Acute effects of the potent lacrimator o-chlorobenzylidene malononitrile (CS) tear gas

1. The use of tear gas to control civil unrest is accepted practice by government authorities worldwide. It is rarely used in Hong Kong but during a recent riot at a Vietnamese detention centre large quantities were used and this was cause for some concern. 2. All patients presenting to the British Red Cross Clinic after the incident were seen by one of the authors. To establish if exposure to tear gas had serious effects on the health of the detainees, the case records of the 184 patients with symptoms consistent with CS exposure were reviewed 2 months later. 3. The most common complaints were burns (52%), cough (38%), headache (29%), shortness of breath (21%), chest pain (19%), sore throat (15%) and fever (13%). However, the only common findings on examination by a physician were burns (52%) and an inflamed throat (27%). All burns could be categorised as "minor' according to the American Burns Association classification and all were consistent with CS gas exposure. 4. Some patients complained of other symptoms that had not been previously reported in the literature, such as haemoptysis (8%) and haematemesis (4%), but these were only confirmed in one patient. 5. The majority of patients had recovered within 2 weeks of exposure although one asthmatic patient complained of shortness of breath lasting for 33 days and a sore throat lasting for 38 days after the incident. She had abnormally low peak expiratory flow readings, but had a clinical history of asthma. 6. No serious sequelae were encountered, but the incidence of burns in these patients was higher than would be expected from a review of the literature. However, very little data on the effects of tear gas in a riot situation has been published. There have been reports of high concentrations of CS gas causing reactive airways dysfunction but this was not seen in our group of patients.

Acute mass burns caused by o-chlorobenzylidene malononitrile (CS) tear gas

The use of tear gas in controlling riots has been an accepted practice in many countries for the past four decades. In a recent event, a large quantity of tear-gas canisters were used during a situation of unrest in a Hong Kong Refugees' Detention Centre. We report 96 cases of acute burn injury as an unpredicted side effect of o-chlorobenzylidene malononitrile (CS) tear gas. There were 47 females and 49 males with an age ranging between < 1 to 51 years. These burns were categorized as minor burns, with the total body surface area (TBSA) ranging from 1 to 8 per cent with mean percentage of 3. Most of the patients sustained superficial or partial-skin thickness injuries. Only two patients were admitted to the Prince of Wales Hospital Burns Centre because of deeper burns; debridement and skin grafting was required in one of them. The mechanism of burn injury was due to the flame generated from the grenade explosion, direct contact between the hot canister and the victim's skin, and the effect of the chemical powder inside the canisters when it splashed onto the victim's body. We suggest that the noxious transient effects of tear gas are underestimated, furthermore varying cutaneous effects and deep burns may result from its uncontrolled use during riots. There is a continuing need to reassess the potential toxic effects of CS tear gas as a riot control agent and to debate whether its future use can be condoned under any circumstances.

Personal aerosol protection devices: caring for victims of exposure

The increased incidence of violence in our society has led to a concern for personal safety. For self-protection, many individuals are turning to personal aerosol protection devices (PAPDs), which are readily accessible to the general public. The greater use and misuse of these noxious chemicals has led to an increase in injuries associated with exposure. Health care providers need to be aware of the modes of action of PAPDs, the presenting exposure symptoms, first aid measures, and decontamination procedures of the environment and the victim's belongings. This article provides a thorough discussion of PAPDs and will assist the clinician in delivering primary care and health education to victims of PAPD exposures.

[Lymphocyte stimulation test, a possible alternative for verifying chloroacetophenone sensitization]

We report on a case of pronounced sensitization to chloroacetophenone tear gas that developed after repeated occupational skin exposure in a 57-year-old police officer. Mainly in the presence of moisture and occlusion, cutaneous application of chloroacetophenone leads to severe irritant, and often also allergic, skin reactions. In patch testing the demonstration of allergic contact dermatitis in response to chloroacetophenone is hampered by the irritative potential of this substance even at low concentrations. This diagnostic bias can be overcome by the lymphocyte proliferation assay.

[The gas weapon--a new problem for forensic toxicology]

Current status of the problem of toxicologic assessment of irritants used for gas weapon charge is presented, classification and parameters of toxicity of clinical picture in poisoning with, and mechanisms of toxic action of irritants are described. Trends in research aimed at improvement of forensic medical diagnosis of lesions caused by irritants are discussed.

[Keratopathy due to a spray]

The paper presents seven cases of corneo-conjunctival lesions produced by anti-aggressional spray. The corneal lesions were superficial and do not exceed in depth the Bowman membrane. Besides the ocular lesions, the patients presented irritative cough and general manifestations represented by a transient motor deficit, which produced the decrease of the defense capabilities during 15-30 minutes. The ocular lesions had a favourable evolution, excepting two cases with more severe evolution.

[Tear gas and eye injuries]

In the course of the last year, the Eye Clinic, Ullevål hospital has treated six cases of corneal injury caused by violent use of tear gas spray cannisters. In some cases there was total abrasion of the corneal epithelium, which could take several weeks to heal. We want to draw attention to this "weapon", the use of which seems to be spreading among young people.

[Contact allergies to CN and CS ("tear gas") in participants in demonstrations]

56 occasional demonstrators were interviewed with regard to former skin contact with omega-chloroacetophenone (CN) or ortho-chlorobenzylidene malononitrile (CS). 33 persons (59%) reported skin reactions of various kinds. Patch testing with CN, the structurally related preservative chloroacetamide, and CS revealed clinically relevant reactions to CN in 3 cases and questionable positive reaction to CS in one case. 8 further patients showed mild reactions to CN and CS. We did not find any indication of cross reactions between CN and chloroacetamide.

Tear gas--harassing agent or toxic chemical weapon?

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 omega-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.

[CS tear gas spray as an injurious agent. Clinical aspects]

Eight cases are described, in which illegally imported CS-tear gas spray ("self-defence spray") were used in connection with malice or robbery. Analysis of the content of the sprays revealed small amounts of CS (0.2 per cent), but large amounts of solvents and propellants. The latter are presumed to have contributed to the symptoms. Exposure to CS-tear gas spray is usually harmless, but skin manifestations such as ulcerations, Quincke-like oedema in the face and allergic dermatitis have been reported by other authors. Theoretically, CS-particles may adhere to the cornea. Examination of the eye is therefore recommended.

Medical problems and criteria regarding the use of tear gas by police

Litigation against police agencies for the use and misuse of control agents and procedures has become an important issue for the forensic medical specialist and expert witness. As police technology improves, it becomes apparent that more information for forensic experts will be required in this area. One such area of concern is the use of tear gas by police. This paper addresses the basic types of gas in terms of their chemistry, uses, and medical side effects and complications. Two types of gases--namely, chloroacetophenone (CN) and orthochlorobenzylidenemalontrile (CS)--are discussed in terms of basic properties, unique advantages, and possible harm to the body. CN and CS are relatively safe agents that can be used to control the behavior of a dangerous person. Clinical examples of their use and misuse by police are also reported. Specific guidelines are offered to help ensure a proper assessment of the dangerous person and to protect the health and lives of police personnel, perpetrators, and others exposed to the tear gas. Forensic experts called to testify about the behavior of the disturbed person or to assess the appropriateness of action taken to subdue that person must become more aware of the technology employed by police agencies to accomplish this particular job of protecting public safety.

[Contact allergy to CN and CS tear gas]

Tear gases are used as riot control agents on account of their irritant properties. Five cases of allergic contact dermatitis due to omega-chloroacetophenone (CN) and one case additionally due to 2-chlorobenzylidene-malonitrile (CS) are reported.