Importance of Feed as an Unavoidable Source of Pesticide Contamination in Poultry Meat and Eggs

DDT and metabolites, dieldrin, heptachlor epoxide, and lindane pesticide residues accumulated in the body tissues and the eggs of laying hens in direct proportion to the concentration of the pesticide or its parent compound in feeds. Methoxychlor residues did not accumulate at any of the concentration levels used in the study. Plateaus of residue accumulation occurred independently for each pesticide concentration after 6 to 12 weeks of feeding at which time, as long as the concentration in the feed remained constant, the apparent elimination or metabolism of the pesticide residue balanced the intake. The concentration of residues in eggs at the plateau was directly proportional to and dependent on the concentration in the feed. The same direct relationship existed between the concentration of pesticide residue in the feed and the residue in the body tissues. The significance of pesticide contamination in eggs resulting from feeding levels of 0.1 p.p.m. and less is highly questionable because concentrations in eggs were generally below 10 p.p.b. and very seldom exceeded 50 p.p.b. Although higher concentrations of pesticide residues were found in the body fat at the 0.1 p.p.m. level, the transfer of residue to the egg did not appear to be important.