Lewisite decontamination

One such decontaminant is supertropical bleach (STB). STB is a mixture of chlorinated lime and calcium oxide containing about 30% available chlorine. It can be used either as a dry mix or as a slurry to decontaminate some equipment surfaces and terrain. The dry mix is prepared with two parts bleach to three parts earth by volume. A slurry typically consists of 40 parts STB to 60 parts by weight of water. This material is then sprayed or swabbed on the contaminated surface (see Bleaching agents). STB is an effective decontaminant for mustard, lewisite, and VX. It is less effective against nerve agents other than VX. 

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. 

The rate of action of a chemical agent is the rate at which the body reacts to or is affected by that agent. The rate varies widely, even to those of similar tactical or physiological classification. For example, blister agent HD causes no immediate sensation on the skin. Skin effects usually occur several hours later (some cases result in delays of 10-12 days before symptoms appear). In contrast, lewisite produces an immediate burning sensation on the skin upon contact and blistering in about 13 h. Decontamination immediately (within 4-5 min) will prevent serious blister agent effects. 

If HL (C03-A010) is involved, a BAL (British-anti-Lewisite, dimercaprol) solution or ophthalmic ointment may be beneficial if administered promptly. It may also decrease the severity of skin and eye lesions if applied topically within minutes after decontamination is complete (i.e., within 2-5 minutes postexposure). 

The hazard of a mixture of mustard and Lewisite (HL) on the eyes and skin, or vapor in the eyes or respiratory tract, is immediate. Within an hour, edema of the conjunctivae and lids begin and soon results in eye closure. Any casualty experiences serious pain seconds after contact with HL liquid, but such extreme pain makes the injured person decontaminate at once. Rapid decontamination is the sole manner to avoid severe burns since after a few minutes of contact with a mixture of mustard and Lewisite, the upper layer of skin will die and appear gray, painful erythema will be apparent shortly thereafter, and... 

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. 

Treatment—Patients should be decontaminated immediately prior to treatment using the decontamination method presented in Section 7.3.2. British Anti-Lewisite (BAL) dimercaprol antidote will alleviate some effects. It is available as a solution in oil for intramuscular administration to counteract systemic effects. It is not manufactured currently in the forms of skin and eye ointments.2... 

R. McColm and N.H. Williams, The analysis of Lewisite degradation products in environmental samples and decontamination solutions by liquid chromatography, Presentation at WMD 2003 Conference, Prague, 20-22 May, 2003. 

Uses For decontamination of surfaces exposed to mustard gas or Lewisite. 

Decontamination with soap and water or. 5% solution of bleach and water. British-Anti-Lewisite (BAL) for Lewisite. 

Similar to the mustard agents, exposure prevention is the first line of defense against lewisite. Rapid decontamination is especially relevant to lewisite exposure due to the rapid development of pain (1-2 min) associated with lewisite exposure. Unlike other vesicants, an effective antidote for lewisite toxicity exists in the form of British anti-lewisite (BAL 2,3-dimercaptopropanol) which binds with arsenicals, thereby countering the lewisite-induced damage. Such chelation therapy is associated with notable side effects (e.g. renal effects) and requires carefiil medical management. More effective analogs of BAL have been developed with less significant side effects. 

Immediate eye pain and blepharospasm result from lewisite exposure, followed by conjunctival and lid edema. Severe exposures can produce necrotic injuries of the iris with depigmentation, hypopion, and synechia development. In contrast, very low levels may only involve the conjunctivae (McManus and Huebner, 2005). The eye lesions produced by lewisite are particularly serious blindness will follow contamination of the eye with liquid lewisite unless decontamination is prompt. 

Lewisite Shock Pulmonary injury Blisters Decontamination soap, water, no bleach Antidote BAL-dimercaprol may decrease systemic effects of lewisite Pulmonary management BAL 3-5 mg/kg deep IM q4 h X 4 doses (dose depends on severity of exposure and symptoms) Skin management BAL ointment Eye management BAL ophthalmic ointment... 

Pediatric exposures to vesicants can be quite toxic however, in contrast to nerve agent exposures, HD causes significantly greater morbidity than mortality. While mustard did not cause many deaths in WWI, death from HD exposure is usually due to massive pulmonary damage complicated by infection (bronchopneumonia) and sepsis. Children often show a quicker onset and greater severity of toxicity. Skin and eye toxicity occurs in the form of blisters or irritation that can result in blindness for the most severe cases. Except for lewisite, vesicant exposures must be managed with supportive care and rapid decontamination. 

Like mustard gas, lewbite b almost immediately decompo.scd in the presence of alkalies, such as caustic soda (5 per cent solution) or ammonia, and by active oxydants, such as chloride of lime and the hyiiochloritcK. the rea< tion being greatly accelerated by heat. Hence terrain and material contaminated with lewbite are decontaminated with the same materials as mustard gas. Abo, like mustard, lewisite readily penetrates clothing, leather, rubber, and the tissues of the body, and hence is just ai difficult to protect against. 

To prevent or lessen lewisite damage, early decontamination within minutes after exposure must be instituted. Unlike mustard, lewisite does not cause damage to the hematopoietic organs, but fluid loss from increased capillary permeability necessitates careful attention to fluid balance. 

British antilewisite (BAL) or dimercaprol was developed as an antidote for lewisite. It is used in medicine as a chelating agent for heavy metals. Although BAL can cause toxicity itself, evidence suggests that BAL in oil administered intramuscularly will reduce the systemic effects of lewisite. BAL skin and ophthalmic ointment decrease the severity of skin and eye lesions when applied immediately after early decontamination, but neither of these ointments is currently manufactured. 

Treatment of inorganic arsenic poisoning involves decontamination procedures and use of the antidote BAL (British anti-lewisite compound 2,3-dime-rcaptopropanol). Use of demulcent to coat the gastrointestinal tract and the use of antibiotics is also recommended. Organic arsenic poisoning treatment involves only withdrawal of the feed involved, with recovery occurring in 3-5 days. Severely affected pigs should be culled. 

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. 

Although experts have historically recommended dilute bleach (0.5% sodium hypochlorite) for skin decontamination, with the exception of Lewisite and liquid nerve agent-exposed patients (see following discussion), this recommendation no longer stands for several reasons (7,8) ... 

After sulfur and nitrogen mustards are absorbed and interact with body tissues, they are no longer intact molecules. Therefore, unlike nerve gas victims, the body fluids of decontaminated mustard-exposed patients pose no risk to health care providers or other responders (2). In contrast to the other vesicants, Lewisite does not require a cyclization reaction, so its effects are immediate. Through direct inhibition of thiol-containing enzymes. Lewisite disrupts energy pathways, causing ATP depletion, cell death, and clinical effects (15). 

Lewisite-exposed patients arriving at the hospital within 30-60min of exposure will likely have pain or irritation. Patients without symptoms most likely did not snfifer Lewisite exposure, and they can go home, with instructions to return immediately if they develop symptoms. After decontamination. Lewisite-exposed patients with respiratory symptoms require placement in a critical care unit. Patients withont symptoms, including those sent home, require observation for 18-24h. The sooner after exposure symptoms develop, the more likely they are to progress (24). 

British Anti-Lewisite (BAL), also known as Dimercaprol, is a chelating agent than can reduce systemic effects from Lewisite. BAL works by binding the arsenic group in Lewisite and displacing it from tissue binding sites. If applied topically within minutes, after decontamination, BAL may prevent or reduce the severity of cutaneous and ocular toxicity (8). 

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