According to presence in Earth crust, iodine is on 60th place. It belongs in group of hard non-metals and VIIa group of Periodic table of the elements. Iodine is weakly soluble in water. The most continual compounds are sodium and potassium iodides and potassium-iodate. Iodine is using in medicine, paints, photography, and iodine compounds is using in organic compounds, chemistry and medicine.
Origin in water
Only tracks of iodine or iodides find in raw water. In low-mineralized underground waters iodine content is in hundredth and thousandth parts of mg per litre. In larger quantities iodine content is in naphtha's waters. Seawater has larger concentration.
Iodine on concentration from 5 to 50 mg/1 has influence on bacteria and viruses. It is essential element for hormone synthesis of thyroidal gland. Because of iodine loss emanates Bazadovliev disease. NaCl is enriching with potassium-iodide to prevent this disease. Iodine quickly transforms in iron-iodide at successfully absorption in gastrointestinal channel in human metabolism.
Iodine helps proper growth. It gives as more energy. Iodine magnifies mind activity. It helps at hair, nails, skin and teeth health. It is important for proper physical and mental development and for preservation of reproductive power.
Acute poising with iodides is rarely. Chronic poising with iodides (iodisam) is more frequent then acute.
Maximal allowable concentrations
For now, limitary value for iodine is not established.