Iodine in biology
The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for iodine in 2000. For people age 14 and up, the iodine RDA is 150 μg/day; the RDA for pregnant women is 220 μg/day and the RDA during lactation is 290 μg/day. For children 1–8 years, the RDA is 90 μg/day; for children 8–13 years, 130 μg/day. As a safety consideration, the IOM sets tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. The UL for iodine for adults is 1,100 μg/day. This UL was assessed by analyzing the effect of supplementation on thyroid-stimulating hormone. Collectively, the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).
Malnutrition
Malnutrition in the form of iodine deficiency is "the most common preventable cause of mental impairment worldwide." "Even moderate deficiency, especially in pregnant women and infants, lowers intelligence by 10 to 15 I.Q. points, shaving incalculable potential off a nation's development. The most visible and severe effects—disabling goiters, cretinism and dwarfism—affect a tiny minority, usually in mountain villages. But 16 percent of the world's people have at least mild goiter, a swollen thyroid gland in the neck."