Lewisite properties

Hazardous Decomposition Products Reasonably stable however, in presence of moisture, it hydrolyses rapidly, losing its vesicant property. It also hydrolyses in acidic medium to form HC1 and non-volatile (solid) chlorovinylarsenious oxide, which is less vesicant than Lewisite. Hydrolysis in alkaline medium, as in decontamination with alcoholic caustic or carbonate solution or DS2, produces acetylene and trisodium arsenate (Na3 As 04). Therefore, decontaminated solution would contain toxic arsenic. 

Lewisite [dichloro(2-chlorovinyl)arsine] is an organic arsenical known for its vesicant properties (Rosenblatt et al., 1975). It has a molecular weight of 207.32, vapor pressure of 0.58 mm HG at 25°C, a liquid density of 1,89 g/cm at 25°C, freezing point of -18°C, boiling point of 190°C, and is negligibly soluble in water (DA, 1974). The chemical structure of lewisite is shown below. Lewisite may occur as a trans-isomer and as a cis-isomer. In aqueous solutions, the cis-isomer undergoes photoconversion to the trans-isomer (Clark, 1989). hi the presence of moisture, lewisite is rapidly converted to the more stable but highly toxic lewisite oxide (2-chlorovinylarsenous acid) (Cameron et al., 1946). 

Lewisite [L or L-1 dichloro(2-chlorovinyl) arsine] is an arsenical vesicant developed early in the 20th century. Lewisite occurs as cis- and tranx-isomers the typical ratio being 10 90. Several impiuities including 6w(2-chlorovinyl) chloroarsine (L-2) and tnY(2-chlorovinyl)arsine (L-3) are typically present. The chemical and physical properties of the cis- and tranj-isomers are similar. 

The vesicant properties of lewisite result from direct contact with the skin. Signs of dermal toxicity (pain, inflammation) may be experienced within a minute after exposure. Acute lethality is usually the result of pulmonary injury. Ocular exposure may result in corneal necrosis. Due to its lipophilicity, percutaneous absorption of lewisite is rapid and, at a sufficient exposure, may be associated with systemic toxicity characterized by pulmonary edema, diarrhea, agitation, weakness, hypothermia, and hypotension (lOM, 1993). The threshold for severe systemic toxicity in humans following dermal exposure to lewisite has been estimated at lOmg/kg (9.1-13.4 mg/kg) (Sollman, 1957). 

Lewisite remains in the environment for about 24 h and it can react with water to form a solid arsenoxide that also has vesicant properties. Affected areas can be treated with strong alkalis to form less harmful substances. Rescue personnel need to wear protective clothing and masks as the risk for secondary contamination is high. Carcasses should be disposed of properly, either buried deeply (away from... 

Lewisite, a vesicant with HD-Uke properties, causes a similar constellation of signs and symptoms involving the skin, eyes, and airways as well as systemic effects (e.g. increased capillary permeability) after absorption. However, it does not produce immunological suppression like mustard. Another difference is that the management of lewisite toxicity includes an antidote, British Anti-Lewisite (BAL) (Yue/u/.,2003). 

Phenyldichlorarsine, ethyldichloroarsine, and methyl-dichloroarsine have similar properties and toxicities as lewisite. They may be mixed with sulfur mustard similarly as can be done with lewisite and mustard mixtures, and this can confuse the diagnosis between either an arsenical or a mustard injury. 

The clinical effects of lewisite are similar to those of mustard. However, unlike mustard, lewisite liquid or vapor produces irritation and pain upon contact. As with mustard, immediate decontamination will limit lewisite s damage to skin or eyes. A specific antidote for the systemic effects of the agent exists in the form of British Anti-Lewisite (BAL). BAL must be used under medical supervision owing to its own toxic properties. There is no need to have this antidote far forward, and it can be kept in modest quantities because of the minimum threat from lewisite. 

The heavy-metal chelating properties of thiols were taken advantage of in the design of dimercaprol ( British Anti-Lewisite, BAL) as counter poison of the arsenical war gas lewisite (Figure 20.43). Today dimercaprol is used to treat poisoning by compounds of gold, mercury, antimony and arsenic. The toxic nature of the heavy metals is masked and chelate is stable enough to be excreted as such in the urine. 

Lewisite has vesicant properties as well as systemic toxicity. Because lewisite rapidly hydrolyzes to 2-chlorovinyl arsonous acid upon contact with moist surfaces, the toxic properties of lewisite may actually be those of 2-chlorovinyl arsonous acid (Fowler etal., 1991). Percutaneous LD50 values in small mammals range from 5 to 24 mg/kg (Marrs et al., 1996). Lewisite oxide most likely also has vesicant properties (US Army, 1974). The vesicant potency of lewisite degradation products compared to lewisite is... 

Acute toxicity figures for man are not known but a lowest lethal concentration over 30 min of 6 ppm was quoted by Maynard (1989). The LD50 has been measured in a number of species (Table 3), while LCfsoS in a variety of species vary from 500 to 1500 mg min m 3 (Goldman and Dacre, 1989). The efficacy of lewisite, like that of mustard, depends partly upon its vesicant properties but lewisite is also a lethal systemic chemical weapon. About 30 drops (2.6 g), applied to the skin and not washed off or otherwise decontaminated would be expected to produce a fatal outcome in an average man. 

A. General. Due to its physical and chemical properties, lewisite can easily penetrate the skin, where it exerts its vesicant action. A distinctive stinging pain is felt in 10 to 20 seconds after contact with the skin. It can spread through the whole body and act as an arsenical poison. 

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. 

Properties Impure Sulfur Mustard Distilled Sulfur Mustard Phosgene Oxime Lewisite... 

There has been no verified use of Lewisite on a battlefield, although Japan may have used it against China between 1937 and 1944.93 Currently, this vesicant is probably in the chemical warfare stockpile of several countries. Lewisite is sometimes mixed with mustard to lower the freezing point of mustard Russia has this mixture." Properties... 

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