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

Decontamination of Chemical CasualtiesabFig. 16-1. (a) Treatment barracks for gas cases. Evacuation Hospital #2 [ca World War I]. (b) Mobile degassing unit #1. Tours,France. November 21, 1918.Photographs: Courtesy of the National Museum of Health & Medicine, Armed Forces Institute of Pathology (a: Reeve 1179;b: Reeve 12196).patient decontamination methods since World War I,the beginning of modern chemical warfare (Figure16-1). Many substances have been evaluated for theirusefulness in skin decontamination. The most commonproblems with potential decontaminants are irritationof the skin, toxicity, ineffectiveness, or high cost. Anideal decontaminant would rapidly and completelyremove or detoxify all known chemical (as well asbiological and radiological) warfare agents from bothskin and equipment (Exhibit 16-2). Decontaminantsused for equipment have often been considered forhuman skin but are found unsuitable because theycause chemical burns. 18Recent research has explored the use of water, soapand water, polyethylene glycol and polyvinylpyrrolidone19 ; polyethylene glycol (PEG 300, PEG 400) andglycerol or industrial methylated spirit mixtures 20 ;hydrogen peroxide foam mixtures (Sandia foam, ModecDecon Formula) 21 ; immobilized enzymes (Gordonsponge) 22–25 ; cyclodextrines 26 ; ozones (L-Gel) 27 ; organophosphorusacid anhydrolases 28 ; phosphotriesterases 29 ;chloroperoxidases 30 ; a mixture of bovine hemoglobin,gelatin, and poi 31 ; blends of catitonic and anionictensides 32 ; hydroperoxides and hydroperoxycarbonateanions, dichloroisocyanurate, and oxidants suchas sodium hypochlorite and calcium hypochlorite 33 ;polyglycol and corn oil 34 ; and technology such as theuse of atmospheric pressure plasma jets 35 and postexposurecooling. 36Currently recommended decontamination materialsfor US service members that are safe for human skin includesoap and water (hydrolysis is probably the mosteconomical choice if water is readily available in amplequantities); dry decontaminants (eg, fuller’s earth,M291 skin decontamination kit [SDK]); packaged liquiddecontaminants (eg, the Canadian-manufacturedReactive Skin Decontamination Lotion [RSDL; E-Z-EMCanada Inc, Anjou, Quebec, Canada]); and chemicaldecontaminants that create an oxidative reaction withthe agent (eg, dilute 0.5% hypochlorite solution [dilutebleach]). Table 16-2 gives the suggested applicationsfor the various decontamination materials.HD and the persistent nerve agent VX contain sulfuratoms that are readily subject to oxidation and/or dehydrochlorination reactions. VX and the othernerve agents (GD, GA [tabun], GB [sarin], and GF[cyclosarin]) contain phosphorus groups that undergoalkaline hydrolysis. HD can also be neutralized byhydrolysis or other nucleophilic substitution, but therate is generally slow. Therefore, most chemical decontaminantsare designed to neutralize CWAs by eitheroxidative chlorination or hydrolysis. 1Soap and Water: HydrolysisMany classes of CWA, including HD, V agents, andG agents, can be detoxified by reaction with nucleophiles(water is the nucleophile). Chemical hydrolysisreactions are either acid or alkaline. Acid hydrolysisis of negligible importance for agent decontaminationbecause the hydrolysis rate of most chemical agents isslow, and adequate acid catalysis is rarely observed. 8Alkaline hydrolysis is initiated by the nucleophilicattack of the hydroxide ion on the phosphorus atoms533