Promotion of 2-(ethylnitrosamino)ethanol-induced renal carcinogenesis in rats by nephrotoxic compounds: positive responses with folic acid, basic lead acetate, and N-(3,5-dichlorophenyl)succinimide but not with 2,3-dibromo-1-propanol phosphate.

The promoting effects of nephrotoxic chemicals, folic acid (FA), N-(3,5-dichlorophenyl)succinimide (NDPS), 2,3-dibromo-1-propanol phosphate (Tris-BP), and basic lead acetate (LAB), on 2-(ethylnitrosamino)ethanol (EHEN)-induced renal carcinogenesis were examined in F344 rats. The rats were treated with 0.1% EHEN in their drinking water for 1 week and then given one of the nephrotoxic chemicals for 35 weeks. FA was injected sc once a week at a dose of 300 mg/kg for the first 8 weeks and thereafter at 100 mg/kg. NDPS, Tris-BP, and LAB were mixed in the diet at concentrations of 0.5, 0.01, and 0.1%, respectively. At week 3 the right kidney was removed to enhance renal neoplasia. Renal cell tumor incidence was significantly increased by both FA and LAB and was slightly increased by NDPS, whereas Tris-BP had no effect. The data show that FA, LAB, and NDPS are promoters of EHEN-induced renal carcinogenesis.