The human brain, hippocampus and cerebral cortex are the main target tissues of lead toxicity and the central nervous system with abundant blood vessels. The blood-brain barrier is an important defense structure that prevents lead from entering the nervous system and avoiding neurotoxic effects. Because the development of children’s blood-brain barrier is not yet complete, the chance of lead poisoning has greatly increased. Scientific practice has proved that:
1. The absorption rate of lead in children and the retention time in the body are 5 to 8 times that of adults. Lead is absorbed more in the body but less excreted.
2. The lead in the storage pool has high fluidity and is easier to move into the blood and soft tissues, so the probability and degree of endogenous lead exposure is higher.
3. Lead is a pro-neurotoxic toxicant, which can easily penetrate the undeveloped blood-brain barrier of children and cause damage to the children's brain.
4. Lead can inhibit the absorption of calcium, zinc and iron, reduce the synthesis of heme, damage the body's immune system, and destroy the function of cellular immunity and phagocytes.