Nerve agents thickened

They are generally divided into the G-agents, which in the unmodified state are volatile, and the V-agents, which tend to be more persistent. Even G-agents are capable of being thickened with various substances to increase the persistence and penetration of the intact skin. The principal nerve agents are Tabun (GA), Sarin (GB), Soman (GD), and VX. 

There are seven sites in the United States where U.S. Unitary Chemical Stockpile exists. Below they are listed by chemical weapon as follows GB, sarin H, mustard HD, mustard HT, mustard VX, persistent nerve agent GA, tabun L, lewisite TGA, thickened tabun TGB, thickened sarin. 

Nerve agent intoxication requires rapid decontamination to prevent further absorption by the patient and to prevent exposure to others, ventilation when necessary, administration of antidotes, as well as supportive therapy. Skin decontamination is not necessary with exposure to vapor alone, but clothing should be removed to get rid of any trapped vapor. With nerve agents, there can be high airway resistance due to bronchoconstric-tion and secretions, and initial ventilation is often difficult. The restriction will decrease with atropine administration. Copious secretions which maybe thickened by atropine also impede ventilatory actions and will require frequent suctioning. For inhalation exposure to nerve agents, ventilation support is essential. 

All unthickened "V" series Nerve Agents are classified as persistent. Evaporation rates ranging from near that of light machine oil up to that of motor oil. Thickened agents last significantly longer. 

In another study, clipped rabbits were exposed to sulfur mustard, lewisite (L), thickened soman, and VX and were decontaminated between 30 s and 5 min postexposure. Eor the vesicants (sulfur mustard and L), lesion areas were compared. Decontaminating for 1 min resulted in the lesion areas being reduced 21-fold for sulfur mustard and 22-fold for L, relative to no decontamination. For the nerve agents (soman and VX), the inhibition of blood acetylcholinesterase (AChE) was used as a marker. Using a 2 min decontamination time, the dose of nerve agent required to produce 50% inhibition of AChE was increased 1.8-fold for thickened soman and 18-fold for VX (Hobson et al., 1993). 

Bulk agents included mustard (bis-2-chloroethyl sulfide, 12 tonnes), lewisite (2-chlorovinyl-dichloro arsine, 2.5 tonnes) and nerve agents in the G- and V-classes (0.3 tonne). The scrap (400 tonnes) consisted mainly of several thousand empty, mustard-contaminated 210 drums and ordnance casings stored in open pits. All of the lewisite and some of the mustard and nerve agents were stored in 1 ton containers. Nerve agents were also stored in non-explosive ordnance, primarily 105 and 155 mm artillery shells. Mustard which had aged or had been thickened with polymers was also contained in non-explosive ordnance. The waste previously had been sorted by type, collected and stored at four remote, protected sites on the EPG. 

AU four nerve agents are toxic by absorption through the skin. VX is particularly dangerous in this way as it is a viscous liquid, splashes of which are not easily removed from the skin. Indeed, VX has been mixed with thickening agents to provide a mixtiire which effectively cannot be washed or wiped off. Also, Soman can... 

Nerve agents are organophosphonate compounds they contain phosphorus double-bonded to an oxygen atom and single-bonded to a carbon atom. GB is O-isopropyl methylphosphonofluoridate. VX is 0-ethyl-S[2-(diisopropyl amino) ethyl]-methylphosphonothiolate. Bis(2-chloroethyl) sulfide is the proper chemical name for mustard agent HD and HT (a thickened form). Mustard gas, sulfur mustard, and yperite have also been used for this agent. The term mustard gas is often used, but the chemical is a liquid at ambient temperature. 

Mackay and coworkers [33,34] and Moss and coworkers [35] showed that reactions of nucleophiles with phosphorus(V) esters, which are models for nerve agents, can be carried out effectively in microemulsions. The active agents often contain polymeric thickeners, and the solubilizing power of microemulsions is of crucial importance. Typically cationic surfactants are used with alcohols or alMpyrollidinones as cosurfactants. lodosobenzoate ions (2) are nucleophilic turnover catalysts toward fluorophosphonate nerve agents and phosphate esters, and Moss and coworkers used amphiphilic iodosobenzoate ions extensively in this work [36] (see Scheme 2). 

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