Potassium iodate is used to add iodine to salt. It is better than potassium iodide because it does not oxidize to iodine and evaporate like potassium iodide does. It is sometimes used in flour just like potassium bromate.
It is also used for radiation protection. A nuclear explosion can make radioactive iodine, which goes into the thyroid and can make cancer. Eating potassium iodate makes the thyroid full of nonradioactive iodine and prevents radioactive iodine from going in. It lasts longer than potassium iodide.