Possible role of 6‐hydroxymethylbenzo[a]pyrene as a proximate carcinogen of benzo[a]pyrene and 6‐methylbenzo[a]pyrene

Benzo[a]pyrene (B[a]P) and 6‐methylbenzo[a]pyrene ( 6‐MeB[a]P) are metabolized by fortified rat‐liver homogenates to a number of metabolites including one which is indistinguishable from 6‐hydroxymethylbenzo[a]pyrene (6–OHMeB[a]P) by either thin‐layer chromatography or ultra‐violet absorption spectra. This compound is a potent carcinogen when administered by subcutaneous injection to rats. These observations are in accord with the hypothesis that methylation or hydroxymethylation is one of the first steps in metabolic activation of carcinogenic polycyclic hydrocarbons.