Iodine deficiency--way to go yet.
The Lancet
D002648:Child; D003906:Developing Countries; D006801:Humans; D008607:Intellectual Disability / Q000209:etiology* / Q000517:prevention & control; D007455:Iodine / Q000172:deficiency* / Q000627:therapeutic use; D017673:Sodium Chloride, Dietary / Q000627:therapeutic use*
D017673:Sodium Chloride, Dietary; C034024:iodized salt; D007455:Iodine