Absorption of DDT and Parathion by Fruits

Commensurate with the need for information on the effectiveness of new organic insecticides has been the need for determining the magnitude and distribution of toxic residues on and in edible produce. Absorption of insecticide residues of DDT and parathion by fruit was investigated. Specific techniques for the physical separation of component fruit parts with minimization of sample contamination are described. DDT residues were analyzed by the dehydrohalogenation method. The magenta color reaction as modified by Gunther and Blinn was used for parathion residues. Results indicated the presence of DDT and parathion in the peel but not in the pulp of harvested citrus fruits. The relatively rapid penetration of the toxicants was followed by a slower loss with the retention of appreciable amounts over long periods of time. Neither DDT nor parathion was found in the pulp of apples, pears, or peaches following treatment with standard dosages in sequence applications. Spectrographic examination of transmission—wavelength curves of the benzene extractives of DDT-treated and parathion-treated navel oranges in comparison with curves for parent compounds indicated definite shifts in absorption bands.