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

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.

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.

Potency of irritation by benzylidenemalononitriles in humans correlates with TRPA1 ion channel activation

We show that the physiological activity of solid aerosolized benzylidenemalononitriles (BMNs) including 'tear gas' (CS) in historic human volunteer trials correlates with activation of the human transient receptor potential ankyrin 1 ion channel (hTRPA1). This suggests that the irritation caused by the most potent of these compounds results from activation of this channel. We prepared 50 BMNs and measured their hTRPA1 agonist potencies. A mechanism of action consistent with their physiological activity, involving their dissolution in water on contaminated body surfaces, cell membrane penetration and reversible thiolation by a cysteine residue of hTRPA1, supported by data from nuclear magnetic resonance experiments with a model thiol, explains the structure-activity relationships. The correlation provides evidence that hTRPA1 is a receptor for irritants on nociceptive neurons involved in pain perception; thus, its activation in the eye, nose, mouth and skin would explain the symptoms of lachrymation, sneezing, coughing and stinging, respectively. The structure-activity results and the use of the BMNs as pharmacological tools in future by other researchers may contribute to a better understanding of the TRPA1 channel in humans (and other animals) and help facilitate the discovery of treatments for human diseases involving this receptor.