Arsenical vesicants

The majority of these materials are first generation chemical warfare agents employed in World War I. They are moderately difficult to synthesize and can be difficult to disperse effectively. For information on some of the chemicals used to manufacture arsenic vesicants, see the Component section (C04-C) following information on the individual agents. 

In addition to the agents detailed in this handbook, there are other arsenic vesicants that were employed during World War I on a limited basis. However, there is little or no published information concerning the physical, chemical, or toxicological properties of these additional agents. 

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. 

Arsenic vesicants cause instantaneous irritation of the eyes, nose, throat, and skin, which provides warning of their presence. Extended exposures cause violent coughing, sneezing, and regurgitation. The odor of arsenic vesicants varies with the individual compound and ranges from odorless to fruity to flowery. Odors may not be discernable due to irritation. 

Although sublethal doses of some arsenic vesicants are rapidly detoxified by the body, many agents are not detoxified and exposures are cumulative. 

Arsenic vesicants produce immediate pain. Tissue damage occurs within minutes of exposure but clinical effects may not appear for up to 24 hours. Some agents are rapidly absorbed through the skin. Extensive skin contamination may cause systemic damage to the liver, kidneys, nervous system, red blood cells, and the brain. 

Arsenic vesicants have been thickened with various substances to enhance deployment, increase their persistency, and increase the risk of percutaneous exposure. Thickeners include polyalkyl methacrylates (methyl, ethyl, butyl, isobutyl), polyfvinyl acetate), polystyrene, plexiglas, alloprene, polychlorinated isoprene, nitrocellulose, as well as bleached montan and lignite waxes. Military thickener K125 is a mixture of methyl, ethyl, and butyl polymethacrylates. When thickened, agents become sticky with a consistency similar to honey. Typically, not enough thickener is added to affect either the color or odor of the agent. 

Arsenic vesicants are stable when pure and kept dry. Stabilizers are not required. Agents can be stored in glass or steel containers, although they may attack steel at elevated temperature or if moisture is present. Arsenic vesicants corrode aluminum and brass, and will attack some rubbers and plastics. 

For military purposes, unmodified arsenic vesicants are classified as persistent. However, agent vapors rapidly react with high humidity to lose most of their vesicant properties. Limited solubility slows the hydrolysis of liquid agents. Some hydrolysis products are highly toxic and extremely persistent (see Section 4.4.5). Evaporation rates range from near that of water down to that of light machine oil. 

Meat and milk from animals affected by arsenic vesicants should be destroyed. 

Heat from a fire will increase the amount of agent vapor in the area. A significant amount of the agent could be volatilized and escape into the surrounding environment before it is consumed by the fire. Actions taken to extinguish the fire can also spread the agent. Combustion or hydrolysis of arsenic vesicants will produce volatile, toxic decomposition products (see Section 4.4.5). 

Arsenic vesicants produce hydrogen chloride (HC1) or hydrogen bromide (HBr), and arsenous oxides or arsenic salts when hydrolyzed. Some arsenous oxide decomposition products are toxic and may also have vesicant properties. Some agents may produce acetylene at higher pHs. 

Structural firefighters protective clothing is recommended for fire situations only it is not effective in spill situations or release events and should never be used as the primary chemical protective garment to enter an area contaminated with arsenic vesicants. 

Immediately dangerous to life or health (IDLH) levels are the ceiling limit for respirators other than SCBAs. However, IDLH levels have not been established for arsenical vesicants. Therefore, any potential exposure to these agents should be regarded with extreme caution and the use of SCBAs for respiratory protection should be considered. 

Use only chemical protective clothing that has undergone material and construction performance testing against arsenic vesicant agents. Reported permeation rates may be affected by solvents, components, or impurities in munition grade or modified agents. 

Because of the extreme dermal hazard posed by arsenic vesicants, responders should wear a Level A protective ensemble whenever there is a potential for exposure to any liquid agent, or to an elevated or unknown concentration of agent vapor. 

Arsenic vesicants are rapidly hydrolyzed in water but a lack of solubility may slow the rate of reaction. Arsenic decomposition products are stable and some of them have toxic and/or vesicant properties that nearly equal the original agent. 

Steam is an effective method of destroying arsenic vesicants. However, care must be taken to limit the spread of the agent and to guard against production of the toxic and potentially vesicating hydrolysis products (see Section 4.4.5). 

Reactive oximes and their salts, such as potassium 2,3-butanedione monoximate found in commercially available Reactive Skin Decontaminant Lotion (RSDL), are extremely effective at rapidly detoxifying arsenic vesicants. 

A case in which an arsenic vesicant is detected in biologic samples. The case can be confirmed if laboratory testing is not performed because either a predominant amount of clinical and nonspecific laboratory evidence is present or an absolute certainty of the etiology of the agent is known. 

Exposure of the skin to arsenic vesicants produces an immediate burning sensation. Reddening of the skin (erythema) may appear in as short a time as 5 minutes although full progression to blisters may not develop for up to 18 hours. Although blisters tend to be deeper and more painful than produced by sulfur vesicants (Chapter 3), they heal more readily. 

BAL is the standard treatment for poisoning by arsenic compounds and will alleviate some effects from exposure to arsenic vesicants. 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). Additional chelating agents for the treatment of systemic arsenic toxicity include meso-2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercapto-l-propanesulfonic acid (DMPS). 

Standard burials are acceptable when contamination levels are low enough to allow bodies to be handled without wearing additional protective equipment. Cremation may be required if remains cannot be completely decontaminated. Although arsenic vesicant agents are destroyed at the operating temperature of a commercial crematorium (i.e., above 1000°F), the initial heating phase may volatilize some of the agents and allow vapors to escape. Additionally, combustion will produce toxic and potentially volatile arsenic oxides. 

This material is a general precursor for arsenical vesicants and many vomiting/sternatory agents (Chapter 14). 

During World War I, pulmonary agents were sometimes mixed with various metal chlorides to produce a visible cloud. Agents were also sometimes mixed with arsenical vesicants (Agent Index C04) to increase their lethality. 

Guides for Emergency Response Chemical Agent or Weapon Arsenical Vesicants including Ethyldichloroarsine (ED), Methyldichloroarsine (MD), Phenyldichloroarsine (PD)... 

Emergency Response Chemical Agent or Weapon Arsenical Vesicants... 

Caution Some serious burns from arsenical vesicants can cause shock and systemic poisoning and are life-threatening even when the victim survives the acute effects the... 

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