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CS gas

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CS gas
Chemical structure of CS
General
IUPAC 2-Chlorobenzalmalononitrile
Other names
CS Gas
Tear gas
ortho-chlorobenzylidene malononitrile
Propanedinitrile, [(2-chlorophenyl)methylene]
Malononitrile, (o-chlorobenzylidene)
β,β-Dicyano-o-chlorostyrene
(o-Chlorobenzal)malononitrile
(o-Chlorobenzylidene)malononitrile
2-Chlorobenzylidenemalononitrile
(o-Chlorobenzylidene)malonitrile
o-Chlorobenzylidenemalonic nitrile
NCI-C55118
USAF KF-11
2-Chloro BMN
b,b-Dicyano-O-chlorostyrene
2-Chlorobenzylidenemaloninitrile
Propanedinitrile, 2-2-chlorobenzylidene
2-(2-Chlorobenzylidene)malononitrile
Molecular formula C10H5Cl N2
Molar mass 188.6 g/mol [1]
Appearance White crystalline powder,
Colourless gas when burned.
CAS number [2698-41-1]
Properties [2]
Density/phase 1.04 g/cm3, solid
Soluble MiBK, hexane, benzene,
methylene chloride, acetone,
dioxane, ethyl acetate,
and pyridine.
Insoluble ethanol, water
Freezing point 93°C, (366.15 K), (199.4 °F)
Boiling point [3] 310 °C, (583.15 K), (590 °F)
Vapor pressure (mm Hg) 3.4 x 10-5 @ 20°C
Volatility 0.71 mg/m3 @ 25 C
Toxicity Values ICt50 = 10 to 20 mg-min/m3
LCt50 = 61,000 mg-min/m3
Exposure Limits Workplace Time-Weighted Average:
0.4 mg/m3
General Population Limits:
No standard identified
Related
compounds
SDBS 		5-chloro-2-quinolinecarbonitrile
6-chloro-2-quinolinecarbonitrile
7-chloro-2-quinolinecarbonitrile

CS or 2-chlorobenzalmalononitrile (chemical formula: C10H5ClN2) is a substance that is used as a riot control agent and is usually claimed to be non-lethal by the forces who use it. CS was discovered by two Americans, Ben Carson and Roger Staughton in 1928, the first letters of the scientists' surname giving us the name of the substance, 'CS' [4]. It was developed and tested secretly at Porton Down in Wiltshire, England. Apparently this testing occurred in the 1950s and 1960s when CS was used firstly on animals, then subsequently on British Army servicemen volunteers. Notably CS has a limited effect on animals due to "under-developed tear-ducts and protection by fur". [5].

Production

It is synthezed by the reaction of 2-chlorobenzaldehyde and malononitrile (malonic acid) via the Knoevenagel condensation:

ClC6H4CHO + H2C(CN)2 → ClC6H4CHC(CN)2 + H2O

'CS Gas' - a misnomer

In common parlance CS is referred to as 'CS gas' or 'Tear gas', however this description is incorrect because 2-chlorobenzalmalononitrile is a solid at room temperature, not a gas. A variety of techniques have been used to make this solid usable as an airborne irritant. For example in Waco, Texas, CS was dispersed in droplet form. CS was dissolved in the organic solvent Methylene chloride (MC) and when this evaporated, the CS crystallized into fine particles [1].

It is worth noting that many types of tear gas have been produced with effects ranging from mild tearing of the eyes to immediate vomiting and prostration. CN and CS are the most widely used and known, but around 15 different types of tear gas tested worldwide. CS has become the most popular due to its strong effect and lack of toxicity in comparison with other similar chemical agents. The effect of CS on a person will depend on whether it is packaged as a solution, or if it is an aerosol; the size of solution droplets and the size of the CS particulates after evaporation, are factors determining it's effect on the human body. Certain individuals however have been found to be particularly sensitive to CS and or the organic solvents that are utilised. Studies on the use of CS on the public have noted that it may be ineffective against persons who are either mentally ill or who are under the effects of alcohol [6].

Preparations

Melted and sprayed in the molten form.
Dissolved in organic solvent.
CS2 dry powder (CS2 is a siliconized, micro-pulverized form of CS).
CS from thermal grenades by generation of hot gases [1].

CS incapacitant spray

CS Incapacitant Spray is used as a temporary incapacitant, to subdue attackers, or persons who are violently aggressive, by many police forces. The chemical reacts with moisture on the skin and in the eyes causing a burning sensation and the immediate forceful shutting of the eyes. Reported effects can include tears streaming from the eyes, running nose full of mucus, burning in the nose and throat areas, disorientation, dizziness and restricted breathing. In highly concentrated doses it can also induce severe coughing and vomiting.

Although predominantly used by police forces it has also been used in criminal attacks in various countries. [7] [8] [9] [10].

CS is banned from use in war by the 1997 Chemical Weapons Convention (signed 1993), as it's use could be a trigger for full scale chemical warfare, however domestic police use is legal in many countries.

Use geographically

CS was used to flush the Viet Cong from their tunnels in Vietnam.

Cyprus

CS was first tested in the field by the British army in Cyprus in 1958. At this time it was known by the code name T792 [11].

Vietnam

It has been reported that thousands of tons of CS gas were used by the U.S. forces in Vietnam to bring Viet Cong into the open [12], other estimates report 15 million pounds of CS being used [13].

File:Mural - Battle of the bogside 2004 SMC.jpg
A boy in a gas mask during the Battle of the Bogside.

Northern Ireland

CS gas was heavily used in the Bogside area of Derry, Northern Ireland during the "Battle of the Bogside", a two-day riot in August, 1969. A total of 1,091 canisters containing 12.5g of CS; and 14 canisters containing 50g of CS, were released in the densely populated residential area [14]. On 30 August the Himsworth Inquiry was set up to investigate the medical effects of its use in Derry. Its conclusions, viewed in the political context of the time, still pointed towards the necessity of further testing of CS gas before being used as a riot control agent. Not long after, the British Army and RUC ceased using CS in Northern Ireland. Up to this point, it had been used in crowd control scenarios in Derry and Belfast.

Iraq

Iraq successfully developed CS during the 1970s and during the 1980s produced tons of the substance firstly at Salman Pak and later at al-Muthanna [15]. Saddam Hussein used CS against the Kurds in his own country and against Iran during the Iran-Iraq War.

England & Wales

CS tear gas was first used in mainland Britain to quell rioting in the Toxteth area of Liverpool in 1981. [16]

Personal incapacitant spray (PIS) was sanctioned for use by Police in England and Wales in 1995. [17] The CS preparation in this case is CS dissolved in the organic solvent MiBK, or methyl iso-butyl ketone, an industrial de-greasing agent. The propellant used in this preparation is Nitrogen [18].

It has been noted that the solvent MiBK is itself harmful, and can cause inflammation, dermatitis, burns to the skin & liver damage. [19].

A six month trial by 16 police forces in England began on the 1st March 1996. Only two weeks later, on the 16th of March 1996, a Gambian asylum seeker, Ibrahima Sey was taken to Ilford Police Station in East London. Whilst incapacitating the man, police sprayed him with CS and held him on the ground for over 15 minutes. A verdict of "Unlawful Killing" was given by the jury at the end of the inquiry into his death, no charges were brought against any member of the police force [20].

The forces that do use the PIS in the UK require that police personnel themselves must themselves be sprayed during self-defence training, in order for them to be able to be authorised to carry it as personal protection equipment (PPE). They are also trained in helping the incapacitated person recover quickly once successfully restrained. Forces that do not issue CS Spray to its officers issue PAVA Spray (pelargonic acid vanillylamide aka nonivamide) or Captor Spray.

Notably the CS spray used by UK police has 5 times as much CS as the spray used by American police forces (5% dissolved CS and 1% CS respectively). [21]

In 1999 the UK mental health charity MIND called for a suspension in its use until it is fully tested and there is proof that CS is safe. [22]

More recently, in February 2006 there have been calls to have CS spray banned in the UK after Dan Ford, from Wareham in Dorset, was permanently facially scarred after being sprayed in the face with a police CS canister. Mr Ford was subsequently advised by doctors to stay out of sunlight for at least 12 months. About the incident, his cousin, Donna Lewis, was quoted as saying:

"To look at him, it was like looking at a melting man, with liquid oozing from his face." [23]

USA

CS is used by many police forces within the USA, for example the NYPD, it was most famously used as one of a number of techniques used by FBI law enforcement officials in the 1993 Waco Siege.

Members of the armed forces of the United States of America are often exposed to CS during initial training to show the importance of proper wearing of a gas mask. As the agent's presence quickly reveals improper fit or seal of the mask's rubber gaskets against the face, it is sometimes used during training refresher courses or equipment maintenance exercises as well.

Elsewhere

File:Ftaapolice.png
Police fire tear gas at protesters in Quebec.

CS was used in large quantities to quell a peaceful protest in Lusaka, Zambia in July 1997, Amnesty International reported that it had been manufactured by the UK company Pains-Wessex. Subsequently, Amnesty called for a export ban when the receiving regime is either not fully trained in the use of CS, or had shown usage "contrary to the manufacturer’s instructions". [24]

In September 2000, the Guardian Newspaper revealed how a UK company, HPP, used legal loopholes to export CS to a private security company in Rwanda, in breach of United Nations sanctions. [25] The Guardian also reported that CS was used by the Hutu militia in Rwanda to flush Tutsis out of buildings before hacking them to death.

CS has been used by the government in South Africa; by Israel against Palestinians; by the South Korean government in Seoul, and during the Balkan conflicts.

CS tear gas was used at the G8 protests in Genoa, Italy [26] and Quebec, Canada [27] during the FTAA anti-globalization demonstrations during the Quebec City Summit of the Americas.

Non-lethal?

Although described as a non-lethal weapon for crowd control, many studies have raised doubts about this classification. As well as creating severe pulmonary damage, CS can also significantly damage the heart and liver. [28]

On 28 September 2000, Prof. Dr. Uwe Heinrich released a study commissioned by John C. Danforth, of 'The Office of Special Counsel', to investigate the use of CS by the FBI at the Branch Davidians' Mount Carmel compound. In summary, he concluded that the lethality of CS used would have been determined mainly by two factors: whether gas masks were used, and whether the occupants were trapped in a room. He suggests that if no gas masks were used and the occupants were trapped, then:

"...there is a distinct possibility that this kind of CS exposure can significantly contribute to or even cause lethal effects." [1]

Many reports have associated CS exposure with miscarriages [28], this is consistent with it's reported clastogenic effect (abnormal chromosome change) on mammalian cells.

When CS is metabolized, cyanide can be detected in human tissue. [28]

Decontamination

Decontamination can be performed by washing with an alkaline solution of water and 5% sodium bisulfite.[5]

See also

Polish tear gas grenade launcher.

References

  1. ^ a b c d Study by Uwe Heinrich Documents the chemistry of CS and it's affects on the body. 09 March ,2006)
  2. ^ U.S. Army Center for Health Promotion and Preventive Medicine Detailed Facts About Tear Agent O-Chlorobenzylidene Malononitrile (CS) (pdf)09 March ,2006)
  3. ^ www.wombles.org.uk Article on pepper spray and tear gas.09 March ,2006)
  4. ^ columbia.thefreedictionary.com/
  5. ^ a b Zarc International Inc. CS factsheet
  6. ^ POLICE COMPLAINTS AUTHORITY "SAFER RESTRAINT" - April 2002 (pdf)
  7. ^ Guardian Unlimited CS gas attack by former pupil injures 68 children , October, 1999, Liverpool
  8. ^ irishhealth.com Gas attack at Dublin hospital, May 2004
  9. ^ BBC News online Shopkeeper attacked with CS gas, December 2005, Manchester
  10. ^ BBC News online Car thieves spray gas at motorist, January 2006, Oxted
  11. ^ Final Report of the Expert Panel to Review SAS Veterans’ Health Concerns 2003(pdf)
  12. ^ totse.com The Human Aversion to Killing and the Lie of "Non-Lethal" Weapons
  13. ^ The Austin Chronicle FBI's Use of Tear Gas Questioned at Davidian Trial, Lethal Weapon, by Robert Bryce.
  14. ^ Dr Raymond McClean (1997). The Road To Bloody Sunday (revised edition). Guildhall: Printing Press. ISBN 0-946451-37-0. (extracts available online)
  15. ^ www.iraqwatch.org
  16. ^ BBC News online Riots in Toxteth
  17. ^ An investigation into the short term and medium term health impacts of personal incapacitant sprays. Medical Toxicology Unit, London, UK
  18. ^ The Police Complaints Authority CS SPRAY: INCREASING PUBLIC SAFETY, March 2000. (pdf)
  19. ^ Safety (MSDS) data for methyl isobutyl ketone The Physical and Theoretical Chemistry Laboratory Oxford University
  20. ^ INQUEST, 1997 Report on the death in Police custody of Ibrahima Sey
  21. ^ bmjjournals
  22. ^ BBC News online Statement made by MIND
  23. ^ BBC News online Report on Dan Ford.
  24. ^ Amnesty International Report Stopping the Torture Trade (pdf)
  25. ^ Guardian Unlimited British firms trade in torture
  26. ^ italy.indymedia.org Laura Tartarini, lawyer of Genova Legal Forum
  27. ^ www.nowtoronto.com Foggy Over Tear Gas Safety - Enzo Di Matteo
  28. ^ a b c Tear Gas: Harassing Agent or Toxic Chemical Weapon? The Journal of the American Medical Association

External links

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