Chronic lead poisoning

Introduction to chronic lead poisoning Chronic lead poisoning is a non-infectious chronic disease caused by the cumulative absorption of lead. Typical symptomatic children with lead poisoning are not common. Most children have no signs of brain lesions but have persistent behavior and cognition. Problems that seriously affect health and learning. When it is characterized by irritability, loss of appetite, personality change, abdominal cramps, etc., its blood lead content is generally around 50g/dL, which is already a serious lead poisoning. basic knowledge The proportion of sickness: 0.012 Susceptible people: no special people Mode of infection: non-infectious Complications: epilepsy

Causes of chronic lead poisoning

Environmental factors (75%)

The lead and its compounds contained in the environment are highly toxic to the human body, invade the body through the respiratory tract, and can accumulate in the human body. And cause chronic lead poisoning. Such as batteries, X-rays, etc.

Pathogenesis

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 high solubility are easily absorbed into the body, which is highly toxic, and lead is easily combined with sulfhydryl groups of proteins in the body. It can inhibit thiol-containing enzymes, especially several enzymes related to heme synthesis. Lead inhibits erythrocyte delta--amino-r-ketovalerate dehydratase (ALAD), which increases serum and urinary -amino-r-ketovaleric acid (ALA), and lead inhibits coproporphyrinogen decarboxylase, causing urine in the feces. Increased porphyrin, lead inhibits heme synthase, interferes with iron and protoporphyrin to form heme, and affects hemoglobin production, resulting in accumulation of iron (forming ring-shaped iron granules) and free protoporphyrin (FEP) in young red blood cells The free protoporphyrin is chelated with zinc to form zinc protoporphyrin (ZPP).

Lead poisoning can increase the number of rainbow cells, which is because lead inhibits erythrocyte pyrimidine-5-nucleotide plum, which causes the degradation of pyrimidine nucleotides in erythrocytes, and also hinders the degradation of ribosomal RNA. Degraded pyrimidine nucleotides and ribosomal RNA form basophilic spots.

Lead is attached to the erythrocyte membrane, interfering with Na+, K+ATPase, and making red blood cells fragile and easy to hemolyze.

In recent years, ALA has been found to pass the blood-brain barrier. A large amount of ALA entering the brain tissue during lead poisoning can cause various behavioral and neurological effects. The mechanism may be that ALA is similar in structure to r-aminobutyric acid (GABA) and can compete with GABA for postsynaptic membrane. The GABA receptor affects the function of GABA.

Chronic lead poisoning prevention

1, should develop good work and health habits, strictly abide by the safe operating procedures, in the ideological understanding of gasoline should be regarded as a toxic substance.

2, work must be in contact with gasoline, should wear overalls, wear rubber gloves and masks, try to avoid direct contact between body skin and gasoline; at the same time should stand on the upper air outlet to prevent gasoline vapor directly into the respiratory tract.

3. When working or when the hands are not cleaned, do not drink water, do not smoke, do not wear clothes that are invaded by gasoline for a long time, apply hot water and soap after work, wash your face, work clothes, masks, gloves should Wash and change frequently.

4. Use oil pumping tools when adding gasoline. It is strictly forbidden to suck directly with your mouth to prevent gasoline vapor or gasoline liquid from inhaling into the lungs and stomach.

5. When using gasoline, the engine parts and fuel system are all toxic. During maintenance, the oil supply parts should be placed in the kerosene for a period of time; when removing the carbon deposit in the combustion chamber, the kerosene should be used first. The carbon is wetted to prevent the scraped powder from being sucked into the respiratory tract. Do not use the mouth to suck the gasoline, the gasoline pump, the oil discharge valve and the carburetor.

6. If gasoline is splashed into the eye during operation, it will cause the eye mucosa to wither or bleed. It must be rinsed immediately with saline or water.

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

8, people with central nervous system, respiratory, cardiovascular and skin diseases, it is best not to contact gasoline.

Chronic lead poisoning complications Complications

Early termination of lead poisoning has a good prognosis. Although the cerebral symptoms are often found after treatment, sequelae such as epilepsy and mental dysplasia are often caused by diseases such as epilepsy and infections that are lurking in the bones and often invade the blood circulation and cause recurrence until heavy on the X-ray. The lead band disappeared without any trouble.

Chronic lead poisoning symptoms Common symptoms Loss of appetite Mental disorder Debilitating coma Sleepiness Meningitis Intestinal refractory constipation convulsions Dizziness

Occupational lead poisoning is mostly chronic poisoning, and there are clinical symptoms of nervous, digestive, and blood systems.

1, the nervous system: mainly manifested as neurasthenia, multiple neuropathy and encephalopathy.

Shenshen is one of the early and more common symptoms of lead poisoning. It is characterized by dizziness, headache, general weakness, memory loss, sleep disturbance, and multiple dreams. Among them, dizziness and general weakness are most obvious, but they are generally lighter. Is a functional symptom.

Multiple neuropathy can be divided into sensory, sports and mixed type. The sensory type is characterized by numbness of the extremities and glove-sock-type sensory disturbance at the extremities.

Encephalopathy, the most serious lead poisoning, manifests as headache, nausea, vomiting, high fever, irritability, convulsions, lethargy, mental disorders, coma and other symptoms, similar to seizures, meningitis, cerebral edema, psychosis or local brain damage.

2, digestive system: light manifestations of general gastrointestinal symptoms, severe abdominal cramps.

Symptoms of the digestive tract include metallic taste in the mouth, loss of appetite, swelling of the upper abdomen, discomfort, abdominal pain and constipation. The dry stool is a beaded shape. Before the onset of lead colic, there are often intractable constipation as a precursor, and abdominal cramps are sudden attacks. More in the umbilical cord, persistent pain and paroxysmal aggravation, each episode from a few minutes to a few, when examined, the abdomen is flat and soft, may have mild tenderness, no fixed tenderness points, reduced bowel sounds, often accompanied There is a temporary increase in blood pressure and a fundus of the fundus.

3, the blood system: mainly lead interference in the hemoglobin synthesis process caused by changes in its metabolites, and finally lead to anemia, mostly low pigmented normal red blood cell type anemia.

Chronic lead poisoning test

Determination of lead in human body

(1) Blood lead is a recent pre-absorption index, and the upper limit of normal blood lead is 2.4 mol/L (50 g/dl).

(2) Lead in urine can reflect the absorption of lead, and the upper limit of normal urine lead is 0.39 mol/L (0.08 mg/L).

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

(D) urinary fecal porphyrin (urinary brown pigment) increased fecal porphyrin in urine also seen in hematoporphyria, liver disease and alcoholism and barbiturate poisoning, urinary fecal porphyrin semi-quantitative ++ is positive.

(5) Erythrocyte free protoporphyrin (FEP) and erythrocyte zinc protoporphyrin (ZPP) are sensitive indicators reflecting lead absorption. ZPP is measured by blood fluorometer, which is quick to operate and convenient for on-site inspection. The upper limit of FEP is normal. 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) Red blood cell ALADALAD activity reduction is a very sensitive indicator reflecting lead exposure. Sometimes blood lead is within the normal range, ALAD activity has been significantly reduced, and therefore can not be used as a diagnostic indicator.

blood test

(1) Hemoglobin, red blood cell count Chronic lead severe anemia is mild, low pigmented anemia, acute lead poisoning may have hemolytic anemia.

(2) Reticulocytes and alkaline red blood cells can significantly increase in lead poisoning anemia, but they are not unique to lead severity, but also in other types of anemia. The detection rate of such cells in workers' health screening is not High, but for the diagnosis of severe lead poisoning, there is a reference value of the upper limit of normal value, 300 red blood cells / million red cells, or 10-15 / 50 fields of view.

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

(1) History of lead exposure Occupational lead poisoning should have a professional history of exposure to excessive lead. Learn more about the type of lead work, the age of work, and the concentration of lead in the environment for diagnostic examination and protection. The history of exposure to lead poisoning is sometimes hidden. Clinically, there are typical multi-system symptoms that often indicate the possibility of lead poisoning. Further question should be asked about the possibility of contamination of lead with food or beverages, such as drinking from tin wine bottles or taking lead-containing drugs in the near future.

(B) the clinical manifestations of lead poisoning The effect of human lead on lead has a certain relationship with the lead dose, acute lead poisoning onset, acute abdominal cramps, liver disease, hemolytic anemia, peripheral neuropathy, toxic encephalopathy, chronic lead severity Can be divided into light, medium and heavy three levels.

(III) Laboratory test evidence of lead absorption The increase of blood lead and urinary lead indicates that the body has absorbed excessive lead, and urine ALA, urinary porphyrin and erythrocyte ZPP increase, reflecting the biochemical reaction caused by absorption before, such as according to occupation history and doubt. There is heavy lead, but the lead in urine does not exceed the upper limit of normal value. The lead-discharge test can be used to assist the diagnosis. The method is to use intravenous injection or intravenous drip of 1.0 g of disodium edetate or 0.5 g of intramuscular injection. The urine lead does not exceed 1.45 mol/L within 24 hours after administration, and the lead in the lead poisoning often exceeds 3.86 mol/L or 4.82 mol/d.

With clinical manifestations of lead poisoning, combined with exposure history, and laboratory positive findings for comprehensive analysis, can diagnose lead poisoning, lead exposure history, blood lead or increased urine lead, but lead-free poisoning symptoms are diagnosed as lead absorption, The diagnosis of chronic lead severity should be carried out in accordance with the Principles for the Diagnosis of Occupational Chronic Lead Severity Standards (GB11504-89) approved by the Ministry of Health.

Diagnosis and identification of chronic lead poisoning

diagnosis

It can be diagnosed according to clinical symptoms and various examinations.

Differential diagnosis

(1) lead toxic abdominal cramps, need to be identified with other acute abdomen, lead colic attacks frequently, long duration, the site below the main abdomen, but not fixed, no abdominal distension, abdominal muscles can relax during pain relief, Peripheral blood in the increase of erythrocytes, and may have other symptoms associated with lead severity, acute intermittent hematoporphyria abdominal pain is similar to lead colic, the point of identification is that the former urinary bilirubin increased significantly, the duration Longer and no evidence of lead absorption.

(2) lead toxic anemia: acute anemia should be differentiated from other hemolytic anemia, chronic anemia should be differentiated from other iron granulocyte anemia, erythrocyte pyrimidine 5 'nucleotidase deficiency. Mainly rely on lead exposure history, evidence of lead absorption and other symptoms of lead poisoning.

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