[Mutagenicity of urine after ingestion of saccharin in man].

In vitro tests of mutagenicity help detect carcinogenic substances. A variation of the Ames test may be used to study the mutagenicity of urine after exposition of the organism in vivo. Saccharin is a widely used artificial sweetener excreted in the urine which can induce dose-dependent tumours of the bladder in the animal. We studied the mutagenicity of the urine of healthy volunteers after the ingestion of a single dose of saccharin. The results show a mutagenic effect related to the dose ingested in two types of Salmonella typhimurium (TA 98 and TA 38). These results are difficult to interpret as saccharin is not mutagenic in vitro alone or in the presence of control urine which eliminates a direct carcinogenic or cocarcinogenic effect; we were unable to detect impurities or metabolites. This study underlines the difficulty of prophylactic detection of chemical carcinogens.