Environmental Contamination of Flue-Cured Tobacco with Chlorinated Hydrocarbon Insecticides

Indirect contamination of tobacco by DDT, TDE, endrin, dieldrin, and toxaphene was investigated under field conditions. Levels of DDT + TDE in soil ranged from << 0.01 to 0.18 ppm, and those in cured leaves ranged from 0.11 to 1.69 ppm. The lower stalk position at the major test location generally had greater concentrations of DDT + TDE than the middle and upper positions, but distribution of these insecticides among leaf positions was variable for other locations. Residues of DDT in the bottom stalk position were positively correlated with those in the soil. Plant-bed soils did not appear to be a major source of DDT + TDE residues in cured tobacco. Residues of endrin and dieldrin were near or below the limit of detection (0.01 ppm) in soil and cured leaf. Residues of toxaphene ranged from << 0.1 to 4.7 ppm in soil and << 0.3 to 7.7 ppm on tobacco. Toxaphene residues in the bottom and top stalk positions were positively correlated with residues in soil. Contamination by toxaphene appeared to be attributable to uptake from soil and to movement of the insecticide as drift or vapour through the air.