Pathological analysis of the carcinogenicity of sodium o-phenylphenate and o-phenylphenol.

Potential carcinogenicity and promoting effects of sodium o-phenylphenate (OPP-Na) in two-stage urinary bladder carcinogenesis were shown in male F344 rats pretreated with 0.01% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN). However, o-phenylphenol (OPP) did not enhance the occurrence of urinary bladder lesions in rats pretreated with BBN. Scanning electron microscopy of OPP-Na-treated animals demonstrated a dose-dependent production of pleomorphic microvilli on the luminal surface of bladder superficial cells, whereas these were not observed with OPP. These results give some support to the conclusion that OPP-Na may be carcinogenic in the urinary bladder of male rats.