Mercury poisoning

Hg (mercury, Hg), also known as the mercury is the only liquid at room temperature and flowable metal. The specific gravity is 13.595 and the specific gravity of the vapor is 6.9. Mercury is easily evaporated into the air and causes harm because: 1. It has evaporated at 0 °C. The higher the temperature, the faster the evaporation. The evaporation rate increases by about 1.2 to 1.5 times for every 10 °C increase, and the evaporation increases when the air flows. . 2. Mercury is insoluble in water and can be evaporated into the air through the surface water seal. 3, the viscosity is small and the fluidity is large, it is very fragile into small mercury beads, and it remains in the gaps of the workbench, the ground, etc. without holes. It is difficult to remove, and the surface area is increased and a large amount of evaporation is formed, forming a secondary pollution source. 4. Surfaces, work benches, walls and ceilings all absorb mercury vapor. Sometimes, the mercury workshop is used for other purposes, and there is still a problem of mercury hazard. Workers' clothing and skin contamination can be brought to the home to cause harm.

There are many kinds of metal mercury production, such as the mining of mercury mines and the smelting of mercury, especially the soil-fired mercury smelting, pollution of air, soil and water quality; manufacturing, calibration and maintenance of mercury thermometers, sphygmomanometers, flow meters, Liquid level gauges, control instruments, barometers, mercury rectifiers, etc., especially with hot mercury method, produce more harmful; manufacture fluorescent lamps, ultraviolet lamps, film projection lamps, X-ray tubes, etc.; as a raw material for the production of mercury compounds in the chemical industry Or as a catalyst such as salt cathode for mercury electrolysis to produce chlorine gas, caustic soda, etc.; amalgam method to extract precious metals such as gold and silver and gold plating, gold, etc.; dental department with silver amalgam to fill dental caries; 钚 reactor coolant, and so on. Inorganic compounds such as mercury nitrate, mercury (Hg (NO3) 2), mercuric chloride (HgCl2), calomel (HgCl), mercury bromide (HgBr2), arsenic acid, mercury (HgAsO4), mercury sulfide (HgS), mercury sulfate ( HgSO4), oxidized mercury (HgO), mercury cyanide (Hg(CN)2), etc., used in the synthesis of mercury compounds, or as catalysts, pigments, coatings, etc.; some also as drugs, oral, excessive inhalation of dust and Poisoning can occur when the skin is applied. In addition, thunder mercury (Hg(CNO)2·1/2H2O) is used to manufacture detonators and the like. Absorption, distribution, excretion

Metallic mercury invades the body from the respiratory tract in the form of vapor. The amount of skin absorbed is small, but the amount of absorption is greater when the skin is damaged or ulcerated. The digestive tract is basically not absorbed, so healthy people taking oral metal mercury will not cause poisoning. Intravenous or subcutaneous injection of metallic mercury can cause poisoning, and there have been reports of poisoning by submerged thermometers. Mercury vapor easily enters the body through the alveolar membrane and is dissolved in the blood. Generally, the inhaled mercury vapor can be absorbed by the alveoli about 50%, and the rest is exhaled. When the concentration of mercury in the air increases, the absorption rate also increases. Mercury in the blood is initially distributed in red blood cells and plasma, and later reaches the organs of the body, and the content in the kidney is more than 70% to 80% of the total mercury in the body. Mercury can enter the brain through the blood-brain barrier and accumulate in the brain for a long time, with the largest in the cerebellum and brainstem. It is also easy to enter the fetus through the placenta and accumulate disease. Mercury is discharged from urine, feces, bile, milk, sweat, saliva, etc. The discharge of urinary mercury accounts for about 70% of the total discharge, but the discharge of urinary mercury is irregular, and the difference can be about 4 times per day. More than a decade after the cessation of contact, urinary mercury can still exceed normal. Poisoning Mechanisms Mercury in blood and tissues can bind to sulfhydryl groups in proteins and enzyme systems, inhibiting their function, or even inactivating them, for example, in combination with thiol-containing lipoic acid, pantosyl hydrothylamine and coenzyme A. Metabolism of the brain pyruvate. Mercury acts on reduced glutathione, impairing its redox function. There are more non-functional sulfhydryl groups in the body which constitute the hydrophobic part of globulin. If combined with mercury, the volume is reduced, and the whole molecule is distorted and the enzyme is inactivated. High concentrations of mercury can also bind to amino groups, hydroxyl groups, phosphoryl groups, carboxyl groups, etc. in the enzyme, causing corresponding damage. Mercury can activate phospholipases in cells through calcium ions, decompose phospholipids in cells, and form arachidonic acid and oxygen free radicals to impair its function. Mercury binds to proteins in the body and can be converted into antigens by haptens, causing allergic reactions and nephrotic syndrome. High concentrations of mercury can also directly cause glomerular immune damage. Mercury can inhibit T cells and cause damage to their own immunity. In addition, the lymphocyte micronucleus rate and chromosome aberration rate of mercury contacts increased. Mercury reduces ovarian hormone secretion, which can cause menstrual disorders and abnormal pregnancy.

The toxic effects of mercury are multifaceted, and the specific details of many of the above changes are still being studied in depth. Most cases of acute poisoning are caused by a large inhalation of high concentrations of hot mercury vapor in a short period of time, mainly acute interstitial pneumonia and bronchiolitis. Patients with high inhalation concentration and long time are seriously ill. The patient had fever, chest tightness, shortness of breath, cough, and phlegm, increased white blood cell count in the surrounding blood, and auscultation of rough and wet rales in the lungs. X-ray chest radiographs can see darker, cloud-like blurred shadows in one leaf (mostly in the lower right lung), in the lower part of the lungs, or in most of the lung fields. Lighter can be gradually relieved, and severe can lead to death. In addition, there are kidney damage and stomatitis, and there are changes in urine protein, cast, oliguria, salivation, gingival swelling and pain.

Most cases of chronic poisoning are caused by long-term inhalation of metal mercury vapor. The first symptoms of general debilitation, such as mild dizziness, headache, forgetfulness, and multiple dreams, may be caused by palpitations, excessive sweating, and other autonomic nervous system disorders. When the disease progresses to a certain extent, there are three typical manifestations: irritability, intentional tremor, and stomatitis. Excitability: the psychiatric symptoms of chronic mercury poisoning, such as insomnia or lethargy, many nightmares, temperament depression, solitude and irritability, easy to be excited and angry, and unable to control themselves, losing interest in past hobbies Suspicious, can not be grouped and like to live alone, but timid, afraid to see people, sober, funny, and so on. In short, both personality and mood have changed significantly.

Intentional tremor: The fingers, the tip of the tongue, and the eyelids are obviously tremors, and the tremors of the fingers and hands are most prominent. In the early stage, it was a small tremor. When the condition worsened, it showed a large jittery tremor. In severe cases, the wrist, forearm, and even the two legs and calves also had tremors. The characteristic is intentionality, that is, when the tremor starts at the action, it is aggravated during the action, and the tremor stops after the action is completed. For example, drinking water, when the water is rubbed with a spoon, the fingers and hands begin to tremble. During the process of retrieving the spoon into the mouth, the tremor is aggravated and the water is poured out from the spoon. After the spoon is sent to the mouth, the tremor stops. Similar characteristics can be seen in the finger test and the finger test. When the patient writes, the strokes are not neat and complicated due to tremors. When writing large characters, drawing large circles, being noticed by others or being nervous, the degree of tremor is often more pronounced. After one or two months of hospitalized mercury-suppressing treatment, it can be seen that the tremor has been alleviated, but the seriously ill person is only temporarily relieved. In addition, the seriously ill person is not flexible in speech. When the eager speech is spoken, the tongue does not listen and is stuttering, and the voice is unclear. The patient's gait is also unstable, and it is more obvious when going down the stairs. In general, patients do not have resting tremors, but patients with severe poisoning may experience resting tremors when excited.

Stomatitis: mainly seen in patients with more severe conditions, the early complaints are the increase of metal taste and saliva in the mouth, and the pillowcase is wet when waking up in the morning. Gingival and buccal mucosa examination showed a copper color was red, swollen gums, easy bleeding, gingival line of mercury, swelling of the tongue and the "teeth marks." The disease is severe and the disease is long and the teeth are loose and easy to fall off. Kidney damage: Mercury mainly damages the renal proximal convoluted tubules, but does not necessarily have symptoms. Urine test, in addition to increased urinary mercury, can be seen in urine protein, cast, N-acetyl-β-D-glucosidase (NAG), urinary γ-glutamyltranspeptidase (γGT), β2 microglobulin increase, etc. Variety. Others: Mercury is a systemic toxicant. In addition to the above-mentioned central nervous system, kidney and oral lesions, changes observed in animal experiments or in contact with humans have reproductive dysfunction (menstrual disorders, infertility, abnormal fertility, ** dying , sperm variability, etc.), mercury toxic dermatitis, mercury toxicity and immune dysfunction. Diagnosis of acute mercury poisoning: a large amount of inhalation of high concentrations of mercury vapor or mercury inorganic compound dust in a short period of time, together with inhalation, X-ray chest radiographs see deeper dark shadows in some or most of the lung fields, and kidneys Damage and stomatitis. Need to be differentiated from pneumonia and kidney damage caused by other causes. The characteristic of this disease is that the urinary mercury can be increased by as much as 5mg/L, and the timely mercury-discharging therapy can release a large amount of mercury and promote the condition to gradually improve.

Chronic mercury poisoning: The main diagnosis is based on long-term exposure to mercury, the above clinical manifestations and increased urinary mercury. It is not difficult to diagnose a typical patient, but it is rare to see such cases. Patients with early mild poisoning are often encountered in the clinic. Sometimes it is necessary to observe the diagnosis for a period of time. The main objective basis in clinical diagnosis is different degrees of "three tremors", but healthy people also have mild eyelid tremors, and tongue tremors must appear when the condition is heavy, which is difficult to rely on. Generally, finger tremor is an indispensable basis. It should be noted that some healthy people, especially the elderly, often have finger tremors, but the tremor is small, the tendency of unintentional tremor, and not because of the attention of others. Tight and aggravated. Obvious writing, drinking tremor, finger-nose test, and positive finger test only occur when the condition is severe. Therefore, in practice, the diagnosis is often determined by clear symptoms of debilitating disease and mercury content in biological monitoring. Urine is commonly used. HG. However, the excretion of urinary mercury is very irregular. The amount of urinary mercury in the same person for 24 hours in 4 to 7 days can vary by many times, so the average value is often used. It is not necessarily parallel to the symptoms. At the same air concentration, the urinary mercury of each contact is often significantly different. The upper limit of the normal value, the different test methods and the results of each region are quite different. It is generally considered that the double sulfur brown method is 0.25 μmol/(0.O5 mg/L), and the flame atomic absorption method is 0.1 μmol/L (O.O2 mg/L). In addition, the upper limit of the normal value of blood mercury is 0.5 μmol/L (0.01). Mg/L), the upper limit of normal saliva mercury is 0.25μmol/L (0.05mg/L), and the upper limit of normal mercury is 4mg/100g, which can be used for reference. Mercury poisoning were erythrocyte aminolevulinic acid dehydratase (of ALAD) also decreased, but obviously far no lead poisoning, is generally not as a diagnosis. Diagnostic grading is usually divided into four levels: 1. Mercury absorption, no clear signs and symptoms, but urinary mercury or urine flooding increases, about 2 to 4 times higher than normal. 2, mild chronic mercury poisoning, mild symptoms of debilitating, finger tremor or renal function changes, stomatitis, etc., urinary mercury or urine flooding increased. 3, moderate chronic mercury poisoning, there are obvious emotional disorders or personality abnormalities, finger tremor or renal function changes, stomatitis, etc., urinary mercury and urine flooding increased. 4, severe chronic mercury poisoning, obvious mental symptoms, prominent acral tremor, toxic encephalopathy or toxic nephropathy, urinary mercury and urine flooding significantly increased. In the prevention of production, try to replace mercury with other non-toxic or low-toxic substances, such as replacing mercury in the meter with ethanol, petroleum , toluene, etc., replacing the mercury thermometer with a thermal resistance thermometer, and replacing the mercury electrode with a diaphragm electrode for salt electrolysis. Evaporation of mercury increases with increasing temperature. Process reforms are required, such as the replacement of the hot mercury method with cold mercury. The production of mercury should be as close as possible to contain airtightness and automation, and supplemented with adequate suction or side suction extraction equipment. The discharged mercury-containing gas is purified and disposed of in the atmosphere.

The mercury level of the open container can be covered with glycerin or 5% sodium sulfide solution to prevent evaporation of the mercury vapor. In workshops with metal mercury, worktables, floors and walls should be made of materials that are smooth and do not absorb mercury, and coated with perchloroethylene coating to prevent mercury penetration and adsorption; and implement strict sanitation systems, such as Rinse regularly. The cleaning solution should be discharged after removal of mercury. When the concentration of mercury vapor in the workshop is high, the iodine can be fumigated after closing the doors and windows, so that the mercury vapor and the iodine vapor form the non-volatile mercury iodide, which is settled and then removed with water. Formulate safe operation methods and strengthen individual protection. If you do not eat or smoke in the workshop, work clothes will not be taken out of the workshop, and both hands will be cleaned after work. Nervous system, kidney, oral disease, female workers during pregnancy and lactation are employment contraindications. Young women who are married at the end of the marriage are not exposed to mercury. Patients with moderate and severe chronic mercury poisoning should be permanently separated from mercury.

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