1. Metal and metalloid poisons

(1) Lead

Silver-gray soft metal, strong malleability, relative density of 11.35, melting point of 327 ° C, boiling point of 1620 ° C. When heated to 400-500 ° C, a large amount of lead vapor escapes, rapidly oxidizes into lead oxide and lead oxide in the air, and condenses into soot. Insoluble in dilute hydrochloric acid and sulfuric acid, soluble in nitric acid, organic acids and lye.

Lead is a systemic toxicant that primarily affects porphyrin metabolism. Porphyrin is the main component of synthetic hemoglobin, thus affecting the synthesis of heme and producing anemia. Lead can cause vasospasm, retinal arteriolar spasm, and high blood pressure. Lead can also act on organs such as the brain and liver, causing toxic lesions.

(2) Mercury

It is a silvery white liquid at room temperature, density 13.6, melting point -38.87 ° C, boiling point 356.9 ° C. It has low viscosity, easy flow and dispersion, strong adhesion, and can absorb mercury from floors and walls. It evaporates at room temperature, the temperature rises, and evaporation accelerates. Insoluble in water, soluble in lipidoids, soluble in nitric acid, hot concentrated sulfuric acid. It can dissolve a variety of metals and produce amalgam.

Mercury ions have a strong affinity with sulfhydryl groups and dihydrazino groups in the body. Mercury binds to the active thiol group of certain enzymes in the body, causing the enzyme to become inactive, causing cell damage and leading to poisoning.

(3) Chrome

Steel gray, hard and brittle metal, relative density 7.20, melting point 1900 ° C, boiling point 2480 ° C. Slow oxidation and corrosion resistance. Do not dissolve in water, soluble in hydrochloric acid, hot sulfuric acid. Hexavalent chromium is the most toxic in chromium compounds. The main raw material of the fertilizer industry catalyst, chromium trioxide, is a strong oxidant, soluble in water, and often exists in the air of the plant in an aerosol state.

Hexavalent chromium compounds are highly irritating and corrosive. Chromium can affect the process of oxidation, reduction and hydrolysis in the body, which can denature proteins, cause precipitation of nucleic acids and nuclear proteins, and interfere with the enzyme system. Hexavalent chromium inhibits the activity of urease, and trivalent chromium has an inhibitory effect on thromboplastin.

(4) Manganese

Light gray hard and brittle metal. The temperature of 1260 ° C, the boiling point of 2097 ° C, soluble in dilute acid.

The toxicity of manganese and its compounds varies, and the lower the valence of manganese in the compound, the greater the toxicity. Chronic poisoning is the main cause of industrial production, mostly caused by inhalation of high concentrations of manganese and manganese dust. Mild poisoning manifested as insomnia, headache, memory loss, numbness of the limbs, and slow behavior. Severe poisoning patients have symptoms such as stiff limbs, slow and clumsy movements, unclear language, and decreased intelligence.

2, organic solvent

(1) benzene

A colorless, volatile, flammable liquid with an aromatic odor. The density is 0.879, the melting point is 5.5 ° C, and the boiling point is 80.1 ° C. Do not dissolve in water, soluble in organic solvents such as ethanol and ether.

The mechanism of benzene poisoning is still unclear. It is generally believed that benzene poisoning is caused by phenol, a metabolite of benzene. Phenol is a protoplast poison that directly inhibits the nuclear division of hematopoietic cells, and has a more toxic effect on the early active cells with the most active nuclear division in the bone marrow, which damages the hematopoietic system. In addition, benzene has a hapten-like property, and can bind to a protein molecule through a covalent bond, denatures the protein, has antigenicity, and undergoes an allergic reaction.

(2) toluene

It is a colorless, aromatic liquid. The boiling point is 100.6 ° C. Do not dissolve in water, soluble in organic solvents such as ethanol and ether.

Toluene is less toxic and is low in toxicity. In industrial production, toluene enters the human body mainly through the respiratory tract in a vapor state, and the skin absorbs little. Acute poisoning is characterized by anesthesia of the central nervous system and symptoms of autonomic dysfunction. Chronic poisoning is mainly caused by long-term inhalation of higher concentrations of toluene vapor, dizziness, headache, weakness, insomnia, memory loss and other phenomena.

(3) Carbon tetrachloride

It is a colorless, transparent, volatile oily liquid. The temperature of -22.9 ° C, the boiling point of 76.7 ° C. Non-flammable, fire or hot surfaces can be decomposed into carbon dioxide, hydrogen chloride, phosgene and chlorine. Slightly soluble in water, soluble in organic solvents.

Carbon tetrachloride vapor enters the human body mainly through the respiratory tract, and both liquid and vapor can be absorbed through the skin, causing acute and chronic poisoning.

3. Nitrobenzene and aniline

Nitrobenzene is a five-color or light yellow oily liquid with a bitter almond odor. The relative density is 1.2037, the melting point is 5.7 ° C, and the boiling point is 210.9 ° C. Almost insoluble in water, soluble in ethanol, ether or benzene.

Aniline is a colorless oily liquid with a special odor. The relative density is 1.022, the melting point is -6.2 ° C, and the boiling point is 184.4 ° C. Slightly soluble in water, soluble in alcohol, ether and benzene.

After the nitro group and amino compound of benzene enter the human body, they are converted into nitrophenol and aminophenol by oxidation, so that hemoglobin becomes methemoglobin. Methemoglobin loses oxygen carrying capacity and causes tissue hypoxia. These poisons can also cause rupture of red blood cells, hemolytic anemia, and direct damage to organs such as the liver, kidneys, and bladder.

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