Per Wikipedia; "A common treatment method for preventing iodine-131 exposure is by saturating the thyroid with regular, non-radioactive iodine-127, as an iodide oriodate salt. Free elemental iodine should not be used for saturating the thyroid because it is a corrosive oxidant and therefore is toxic to ingest in the necessary quantities. The thyroid will absorb … Continue reading How To Take Potassium Iodide As A Preventative Against Damage Or Cancer Caused by Radiation From Radioactive Iodine