Organochlorine insecticide residues in ducklings and their dilution by growth.

Residues of DDT, DDD, DDE, and dieldrin in 7 species of ducklings from Alberta, Canada, were measured. Levels of DDT and metabolites ranged from 0 to 36.48 ppm in fat of 96% of the birds and from 0 to 0.97 ppm im muscle from 67% of the birds. Residue levels of dieldrin ranged from 0 to 2.62 ppm in fat and from 0 to 0.11 ppm in muscle of 43 and 19% of the birds, respectively. Growth dilution was considered to be the most significant factor in reducing the insecticide residue levels in the ducklings. DDT (total DDT, DDE, and DDD) residue levels were decreased with increased weight of pintail (A. acuta), baldpate (Mareca americana), and gadwall (A. strepera) ducklings. Dieldrin used in grasshopper control did not contribute to residue levels in the ducklings. Contamination by DDT was considered to have originated from outside the habitat. No dieldrin or DDT residues were found in ducklings' food sources analysed.