Hexachloroethane (HC) smoke grenades used by DHS in Minnesota
Executive summary
Hexachloroethane (HC) smoke — a military-style obscurant that can generate zinc chloride and other toxic byproducts — was documented in use against protesters in 2020 in multiple U.S. cities, with community scientists and reporters identifying canisters labeled “HC” and measuring residues consistent with HC smoke [1] [2] [3]. Public-health agencies and toxicology reviews characterize HC smoke and its combustion products as hazardous to lungs, the central nervous system, and the environment [4] [5] [6].
1. What the public record shows about DHS and HC grenades during 2020–21
Investigations into federal deployments of force during the 2020 protests assembled photographic, chemical, and crowdsourced evidence linking spent munitions labeled “Military-Style Maximum Smoke HC” to actions by Department of Homeland Security (DHS) personnel, and researchers estimated multiple HC canisters were used in operations such as those in Portland [2] [3]. Journalists and community chemists documented canisters marked “HC,” elevated zinc and chloride in sampled areas, and reported health complaints consistent with HC-derived zinc chloride exposure [1] [2] [7].
2. Toxicology and public-health context
Federal toxicology summaries and peer-reviewed reviews describe hexachloroethane as a compound used in military smoke devices whose combustion can produce zinc chloride and other respiratory irritants; inhalation exposure can cause chemical pneumonitis and other acute and chronic harms, and HC is listed as a suspected carcinogen in some assessments [4] [5] [6]. Historical U.S. military research and later assessments warned that high concentrations of HC smoke can injure or kill unprotected individuals, and ATSDR notes routine exposure risks where HC smoke devices are used [8] [9] [4].
3. Manufacturer documentation and safety-data controversies
Commercial products marketed as “HC” smoke grenades exist and their safety data sheets list hexachloroethane and zinc oxide among components while flagging environmental hazards; reporting and advocacy groups have accused manufacturers of downplaying human-health risks and removing explicit hazard language from some product materials over time [10] [11] [3] [12]. The Union of Concerned Scientists and other watchdogs documented marketing of HC munitions to law-enforcement buyers and criticized both vendors and agencies for opaque disclosures [3].
4. Official denials and competing interpretations
DHS and Federal Protective Services publicly denied using HC in some deployments even as visual and chemical evidence accumulated, creating a contested record in which community analyses and academic estimates conflicted with agency statements [3] [1]. Independent researchers used hierarchical Bayesian models and community-collected data to estimate deployment counts and toxic loads, arguing their methods linked observed health effects to HC combustion products, while DHS avoided confirming the specific composition of munitions in public disclosures [2] [3].
5. The Minnesota question: what can and cannot be concluded from available sources
The assembled documents in this review do not provide direct, verifiable evidence that DHS deployed HC smoke grenades in Minnesota during the 2020–21 protest period; sources refer to HC deployment in other cities and to at least one historical HC exposure during a 1998 training incident in rural Minnesota, but no source here documents DHS use of HC in Minnesota in 2020 [12] [2] [1]. Reporting and toxicology sources make clear HC devices exist and have been used by U.S. agencies, and community science has identified HC-labeled canisters in protest zones elsewhere, but the record available to this analysis is limited on state- or incident-specific attribution to Minnesota [10] [2] [3].
6. Bottom line and avenues for verification
Hexachloroethane smoke grenades were documented and extensively debated in U.S. protest policing in 2020–21, with credible evidence of HC-labeled munitions and toxic residues in some locales and authoritative toxicology warnings about health harms [2] [1] [4]. However, the specific claim that DHS used HC smoke grenades in Minnesota is not confirmed by the sources provided here; verifying that claim would require location-specific evidence such as chain-of-custody photos of spent munitions in Minnesota, agency procurement or deployment logs, official admission, or targeted chemical analyses of environmental samples from Minnesota events (no source provided documents those items) [10] [3] [2].