Ethylene Oxide

Ethylene oxide is a small, highly reactive epoxide gas used in industrial chemistry to manufacture ethoxylated surfactants (the "PEG-" prefix on cosmetic ingredient labels) and to sterilize medical equipment. It is a confirmed human carcinogen (IARC Group 1, NTP Known) and is listed on California's Proposition 65 list for cancer and reproductive harm. In auto detailing products, ethylene oxide is rarely an intentional ingredient. It typically appears as a trace residual at parts-per-million levels in formulations that use ethoxylated surfactants or emulsifiers — the residual cannot be fully removed during manufacturing. California's Prop 65 has no exemption threshold for residual EO, so any detectable presence triggers the warning label. The presence of a Prop 65 warning for ethylene oxide on a finished product does not mean the product is unsafe in normal consumer use, but it is a legitimate disclosure for an IARC Group 1 carcinogen and the relevant regulatory translation is the −1.5 health-score deduction the rubric applies to all Prop 65 warnings.