Absorption and accumulation of cadmium, lead and mercury from foods by rats

The purpose of this study was to estimate the apparent absorbability of cadmium (Cd), lead (Pb) and mercury (Hg) from different foods by young rats when these elements occur intrinsically. The study consisted of three independent experiments. In the first experiment rats were fed a casein control diet, a corn-silage diet or an activated-sludge diet. Although the amount of Cd, Pb and Hg ingested from the sludge diet was orders of magnitude higher than that from the casein or corn-silage diet, the absorption of the metals was significantly less (P < 0.02) because these were present as poorly-soluble phosphates. In the second experiment, rats were fed either a commercial fish-meal control diet or an experimental fish-meal diet, with or without the addition of sodium phytate, based on catches from metal-polluted waters. No reduction in absorption resulted from the diet containing phytate as compared with the diet without phytate. The third experiment used the radioactive tracers Cd-115m, Pb-210 and Hg-203 intrinsically incorporated individually into maturing corn ears, on which the three experimental diets were based. The liver and kidney were the main target organs for all three elements (liver: Cd 0.6%, Pb 1.4% and Hg 0.6%; kidney: Cd 0.8%, Pb 0.9% and Hg 1.3%).