ultraviolet-techno-ecology:

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.”