Comparison of the concentrations of polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in maternal and fetal blood, amniotic and allantoic fluids in cattle

To characterize the maternal-fetal transport of lipophilic endocrine disrupting chemicals, concentrations of polychlorinated (2,3,7,8-substituted) dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) were measured in maternal and fetal blood, and amniotic and allantoic fluids in cattle. Total toxicity equivalent quantity (TEQ) was highest in amniotic fluid on a fat-weight basis, whereas it was highest in maternal blood on a total weight basis. TEQ was lowest in allantoic fluid on either basis; 26 of 29 congeners analyzed in this experiment were detected in one or more samples. The largest number of congeners was detected in amniotic fluid. O₈CDD, 2,3,4,7,8-P₅CDF and 2,3′,4,4′,5-P₅CB were the major congeners in PCDDs, PCDFs and PCBs, respectively. The O₈CDD concentration was higher in fetal blood than in maternal blood on a fat-weight basis, whereas concentrations of other congeners were lower in fetal blood than in maternal blood. Furthermore, on a fat-weight basis, the O₈CDD concentration was considerably higher in allantoic fluid compared with other samples. Concentrations of major PCB congeners were higher in amniotic fluid than in maternal and fetal blood on a fat-weight basis. In conclusion, it is suggested that lipophilic endocrine-disrupting chemicals contained in maternal blood are all transferred to the fetal circulation via the placenta in cattle. Furthermore, the results of this experiment imply that O₈CDD has different transportation systems from other dioxins in the circulation, and that a considerable amount of PCBs is excreted and accumulated in amniotic fluid during the fetal stage in cattle.