[Harmful elements and iron, zinc and copper: Interactions in the animal and human organism. Part III. Cadmium].

On the basis of a literature survey, the effect of cadmium on the absorption and metabolism of iron, zinc and copper in animal organisms was discussed. The main disturbances in iron metabolism under conditions of exposure to cadmium comprise a reduction of: iron intestinal absorption, iron liver concentration and hematological indices. Cadmium displaces zinc from biologically essential structures, e.g. nucleic acids, enzymes and in the first place from metallothionein. This induces the synthesis of new molecules of that protein, and leads to changes in zinc distribution in the tissues, i.e. to its accumulation in the liver and kidney, and to a decrease in its concentration in e.g. the bone. Cadmium also causes a rise of the copper kidney concentration; the content of the latter element in the liver as well as the activity of some copper-dependent enzymes undergo transient changes. The effect of cadmium greatly depends on its dose and exposure time, as well as on the nutritional state of the subject and on dietary contents of iron, zinc and copper. Special attention has to be directed to supplementation of the deficiencies of these elements in the whole population. Their intakes exceeding the requirements may be advantageous, particularly under conditions of occupational or environmental exposure to cadmium; this problem requires, however, further studies.