The ideal blood lead level should be zero, but blood lead in the body is often not zero due to environmental contamination. The U.S. National Center for Disease Control (CDC) defined a blood lead mass concentration of ≥100 mg/L as childhood leadpoisoning in 1991. In 2006, China adjusted the diagnostic criteria of childhood lead poisoning, put forward the concept of hyperleademia, and formulated the intervention and treatment program of lead poisoning. 1.Harm of lead poisoning and the current situation The harm of lead poisoning to children is a dose-effect continuous process, which involves the whole body multi-systems such as neurology, blood, digestion, urinary, immunity and endocrine and affects the growth and development. Nevin confirmed that crime rates in nine countries, including the United States, were positively correlated with blood lead levels in preschool children. FLeece et al. reported a case of neonatal lead poisoning encephalopathy due to prenatal lead exposure. Low-income earners, children’s toys and renovation of old cities increase the chance of childhood lead poisoning. However, with the emphasis on environmental protection in various countries, the average blood lead level in children has shown a significant downward trend except for a few industrial pollution areas. At present, the average blood lead mass concentration of children in most cities in China is 50-90mg/L, among which the proportion of >100mg/L is 10%-40%, while the proportion of ≥200mg/L is less than 2%, and the proportion of those who need to be treated with drugs for lead expulsion is even lower. 2.The manifestation of lead poisoning 2.1 The clinical manifestation of acute or subacute poisoning is metallic taste in the mouth, salivation, vomiting (vomit is white milk lump-like), severe abdominal pain. The terminal sensation of the extremities is reduced and lead paralysis may appear. In the case of lead poisoning encephalopathy, severe headache, convulsions and even coma may appear. 2.2 The response to lead exposure in chronically poisoned children is not linearly related to blood lead level and is mostly non-specific. It is mostly seen in children after 3 years old. The general time from lead exposure to the appearance of symptoms is 3 to 6 months. It can affect children’s psychology, behavior and immunity, with dizziness and general weakness being the most obvious. Poor appetite, abdominal pain, diarrhea or constipation may occur. Dwarfism, hyperactivity & learning disabilities. There are black lead lines on the edge of the gums, gray face (lead appearance), and hypochromic normal red blood cell type anemia. 3.Diagnosis of lead poisoning 3.1 Diagnostic criteria: CDC defines blood lead mass concentration ≥100mg/L as childhood lead poisoning, and this is still the intervention standard abroad. 2006 China’s criteria for hyperleademia: 2 consecutive venous blood lead mass concentrations ≥100mg/L and <200mg/L; criteria for lead poisoning: 2 consecutive venous blood lead mass concentrations ≥200mg/L, and according to The blood lead level is divided into mild, medium and severe lead poisoning. 3.2 Grading diagnosis: China's grading is ≥100ug/L and <200mg/L for hyperleademia; ≥200mg/L and <250mg< span="">/L for mild lead poisoning; ≥250mg/L and <450mg/L for moderate lead poisoning; ≥450mg/L for severe lead poisoning. The CDC classifies blood lead levels into 5 levels: Level I <100mg/L; Level II-A ≥100mg/L and <150mg< span="">/L; Level II-B ≥150ug/L and <200ug/L; Level III ≥200ug/L and <450ug< span="">/L; Level IV ≥450ug/L and <700ug< span="">/L. Level I is currently considered a relatively safe blood lead level, while levels II-V are different degrees of lead poisoning. 3.3 Measurement methods and selection of specimens: The methods of blood lead determination include nuclear dilution mass spectrometry, atomic absorption spectrometry and electrochemical method. The former is the most accurate, but the equipment requirement is high and expensive, so it is usually only used for research work; while the latter two have no advantages and disadvantages, the key is the quality control of the determination process. According to the different methods of specimen collection, there are venous blood lead, peripheral capillary blood lead and paper method blood lead, the latter two can only be used as screening methods, but not as the basis for diagnosis and treatment. Dental lead and hair lead have only research value but no practical application value due to the high technical requirements of measurement. Protoporphyrin and zinc porphyrin are no longer used as screening indicators for childhood lead poisoning. 4.Treatment of lead poisoning 4.1 Treatment principle: According to the literature, the treatment of high leademia and mild lead poisoning is to get away from the source of lead pollution, health guidance and nutritional intervention, and generally no need of lead repellent drug treatment, or appropriate Chinese medicine such as Qizao Oral Liquid, Zhiqi Granules and Qianguohua. Moderate and severe lead poisoning needs to be treated with chelating agent to expel lead. 4.2 Lead repellent treatment: Dimercaptosuccinic acid (DMSA) is preferred for treatment. Usage: 350mg/m2(body surface area) or 10mg/(kg?d) per time, 3 times daily orally for 5d, and then change to twice daily with the same dosage for 14d. Each course of treatment is 19d in total. m2 (body surface area), intravenous or intramuscular injection, 5d for a course of treatment. If the blood lead is ≥450ug/L, the above treatment plan can be repeated; if the blood lead is <450ug/L and ≥250ug/L in 2 consecutive reviews, it is treated as moderate lead poisoning. If the blood lead mass concentration is ≥700ug/L, venous blood lead should be rechecked immediately and hospitalized in a hospital capable of treatment immediately after confirmation. According to the medical history of the child, the oral intake should exclude a large amount of lead pollutant mercaptan residue in the gastrointestinal tract, and give enema and gastric lavage if necessary. Combined treatment with DMSA and edetate calcium sodium is used. The combined treatment should be treated with DMSA for 4h, and edetate sodium should be used only after the child appears to urinate, otherwise it will lead to lead poisoning encephalopathy. During the treatment period, liver and kidney function, water electrolytes and other indicators should be tested. The blood lead should be rechecked at the end of the combined treatment, if it is ≥700ug/L, the combined treatment program can be repeated immediately, if it is ≥450ug/L, it will be treated as severe lead poisoning. After 3 courses of continuous lead expulsion treatment, the level of iron, zinc, calcium and other trace elements in blood should be checked and supplemented in time. And closely observe the treatment effect. There is not much experience in the treatment of neonatal lead poisoning. The author's department has treated one case of neonatal severe lead poisoning (blood lead mass concentration 600ug/L) with sodium dimercaptopropane sulfonate (Na-DMPS), with satisfactory efficacy and no obvious side effects. 5.Prevention of lead poisoning Hyperleademia and lead poisoning in children are completely preventable. Lead dust in the environment is the main source of lead poisoning in children. Children's food and tableware should be covered with dust. Ensure children's dietary balance and the supply of various nutrients, and educate children to develop good eating habits. Nowadays, the proportion of children with blood lead concentration ≥200ug/L in urban and rural areas in China is very low, so it is generally not necessary to do blood lead screening. 1-2 years old children and children with high risk factors of lead poisoning are the focus of screening. Through environmental intervention, health education, focused screening and monitoring, we can achieve the purpose of prevention, early detection and early intervention of childhood lead poisoning.