Metal toxicity

Metal toxicity or metal poisoning is the toxic effect of certain metals that accumulate in the environment and damage ecosystems, plants and animals, including human health.^[1][2][3] Environmental pollution with heavy metals can result in contamination of drinking water, air, and waterways, accumulating in plants, crops, seafood, and meat.^[3] Such pollution may indirectly affect humans via the food chain and through occupational or domestic exposure by inhalation, ingestion, or contact with the skin.^[1][3]

At low concentrations, heavy metals such as copper, iron, manganese, and zinc are essential nutrients obtained through the diet supporting health, but have toxicity at high exposure concentrations.^[2] Other heavy metals having no biological roles in animals, but with potential for toxicity include arsenic, cadmium, lead, mercury, and thallium.^[1][2][4]

Some metals are toxic when they form poisonous soluble compounds which interfere with enzyme systems, such as superoxide dismutase, catalase, or glutathione peroxidase.^[1] Only soluble metal-containing compounds are toxic by forming coordination complexes, which consist of a metal ion surrounded by ligands.^[1] Ligands can range from water in metal aquo complexes to methyl groups, as in tetraethyl lead.

Toxic metal complexes can be detoxified by conversion to insoluble derivatives or by binding them in rigid molecular environments using chelating agents. An option for treatment of metal poisoning may be chelation therapy, which involves the administration of chelation agents to remove metals from the body.^[3]