What side effects do you mean? The only one I'm aware of is the Wolff–Chaikoff effect, but for most people that's only temporary as they adapt to the excess iodine.
Right now there's actually an issue with iodine deficiency in the US because of the trendy use of pink Himalayan salt, various sea salts, or Kosher salt that are all non-iodized.
Citation please? I find this very hard to believe for a number of reasons.
1) Most salt intake in the US is through packaged and prepared foods, not table salt. 2) The American Thyroid Association disagrees with you - "In the United States, iodine status has remained generally adequate in the last 2 decades" 3) There are many commonly consumed foods in the US that contain iodine other than iodized table salt