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Is tear gas safe? Scientists don’t know.

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.

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

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.

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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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