Salt, also known as table salt, of human existence is one of the most important matter, is also the most commonly used seasoning in cooking. The main chemical composition of salt sodium chloride ( chemical formula NaCl ) in salt content of 99%, part of the region produced salt potassium chloride is added to reduce the content of sodium chloride in order to reduce the incidence of hypertension. While most parts of the world by the addition of iodine to salt for preventing iodine deficiency disease, added iodine salt called iodized salt. In March 11, 2011, Japanese Benzhoudao Sea earthquake triggering nuclear explosion, China Guangdong many residents appear to prevent nuclear radiation and buying salt phenomenon. Guangdong Province CDC experts said, eat salt radiation that is reliable, people do not believe the rumor.