Iodine deficiency affects over a quarter of world population.

• Author: Mitchell, Jennifer
• Position: Environmental Intelligence

Despite huge gains in programs that add iodine to food, some 1.6 billion people remain vulnerable to a range of crippling health problems because their diets do not contain enough of this essential element, according to the World Health Organization (WHO). One-third of these people live in Asia; just last year, 35 to 65 percent of the newborns tested in the provincial capitals of China showed iodine deficiencies.

Lack of iodine in the early stages of life impairs the development of the brain and certain other organs. Severe fetal iodine deficiency can cause cretinism, a condition that involves severe mental retardation and a stunted physique. Even a mild deficiency in early childhood can compromise intelligence; IQ tests have shown a 10 to 15 percent drop in expected scores among children with iodine-poor diets. The problem may also manifest itself in the deformity known as goiter - an enlargement of the thyroid gland, located at the base of the neck.

Although only a small amount of iodine is necessary for human health, many communities lack a source of the element in their local food supply. Coastal populations can often get their iodine from fish, but for people living in mountainous and flood-prone regions, meeting the dietary requirement can be harder because water run-off tends to leach iodine out of the soil. And some foods, such as cassava (a root crop grown throughout much of the tropics), actually inhibit absorption of the element.

Most countries facing widespread iodine deficiency have programs for distributing iodized salt, an approach supported by WHO, UNICEF, and the International Council for the Control of Iodine Deficiency Disorders, a research and development NGO that is a leading authority in the field. Salt is an easily distributed commodity and the cost of adding iodine to it comes to less than $0.10 per person per year. In some countries, other readily distributed foods are used for iodization; Australia, for instance, uses bread and Thailand uses fish paste. In parts of Asia and Africa, iodine is introduced directly into drinking water sources.

But ignorance can be as great a problem as lack of iodine itself. A 1991 survey in Cameroon, for example, found that one-third of the...