What are the Symptoms of Lead Poisoning?

Lead is absorbed in the ionic state and enters the blood circulation. It is mainly distributed in various tissues of the body in the form of lead salts and plasma proteins. About 95% of lead is deposited in the skeletal system and hair in a few weeks. About 95% of the lead in the blood is distributed in red blood cells, mainly in the red blood cell membrane, and plasma only accounts for 5%. Lead phosphate deposited in bone tissue is stable and maintains a dynamic balance with lead in blood and soft tissues. The absorbed lead is mainly excreted through the kidneys, and can also be excreted through feces, milk, bile, menstruation, sweat glands, saliva, hair, nails, etc. ^[1]

Chronic lead poisoning

Chronic lead poisoning is a non-communicable chronic disease caused by the cumulative absorption of lead. Typical symptomatic lead poisoning in children is not common. Although most children do not show signs of cerebral lesions, they have persistent behavior and cognition Problems that seriously affect health and learning. When it shows irritability, no appetite, personality change, abdominal cramps and other symptoms, its blood lead content is generally about 50 g / dL, which is already a severe lead poisoning.

Overview of chronic lead poisoning

Lead is absorbed in the ionic state and enters the blood circulation. It is mainly distributed in various tissues of the body in the form of lead salts and plasma proteins. About 95% of lead is deposited in the skeletal system and hair in a few weeks. About 95% of the lead in the blood is distributed in red blood cells, mainly in the red blood cell membrane, and plasma only accounts for 5%. Lead phosphate deposited in bone tissue is stable and maintains a dynamic balance with lead in blood and soft tissues. The absorbed lead is mainly excreted through the kidneys, and can also be excreted through feces, milk, bile, menstruation, sweat glands, saliva, hair, nails, etc. ^[1]

Pathophysiology of chronic lead poisoning

Causes of chronic lead poisoning

I. Absorption, distribution and elimination of lead Normal people enter 300 g of lead daily from the diet, about 10% of which can be absorbed, and about 40% of the lead inhaled by the respiratory tract can be absorbed. After the lead is absorbed, it enters the blood and is distributed in soft tissues. Such as liver, spleen, kidney, brain, etc. Later, lead is redistributed in the body,

Virus factor

90% to 95% of lead is stored in the bones. Lead absorbed into the body is mainly excreted by the kidneys, and a small part is excreted by feces, saliva, sweat, milk, etc. Accumulation of more than 0.5mg of lead per day can accumulate and appear toxic. Lead in blood and soft tissue is transportable lead, which is biologically active. Its amount exceeds normal, but lead is absorbed when there are no symptoms of poisoning. Excess lead can cause toxicity. Lead in bone is stored lead, no biological activity, blood lead, Lead in soft tissue is in a state of dynamic equilibrium with lead in bones. In the case of infection, drinking, acidosis, etc., lead transport in bones to blood and soft tissues can cause poisoning.

Chronic lead poisoning

Poisoning mechanism The toxicity of lead and its inorganic compounds is related to the amount of lead in the body. Lead compounds with small particles are easily inhaled by the respiratory tract. Lead compounds with a high concentration of solubility are easily absorbed into the body, so they are more toxic. Lead is easily associated with the thiol groups of proteins in the body. In combination, it can inhibit thiol-containing enzymes, especially several enzymes related to heme synthesis. Lead inhibits -amino-r-ketovalerate dehydratase (ALAD) in red blood cells, which increases -amino-r-ketovalerate (ALA) in serum and urine. Lead inhibits fecal porphyrinogen decarboxylase, causing feces in urine. Increased porphyrin, lead inhibits heme synthetase, interferes with the combination of iron and protoporphyrin to heme, and affects the production of hemoglobin. As a result, iron is accumulated in the erythrocytes (forming cyclic iron granulocytes) and free protoporphyrin (FEP ), Free protoporphyrin chelate with zinc to form zinc protoporphyrin (ZPP).

Lead poisoning can be seen in the increase of rainbow cells. This is because lead inhibits the red blood cell pyrimidine-5-nucleotide plum, which impedes the degradation of pyrimidine nucleotides in red blood cells, and also hinders the degradation of ribosomal RNA. Degraded pyrimidine nucleotides and ribosomal RNA, forming basophilic dots.

Lead is attached to the membrane of red blood cells, which interferes with Na + and K + ATPases, increases the fragility of red blood cells and is easily hemolyzed.

In recent years, it has been found that ALA can cross the blood-brain barrier. A large amount of ALA entering the brain tissue can cause various behavioral and neural effects during lead poisoning. The mechanism may be that ALA and r-aminobutyric acid (GABA) have similar structures and can compete with GABA for the postsynaptic membrane. GABA receptors affect the function of GABA.

Signs and symptoms of chronic lead poisoning

Chronic lead poisoning nervous system

Mainly manifested as neurasthenia, polyneuropathy and encephalopathy. Deficiency, one of the early and more common symptoms of lead poisoning, manifested as dizziness, headache, general weakness, memory loss, sleep disturbance, dreaminess

Unconscious patient

Among them, dizziness and general weakness are the most obvious, but they are generally mild and are functional symptoms.

Polyneuropathy can be divided into sensory, motor, and mixed types. The sensory type manifested as numbness of the extremities and glove-sock type sensory disturbance of the extremities.

Encephalopathy is the most severe lead poisoning. Symptoms include headache, nausea, vomiting, high fever, irritability, convulsions, drowsiness, mental disorders, coma and other symptoms, similar to seizures, meningitis, cerebral edema, psychosis or local brain damage syndromes.

Chronic lead poisoning digestive system

Mild cases show general gastrointestinal symptoms, and severe cases show abdominal cramps.

Gastrointestinal symptoms include metallic taste in the mouth, loss of appetite, bloating and discomfort in the upper abdomen, abdominal pain and constipation, dry stools in the form of abacus beads, and refractory constipation before the onset of lead colic. Abdominal colic is a sudden onset, mostly around the umbilical cord, with paroxysmal aggravation of persistent pain, each attack from several minutes to several hours. During the examination, the abdomen was flat and soft, with mild tenderness, no fixed tenderness point, decreased bowel sounds, and often accompanied by temporary elevated blood pressure and fundus arterial spasm.

Chronic lead poisoning blood system

The main reason is that lead interferes with the hemoglobin synthesis process and causes changes in its metabolites, leading to anemia, mostly hypopigmented normal red blood cell anemia.

Diagnosis of chronic lead poisoning

Determination of lead in humans with chronic lead poisoning

(1) Blood lead is an absorption index before the near term. The upper limit of the normal value of blood lead is 2.4 mol / L (50 g / dl).

(II) Urine lead can reflect the absorption of lead. The upper limit of the normal value of urine lead is 0.39mol / L (0.08mg / L).

(3) Diagnostic urine lead test: 1.45 mol / L (0.3mg / L) of urine lead is the upper limit of normal value, and urine lead exceeds 3.86 mol / L (0.8mg / L) or 4.82mol / L (1mg / d) Can diagnose lead poisoning.

(4) Fecal porphyrin in urine (urinary brown pigment) The increase of fecal porphyrin in urine is also seen in hematoporphyrin disease, liver disease, alcoholism and barbiturate poisoning. Fecal porphyrin in urine is positive for semiquantitative ++.

(5) Both erythrocyte free protoporphyrin (FEP) and erythrocyte zinc protoporphyrin (ZPP) are sensitive indicators reflecting lead absorption. ZPP is measured with a blood fluorometer, which is fast and convenient for on-site inspection. The normal upper limit of FEP is 0.72-1.78 mol / L (40-100 g / dl). The upper limit of the normal value of ZPP is 0.9-1.79 mol / L (4.0-8.0 g / gHb). The increase in both is also seen in iron deficiency anemia.

(6) Decreased red blood cell ALADALAD activity is a very sensitive indicator of lead exposure. Sometimes blood lead is within the normal range, and ALAD activity has been significantly reduced, so it cannot be used as a diagnostic indicator.

Blood test for chronic lead poisoning

(1) Hemoglobin, red blood cell count Chronic lead and severe anemia are mostly mild, which is low pigment anemia, and acute lead poisoning may have hemolytic anemia.

(II) Reticulocytes and basic stippled red blood cells, two types of red blood cells, can increase significantly during lead poisoning and anemia, but they are not unique to severe lead. They are also found in other types of anemia. The detection rate of such cells during the general health screening of workers is not High, but has a reference value for the diagnosis of severe lead poisoning, the upper limit of normal value, 300 red blood cells per million red blood cells, or 10-15 per 50 visual fields.

Third, the main basis for diagnosis and differential diagnosis of lead poisoning are:

(1) History of lead exposure Occupational lead poisoning should have a history of exposure to excessive lead. Learn more about the type of work, working age, and lead concentration in the environment.

Diagnostic check

And protection, the history of exposure to lead poisoning is sometimes obscure. If there are typical multi-system symptoms in clinical practice, the possibility of lead poisoning can often be prompted. You should further ask whether there is a possibility of food or drink contaminating lead, such as Drinking with tin jugs or taking lead-containing drugs recently.

(II) Clinical manifestations of lead poisoning The human body's effect on lead has a certain relationship with the dose of lead. Acute lead poisoning has a rapid onset, and abdominal colic, liver disease, hemolytic anemia, peripheral neuropathy, toxic encephalopathy, and chronic lead severe Can be divided into three levels of light, medium and severe.

(3) Evidence from laboratory examinations of lead absorption. Increased blood lead and urine lead indicate excessive lead absorption in the body. Urinary ALA, urinary fecal porphyrin, and red blood cell ZPP increase, reflecting biochemical reactions caused by pre-absorption. Severe lead, but urinary lead does not exceed the upper limit of normal value, lead flooding test can be performed to assist diagnosis. The method is intravenously or intravenously infused with 1.0 g of sodium edetate disodium, or 0.5 g intramuscularly. Normal Urine lead does not exceed 1.45 mol / L within 24 hours after drug administration. Urine lead often exceeds 3.86 mol / L or 4.82 mol / d during lead poisoning.

With the clinical manifestations of lead poisoning, combined with a history of exposure, and a comprehensive analysis of laboratory positive findings, a diagnosis of lead poisoning can be diagnosed. People with a history of lead exposure, increased blood lead or urine lead, but those without lead poisoning symptoms are diagnosed with lead absorption. The diagnosis of chronic lead severity should be performed in accordance with the "Basic Principles of Occupational Chronic Lead Severity Diagnosis Standard" (GB11504-89) approved by the Ministry of Health.

Differential diagnosis of chronic lead poisoning

(1) Lead toxic abdominal cramps need to be distinguished from other acute abdominal cramps. Lead cramps occur frequently and last for a long time. The lower abdomen is the main part, but it is not fixed and there is no bloating. The abdominal muscles can relax during pain relief. Peripheral red blood cells increase in peripheral blood, and there may be other severe symptoms of lead. Abdominal pain in acute intermittent hematoporphyria is similar to lead colic. The point of identification is that the amount of porphyrin in the urine increases during the onset of the former, and the duration is Longer and no evidence of significant lead absorption.

(2) Lead toxic anemia: Acute anemia should be distinguished from other hemolytic anemias, and chronic anemia should be distinguished from other iron granulocyte anemias and erythrocyte pyrimidine 5 'nucleotidease defects. Mainly rely on a history of lead exposure, evidence of lead absorption, and other symptoms of lead poisoning.

Treatment of chronic lead poisoning

Precautions before treatment of chronic lead poisoning

1. Develop good work and hygiene habits, strictly abide by safe operating procedures, and consider gasoline as a toxic substance in terms of ideology.

2. When working with gasoline, work clothes, rubber gloves and masks should be worn to avoid direct contact between the skin and gasoline. At the same time, you should work at the upwind to prevent gasoline vapor from directly inhaling into the respiratory tract.

3. Do not drink water, do not smoke, or wear clothes wet with gasoline for a long time during work or without washing your hands. After work, wash hands and face with hot water and soap; wash work clothes, masks, and gloves regularly.

4. When pumping gasoline, use a pumping tool. It is strictly forbidden to suck with your mouth to prevent gasoline vapor or gasoline liquid from being sucked into the lungs and stomach.

5. When using gasoline, engine parts and fuel systems are toxic. During maintenance, oil-supplying parts should be immersed in kerosene for a period of time; when the carbon deposits in the combustion chamber are cleared, the carbon deposits should be wetted with kerosene to prevent the scraped powder from flying into the respiratory tract. Do not use your mouth to suck gasoline, petrol pump inlet and outlet valves, and carburetor orifices.

6. If gasoline splashes into the eyes during operation, the eye mucous membranes will wither or bleed. You must immediately rinse with saline or water.

7. Frequently monitor the content of gasoline vapor in the air of the workplace to enhance ventilation; if the "raw oily smell" is found to be too strong, check the engine fuel supply system for oil leakage and eliminate it.

8. People with central nervous system, respiratory tract, cardiovascular and skin diseases are advised not to touch gasoline. ^[2]

The main treatment of chronic lead poisoning

Chronic lead poisoning is mainly treated with lead flooding. At present, the effect of complexing agents with positive effect on lead flooding: CaNa3DTPA (calcium promoting detoxification)

medical treatement

> CaNa2EDTA (calcium edetate)> ZnNa3DTPA (zinc promotes detoxification)> Na2DMS (sodium diphenylsuccinate), DMSA (diphenylsuccinate)> 811 (chelated carboxyphenol),

The specific methods of chronic lead poisoning are as follows

CaNa2EDTA or CaNa3DTPAl.Og, intravenous drip or intravenous bolus or intramuscular injection (plus 2% procaine 2ml), once a day, three consecutive days of drug withdrawal for four days is a course of treatment, usually three courses of treatment. Na2DMSl.Og, intravenous bolus or intramuscular injection (plus 2% procaine 2ml), once a day, three consecutive days of withdrawal and four days as a course of treatment, usually three courses of treatment. DMSAO.5g, orally, three times a day, three consecutive days of withdrawal and four days as a course of treatment, usually three courses of treatment.

Chronic lead poisoning lead colic treatment

Drive lead therapy to lead colic control. 2, symptomatic treatment, 10% 10% calcium gluconate, static push; atropine 0.5 ~ 1.0mg or 654-2, 10mg, intramuscular injection; abdominal hot compress; acupuncture Zusanli, Zhongli, Neiguan. Sanyinjiao, etc.

Prognosis and prevention of chronic lead poisoning

Chronic lead poisoning living environment

Improve production conditions and reduce lead concentration in the air. Production equipment should be mechanized and automated to minimize exposure to lead dust and lead smoke.

Lead pollution

The places where lead dust and lead smoke are generated should be closed, and ventilation devices should be installed to control the temperature of lead melting to reduce the generation of lead smoke. Wet-type operations can be used in the process with a lot of lead dust to carry out technological innovation and use non-toxic substances to replace lead. For example, the pigment in paint replaces lead white with titanium white, and lead red with iron red. Various technical measures are adopted to reduce the lead concentration in the air, and regular inspections are conducted to make the lead concentration in the workshop air not the highest allowable concentration. 0.03mg / m3 of lead smoke and 0.05mg / m3 of lead dust.

Chronic lead poisoning strengthens protection and supervision

Strengthen workers' personal protection and medical supervision. Lead workers should wear work clothes and filter-type lead-proof masks when they work. They should not enter the canteen, dormitory, wash their hands before work, and do not smoke or eat in the workshop. Workers should be regularly monitored for health.

Attention to chronic lead poisoning diet

Avoid accidental ingestion of excessive amounts of lead compounds to prevent the consumption of lead-contaminated foods and beverages. The dosage of lead-containing drugs should be strictly controlled and not excessive.

Chronic lead poisoning health tips

Children with chronic lead poisoning

1. Cultivate children's good hygiene habits. Reduce hand-to-mouth contact with frequent movements and alter dangerous behaviors that may bring lead from the environment into children.

Protective measures

2. Eat less salted fish and preserved eggs, and pay attention to the safety of drinking water at home. The tap water just opened in the morning has a high lead content, so it is best to let it go.

Chronic lead poisoning pregnant women

1. In areas with severe environmental lead pollution, strengthen health education on preventive protective measures for pregnant women to reduce the harm of lead to the fetus.

2. It is best for women not to put on makeup after pregnancy, and to avoid contact with things containing lead.

3. Adequate calcium supplementation during pregnancy can reduce bone calcium mobilization and bone lead release, and reduce fetal lead exposure. Milk and dairy products have high calcium content, which has the effect of preventing lead absorption and reducing the risk of lead poisoning, but drinking milk does not eliminate lead. Consuming some foods with trace elements and high calcium content will make the human body nutritionally balanced, resistance will increase, lead absorption will decrease, so it has a certain preventive effect on lead poisoning.