Cadmium poisoning

Introduction to cadmium poisoning Cadmium poisoning (cadmium poisoning) is mainly caused by inhalation of cadmium soot or cadmium compound dust. A large inhalation can cause acute pneumonia and pulmonary edema; chronic poisoning causes pulmonary fibrosis and kidney disease. The industries exposed to cadmium are smelting and spraying of cadmium, welding and casting bearing surfaces, cadmium rods of nuclear reactors or cadmium-coated graphite rods as neutron absorbers, cadmium storage batteries and other cadmium compounds, etc., Japan reports "pain" It is a chronic cadmium poisoning caused by long-term feeding of water contaminated with cadmium sulfate. basic knowledge The proportion of illness: more common in cadmium industry workers or residents with polluted water quality, the incidence rate is about 0.0004%-0.0007% Susceptible people: no specific population Mode of infection: non-infectious Complications: myocarditis, hepatitis, bronchial pneumonia, edema

Causes of cadmium poisoning

Environmental factors (30%):

Cadmium poisoning is mainly caused by inhalation of cadmium soot or cadmium compound dust. A large inhalation can cause acute pneumonia and pulmonary edema. Chronic poisoning causes pulmonary fibrosis and kidney disease.

Working factors (30%):

The industries exposed to cadmium are smelting and spraying of cadmium, welding and casting bearing surfaces, cadmium rods of nuclear reactors or cadmium-coated graphite rods as neutron absorbers, cadmium batteries and other cadmium compounds.

Dietary factors (35%):

Japan reported that "pain" is a chronic cadmium poisoning caused by long-term feeding of water contaminated with cadmium sulfate.

Pathogenesis:

Cadmium oxide smoke is slowly absorbed in the respiratory tract, about 11% is retained in the lung tissue, cadmium compound is absorbed in the gastrointestinal tract by 5% to 7%, and the rest is excreted by the feces. The absorbed cadmium is mainly excreted by the kidneys, and the milk is also discharged. Through the placenta, affecting the fetus, the cadmium absorbed in the body, the discharge is very slow, only 50% in 10 years.

When cadmium enters the blood, it rapidly combines with metallothionein (MT) to form cadmium metal prion protein (MTCd), about 70% in red blood cells, and 30% in plasma. According to the blood gel chromatogram analysis, there are three cadmium-containing peaks. MT-Cd accounted for about 65%, high molecular protein bound cadmium (HMWP-Cd) accounted for 30%, non-protein small molecule cadmium conjugate (LMW-Cd) accounted for 5%; cadmium in red blood cells except the above three In addition, hemoglobin-bound cadmium (Hb-Cd) accounts for about 5%, of which HMWP-Cd has a major toxic effect. Cadmium in systemic tissues mainly passes through the blood circulation, and cadmium is released into the tissue from the plasma, mainly in the liver. In the kidney, the cadmium content in the liver decreases with time, while the cadmium content in the kidney increases gradually, accounting for about 1/3 of the total cadmium in the body. The toxic effect of cadmium on the tissue is through competition between cadmium and calcium and calmodulin (CaM). Combines, interferes with CaM and its regulated physiological and biochemical systems, inhibits Ca2+-ATPase and phosphodiesterase activity, depolymerizes microtubules in cytoplasm and affects cytoskeleton, stimulates arterial vascular smooth muscle cells to cause elevated blood pressure, cadmium Also stimulates catechol Synthetase activity increased levels of dopamine, inhibition of Na + -K + -ATP enzyme, zinc-containing enzymes, amino acid decarboxylase, histidine, amylase, oxidase activity too.

In particular, leucyl aminopeptidase is inhibited, and the protein is decomposed. The kidney is the main excretion organ of cadmium, and the cadmium is further retained. When the urinary cadmium is 2 g/g creatinine, the urinary 6-keto-prostaglandin 1a (6-ketone) -PGF1a) and sialic acid levels have begun to increase significantly; 4 g / g creatinine, renal tubular antigen BBA, N-acetyl--glucosaminidase (NAG), intestinal alkaline phosphatase (IAP), albumin and Ferritin is elevated in urine; when it reaches 10 g/g creatinine, serum 2 microglobulin (2MG) and urinary 2MG, TH-glycoprotein (THG) and glycosaminoglycan (GAG) are elevated. The above indicators reflect cadmium-induced renal biochemical changes, glomerular barrier function damage, tubular cell damage and dysfunction, cadmium also causes liver cell damage, causing abnormal liver function; hindering intestinal absorption of iron, Induced hypopigmentation anemia, cadmium inhibits 1-antitrypsin (1trypsin) caused by cadmium-induced emphysema (cd-induced emphysema), cadmium has primary damage to blood vessels, causing tissue hypoxia and damage.

Cadmium poisoning prevention

In order to prevent cadmium poisoning, smelting, use of cadmium and its compounds should have good ventilation and containment devices. In addition to the necessary air exhausting equipment, the welding and plating process should be worn with a personal gas mask. Do not eat or smoke at the production site. The maximum allowable concentration of cadmium oxide in the production sites in China is 0.1 mg/m3.

Cadmium-plated utensils cannot store food, especially acidic foods such as vinegar.

Cadmium contaminated soil can cause public nuisance and pain. The pollution of cadmium to the soil mainly depends on two forms. First, the cadmium in the industrial waste gas diffuses around the wind, accumulates in the soil around the factory through natural sedimentation, and the other way is to irrigate the farmland with cadmium industrial wastewater to make the soil Contaminated by cadmium. Therefore, in order to prevent cadmium from polluting the environment, it is necessary to do a good job in environmental protection and strictly enforce the environmental sanitation standards for cadmium.

Cadmium poisoning complications Complications Myocarditis Hepatitis Bronchopneumonia Edema

Long-term consumption of cadmium-contaminated foods may lead to "painful illness", that is, the excessive volume of cadmium damages the renal tubular function, causing the loss of protein in the body from the urine, forming cartilage and spontaneous fractures over time. In addition, chronic cadmium poisoning also has an impact on human fertility, which can seriously damage the Y factor, making the birth of the baby mostly female.

Can cause resorcinal epicarditis, myocardial degeneration, interstitial myocarditis, fibrinous perihepatitis, severe lipid changes in hepatocytes, interstitial hepatitis, fibrosing pneumoconiosis, bronchial pneumonia, balloon effusion, pinching Wall edema and calcification, catarrhal enteritis and cerebral congestion, bleeding and other complications.

Symptoms of cadmium poisoning Common symptoms Weak cough with dyspnea Difficulty breathing Cough with weight loss Dyspepsia chills fever with chills nausea fingers, toenail showing cels... joint pain

Cadmium and its compounds have certain toxicity. Inhalation of cadmium oxide fumes can cause acute poisoning. Early symptoms of soreness, sore throat, cough, chest tightness, shortness of breath, dizziness, nausea, body aches, weakness, fever, etc., severe cases may have toxic pulmonary edema or chemical pneumonia, obvious dyspnea, chest pain, a lot of foamy blood Hey, you can die from acute respiratory failure. Use cadmium-plated utensils to prepare or store acidic foods or beverages. The diet may contain cadmium, which may cause acute cadmium poisoning after eating. The incubation period is short, usually after 10 to 20 minutes, symptoms such as nausea, vomiting, abdominal pain, and diarrhea can occur. Severe cases are accompanied by dizziness, sweating, collapse, upper limbs feeling dull, and even convulsions and shock. It usually takes 3 to 5 days to recover.

Long-term inhalation of cadmium can cause chronic poisoning and cause kidney damage. The main manifestation is that urine contains a lot of low molecular weight protein. Although the filtration function of glomeruli is normal, the recovery function of renal tubules is reduced, and the discharge of urinary cadmium is increased. .

Specific performance

Ingestion acute poisoning

Due to the acidic food in the cadmium-plated container, symptoms appear in a few minutes to several hours, similar to acute gastroenteritis: nausea, vomiting, abdominal pain, diarrhea, malaise, muscle aches, headache, muscle pain, It can be collapsed due to loss of water, and even death due to acute renal failure. The lethal dose of oral cadmium salt in adults is above 300mg.

Inhalation acute poisoning

Inhalation caused by high concentration of cadmium smoke, first symptom of mucous membrane irritation of upper respiratory tract, the above symptoms are relieved after disengagement. After 4-10 hours of incubation, cough, chest tightness, difficulty breathing, chills, back and limb muscles and joint pain, chest X-ray examination with flaky shadows and thickened lung texture. Severe patients with delayed pulmonary edema can die from respiratory and circulatory failure. A small number of liver and kidney damage. Pulmonary fibrosis occurs in a small number of cases after the acute phase, leaving behind pulmonary dysfunction.

Acute cadmium poisoning

According to the history of exposure and respiratory symptoms, diagnosis is not difficult. In addition to occupational history and clinical symptoms, chronic cadmium poisoning is diagnosed in combination with chest radiograph, lung function, renal tubular function, and urinary cadmium.

Acute cadmium poisoning is caused by inhalation, first symptom of mucous membrane irritation of upper respiratory tract, and the above symptoms are relieved after disengagement. After 4 to 10 hours of incubation, cough, chest tightness, difficulty breathing, chills, back and limb muscles and joint pain, chest X-ray examination with flaky shadows and thickened lung texture. Pulmonary edema and heart failure occur in severe patients. The clinical manifestations of poisoning caused by oral cadmium compounds resemble acute gastroenteritis, with nausea, vomiting, abdominal pain, diarrhea, general weakness, muscle soreness, and severe collapse.

Chronic cadmium poisoning

Long-term excessive exposure to cadmium mainly causes kidney damage. In a few serious advanced patients, bone lesions may occur. Inhalation poisoning may cause lung damage.

1, kidney damage: early renal damage manifested as proximal tubular reabsorption dysfunction, low molecular protein in the urine (2 microglobulin, vitamin A binding protein, lysozyme and ribonuclease, etc.), can also appear glucose urine High amino aciduria and high phosphate urine. In addition, high molecular weight proteins (such as albumin, transferrin, etc.) can also be excreted due to glomerular damage. Renal structural damage in advanced patients! Chronic renal failure occurs. Kidney dysfunction will persist even after disengagement. Among workers who have been exposed to cadmium for a long time, the incidence of kidney stones is increased.

2, lung damage: chronic progressive obstructive emphysema, pulmonary fibrosis, and ultimately lead to pulmonary dysfunction. Significant pulmonary dysfunction usually occurs after the appearance of urinary protein.

3, skeletal damage and pain (itai itai disease): severe chronic cadmium poisoning patients with advanced bone damage, manifested as systemic bone pain, with varying degrees of osteoporosis, osteomalacia, spontaneous fractures and severe renal tubules Dysfunction syndrome. Multiple pathological fractures occur in severe patients. Urine tests have low molecular weight proteinuria, increased urinary calcium and urinary phosphate. Blood cadmium is increased and blood calcium is lowered. The occurrence of pain is related to factors such as nutritional factors (low protein, low calcium and low iron) and multiple pregnancy.

4. Others: Chronic poisoning patients are often accompanied by yellowing of the neck of the teeth, loss of olfactory or loss, ulceration and atrophy of the nasal mucosa, mild anemia, occasional loss of appetite, nausea, mild abnormal liver function, weight loss and high blood pressure. Long-term exposure to cadmium, the incidence of lung cancer increased.

Cadmium poisoning check

Cadmium

The normal value of urinary cadmium is mostly below 1 g/g creatinine (or 1 g/L), and the upper limit is more than 5 g/g creatinine (or 5 g/L). Urinary cadmium can reflect the recent cadmium exposure and to some extent reflect the cadmium load in the body, especially the cadmium level in the kidney.

Blood cadmium

Blood cadmium fluctuates greatly and can be used as an indicator of recent exposure. The World Health Organization recommends an individual blood cadmium threshold of 10 g/L. In chronic cadmium poisoning, urinary 2MG often exceeds 420 g/g creatinine (420 g/L), and even exceeds 1000 g/g creatinine (1000 g/L).

other

In addition, there may be an increase in excretion of urinary 6-keto-PGF1, NAG, IAP, THG, and GAG.

Diagnosis and identification of cadmium poisoning

diagnosis

Acute cadmium poisoning: Diagnosis is not difficult based on exposure history and respiratory symptoms.

Chronic cadmium poisoning: In addition to occupational history and clinical symptoms, combined with chest X-ray, lung function, renal tubular function and urinary cadmium to make a diagnosis.

Differential diagnosis

Ingestion acute poisoning should be differentiated from food poisoning and acute gastroenteritis; inhalation acute poisoning should be differentiated from upper respiratory tract infection and cardiogenic pulmonary edema. Chronic cadmium poisoning needs to be differentiated from other heavy metals or drugs that cause renal dysfunction.

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