Arsenicals, Lewisite

Blister agents Also known as vesicants, these are chemical weapon compounds that cause severe blistering of the skin, as well as damage to the eyes, mucous membranes, respiratory tract and internal organs. This class of chemical weapon agent includes the arsenicals/Lewisites (L), phosgene oxime (CX), and sulfur mustards (HD, HN). 

Vesicants, such as sulfur mustard (HD) and the arsenical Lewisite (L), cause irritation and vesication of the skin and mucous membranes, notably of the lungs. Mustard exposure to the skin is insidious, causing no immediate discernible effects to the skin for several hours blistering occurs 12 to 24 hours after exposure.25 Although mustard causes few deaths, its vesicating properties are incapacitating, and casualties require 1 to 4 months of hospitalization. Lewisite blisters heal within several weeks. 

Because it contains arsenic, lewisite has some effects that are similar to arsenic poisoning, including stomach ailments and low blood pressure. 

The situation for contaminants, containing arsenic (lewisite, adamsite, and clarke-1) is distinct from the above one, but is not any better. The products of their hydrolysis are poorly water-soluble, but, what is more important, they are highly toxic. Therefore, if such contaminants get into a sea medium from the places of their burial, large areas of the seabed will be poisoned by highly toxic substances, in particular, by inorganic compounds of trivalent arsenic. Life will be impossible in these regions. 

The workshop revealed that analytical methods do exist to effectively support the destruction of chemical munitions. This is not to say that faster, more sensitive methods are not needed, especially in the area of organo-arsenicals (Lewisites). However, the papers presented at this workshop have made an excellent baseline for further advance in the analytical chemistry associated with the destruction of chemical weapons... 

It hydrolyses in acidic medium to form HC1 and nonvolatile (solid) chlorovinylarsenious oxide, which is a less potent vesicant than Lewisite L-2. Hydrolysis in alkaline medium, as in decontamination with alcoholic caustic or carbonate solution, produces acetylene and trisodium arsenate (Na3AS04). Therefore, decontaminated solution would contain toxic arsenic. 

New substances (hydrolysis products) form when an agent or compound reacts with water. In certain cases hydrolysis does not completely destroy the toxicity of an agent or compound. The resulting hydrolysis products may also be toxic. Examples include lewisite and other agents containing arsenic. 

Blister agents, which cause burns on the skin such as sulfur mustard gas, l,l -thiobis[2-chloroethane] (HD), and lewisite, (2-chloroethenyl) arsenous dichloride (L). 

Agent vapors of both series cause eye irritation. However, there is no significant difference in the concentration that will irritate the eyes and the one that will produce eye injury. Although impacts from exposure to vesicants occur almost at once, contact with vapors or the liquid agent neither irritates the skin nor produces visible dermal injuries until after a substantial latency period. In contrast, HL (C03-A010), sulfur mustard mixed with lewisite, produces immediate pain due to the arsenic mustard component. 

Toward the end of World War I, lewisite (C04-A002) was developed, produced, and weaponized but never used. Despite this, it has supplanted all other agents as the arsenic vesicant of choice and is the only one that was stockpiled in modern arsenals. 

Dimercaprol (British Anti-Lewisite or BAL) is a colorless, viscous oily compound with an offensive odor used in treating arsenic, mercury, and gold poisoning. It displaces the arsenic bound to enzymes. The enzymes are reactivated and can resume their normal biological activity. When given by injection, BAL can lead to alarming reactions that seem to pass in a few hours. 

Lewisite is generally considered a suspect carcinogen because of its arsenic content. 

Chronic Exposure Lewisite can cause sensitization and chronic lung impairment. Also, by comparison to agent mustard and arsenical compounds, it can be considered as a suspected human carcinogen. 

An arsenical is a blister agent based around a chloroarsine (AsC13) molecule in which one of the chlorine atoms is replaced by an organic radical. Arsenicals include methyldichloroarsine (MD), phenyldichloroarsine (PD), ethyldichloroarsine (ED), and lewisite (L). Personnel exposed to any of these agents should be decontaminated immediately and given medical attention. 

The largest of the branch laboratories was established at Catholic University in Washington, D.C. Its staff of about 75 carried out research on arsenic compounds and subsequently developed one of the new war gases produced by the United States during World War I, Lewisite C26). 

Lewisite (L, 2Cchloroviny Idichloroarsine, 2-chlorovinyl arsonous dichloride) Vesicant — blister agent with Arsenic 30-50 mg/Kg (skin) Highly persistent because of Arsenic in formulation... 

Dimercaprol (BAL, British Anti-Lewisite) was developed in World War 11 as an antidote against vesicant organic arsenicals (B). It is able to chelate various metal ions. Dimercaprol forms a liquid, rapidly decomposing substance that is given intramuscularly in an oily vehicle. A related compound, both in terms of structure and activity, is di-mercaptopropanesulfonic acid, whose sodium salt is suitable for oral administration. Shivering, fever, and skin reactions are potential adverse effects. 

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