Hall of Shame: Propylene Glycol

Our lead off Hall of Shame baddie ingredient is one that's going to sort of ease us into it.  I don't want to scare you all off SO badly right off the bat, and propylene glycol is a toxic ingredient that is a little bit "less" toxic than some others.

Propylene glycol is found in SO MANY personal care products.  Most commonly deodorant, but also hair colorants, moisturizers, anti-aging treatments, pharmaceuticals, and artificial smoke/fog, to name a few.  The Environmental Working Groups has over 5500 products listed that include propylene glycol.

What is this stuff?  Well, like any other chemical ending in "ol," it is an alcohol, which is an organic compound (a molecule containing carbon, not a large farm with a bunch of compost piles) that contains a "hydroxyl functional group" (an oxygen atom bound to a hydrogen atom, or -OH).  Aren't you glad you skipped organic chemistry?  It is used a humectant, meaning that it draws moisture to itself, and thus whatever surface it is applied to.  It is also known as a "penetration enhancer," and not in a good way!  This is where propylene glycol's safety rating on the Skin Deep Database gets a little confusing...in and of itself, it's really not that bad, so it gets a 3.  But it paves the way for other chemicals to more easily get through your skin's barrier and into your bloodstream.  It's the gateway drug of cosmetic ingredients, if you will.

Propylene glycol isn't going to give you cancer (that we know of).  It's direct safety issues are pretty minimal, and are mostly related to being an irritant, but it can also cause some internal organ problems with your kidneys or liver (the organs that clean and filter your insides).  Some people are allergic to it.  The question arises when wondering what else it is letting into your system. 

There are many scholarly articles online about propylene glycol and its safety.  Unfortunately, most of them are .pdf links and are therefore difficult for me to link you to, but I've gone ahead and done the search for you here.

Oh, one other use of propylene glycol is as a viscosity stabilizer.  It keeps products a constant viscosity at a wide range of temperatures.  This property also comes in handy in it's main non-cosmetic use--a "less toxic" form of antifreeze.  Food for thought.

Non-toxic alternative ingredients to propylene glycol range far and wide.  This is because of the many different uses.  For example, if propylene glycol is used as a solid deodorant base, one might look for a roll-on that does not require a solid base.  If it is used as an emollient, you might see jojoba oil, almond oil, or glycerin instead.  Having said that, the average consumer is probably not likely to know what purpose the inclusion of propylene glycol in a product's formulation serves.  I say, just avoid the stuff entirely and cross it off your list of things to worry about!