Police and tear gas: what do we really know about the chemicals being unleashed on protestors in America?
Abe Doroshow ‘21

“Can you send your request via your college email so I can verify your identity?  Because obviously we’ve got all these rioters out there trying to counter everything we do, so we wouldn’t want this information getting out.”

The date was June 15th, 2020, and the man on the phone was a commanding officer at the Wichita/Sedgwick County Law Enforcement Training Center.  Like dozens of other American cities, Wichita had seen its streets filled with clouds of chemical “riot control agents” as police clashed with Black Lives Matter protestors in the wake of George Floyd’s murder.  I had contacted the Wichita Police Department to find out which chemical agents they were authorized to use.

I sent my request via email later that day.  The officer thanked me for my inquiry, and I never heard from him again.

Riot control agents such as tear gas, pepper spray, and smoke grenades are available in a variety of chemical irritant formulations, all of which seek to incapacitate their human targets by inflicting maximum short-term pain and disorientation.  Because their intended effects—irritation of the skin, eyes, and/or respiratory system—generally wear off 20 minutes or so after exposure, chemical irritants are considered “less-lethal” or “intermediate” weapons.  Their long-term effects on human health, however, are less clear and may depend on the specific chemicals used.  Numerous studies have associated repeated exposure to 2-chlorobenzalmalononitrile (CS) and chloroacetophenone (CN), the two most common tear gas agents, with permanent blindness, miscarriages, and reduced long-term respiratory function.  Between 1993 and 1995, the ACLU of Southern California reported at least 26 fatalities among Californians exposed to oleoresin capsicum (OC), the active ingredient in pepper spray. Hexachloroethane (HC), often used in smoke grenades, is “reasonably anticipated to be a human carcinogen” by the NIH.

Chemical munitions are prohibited in warfare by the United Nations but are permitted for use by domestic law enforcement.  American law enforcement has a long history of deploying them in response to public unrest, especially during anti-racist movements.  Yet policymakers seem to know very little about them, as evidenced by the June 7th CBS interview in which Attorney General Bill Barr claimed that pepper spray was “not a chemical irritant” because “it’s not chemical.”  Although Barr was ridiculed by Science Twitter (after all, everything is chemicals), his comments stuck with me.  As an undergraduate chemistry major, I wondered: what, exactly, are these “chemical agents” that police are spraying at civilians?  Do the police themselves know?  Why should we care?

Over the next seven weeks, I investigated the chemical munitions policies of 157 metropolitan, county, and state police departments.  Fewer than half responded to my inquiries.  Some departments refused to comment altogether, citing safety or confidentiality concerns, and others referred me to policy manuals containing outdated, incomplete, or incorrect information.  A few told me they could not find any records on their chemical agents.  I had initially hoped to turn my research into a database for protestors across the US; this project proved futile.  A given protest locale could be patrolled by any combination of private, metropolitan, county, state, and federal law enforcement agencies, each with their own armory and policies.  Only some police would disclose what they used; therefore, protestors would be better off assuming they could encounter any riot control agent on the market.
 
Even when I surveyed the less-lethal weapons market, I found few answers.  Browsing the websites of private suppliers like Defense Technology, Sabre, or Combined Systems was like online shopping at a department store.  Spede-Heat, Triple Phaser, Skat Shell, Deep Freeze.  Hundreds of trademarked “less-lethal” products, each with their own proprietary cocktail of irritants, solvents, propellants and explosives.  Of the ten major manufacturers I explored in my research, only six offered online databases of their OSHA-mandated Safety Data Sheets (SDS), which listed the hazardous compounds in each product.  The rest released their SDS to buyers, in this case law enforcement—who, as I had learned, were not always willing to share them with the public.

OSHA’s SDS mandate is designed to keep workers safe while handling toxic chemicals.  The primary victims of riot control agents, however, are not the gas-masked SWAT officers who deploy them but the protestors and bystanders who are forced to inhale.  As such, complete transparency on chemical munitions is a public safety concern.  Broad terms like “smoke” and “tear gas” can obscure important differences between chemical agents, both in policy and popular discourse.  Many of the law enforcement weapons manuals I encountered did not distinguish between HC smoke grenades and their safer non-HC equivalents.  Similarly, I have seen several news articles use “tear gas” and “CS” interchangeably, with CN—a more toxic tearing agent—described as obsolete in the United States or not mentioned at all.  Yet when I began collecting data, I discovered that at least ten US police departments stock CN munitions1,  with many more unknowns.

Some cities and states explicitly ban CN and other more-toxic chemical agents, but these regulations tend to classify riot control products only by their “active” irritants.  Propellants, solvents, and explosives, even the seemingly harmless ones, may pose additional risks to people with pre-existing conditions.  Take Defense Technology’s OC Pepper Fog, a vaporizable pepper spray solution whose main solvent is soybean oil, a common allergen.  Although not all police use this specific product, pepper spray munitions are nearly ubiquitous among US law enforcement because OC is considered a lower-risk irritant.  Releasing soybean oil into city streets could send a vulnerable civilian into anaphylactic shock.  How can policymakers hope to regulate chemical munitions without a complete understanding of their varied dangers?

This summer’s Black Lives Matter uprisings have renewed calls for a nationwide ban on tear gas.  The pandemic lends additional urgency to these calls, since COVID-19 and tear gas both target the respiratory system.  Of course, not everyone is convinced.  Many believe that chemical agents, despite their risks, are preferable to other forms of crowd control used by police—namely, impact weapons like batons and rubber bullets.  Before we can have that debate, though, we need all the facts at our disposal.  And to the law enforcement agencies who claimed, like the Charlotte-Mecklenburg Police, that disclosing the chemical agents they used “would put the community and officers at risk,” rest assured: there’s no magic cure for tear gas.  Regardless of the irritant, water and dilute soap are the best acute treatments for contamination with any chemical riot control agent.  Transparency on your chemical munitions will not reduce their efficacy; it could, however, prevent needless risk to the citizens you are sworn to protect and serve.
 

1. According to my research, the following metropolitan police departments authorize the use of CN: Columbus, OH; Newark, NJ; Baltimore, MD; Iowa City, IA; Atlanta, GA; Denver, CO; Santa Rosa, CA; Phoenix, AZ; and Mobile, AL.  Additionally, CN munitions are employed by the New Mexico State Police.