Iodine-125 electrons from the radioisotope have been found in one study to do little cellular damage, unless the radionuclide is incorporated chemically directly into cellular DNA, which is not the case for present radiopharmaceuticals which use I-125 as the radioactive label nuclide. As with other radioisotopes of iodine, iodine-125 uptake in the body (mostly to the thyroid) can be blocked with prompt administration of stable iodine-127 in the form of an iodide or iodate salt. Potassium iodide (KI) is typically used for this purpose. Iodine-125 Iodine-125 (I) is a radioisotope of iodine which has uses in biological assays, nuclear medicine imaging
Iodine demonstrated that these animals could survive after eating a 14000 mg/kg dose). Excess iodine can be more cytotoxic in the presence of selenium deficiency. Iodine supplementation in selenium-deficient populations is, in theory, problematic, partly for this reason. The toxicity derives from its oxidizing properties, through which it denaturates proteins (including enzymes). Elemental iodine is also a skin irritant, and direct contact with skin can cause damage and solid iodine crystals should be handled with care. Solutions with high elemental iodine concentration, such as tincture of iodine and Lugol's solution, are capable of causing tissue damage if used in prolonged cleaning