Scientists Identified a Green, Poisonous Gas Used by Federal Agents on Portland Protesters

The toxic chemical is more than an alternative type of tear gas

Photo: Nathan Howard/Stringer/Getty Images

By July, Black Lives Matter protesters in Portland had become accustomed to the gray, black, and colorless tear gas that wafted through the city streets every night. But that month, they started seeing plumes of an unusual green smoke, too. Puddles of greenish residue seeped into the city’s storm drains. Human rights advocates and conservationists called on the local government to investigate the environmental impact of these chemical weapons, which had been deployed by the police, but no new chemicals were identified to the public.

Juniper L. Simonis, PhD, a volunteer protest medic whose pronouns are they/them, scanned Portland’s storm drains for clues. Simonis, who is also a quantitative investigator with a doctorate in aquatic ecology, knew that identifying the new substance would be essential to protecting protesters and the environment from its effects. In lieu of information from the government, they hoped for harder evidence: the cast-off gas canisters, which might contain traces of the chemicals.

They didn’t expect to read the evidence right on the label. Simonis and other volunteers eventually collected dozens of canisters they traced to the new weapon. Several still bore the logo of their manufacturer, Defense Technologies, and the label “HC,” indicating that these canisters had once contained a chemical agent that was unlike anything Black Lives Matter protesters had seen in Portland or elsewhere.

After a summer of protests downtown, police and protesters had developed a sort of ritual. Every evening between late May and mid-July, as protesters gathered in the plaza in front of the Justice Center, police stood by while activists listened to speeches and led chants. If the crowd started to march through the city, the Portland Police Bureau (PPB) followed behind in armored cars and on foot. At any point, officers might fire less-lethal munitions at protesters, including tear gas, flash-bangs, and smoke grenades. At the end of each evening, a few officers picked up the bulk of the solid debris left behind by these munitions. Residue from these munitions was left untouched on the ground.

That pattern changed after President Trump’s June 26 executive order designating Operation Legend, a broad Department of Homeland Security (DHS) initiative intended to protect historical monuments from Black Lives Matter protesters. Starting on July 2, 114 federal officers, including U.S. Marshals and Immigration and Customs Enforcement (ICE) agents, arrived in Portland.

While the PPB had only launched individual tear gas canisters by hand, the new federal agents introduced new distribution systems, like thermal foggers — “Picture the backpack things from Ghostbusters 2,” says Simonis — that left very little evidence of use. Newly deputized PPB officers power-washed the steps in front of the Justice Center every night, sending untreated toxic waste into the city’s stormwater system and with it, the residues needed to identify the makeup of the tear gas.

Three days after they picked up the first canister, or skat, Simonis was tear-gassed and detained by federal agents. While they recovered from the violent arrest, reports poured in from other protest medics about activists and bystanders exhibiting strange new symptoms like vomiting and intense burning sensations on exposed skin — far outside the typical effects for tear gas and pepper spray.

Three weeks later, when Simonis was well enough to walk outside, their impromptu sample collections had blossomed into a full aquatic ecotoxicology side project, the Chemical Weapons Research Consortium (CWRC), dedicated to identifying chemical agents and documenting their use in Portland. Protesters, journalists, and other scientists helped Simonis to collect canisters and other hardware after clashes with police. In Simonis’ garage-turned-laboratory, they carefully swabbed each canister for chemical residues and compared each to known samples to identify any unusual chemicals.

To analyze the unknown chemicals, CWRC enlisted the help of a local laboratory, Specialty Analytical. The results, first published in a press release on October 10, confirmed suspicions that federal law enforcement was using a new compound on Portland protesters. Canisters collected from protest areas contained trace amounts of hexachloroethane (commonly HC), a white powder that, when heated in the presence of metal salts, reacts to form a dense cloud of green or white smoke that smells like camphor and wreaks havoc on biological systems.

“There’s no reason to have pain inflicted on you if you haven’t done anything wrong.”

HC is a highly regulated toxin, labeled as a “likely carcinogen” and skin irritant by the Environmental Protection Agency. Eye masks and gloves are recommended for people who handle the chemical. Defense Technologies, an imprint of Pennsylvania-based security equipment manufacturer Safariland, markets the HC canisters as “military-style” smokers, even though the U.S. military actually stopped using HC in grenades in the 1990s due to its extreme toxicity.

Activists are more concerned about the chemicals that leave the canister than those packed inside it. Firing an HC grenade triggers a two-stage reaction in which the chlorine in HC rapidly combines with metallic zinc, resulting in zinc chloride, a toxic metal fume that appears as a greenish-white smoke. “It’s a chemical reaction in a can,” says Simonis. “The zinc chloride is an intentional product of the grenade’s design.” The Material Safety Data Sheet supplied by Safariland, however, doesn’t mention zinc chloride at all.

Gaseous zinc chloride, also known as hexite, is more than an alternative type of tear gas. Because it contains the super-hot gaseous forms of both chloride ions and zinc, a heavy metal, hexite plumes are highly mobile and extremely dangerous to most forms of life. The chloride ions increase the uptake of zinc particles by exposed cells on the skin or mucous membranes. Zinc can accumulate in tissues and organs, then mobilize later and cause a new set of symptoms. The most striking effects of zinc chloride toxicity in the street — vomiting, burning skin, coughing — are only the first onslaught of a chronic, unpredictable respiratory condition that can cause severe liver damage, fatigue, weight loss, and anorexia, in addition to difficulty breathing.

Zinc toxicity sharply contrasts with the effects of tear gas, which tend to be excruciating but short-lived, with dangerous exceptions. “[Conventional tear gas] causes pain through a specific mechanism,” says B. Zane Horowitz, PhD, an emergency toxicologist in the Portland area and author of a recent op-ed decrying the city’s use of tear gas on protesters in the journal Toxicology Communications. Tear gas shorts the nervous system’s pain response, essentially creating the experience of pain without doing lasting damage — most of the time. Still, says Horowitz, “There’s no reason to have pain inflicted on you if you haven’t done anything wrong.”

The new chemical made it harder for medics to balance first aid during protests with social distancing. Logan Krus, a medic affiliated with the Portland-based Rosehip Medic Collective, says people tend to instinctively pull their masks off the moment they are sprayed, which makes them vulnerable to both viral transmission and surveillance cameras. If they are sprayed with conventional tear gas, the low chance of long-term damage means they can choose to bear the pain rather than risk contamination from an eye flush. “Tear gas is a horrible thing to go through, but if someone wants to wash your eyes in a non-Covid-safe way, it’s okay to refuse care,” as symptoms will eventually resolve themselves, says Krus. The long-term toxicity of zinc chloride changes that calculation.

“Before we heard about the green gas, we’d been handing out respirators to BIPoC activists on the ground because we were concerned that they were having to take off their regular masks whenever they got tear-gassed, and then that exposed them to Covid,” says Krus. Then, photos of the strange clouds surfaced. “We had a panic moment. How do we get a lot more respirators?”

Because zinc chloride moves differently than conventional tear gases, its presence is difficult to detect. This has further complicated CWRC’s efforts to bring those responsible for deploying the toxic chemical to justice.

“Now I don’t go around the feds without a gas mask.”

In September, Portland’s Bureau of Environmental Services (BES) conducted its own testing on the effects of tear gas in the stormwater system, partly in response to the demands of Portland lawmakers earlier in the summer. It tested three manholes and six storm drains near the epicenter of protest activity. “Our goal was to take a sample of the stormwater in that pipe before the first rain before it flushed into that river,” explains BES public information officer Diane Dulken. On September 10, BES announced in a press release that their surveys had found elevated levels of hexavalent chromium, lead, and other metals near the courthouse and the Justice Center, but that “contaminant levels dropped to within a normal range before reaching the Willamette River.” Portland Mayor Ted Wheeler, who had recently announced a new executive order banning tear gas use by PPB, expressed concern about the excessive use of chemical weapons on protesters but called the report “good news.” No further action has been announced to address the contamination.

Simonis argues that the BES investigation, and the conclusions Wheeler drew from it, are insufficient. “If you know how chemicals, good and bad, mobilize in aquatic systems, you don’t take samples from one point, at one time only, and make any statement about mobilization,” Simonis explains. Heavy metals tend not to flow through aquatic systems at a constant rate, instead building up in pockets in the sediment and leaching into the water from there. When that happens, says Simonis, “a low concentration downstream means nothing.”

The federal government’s refusal to cooperate with chemical weapons legislation and local lawmakers has further hampered research by CWRC and BES. Federal troops have erected an illegal barricade around the Mark O. Hatfield Courthouse and have refused to allow BES to test the storm drain inside the site, despite the city’s threat to levy a $20,000 penalty against the federal government for every day the barricade stands after September 10.

In October, a group of environmental nongovernmental organizations and nonprofits sued acting DHS Secretary Chad Wolf. They accused him and DHS of failing to conduct environmental impact studies for any of the chemical munitions used, file an emergency plan as required, and provide access to deployment data. All of these requirements are outlined in the National Environmental Policy Act (NEPA) of 1970. Without this documentation, both BES and CWRC have had to rely on volunteer information and social media to prove HC had been used at all.

The complaint also alleges that DHS agents “have misused tear gas and other munitions by aiming them directly into crowds of people and by shooting tear gas canisters directly at individuals.” DHS did not respond to a request for comment.

Krus has modified a respirator in preparation for a new wave of protests in the spring. Photo: Logan Krus

This fall, as lockdowns have tightened across the country, street protests have begun to ebb. But medics like Krus are already preparing for another wave of protest and response once the weather warms up. The risk of coronavirus transmission will likely remain a concern. Krus recently modified a Honeywell 7600 manual respirator to rely on a microphone attachment rather than a speaker port for added Covid safety, an innovation they plan to share with the wider protest community when spring arrives.

“Winter months in Portland tend to be a bit calmer,” says Krus. “Next summer, I imagine, will still be an interesting time.”

Simonis, whose investigation of the ecological effects of hexite and HC is ongoing, says the distrust of police, especially federal troops, among activists is unlikely to change soon.

“The degree to which law enforcement believes Black lives do not matter is shown by their willingness to use known toxic hazardous waste chemicals indiscriminately,” Simonis says. “Now I don’t go around the feds without a gas mask.”

Lynne Peskoe-Yang is a science and technology reporter.

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