Butylated Hydroxytoluene E321
synthetic — Primarily synthetic.
2,6-Di-tert-butyl-4-methylphenol
CAS: 128-37-0
Factual Regulatory Reference
This database provides factual regulatory information compiled from official government sources. It does not constitute medical, nutritional, or safety advice. Regulatory status varies by country and is subject to change. Always refer to your local regulatory authority for the most current information.
What Is Butylated Hydroxytoluene?
Butylated hydroxytoluene (BHT, E321) is a synthetic phenolic antioxidant produced by alkylating p-cresol with isobutylene in the presence of an acid catalyst; it inhibits oxidation in fats and oils, preventing rancidity, and has no natural equivalent. It is used in vegetable oils, butter, breakfast cereals, snack foods, chewing gum, and dehydrated products, and has extensive non-food applications including jet fuels, rubber, and transformer oil. BHT is approved by the FDA (GRAS, 21 CFR 172.115), EFSA (ADI of 0.25 mg/kg body weight per day, 2012), JECFA (2020), Health Canada, and FSANZ; its regulatory controversy stems from conflicting animal study data where BHT has shown both tumor-promoting and tumor-inhibiting effects depending on dose, target organ, and experimental timing, making risk characterization unusually complex.
? Did You Know?
Beyond food, Butylated Hydroxytoluene is also used in cosmetics, medicine, industrial applications, household products. Its versatility makes it one of the most multi-purpose chemical compounds in everyday life.
Regulatory Analysis
BHT confounds simple risk categorization because the same body of research that raises carcinogenicity concerns in some experimental models also shows anti-tumor and antiviral properties in others, depending on dose, timing, and target organ. This dual biological profile -- where a substance appears to both promote and inhibit carcinogenesis depending on experimental design -- challenges the binary approve/ban framework that underlies most food additive regulation. The compound's very low ADI of 0.25 mg/kg reflects regulatory caution about the unresolved mechanistic picture, while its continued widespread use in food packaging materials (where it migrates into food at low levels) creates an exposure pathway that falls outside direct food additive controls.
Detailed Regulatory Assessment
European Union (EFSA)
Restricted use; maximum levels typically 100-200 mg/kg
United States (FDA)
Limited to specified levels in specific foods
Japan (MHLW)
Compliant with Japanese food sanitation law.
Acceptable Daily Intake (ADI)
International Standard (JECFA)
mg/kg body weight per day
European Standard (EFSA)
Natural Occurrence
This additive is not known to occur naturally in significant quantities.
Manufacturing
Synthesized by alkylation of p-cresol with isobutylene in the presence of an acid catalyst.
Applications Beyond Food
Widely used in lipsticks, moisturizers, and other cosmetics as an antioxidant.
Used in pharmaceutical preparations to prevent oxidation.
Used in jet fuels, rubber, petroleum products, and electrical transformer oil.
Found in food packaging materials and some household products