Dermal toxicity of ammonium perfluorooctanoate

Ammonium perfluorooctanoate (CAS Registry No. 3825-26-2) is used commercially in the aqueous polymerization of fluorinated monomers. Because the chemical exists as a fine white powder which can come in contact with skin, its dermal toxicology was studied in rabbits and rats. Dermal applications of 0.5 g for 24 hr produced mild irritation to rabbit skin. The dermal LD50 was 4300 mg/kg for rabbits, 7000 mg/kg for male rats, and greater than 7500 mg/kg for female rats. Rat skin showed less irritation than rabbit skin and the general effects were more pronounced for the male (compared to the female) rat. Subchronic dermal treatment (10 applications, 5 doses, 2 rest days, 5 doses) with either 0, 20, 200, or 2000 mg/kg resulted in no, no, mild, or marked decreases in body weights, respectively. Increases in serum enzyme activities indicating hepatic effects occurred in treated rats. Liver weights were increased and necrosis and enlargement of hepatocytes were microscopically observed. Rats in the 2000 mg/kg-dose group also had epidermal necrosis at the application site. Blood organofluorine amounts were increased in a dose-related manner. All of the treatment-related toxicity findings resolved during a 42-day recovery period although prior exposure was evident by the presence of organofluorine in the blood.