Recent reports have been raising concerns as to, not just the use of gas againzt protesters, but also the type. 

The Intercept recently reported that the Mayor of Portland, Ted Wheeler acknowledged that the city has used “CS” tear gas during protests for the Black Lives Matter movement. The commonly used formulation contains 2-chlorobenzalmalononitrile, a compound that was designed to induce immediate pain but can also have long-term effects, including chronic bronchitis. In early September, Wheeler ordered the police to stop using it. Tear gas is banned in war but can be used to disperse crowds of civilians.

In July it is reported that during “Operation Diligent Valor,” an operation to get the protests under control, the use of chemical irritants intensified. Among the products that federal agents appear to have used during the crackdown is a hexachloroethane “smoke grenade” manufactured by a company called Defense Technology and sold as “Maximum HC Smoke.” 

The Intercept goes on to say

"The HC smoke bomb, which was developed in the 1930s to disperse people and conceal actions on the battlefield, is particularly dangerous to health and the environment. The Military-Style Maximum Smoke HC grenade from Defense Technology is “very toxic to aquatic life with long-lasting effects” and is “suspected of causing cancer,” according to the grenade’s safety data sheet. Environmental effects of the smoke bombs include defoliation of trees and a long-term reduction in their growth.

The health effects of hexachloroethane include nausea, vomiting, central nervous system depression, and kidney and liver damage, according to the compound’s material safety data sheet. Zinc chloride, a compound released by the grenades in even greater amounts than hexachloroethane, has “long-lasting effects” on aquatic life, according to its manufacturer’s safety data sheet. The toxic compound also causes fever, chest pain, and liver damage and is associated with anorexia, fatigue, and weight loss.

Although the grenade’s manufacturer, Defense Technology, markets it as “military style,” the Department of Defense appears to have begun phasing out the smoke bomb years ago because it was incredibly dangerous. A 1994 report of the U.S. Army Biomedical Research and Development Laboratory notes, “Exposure of unprotected soldiers to high concentrations of HC smoke for even a few minutes has resulted in injuries and fatalities.”"

Yet it appears it forces continue to use these products against civillians. Both the DHS and manufacturer of the HC canisters did not respond to The Intercept's request for comments.