SHORT COMMUNICATION: Lack of initiating capacity of the genotoxic air pollutant 2-nitrofluorene in the mouse skin two-stage carcinogenesis system.

2-Nitrofluorene (NF) is a potent genotoxic substance found in environments where incomplete combustion takes place. NF is a mutagen and a carcinogen in animal models. NF or 7, 12-dimethylbenz[]anthracene (DMBA) was administered once topically to female SENCAR mice followed by promotion by 12--tetradecanoylphorbol-13-acetate (TPA) in two different studies. TPA (2–5 μg) was administered twice a week for 13 or 19 weeks after initiation of DMBA (5–10 μg) or NF (50–1500 μg). DMBA administration (positive control) resulted in the formation of many papillomas, which were seen from week 8–9 after initiation. The negative controls administered acetone only were free of tumours. NF administration did not result in papilloma formation, even at high initiating doses of NF combined with a dose of TPA causing a systemic toxic effect in terms of a significant reduced body weight. The mechanism behind the absence of papilloma formation after administration of genotoxic and carcinogenic NF remains to be investigated. [ABSTRACT FROM PUBLISHER]