Final Report on the Safety Assessment of Propylene Glycol and Polypropylene Glycols

Abstract

Propylene Glycol is an aliphatic alcohol manufactured as a reaction product of propylene oxide and water. Polypropylene Glycol is a polymer formed by adding propylene oxide to dipropylene glycol. Propylene Glycol is reportedly used as a skin-conditioning agent-humectant, solvent, viscosity-decreasing agent, and humectant in thousands of cosmetic formulations. Polypropylene Glycols of various polymer lengths are reportedly used as miscellaneous skin-conditioning agents in far fewer formulations. Acute, subchronic, and short-term animal studies suggested little toxicity beyond slight growth and body weight decreases. Little ocular or skin irritation was observed in animal studies, and no sensitization was seen. Small increases in fetal malformations were seen in mice injected subcutaneously with Propylene Glycol, but a continuous breeding reproduction study in mice showed no reproductive toxicity following oral administration. A wide range of mutagenesis assays were negative, and studies in mice and rats showed no evidence of carcinogenesis. Clinical data showed skin irritation and sensitization reactions in Propylene Glycol in normal subjects at concentrations as low as 10% under occlusive conditions and dermatitis patients at concentrations as low as 2%. A careful evaluation of skin irritation and sensitization data as a function of disease state of the individual, occlusion, and concentration was done. On the basis of that analysis, it is concluded that Propylene Glycol and Polypropylene Glycol are safe for use in cosmetic products at concentrations up to 50%.