Formation of mutagenic metabolites from 2-nitrofluorene in the rat

The in vivo metabolism of the air pollutant 2-nitrofluorene (NF) has been investigated in the rat. An orally administered dose of ¹⁴C-NF was excreted rapidly in the urine and feces with a ratio of approximately 2:1. A high mutagenicity followed the excreted dose both in the urine and feces. Identification of the metabolites using high pressure liquid chromatography and mass spectrometry show that the major part of the free metabolites are hydroxylated 2-acetylaminofluorenes (OH-AAF). The results of this study are in line with the contention that NF enters the metabolic pathway of the potent and well-known carcinogen 2-acetylaminofluorene (AAF). The fact that NF is established as an urban air pollutant and that it gives rise to a potent carcinogen in vivo is of considerable toxicological significance.