Binary Agents

Weapons of mass destruction aren't pulled out of a black hat like a white rabbit at a magic show. They're produced in factories. There's science and technology involved. They're not produced in a hole in the ground or in a basement.

Scott Ritter, United Nations Weapons Inspector

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In chemical warfare, a binary weapon is defined as a CW agent where the agent is produced during the flying time of the ammunition (rocket, missile, shell, or grenade) towards the target. The claimed purpose of this kind of CW agent is to reduce the risks in the production, storage, transport, and even destruction of the toxic agent. This is possible because the starting materials are relatively non-toxic precursors. For this task to be feasible the reaction has to be controlled to avoid overheating or explosion during the flight. Also, it should preferably run without solvent and has to be completed, with a high yield, in a matter of seconds. Usually the body of a binary projectile contains two separate canisters, one behind the other, each containing one starting material. The force of launching causes the breaking of the canisters, which mixes the starting materials and triggers the reaction to produce the chemical agent, alternative mechanisms have been developed.

The idea of designing this kind of ammunition originates from World War II, when military chemists developed, but never used, a binary bomb to deliver the blood agent arsine. The vesicant N-(2-chloroethyl)-N-nitrosocarbamate  [C₅H₈Cl₂N₂O₃] was also considered as a potential binary weapon in the 1940s, but never fully developed. The first nerve agents developed as binary weapons were GB-2, GD-2, and VX-2, the binary versions of sarin, soman, and VX, respectively. They were all developed by the USA during the Cold War  they have been called  the third generation of CW agents.

The first weapon designed to use binary agents was the American BL80 "BIGEYE" bomb. BIGEYE was an air-launched 500 pound-class canister weapon to be delivered by various U.S. Navy and Air Force aircraft. The interior of the weapon consisted of two separate containers of non-lethal chemical compounds, stored separately and assembled only immediately before flight, and then combined to create the active chemical nerve agent VX only after release from the aircraft. It was the storage separation of less aggressive chemical components that ensured safe storage/handling and simpler maintenance requirements. The bomb was a Navy design that would atomize the percutaneous nerve agent VX over a targeted area by releasing the binary-generated agent while gliding through the air over the target. The bomb weighed 595 lb (270 kg) and would have generated the chemical agent VX. It was to have a length of 7 ft 6 in (2.29 m) and a diameter of 13.25 in (337 mm). It was a glide bomb with a wingspan of 1 ft 5.25 in (43.81 cm). BIGEYE was not planned to have any internal guidance, propulsion or autopilot systems (hence its "glide bomb" designation). Bigeye produced VX2 as described below. It was originally designed in the 1960s and production ended in 1990.

In the open literature little is known about agents developed in the Soviet Union. They are thought to be five to ten times more toxic than VX  The toxicity of these binary agents does not rely primarily on the inhibition of acetylcholinesterase, but it is thought that it causes permanent neuropathy. Consequently, conventional nerve agent antidotes (atropine sulfate and pralidoxime chloride) may not work. Reactive oximes such as potassium 2,3-butanedione monoximate may be use in detoxification.

Known binary agents include the following:

GB-2: (binary sarin, GB-2)

There are several reported precursors for GB-2. The most frequently reported is the reaction of methylphosphonic difluoride (DF) [CH₃F₂OP] located in 1 canister, while a mixture of isopropyl alcohol [CH₃CHOHCH₃] and isopropylamine [(CH₃)₂CHNH₂]solution (OPA) is in the second canister. The isopropyl amine binds to the hydrogen fluoride generated during the chemical reaction. After deployment of the weapon, the 2 canisters rupture and the chemical mixture produces sarin.Binary Sarin is exactly the same as conventional Sarin, once formed. Sarin is a potent organophosphorus nerve agent that inhibits acetylcholinesterase irreversibly. The subsequent build-up of acetylcholine in the central nervous system provokes seizures and, at sufficient doses, centrally-mediated respiratory arrest. Accumulation of ACh to peripheral signs of intoxication and overstimulation of the muscarinic and nicotinic receptors, which is described as “cholinergic crisis” (i.e. diarrhea, sweating, salivation, miosis, bronchoconstriction). Exposure to high doses of sarin can result in tremors, seizures, and hypothermia. More seriously, build-up of ACh at neuromuscular junctions also can cause paralysis and ultimately peripherally-mediated respiratory arrest which can lead to death via respiratory failure. In addition to its primary action on the cholinergic system, sarin possesses other indirect effects. These involve the activation of several neurotransmitters including gamma-amino-butyric acid (GABA) and the alteration of other signaling systems such as ion channels, cell adhesion molecules, and inflammatory regulators. Sarin exposure is associated with symptoms of organophosphate-induced delayed neurotoxicity (OPIDN) and organophosphate-induced chronic neurotoxicity. The standard treatment for sarin-like nerve agent exposure is post-exposure injection of atropine, a muscarinic receptor antagonist, accompanied by an oxime, an AChE reactivator, and diazepam.

GD-2 binary (binary Soman, GD2):

Methylphosphonic difluoride (DF) [CH₃F₂OP] is located in 1 canister, while a mixture of pinacolyl alcohol [C₆H₁₄O] and an amine [R-NH₂] is in a second canister. After deployment of the weapon, the 2 canisters rupture and the chemical mixture produces GD. Once formed binary Soman has all the same properties as the conventionally manufactured Soman. Compared with other nerve agents, soman is more volatile than VX (the strongest nerve agent) but less volatile than sarin. Higher volatility means it is more likely to evaporate from a liquid into a gas and spread into the environment.

Because soman is more volatile than VX, it will stay on surfaces for a shorter period of time compared with VX. People can be exposed to the gas even if they do not come in contact with the liquid form. Because of its high volatility, soman is an immediate but short-lived threat. Soman does not last a long time in the environment.

The level of soman poisoning depends on the amount of soman, how the person was exposed, and for how long. Symptoms will likely appear within a few seconds after exposure to the vapor or liquid form of soman.

People can be exposed to soman by breathing it in, swallowing, or through skin absorption. Exposure to a low or medium amount can cause some or all of the following symptoms within seconds to hours: abnormally low or high blood pressure, blurred vision, chest tightness, confusion, cough, diarrhea, drooling, excessive sweating, drowsiness, eye pain, headache, increased urination, nausea, vomiting, abdominal pain, rapid breathing, runny nose, low or fast heart rate, small pinpoint pupils, muscular weakness. Even a tiny drop of nerve agent on the skin can cause sweating and muscle twitching where the agent touched.

Exposure to a large amount of soman in any way can cause these additional negative health effects: convulsions, loss of consciousness, paralysis, respiratory failure possibly leading to death.

VX2 binary (VX2):

Isopropyl aminoethylmethyl phosphonite (QL) [C₁₁H₂₆NO₂P] is in 1 canister. The other canister contains elemental sulfur[S]. When the weapon is fired, the canisters rupture and the chemical mixture produces VX. Binary VX is the same as VX manufactured conventionally. Like all nerve agents, VX stops certain enzymes from working. When these enzymes do not work correctly, muscles are constantly being used. As a result, people may become tired and no longer be able to keep breathing.

VX can remain in the environment from days to months depending on the circumstances. VX is an oily liquid, amber in colour, it is tasteless odourless, it is slow to evaporate and become a vapour it evaporates as slowly as motor oil.

Signs and symptoms of exposure depend on how much a person was exposed to, how the person was exposed, and for how long. Until signs and symptoms develop, people may not know that they were exposed.

Exposure to a low or medium amount may cause some or all the following signs and symptoms within seconds to hours: abnormally low or high blood pressure, blurred vision, eye pain, lachrymation, chest tightness, confusion, cough, diarrhea, drooling, difficulty breathing, drowsiness, excessive sweating, fast or slow heart rate, headache, increased urination, muscle cramps, nausea, vomiting, abdominal pain, rapid breathing, runny nose, shortness of breath, small pinpoint pupils, tremors, muscular weakness, wheezing.
Even a small drop of VX on the skin can cause sweating and muscle twitching where it touched the skin.

Exposure to large amount of VX in any way may result in the following harmful health effects: loss of consciousness, cardiac arrest, coma, convulsions, paralysis, respiratory failure, seizures, twitching.

Because VX evaporates slowly, VX can be a short-term threat or a long-term threat. VX can stay on surfaces and be dangerous for days to months.

Novichok agents:

Not all novichok agents are binary, but binary versions have been made of several of them. Not much is known about these agents. The symptoms are similar to those of other nerve agents. In the open literature little is known about these agents developed in the Soviet Union. They are thought to be five to ten times more toxic than VX  The toxicity of these binary agents does not rely primarily on the inhibition of acetylcholinesterase, but it is thought that it causes permanent neuropathy. Consequently, conventional nerve agent antidotes (atropine sulfate and pralidoxime chloride) may not work. Reactive oximes such as potassium 2,3-butanedione monoximate may be use in detoxification.

Substance 33:

Possibly produced from the reaction between 2-methylpropyl methylphosphonocyanidate (PCN) [C₅H₁₂FO₂P] and 2-(diethylamino)ethanethiol [C₆H₁₆ClNS] (DEAT)

A-232:

Possibly produced from the reaction between methyl phosphorocyanidofluoridate [CH₃F₂O₂P] (PCF) and N,N-diethyl-2-iminopropan-1-amine [C₇H₁₆N₂] (NNDA).

A-234 (3-chloro-2-methylbutyl((chlorofluoromethylene)amino)oxyphosphonofluoridate, Novichok 7)

Details unknown.

Other countries believed to have developed binary agents include Syria, Iraq and North and South Korea.