Medical Aspects of Chemical Warfare (2008) - The Black Vault

Riot Control Agentsal 27 reported the pyrolytic decomposition products ofCS as CS, CO, CO 2, H 2O, HCl, HCN, NH 3, N 2O 2andC 2H 2. Further research by Kluchinsky et al 28–30 during2000 and 2001 using heat-dispersed CS canisters (Figures13-2 and 13-3) identified many additional thermaldegradation products by trapping the contaminantson a polytetrafluoroethylene filter and analyzing themby open tubular gas chromatography coupled to massspectrometry. Compounds observed in addition toCS and its isomer 4-chlorobenzylidenemalononitrileincluded 2-chlorobenzaldehyde, 2-chlorobenzonitrile,quinoline, 2-chlorobenzylcyanide, 1,2-dicyanobenzene,3-(2-chlorophenyl)propynenitrile, cis- and transisomersof 2-chlorocinnamonitrile, 2,2-dicyano-3-(2-chlorophenyl)oxirane, 2-chlorodihydrocinnamonitrile,benzylidenemalononitrile, cis- and trans- isomersof 2-cyanocinnamonitrile, 2-chlorobenzylmalononitrile,3-quinoline carbonitrile, and 3-isoquinolinecarbonitrile. 28–30The CS-derived compounds observed were likelyproduced through rearrangements and by loss of cyanoand chlorine substituents present on the parent CScompound. Especially noteworthy is the formation of3-(2-chlorophenyl)propynenitrile, which is indicativeof a loss of cyanide from the CS molecule. Althoughthe metabolic effects of cyanide have been addressed inthe open literature, the metabolic effects of trans- andcis-2-cyanocinnamonitrile, 3-quinoline carbonitrile,and 3-isoquinoline carbonitrile, which appear to beproduced through free radical mechanisms, lack sufficientinvestigation.Detailed sampling under similar conditions andanalysis for inorganic salts (using the NIOSH methods7904 and 6010 [modified] for HCN and 7903 forHCl) showed that HCN and HCl were present in airsamples collected during high-temperature dispersionof CS. 28 The concentration of HCN identified duringthe dispersion of two CS canisters inside a 240 m 3 RCAtraining chamber (Figure 13-2 and 13-3) was found tobe above the exposure level guidelines recommendedby the American Conference of Governmental IndustrialHygienists (ACGIH) and NIOSH.The study group hypothesized that the formationof potentially harmful CS-derived compoundsproduced through free radical intermediates (cis- andtrans- isomers of 2-cyanocinnamonitrile, 3-quinolinecarbonitrile, and 3-isoquinoline carbonitrile), and therelease of HCN, evidenced by the presence of 3-(2-chlorophenyl)propynenitrile,was temperature dependent.This hypothesis led to another study in which CS washeated in an inert atmosphere using a tube furnace. 30Pure CS was used so that the effect of temperatureon CS could be analyzed independently of the othercompounds present in canisters, such as potassiumchlorate, sugar, magnesium carbonate, and nitrocellulose.It was assumed that the tube furnace’s effecton the production of CS-derived compounds couldbe generalized to that formed by high-temperaturedispersion of CS canisters. By assuming that neat CSbehaved in a similar manner as that found in canistersdispersing at an average temperature of 798°C (Figure13-5), standardizing residence time in the tube furnace,and using an inert nitrogen carrier gas at a constantflow, it was shown that many of the organic degradationproducts observed earlier in a field environmentwere produced through heating. Additionally, thestudy identified tube-furnace–induced temperatureranges associated with the formation of the CS-derivedcompounds.However, generalizing conclusions drawn fromlaboratory-based CS data to exposures from thermaldispersion of CS in a field environment must be donewith caution. CS must be deployed appropriately duringoperations and training to ensure optimal safety.Use of CS capsules (Figure 13-4) is the only acceptedmethod of CS dispersal for mask confidence trainingperformed in an enclosed space (eg, tent, chamber, orbuilding).Clinical EffectsAcute EffectsCS is a peripheral sensory irritant that acts primarilyupon the eyes, respiratory tract, and skin; acuteexposure to CS presents itself very much the same asexposures to other RCAs. 50 Exposure almost instantlyresults in irritation, burning, and swelling of theconjunctivae of the eye, accompanied by excessiveFig. 13-5. Insertion of a thermocouple into a hole drilled in aCS canister at Fort Meade, Maryland, to determine dispersaltemperature.Photograph: Courtesy of TA Kluchinsky.447