Propylene glycol is an additive commonly used in food, cosmetic and hygiene products.  PG appears as a tasteless and odorless alcohol.  It is a controversial as it is also an ingredient in antifreeze which has led to health concerns about possible toxic effects from eating foods which contain it.  In pharmaceutical preparations, it is used as a solvent.  For cosmetics, it stabilizes products to keep them from melting in high heat or freezing at lower temperatures.