Radiocarbon in 2, 4-dichlorophenyl 3'-methoxy-4'-nitro-[U-14C]phenyl ether (chlomethoxynil) orally administered to rats was rapidly and almost completely excreted into the urine and feces (13. 7 and 79. 5%, respectively) within 48 hr. Major urinary metabolites were S-(3-methoxy-4-nitrophenyl)cysteine and S-(3-methoxy-4-nitrophenyl)mercapturic acid, accounting for 3. 3 and 2. 7% of dose, respectively. A trace amount of 3-methoxy-4-nitrophenyl sulfate was also detected in the urine. 2,

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... henyl 4'-acetamido-3'-hydroxyphenyl ether was the main fecal metabolite, which was newly identified in this study, accounting for 24. 6% of dose. The finding that Chlomethoxynil easily cleaved to S-(3-methoxy-4-nitrophenyl) glutathione and 2, 4-dichlorophenol in the presence of rat liver cytosol and glutathione suggested that the major urinary metabolites were formed through the mercapturic acid pathway from S-(3-methoxy-4-nitrophenyl)glutathione.