Iodine in biology
The U.S. Food and Nutrition Board and Institute of Medicine recommended daily allowance of iodine ranges from 150 micrograms per day for adult humans to 290 micrograms per day for lactating mothers. However, the thyroid gland needs no more than 70 micrograms per day to synthesize the requisite daily amounts of T4 and T3. The higher recommended daily allowance levels of iodine seem necessary for optimal function of a number of other body systems, including lactating breasts, gastric mucosa, salivary glands, oral mucosa, arterial walls, thymus, epidermis, choroid plexus and cerebrospinal fluid, among others.
Iodine-131
To completely block the uptake of iodine-131 by the purposeful addition of perchlorate ions to a population's water supply, aiming at dosages of 0.5 mg/kg-day, or a water concentration of 17 ppm, would therefore be grossly inadequate at truly reducing radioiodine uptake. Perchlorate ion concentrations in a region's water supply would therefore need to be much higher, with at least a total dosage of 7.15 mg/kg of body weight per day needing to be aimed for, with this being achievable for most adults by consuming 2 liters of water per day with a water concentration of 250 mg/kg of water, or 250 ppm of perchlorate ions per liter; only at this level would perchlorate consumption offer adequate protection, and be truly beneficial to the population at preventing bioaccumulation when exposed to a radioiodine environment. This being entirely independent of the availability of iodate or iodide drugs.