds sensitively and selectively towards malononitrile. The Knoevenagel condensation induced benzo [g]coumarin formation of Mal-P1 with malononitrile showed significant fluorescence turn-on response. In addition, Mal-P1 showed the malononitrile sensing ability in environmental samples (real water, CS gas) and imaging ability in biological sample (HeLa cell line) using fluorescence microscopy with low cytotoxicity. The successful demonstrations will facilitate further applications in a variety of fields.

Association between exposure to o-chlorobenzylidene malononitrile (CS riot control agent) and urinary metabolite 2-chlorohippuric acid in U.S. Army Mask Confidence Training.

This study was conducted among U.S. Army soldiers to evaluate the association between exposure to o-chlorobenzylidene malononitrile (CS riot control agent) and urinary metabolite 2-chlorohippuric acid (CHA) detected in test subjects (n = 87) after completion of Mask Confidence Training. CS exposures ranged 0.086-4.9 mg/m³ ([Formula: see text] = 2.7 mg/m³). CHA levels (corrected for creatinine) at 2-, 8-, 24-, and 30-hr post-exposure resulted in ranges of 94.6-1120 µg/g-cr ([Formula: see text] = 389 µg/g-cr), 15.80-1170 µg/g-cr ([Formula: see text] = 341 µg/g-cr), 4.00-53.1 µg/g-cr ([Formula: see text] = 19.3 µg/g-cr), and 1.99-28.4 µg/g-cr ([Formula: see text] = 10.6 µg/g-cr), respectively. Spearman's correlation revealed CHA levels strongly correlated with time sampled (r = -0.748, p < 0.05) and weakly correlated with CS concentration (r = 0.270, p < 0.05). A linear relationship was observed between CHA, CS concentration, and time of urine sample according to the following regression equation: ln(CHA, µg/g-cr) = 5.423 + 0.316 (CS conc., mg/m³) - 0.002 (time sampled), (R = 0.910, R² = 0.827, p < 0.05). This relationship suggests that CHA has the potential to be an effective retrospective indicator of CS exposure in future biomarker developments.

Can CS gas induce myocardial infarction?

"2-chlorobenzylidene malononitrile" also named CS gas is the most used riot-control agent in the world. Its reputation as the least toxic tear gas explains its large use by different authorities. Early exposure to CS spray commonly induces visual irritation, skin reactions, with increased mucous secretion in order to temporarily incapacitate targeted people. However, there is a large agreement that safety data of this product is limited and further studies need to be performed since serious problems could occur after heavy exposure such as loss of consciousness, laryngospasm, pulmonary edema and hemorrhage... Herein, we report a case of a young man who had acute myocardial infarction with serious cardiac sequelae after exposure to tear gas. To our knowledge, this is the second case since forty years in the literature that directly links documented acute heart infarction to CS gas exposure.

Can CS gas induce myocardial infarction?

"2-chlorobenzylidene malononitrile" also named CS gas is the most used riot-control agent in the world. Its reputation as the least toxic tear gas explains its large use by different authorities. Early exposure to CS spray commonly induces visual irritation, skin reactions, with increased mucous secretion in order to temporarily incapacitate targeted people. However, there is a large agreement that safety data of this product is limited and further studies need to be performed since serious problems could occur after heavy exposure such as loss of consciousness, laryngospasm, pulmonary edema and hemorrhage... Herein, we report a case of a young man who had acute myocardial infarction with serious cardiac sequelae after exposure to tear gas. To our knowledge, this is the second case since forty years in the literature that directly links documented acute heart infarction to CS gas exposure.

Chlorobenzylidene malononitrile tear gas exposure: Rinsing with amphoteric, hypertonic, and chelating solution.

OBJECTIVE: Chlorobenzylidene malononitrile (CS) is the tear gas used by the police. The aim was to evaluate an amphoteric, hypertonic, and chelating rinsing solution in CS exposure. METHODS: The first (CS) group of six police officers was exposed to CS only. The second (preexposure) group of eight sprayed their faces with an aqueous, hypertonic, amphoteric, and chelating solution before CS exposure. The third (postexposure) group of eight sprayed their faces with an aqueous, hypertonic, amphoteric, and chelating solution after CS exposure. The time between exiting the CS cloud and arriving at the "ready for action" checkpoint was measured. Their facial pain both inside the CS cloud and at the checkpoint was assessed (0-10 points). RESULTS: The pain level inside the CS cloud was significantly lower in the preexposed group (5.6 ± 1.1; p = 0.01) than in the CS group (9.7 ± 0.5) and in the postexposure group (9.1 ± 0.4) where it was similar. The time interval between CS exposure and arrival at the checkpoint in the preexposure group (1:26 ± 0:44 min) was significantly shorter than both in the CS group (2:28 ± 0:25 min; p = 0.04) and postexposure group (2:30 ± 0:48 min; p = 0.02) where it was not different. The residual pain at the checkpoint in the preexposure (1.1 ± 0.4) and postexposure (1.4 ± 0.7) groups was similar with a significant lower pain level than in the CS group (2.3 ± 0.5; p = 0.02). CONCLUSION: CS decontamination with an aqueous, hypertonic, amphoteric, and chelating solution reduces facial pain, whereas prevention with it reduces pain and recovery time.

Towards Development of a Dermal Pain Model: In Vitro Activation of Rat and Human Transient Receptor Potential Ankyrin Repeat 1 and Safe Dermal Injection of o-Chlorobenzylidene Malononitrile to Rat.

During clinical development of analgesics, it is important to have access to pharmacologically specific human pain models. o-Chlorobenzylidene malononitrile (CS) is a selective and potent agonist of the transient receptor potential ankyrin repeat 1 (TRPA1), which is a transducer molecule in nociceptors sensing reactive chemical species. While CS has been subject to extensive toxicological investigations in animals and human beings, its effects on intradermal or subcutaneous injection have not previously been reported. We have investigated the potential of CS to be used as an agonist on TRPA1 in human experimental pain studies. A calcium influx assay was used to confirm the capacity of CS to activate TRPA1 with >100,000 times the selectivity over the transient receptor potential vanilloid receptor 1. CS dose-dependently (EC50 0.9 µM) released calcitonin gene-related peptide in rat dorsal root ganglion cultures, supporting involvement in pain signalling. In a local tolerance study, injection of a single intradermal dose of 20 mM CS to rats resulted in superficial, circular crusts at the injection sites after approximately 4 days. The histopathology evaluation revealed a mild, acute inflammatory reaction in the epidermis and dermis at the intradermal CS injection site 1 day after administration. After 14 days, the epidermal epithelium was fully restored. The symptoms were not considered to be adverse, and it is suggested that doses up to 20 µL of 20 mM CS can be safely administered to human beings. In conclusion, our data support development of a CS human dermal pain model.

The pathology of lethal exposure to the Riot Control Agents: towards a forensics-based methodology for determining misuse.

The aim of this is to review deaths associated with the use of Riot Control Agents (RCAs) and to assess how the presenting pathologies is such cases may better inform cause of death conclusions upon autopsy. We also sought to present which additional steps should be added to the Minnesota protocol and the European harmonization of medico-legal autopsy rules in suspected cases of deaths associated with the use of RCAs. We included 10 lethal cases in our study. In three cases, RCAs were found to be the sole cause of death, in three cases RCAs were ruled a secondary cause of death due asphyxia or asthma subsequent to exposure to RCAs and in four cases RCAs were contributory factors to death. In three cases the responsible agents were identified as Chloroacetophenone (CN), Chlorobenzylidene malononitrile (CS) and Oleoresin capsicum (OC) and in the remaining 7 cases, the agent was OC alone. As there are no specific findings in suspected cases of death associated with RCA use, establishing cause of death and whether RCAs are the sole cause or only a contributory factor will be based on the elimination of other possible causes of death. For this reason, a specifically structured autopsy is essential. This specifically structured autopsy should contain basic principles of the Minnesota Protocol and the European harmonization of medico-legal autopsy rules with the following additional steps taken: examination of clothing, eyes, and skin; examination of pharyngeal, tracheobronchial, and eusophegeal mucosas; and a thorough recording of the steps taken by the party conducting the arrest, including other possible causes of in-custody death, as well as a detailed medical history of the deceased.

Exposure to the riot control agent CS and potential health effects: a systematic review of the evidence.

o-Chlorobenzylidene malononitrile (CS) is one of the most extensively used riot control agents. Our aim was to conduct a systematic review of the potential health effects related to CS exposure. We searched for papers in English between 1991 and 2014. Thirty five (35) studies (25 case reports, seven descriptive studies and three analytical studies) were included in the review. In the twenty five case reports/series 90 cases of exposure to CS and their clinical effects are presented. Their mean age was 25.7 years and 62.0% were males. In addition, 61% of the cases described dermal, 40% respiratory, 57% ocular clinical effects. Life threatening situations as well as long-term health effects were found and were related with exposure to confined/enclosed space. Descriptive and analytical studies have shown attack rates ranging from 12% to 40%. Subjects who were sprayed by the police more often needed special treatment and reported adverse health effects. Apart from transient clinical effects, CS could have lasting and serious effects on human health. Better surveillance of the subjects exposed to CS and completion of cohort studies among exposed populations will illuminate the spectrum of the health effects of exposure to CS.

Riot control agents: the tear gases CN, CS and OC-a medical review.

INTRODUCTION: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

O-chlorobenzylidene malononitrile (CS riot control agent) associated acute respiratory illnesses in a U.S. Army Basic Combat Training cohort.

Acute respiratory illnesses (ARIs) are among the leading causes for hospital visits in U.S. military training populations and historically peak during U.S. Army Basic Combat Training (BCT) following mandatory exposure to the riot control agent o-chlorobenzylidene malononitrile (CS). This observational prospective cohort studied the association between CS exposures and ARI-related health outcomes in 6,723 U.S. Army recruits attending BCT at Fort Jackson, South Carolina from August 1 to September 25, 2012 by capturing and linking the incidence of ARI before and after the mask confidence chamber to CS exposure data. Recruits had a significantly higher risk (risk ratio = 2.44; 95% confidence interval = 1.74, 3.43) of being diagnosed with ARI following exposure to CS compared to the period of training preceding exposure, and incidence of ARI after CS exposure was dependent on the CS exposure concentration (p = 0.03). There was a significant pre-/postexposure ARI difference across all CS concentration levels (p < 0.01), however, no significant differences were detected among these rate ratios (p = 0.72). As CS exposure is positively associated with ARI health outcomes in this population, interventions designed to reduce respiratory exposures could result in decreased hospital burden and lost training time in the U.S. Army BCT population.

Exposición a gas CS: a propósito de un caso peculiar / Exposure to CS gas: Case study

El gas CS (o-clorobenzolideno malononitrilo) se incluye dentro del grupo de los gases lacrimógenos. La exposición a dicho gas ocurre durante su empleo como gas de defensa o antidisturbios, así como durante el entrenamiento rutinario de las fuerzas de choque especializadas. Su acción tóxica es ejercida a través de un efecto irritante sobre piel y mucosas, así como por mecanismos inmunoalérgicos. Presentamos el caso de un paciente de 24 años, perteneciente a una fuerza de choque, que consultó por lesiones cutáneas luego de una exposición a humo y dispersión de polvo de una granada de gas CS durante ejercicios de entrenamiento. Clínicamente se presentó características peculiares, referidas a sus manifestaciones cutáneas, localización y severidad de las mismas. Se analiza la etiopatogenia de las lesiones y los posibles mecanismos involucrados, diagnósticos diferenciales, así como los pilares del tratamiento frente a una exposición a gas CS...

O-chlorobenzylidene malononitrile (CS riot control agent) exposure in a U.S. Army basic combat training cohort.

All U.S. Army soldiers participate in mask confidence training during initial military training and periodically throughout their careers. Training is conducted by dispersing the riot control agent, o-chlorobenzylidene malononitrile (CS), in a relatively air-tight structure where soldiers enter and conduct a series of exercises that culminate with mask removal. The study described here quantified CS concentrations experienced by 6,723 trainees and seven chamber operators during U.S. Army basic combat training at Fort Jackson, South Carolina, from August 1 to September 25, 2012. All 6,723 trainees were potentially exposed to CS concentrations exceeding the American Conference of Governmental Industrial Hygienists threshold limit value-ceiling (TLV-C) (0.39 mg/m3), 6,589 of which were potentially exposed to concentrations exceeding the value deemed immediately dangerous to life and health (IDLH) (2.0 mg/m3) by the National Institute for Occupational Safety and Health. All chamber operators were exposed to concentrations exceeding both the TLV-C and the IDLH.

Effects of incapacitant spray deployed in the restraint and arrest of detainees in the Metropolitan Police Service area, London, UK: a prospective study.

PURPOSE: In the United Kingdom (UK) police restraint and control of detainees is undertaken by assorted means. Two types of incapacitant spray (IS) are approved by the UK Home Office for use: CS (o-chlorobenzylidine malononitrile, dissolved in an organic solvent--methyl iso-butyl ketone and pelargonic acid vanillyamide (PAVA). The aim of this study was to document the effects of incapacitant sprays, by symptom assessment and medical examination, within a few hours of deployment. METHODS: A detailed proforma was produced to explore the nature of the arrest, the nature of exposure to the incapacitant spray, the type of incapacitant spray, the symptoms experienced and the medical findings. RESULTS: 99 proformas were completed. 74 % were completed by detainees and 26 % were completed by police officers. 88 % were exposed to CS spray, the remainder to PAVA spray. The mean time of assessment after exposure was 2.8 ± 2.33 h (mean ± SD). The most frequent sites of IS contact were the face and scalp (n = 78), and exposure to the left and right eyes (n = 32). The most common symptoms were: painful eyes (n = 68); red eyes (n = 58); runny nose (n = 59); lacrimation (n = 55); nasal discomfort (n = 52); skin irritation (n = 49); and skin burning (n = 45). The most common medical findings were: conjunctival erythema (n = 34); skin erythema (n = 21); and rhinorrhea (n = 20). CONCLUSIONS: Symptoms and signs of exposure to IS lasted longer than was expected (a mean of 2.8 h). Approximately 30 % of those exposed had ocular effects and 20 % had skin effects. The findings of this study will enable the guidelines on the expected effects and duration of symptoms resulting from exposure to incapacitant sprays to be reviewed and suggestions for their management to be refined.

The development of an analytical method for urinary metabolites of the riot control agent 2-chlorobenzylidene malononitrile (CS).

The analysis of biomedical samples such as urine and blood can provide evidence of exposure to chemicals for a range of applications including occupational exposure monitoring, detection of drugs of abuse, performance enhancement in sport and investigations of poisoning and incapacitation. This paper reports the development of an analytical method for two suspected urinary metabolites of the riot control agent 2-chlorobenzylidene malononitrile (CS): 2-chlorohippuric acid and 2-chlorobenzyl-N-acetylcysteine. 2-Chlorohippuric acid was identified in all 2h post-exposure samples from a set of urine samples taken from army recruits exposed to low levels of thermally dispersed CS during training. 2-Chlorobenzyl-N-acetylcysteine, a metabolite known to be formed in the rat, was not identified in any of the samples. The lower limit of detection (LLOD) for 2-chlorohippuric acid and 2-chlorobenzyl-N-acetylcysteine was 1ng/ml and 0.5ng/ml in pooled urine from the pre-exposed subjects. 2-Chlorohippuric acid was rapidly excreted but was detectable in the urine of 17 of the 19 subjects tested 20h after exposure.

Evaluation of CS (o-chlorobenzylidene malononitrile) concentrations during U.S. Army mask confidence training.

All soldiers in the U.S. Army are required to complete mask confidence training with o-chlorobenzylidene malononitrile (CS). To instill confidence in the protective capability of the military protective mask, CS is thermally dispersed in a room where soldiers wearing military protective masks are required to conduct various physical exercises, break the seal of their mask, speak, and remove their mask. Soldiers immediately feel the irritating effects of CS when the seal of the mask is broken, which reinforces the mask's ability to shield the soldier from airborne chemical hazards. In the study described in this article, the authors examined the CS concentration inside a mask confidence chamber operated in accordance with U.S. Army training guidelines. The daily average CS concentrations ranged from 2.33-3.29 mg/m3 and exceeded the threshold limit value ceiling, the recommended exposure limit ceiling, and the concentration deemed immediately dangerous to life and health. The minimum and maximum CS concentration used during mask confidence training should be evaluated.

Towards evidence-based emergency medicine: Best BETs from the Manchester Royal Infirmary. BET 1: the best treatment for eye irritation caused by CS spray.

A short-cut review was performed to evaluate whether irrigation or active blown air was the most effective treatment for CS gas irritation of the eyes. No published studies have answered this question. The clinical bottom line is that either treatment could be used to relieve eye symptoms after CS gas exposure.