BHT

Butylated hydroxytoluene (BHT, E321), chemically 2,6-di-tert-butyl-4-methylphenol, is a synthetic phenolic antioxidant widely used to retard oxidative rancidity in fats, oils, and fat-containing foods. It is lipophilic and highly effective in dry food systems including breakfast cereals, dehydrated potato products, chewing gum bases, and packaging materials in applications where it migrates from the packaging into the food. BHT is frequently combined with BHA in commercial antioxidant blends because of documented synergism, where the combined effect exceeds the sum of each component alone. Like BHA, BHT functions as a chain-breaking antioxidant by donating hydrogen to lipid peroxyl radicals.

JECFA established an ADI of 0.3 mg/kg body weight per day for BHT (evaluated 1997), based on liver and thyroid effects observed in long-term rodent feeding studies. The toxicological database for BHT is substantial: it has been shown to act as a co-carcinogen or tumour promoter in some rodent studies while demonstrating anticarcinogenic effects against certain chemically induced tumours in others — a pattern consistent with an antioxidant compound operating through redox-modulating pathways. IARC classified BHT as Group 3 (not classifiable as to its carcinogenicity in humans) in 1986. The European Food Safety Authority has not yet completed a current-standards systematic re-evaluation; the existing EU position relies on assessments from the Scientific Committee on Food.

BHT is authorised under EU Regulation (EC) No 1333/2008 at maximum permitted levels of 100–200 mg/kg in fat and oil-containing foods, and is GRAS in the United States under FDA 21 CFR §182.3173. It is banned as a food additive in Japan and Australia largely on precautionary grounds. Consumer pressure and clean-label trends have led many manufacturers, particularly in the cereal and snack categories, to replace BHT with mixed tocopherols, ascorbyl palmitate, or rosemary extract — a reformulation wave that accelerated noticeably after 2015 when several major US food companies announced voluntary removal from their portfolios.