EFFECTS OF 3,3',4,4'-TETRACHLOROBIPHENYL, 2,3,3',4,4'-PENTACHLOROBIPHENYL, AND 3,3',4,4',5-PENTACHLOROBIPHENYL ON THE DEVELOPING CHICKEN-EMBRYO WHEN INJECTED PRIOR TO INCUBATION

Great Lakes waterbird populations have experienced less-than-expected hatchability of eggs and a greater-than-expected incidence of developm ental abnormalities. Such deleterious effects have been attributed to polyhalogenated hydrocarbons such as polychlorinated biphenyls (PCBs). PCBs are of primary concern since they are present in significant qua ntities in the environment. Specific PCB congeners, 3,3',4,4'5-pentach lorobiphenyl (IUPAC number 126), 3,3',4,4'-tetrachlorobiphenyl (IUPAC number 77), and 2,3,3',4,4'-pentachlorobiphenyl (IUPAC number 105), we re injected (singly or in combination) into the yolks of White Leghorn chicken (Gallus domesticus) eggs prior to incubation. Teratogenicity was assessed in dead embryos and in hatchlings. Hatchlings were raised for 3 wk to assess body weight gain and mortality. At the end of the 3-wk period, chicks were subjected to necropsy and the brain, bursa, h eart, liver, spleen, and testes were removed and weighed. All 3 congen ers caused increased embryo mortality with approximately 50% mortality occurring at 0.6, 8.8, and 5592 mu g/kg egg for congeners 126, 77, an d 105, respectively. All three congeners also produced significantly m ore abnormalities than the vehicle. Chicks from PCB-injected eggs had lower body weights at wk 2 and 3 of age. Congener 126 caused lower rel ative bursa weights, congener 77 caused greater relative spleen weight s and lower relative liver weights, and all three congeners caused rel ative heart weights to be greater when compared to control.