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Is tear gas safe? Scientists don’t know.

Minneapolis Police spraying mace at protesters
REUTERS/Eric Miller
Minneapolis Police spraying mace at protesters to break up a gathering near the Minneapolis Police third precinct on May 27.

The use of tear gases for crowd control is rampant, but there exists a significant gap in our knowledge about the effects of these chemicals on an individual’s health, particularly in the long-term. The unknown long-term effects of tear gas exposure warrant cessation of their use until thorough and extensive safety studies have been completed. The use of these agents during the COVID-19 pandemic makes them especially dangerous.

Jennifer Brown
Jennifer Brown
Several different chemicals fall under the tear gas umbrella, with pepper spray and CS gas being the most common. These molecules activate pain receptors in a similar manner to hot peppers, but cause a burning sensation 50 times more intense than a habanero. Tear gases cause well-known acute effects such as runny nose, cough, shortness of breath, phlegm, and chest pain.

Despite the prevalence of their use, little research has been done on their long-term effects, and what research has been done does not unequivocally demonstrate that tear gases are safe. In one study of 93 individuals exposed to tear gas, 24.7% experienced coughing and phlegm for more than three months afterward. More than a third experienced chest tightness and shortness of breath in the year following their exposure. In a 2012 study, military recruits were briefly exposed to tear gas during a training on the proper use of gas masks. Even in that controlled setting, recruits were 2.44 times more likely to contract a respiratory illness in the week following the training than they were in the week leading up to the drill. Another study from Turkey found that men exposed to tear gas were at greater risk for chronic bronchitis.

Carey Lyons
Carey Lyons
Most of the available studies focus on physical effects, but psychological effects are often overlooked. Fear, anxiety, panic, and PTSD could all be persistent psychological reactions to tear gas exposure, but very little research on these effects has been done. For some, the shock and pain of being fired upon can be deadly; a report exists of a 40-year-old man having a heart attack following exposure to pepper spray. Getting a vulnerable individual to a hospital after exposure might not be enough to save them. The breathing problems that are a common effect of acute tear gas exposure can make anesthesia and operating difficult, surgeons say. These problems would be amplified by COVID-19 symptoms.

Even the reported data is not widely generalizable. Only a few studies examine real exposures (i.e. protestors in a crowd) rather than volunteers in a controlled research setting. Additionally, most of the research looks at young, healthy volunteers. Other more at-risk populations have been largely ignored. There is no research at all studying the effects of pepper spray exposure on pregnant women and fetuses. A 2003 Department of Justice report concluded that pepper spray contributed to two in-custody deaths, both involving people with asthma. COVID-19 patients often report trouble breathing, and COVID-19 deaths are often due to respiratory complications. In the middle of a respiratory pandemic, it should be assumed that all individuals have compromised respiratory systems, and deploying aerosolized riot control agents whose long-term effects have not been studied is irresponsible.

Roman Tyshynsky
Roman Tyshynsky
Commentaries on the safety of tear gases, both for scientific and general audiences, appear periodically in times when they are widely used (in 2010 after anti-government protests in Tehran, in 2014 during protests against the killing of Michael Brown in Ferguson, Missouri). These pieces routinely call for additional studies on the safety of tear gas, yet as of June 2020, they are still missing.

Using chemicals with uncertain long-term effects on crowds would not be advisable in the best of times, but is especially risky during a pandemic that affects the respiratory system. It is past time to investigate the possible long-lasting effects of tear gas exposure and prohibit its use domestically until research demonstrates unequivocally that it is safe.

Jennifer Brown, Carey Lyons and Roman Tyshynsky are three graduate students at the University of Minnesota. The turmoil of recent weeks prompted them to use their researching skills on a topic with direct community impact. They hope this piece will be a launching point for larger discussions about the ethics of tear gas use and potential policy changes.


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Comments (8)

  1. Submitted by Michael Qualy on 06/26/2020 - 08:54 am.

    For the user,tear gas keeps the bad guys away or moves them in the direction they need to be moved. For the person being used against, you move or you are affected. Once a political decision to move someone is made,the option after tear gas is clubs or guns , crushing under tank treads. . Which do you think is safer….1) tear gas 2) clubs 3) guns. 4) crushing under tank treads. Minneapolis politicians chose 5) none of the above. $500,000,000 later which is the best decision? Let your politicians know.

    • Submitted by Jeremy Brezovan on 06/26/2020 - 12:38 pm.

      There was nothing political about the police response to protestors (not rioters, but the peaceful protestors who dominated public events the week after George Floyd’s murder)–the police did a great job of demonstrating the need for major reform and de-escalation policies. But thanks for your advocacy of a continued and obviously broken policing model (and desired escalation–tank treads against our own citizens. Really…!?).

    • Submitted by Scott Walters on 06/26/2020 - 02:21 pm.

      The safest option will be the defunding and demilitarization of the police. Looking forward to it. The repudiation of movement conservatism and elimination of the scourge of Republicanism and their ongoing support of institutional racism and policies that entrench multi-generational poverty in the United States will also be a significant advance.

    • Submitted by Eric Snyder on 06/26/2020 - 03:03 pm.

      1. As is overwhelmingly clear from very recent history as well as the entirety of policing, police cannot be trusted to use tear gas responsibly. During recent protests police initiated violent and criminal attacks on a routine basis, threatening the lives and well-being of peaceful protestors. There’s copious amounts of video showing cops tear gassing people for no apparent reason, other than out of apparent malicious delight. Cops were rioting perhaps more often than that rowdy subset of protestors.

      It’ll likely be years, if ever, that we have enough professional and responsible police on the force that would even cause us to consider using tear gas.

      2. The article, while acknowledging gaps in research, already makes a powerful case for stopping the use of tear gas. Alas, we shouldn’t be surprised that in America’s brutish and violent culture that the cops are using a chemical weapons whose health effects are not fully understood. It doesn’t speak well of us that this chemical weapon was allowed to be used in the first place with what we don’t know about it relative to health.

      3. “…tear gas keeps the bad guys away or moves them in the direction they need to be moved.”

      This kind of misrepresentation of how and why tear gas is used has no place in an honest and rational discussion of the issue

      It’s well known that cops will use tear gas as a form of punishment and terror–a decision that frequently has nothing to do with public safety or the maintaining “order” or moving people in the right direction. Indeed, the police often incite the breakdown of peaceful protest–committing crimes as they do so.

  2. Submitted by cory johnson on 06/26/2020 - 09:05 am.

    Last time I checked tear gas is used for riot control not “crowd” control.

  3. Submitted by Curt Carlson on 06/26/2020 - 01:06 pm.

    Tear gas is considered a chemical weapon and banned for military use by the Geneva Conventions. One has to wonder why it’s considered by some to be ok for police to use it against citizens. (Who is it, by the way, that decides the difference between a ‘crowd’ and a ‘riot’?)

  4. Submitted by Rick Slettehaugh on 06/26/2020 - 02:14 pm.

    The use of tear gas in war is banned by international convention. It is unconscionable that we allow it against our own citizens.

  5. Submitted by Paul Udstrand on 06/27/2020 - 12:09 pm.

    People should not expect confrontations like this to “risk free”. Confronting inequality, injustice, racism, and oppression isn’t necessarily a “safe” thing to do, these are not sporting events or block parties. As a general rule, if and when such confrontations become necessary, the greater the injustice you’re confronting, the greater the risk. If you’re looking for risk free “riots” you should probably stay home.

    Governments have police forces who are equipped with these weapons for a reason, and they will deploy their weapons when provoked. None of these weapons are “safe” or “harmless”. Try getting punched in the gut with a riot stick sometime instead being maced or tear gassed. Ever been blasted down the street with a fire hose?

    In theory the advantage of liberal democracy is that we can control our government by peaceful means, with votes instead of revolutions. When peaceful means and elections fail, things get risky and dangerous, even for non-violent demonstrators. Nevertheless, at the end of the day, the specter of large groups of citizens willing to enter that risky arena are always the backstop of freedom.

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