Iodine deficiency diseases are a group of diseases that are or can be caused by a lack of iodine in the body. Iodine is a dark purple nonmetallic element that belongs to a halogen group but is less reactive than other halogens. It has a boiling point of 13.5ºC and a melting point of 183ºC, when heated a purple vapor is released. It can be extracted from seawater, algae and oil well brines. It is also concentrated in the thyroid gland as part of the thyroid hormone. Iodine can be found more in water than on land, because the iodine cycle is very slow and incomplete in most areas, so it takes a long time for soil to recover iodine (Michael Zimmermann & Creswell J. Eastman, 2009). ), which is removed from the soil by processes such as leaching and continued erosion. Thus, crops grown on such soils become iodine deficient. Washed-up iodine usually ends up in seawater, resulting in iodine-rich areas (World Health Organization, 1995) and areas of frequent flooding, but can also occur in coastal regions (Michael Zimmermann & Creswell J. Eastman, 2009). Iodine is necessary for growth and development, even for the fetus. Lack of iodine is also known as iodine deficiency and can cause stillbirth, mental retardation, failure to thrive, and goiter. Humans need a very small amount of iodine to prevent deficiency (World Health Organization, 1995). According to the WHO book, humans only need 250 micrograms of iodine, or only a quarter of a milligram (World Health Organization, 1995). This small amount is able to nourish humans and help them stay healthy. The tables below show the recommended daily intake of iodine per day. Table 1: World Health Organization Recommendation...... middle of article......m-topic-overview ?page=2Healthwise. (July 16, 2010). Hypothyroidism Underactive thyroid. Retrieved August 20, 2012 from Web MD: http://www.webmd.com/a-to-z-guides/hypothyroidism-underactive-thyroid-symptoms-causes-treatmentsHealthwise Staff, Romito, K. and KIm, MI (7 August 2012). Hypothyroidism. Retrieved from UW Health: http://www.uwhealth.org/health/topic/major/hypothyroidism/hw145667.htmlHealthwise Staff, Thomson, E. and Lau, DC (August 4, 2011). Hyperthyroidism. Accessed November 2012 from UW Health: http://www.uwhealth.org/health/topic/major/hyperthyroidism/hw149039.html#sec-hw149039-HealthToolsMichael Zimmermann, M. and Creswell J. Eastman, M. (2009, September 1). Disorders due to iodine deficiency. Retrieved May 28, 2012 from Thyroid Disease Disorders: http://www.thyroidmanager.org/chapter/the-iodine-deficiency-disorders/Ministry of Health. (2012).