No, iodine deficiency does not only occur in third world countries. We are seeing an increase in iodine deficiency in developed countries. The largest sources of iodine is in sea vegetables and ocean fish, therefore diets lacking in seafood can lead to iodine deficiency. The increase of bromine, chlorine and flouride in our environment can displace iodine, leading to iodine deficiency and this problem is not isolated to third world countries, it is a serious issue in developed nations. Since less people are consuming iodized salt, even though absorption is low and quality of the iodine is low, this decreased consumption has contributed to an increase in iodine deficiency, even in developed countries.