Irritants - Riot Control Agents Clinical Presentation

The timing of symptom onset after exposure to tear gas (CS) varies, depending on the duration of exposure and the organ system involved. With dermal effects, for example, erythema may develop within a few minutes, whereas acute generalized exanthematous pustulosis may have a latency period of 1-2 weeks. Similarly, respiratory effects can occur immediately (eg, cough) or develop after about 3 weeks (eg, laryngeal obstruction). ^[3]  

Most cases are self-limited, lasting 15-30 minutes after clothing is removed and the person is in an open space. ^[2] Reconsider the diagnosis of riot control agent exposure if symptoms persist longer than 30 minutes. However, in one study, the majority of subjects who were directly sprayed with CS in the face still had respiratory and oral symptoms after 1 hour. ^[9]   

Typically, exposed persons feel a burning sensation in the eyes, nose, mouth, and even airway. The eye is the most sensitive organ involved and is the most immediately and severely affected of all the target organs. Eye involvement may include the following:

• Ocular pain, tearing, and severe blepharospasm are common; at high concentrations, 2-chloroacetophenone (CN) is known to cause corneal epithelial damage and chemosis.

• Conjunctival injection and periorbital edema may be noted

• More serious and even permanent eye injuries (eg, corneal abrasions, foreign bodies) can be caused by tear gas particles, other foreign particles, or the blast injury itself.

• Patients may complain of blindness because of the intense tearing and blepharospasm, but patients who can physically open their eyes have no significant change in visual acuity

Other manifestations are as follows:

• Nausea, vomiting, and diarrhea may occur
• Rhinorrhea, sneezing, and hypersalivation often occur as agents come in contact with sensitive mucous membranes.
• Patients also may report cough, chest tightness, dyspnea, and wheezing, but pulmonary function test results typically are not changed
• Exacerbation of a chronic pulmonary condition, such as asthma or chronic obstructive pulmonary disease, may occur
• Exercise exacerbates symptoms
• Psychological effects (eg, anxiety) also provoke increased response
• Tolerance to CS symptoms can develop with chronic low-grade exposures

Skin contact with a riot control agent results in erythema, tingling, and burning. Blistering may also occur after exposure to higher concentrations. Skin involvement tends to be more severe with CN, and may include irritation, bulla formation, and subcutaneous edema. ^[20] Dermal manifestations develop within minutes of exposure and last up to 1 hour after termination of exposure.

More severe skin injuries can occur in hot, humid environments with heavily sweating or wet patients or with prolonged or close-range exposures. First- or second-degree burns and delayed allergic contact dermatitis may be seen, especially with exposure to CN and CS.

Police and bystanders may be unintended victims of riot control agents. In a study by Watson and Rycroft, six police officers and one bystander developed contact dermatitis, leukoderma, exacerbation of seborrheic dermatitis, and aggravation of rosacea following exposure to CS. ^[21]

Serious effects, including death, have been reported. CN has accounted for five deaths due to pulmonary injury and/or asphyxia. A case report involved a 4-week-old infant who accidentally received a discharge of pepper spray (OC), which immediately led to respiratory distress, followed by apnea. The infant was resuscitated and ultimately recovered after much intensive care, including extracorporeal membrane oxygenation (ECMO). ^[22]

Severe effects (eg, pulmonary edema, chemical pneumonitis) usually occur only with prolonged exposure in an enclosed space. Such exposures can damage the respiratory tree. Upper airway mucosal necrosis and pulmonary edema have been reported.

Some studies have suggested that CS may be converted into cyanide in the peripheral tissues. However, the risk of cyanide toxicity seems to be minimal. ^[23]

There are limited data on the effects of tear gas during pregnancy, but the risk of fetal toxicity is thought to be minimal. There are no reports of tear gas in breast milk following exposure. ^[24]

Unintentional oral ingestions can occur, specifically in children. Abdominal cramps and diarrhea are common, but the ultimate course usually is uneventful. The lethal dose in one half of the exposed population (LD50) in animals is 200 mg/kg, which is an amount unlikely to be ingested.

Other gases irritating to the mucous membranes and respiratory system (eg, lewisite, phosgene oxime) may be confused with pulmonary irritants. Features that help with distinguishing these include the following:

• A history of gas exposure in use by law enforcement or military training suggests tear gas use.
• Eye symptoms are especially prominent in pulmonary irritant use.
• Significant respiratory findings are rare but may occur in high concentrations in an enclosed space, especially in pediatric and geriatric victims with preexisting comorbidities.

In a study of 2257 adults reporting exposure to tear gas during protests in Portland, Oregon in 2020, almost all respondents reported immediate health effects. In addition, 80.8% of participants reported delayed physical health issues 1 to 2 days after exposure. The most commonly reported delayed issues were related to lungs and/or chest and menstrual changes (eg, increased menstrual cramping, unusual spotting, increased bleeding), followed by gastrointestinal (eg, diarrhea, cramping), head, and eye issues. ^[15]  

Long-term effects, usually as a result of prolonged exposure, can include ophthalmological complications such as cataracts, glaucoma, and blindness, as well as pulmonary deterioration leading to respiratory failure. ^[7]

Physical findings in patients exposed to riot control irritants are as follows ^{[2, 4, 5, 6, 7, 10]} :

• Respiratory: Cough, chest tightness, sensation of suffocation, shortness of breath, increased respiratory rate, wheezing, rales, decrease in oxygen saturation, cyanosis, pulmonary edema, and respiratory arrest in young infants

• Cardiovascular: Tachycardia, hypertension (these are believed to be most likely a psychological response to the situations in which tear gases typically are used)

• Skin and mucous membranes: Erythema, pain, blistering of the skin, first- (possibly second-) degree burns of the skin

• Eyes: Conjunctival injection, redness, and irritation; corneal burns; pain; tearing; blurry vision; periorbital edema; lacrimation

• Oropharynx: Oral burns and irritation, sore throat, hoarseness, dysphagia, and hypersalivation

• Nasal: Rhinorrhea, burning, irritation, sneezing

Severity of manifestations varies with the age of the victim, comorbid factors, and duration of exposure.

 Short-term complications include the following ^{[2, 4, 7]} : 

• Pulmonary edema, bronchospasm, hemoptysis, chemical pneumonitis
• Hepatocellular damage
• Heart failure
• Second-degree burns
• Death

Long-term include the following ^{[2, 4, 7]} :

• Cataracts
• Glaucoma
• Blindness (note: hyphema, uveitis, necrotizing keratitis, secondary glaucoma, and cataracts have been reported, but since the exposure to the riot control agent was related to an explosive device, it is unclear whether these more serious complications were due to the agent or the delivery system. ^[2]
• Respiratory failure