Along with other glycols and glycerol, this is a humectant or humidifying and delivery ingredient used in cosmetics. There are websites and spam e-mails stating that propylene glycol is really industrial antifreeze and that it is the major ingredient in brake and hydraulic fluids. These sites also state that tests show it’s a strong skin sensitizer. They further point out that the Material Safety Data Sheet (MSDS) on propylene glycol warns users to avoid skin contact. As ominous as this sounds, it’s so far from the reality of cosmetics formulations that almost none of it holds any water or poses any real concern. In fact, research from toxicologists has shown that propylene glycol and similar ingredients don’t present a health risk for people when used in cosmetics. It’s important to realize that the MSDS refers to a 100% concentration of a substance. Even water and salt have frightening comments regarding their safety according to their MSDS reports. In cosmetics, propylene glycol is used only in the smallest amounts to keep products from melting in high heat or from freezing. It also helps active ingredients penetrate skin. In the minute amounts in cosmetics, it’s not a concern in the least.
The Cosmetic Ingredient Review Board and other groups have analyzed all of the toxicology data and exposure studies concerning topical application of propylene glycol as commonly used in cosmetics products. Their conclusion was that it is safe and does not pose a health risk to consumers.
References for this information:
Critical Reviews in Toxicology, April 2013, issue 4, pages 363-390
Agency for Toxic Substances and Disease Registry. Public Health Statement: Ethylene Glycol and Propylene Glycol. [Internet]. 1997 [cited 2015 July]