What it is
Ethoxylated ingredients, such as PEGs, polysorbates, ceteareth, sodium laureth sulfate and other ingredients containing “-eth,” are made through a manufacturing process called ethoxylation, which reacts an ingredient with ethylene oxide, mainly to make surfactants milder and better at mixing with water. Ethylene oxide is used to produce glycol ethers and nonionic surfactants, among other chemicals (IARC, 1994). Ethoxylated ingredients are common in detergents, foaming agents, emulsifiers and solvents (FDA).
Why it is a concern
- 1,4-dioxane contamination. 1,4-dioxane is not added on purpose; it forms as a byproduct when certain cosmetic ingredients are made (FDA). During ethoxylation, ethylene oxide can pair up with itself to form 1,4-dioxane (Black et al., 2001). The US National Toxicology Program considers 1,4-dioxane reasonably anticipated to be a human carcinogen based on animal studies, and the EPA classifies it as likely to be carcinogenic to humans, although human data are not adequate to confirm the link (FDA). It can penetrate animal and human skin when applied in some preparations, such as lotions, though it also evaporates readily (FDA).
- How much has been found. FDA surveys detected 1,4-dioxane in ethoxylated raw materials at up to 1,410 ppm and in finished cosmetics at up to 279 ppm (Black et al., 2001). Levels have fallen as manufacturers changed their processes: in a 2008 FDA survey, 80% of products had no detectable 1,4-dioxane and the highest level was 11.6 ppm, and in 2018 only 2 of 82 children’s products tested were above 10 ppm (FDA). For balance: an EU scientific committee concluded that 1,4-dioxane in cosmetics is safe for consumers at trace levels of 10 ppm or less (FDA). Because it is never listed on labels, though, you cannot tell how much a given product contains without testing.
- Ethylene oxide is a known carcinogen. The International Agency for Research on Cancer classifies ethylene oxide as carcinogenic to humans (Group 1) (IARC, 1994). California also lists it as causing cancer, developmental toxicity, and male and female reproductive toxicity (OEHHA, Proposition 65).
- Regulators are limiting it. New York caps 1,4-dioxane at 1 ppm in household cleaning and personal care products and 10 ppm in cosmetics, and all manufacturer waivers expired on December 30, 2025 (NY DEC). There is no federal US limit; since the 1980s, the FDA has only recommended that manufacturers use “vacuum stripping” to reduce it (FDA).
Where it can be found
Ethoxylated ingredients show up mostly in products that foam, cleanse or emulsify. New York’s law covers products such as hair shampoo, hair conditioner, soap, bath gels and other bath products, along with household cleaners like laundry and dish detergents (NY DEC). They are also used as emulsifiers in creams and lotions (FDA), and 1,4-dioxane has even been found at up to 378 ppm in food-grade polysorbates (Black et al., 2001).
Label tip
1,4-dioxane itself will never appear on a label, so look for the ingredients that can carry it. The FDA flags names containing “PEG,” “polyethylene,” “polyethylene glycol,” “polyoxyethylene,” “-eth-” or “-oxynol-” (FDA). New York adds sodium laureth sulfate and ingredients containing “xynol,” “ceteareth” and “oleth” (NY DEC). Also watch for “polysorbate” followed by a number, such as polysorbate 20 or polysorbate 80 (Black et al., 2001). Keep in mind that a product containing one of these ingredients is not necessarily contaminated; only testing can confirm it (NY DEC).
References
- US Food and Drug Administration. 1,4-Dioxane in Cosmetics: A Manufacturing Byproduct. https://www.fda.gov/cosmetics/potential-contaminants-cosmetics/14-dioxane-cosmetics-manufacturing-byproduct
- Black RE, Hurley FJ, Havery DC. Occurrence of 1,4-dioxane in cosmetic raw materials and finished cosmetic products. J AOAC Int. 2001;84(3):666–670. https://pubmed.ncbi.nlm.nih.gov/11417628/
- International Agency for Research on Cancer. Ethylene Oxide (Summary & Evaluation, Volume 60). 1994. https://inchem.org/documents/iarc/vol60/m60-02.html
- California Office of Environmental Health Hazard Assessment. Ethylene Oxide – Proposition 65. https://oehha.ca.gov/proposition-65/chemicals/ethylene-oxide
- New York State Department of Environmental Conservation. 1,4-Dioxane Limits for Household Cleansing, Personal Care, and Cosmetic Products. https://dec.ny.gov/environmental-protection/pollution-prevention/household-personal-cosmetic-dioxane-limits
- PubChem. Ethylene Oxide (CID 6354). https://pubchem.ncbi.nlm.nih.gov/compound/Ethylene-Oxide
- PubChem. 1,4-Dioxane (CID 31275). https://pubchem.ncbi.nlm.nih.gov/compound/1_4-Dioxane