Differences in sensitivity of some avian species to the embryotoxicity of a PCB, 3,3′,4,4′-tetrachlorobiphenyl, injected into the eggs

Eggs of pheasant Phasianus colchicus, mallard Anas platyrhynchos, goldeneye Bucephala clangula and black-headed gull Larus ridibundus were injected with 3,3′,4,4′-tetrachlorobiphenyl (TCB) into the yolks. The highest dose given was 0·1 mg per kilogram of egg (mallard) or 1·0 mg per kilogram of egg (pheasant, goldeneye and black-headed gull). Only in the pheasants' eggs was any effect on hatchability noted. Injection of 1·0 mg TCB per kilogram of egg resulted in the death of all the pheasant embryos, but no decrease in the hatching rate occurred when 0·1 mg TCB per kilogram was injected. Embryos of the species studied appear to be considerably less sensitive than chick embryos to the toxic action of TCB. The concentration of TCB in the embryos of some of the injected eggs was determined in chickens, pheasants and goldeneyes. No difference was found in the concentration of TCB in the embryos to explain the difference in effect on hatchability.