What it is
A cyclic ether used as an industrial solvent and an unintentional contaminant of ethoxylated ingredients.
What it does
Not added intentionally to cosmetics; formed as a byproduct of ethoxylation used to make PEGs, polysorbates, and laureth surfactants.
Why it’s a concern
Classified by US EPA as a likely human carcinogen and by IARC as Group 2B. Never declared on ingredient lists because it is a contaminant. New York state has required finished personal care products to contain no more than 2 ppm 1,4-dioxane as of 2023. Persistent in groundwater and drinking water.
Also known as
diethylene dioxidediethylene ether
CAS numbers
123-91-1
Commonly found in
shampoobody washliquid laundry detergentdish soap
Safer alternatives
- non-ethoxylated surfactants
- products tested to NY 2 ppm cap
Related chemical families
Sources
- US EPA IRIS 1,4-Dioxane
- IARC Volume 71