Uptake and distribution of three PCB congeners and endosulfan by developing white leghorn chicken embryos (Gallus domesticus)

The distributions of PCB 105, 156, 189, and endosulfan in incubating, maternally exposed. viable white leghorn chicken eggs (Gallus domesticus) were investigated. Hens were subcutaneously injected every 4 days with a mixture of the above chemicals. One group of five eggs was removed from the incubator at each of 9, 14, and 19 days of incubation: dissected into three compartments (embryo, chorioallantoic membrane, and yolk + albumin); weighed; frozen; and then later analyzed for the dosing chemicals. Through 19 days of development (90% of incubation), greater than 70% of the total chemical mass in the whole egg remained within the yolk + albumin, whereas, depending on the chemical. 17% to 30% was absorbed by the embryo and 0.2% to 9% was transported into the chorioallantoic membrane. As a percentage of total PCB mass within the respective compartment, PCB 105 composition in the embryo and chorioallantoic membrane decreased significantly throughout development while PCB 156 and 189 composition increased significantly throughout development. Though endosulfan composition within any of the compartments was highly variable, it did not change significantly during development. The results of this study indicate that the majority of avian chick exposure to contaminants occurs posthatch as the chick continues to utilize the residual yolk.