Iodine geochemistry and environmental controls on iodine deficiency disorders : a new approach to a classic geochemistry and health problem

A lack of iodine in the diet is the classic example of how the deficiency of a trace element in the environment can impact on human health. It is reported that globally 2.2 billion people (38% of the world's population) live in areas with iodine deficiency and risk its complications. The problem is to a large extent successfully being tackled with medical intervention techniques leaving many questions about the role of iodine's behaviour in the environment unanswered. What, for example, do we mean by an iodine deficient environment? If this is defined as an area providing inadequate iodine in a diet of locally produced food, all but the coastal areas of the world would be considered as being iodine deficient.