Benzethonium Chloride and Methylbenzethonium Chloride are quaternary ammonium salts used in cosmetics primarily as preservatives and secondarily as cationic surfactants, usually at concentrations below 1 percent. They can be irritating to the skin at concentrations of greater than 5 percent. Chronic and subchronic feeding studies indicated little or no toxic effects for both ingredients. Benzethonium Chloride was nonmutagenic in microbial systems and shown to be noncarcinogenic in rodent studies. In clinical studies, Benzethonium Chloride produced mild skin irritation at 5 percent but not at lower concentration. Neither ingredient is considered to be a sensitizer. It is concluded that both compounds are safe at concentrations of 0.5 percent in cosmetics applied to the skin. A maximum concentration of 0.02 percent is safe for cosmetics used in the eye area.