Hydroxylated polychlorinated biphenyls : distribution in the pregnant mouse

Abstract

1. In the pregnant C57BL mouse the disposition of a single, intravenous low dose of ¹⁴C-labelled 4-hydroxy-3,5,3',4'-tetrachlorobiph enyl (4-OH-TCB) or 4-hydroxy3,5,2',3',4'-pentachloro- biphenyl (4-OH-PeCB1) was monitored by liquid scintillation counting and whole-body autoradiography. The compounds were placentally transferred and accumulated in the foetal tissues (e.g. plasma and liver). Also, maternal accumulation was observed in selected tissues, including liver, adrenal gland, adipose tissue and yolk sac placenta. 2. The foetal concentration of both hydroxy- PCBs increased with time up 24 h postexposure and the foetal plasma concentration with at this time-point two-fold of that in maternal plasma. Chemicalanalysis of maternal plasma and liver showed no metabolismof the administered compounds. 3. In the pregnant C57BL mouse at late gestation, exposure to 4-OH-TCB generally resulted in a higher foetal and maternal tissue retention than did 4-OH-PeCB1. The estimated elimination half-lives (t_1/2) of 4-OH-TCB in maternal liver and plasma were 69 and 13 h respectively, and for 4-OH-PeCB1 were 17 and 13 h. 4. No differences in foetal tissue concentration of 4-OH-TCB were observed between the C57BL and NMRI mouse. In contrast, earlier studies have shown that the PCB congener CB-77, the parent compound of 4-OH-TCB, resulted in a C57BL NMRI foetal ratio of 1:5.