Mutagenicity and tumor initiating activity of methylated benzo[k] fluoranthenes

The mutagenic activities toward Salmonella typhimurium TA100 and tumor initiating activities on mouse skin of the polynuclear aromatic hydrocarbons benzo[k]fluoranthene (BkF),2-methylBkF,8-methylBkF,9-methyl-BkF and 7,12-dimethylBkF were compared. BkF and 2-methylBkF were the most mutagenic of the compounds tested and had comparable activity; they were more active than 7,12-dimethylBkF. 8-MethylBkF and 9-methylBkF were not mutagenic. BkF and the methylated BkFs had similar tumor initiating activities on mouse skin. The results suggest that 8,9-dihydro-8,9-epoxy-BkF might be involved in the metabolic activation of BkF to a mutagen, but do not indicate which metabolite may be involved in BkF tumorigenesis.