Iodine deficiency is so prevalent that almost a ⅓ of the world's population suffers. Iodine sufficiency is defined as ingestion of 150 ㎍ per day - or 200 ㎍ if pregnant or breastfeeding - by the World Health Organization.
In my opinion, these amounts are about 80 times lower than what should be ingested.
The following are some disorders caused by iodine deficiency:
Assessment of Iodine DeficiencyDisorders and Monitoring their Elimination copyright 2001 by the World Health Organization (pdf)