O-chlorobenzylidene malononitrile (CS riot control agent) exposure in a U.S. Army basic combat training cohort.

All U.S. Army soldiers participate in mask confidence training during initial military training and periodically throughout their careers. Training is conducted by dispersing the riot control agent, o-chlorobenzylidene malononitrile (CS), in a relatively air-tight structure where soldiers enter and conduct a series of exercises that culminate with mask removal. The study described here quantified CS concentrations experienced by 6,723 trainees and seven chamber operators during U.S. Army basic combat training at Fort Jackson, South Carolina, from August 1 to September 25, 2012. All 6,723 trainees were potentially exposed to CS concentrations exceeding the American Conference of Governmental Industrial Hygienists threshold limit value-ceiling (TLV-C) (0.39 mg/m3), 6,589 of which were potentially exposed to concentrations exceeding the value deemed immediately dangerous to life and health (IDLH) (2.0 mg/m3) by the National Institute for Occupational Safety and Health. All chamber operators were exposed to concentrations exceeding both the TLV-C and the IDLH.