CR gas or dibenzoxazepine (chemical name dibenz 'b'',''f''1,4]oxazepine, is an

incapacitating agent Incapacitating agent is a chemical or biological agent which renders a person unable to harm themselves or others, regardless of consciousness. Lethal agents are primarily intended to kill, but incapacitating agents can also kill if administered ...

and a lachrymatory agent. CR was developed by the British

Ministry of Defence A ministry of defence or defense (see American and British English spelling differences#-ce.2C -se, spelling differences), also known as a department of defence or defense, is the part of a government responsible for matters of defence and Mi ...

as a riot control agent in the late 1950s and early 1960s. A report from the Porton Down laboratories described exposure as "like being thrown blindfolded into a bed of

stinging nettle ''Urtica dioica'', often known as common nettle, burn nettle, stinging nettle (although not all plants of this species sting) or nettle leaf, or just a nettle or stinger, is a herbaceous perennial flowering plant in the family Urticaceae. Or ...

s", and it earned the nickname "firegas". In its effects, CR gas is very similar to

CS gas The compound 2-chlorobenzalmalononitrile (also called ''o''-chlorobenzylidene malononitrile; chemical formula: C10H5ClN2), a cyanocarbon, is the defining component of the lachrymatory agent commonly referred to as CS gas, a tear gas which ...

(''o''-chlorobenzylidene malononitrile), but twice as potent, even though there is little structural resemblance between the two. For example, 2 mg of dry CR causes skin redness in 10 min, 5 mg causes burning and erythremia, and strong pain. Water usually amplifies the pain effect of CR on skin. CR aerosols cause irritation at concentrations of 0.2 mcg/L, becoming intolerable at 3 mcg/L. The of CR through air inhalation 350 mg·min/L.

Physical properties and deployment

CR is a pale yellow crystalline solid with a spicy odor. It is slightly soluble in water and does not degrade in it. CR is usually presented as a microparticulate solid, in the form of suspension in a

propylene glycol Propylene glycol ( IUPAC name: propane-1,2-diol) is a viscous, colorless liquid. It is almost odorless and has a faintly sweet taste. Its chemical formula is CH3CH(OH)CH2OH. As it contains two alcohol groups, it is classified as a diol. An al ...

-based liquid. Contrary to its common name, it is not a gas but a solid at room temperature. The dibenz ,f1,4]oxazepine Moiety (chemistry), moiety is present in the

typical antipsychotic Typical antipsychotics (also known as major tranquilizers, and first generation antipsychotics) are a class of antipsychotic drugs first developed in the 1950s and used to treat psychosis (in particular, schizophrenia). Typical antipsychotics m ...

drug A drug is any chemical substance other than a nutrient or an essential dietary ingredient, which, when administered to a living organism, produces a biological effect. Consumption of drugs can be via insufflation (medicine), inhalation, drug i ...

loxapine, but, unlike CR, loxapine is not reactive and is not an irritant. CR was first synthesised in 1962. CR can be delivered either as an aerosol or a solution in water, making it able to be used in water cannons, smoke grenades, or handheld spray cans. For smoke it is usually fired in canisters (LACR) that heat up, producing an

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 ...

cloud at a steady rate.

Effects

CR gas is a lachrymatory agent (LA), exerting its effects through activation of the

TRPA1 Transient receptor potential cation channel, subfamily A, member 1, also known as transient receptor potential ankyrin 1, TRPA1, or The Mustard and Wasabi Receptor, is a protein that in humans is encoded by the ''TRPA1'' (and in mice and rats by ...

channel. Its effects are approximately 6 to 10 times more powerful than those of

. CR causes intense skin irritation, in particular around moist areas;

blepharospasm Blepharospasm is a neurological disorder characterized by intermittent, involuntary spasms and contractions of the orbicularis oculi muscle, orbicularis oculi (eyelid) muscles around both eyes. These result in abnormal twitching or blinking, an ...

, causing temporary blindness; and coughing, gasping for breath, and panic. It is capable of causing immediate incapacitation. It is a suspected

carcinogen 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 ...

. It is toxic, but less so than CS gas, by ingestion and exposure. However, it can be lethal in large quantities. In a poorly ventilated space, an individual may inhale a lethal dose within minutes. Death is caused by

asphyxiation Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects all the tissues and organs, some more rapidly than others. There are ...

and

pulmonary edema Pulmonary edema (British English: oedema), also known as pulmonary congestion, is excessive fluid accumulation in the tissue or air spaces (usually alveoli) of the lungs. This leads to impaired gas exchange, most often leading to shortness ...

. The effect of CR is long-term and persistent. CR can persist on surfaces, especially porous ones, for up to 60 days.

Treatment

While CS can be decontaminated with a large amount of water, use of water may exacerbate the effects of CR. Skin contaminated with CR gas may become extremely painful in contact with water for up to 48 hours after contamination. Medical treatment is mostly palliative. The contaminated clothing has to be removed. The eyes and skin can be washed, the eye pain can be alleviated with medications.

Use

Egypt

During the 2011 protests against the military government in Egypt, Egyptian security forces allegedly used CR gas in addition to the more commonly used, less debilitating CS gas. One protester described the gas as making him feel "as if your eyes are about to fall out; then you have trouble breathing, and you lose your sight". Egyptians used yeast as a treatment for CR side effects on skin. Mohammed ElBaradei also confirmed via Twitter that "tear gas with

nerve agent Nerve agents, sometimes also called nerve gases, are a class of organic chemistry, organic chemicals that disrupt the mechanisms by which nerves transfer messages to organs. The disruption is caused by the blocking of acetylcholinesterase (ACh ...

" is being used in

Tahrir Square Tahrir Square (, ; ), also known as Martyr Square, is a public town square in downtown Cairo, Egypt. The square has been the location and focus for political demonstrations. The 2011 Egyptian revolution and the resignation of President of Egypt, ...

. The only gas that has been identified by human rights organizations in protests "is CS tear gas, typically used by police forces to disperse crowds," stated Egyptian journalist Farida Helmy. Egyptian use of CR gas has not been corroborated according to

Human Rights Watch Human Rights Watch (HRW) is an international non-governmental organization that conducts research and advocacy on human rights. Headquartered in New York City, the group investigates and reports on issues including War crime, war crimes, crim ...

France

People occupying an area in Notre-Dame-des-Landes against an airport project suspect the use of CR gas by French Police and Army in April 2018.

Northern Ireland

It started being available in police and army supplies, as a water cannon additive and as spray cans, in 1973 and was at least still so in 1981. Republican groups in Northern Ireland have alleged that British Army and Royal Ulster Constabulary units used CR gas against Republican prisoners in the 1970s. Additionally, there are British military documents now declassified and in the public domain held in the records of the UK Ministry of Defence at the National Archives, London, that suggest that the British Army did deploy and use CR gas in Northern Ireland.

Philippines

CR tear gas was used in suppression of the mutiny in Makati that was led by Sen. Antonio Trillanes. The tear gas was fired in the building and all the people in the building including reporters were affected.

South Africa

In the late 1980s, CR was used in the townships in

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

. It caused some fatalities, in particular among children.

Sri Lanka

The Tamil Tigers of Sri Lanka, an insurgent group in Sri Lanka used CR gas against government forces that were on an offensive to flush and defeat these insurgents during September 2008. Its use hindered the army's progress but ultimately proved ineffective in preventing the army from overrunning their positions. This is one of the first few cases of insurgents using CR gas as an insurgent weapon.

Turkey

In the June 2013 protest against the Turkish government, Turkish police allegedly used CR gas on protesters in Istanbul. Doctors in a makeshift first aid post in a Mosque judged it as such.

Ukraine

In Ukraine, CR gas was commonly used by special forces against demonstrators. Gas is packed in a form of spray cans "Cobra 1". For example, gas had been used on a demonstration dedicated to the Ukraine Independence Day (24 August 2011). Also gas usage has been documented during demonstrations against Language Law Draft in Kyiv on 3 and 4 July 2012.

References

{{Chemical classes of psychoactive drugs Lachrymatory agents Riot control agents Dibenzoxazepines