A blister agent (or vesicant) is a chemical compound that causes severe skin, eye and mucosal pain and irritation in the form of severe

chemical burns A chemical burn occurs when living tissue is exposed to a corrosive substance (such as a strong acid, base or oxidizer) or a cytotoxic agent (such as mustard gas, lewisite or arsine). Chemical burns follow standard burn classification and may ca ...

resulting in fluid filled blisters. Named for their ability to cause vesication, blister agent refers in common parlance to those agents which are developed for, or have been in the past utilized as

chemical weapons A chemical weapon (CW) is a specialized munition that uses chemicals formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), this can be any chemical compound intended as ...

, though some naturally occurring substances such as

cantharidin Cantharidin is an odorless, colorless fatty substance of the terpenoid class, which is secreted by many species of blister beetles. Its main current use in pharmacology is treating molluscum contagiosum and warts topically. It is a burn agent ...

fall under the same terminology.Cantharidin and Meloids: a review of classical history, biosynthesis, and function
Exposure to blister agents is widely incapacitating, but often precipitates a delayed effect, with symptoms developing one to twenty four hours following the initial contact with the agent. Treatment for acute exposure is largely supportive, with the exception of

Lewisite Lewisite (L) (A-243) is an organoarsenic compound. It was once manufactured in the United States, Japan, Germany and the Soviet Union for use as a Chemical warfare, chemical weapon, acting as a vesicant (blister agent) and lung irritant. Although ...

, for which an antidote is available. Overall lethality as a direct result of exposure is low, but increases with dose. Despite low overall lethality, blister agent exposure requires extensive supportive treatment, and can cause significant strain on medical systems. In some cases, blister agents have limited medical uses including for purposes of wart removal.

Blister agents used in warfare

Blister agents relevant to warfare are generally divided into three categories: * Mustards - A family of related agents whose odor is similar to mustard plants,

garlic Garlic (''Allium sativum'') is a species of bulbous flowering plants in the genus '' Allium''. Its close relatives include the onion, shallot, leek, chives, Welsh onion, and Chinese onion. Garlic is native to central and south Asia, str ...

, or

horseradish Horseradish (''Armoracia rusticana'', syn. ''Cochlearia armoracia'') is a perennial plant of the family Brassicaceae (which also includes Mustard plant, mustard, wasabi, broccoli, cabbage, and radish). It is a root vegetable, cultivated and us ...

, giving them their name. This family includes two primary subtypes: **

Sulfur mustards Mustard gas or sulfur mustard are names commonly used for the organosulfur chemical compound bis(2-chloroethyl) sulfide, which has the chemical structure S(CH2CH2Cl)2, as well as other species. In the wider sense, compounds with the substituen ...

– A subfamily of

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

-based agents, including what was referred to as mustard gas during World War I. **

Nitrogen mustard Nitrogen mustards (NMs) are cytotoxic organic compounds with the bis(2-chloroethyl)amino ((ClC2H4)2NR) functional group. Although originally produced as chemical warfare agents, they were the first chemotherapeutic agents for treatment of canc ...

s – A subfamily of agents similar to the sulfur mustards, but based on

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

instead of sulfur, of which three varieties exist which are significant to warfare. * Organoarsenics - A family of agents including

ethyldichloroarsine Ethyldichloroarsine, sometimes abbreviated as "ED" and "CY" and also known as ethyl Dick, is an organoarsenic compound with the formula CH3CH2AsCl2. This colourless volatile liquid is a highly toxic obsolete vesicant or blister agent that was use ...

(ED),

methyldichloroarsine Methyldichloroarsine, sometimes abbreviated "MD" and also known as methyl Dick, is an organoarsenic compound with the formula CH3AsCl2. This colourless volatile liquid is a highly toxic vesicant that has been used in chemical warfare. History G ...

(MD) and

phenyldichloroarsine Phenyldichloroarsine, also known by its wartime name phenyl Dick and its NATO abbreviation PD, is an organic arsenical vesicant and vomiting agent developed by Germany and France for use as a chemical warfare agent during World War I. The agent i ...

(PD). *

– An early blister agent that was developed, but not used, during

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

. It was effectively rendered obsolete with the development of

dimercaprol Dimercaprol, also called British anti-Lewisite (BAL), is a medication used to treat acute poisoning by arsenic, mercury, gold, and lead. It may also be used for antimony, thallium, or bismuth poisoning, although the evidence for those uses is n ...

in the 1940s. Some sources erroneously report

phosgene oxime Phosgene oxime, or CX, is an organic compound with the formula . It is a potent chemical weapon, specifically a nettle agent. The compound itself is a colorless solid, but impure samples are often yellowish liquids. It has a strong, disagreeable ...

, a

nettle agent Nettle agents (named after stinging nettles) or urticants are a variety of chemical warfare agents that produce corrosive skin and tissue injury upon contact, resulting in erythema, urticaria, intense itching, and a hive-like rash. Most nettle ...

as a blister agent. Because it causes

urticaria Hives, also known as urticaria, is a kind of skin rash with red or flesh-colored, raised, itchy bumps. Hives may burn or sting. The patches of rash may appear on different body parts, with variable duration from minutes to days, and typically ...

, not vesication, the grouping is not consistent with the accepted categorization of the blister agents.

Effects

Exposure to a weaponized blister agent can cause a number of life-threatening symptoms, including: * Severe skin, eye and mucosal pain and irritation * Skin

erythema Erythema (, ) is redness of the skin or mucous membranes, caused by hyperemia (increased blood flow) in superficial capillaries. It occurs with any skin injury, infection, or inflammation. Examples of erythema not associated with pathology inc ...

with large fluid

blister A blister is a small pocket of body fluid (lymph, serum, plasma, blood, or pus) within the upper layers of the skin, usually caused by forceful rubbing (friction), burning, freezing, chemical exposure or infection. Most blisters are filled ...

s that heal slowly and may become infected *

Tearing Tearing is the act of breaking apart a material by force, without the aid of a cutting tool. A tear in a piece of paper, fabric, or some other similar object may be the result of the intentional effort with one's bare hands, or be accidental. ...

conjunctivitis Conjunctivitis, also known as pink eye or Madras eye, is inflammation of the conjunctiva, the thin, clear layer that covers the white surface of the eye and the inner eyelid. It makes the eye appear pink or reddish. Pain, burning, scratchiness ...

cornea The cornea is the transparency (optics), transparent front part of the eyeball which covers the Iris (anatomy), iris, pupil, and Anterior chamber of eyeball, anterior chamber. Along with the anterior chamber and Lens (anatomy), lens, the cornea ...

l damage * Mild

respiratory distress Shortness of breath (SOB), known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing discomfort that c ...

to marked airway damage All blister agents currently known are denser than air, and are readily absorbed through the eyes, lungs, and skin. Exposure to blister agents may precipitate a wide variety of long term effects due primarily to their general statuses as

carcinogens A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...

, and their abilities to cause permenant cellular damage.

References

External links

Medterms.com

Medical Aspects of Biological and Chemical Warfare, Chapter 7: Vesicants
{{Chemical warfare