The effect of preparation and thermal processing on residues of DDT, heptachlor, and their metabolites in turnip greens and roots (brassica rapa)

Most data available on pesticide residues are based on samples of food obtained from the grower or from the market in a fresh state. Until recently very little attention has been given to the effects of commercial processing on pesticide residues in food. Williams (108) indicated that the most common chlorinated hydrocarbon insecticides that were found in a representative “market basket" by the Food and Drug Administration were DDT, TDE, and DDE. Heptachlor and heptachlor epoxide also were found frequently. The Food and Drug Administration (3) has established tolerances of 7.0 p.p.m. for DDT and TDE, and a zero tolerance for heptachlor and heptachlor epoxide. No tolerance was set for DDE. At present. the determination of residues is made on the raw agricultural commodities rather than the finished processed product. This study was made to determine the effects of normal preparation and thermal processing on residues of DDT, heptachlor, and their metabolites in turnips and turnip greens.