In New Zealand the emergence of moderate iodine deficiency resulted in a mandate of adding iodized salt to bread: http://www.health.govt.nz/our-work/preventative-health-welln...

The reasons for the deficiency look a lot like the US:

"The re-emergence in iodine deficiency appears to be due to:

* the increased consumption of commercially-prepared foods (manufactured mostly with non-iodised salt)

* the declining use of iodine-containing sanitizers by the dairy industry

* less salt being used in home prepared foods as a response to the health messages to reduce salt intake"