Iodine deficiency is the invisible killer of intelligence. According to Professor Shu Yanqing, deputy head of the expert advisory group on iodine deficiency disorders of the Ministry of Health, iodine deficiency disorders are the symptoms of iodine malnutrition caused by iodine deficiency in the natural environment, which are not only manifested as endemic goiter, cretinism, simple deafness, abortion, premature delivery and congenital malformation, but also the main harm is that iodine deficiency affects the brain development of the fetus, leading to mental and physical development disorders of children and intellectual damage to people in iodine-deficient areas. China is one of the countries with the most serious prevalence of iodine deficiency disorders in the world. 1993 It is estimated that more than 700 million people live in iodine deficiency areas. It is precisely because of the widespread distribution of iodine deficiency disorders and the large number of victims that it seriously harms the quality of the population and social and economic development. Therefore, iodine deficiency disorders have now risen from a single disease to a serious public health problem. Iodization of salt is the best intervention measure. Iodine deficiency in natural environment actually refers to iodine deficiency in soil and water. Professor Shu Yanqing said that it will take about 1 1,000 ~ 20,000 years for iodine in soil to be replenished through atmospheric circulation, but the degradation of natural environment and human factors are still causing iodine deficiency in soil. Therefore, it is impossible to change the iodine deficiency in the environment through "natural correction". Once the natural environment is short of iodine, it will exist for a long time. The only way is through human intervention. Professor Ling Jiesheng, chairman of the International Council for the Control of Iodine Deficiency Disorders, said that nearly a hundred years of history has proved that iodizing salt is the most effective way to control and eliminate iodine deficiency disorders. Up to now, the coverage rate of iodized salt in more than 30 countries around the world has reached 90%, and more than 70% of the global population is eating iodized salt. Shu Yanqing said that with the comprehensive implementation of comprehensive prevention and control measures focusing on iodized salt, the consumption rate of iodized salt among China residents has continued to increase, and the iodine nutrition level has improved significantly. From June 5, 2000 to 10, the Ministry of Health announced that China had achieved the phased goal of eliminating iodine deficiency disorders. The national monitoring results of iodine deficiency disorders in 2002 showed that the achievement of basically eliminating iodine deficiency disorders in China was further consolidated, and the iodine nutrition level of the population in China was basically appropriate and more reasonable. According to experts, in the process of promoting iodized salt in China, two groups of people are fully considered, namely, people in areas with high iodine content and people who are not suitable for iodized salt because of treating diseases (such as thyroid diseases). The Regulations on the Administration of Iodized Salt for Eliminating the Harm of Iodine Deficiency Disorders clearly stipulates that these two groups of people can buy non-iodized salt in shops specially set up by the salt industry department. At present, there are hundreds of non-iodized salt outlets in big cities such as Beijing and Shanghai, and citizens can buy them according to their own needs or with hospital certificates. However, experts believe that from a nationwide perspective, iodized salt will remain compulsory for a long time to come, and it cannot be completely freely chosen by diners like the developed countries such as the United States and Canada, which is determined by the actual situation facing the prevention and treatment of iodine deficiency disorders in China. Professor Yan from the Institute of Endocrinology of Tianjin Medical University said that iodine deficiency in the environment is an objective fact that cannot be changed. Once qualified iodized salt is stopped, iodine deficiency disorders will come back. According to the monitoring results in 2002, although the coverage rate of iodized salt reached over 90% in 26 provinces at the provincial level, it was found that the non-iodized salt rate was still higher than 10% in 22 provinces during regional monitoring. Experts believe that residents' concerns are actually unnecessary. Since the implementation of the comprehensive prevention and control strategy based on iodized salt, China has established and continuously improved the iodine nutrition monitoring system and information feedback mechanism, and relevant departments have adjusted the prevention and control strategy in time according to the monitoring feedback information and expert argumentation opinions. For example, according to 1995 national monitoring results of iodine deficiency disorders, it was found that the concentration of some iodized salt samples was too high, and 1996 set the upper limit value of salt iodine concentration in time. The monitoring in 1997 found that children's urinary iodine value was too high, which was the result of improper abuse of iodized oil pills and iodine-containing health products in many areas. The Ministry of Health stopped this unhealthy phenomenon in time and put forward the slogan of "scientifically supplementing iodine" and a series of intervention measures. From 65438 to 0999, according to the monitoring information, the state adjusted the concentration of iodized salt to ensure the proper iodine nutrition level of the population.