Chemical crowd control agents

Introduction

Chemical crowd control agents (CCCAs), also referred to as riot control agents, are widely used by civil authorities, government agencies and military forces to curtail civil disobedience gatherings and processions by large crowds or advances by enemy military forces. The idea behind their use is to discourage, scatter, or debilitate the crowd or enemy force so as to ensure minimal confrontation between the law enforcing agencies and the opposition. ¹ In the case of a violent crowd, the chemical agent should have a quick onset of effects, a short duration of action, and a good safety profile in order to avoid complications and permanent disabilities. ² However, in the case of a military operation, it may be ideal if the agent remains in the environment for weeks or months so as to hamper the progress of the enemy force. ³

The most frequently used CCCAs used to disperse large numbers of individuals into smaller, less destructive, and more easily controllable numbers are chloroacetophenone (CN), chlorobenzylidenemalononitrile (CS), dibenzoxazepine (CR), diphenylaminochloroarsine (DM), and oleoresin capsicum (OC). The noxious effects of CCCAs usually last from 15 to 45 min after the individual leaves the contaminated environment and cleans off any residual chemical particles. ³ These compounds are used as aerosolised solids that are functional and safe at low concentrations. However, these agents can prove fatal at high concentrations, especially if the person in contact has a prior chronic respiratory disease such as asthma. These agents can be scattered in the environment through pressurised canisters, explosive cartridges, hand grenades and bombs which may contribute to impact injuries in addition to the noxious stimuli caused by the chemical agents.

CCCAs produce unpleasant or obnoxious sensations due to their acute action on the nervous system resulting in lacrimation, burning sensations on various mucosal surfaces, blurred vision, blood-shot eyes, drooling, dermatitis, nausea, and vomiting. ⁴ These chemical agents also stimulate protective reflexes such as bronchoconstriction, sneezing, coughing, apnoea and rapid shallow breathing as a result of irritation of the airway passages.

Individuals suffering from the acute effects of CCCAs should immediately be brought into fresh air, rinse their eyes with normal saline, and remove any affected clothing. Severe symptoms may require treatment with supplemental oxygen or bronchodilators. ²

In this brief review, we discuss the emergency medical care needed by sufferers of acute CCCA exposure and raise important issues concerning toxicology, safety, and health.

History

The use of CCCAs dates back to 431–401 BC, when Thracian allies of Sparta overpowered the defenders of an Athenian fort during the Peloponnesian War by releasing fumes of burning coal, sulphur, and pitch in the environment. ⁵ Over the centuries strides in the field of chemistry led to the development of more sophisticated potential chemical weapons. In 1854, Sir Lyon Playfair, a notable chemist, proposed the use of cyanide-laden shells against a besieged fort in Sebastopol during the Crimean War but his proposal was discarded on the basis of being too inhumane. ⁶ Interestingly, numerous international conferences held at St Petersburg in 1868, Brussels in 1874, and The Hague in 1899 and 1907 forbade the use of chemical agents in war. ⁴ Despite these many prohibitions, chemical agents were extensively used during the First World War. The Germans tried out chemicals like dianisidine chlorosulfonate and xylyl bromide at first which proved to be unsuccessful. But later at the suggestion of Fritz Haber on 22 April 1915 they experimented with large cylinders containing chlorine gas near Ypres, Belgium, which proved to be effective. ⁷ Later during the war phosgene and mustard gas were also used to incapacitate troops. Mustard agent bombs were used not only by German forces but also by the Spanish and French forces in Morocco in 1925, the Italian forces in Ethiopia in 1935, and the Japanese forces in China in 1937 and 1938. ²

During the Iran–Iraq War in the 1980s, the Iraqi forces used nitrogen mustard very frequently which led to the death of approximately 40,000 Iranians. On 16 March 1988, the Iraqi forces also wiped out an entire Kurdish population using either a nerve or cyanide agent. ⁴

In 1993, the Chemical Weapons Treaty was convened. This treaty banned production, stockpiling, and use of lethal chemical weapons. A total of 130 countries signed the treaty. However, North Korea and Iraq refused to do so. ³

In October 2002, Chechen separatists held approximately 800 people as hostages in a theatre in Moscow, Russia. The Russian Federal Security Service released an opiate derivative into the building. As a result, 41 terrorists and 129 hostages lost their lives due to opiate toxicity. Only two of the hostages managed to survive the incident. ⁸

Chloroacetophenone (CN)

Chloroacetophenone was produced with the sole intention of using it as a riot control agent. It is more commonly referred to as tear gas and has been allotted the military designation CN. ⁹ It targets the mucous membranes of the eye and respiratory tracts. Respiratory symptoms can range from sneezing, coughing and nasal congestion to intense suffocation. CN can cause much graver ocular side effects than either CR gas or dibenzoxazepine, or CS gas, a cyanocarbon, due to its greater potency as a mucosal irritant of the eye. It produces pain and a burning sensation in the eyes but greater concentrations of CN can also lead to corneal oedema, conjunctival oedema, erosion or ulceration, chemosis, focal haemorrhages, lacrimation, iritis, blepharitis, and keratitis. Apart from being a potent ocular irritant, CN can also cause severe allergic contact dermatitis which may present as generalised pruritus, diffuse erythema, severe oedema, and vesication. The onset of these effects is immediate and can last up to 20 min after the individual is removed from the contaminated environment. ⁹

Chlorobenzylidenemalononitrile (CS)

In 1928, Carson and Stoughton first prepared CS and the compound is conveniently named after their initials. ¹⁰ Its persistence in the environment varies and it has a pepper-like odour and a burning acidic taste. CS has taken the place of CN and it is the most extensively used riot control agent.

CS irritates the mucous membranes due to its greater water solubility, causing a noticeable local inflammatory reaction within a matter of seconds of exposure. Conjunctivitis is particularly common at low concentrations of CS which resolves on its own within a period of hours. The cornea is not generally affected even at higher concentrations. The eye is more susceptible to injury when CS is used in an aerosolised form rather than an aqueous form. The acute dermatological side effects of CS can comprise a tingling sensation, erythema, blisters, bullous or eczematous dermatitis with a seropurulent exudate. Prolonged contact with CS can result in hypertrophic scar formation or severe burns. Additionally, more chronic dermatologic presentations of CS exposure consist of allergic contact dermatitis subsequent to repeated exposure, exacerbation of rosacea, and leukoderma. A wide spectrum of respiratory symptoms is also seen in individuals with exposure to CS. The respiratory pathologies include cough, dyspnoea, reactive airways dysfunction syndrome, hypersensitivity pneumonitis, bronchoconstriction, and laryngospasm.

Dibenzoxazepine (CR)

Dibenzoxazepine has been assigned the abbreviation CR by the military. The solution containing CR which is used as a CCCA comprises 0.1% CR dissolved in a solution of four-fifths of propylene glycol and one-fifth water. It is a particularly stable compound and may persist for longer periods of time than the other CCCAs. Its action is instantaneous. ⁹

Studies have revealed that the human eye is much more vulnerable to injury if CR is used in an aerosolised form rather than in a solution form. Dibenzoxazepine has a better safety profile in comparison to CN or CS given that the molar concentration of CR required to elicit threshold effects is considerably lower.

Diphenylaminochloroarsine (DM)

Diphenylaminochloroarsine has the common name adamsite and has been allotted the designation DM by the military. Previously, it was used in agriculture primarily as an effective insecticide. Exposure to the chemical results in extreme vomiting which is why it is disfavoured as a CCCA.

Similar to the previously discussed CCCAs, DM also causes ocular side effects such as lacrimation, blepharospasm, and eye pain. Furthermore, it is important to note that DM may also lead to the necrosis of the corneal epithelium which is a serious side effect of this agent. Dermatological findings may include erythema or skin necrosis.

Oleoresin capsicum (OC)

OC is a blend of numerous chemicals. It is extracted from chilli peppers and is responsible for a strong taste of pepper. At least 100 different compounds have been discovered in OC. Capsaicin is the major component present in the mixture. ⁹

Apart from the classical ocular side effects of all CCCAs like lacrimation, conjunctival inflammation, redness, excruciating pain, swelling, and blepharospasm, OC has the unique characteristic of causing a loss of the blink reflex for as long as five days after exposure. ⁹ Additionally, OC causes neurogenic inflammation and an inability to sense stimuli.

Contact on skin of aerosolised OC results in intense burning pain, tingling, allergic dermatitis, oedema, erythema, and blistering. OC is also believed to deplete the skin of numerous biochemical mediators such as substance P, somatostatin, prostaglandin, and acetylcholine.

Emergency medical management

Individuals who have been exposed to CCCAs should be treated in a well-ventilated hospital room. In addition, they should be isolated from other patients. The medical personnel should take precautionary measures such as wearing impermeable gloves and goggles while dealing with these patients. The patients should be asked to remove any clothing and to seal it in a plastic bag in order to prevent secondary contamination.

Cleansing with soap and water is debatable given the potential risk of the chemical agents dissolving in water and worsening the symptoms. Hot water carries the risk of vaporising the chemical agent which in turn could lead to secondary contamination. As a general rule, washing with water should be avoided unless the symptoms fail to go away.

The preferred management for the ocular symptoms is also controversial. ¹⁰ Some have suggested blowing dry air with a fan in order to vaporise the chemical particles. If this is being done, then it must be ensured there is no-one downwind of the fan in order to prevent the risk of secondary human exposure. ¹⁰ Others have suggested washing with normal saline. A slit-lamp examination of the eyes is also recommended in order to make sure that no residual chemical particle remains embedded on the surface which may cause prolonged irritation. ¹⁰ Administration of bronchodilators may be necessary if the patient had prior respiratory conditions which may have been exacerbated by the exposure to the chemical agent.

Issues in toxicology, safety, and health

The aim of using a CCCA is to temporarily debilitate the opposition by causing irritation of the eyes, respiratory tract, and skin. For contemporary CCCAs like CS and OC there is a huge difference between dosages that result in temporary irritation and dosages which cause grave adverse health effects. Although previously used CCCAs such as CN and DM have been largely replaced with these relatively safer compounds, toxicity can still occur especially when used inappropriately. This is why there has been continued resistance to the use of these agents in the past across the globe.

The adverse side effects are usually seen if a person has been exposed to the chemical in a closed space or if they have had repeated exposure to the chemical or if the person has been exposed to greater concentrations than normal. Law enforcing agencies are requested to keep these factors in mind while trying to handle civil unrest by shelling these agents in order to prevent loss of precious human lives.

Conclusion

Until effective but safer methods for crowd control are developed, physicians should be adequately equipped to deal with patients who have been in contact with the contemporary CCCAs. Prior physician training in handling such cases would help them to provide prompt and appropriate health care to the exposed patients. Law enforcement agencies should also be briefed on responsible usage and the importance of not using highly concentrated solutions of these CCCAs. Individuals with pulmonary, dermal and ocular pathologies should also be specifically advised to refrain from taking part in volatile processions. Individuals with persistent symptoms should be asked to report to their local hospital immediately in order to avoid any permanent disabilities. Only by spreading awareness regarding these CCCAs can we prevent unfortunate incidents.