BHT
BHT (Butylated Hydroxy Toluene) is a common synthetic antioxidant used as a preservative in cosmetic formulations. It has been used as both a food and cosmetics additive since the 1970s. It is typically used at low concentrations, usually around 0.01–0.1%, in cosmetic products. Its CAS number is 128-37-0 and its chemical/IUPAC name is 2,6-Di-Tert-Butyl-P-Cresol.
BHT functions primarily as a synthetic antioxidant and preservative, helping to protect cosmetic formulations from oxidative degradation. The CIR (Cosmetic Ingredient Review) has concluded that at the low concentrations used in cosmetics, BHT does not penetrate skin far enough to be absorbed into the bloodstream and is considered safe for cosmetic use.
There is some controversy around BHT regarding potential carcinogenicity, though studies examining this concern have focused on oral ingestion rather than topical cosmetic use. The CIR has assessed it as safe at typical cosmetic use levels (0.01–0.1%).
