The Effect of Dosage Level and Various Methods of Administration on the Concentration of DDT in Milk

Abstract

Summary Higher concentrations of DDT in the milk occurred when cows were fed DDT as a residue on field-sprayed alfalfa than when comparable dosages of crystalline DDT were fed, suggesting that possibly intestinal absorption of DDT residues from sprayed forages is more complete than by other methods of administration, or that more DDT might be stored in the body fat when fed as the crystalline material while a smaller proportion is excreted in the milk fat. There were no consistent differences in the excretion of DDT in the milk when the DDT was fed as a soybean oil solution either in capsules or mixed with grain, or as crystalline DDT fed either in capsules or mixed in grain. Additions of small amounts of detergents to the soybean oil solution of DDT had no effect on the concentration of DDT in the milk. Increasing dosage levels of crystalline DDT gave progressive increases in the DDT concentration of the milk in a straight line relation. Increasing intakes of DDT as a residue on sprayed alfalfa also gave a straight-line increase in DDT excretion in the milk but at a greater slope than with crystalline DDT. Estimated concentrations of DDT in the milk may be calculated for any intake and either method of administration from the corresponding slope of the regression line.