Salt
The amount of iodine and the specific iodine compound added to salt varies from country to country. In the United States, the Food and Drug Administration (FDA) recommends [21 CFR 101.9 (c)(8)(iv)] 150 micrograms of iodine per day for both men and women. US iodized salt contains 46–77 ppm (parts per million), whereas in the UK the iodine content of iodized salt is recommended to be 10–22 ppm.
Iodine deficiency
Iodine deficiency resulting in goiter occurs 187 million people globally (2.7% of the population). Certain areas of the world, due to natural deficiency and unavailability of iodine, are severely affected by iodine deficiency, which affects approximately two billion people worldwide. It is particularly common in the Western Pacific, South-East Asia and Africa. Among other nations affected by iodine deficiency, China and Kazakhstan have begun taking action, while Russia has not. Successful campaigns for the adoption of the use of iodized salt require education of salt producers and sellers and a communication campaign directed at the public. The cost of adding iodine to salt is negligible—"Only a few cents a ton."