Define Causes of iodine deficiency disorders?

We have studied above that iodine deficiency is a naturally occurring ecological phenomenon that is present in many parts of the world. The main cause of iodine deficiency in soils is leaching by floods or high rainfall. Mountainous regions including the Himalayas therefore have some of the highest prevalence of iodine deficiency. Iodine deficiency also occurs due to flooding. In areas of endemic iodine deficiency, the water and foods (plants and animals grown there) have low iodine content.