Iron toxicity is a condition caused the overingestion of iron, usually in the form of supplements. Metallic iron and rust are not soluble in water and rarely cause iron toxicity if ingested. However, dietary forms of iron are metabolized far more quickly in the stomach and can quickly overload the body's organs. Death is usually from liver failure.
The toxic dose is based on body weight and, as a result, young children are the most likely to be accidentally poisoned. Iron supplements tend to be sweet in taste and toxicity starts at about 10 mg of elemental iron for every kg of body weight. Ferrous sulfate, ferrous gluconate and ferrous fumarate are all common supplements used to treat anemia. Ferrous fumanate contains over 100 mg of elemental iron, so three are enough to bring on serious symptoms in a 30 kg child.
Initially, the iron attacks the lining of the stomach, resulting in pain, nausea and vomiting. These symptoms disappear quickly as the iron is digested, but then the iron tends to accumulate in the brain and liver.
Due to changes in packaging and warnings, iron toxicity rarely results in deaths nowadays (and there have been no deaths in the United States from the condition since 1998). Treatment is with chelation therapy to bind to the iron and, if necessary, dialysis, which will also remove the iron from the bloodstream.
See also Hemochromatosis.