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CarCareTruth

1,4-Dioxane

  • Other solvents
  • CAS 123-91-1
  • IUPAC: 1,4-Dioxane

1,4-Dioxane (CAS 123-91-1) appears in 7 of the 2,122 car-care products CarCareTruth tracks (as of August 2026). It is listed on California's Proposition 65.

1,4-Dioxane is classified by IARC as Group 2B (possibly carcinogenic to humans) and by the US EPA as a probable human carcinogen (Class B2). California's Prop 65 lists it as a carcinogen. It appears in car-care products only as a trace byproduct of surfactant ethoxylation, not as an intentional ingredient, and at those trace levels exposure during normal use is generally low; the GHS profile also includes H319 (eye irritation).

1,4-Dioxane is a probable human carcinogen (IARC Group 2B, EPA Class B2) found as a trace contaminant in products that use ethoxylated surfactants. It is not an intentional ingredient — it forms as a byproduct during the ethoxylation process. California Proposition 65 lists 1,4-dioxane as a known carcinogen. At trace concentrations typical in consumer detailing products, exposure risk from skin contact or inhalation during normal use is generally considered low, but the presence of a Prop 65 carcinogen triggers the required California warning label. EPA has been tightening drinking water guidance on 1,4-dioxane due to its groundwater persistence.

Health & environment profile

VOC
no
Prop 65 listed
yes
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
no
Biodegradable
no
Bioaccumulative
no
Persistent
yes
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
2/5
Purpose: Process contaminant / trace impurity — not an intentional ingredient; forms as a byproduct during ethoxylation of surfactants (e.g., sodium laureth sulfate, polyethylene glycols)

Common questions about 1,4-Dioxane

What is 1,4-Dioxane used for in car care?
Process contaminant / trace impurity — not an intentional ingredient; forms as a byproduct during ethoxylation of surfactants (e.g., sodium laureth sulfate, polyethylene glycols)
Is 1,4-Dioxane a VOC?
No. 1,4-Dioxane is not classified as a volatile organic compound (VOC).
Is 1,4-Dioxane on California's Proposition 65 list?
Yes. 1,4-Dioxane appears on California's Proposition 65 list.

7 products contain this

Related

Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.