The harm of lead poisoning is mainly manifested in the lifelong damage to nervous system, blood system, cardiovascular system and skeletal system:
Lead has a direct toxic effect on specific nerve structures of multiple central and peripheral nervous systems. In the central nervous system, the cerebral cortex and cerebellum are the main target tissues of lead toxicity; In the peripheral nervous system, motor axons are the main target tissues of lead poisoning. Among them, the toxicity of lead to the nervous system is mainly manifested in the following four aspects: (1) It changes the psychology of patients with lead poisoning. Adults show depression, irritability and personality changes, while children show hyperactivity. (2) Lead poisoning can lead to mental decline, especially for children with learning disabilities. It is reported that the IQ of children with high lead is 4-6 points lower than that of children with low lead. (3) Lead poisoning can lead to sensory dysfunction. For example, many patients with lead poisoning will have visual dysfunction: retinal edema, retrobulbar optic neuritis, blind spots, abductor paralysis, optic atrophy, eye movement disorder, abnormal pupil accommodation, amblyopia or visual field changes; Or smell, taste disorders, etc. (4) The main effect of lead on peripheral nervous system is to reduce motor function and nerve conduction velocity, and muscle injury is one of the typical proofs of severe lead poisoning.
Lead has two main effects on the blood system, one is to inhibit the synthesis of hemoglobin, the other is to shorten the life of circulating red blood cells, which will eventually lead to anemia.
The damage of lead to cardiovascular system is mainly manifested in: (1) The mortality of cardiovascular diseases is closely related to the excessive lead in arteries, and the blood lead and 24-hour urine lead levels of patients with cardiovascular diseases are significantly higher than those of patients without cardiovascular diseases. (2) Lead exposure can cause hypertension. (3) Lead exposure can cause heart diseases and changes in heart function.
Bone is an important target organ system of lead toxicity. On the one hand, lead indirectly affects bone function and bone mineral metabolism by damaging endocrine organs; On the other hand, it poisons cells, interferes with basic cell processes and enzyme functions, changes the coupling relationship between osteoblasts and osteoclasts, affects the calcium system, and directly interferes with the function of bone cells.
This shows that the harm of lead poisoning is serious, so the prevention and detection work becomes very important. However, the symptoms after lead poisoning are often very hidden and difficult to find, so the most reliable method at present is blood test.
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Lead is a heavy metal element that seriously harms human health. It can affect nervous system, hematopoietic system, digestive system, urinary system, reproductive development, cardiovascular system, endocrine system, immune system, bones and other organs. The main target organs are nervous system and hematopoietic system. What is more serious is that it affects the growth and intellectual development of infants, impairs brain functions such as cognitive function, neurobehavior, learning and memory, and even causes dementia.
The seriousness of lead poisoning in children in China.
The concept of lead poisoning has changed fundamentally, and people's attention has turned to subclinical asymptomatic lead poisoning. Blood lead levels that were once considered safe have been repeatedly proved to be harmful to children's health. The standard of lead poisoning in children has dropped from 600μg/L before 1970s to 100μg/L at present, and it is found that even if the blood lead level drops to 10μg/L, there is no safe threshold for lead. Lead exposure in early life not only harms children's intellectual and behavioral development, but also affects cardiovascular abnormalities and osteoporosis in adulthood.
A large number of studies at home and abroad show that the blood lead level of infants is significantly related to IQ. The World Health Organization reported in 1994 that when the blood lead level of children is 140μg/L, the IQ value will drop by 3-7 points. Every time children's blood lead level increases 100μg/L, their IQ drops 1-3 points on average. The problem of lead poisoning among children in developing countries is very serious. Blood lead screening of 22,000 children under 0/.2 years old in major cities of India showed that 5 1.4% of children's blood lead exceeded the toxic standard value1.000μ g/L; More than 40% school-age children in Mexico City have blood lead levels above100μ g/L. At present, the situation of lead poisoning among children in China is very serious. Investigation on industrial areas in Shenyang, Beijing, Xi, Shanghai, Fuzhou, Guangzhou and other big cities shows that 85% of children's blood lead level exceeds 100μg/L, and they are in a state of asymptomatic subclinical lead poisoning. According to the investigation of 1997- 1999 in some cities in China, 38.8% of urban children's lead poisoning exceeded the standard. According to this ratio, among the 330 million 14 children in China, more than 1 100 million people are threatened by lead poisoning. WHO 1999 calls on developing countries to take urgent measures to deal with the increasingly serious lead pollution.
The main problems existing at present
In recent years, scientists in China have made outstanding achievements in the research and prevention of lead poisoning, and are catching up with the international research trend. However, at present, there are few achievements in studying the environmental differences of lead poisoning in China from both macro and micro aspects. The research on environmental factors and human lead poisoning mechanism is not deep enough; China lacks new drugs suitable for the prevention and treatment of lead poisoning.
At present, the main problems are:
1. Lack of quantitative assessment of the main sources of lead pollution in China. Lead pollution and lead poisoning are serious and common in China, and air, water, soil and food are polluted to varying degrees. It has been known that besides industrial pollution, there are also important ways to cause harm, such as waste gas pollution of leaded gasoline, pollution of household environment by lead workers, coal pollution, indoor paint, school supplies, toys and food intake. However, at present, there is a special lack of research on the source and harm differences of lead in different regions, urban and rural areas and industrial and mining areas in China.
2. The mechanism of lead affecting children's intellectual development is not clear.
3. Drugs for preventing and treating lead poisoning lack more breakthroughs. At present, the main drugs for treating lead poisoning are calcium ethylenediamine tetraacetate (Ca-EDTA), Cape calcium (Ca-DTPA), sodium dimercaptosuccinate (NaDMS) and other compound lead expelling agents. However, these preparations have certain side effects and are not specific. At the same time, essential trace elements in the body, such as zinc, copper, manganese and iron, are also discharged. Because the early and middle symptoms of lead poisoning are not obvious, once lead accumulates, it is difficult to completely discharge it, causing irreversible tissue damage. Therefore, it is very necessary to treat asymptomatic lead absorption as soon as possible and prevent it. In recent years, aiming at low-level lead exposure, lead-expelling salts, nutritious lead-expelling drinks and lead-expelling teas have been developed at home and abroad, and the effects of some nutrients and trace elements on lead toxicity have been discussed, but no mature products have been developed so far. Therefore, it is urgent to develop an economical and effective drug for preventing and treating lead poisoning, which is suitable for early administration, with little side effects and convenient administration.
Therefore, in view of the existing problems, it is of great theoretical and practical significance to carry out environmental health risk assessment of lead pollution in China, explore the mechanism of lead affecting children's intellectual development, and study and popularize new drugs to prevent and treat lead poisoning.
Carry out health risk assessment of lead pollution areas in China, and strengthen the research on drugs for preventing and treating lead poisoning.
According to the characteristics of China's regional environment, it is necessary to study the potential impact of low-dose long-term exposure of lead in the environment on human body and the regional risks of exposure routes, explore the pathogenic mechanism of lead at the cellular and molecular levels, develop new drugs for the prevention and treatment of lead poisoning suitable for China's national conditions, and form independent intellectual property rights.
The main contents of the proposed study are:
1. Study on risk assessment of lead health hazards in regional environment
Quantitatively evaluate the main sources and historical changes of lead pollution in China, study the spread and exposure characteristics of lead from environment to human body in regional environment, explore the environmental conditions and changing trends of lead poisoning, quantitatively evaluate the main sources of lead pollution in China, pay special attention to the sources, exposure routes and harm differences of lead in different regions, urban and rural areas and industrial and mining areas, and analyze the regional differences of dose effects of lead poisoning, so as to provide scientific basis for the formulation of relevant standards and regulations for lead poisoning prevention and control.
2. Study on the pathogenic mechanism of environmental lead pollution.
To explore the pathogenic mechanism of lead at molecular and cellular level, and to deeply study the mechanism of lead affecting children's intellectual development. To study the mechanism of lead-induced synaptic plasticity, ion channels, receptors, transmitters and gene regulation. Including the effect of lead on synaptic plasticity of hippocampal neurons during development; Effects of lead on ion channel characteristics of hippocampal neurons during development: effects of lead on dynamic changes of neurotransmitters in brain during learning and memory: effects of lead on gene expression of calmodulin, protein kinase, nitric oxide messenger and glutamate receptor subunit; The mechanism of learning and memory function in children with lead injury: directly observe the changes of brain structure and function in children and its relationship with blood lead concentration in children.
3. Study on the application of new efficient lead displacement agent.
Simulate the peristalsis of human gastric juice and gastrointestinal tract, study the adsorption of lead by a new preparation for expelling lead, and explore the mechanism of expelling lead; Through animal experiments, the effects of the preparation on blood lead, bone lead, organ lead, organ coefficient, blood calcium and blood zinc in rats were observed, and the detoxification effect of the preparation on lead poisoning rats and its protective effect on the body were discussed. Carry out toxicological research and clinical trials, develop new and efficient drugs for the prevention and treatment of lead poisoning and promote their application.
Strengthen the comprehensive coordination of interdisciplinary departments and effectively promote the prevention and treatment of lead poisoning in children.
With the acceleration of industrialization and urbanization, the problem of lead poisoning is not only a medical problem, but also a social problem that everyone is very concerned about. To solve the problems related to health and environment, we must rely on the comprehensive coordination of many departments.
The above research problems are closely related to the national demand and the frontier of scientific research. Environmental factors are closely related to the pathogenesis of lead from the environmental-biological-cellular level. The study of environmental health risks and mechanisms is combined with the development and application of drugs to prevent and treat lead poisoning, which is an interdisciplinary intersection and combination. We should organize the cooperation of earth science, medicine, environmental science, chemistry and biology to promote the prevention of lead poisoning in children more effectively.
China Academy of Sciences is the earliest unit to study the relationship between environment and disease. Over the years, we have cooperated with China Academy of Medical Sciences, Chinese Academy of Preventive Medicine, medical colleges and local disease prevention and control research departments for a long time, and made great achievements in the research of endemic disease prevention and control. In the fields of geographical ecology of endemic diseases, geographical epidemiology, environmental etiology, subcellular-molecular biological pathogenesis of environmental life factors, medical geographical mapping, comprehensive prevention and control of economy and ecology, a team capable of macro-external environment-micro has been formed. This fully shows that only by strengthening the comprehensive coordination of interdisciplinary departments can we solve the problems of environment and health.