3,3',4,4'-tetrachloro[14C]biphenyl in pregnant mice: enrichment of phenol and methyl sulphone metabolites in late gestational fetuses.

The distribution of radioactivity after injection of 3,3',4,4'-tetrachloro[14C]biphenyl (14C-TCB) in pregnant mice was determined by autoradiography and computer-assisted densitometric analysis. TCB metabolites in fetal tissue were analysed by g.l.c. and g.l.c.-mass spectrometry and compared to the synthesized reference compounds 2-, 5- and 6-methoxy-3,3',4,4'-tetrachlorobiphenyl. The concentration of radioactivity was high in the uterine fluid, and in the fetuses in late gestation. Fetal radioactivity decreased after pretreatment with a high dose of unlabelled TCB. Radioactivity was reversibly bound to fetal tissues. A phenolic metabolite, 3,3',4,4'-tetrachloro-2-biphenylol, and a methylsulphonyl-tetrachlorobiphenyl were found in fetuses in late gestation. No unmetabolized TCB was detected in the fetuses.