Toxicokinetic mixture interactions between 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,2',4,4',5,5'-hexachlorobiphenyl in the liver of neonatal rats after pre- and postnatal exposure

Abstract Pregnant rats received single oral doses of either 1.39 μg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD/kg), 164 mg 2,2',4,4',5,5'-hexachlorobiphenyl (HxCB)/kg, or a mixture of both compounds at day 16 of gestation. The hepatic deposition of the compounds as well as CYP1A dependent 7-ethoxyresorufin-O-deethylation (EROD) and CYP2B dependent 7-pentoxyresorufin-O-depentylation (PROD) activity were studied in the mothers and offspring at day 10 after delivery. The HxCB deposition in the livers of mothers and offspring was approximately doubled when this compound was coadministered with TCDD but HxCB coadministration did not influence hepatic TCDD deposition. It is concluded that the mechanisms behind the toxicokinetic interactions between PCDDs and di-orthosubstituted PCBs in the liver are probably different for both groups of compounds.