Uptake and distribution of 2,5,2',5'-tetrachlorobiphenyl in developing lake trout.

Lake trout (Salvelinus namaycush) eggs, sac fry, and fry in which the yolk had been absorbed were exposed to water containing a 500 μg/liter (ppb) calculated concentration of ¹⁴C-labeled 2,5,2′,5′-tetrachlorobiphenyl (TCB). By determining the amount of radioactivity in water and tissue samples at times ranging from 0.5 to 4 hr, the disappearance of the TCB from the water and its uptake by the animals were followed. The data show that the TCB passed through the egg chorion and accumulated in the yolk. Eggs thus exposed and followed through 4 weeks after hatching lost none of the labeled TCB. Sac fry and fry in which the yolk sac had been absorbed took up the TCB more quickly and accumulated higher concentrations than eggs, achieving concentrations of about 6 ppm in 4 hr. When eggs were exposed to water containing TCB, and the eggs or the sac fry that hatched from them were analyzed, 87–88% of the TCB was found in the yolk. When sac fry were exposed directly to water containing TCB, 70% of the label was found in fry tissues other than the yolk. Thus, the route of entry and the tissue concentration and distribution of TCB in lake trout may depend, in part, on the developmental stage at which the animals are exposed.