Is Propanediol Safe?

What is Propanediol?

There are three common chemicals that have the chemical formula C3H8O2 may be referred to as propanediol:  1,3-propanediol, propane-1,1-diol, and 1,2-propanediol. 1,2-propanediol is more commonly referred to as propylene glycol. 1,3-propanediol is the most commonly used chemical that's referred to as "propanediol" and is the subject of this article. It is a clear, thick liquid used in formulas to control viscosity. 

Is it a risk?

Propanediol does not appear to pose a significant risks when used diluted in a cosmetic formula, based on current research. However, the manufacturing of propanediol does pose potential environmental and health concerns. It can be produced from acrolein, a compound found in cigarette smoke that may contribute to lung cancer. (Source) While this wouldn't pose a risk in the finished product of propanediol, there may be exposures to workers and the environment, especially if produced in countries with less-than-stringent working and environmental regulations. 

You may also see propanediol created from "natural" sources. The most widely-distributed form is made by DuPont Chemical, created from corn syrup (most likely GMO) and a genetically-modified strain of e coli bacteria. (Source)(Source)

It can also be produced from fermenting glycerol with genetically modified bacteria. (Source)

Is it an irritant?

Propanediol can be a skin allergen. (Source) If you're reacting to a deodorant with it, you may be experiencing some form of contact allergy. It's also possible that you're experiencing a friction or moisture-related issue like intertrigo or heat rash. More info here.

Bottom Line:

Propanediol as a finished ingredient doesn't pose significant health risks unless you have an allergy to the ingredient. However, when you see propanediol in a product marketed as "natural," think GMOs because it has most likely been created with either genetically-modified bacteria or from GMO corn (or both.)