Dicofol residues in eggs and carcasses of captive American kestrels.

American kestrels (Falco sparverius) were fed diets containing 0 (control), 1, 3, 10, and 30 microgram/g (wet wt) of Kelthane. Residues of dicofol and its metabolites were then analyzed in the eggs and carcasses of females. Significant differences occurred among treatments for residues of both p,p'-dicofol and p,p'-dechlorodicofol (DCD) in both eggs and carcasses and for p,p'-dicholorbenzophenone (DCBP) in eggs. Residue concentrations increased with increasing treatment exposure. Residues of p,p'-dicofol, p,p'-DCD, and p,p'-DCBP in eggs were significantly correlated with eggshell quality parameters. Significant correlations also occurred among contaminants in eggs and for individual contaminants between eggs and carcasses. The lowest-observed-dietary-effect concentration for eggshell thinning was 3 microgram/g, whereas 1 microgram/g may be considered to be near a no-observable-adverse-effect concentration. Concentrations of dicofol in potential prey items and eggs of wild birds generally have been lower than dietary-effect concentrations or concentrations in tissues or eggs associated with eggshell thinning and reduced reproductive success.