Sep 30, 2018 · Only a small percentage of salt in US comes from table salt. Almost 70% of salt in diet comes from processed foods, which mostly use non-iodized salt (Dasgupta 2008). Americans obtain iodine from many sources although dairy and grain products remain the primary sources of iodine in the American diet (Murray 2008).
The addition of iodine to salt or drinking water is credited with the reduction or elimination of cretinism and goiter, although cretinism still remains a serious problem in many rural sections of China. In coastal areas, the action of ocean waves makes iodine gas. Once airborne, iodine combines with water or air and enters the soil.
Iodine often ends up in surface water from waste water treatment plants, including radioactive isotopes. Iodine is retained by sludge for 2-25%. The residue remains in water, causing effluents to contain between 1 and 16 μg/L. High iodine concentrations may be present near chemical waste dumps.