You’ve already seen the photo: A woman on the U.S.-Mexico border grips two young children by their arms as they run from a plume of smoke hissing from a canister. The twin girls are wearing diapers; one is barefoot.
Pelting children seeking asylum with tear gas is perfectly fine, the Trump administration and conservative commentators assured the public on Sunday. “It’s natural. You could actually put it on your nachos and eat it,” Border Patrol Foundation President Ron Colburn falsely claimed in a Fox News interview about the gas.
Tear gas is not edible, nor is it a recommended nacho topping. It is a chemical agent known as a lachrymator (from “lacrima,” Latin for “tear”) that causes eyes to well, mucous membranes to burn, throats to constrict. It is meant not just to smother, but to confuse, intimidate and terrify. It provides a useful smokescreen for governments that want to suppress popular movements, whether that means civilians protesting police brutality or refugees seeking safe harbor.
History shows that governments are often quick to escalate from tear gas to more brutal — and lethal — attacks. In 1965, on Edmund Pettus Bridge, Alabama state troopers shot dozens of canisters of tear gas canisters at peaceful civil rights protesters. As the protesters screamed and choked, the tear gas provided an effective smokescreen for police as they began clubbing protesters with batons.
Released as an aerosol, tear gas is impossible to contain. And as an airborne chemical agent, it does not care if the eyes, noses and lungs it meets are those of an enemy combatant or of a child fleeing for safety. Inhaling the gas — particularly in confined spaces or for long periods of time — has been linked with long-term respiratory damage, blindness and even death. In 2011, the Chilean government prohibited police from using tear gas after a study from the University of Chile found that tear gas exposure could lead to miscarriage.
No country is legally obligated to keep records of its use of tear gas, or of the number of deaths or injuries resulting from its use, and government agencies aren’t keen to release such data. That lack of information gives governments cover to continue claiming the gas is harmless while implicitly justifying its future use against civilians, not just as a physical agent, but also a psychological one. From Ferguson to Palestine, from Irvine to Syria, government forces have deployed pepper spray on civilians with zeal.
The first documented use of tear gas dates back to World War I, but scholars have suggested that the substance may have first been developed a half-century earlier, in response to the populist uprisings across Europe in 1848. In her 2017 book, Tear Gas: From the Battlefields of WWI to the Streets of Today, author Anna Feigenbaum writes that in the wake of the 1848 revolution, the French government sought out “a weapon that could penetrate barricades in ways that gun and even cannon fire could not. Likewise, they needed a technique to demoralize and disorient, breaking the collective spirit that formed behind the barricade wall.”
The value of tear gas as an agent of fear was clear from its inception. “Early advertisements in trade magazines sold tear gas as a security solution for home invaders, burglars, bank robbers, prisoners, and most importantly, protesters,” Feigenbaum writes in her book. “One such advertisement claimed, ‘It is easier for man to maintain morale in the face of bullets than in the presence of invisible gas.’ It argued that, unlike bullets, tear gas would ‘isolate the individual from the mob spirit’ and make the mob ‘a blind stampede to get away from the source of torture.’”
The widespread use of chemical weapons during World War I, including chlorine and mustard gas, led to an estimated 1.3 million casualties. In response to this new and destructive form of warfare, the United States and other countries signed on to the 1925 Geneva Protocol (and later, the 1993 Chemical Weapons Convention) which prohibited countries from using chemical agents in on the battlefield.
But, paradoxically, tear gas remains legal for countries to use against their own citizens. Look to nearly any popular uprising in the past 30 years, and you will see images like the ones that came out of Tijuana on Sunday. The type of tear gas riot police typically use is known as CS gas, which is derived from a chemical compound discovered by two chemists at Middlebury College in 1928. It has become the crowd control weapon of choice for police and military forces around the world.
In June of 2013, Turkish Prime Minister Recep Tayyip Erdogan ordered riot police to use tear gas, rubber bullets and water cannons on citizens protesting the government’s plans to bulldoze a park in Istanbul to build a shopping mall. According to local news outlets, Turkish police deployed 130,000 tear gas canisters on protesters over the course of three weeks. The violence killed five people and left thousands injured.
Three months after the initial protests, the Turkish Medical Association found that 39 percent of protesters still suffered health effects stemming from their exposure to tear gas, including skin irritation, dizziness and balance problems. The same report found that at least 11 people had lost an eye as a result of being hit in the face with a tear gas canister or plastic bullets.
In 2014, tear gas became synonymous with the protests in Ferguson, Missouri, over the killing of 18-year-old Michael Brown Jr. In a now-iconic photo, protester Edward Crawford, wearing an American flag tank top, threw a tear gas canister back at the police (Crawford, 27, was found dead in his car last year, from what police say was a self-inflicted gunshot wound.)
Even the deployment of tear gas on the border isn’t a new phenomenon. Customs and Border Protection data indicate that border patrol agents used tear gas 126 times since fiscal year 2012. But the practice has intensified under President Donald Trump, who has called for the use of “lethal force” if necessary to keep asylum-seekers out. That call represents an opening volley for a government intent on controlling people by sheer force and vilifying anyone who opposes the government’s agenda. Around the world, the arguments governments use to justify turning tear gas on civilians are the same.They start by arguing tear gas is harmless, and end by claiming civilians armed with rocks and bottles pose as much of a threat as soldiers operating with the full force of the military behind them. When government leaders further escalate their response, the citizenry is primed to accept it as standard operating procedure.
In a photo shared by NBC News, Maria Meza, the Honduran woman seen in the now-infamous photo with her children, holds up one of the gas canisters used against refugees at the border. The canister appears to have been produced by Defense Technology, a Jacksonville-based weapons manufacturer owned by the Safariland Group. The U.S. is the leading manufacturer of tear gas.
“Together,” Safariland’s mission statement reads, “we save lives.”
This article originally appeared on HuffPost.