Urinary excretion of mutagens in cirrhosis: limited evidence of an association.

Although bacterial mutagenesis assays have detected mutagenic substances in urine from smokers and patients treated with certain medications, these assays have not found mutagens in body fluids of subjects without such exposures. A recent report, however, suggested that mutagenic substances were present in the urine of unexposed individuals with cirrhosis. Since this observation could have important implications for the metabolism of potentially toxic substances and might provide leads to the cause of the high incidence of hepatoma among patients with cirrhosis, the reproduction of those findings of that report was attempted. In contrast with the earlier report, no evidence of mutagenic substances in urine samples from unexposed patients with cirrhosis was observed. While differences between these studies might be attributed to the subjects tested, it seems possible that the mutagenic activity reported previously was due to technical interference with the testing procedure by nonmutagenic materials in urine rather than the presence of mutagens. These observations may help clarify the interpretation of assays for urine mutagenicity in occupational or other environmental studies.