To be honest, lead poisoning in children usually does not have typical clinical manifestations. Sometimes even if a child’s blood lead is as high as 600 µg/L or more, it is not always detected by parents, teachers or clinicians, and is often missed or misdiagnosed. The exact blood lead level of a child can only be determined after the child is given a blood lead screening test (blood lead test). Of course, it does not mean that children with lead poisoning do not have clinical symptoms, in fact, when children’s blood lead level increases, there will still be some clinical manifestations: Nervous system: when children’s blood lead exceeds 30 micrograms/liter, IQ will start to decrease, the higher the blood lead level, the more the IQ will decrease, children’s IQ and blood lead level show an obvious negative correlation, when children’s blood lead level is higher than 300 micrograms/liter, children’s IQ When children’s blood lead level exceeds 50 micrograms/liter, most of them will be very lively, several children with high blood lead level will be moving around in my clinic, climbing up and down, turning around, and the faucet and door handle will be rattling, without a moment of peace, which will be in contrast with other director’s clinic; children will appear hyperactive and inattentive; with the increase of blood lead level, hyperactivity and inattentiveness will increase. As the blood lead level increases, the hyperactivity and inattentiveness will get worse and worse. Therefore, in my lead poisoning clinic, there is also the fact that when the blood lead level exceeds 50 micrograms/liter, the child’s memory will decrease and temper will become bad, and when the blood lead exceeds 200 micrograms/liter, the child will even show aggressive behavior, biting, hitting, impulsive and irritable; some studies show that when the child’s blood lead level exceeds 200 micrograms/liter in childhood, the crime rate will increase when the child grows up This is probably because lead damages the self-inhibiting function of the nervous system, causing children to be unable to control their emotions and behaviors, and to do things that are too aggressive and even cause crimes. When children’s blood lead level is higher than 700 micrograms/liter, a few children may have dizziness and headache, and poor sleep; when the blood lead level exceeds 900 micrograms/liter, they may even have convulsions, convulsions, and toxic encephalopathy; of course, all these symptoms are also very common among children with normal blood lead but other diseases. Digestive system: When children’s blood lead level rises to 200 micrograms, constipation will appear, and the proportion is about one-third or more; when the blood lead level is higher, not only some children’s constipation will worsen, but also some children will have diarrhea or alternate diarrhea and constipation; some children also have nausea, vomiting, poor appetite and other manifestations. When the blood lead level exceeds 400 micrograms/liter, some children will have abdominal pain, and when the blood lead is higher than 600 micrograms/liter, this abdominal pain will be aggravated, and even a few children will show abdominal colic, and the higher the blood lead level is, the more severe the symptoms will be. I have had cases of abdominal colic that almost led to surgical caesarean section. This is actually a clinical manifestation of lead poisoning. Hematopoietic system: When the blood lead level is higher than 150 micrograms/liter, it will affect the function of hematopoietic system, but it may not necessarily appear anemia; as the blood lead level increases, the effect of lead on hematopoietic system becomes more and more serious, and when the blood lead level of children exceeds 300 micrograms or 400 micrograms/liter, the anemia will be very obvious and serious. Immune system: Lead is also harmful to the immune system of human body. The increase of blood lead level will interfere with the immune function of children, leading to the decrease of resistance to diseases and easy to have infectious diseases and even repeated infections. Cardiovascular system: The blood pressure of people who are exposed to lead for a long time will increase, and the blood pressure of people who are occupationally exposed to lead is higher than those who are not exposed to lead, and children will also receive the effect, and this effect is currently observed to be manifested about when the blood lead level of children rises above 300 micrograms per liter. Of course, lead is a kind of heavy metal with strong accumulation, which has effects on multiple systems and organs of the whole body and is harmful, and it has the greatest impact on children aged 0-6 years, especially on the development of the nervous system of children. Therefore, we call children 0-6 years old as the high-risk group for lead toxicity. And at the same time, the clinical manifestations caused by lead exposure or lead poisoning are not specific, so the only way to identify which child has excessive blood lead levels is through blood lead testing (blood lead screening). Therefore, it is especially important to popularize blood lead screening for children. The United States and other developed countries have passed legislation to require children aged 0-6 to have their blood lead levels measured once a year. It is hoped that our country can also pass legislation or other local regulations with a view to achieving the goal that children aged 0-6 must be screened once for blood lead level; and for areas living in areas with lead pollution or bad living customs, including areas with developed economic conditions, it is hoped that every child aged 0-6 can be screened once a year for blood lead. It is hoped that every child aged 0-6 will have a blood lead screening once a year, so that children with excessive lead levels can be detected in time for timely intervention and treatment, and the harm caused by lead to children can be reduced to a minimum.