ORGANOCHLORINE ACCUMULATION BY SENTINEL MALLARDS AT THE WINSTON-THOMAS SEWAGE-TREATMENT PLANT, BLOOMINGTON, INDIANA

Farm-raised 12-month-old female mallards (Anas platyrhynchos) were rel eased at the Winston-Thomas sewage treatment plant, Bloomington, India na. Five mallards were sacrificed at the start of the study and at app roximately 10-day intervals through day 100. Concentrations of polychl orinated biphenyls (PCBs) in carcasses increased linearly with time of exposure and exceeded 16 mu g/g wet weight by day 100; PCBs in breast muscle exceeded 3.9 mu g/g by day 100. These PCB values are among the highest recorded for wild or sentinel waterfowl. PCB concentrations i n breast muscle (26-523 mu g/g lipid weight) were 50-1,000 times great er than human consumption guidelines for edible poultry in Canada (0.5 mu g/g lipid weight) and 9-176 times greater than consumption guideli nes for edible poultry in the United States (3.0 mu g/g lipid weight). Additionally, PCB concentrations in carcass and breast muscle exceede d the threshold of the Great Lakes Sport Fish Consumption Advisory 'do not eat' category (1.9 mu g/g wet weight) by day 20 and day 50, respe ctively. Hepatic cytochrome P450-associated monooxygenases including B ROD (benzyloxyresorufin-O-dealkylase), EROD (ethoxyresorufin-O-dealkyl ase), and PROD (pentoxyresorufin-O-dealkylase) were induced over 5-fol d compared to reference mallards. BROD, EROD, and PROD were each signi ficantly correlated to total PCBs and to the toxicity of selected PCB congeners, relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin.