What Is Propylene Glycol?
Propylene glycol is an ingredient used in skincare and cosmetics to help improve the texture and stability of formulations as well as provide the skin with water, giving your skin that glowy, dewy look.
Propylene glycol is part of a class of ingredients called glycols. Glycols have a bit of a bad reputation in the beauty industry due to a misunderstanding around how they are made and derived. Propylene glycols derived from petroleum, while this may sound scary the origin of the ingredient doesn’t indicate whether it is safe or toxic. The purification process is highly regulated and made to ensure a safe ingredient.
Propylene glycol is found in a multitude of products including toothpaste, face masks, shampoos, serums and moisturizers.
the good: Propylene glycol helps to stabilize and thicken products. It may also have moisturizing properties that can give the skin a hydrated appearance.
the not so good: It can irritate the eyes at high concentrations and when there is significant contact with the eyes. It can also cause mild irritation to the skin in people who are sensitive to propylene glycol; however, this reaction is rare.
Who is it for? All skin types except those that have an identified allergy to it.
Synergetic ingredients: Works well with most ingredients but especially with fatty oils such as coconut oil and jojoba oil.
Keep an eye on: Keep an eye out for some of the other names that propylene glycol goes by such as propanediol.
Why Is Propylene Glycol Used?
Propylene glycol is used mainly to help improve the texture and feel of products but also helps to improve the water content of the skin.
Propylene glycol is a solvent which means that it helps to dissolve ingredients that aren’t easily dissolved in water-based formulations. This helps to improve the evenness of the ingredients throughout the product so that you are receiving the benefits of the product every time you use it.
Propylene glycol is also a mild antimicrobial ingredient. This means that it helps to prevent the growth of bacteria and moulds in the product, acting as a mild preservative. Preservatives are an integral part of the formulation process as they ensure that the product is safe to use and won’t be affected by user contamination or exposure to the air. When propylene glycol is added to a product, less other preservatives are needed in order to ensure the product’s safety due to this added antimicrobial benefit.
Propylene glycol is often used to help improve the water content of the skin. This is because propylene glycol is a humectant moisturizer which means that it helps your skin to retain moisture.
Is Propylene Glycol Safe?
Propylene glycol is safe for its approved uses in cosmetics and skincare. The Cosmetic Ingredient Review Expert Panel, a group responsible for evaluating the safety and efficacy of skincare and cosmetic ingredients has reviewed propylene glycol. In their review, the Expert Panel determined that propylene glycol is safe when used under the current guidelines and for the currently approved uses. It has not shown any evidence to suggest that it produces reproductive issues, cancer, toxicity, or cumulative toxicity.
Propylene glycol is not considered to be a skin irritant, so it does not cause any irritation to the skin. Occasionally people will be sensitive to propylene glycol, and this can result in irritation. However, butylene glycol itself is non-irritating.
There is a lot of controversy around this ingredient, with many in the green beauty world claiming this ingredient is not safe for use for several reasons. One of the reasons relates to the synthetic production of propylene glycol and its derivation from petroleum. It is often a misconception, particularly in the beauty industry that where something comes from tells you about its toxicity. This is not the case. Butylene glycol has been tested for safety and doesn’t have any cumulative toxicity and is safe for its indicated uses.
Another concern that is often brought up is that propylene glycol is used in antifreeze. Propylene glycol can help to lower the freezing point of water and is used in antifreeze for this reason. However, it is another ingredient that is responsible for the classification of antifreeze as dangerous, ethylene glycol. While these two ingredients have similar names, the structure of a compound creates significant differences in function.
Another concern that often comes up in safety assessments of many skincare ingredients is the sensitivity that occurs in the manufacturing process. The manufacturing process works with high concentrations of ingredients. Sometimes these high concentrations can cause irritation and sensitivity, and manufacturing safety guidelines reflect this. It is important to keep in mind that this is not necessarily something that would be experienced at the low concentrations present in skincare products. Manufacturing guidelines are incredibly cautious as they are liable for the safety and health of their staff.
References:Thelma G. Warshaw, Franz Herrmann,Studies of Skin Reactions to Propylene Glycol1, Journal of Investigative Dermatology, Volume 19, Issue 6, 1952, Pages 423-430.
CIR, 2012. ‘Safety Assessment of Propylene Glycol, Tripropylene Glycol, and PPGs as Used in Cosmetics’, Cosmetic Ingredient Review Expert Panel.