Effect of dietary lead intake on lead retention in adult rats.

132 female rats with a live weight of 177 to 224 g were provided over a period of 17 days a half-synthetic diet with a lead concentration of 0.4 mg/kg. Then 120 of the animals were divided into 15 treatment groups fed with a diet different in Pb content (0.02, 0.04, 0.08, 0.12, 0.22, 0.42, 0.62, 0.82, 1, 5, 10, 50, 100, 400 and 800 mg Pb2+ per kg) over a period of 29 days. The feed was rationed so as to provide the minimum energy maintenance requirement. Pb retention dependent on different lead supplies was determined by subtracting the Pb contents of carcasses of 12 reference animals sacrificed at the beginning of the experiment from the Pb content of carcasses of rats at the end of the experiment. Up to a Pb concentration of 0.42 mg/kg in the diet Pb retention fluctuated around zero. Then the retention was slightly positive up to 5 mg/kg Pb in the diet. Up to 10 mg/kg Pb in the diet Pb retention increased sharply. Concentrations of iron, copper, zinc, and manganese in carcasses were affected only slightly by the varying concentration of lead in the diet.