Along with other glycols and glycerol, this is a humectant or humidifying and delivery ingredient used in cosmetics. There are Web sites 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 is a strong skin irritant. They further point out that the Material Safety Data Sheet (MSDS) on propylene glycol warns users to avoid skin contact because systemically (in the body) it can cause liver abnormalities and kidney damage. As ominous as this sounds, it is so far from the reality of cosmetic formulations that almost none of it holds any water or poses real concern.
It is important to realize that the MSDS sheets are talking about 100% concentrations of a substance. Even water and salt have frightening comments regarding their safety according to their MSDSs. In cosmetics, propylene glycol is used only in the smallest amounts to keep products from melting in high heat or freezing when it is cold. It also helps active ingredients penetrate the skin. In the minute amounts used in cosmetics, it is not a concern in the least. Women are not suffering from liver problems because of propylene glycol in cosmetics. And finally, according to the U.S. Department of Health and Human Services, within the Public Health Services Agency for Toxic Substances and Disease Registry, “studies have not shown these chemicals [propylene or the other glycols as used in cosmetics] to be carcinogens” (Source: www.atsdr.cdc.gov).
The Cosmetic Ingredent Review Board has analyzed all of the toxicology data and exposure studies concerning topical application of propylene glycol as it is commonly used in cosmetic products. Their conclusion was that it is safe as used and does not pose a health risk to consumers.