The Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food (AFC) has been asked to advise on the safety in use of TBHQ (tertiary-butylhydroquinone) in fats and oils used for human consumption. TBHQ is intended to be used at a level of up to 200 mg/kg fat or oil.
TBHQ has already been evaluated by the former Scientific Committee on Food (SCF) which concluded in 1987 that there was still a need for additional data. The SCF requested an adequate carcinogenicity study and an in vivo mutagenicity study of germ cell effects. At that time, the SCF was of the opinion that TBHQ was not acceptable for use as an antioxidant to food and did not establish an acceptable daily intake (ADI). Since then additional data on carcinogenicity and mutagenicity have become available.
Based on the data reviewed the Panel concluded that TBHQ is not carcinogenic and that further genotoxicity studies were unnecessary. The Panel considers the dog as the most sensitive species and allocated an ADI of 0-0.7 mg/kg bw based on a no-observed-adverse-effect-level (NOAEL) of 72 mg/kg bw per day in dogs to which a 100-fold safety factor was applied.
Considering that not all fat intake in high fat eaters will come from refined oils, conservative intake estimates suggest that exposure in adults and children who are high fat eaters would not exceed the ADI. However, if TBHQ were allowed to be used in infant formulae and follow on formulae at the maximum amount requested, exposure in infants and children would exceed the ADI.
The formation of 2-tertiary-butyl-p-benzoquinone (TBBQ) is likely to be due to the antioxidant action of TBHQ and this compound would probably be reduced back to TBHQ to a certain extent when ingested. The formation of TBBQ from the use of TBHQ in food is not considered to be a matter of concern