Cadmium [Cd, 48]

Cadmium is a metal of the group 12 in the periodic table of elements, and its mean content in the Earth’s upper crust is within the range of 0.1–0.2 mg/kg. In igneous and sedimentary rocks, its contents are fairly similar, 0.2–0.3 mg/kg. Cadmium is considered as one of the most ecotoxic metals that exhibit adverse effects on all biological processes. Cadmium in water is easily absorbed by aquatic biota, which sometimes may be used for biomonitoring. Cadmium concentration in the atmosphere changes from 0.015 in Antarctica to over 4 in rural regions, and to 150 in urban areas. Cadmium is taken up by plants passively, but may be also absorbed metabolically. Cadmium is primarily toxic to the kidney, especially to the proximal tubular cells, where it accumulates over time, and may cause a decrease in the glomerular filtration rate, and eventually renal failure.