The disorders induced by iodine deficiency affect at least one billion people. Because ofits effects on brain development, iodinedeficiency is the single most preventable cause of mental retardation in the world. Therefore, the United Nations and the Heads of State of almost all the world's countries represented at the Summit for Children in 1990 adopted resolutions to eradicate the disorders induced by iodine deficiency (IDD) by the year 2000. For geological and socio-economic reasons, most of the populations affected by iodine deficiency disorders live in isolated and usually mountainous areas, in pre industrialized parts ofthe world. The problem of iodine deficiency in Europe has been greatly underestimated in the last decades. After the remarkable studies on the effects of iodine deficiency and their prevention and correction in Switzerland, IDD was generally considered no longer a significant public health problem in Europe. However, surveys carried out in the early 1980's under the auspices of the European Thyroid Association, clearly demonstrated the persistence of moderately or even severely affected areas. These surveys also highlighted the lack ofinformation about large parts ofEurope, especially its eastern part. It is only quite recently, following major changes in international relations and thanks to the support of UNICEF, WHO, the International Council for the Control of Iodine Deficiency Disorders and the European Thyroid Association, that more extensive surveys have been conducted in several parts of Europe hitherto almost unexplored. These surveys showed that most European countries were iodine deficient.

Over two billion people worldwide are at risk for the spectrum of disorders known as "The Iodine Deficiency Disorders." 1-10% will suffer cretinism; 5-30% will have some sort of brain damage or neurological impairment and 30-70% will be hypothyroid. The causes of iodine deficiencies can be considered from both simplistic and more complex perspectives: From the leaching of iodine from soil resulting in crops with low iodine content to malnutrition resulting in impaired iodine absorption. Poor dietary diversification and impoverished socio-economic development can also lead to iodine deficiencies. Although it is possible to diagnose and treat deficiencies, there is still an ongoing dialogue regarding the detailed molecular pathology of iodine homeostatis, how hypothyroidism impacts the body tissues, and efficient diagnosis and treatment of the Iodine Deficiency Disorders. This Handbook provides a resource of information on the various pathways and processes based on different countries or diseases. Because there is a constant flow of new information on iodine and related disorders, the goal of this Handbook is to provide a base of scientific information upon which additional knowledge can be applied. Provides important information on one of the most common micro-nutrient deficiencies in the world, the most important "single nutrient-multiple consequences" paradigm today Includes information on iodine-related diseases, including those that are common, preventable and treatable Provides insight from a broad perspective of viewpoints -- from subcellular transports to economic impact