Estimating Federal Agents’ Deployment of Lethal Zinc Chloride Gas in Portland OR Using a Bayesian Hierarchical Model

Law enforcement’s use of chemical weapons is a threat to human and environmental health, exemplified during 2020 Black Lives Matter protests in Portland, OR, where city, county, state, and federal agencies have deployed various chemicals for over 100 days. In July, US Department of Homeland Security (DHS) agents used an exceptionally toxic and unknown weapon to quell free speech in support of Black lives and against federal presence. With significant support from the community, I combined first-hand accounts, print media, videos and photos of munitions, primary literature, and analytical chemistry to identify the weapon as gaseous Zinc Chloride (ZnCl2) from Hexachloroethane (HC) “smoke” grenades. I used hierarchical Bayesian methods to estimate that DHS deployed 26 (25 – 30; 95% CI) HC grenades in July, which, given the toxicity of ZnCl2, was enough to kill 235 (156 – 306) people. Although no fatalities were associated with this ZnCl2 release, it led to acute, delayed, and persistent health issues in the exposed population, including bystanders. Given alignment of novel mass symptoms with prior case histories, however, ZnCl2 is certainly the causal agent. ZnCl2 also significantly defoliated trees whose canopies cover the deployment zone, as expected from prior research. Elevated Zn levels were also detected in stormwater samples, threatening the Willamette River ecosystem. DHS’s wanton use of ZnCl2 against protesters has created a human and environmental health crisis that extended well beyond the protests’ footprint in downtown Portland and will have lasting impacts for decades

salvage: tools for the California Delta Fish Salvage Database

Tools for interacting with the publicly available California Delta Fish Salvage Database, including continuous deployment of data access, analysis, and presentation

salvage: tools for the California Delta Fish Salvage Database

Tools for interacting with the publicly available California Delta Fish Salvage Database, including continuous deployment of data access, analysis, and presentation

salvage: tools for the California Delta Fish Salvage Database

Tools for interacting with the publicly available California Delta Fish Salvage Database, including continuous deployment of data access, analysis, and presentation

salvage: tools for the California Delta Fish Salvage Database

Tools for interacting with the publicly available California Delta Fish Salvage Database, including continuous deployment of data access, analysis, and presentation

salvage: tools for the California Delta Fish Salvage Database

Tools for interacting with the publicly available California Delta Fish Salvage Database, including continuous deployment of data access, analysis, and presentation

salvage: tools for the California Delta Fish Salvage Database

Tools for interacting with the publicly available California Delta Fish Salvage Database, including continuous deployment of data access, analysis, and presentation

salvage: tools for the California Delta Fish Salvage Database

Tools for interacting with the publicly available California Delta Fish Salvage Database, including continuous deployment of data access, analysis, and presentation

salvage: tools for the California Delta Fish Salvage Database

Tools for interacting with the publicly available California Delta Fish Salvage Database, including continuous deployment of data access, analysis, and presentation

salvage: tools for the California Delta Fish Salvage Database

Tools for interacting with the publicly available California Delta Fish Salvage Database, including continuous deployment of data access, analysis, and presentation