Nature of the residue of [C-14]cloransulam-methyl in lactating goats

Two lactating goats were given a daily oral dose of either [UL-aniline-C-14 ; AN] or [triazolopyrimidine-7,9-C-14; TP]cloransulam-methyl for 5 consecut ive days. Each animal received a dietary equivalent of similar to 10 mg/kg of test material, similar to 2225 times the realistic maximum dietary expos ure for a dairy animal. Milk, urine, and feces samples were collected in th e morning and afternoon for each animal. Each goat was sacrificed within 23 h of receiving the last dose, and the liver, kidneys, samples of blood, fa t, muscle, and gastrointestinal tract contents, and urine from the bladder were collected. All of these samples were analyzed for C-14 content. Cloran sulam-methyl (CM) was rapidly excreted by the animals, with 99.9% of the re covered radioactivity appearing in the urine and feces. Radiochemical analy sis showed very low residues, with the highest being in the kidneys at 0.12 2 and 0.128 mg equiv of CM/kg (AN and TP labeled compounds, respectively). Radioactive residues were extracted and fractionated from kidney, liver, an d milk. Analysis showed similar to 0.066 mg/kg CM in the kidney but <0.003 mg/kg in the liver. Only one metabolite, cloransulam, was identified (in li ver, 9.5% of total radioactive residue: 0.005 mg/kg). All other metabolites were present at lower levels. Sulfonanilide bridge cleavage was not a sign ificant degradation route for cloransulam-methyl in ruminants. These data i ndicated a very low bioaccumulation potential for cloransulam-methyl and it s metabolites in ruminants. For a ruminant exposed to anticipated levels of cloransulam-methyl in its diet, parent and metabolites, in total, would no t be expected to exceed 50 ng/kg in the kidney and liver.