Environmental iodine in iodine deficiency disorders with a Sri Lankan example

Iodine is an essential element for human and other animal health and forms an important constituent of the thyroid hormones thyroxine (T4, also known as tetraiodothyronine) and triiodothyronine (T3). These hormones play a fundamental biological role controlling growth and development (Hetzel and Maberly, 1986). If the amount of utilisable iodine reaching the thyroid gland is inadequate, or if thyroid function is impaired, hormone production can be reduced resulting in a group of conditions collectively referred to as Iodine Deficiency Disorders (IDD) (Fernando et al., 1987; Hetzel, 1989). The World Health Organisation (WHO, 1993) estimate that in excess of one billion people world-wide are at risk from IDD, the most common manifestation of which is goitre (Figure 1). Iodine deficiency is the world’s most common cause of preventable mental retardation and brain damage, and has a significant negative impact on the social and economic development of communities.