On March 11th Japan experienced a devastating earthquake followed by a tsunami resulting in catastrophic damsge and loss of life.This natural disaster in turn caused a Inanmade disaster by severely damaging four nuclear reactors with the ongoing release of radioactivity.Of particular concern is iodine(I)-131,the unstable,radioactive isotope of iodine.Normally,stable iodine is an essential element for the thyroid gland to produce thyroid hormone that is required for the optimal development of the human brain.As a result,brain damage from iodine deficiency in the fetus and developing child is the leading cause of preventable mental retardation。