o-Chlorobenzylidene Malononitrile (CS Riot Control Agent) Associated Acute Respiratory Illnesses in a US Army Basic Combat Training Cohort

Acute respiratory illnesses (ARIs) are among the leading causes for hospital visits in U.S. military training populations and historically peak during U.S. Army Basic Combat Training (B CT) following mandatory exposure to the riot control agent o-chlorobenzylidene malononitrile (CS). This observational prospective cohort studied the association between CS exposures and ART-related health outcomes in 6,723 U.S. Army recruits attending BCT at Fort Jackson, South Carolina from August 1 to September 25, 2012 by capturing and linking the incidence of ART before and after the mask confidence chamber to CS exposure data. Recruits had a significantly higher risk (risk ratio = 2.44; 95% confidence interval =1.74, 3.43) of being diagnosed with ART following exposure to CS compared to the period of training preceding exposure, and incidence of ART after CS exposure was dependent on the CS exposure concentration (p = 0.03). There was a significant pre-/postexposure ART difference across all CS concentration levels (p < 0.01), however, no significant differences were detected among these rate ratios (p = 0.72). As CS exposure is positively associated with ART health outcomes in this population, interventions designed to reduce respiratory exposures could result in decreased hospital burden and lost training time in the U.S. Army BCT population.