Arsenic vesicants persistency

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. 

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. 

Arsenical Vesicants are colorless to brown liquids. These agents generally have fruity or flowery odors although pure materials may be odorless. Agents can be thickened with various substances to increase their persistency and dermal hazard. When thickened, agents have a consistency similar to honey. 

Arsenical Vesicants are persistent agents. However, agent vapors rapidly react with high humidity to lose most of their vesicant properties. Limited solubility slows the hydrolysis of liquid agents. 

Vapors from Arsenical Vesicants have a density greater than air and tend to collect in low places. Liquids are persistent but are rapidly decomposed by water. These agents are absorbed into porous material, including painted surfaces, and these materials could continue to re-release vapor after exposure has ceased. Agent vapor is rapidly decomposed by moisture in the air. The rate of hydrolysis of liquid agents is limited by their low solubility in water. The liquid density of these agents is greater than that of water. 

Sulfur/Arsenical Vesicants are persistent agents and, under proper conditions, remain hazardous in soils for several years. Thickened agents last significantly longer. 

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... 

Properties Oily liquid having a geranium odor. Sp. gr. 1,88. B. P. 190°. A persistent, violent vesicant, highly toxic (arsenical poison). Can be used in liquid or vapor form, in other words, in shells, bombs, or as a spray. Decomposed by hydrolysis. Alcoholic sodium hydroxide spray used as means of destroying the product in the field, after first washing down with water. 

The most common agents in modern arsenals are vesicants and nerve agents. Cyanides and pulmonary toxicants are thought to be represented in some stockpiles, but are typically less toxic and more difficult to employ because of their physical characteristics. Some cyanides and pulmonary toxicants have specific characteristics that make them appropriate for military use, such as rapid rate of action, very low persistency, and the ability to penetrate or damage protective equipment. 

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