EFFECTS INDUCED BY FEEDING ORCANOCHLORINE-CONTAMINATED CARP FROM SAGINAW BAY, LAKE-HURON, TO LAYING WHITE LEGHORN HENS .2. EMBRYOTOXIC AND TERATOGENIC EFFECTS

Carp from Saginaw Bay, Lake Huron, MI, was fed to While Leghorn chicke ns for a period of 8 wk. The diets contained 0.3 (control; 0% carp), 0 .8 (3.4% carp), and 6.6 (35% carp) mg polychlorinated biphenyls (PCBs) /kg diet by wet weight (ww). These concentrations corresponded to 3.3, 26, and 59 pg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents/ g diet ww, respectively. Though the diets were not acutely toxic to th e adult laying hens, dose- and time-dependent responses were observed in the embryos and chicks. Toxicity was manifested as a dose-dependent increase in embryo mortality and decreased hatching races. Furthermor e, embryos and chicks displayed Various deformities, including iii hea d and neck edema and hemorrhage, (2) abdominal edema and hemorrhage, ( 3) foot and leg deformities, (4) skull and brain deformities, (5) yolk -sac deformities, and (6) miscellaneous deformities. The types of defo rmities observed were similar to those reported for embryos and chicks of colonial waterbirds in Saginaw Bay, as well as in controlled studi es where technical mixtures or individual congeners of polychlorinated diaromatic hydrocarbons (PCDAHs) were fed to chickens. increasing con centrations of carp also significantly affected the various organ weig hts in 18-d embryos and hatched chicks. At 18 d of incubation, weights of the embryos' fivers were directly proportional to the concentratio n of PCBs in the diets. The weights oi the spleens and bursae were inv ersely proportional to the dietary PCB concentration. After 3 addition al days of incubation, significant effects in body, brain, fiver, hear t, and bursa weights were observed in hatched chicks. The concentratio ns of total PCBs, as well as 2,3,7,8-TCDD equivalents (TEQs) in the di ets, were in the range of those that have been shown to cause similar adverse effects in other species. This study has shown that fish, the primary food source of colonial waterbirds in Saginaw Bay, are capable of causing adverse reproductive effects in a model avian species, the chicken. However, due to differences in the relative potency to cause effects on different endpoints in different species, the results of t his study should not be used to predict the threshold for effects in o ther species.