The salt industry plays an indispensible role in the global campaign against Iodine Deficiency Disorders by producing iodized salt. <more >
Modern salt plants routinely spray potassium iodide or potassium iodate onto the salt while it moves along a conveyor belt before it is packaged. In lower-tech operations, iodine is sometimes added as a dry ingredient and physically mixed with the salt. Generally, iodized salt contains 0.002% to 0.004% iodine, supplied either as potassium iodide or potassium iodate.
In the U.S., iodine is added as potassium iodide in table salt at slightly higher levels (0.006% to 0.01% potassium iodide, equivalent to 0.0046% to 0.0077% iodine. Potassium iodide is one of two sources of iodine permissible by the U.S. Food and Drug Administration. Although animal feeds are fortified with iodine in the form of potassium iodate, the form most commonly used globally to iodize food salt outside the U.S. because of its greater stability, FDA does not approve potassium iodate to fortify food salt in the U.S. Therefore, U.S. salt producers add sodium carbonate or sodium bicarbonate when they iodize salt to increase alkalinity, and sodium thiosulfate or dextrose to stabilize potassium iodide. Without a stabilizer, potassium iodide is oxidized to iodine and lost by volatilization from the product.
Outside the U.S. iodine is most commonly added as the more stable potassium iodate and at lower, varying levels.