Mixed-function oxygenases, oxidative stress, and chromosomal damage measured in lesser scaup wintering on the Indiana Harbor Canal

During the winter of 1993-1994, male lesser scaup (Aythya affinis) were col lected on the heavily polluted Indiana Harbor Canal, East Chicago, Indiana, and examined for several bioindicators of chemical exposure. Livers were a nalyzed for activities of three cytochrome P450-associated monooxygenases a nd four measures of oxidative stress. Blood and spleen were analyzed by flo w cytometry for chromosomal damage. In a concurrent study, scaup tissues we re analyzed for organic and inorganic contaminants. Ethoxyresorufin-O-dealk ylase (EROD) activity in livers of scaup collected in January 1994 was sign ificantly higher than in livers of scaup collected in March 1994 or in live rs of reference birds. Three hepatic monooxygenase activities were each sig nificantly correlated with polycyclic aromatic hydrocarbon (PAH) concentrat ions in scaup carcasses. Thiobarbituric acid (TBA) activity in scaup livers was positively correlated with iron, boron, and lead concentrations in liv ers and polychlorinated biphenyl concentrations in carcasses. TBA activity was negatively correlated with protein-bound thiol activity and mercury con centrations in livers. The coefficient of variation of DNA content in scaup blood cells was correlated with PAH concentrations in scaup carcasses. Thi s is the first field study with birds to demonstrate a correlation between liver monooxygenase activity and carcass PAH concentrations and to show a d irect correlation between PAH concentrations in tissues and somatic chromos omal damage in blood.