From Hong Kong to Kashmir: The devastating effects of tear gas on our body
This Sunday in Hong Kong, police again used tear gas to disperse pro-democracy protesters: in June, people started pouring into the streets to speak up against a proposal to try Hong Kong citizens in courts on mainland China. Protests have since grown to take over streets, airports and hospitals there.
The use of teargas isn’t new, of course. Historians say that the first tear gas canister was probably thrown in August 1914, 105 years ago, during World War I. The idea, then, was to bring enemy troops out from behind their barricades.
Cut to the present-day, police forces around the world use it to control large crowds. While teargas is, without doubt, a safer option than actual bullets (this weekend, Hong Kong police also fired a live round and used a water cannon against protesters), yet the effects on the body can be quite devastating.
What is tear gas?
The active compounds in tear gas are o-chlorobenzylidene malononitrile (CS), dibenzoxazepine (CR) and phenacyl chloride (CN). These compounds are used as riot control agents (RCA), as they stimulate the corneal nerves in the eyes and cause tearing - they are collectively known as tear gas.
In July 2016, researchers Craig Rothenberg et. al wrote in the Annals of the New York Academy of Sciences: “Tear gas use has dramatically increased in recent years, with very large amounts released in population centers in Turkey, United States, Hong Kong, Greece, Brazil, Egypt, and Bahrain.”
How does it affect our body?
Tear gas has a dramatic effect on the body. It starts acting within 20 seconds of exposure and starts to wear off within 15 minutes of cessation. CS is the most commonly used tear gas in the world.
“Specifically, all tear gas agents activate one of two pain receptors, TRPA1 or TRPV1, and can be classified into two broad categories based on which of those receptors they activate,” columnist Angus Chen wrote in 'How Tear Gas Works: A Rundown of the Chemicals Used on Crowds', a November 2018 article in the Scientific American. "The first category, TRPA1-activating agents, includes the chemical called 2-chlorobenzalmalonitrile or CS gas. This is one of the agents used by U.S. law enforcement," he wrote.
Chen added that some formulations of CS now contain silicone, which lingers in the environment and causes even greater suffering.
According to the U.S. Center for Communicable Diseases, the effects of CS tear gas on the body include “pain, burn(ing) eyes, lacrimation (discharge of tears), conjunctivitis; erythema (skin redness) eyelids, blepharospasm; irritation throat, cough, chest tightness; headache; erythema (skin redness), vesiculation skin”.
The other two substances in tear gas, CR and CN, are more potent than CS. Just after the Arab Spring protests in 2011, Sven-Eric Jordt, an associate professor of anesthesiology at Duke University, wrote that more than the usual number of miscarriages were being reported in pregnant women who were exposed to these gases, “probably due to shock and stress and the chemical exposure”.
Long-term effects of tear gas include worsening of asthma, dysregulation in cardiovascular function, respiratory obstruction. Heavy exposure may also cause skin burns and dermatitis, especially when CN gas is used.
Though pharmaceutical companies are trying, so far there isn’t a counteractive agent that can undo the effects of tear gas.
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Updated Date: Aug 28, 2019 12:21:54 IST
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