Iodine in biology damage). In areas where there is little iodine in the diet, typically remote inland areas and semi-arid equatorial climates where no marine foods are eaten, iodine deficiency also gives rise to hypothyroidism, the most serious symptoms of which are epidemic goitre (swelling of the thyroid gland), extreme fatigue, mental slowing, depression, weight gain, and low basal body temperatures. The addition of iodine to table salt (so-called iodized salt) has largely eliminated the most severe consequences of iodine deficiency in wealthier nations, but deficiency remains a serious public health problem in the developing world. Iodine deficiency is also a problem in
Tincture of iodine drinking. When an alcohol solution is not desirable for this purpose, the alcohol-free Lugol's iodine, an aqueous solution of iodine in potassium iodide solution, or else povidone-iodine (brand names Wokadine, Betadine), a PVPI solution, can be used. Small amounts may be added to suspect drinking water as a disinfectant (typically 5 mg free iodine per liter, or 5 drops of 2% tincture). Though this treatment is effective against bacteria and virus, it does not protect against protozoan parasites such as "Cryptosporidium" and "Giardia". Iodine solution is used to sanitize the surface of fruit and vegetables for bacteria and virus. The