Iodine are between 110 and 130 µg for infants up to 12 months, 90 µg for children up to eight years, 130 µg for children up to 13 years, 150 µg for adults, 220 µg for pregnant women and 290 µg for lactation. The Tolerable Upper Intake Level (UL) for adults is 1,100 μg/day. This upper limit was assessed by analyzing the effect of supplementation on thyroid-stimulating hormone. The thyroid gland needs no more than 70 μg/day to synthesise the requisite daily amounts of T4 and T3. The higher recommended daily allowance levels of iodine seem necessary for optimal function of
Isotopes of iodine and 1970s reached about 10). I differs from Cl in that its half-life is longer (15.7 vs. 0.301 million years), it is highly biophilic, and occurs in multiple ionic forms (commonly, I and IO), which have different chemical behaviors. This makes it fairly easy for I to enter the biosphere as it becomes incorporated into vegetation, soil, milk, animal tissue, etc. Of the many isotopes of iodine, only two are typically used in a medical setting: iodine-123 and iodine-131. Since I has both a beta and gamma decay mode, it can be used for radiotherapy or for imaging. I, which