Acute toxicity of fluorocarbon-22: toxic symptoms, lethal concentration, and its fate in rabbit and mouse.

The toxicological effect of fluorocarbon-22 (FC-22, monochlorodifluoromethane) was studied using mice and rabbits. The following symptoms were observed during continuous inhalation in sequence as time proceeded: (a) reeling, (b) weakness of forelegs, (c) falling down, (d) flow of mucous fluid from mouth and nose, mydriasis, and lacrimation, (e) violent movement of body and extremities, and (f) cyanosis. The lethal concentration (LC50) for 30 min exposure in mice was 27.7% and the threshold concentration for death in rabbits was about 30%. Blood concentration of FC-22 increased rapidly to almost equilibrium state within 1 min and completely disappeared 1 hr after inhalation ceased. Blood concentration was in direct proportion to inhaled concentration. Concerning the concentration in the tissues after death following prolonged inhalation, the concentration in fat was markedly more than other tissues but when inhalation was short, the concentration in fat was far less than other tissues. The cause of death was thought to be respiratory insufficiency.