Solutions RCAs dispersed

RCAs are solids with low vapor pressures. They can be dispersed as fine powders foams, as coherent jets or streams of solutions from small or large spray cans, large spray tanks, or larger weapons and as aerosols or smokes by pyrotechnic generation (Table 2). 

Whether dispersed as aerosol, smoke or in solution, RC As will contaminate the skin and eye and may cause local acute inflammation at these sites. It is therefore a necessity to be aware if contact with skin and eye will have a local tissue injuring potential, and how formulation may influence the outcome. Supplemental to standard eye irritation tests, it is of practical value to undertake studies on the influence of RCAs on corneal thickness by pachymetry and on intraocular pressure (IOP) by tonometry (Ballantyne, 1999b Ballantyne et al., 1977a). 

PCSI materials used in the context of atmospherically dispersed materials are sometimes classified as stemutators if their main action is on the upper respiratory tract, and lacrimators if the principal action is on the eye. For most currently used PCSIs, this is not a useful classification descriptor, since both effects are frequently present. Thus, exposure to an airborne PCSI RCA will cause effects in skin, eye and respiratory tract. When dispersed in solution, the effects are generally limited to the area of contact, and the reflexes elicited are a function of the afferent nerve involvement. In general, PCSI effects appear within seconds of contact, and subside within 10-60 min, depending on exposure concentration and site affected. 

The above findings confirm that exposure to PSCI RCAs by airborne dispersion or by contamination in solution produce abrupt and marked increases in SBP and DBP, with resolution within about 0.5 h of the start of exposure. The magnitude and duration of the changes can be tolerated without significant medical hazards in healthy individuals. However, as with other stressful situations, some susceptible individuals may be at increased risk from the induced transient hypertensive episode this will include those with essential hypertension, established myocardial infarction and coronary artery disease, cardiac arrhythmias and arterial aneurysms (Ballantyne, 1977a, 1987 Ballantyne and Salem, 2004). 

RCAs are peripheral chemosensory irritants that target the eyes, airways and/or skin. The 1997 CWC defines them as Any chemical not listed in a Schedule, which can produce rapidly in humans sensory irritation or disabling physical effects which disappear within a short time following termination of exposure . Use for riot control purposes is permitted under the CWC, but not for military harassment, and stocks of RCAs must be declared. Most of the major RCAs [CN, CS and dibenz[/),/]-l,4-oxazepine (CR) Scheme 1.8] are low volatility solids and, unless they are used in solution in a spray, they need to be aerosolised for efficient use, for example using pyrotechnic munitions or dispersed as micronised powders. 

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