Polyethylene glycol (PEG) or in solution Polyethylene oxide are simple polymers with OH group at the end. In Skincare products, we can see the OH group or Alcohol are products that are for moisturizing and are referred to as humectants. These chemicals are non-toxic and considered safe for skin. Most cosmetic lines use PEG/PEO in their products because it is relatively inexpensive. But what exactly do PEG and other glycol derivatives to our skin?

So PEG and Butylene glycol at low molecular weights (meaning short chains) are used in skincare as skin hydration. These products are small enough to penetrate your pores and allow other products to travel deep into your skin as well. For someone with clogged pores or dry skin seeing PEg or Butylene glycol on an ingredients list is a good thing! However, there can be flaws when it comes to PEG and Butylene is large amounts it is possible for these chemicals to have impurities definitely when they are not purchased from a reputable source. These impurities can include ethylene oxide and 1,4 dioxane. PEG is made from a reaction between ethylene glycol and ethylene oxide while Butylene glycol is made from a reaction with PEG and ethylene oxide. According to the CDC, ethylene oxide is flammable and explosive gas. So does that mean that you should throw out all your products with PEG?

What do Scientist Say?

Here is the reaction Mechanism for PEG using ethylene oxide

Nope. PEG and Butylene glycol is often made during a step-growth reaction. Meaning that ethylene oxide is broken down to grow the polymer chain.  During the polymerization of PEG or Butylene glycol with ethylene oxide is combined with ethene glycol to produce PEG. Meaning that there is no ethylene oxide present in the PEG solution. Ethylene glycol is a very sterically hindered molecule making it very unstable long term so if there is any present it will degrade immediately.  Why is this important? Because online you can find so many articles on PEG, and Butylene Glycol. Many contradictory statements have been made about PEG. As a result, many consumers fear PEG and Butylene glycol resulting in many consumers throw out the baby with the bath water. If you don’t believe me believe the exert taken from  Steven T. Craig a Ph.D. at DABT  from Patty’s Toxicology:

“The propylene glycol ethers (PGEs), even at much higher exposure levels, do not cause the types of toxicity produced by certain of the ethylene glycol ethers (EGEs). Specifically, they do not cause damage to the thymus, testes, kidneys, blood, and blood-forming tissues as seen with ethylene glycol methyl and ethyl ether.”

What are the Cons when using PEG and Butlyene Glycol?

Many people say that you can’t trust PEG and other Glycol Ethers because on the Material Safety Data Sheet (MSDS) of Polyethylene glycol is said to be a strong skin irritant. Which is true. In high concentrations in any skincare product PEG (it can range from 200 to 700 with the most common being 400) can irritate your skin especially if you have sensitive skin and the product does not also include any other moisturizing agents.  Now there have been several studies showing that allergic reactions to PEG for people with sensitive skin and or eczema. These studies were conducted with concentrations of 50% or more. In those cases, I would avoid PEG all together. However, there have no results showing that Butylene glycol can have the same effects. Butylene glycol is shown to be less of an irritant that PEg at high concentrations but you will never see either in any product over 15%-20%.

Other Benefits?

Other than PEG and Butylene Glycol being humectants that moisturize your skin and allow other products to penetrate your skin cleaning out clogged pores they also help in producing good products. PEG and Butylene glycol dissolve in water, alcohols, acids, and oils. Making them great for mixing oil products with water based products giving you a product that does not separate. Other than that PEG and Butylene glycol hold moisture so well that they can work as preservative to limit bacteria from getting into and ruining your products.

My advice:

In terms of toxicology, you have nothing to worry about when it comes to PEG and Butylene glycol. If you have sensitive skin and the product contains a large amount of PEG, butylene glycol (First 3 ingredients) then you should probably stay away from it because it could irritate your skin. But PEG and Butylene glycol are humectants that help other products in your skincare penetrate your skin better. I can’t see why you don’t want it in your products!

Source:

American Chemical Society, Chemical Reviews, Polymerization of Ethylene Oxide, Propylene Oxide, and Other Alkylene Oxides: Synthesis, Novel Polymer Architectures, and Bioconjugation

DOI: 10.1021/acs.chemrev.5b00441 Chem. Rev. 2016, 116, 2170−2243

Patty’s Toxicology- reference for toxicological information on a large number of industrial chemicals that pose potential health hazards.

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