Urothelial damage and tumor initiation by urinary metabolites of sodium o-phenylphenate in the urinary bladder of female rats.

Intravesical instillation of 2-phenyl-1,4-benzoquinone (PBQ), a metabolite of sodium o-phenylphenate (Na-OPP), at a concentration of 0.1% in saline caused acute epithelial injury, prolonged inflammation and epithelial hyperplasia in female F344 rats. Ten such instillations of PBQ within 5 weeks resulted in the development of preneoplastic lesions of the urinary bladder epithelium when followed by 5% sodium saccharin feeding for 31 weeks. Since neither urothelial damage nor tumor-initiating activity was observed with either Na-OPP itself or another metabolite, phenylhydroquinone, PBQ may play an essential role in Na-OPP urinary bladder carcinogenesis.