Nearly 70% of single oral doses of 14C-labelled pentachloronitrobenzene (PCNB) was excreted in bile within 24 h. 2. The characterized biliary metabolites of PCNB were either mercapturic acid pathway metabolites or catabolites thereof (thiols, methylthiols, S-glucuronides). 3. A major biliary metabolite was S-(aminotetrachlorophenyl)glutathione. 4. Conjugation with glutathione with subsequent catabolism to bis-methylthiotetrachlorobenzene was the major pathway in the control rat. 5. Germ-free experiments showed that only nitro- group displacement occurred, and no nitro- group reduction was detected.
