Dibenz [aj] acridine (1) is a polycyclic azaaromatic hydrocarbon found in tobacco smoke condensate'and urban atmosphere2 and possesses carcinogenic proper tie^.^ It is expected, by analogy with other polycyclic hydrocarbon~,~ that the biological activation of 1 proceeds through dihydro diols and diol epoxides, and metabolism in vitro with liver microsomes from 3-methylcholanthrene pretreated animals has demonstrated the ...