Tissue distribution, excretion, and metabolism of 1,2,7,8-tetrachlorodibenzo-p-dioxin in the rat

A tissue distribution, excretion, and metabolism study was conducted using a relatively non-toxic dioxin congener, i.e., 1,2,7,8-tetrachlorodibenzo-p- dioxin (1278-TCDD), to gain a better understanding of mammalian metabolism of dioxins. Conventional, bile duct cannulated, and germ free male rats wer e administered mg/kg quantities as a single oral dose. Elimination of 1278- TCDD was largely complete by 72 h. Distribution of [C-14]1278-TCDD was low in all tissues examined. Metabolites were identified in urine, bile, and fe ces by negative ion FAB-MS and H-1-NMR, or GC/MS. The major fecal metabolit e was a NIH-shifted hydroxylated TCDD. The bile contained a glucuronide con jugate of this hydroxy TCDD, and a diglucuronide conjugate of a dihydroxy-t riCDD. The major metabolites in urine were glucuronide and sulfate conjugat es of 4,5-dichlorocatechol. (C) 2001 Elsevier Science Ltd. All rights reser ved.