A:
The brain center and peripheral nervous system are damaged, which leads to hyperactivity, inattention, learning difficulties, willful impulsiveness and irritability;
Destroy the hematopoietic system, hinder heme synthesis, and lead to anemia;
Affect the function of digestive system, leading to anorexia, pica, loss of taste or confusion in children;
Inhibit the synthesis and release of growth hormone, so that children's development is delayed;
Suppress the immune system function, make children's physique poor, and increase the chances of catching a cold and infection;
Affect the body's absorption and metabolism of other metal elements, resulting in ineffective or less absorption of iron, zinc and calcium;
It does great harm to reproductive organs, especially kidneys, resulting in renal insufficiency.
It affects the normal operation of the heart and causes myocardial damage.
What harm does lead do to the cranial nerve system?
A: Lead is neurotoxic, which has direct and obvious damage to the central nervous system and peripheral nervous system of children, especially infants. The neurotoxic effect of lead often shows obvious subclinical stage before clinical manifestations, which is harmful to children's intellectual and behavioral development.
(1) Lead poisoning can damage children's intelligence.
The damage of lead poisoning to children's nervous system began in the fetal period.
Foreign studies have found that the higher the lead concentration in pregnant mothers, the lower the children's perception, language ability and memory ability. Lead in the mother can easily enter the fetus through the placenta. Immature fetal brain endothelial cells can't prevent lead from entering brain tissue, which leads to lead poisoning in the fetus before it matures. For every 0.48μmol/L increase in maternal blood lead, children's IQ drops by 2 points. (Note: 100 μ g/L = 10 μ g/L =0.483 μ mol/L)
Damage of lead to children's intellectual development
Long-term exposure of children to low concentrations of lead will lead to the decline of children's IQ and learning difficulties.
Studies at home and abroad show that for every 0.483μmol/L increase in blood lead, IQ drops by 6-8 points on average. (Note: 100 μ g/L = 10 μ g/L =0.483 μ mol/L)
Professor Ruan, School of Life Sciences, University of Science and Technology of China, etc. The effect of heavy metal lead on children's learning and memory and its cellular and molecular mechanism were studied. The results showed that the blood lead level of children was negatively correlated with IQ. The researchers measured the blood lead level of 69 new young students in HKUST, and found that their average blood lead level was far below the poisoning standard and the blood lead range of most children in China, while their IQ was far higher than that of children of the same age. (Article source "China Education News")
(2) Lead changes the psychology and behavior of lead poisoning patients.
Can cause children: hyperactivity, impulsiveness, inattention, increased aggression, depression and irritability.
The meeting of the American Academy of Pediatrics pointed out that previous similar studies also confirmed that lead poisoning may lead to people's antisocial behavior or grumpy personality. Reducing lead poisoning in people's bodies may be the most effective way to prevent crime. The University of Pittsburgh studied the lead content of more than 400 teenagers in Pennsylvania. The results show that more than 85% of criminals have extremely high lead content. The lead content in the bones of male teenagers who have committed crimes is almost twice that of teenagers who have not committed crimes, and the proportion of women is more than twice.
(3) Lead poisoning can cause sensory dysfunction.
Children with lead poisoning may have visual dysfunction and amblyopia symptoms.
(4) The main effect of lead on peripheral nervous system is to reduce motor function and nerve conduction velocity.
Children with severe lead poisoning will appear: poor balance and dyskinesia.
What harm does lead do to blood circulation?
A: The mechanism and process of human hematopoiesis are shown on the right.
The influence of lead on children's hematopoietic system is mainly to interfere with the metabolism of protoporphyrin and inhibit the enzymes that promote heme synthesis. Fe ~ (2+) can't bind with protoporphyrin, and Fe ~ (2+) has no binding target, so it can't make blood, thus causing anemia in children.
The symptoms of this anemia are similar to iron deficiency anemia, so some parents mistakenly think it is iron deficiency anemia, and the anemia has not improved after long-term iron supplementation.
This happens when blood lead exceeds 0.4 mg/L.
What harm does lead do to the immune system?
A: Lead will weaken the body's resistance to pathogenic microorganisms and increase susceptibility. The main reason is that lead inhibits the function of T cells and greatly weakens their immunoregulation ability, as shown in the schematic diagram:
What harm does lead do to the digestive system?
A: The digestive tract mucosa has the ability to secrete lead. In the process of lead secretion, lead directly acts on gastric mucosa, destroying its regenerative ability and causing inflammatory changes of gastric mucosa. The detection rate of pathological damage of gastric mucosa in patients with chronic lead poisoning is 96.7%, and atrophic gastritis and atrophic gastritis with overgrowth can occur.
Lead can inhibit the activity of various enzymes in intestinal wall, make smooth muscle spasm and cause abdominal pain, which is a common lead colic. Taiyuan City, Shanxi Province, China, has treated many patients with lead colic caused by lead poisoning.
The common symptoms of digestive system caused by lead poisoning in children include anorexia, nausea, vomiting, dyspepsia, abdominal pain, diarrhea, constipation, pica and so on.
What harm does lead do to growth and development?
A: Lead poisoning will affect children's physical development.
(A) affect the metabolism of growth hormone
Thyroid gland is the largest endocrine gland in human body, which synthesizes and secretes thyroxine and promotes the metabolism of substances and energy in the body (promoting growth and development). The function of thyroid gland to synthesize and secrete thyroxine is controlled and regulated by two parts, one is thalamus and the other is pituitary. Lead can inhibit these two parts and hinder the physiological function of thyroid gland, that is, affect the synthesis and release of growth hormone, thus delaying physical development.
(B) directly affect bone growth
More than 90% of lead in the body is accumulated in bone tissue, and the accumulation of bone lead begins in the fetal period, and then gradually increases with age, which can last for about 50 years. Excessive lead accumulation in long bone tissue directly affects bone growth.
(3) indirectly affect bone growth
Lead affects the level of vitamin D3 by changing the level of circulating hormones, and indirectly affects bone growth.
(4) Lead directly affects or replaces the deposition of calcium in bones, thus affecting the growth of bones.
Domestic research also shows that with the increase of children's blood lead concentration, the average value of their height, weight and chest circumference tends to decrease. Every increase in blood lead 100 μ g/L will reduce the possibility of height1.3c..
Effect of lead on macro/trace element metabolism?
A: In the human body, calcium, iron, zinc and lead all exist in ionic state. The activity of lead is much higher than that of calcium, iron and zinc, that is, the binding ability of lead to human cells is much stronger than these metal ions. Therefore, when lead poisoning enters children's bodies, it will take the lead to seize the position of calcium, zinc and iron plasma, obviously hinder their absorption, function and metabolic activities, and affect children's physical growth and intellectual development.
Therefore, there is a saying in the field of trace element research: "Supplementing calcium and zinc without discharging lead is a waste of money."
What harm does lead do to cardiovascular system?
A: The damage of lead to the cardiovascular system is mainly manifested in three aspects:
(1) The mortality of cardiovascular diseases is closely related to the excessive lead in arteries. The levels of blood lead and 24-hour urine lead in patients with cardiovascular diseases were significantly higher than those in patients without cardiovascular diseases.
(2) Elevated lead level can cause hypertension.
(3) Elevated lead levels can cause heart diseases and changes in heart function.
What harm does lead do to pregnancy?
A: Studies have shown that lead has strong reproductive toxicity, embryonic toxicity and teratogenicity. Even low-level lead exposure may still affect the growth and development of intrauterine fetus, leading to malformation, premature delivery and low birth weight.
During pregnancy, a large amount of bone lead will be released in women. This is because the metabolic pathways of lead and calcium in the body are very similar. The mother increases the absorption and mobilization of lead, and at the same time increases the absorption of calcium in the intestine and the movement of calcium in the bones. In order to meet the needs of fetal development and bone calcification in the second and third trimester of pregnancy, the transport of lead from mother to child will also increase. The transport of lead from mother to fetus occurs at the beginning of placenta formation, and may even begin before the establishment of placental circulation.
(A) the impact of lead on the value of embryos
High level of lead can inhibit embryo implantation, the adhesion and development ability of blastocyst will decrease with the increase of lead concentration in the culture medium, the division of embryonic cells will be inhibited, the level of pregnancy-related joint hormones in plasma will be significantly lower than normal, trophoblast cells will not be adsorbed on the endometrium, and the response of uterine steroid hormone receptors to ovarian sterol hormones will be inhibited.
(2) that effect of lead on fetal survival and teratogenesis.
An embryo or fetus is exposed to large doses of lead. It can cause abortion, stillbirth, stillbirth and deformity.
(c) Effects of low-level lead exposure during pregnancy on fetal growth and development
1, maternal blood lead level and infant umbilical cord blood lead level have obvious positive correlation with the occurrence of premature rupture of membranes.
2. Low-level lead exposure during pregnancy will increase the chance of premature delivery.
3. Many studies show that lead exposure will shorten the gestational age. Every time maternal blood lead level increases 1 logarithmic unit, the gestational age will be reduced by 0.46 weeks, while umbilical blood lead level will increase 100/L, and the gestational age will be shortened by nearly 1 week.
4. Influence on birth weight, body length and head rotation.
Prenatal lead exposure will reduce the baby's birth weight. Every 0.048u mol/L increase in umbilical cord blood lead level will reduce the birth weight by 3g. Every time the prenatal blood lead level increases 1 natural logarithmic unit, the birth weight will decrease 1 14g. Every 0.483 μm ol/L increase in cord blood lead level will reduce the baby's birth weight by 300g g, and every 0.483 μm ol/L increase in cord blood lead level will reduce the baby's body length by 2.5cm.
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