Carcinogenesis 1987-12-01

Assay of 1-nitropropane, 2-nitropropane, 1-azoxypropane and 2-azoxypropane for carcinogenicity by gavage in Sprague-Dawley rats.

E S Fiala, R Czerniak, A Castonguay, C C Conaway, A Rivenson

Index: Carcinogenesis 8(12) , 1947-9, (1987)

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Abstract

1-Nitropropane (1-NP), 2-nitropropane (2-NP), 1-azoxypropane (1-AP) and 2-azoxypropane (2-AP), were assayed for carcinogenicity by gavage in male Sprague-Dawley rats. 2-NP was given at 1 mmol/kg three times per week for 16 weeks. 1-NP (1 mmol/kg), 1-AP (0.1 mmol/kg), 2-AP (0.1 mmol/kg) or Emulphor EL-620 vehicle was given three times per week for 16 weeks, and then once per week for 10 weeks. In the 2-NP treated group both benign and malignant liver tumors occurred in 100% of the animals. No treatment related tumors occurred in rats receiving 1-NP. In rats treated with 1-AP, a high incidence of skin tumors (100%), mostly keratoacanthomas, and of tumors of the nasal cavity (59%) was observed. Rats which were given 2-AP also showed an increased incidence of skin keratoacanthomas (21%), but not of other tumors. These findings (i) confirm, using the oral route of administration, the results of inhalation studies by others indicating the potent hepatocarcinogenicity of 2-NP, (ii) establish a practical model in which the mechanism of 2-NP carcinogenicity can now be more readily studied, and (iii) demonstrate that 1-AP, and probably 2-AP, like other aliphatic azoxy compounds thus far examined, are carcinogenic in rats.