Cadmium is unique among the metals because of its combination of toxicity in low dosages, long
biological half-life (of about 30 years in humans), its low rate of excretion from the body and the fact that it is stored predominantly in the soft tissues (liver and kidney). There has been an increase in exposure to
cadmium because its presence in
fertilizers and sewage sludge and also its increased industrial use in Cd-Ni batteries. Although there are a number of reports on occupational and environmental exposures to
cadmium compounds, treatment of
cadmium poisoning has been difficult because there is neither a safe practical means of evaluating bioavailable body burden nor is there a recommended therapeutic
chelating agent for chronic
cadmium intoxication. In this review, the various factors affecting the chelation of
cadmium such as its binding to intracellular
metallothionein, the structural requirements of compounds for effective removal of
cadmium, the excretion pattern of
cadmium after its mobilization from intracellular stores and the recent developments in the design and synthesis of new compounds for
cadmium chelation are discussed. The importance of protecting sensitive organs such as kidney and brain during
cadmium chelation is addressed. The progress made during the last decade on the synthesis of new compounds, especially derivatives of dithiocarbamates, is remarkable. Some of these compounds provide promise for development of a useful and safe therapeutic
chelating agent which can be used for the assessment of
cadmium body burden and for preventive removal of
cadmium as well as for use in overt
cadmium poisoning in humans.