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).
Iodine deficiency in China
The Chinese government implemented a program of regulating salt to contain iodine starting in 1995. A more recent study has confirmed that the availability of iodized salt in the provinces has increased since this date. Today, about one third of the Chinese population is living in areas with low concentrations of iodine in their water supply. Salt is available in China for less than the retail price in some other countries, at about 5 cents, and is consumed regularly in most diets. This is very cost effective for producers who now must abide by the iodized salt regulations and those for those who need to consume it. The black market, however, is laden with the non-iodized counterpart and partially accounts for the population still be fairly saturated with IDDs.