Radioactive contamination
Some organs concentrate certain elements and hence radionuclide variants of those elements. This action may lead to much lower removal rates. For instance, the thyroid gland takes up a large percentage of any iodine that enters the body. Large quantities of inhaled or ingested radioactive iodine may impair or destroy the thyroid, while other tissues are affected to a lesser extent. Radioactive iodine-131 is a common fission product; it was a major component of the radioactivity released from the Chernobyl disaster, leading to nine fatal cases of pediatric thyroid cancer and hypothyroidism. On the other hand, radioactive iodine is used in the diagnosis and treatment of many diseases of the thyroid precisely because of the thyroid's selective uptake of iodine.
Iodane
Iodane generally refers to any organic derivative of iodine. Without modifier, "iodane" is the systematic name for the parent hydride of iodine, HI. Thus, any organoiodine compound with general formula RI (e.g., CHI or CHI) is a substituted iodane. However, as used in the context of organic synthesis, the term "iodane" more specifically refers to organoiodine compounds with nonstandard bond number (i.e., bond number greater than one), making this term a synonym for hypervalent iodine. These iodine compounds are hypervalent because the iodine atom formally contains more than the 8 electrons in the valence shell required for the octet rule. When iodine is ligated to an organic residue and electronegative ligands (e.g. halides or carboxylates), hypervalent iodine compounds occur with a +3 oxidation number as iodine(III) or λ-iodanes or as a +5 oxidation number as iodine(V) or λ-iodanes. (Here, lambda convention is used to give the nonstandard bond number.)