China stipulates that children’s blood lead below 100 micrograms/liter is an acceptable level, and when it reaches 450 micrograms/liter or more, it is severe lead poisoning. Before the 1970s, the international medical community generally believed that the blood lead concentration reached 600 micrograms/liter or more, and children showed symptoms such as anemia, colic and convulsions before they could be diagnosed as lead poisoning like adults. Studies in the 1980s showed that blood lead at around 100 micrograms/liter, although not so much as to produce obvious clinical manifestations, may produce some damage to children’s intellectual development, physical growth and hearing. Therefore, the CDC revised the diagnostic criteria for childhood lead poisoning to greater than or equal to 100 micrograms/liter in 1991. In other words, as long as the blood lead level of children exceeds or equals to 100 micrograms/liter, regardless of the corresponding clinical symptoms, signs and biochemical changes, children can be diagnosed with childhood lead poisoning. 2012, the U.S. revised the standard for childhood lead poisoning to 50 micrograms/liter. At the same time, it is emphasized that children under 6 years old must undergo annual blood lead screening. China has carried out research and prevention of childhood lead poisoning in some areas since the 1980s, and has made useful exploration to reduce the prevalence of childhood lead poisoning in China by drawing on foreign experience. In February 2006, the former Ministry of Health of the People’s Republic of China published the Guidelines for the Prevention of Childhood Hyperleademia and Lead Poisoning and the Principles for the Classification and Treatment of Childhood Hyperleademia and Lead Poisoning (for trial implementation), which were proposed by domestic experts and are in line with China’s national conditions, stipulating the diagnostic criteria and classification of childhood lead poisoning in China. Considering that the term “poisoning” is easily ambiguous to the public, China also innovatively introduced the term “hyperleademia” to define the group of children with blood lead level between 100 and 199 micrograms/liter, and set the diagnostic standard of “childhood lead poisoning” as “childhood lead poisoning”. The diagnostic criteria for “childhood lead poisoning” is defined as blood lead level higher than or equal to 200 micrograms per liter.