Iodine levels of iodine-131 is the chance occurrence of radiogenic thyroid cancer in later life. Other risks include the possibility of non-cancerous growths and thyroiditis. The usual means of protection against the negative effects of iodine-131 is by saturating the thyroid gland with stable iodine-127 in the form of potassium iodide tablets, taken daily for optimal prophylaxis. However, iodine-131 may also be used for medicinal purposes in radiation therapy for this very reason, when tissue destruction is desired after iodine uptake by the tissue. Iodine-131 is also used as a radioactive tracer. Though it is the least reactive of the halogens,
Tincture of iodine Strong Iodine Tincture is defined in the NF as containing in each 100 mL, 6.8 to 7.5 gram of iodine, and 4.7 to 5.5 gram of potassium iodide. Purified water is 50 mL and the balance is alcohol. This 7% tincture solution is about 3.5 times more concentrated than USP 2% tincture. As in the case of Lugol's iodine, the role of iodide in the solution is to increase the solubility of the elemental iodine, by turning it to the soluble triiodide anion I. However, since iodine has moderate solubility in ethanol, it is also assisted by this solvent directly.