Availability of cadmium from lettuce leaves and cadmium sulfate to rats

The availabilty of cadmium in lettuce leaves and in cadmium sulfate to male rats was studied. Both zinc-depleted and zinc-adequate rats were fed single doses of either /sup 109/Cd-labeled cadmium sulfate or /sup 109/Cd-labeled lettuce leaves. Lettuce plants (Lactuca sativa, var. 'Black Seeded Simpson') were grown in /sup 109/Cd-labeled nutrient solutions that contained either 0.045 or 0.225 ppm cadmium and either 0.131 or 0.654 ppm zinc. Increasing cadmium supply to the plants increased cadmium concentration in the leaves but had no effect on leaf zinc levels. Increasing zinc supply to the plants increased zinc concentration in the leaves and decreased cadmium levels in leaves of plants supplied the higher level of cadmium. Cadmium availability, as indicated by percent of /sup 109/Cd absorbed, was greater from lettuce leaves than from cadmium sulfate. Absorption of /sup 109/Cd depended on the source, and averaged from 1.6 to 4.7% of the dose in zinc-depleted rats and from about 0.9 to 1.2% of the dose in zinc-adequate rats. Increasing the amount of zinc in leaves of plants supplied the higher level of cadmium decreased the availability of cadmium in the leaves to zinc-depleted rats.