Comparison of the effect of butylated hydroxytoluene on N-nitrosomethylurea and 7,12-dimethylbenz[a]-anthracene-induced mammary tumors.

The antioxidant butylated hydroxytoluene (BHT) when fed at a level of 0.3% in a defined semi-purified diet was found to decrease mammary tumor incidence in female Sprague-Dawley rats induced by 7,12-dimethylbenz[a]-anthracene (DMBA). however, no effect of BHT on tumor incidence was seen in animals consuming the same diet, under identical experimental conditions, but treated with the carcinogen nitrosomethylurea (NMU). Differences in effectiveness of BHT as a tumor inhibitor in the 2 model systems, and thoughts as to a possible mechanism of action with regard to BHT are discussed.