1,4-Dioxane

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.