Organochlorine and mercury residues in canvasback duck eggs, 1972-73

Eggs of canvasback ducks (Aythya valisineria) from several major breeding areas were analyzed for organochlorine and mercury residues. Polychlorinated biphenyls (PCBs) were detected in 96 of 97 eggs, in concentrations up to 29 ppm (wet wt.). DDE occurred in 79 percent of the samples with a maximum residue of 12 ppm (wet wt.). DDT, DDD, dieldrin, hexachlorobenzene, cis-chlordane, heptachlor epoxide, and oxychlordane were detected less frequently. Mercury was detected in only 6 of 34 eggs analyzed. Most of the eggs contained concentrations of organochlorines and mercury below levels known to cause adverse effects on avian survival or reproduction.