Polyethylene Glycols (PEGs)
What It Is
Polyethylene glycols (PEGs) are a family of synthetic polymers made by linking ethylene oxide units, typically derived from petroleum feedstocks. The base polymer is commonly listed under CAS 25322-68-3, with individual PEGs numbered by approximate molecular weight, such as PEG-8 or PEG-150. On ingredient labels they may appear as PEG followed by a number, or within the names of PEG derivatives.
Common Uses
PEGs and PEG derivatives appear in laundry detergents, dishwashing liquids, surface cleaners, and many personal-care products. They serve as thickeners, solvents, humectants, emulsifiers, and components of surfactant systems. In cleaning products, they can help control viscosity and keep ingredients evenly mixed. Higher-molecular-weight PEGs are also used as bases in some ointments and cosmetics.
How It Works
PEGs are polymers built from repeating ethylene oxide units, and chain length determines whether a given PEG is a fluid, a waxy solid, or something in between. Lower-molecular-weight PEGs act as solvents and humectants, while longer chains work as thickeners or bases. In detergents and personal-care formulas, PEG-based ingredients can help dissolve, thicken, or stabilize a mixture. Related ethoxylated surfactants are made by attaching similar ethylene oxide chains to a fatty alcohol. Because ethylene oxide drives this chemistry, the same reaction that builds the molecule can leave trace byproducts behind.
Safety and Regulation
The main safety discussion around PEGs concerns 1,4-dioxane (CAS 123-91-1), a byproduct that can form during ethoxylation and remain as a trace contaminant. The International Agency for Research on Cancer classifies 1,4-dioxane as Group 2B, possibly carcinogenic to humans, and it appears on California's Proposition 65 list. New York State limits 1,4-dioxane in household cleansing and personal-care products to 1 part per million as of December 31, 2023, after an initial 2 ppm cap took effect at the end of 2022. Manufacturers can reduce residual 1,4-dioxane through methods such as vacuum stripping, which the U.S. FDA has noted for cosmetics. The Cosmetic Ingredient Review panel has also assessed PEGs used in cosmetics.
Why Natural Flower Power Does Not Use It
We do not use polyethylene glycols in our cleaning products. Our formulas are built on plant-derived surfactants and a benzisothiazolinone (BIT) preservative system, and we have made our products in-house since 2012. We include this entry because PEGs and the ethoxylation process are common questions for anyone comparing ingredient lists.
Related Ingredients
PEGs are closely related to alcohol ethoxylates and sodium laureth sulfate, which are made by similar ethoxylation chemistry. For more on the byproduct discussed here, see 1,4-dioxane.
Sources
- International Agency for Research on Cancer (IARC). "1,4-Dioxane." Monographs.
- U.S. FDA. "1,4-Dioxane in Cosmetics: A Manufacturing Byproduct." consumer information.
- New York State Department of Environmental Conservation. "1,4-Dioxane Limits for Household Cleansing, Personal Care, and Cosmetic Products." 1 ppm limit effective December 31, 2023.
- California OEHHA. "Proposition 65 List" (1,4-dioxane).
- Cosmetic Ingredient Review (CIR). "Polyethylene Glycols (PEGs)." safety assessment.
