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What Are Toxic Metals?


Lead ore

Toxic metals are metals that form poisonous soluble compounds and have no biological role, i.e. are not essential minerals, or are in the wrong form. Often heavy metals are thought as synonymous, but lighter metals also have toxicity, such as beryllium, and not all heavy metals are particularly toxic, and some are essential, such as iron. The definition may also include trace elements when considered in abnormally high, toxic doses. A difference is that there is no beneficial dose for a toxic metal with no biological role.

Toxic metals sometimes imitate the action of an essential element in the body, interfering with the metabolic process to cause illness. Many metals, particularly heavy metals are toxic, but some heavy metals are essential, have a low toxicity, and bismuth is non-toxic. Most often the definition includes at least cadmium, lead, mercury and the radioactive metals. Metalloids (arsenic, polonium) may be included in the definition. Radioactive metals have both radiological toxicity and chemical toxicity. Metals in an oxidation state abnormal to the body may also become toxic: chromium(III) is an essential trace element, but chromium(VI) is a carcinogen.


Lead is the most widespread non-essential trace element. It is a powerful neurotoxin, has DNA-damaging effects and is teratogenic (affects the fetus). In our environment it is commonly found in petrol and cosmetics. Once absorbed it is stored in the bones and soft tissues and adversely affects the absorption and utilization of iron, zinc and calcium.


Atmospheric levels are low, but is bio-accumulates into highly toxic forms in the food chain — in particular seafood such as swordfish and tuna. In the case of amalgam fillings, vapor is released and increased upon stimulation by chewing, eating or tooth brushing. Toxicity may result in muscle weakness, mood swings and memory loss.


Cadmium appears to have no biological function. It concentrated in the kidneys, causing hypertension and bone damage. It is extremely high in cigarette smoke and is also found in food sources such a tuna, liver and kidney as well as tomatoes and potatoes. It is mainly stored in the liver and the kidneys.


Aluminium is found in household foil, beverage cans, kitchen utensils, food, medication and cosmetics. Excess aluminium is stored in the brain, bones and liver. Raised aluminum levels in children are associated with behavioral disorders.

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