A blood agent is a toxic chemical agent that affects the body by being absorbed into the blood. Blood agents are fast-acting, potentially lethal poisons that typically manifest at room temperature as volatile colorless gases with a faint odor. They are either cyanide- or

arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...

-based.

Exposure

Blood agents work through inhalation or ingestion. As chemical weapons, blood agents are typically disseminated as

aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be generated from natural or Human impact on the environment, human causes. The term ''aerosol'' co ...

s and take effect through inhalation. Due to their volatility, they are more toxic in confined areas than in open areas. Cyanide compounds occur in small amounts in the natural environment and in cigarette smoke. They are also used in several industrial processes and as pesticides. Cyanides are released when

synthetic fabric Synthetic may refer to: Science * Synthetic biology * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic elements, chemical elements that are not naturally found on Earth and therefore have to be created in ...

s or

polyurethane Polyurethane (; often abbreviated PUR and PU) is a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term ...

burn, and may thus contribute to fire-related deaths.Walsh, 151. Arsine gas, formed when

encounters an acid, is used as a pesticide and in the semiconductor industry; most exposures to it occur accidentally in the workplace.

Symptoms

The symptoms of blood agent poisoning depend on concentration and duration. Cyanide-based blood agents irritate the eyes and the respiratory tract, while arsine is nonirritating.

Hydrogen cyanide Hydrogen cyanide (formerly known as prussic acid) is a chemical compound with the chemical formula, formula HCN and structural formula . It is a highly toxic and flammable liquid that boiling, boils slightly above room temperature, at . HCN is ...

has a faint, bitter, almond odor that only about half of all people can smell. Arsine has a very faint garlic odor detectable only at greater than fatal concentrations. Exposure to small amounts of cyanide has no effect. Higher concentrations cause dizziness, weakness and nausea, which cease with the exposure, but long-time exposure can cause mild symptoms followed by permanent brain damage and muscle paralysis. Moderate exposure causes stronger and longer-lasting symptoms, including headache, that can be followed by convulsions and coma. Stronger or longer exposure will also lead to convulsions and coma. Very strong exposure causes severe toxic effects within seconds, and rapid death. The blood of people killed by blood agents is bright red, because the agents inhibit the use of the oxygen in it by the body's cells. Cyanide poisoning can be detected by the presence of thiocyanate or cyanide in the blood, a smell of bitter almonds, or respiratory tract inflammations and congestions in the case of cyanogen chloride poisoning. There is no specific test for arsine poisoning, but it may leave a garlic smell on the victim's breath.

Effects

At sufficient concentrations, blood agents can quickly saturate the blood and cause death in a matter of minutes or seconds. They cause powerful gasping for breath, violent convulsions and a painful death that can take several minutes. The immediate cause of death is usually

respiratory failure Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a r ...

. Blood agents work at the cellular level by preventing the exchange of

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

and

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

between the blood and the body's cells. This causes the cells to suffocate from lack of oxygen. Cyanide-based agents do so by interrupting the

electron transport chain An electron transport chain (ETC) is a series of protein complexes and other molecules which transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples th ...

in the inner membranes of mitochondria. Arsine damages the red blood cells which deliver oxygen throughout the body.

Detection and countermeasures

Chemical detection methods, in the form of kits or testing strips, exist for hydrogen cyanide. Ordinary clothing provides some protection, but proper protective clothing and masks are recommended. Mask filters containing only charcoal are ineffective, and effective filters are quickly saturated. Due to their high volatility, cyanide agents generally need no decontamination. In enclosed areas, fire extinguishers spraying sodium carbonate can decontaminate hydrogen cyanide, but the resulting metal salts remain poisonous on contact. Liquid hydrogen cyanide can be flushed with water.Ledgard
73
Cyanide poisoning can be treated with antidotes.

List of blood agents

The information in the following table, which lists blood agents of military significance,Ledgard
72
is taken from Ledgard. The values given are on a scale from 1 to 10. Sodium cyanide and potassium cyanide, colorless crystalline compounds similar in appearance to sugar, also act as blood agents.

Carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

could technically be called a blood agent because it binds with oxygen-carrying hemoglobin in the blood (see

carbon monoxide poisoning Carbon monoxide poisoning typically occurs from breathing in carbon monoxide (CO) at excessive levels. Symptoms are often described as " flu-like" and commonly include headache, dizziness, weakness, vomiting, chest pain, and confusion. Large ...

), but its high volatility makes it impractical as a chemical warfare agent. One of the earliest proposed chemical weapons, cacodyl oxide, or Cadet's fuming liquid, also displays properties of a blood agent (as well as those of a malodorant). It was proposed as a chemical weapon in the British Empire during the

Crimean War The Crimean War was fought between the Russian Empire and an alliance of the Ottoman Empire, the Second French Empire, the United Kingdom of Great Britain and Ireland, and the Kingdom of Sardinia (1720–1861), Kingdom of Sardinia-Piedmont fro ...

, along with the significantly more potent blood agent, cacodyl cyanide.

Use

The most significant practical application of blood agents was the use of

hydrogen cyanide Hydrogen cyanide (formerly known as prussic acid) is a chemical compound with the chemical formula, formula HCN and structural formula . It is a highly toxic and flammable liquid that boiling, boils slightly above room temperature, at . HCN is ...

( Zyklon B) in gas chambers by

Nazi Germany Nazi Germany, officially known as the German Reich and later the Greater German Reich, was the German Reich, German state between 1933 and 1945, when Adolf Hitler and the Nazi Party controlled the country, transforming it into a Totalit ...

to commit the mass murder of Jews and others in the course of

the Holocaust The Holocaust (), known in Hebrew language, Hebrew as the (), was the genocide of History of the Jews in Europe, European Jews during World War II. From 1941 to 1945, Nazi Germany and Collaboration with Nazi Germany and Fascist Italy ...

. This resulted in the largest death toll as a result of the use of chemical agents to date. Hayes, Peter (2004). ''From Cooperation to Complicity: Degussa in the Third Reich'', pp. 2, 272.

References

{{Chemical warfare