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U.S. Department of Health and Human Services

Database of Select Committee on GRAS Substances (SCOGS) Reviews

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Butylated Hydroxytoluene (BHT)

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Report No.:  2
Type of Conclusion:  3
ID Code:  128-37-0
Year:  1973
CFR Section:  172.115
SCOGS Opinion:  The information on the metabolism and toxicology of BHT is extensive. There is ample evidence of efficacy of this compound as an antioxidant. It has been suggested that BHT in fatty tissue may even have some effect similar to that of vitamin E. There are some data to indicate that BHT in diets reduces the incidence of certain tumors and the rate of absorption in the rat. The available evidence does not support the view that BHT interferes in any specific way with cellular metabolism. There is no evidence that demonstrates that BHT causes frank biochemical lesions in the liver; moreover, it is obvious that high doses of BHT are needed to induce biochemical alterations. With 0.1% BHT in the diet in rats there are differening data in the literature concerning the effect of such treatment on liver growth and liver enzymes. At 0.05 % in the dit, no toxic effects are discernible. This "no-effect level" is equivalent to 50 mg per kg per day. However, BHT increases the level of microsomal enzymes in the liver. The significance of this increase raises certain questions. The liver weight of animals fed BHT is increased and some interpret this enlargement as hypertrophy which is fully reversible and without apparent toxicological significance. But a point could occur at which adaptation fails, a new condition is created, and injury commences. It does not appear that "fully adapted" livers have been challenged by additional doses of BHT or, more importantly, other chemicals. In view of the widespread use, for example, of oral contraceptives, it is felt that informatoin should be available on the effect of challenging fully adapted livers with compounds which are themselves metabolized by microsomal hydroxylases. Therefore, there is the need to determine the effects of BHT at levels now present in foods under conditions where steroid hormones or oral contraceptives are being ingested. Other tissues such as lung and the gastrointestinal mucosa, in addition to liver, can respond to enzyme inducing agents. More information is required on the inducing properties of BHT on extra hepatic organs. If induction should be found to occur, it would be necessary to determine the effect of such enzymes on the conversion of other ingeted materials into toxic substances or carcinogens. The Select Committee has weighed the foregoring and concludes that: While no evidence in the available information on BHT demonstrates a hazard to the public when it is used at levels that are now current and in the manner now practiced, uncertainties exist requiring that additional studies should be conducted.