According to Wikipedia, "Propylene glycol is considered generally recognized as safe (GRAS) by the U.S. Food and Drug Administration, and it is used as an humec

According to Wikipedia, "Propylene glycol is considered generally recognized as safe (GRAS) by the U.S. Food and Drug Administration, and it is used as an humectant (E1520), solvent, and preservative in food ... It is also used in pharmaceutical and personal care products."