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Abstract
Topsoil, incorporated into pelleted feed, was fed to ewes at the rate of 20 g soil/sheep/day from mid-pregnancy until 3 months after they had lambed. Four ewes received soil containing traces of DDE (control group), and another 4 ewes were given soil containing “weathered” DDT residues (treated group), the latter sheep receiving, on average, 0.62 mg total DDT/sheep/day.
Highest residues in the body fat of all the ewes occurred about 1 month after they had lambed. At this time residue levels averaged 0.45 parts per million (ppm) DDE in the ewes of the control group and 1.53 ppm total DDT (54 percent DDE) in the ewes of the treated group. This difference between groups of about 1 ppm was maintained until the ewes were killed 2 months later.
At similar points in time, concentrations of total DDT were similar in body fat and in the milk fat of the ewes. Residues in the body fat of the lambs were about twice those in their dams, and virtually all of the DDT in the lambs was derived from the ewes via the milk.
The significance of these results is discussed in relation to the ingestion by grazing stock of soil containing residual insecticides.
