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

Medical Aspects of Chemical WarfareMcNamara and associates 27 summarized six experimentsto determine the incapacitating concentration ofCS. The experiments varied in concentrations (5–422mg/m 3 ), method of dispersal, and exposure time(30–300 seconds). The incapacitating effects were thesame at that noted by Gutentag and associates. Theincapacitating concentration for 50% of the populationwas determined to be somewhere between 0.1 and 10mg/m 3 , depending upon the motivation of the exposedpopulation. There was no difference in tolerance timesamong dispersal methods or for men over age 50. Thisstudy also concluded that incapacitation time was reducedwith increased temperature and humidity. 27Beswick and associates 35 exposed 35 men to 1-µmparticles of CS dispersed in a 100-m 3 chamber by theignition of 1-g CS pellets. The concentration variedfrom 0.43 to 2.3 mg/m 3 over a period of 60 minutes.Symptoms of exposure included nasal pain and discharge,rhinorrhea, throat irritation, tightness andburning of the chest, and difficulty breathing. Subjectsdeveloped tolerance to the compound and were ableto remain in the chamber for 60 minutes, despite the4-fold increase in concentration. Postexposure measurementsrevealed no differences in peak flow, tidalvolume, or vital capacities from those made beforethe exposure. 35Cole and associates 68 exposed several male volunteersto concentrations of 0.16 to 4.4 mg/m 3 in anexposure chamber. Ventilation minute volume wasobserved to decrease an average of 6% in the exposedpopulation. 68Based upon the data presented, a variety of healthrelatedvalues have been calculated. The NIOSHrecommended exposure limit ceiling value is 0.4 mg/m 3 . This ceiling value should not be exceeded at anytime. The OSHA permissible exposure limit is 0.4 mg/m 3 . This is the concentration of CS, averaged over an8-hour workday, to which most workers can be exposedwithout adverse effect. The value consideredimmediately dangerous to life and health (IDLH) is2 mg/m 3 . 69In a final report to the deputy attorney general,Heinrich 70 stated that CS can be detected by the humannose at an odor threshold value of 0.004 mg/m 3 .Blain 71 stated that concentrations of 0.004 mg/m 3 aredetectable by the human eye and that concentrationsof 0.023 mg/m 3 are detectable in the airways. He alsostated that the ICt 50, or the concentration that is intolerableto 50% of the exposed population for 1 minute, is3.6 mg/m 3 . This value is consistent with the work ofPunte, Gutentag, and McNamara. 72,73 A summary reportproduced by the Directorate of Medical Researchat Edgewood Arsenal, Maryland, cites the LCt 50formolten CS as 52,000 mg•min/m 3 and 61,000 mg•min/m 3 by thermal grenade. The same report cites the ICt 50as ranging from 0.1 to 10 mg•min/m 3 . 53Dermatological effects. CS exposure can result in amultitude of cutaneous reactions, such as allergic contactdermatitis, rashes, blisters, and burns. Exposuremanifests itself as a delayed (several minutes) stingingsensation that is less remarkable than the reaction ofthe eyes and nose. The severity of the reaction dependsupon several variables including (but not limited to)the method of dispersal, CS concentration, temperature,and humidity. 72Gutentag and associates 51 conducted a series ofpatch tests on several volunteers, using CS protectedfrom the air, CS in a porous gauze covering, a 10%CS solution in methylene dichloride, and a 20% CSsolution in methylene dichloride. The porous gauzecovering produced the greatest skin effect, causing fourof four volunteers to develop vesicles surrounded byerythema. The 10% CS solution caused no skin reactionin three of three volunteers. The researchers alsoexposed subjects to wind-dispersed CS via CS-acetonespray (3 µm), CS-methylene dichloride spray (1 µm),and an M18 grenade (0.5 µm). Subjects reported burningon exposed areas of the skin that increased withthe presence of moisture. The burning sensation lastedfor several hours and recurred when the affected areawas moistened. Heavy exposures produced vesiculationand reddening that resembled a second-degreeburn. 51Hellreich and associates 74 exposed the arms ofvolunteers to an average concentration of 300 mg/m 3 for 15 to 60 minutes via thermal grenade. Within5 minutes of exposure, subjects experienced a burningsensation of the skin; concentration multipliedby time (Ct) exposures of 4,440 and 9,480 mg•min/m 3 produced immediate reddening of the skin. Uponremoval from the exposure area, subjects washed theirarms and found the burning sensation to increase.Within 30 minutes of removal from the environment,all symptoms of exposure resolved. 74 In a follow-onstudy, Hellreich and associates 75 used patches to testthe dermal effects of CS on the arms of volunteers atfour temperature conditions. The patches were takenoff at specified exposure times to give exposures at37°C with 98% relative humidity (RH), 14°C with41% RH, 20°C with 95% RH, and 22°C with 72% RH.Higher temperatures and humidity resulted in a lowerCt required to produce skin effects. 75Rengstorff 76 documented CS exposures in firefightersin Washington, DC, during the 1968 riots, when lawenforcement agents used CS to disperse rioters frombuildings. Some structures were set ablaze duringthe rioting; as firemen entered the building, the heat,movement, and force of the water from their hoses450