Final report on the safety assessment of PPG-11 and PPG-15 stearyl ethers

The Polypropylene Glycol (PPG) Stearyl Ethers are polypropylene ethers of stearyl ether that function as skin-conditioning agent in cosmetic formulations. Few data on the PPG Stearyl Ethers were available. Data on chemically related PPG Butyl Ethers were reviewed as a further basis for the assessment of safety. The amounts of PPG Butyl Ethers absorbed from the digestive tract were inversely proportional to the molecular weights on the compounds; skin penetration was slow to nil. During metabolism, the butyl group was removed and oxidized, and the chains were fragmented, oxidized to weak acids, and eliminated in the urine. Little acute oral toxicity was seen in animal studies. In general, the PPG Butyl Ethers were very toxic by the intravenous route and were slightly toxic to nontoxic by the intraperitoneal and subcutaneous routes. The smaller molecular weight ethers were generally more toxic than the larger molecular weight ethers. PPG-2 Butyl Ether vapor was nontoxic by the inhalation route. Undiluted PPG-15 Stearyl Ether was practically nonirritating to the eyes of rabbits, and PPG Butyl Ethers had minor to moderate conjunctival irritation, opacity, and iritis. PPG-15 Stearyl Ether was slightly irritating to rabbit skin. PPG-2 Butyl Ether caused minor, transient erythema and desquamation during a 4-hour occlusive patch test. PPG-2 Butyl Ether did not irritate the skin of pregnant mice, was nontoxic to dams, and was not teratogenic. PPG-9-13 Butyl Ether was noncarcinogenic when fed to rats. PPG-40 Butyl Ether was nonsensitizing in clinical tests. These data were considered by the Cosmetic Ingredient Review Expert Panel to support the safety of PPG Stearyl Ethers at their current use concentrations (2% to 10%, but not greater than 25%). Data on the component ingredients, Propylene Glycol, PPG, and Steraryl Alcohol, from previous cosmetic ingredient safety assessments were also considered and found to support the safety of PPG Stearyl Ethers.