Personal hazards during degreasing

Compare it yourself! ----------------------- Trichloroethylene CHCI=CCl2 is a colorless liquid with a chloroform-like odor. (1) Contact opportunities: In industry, it is mainly used as a degreasing agent for metals and an extractant for fats, oils, paraffins, etc. It is also used in the organic synthesis industry. Used in medicine in the past * * agent. (2) Toxicity and main clinical manifestations: Trichlorethylene is an accumulation * * agent, can be absorbed through the respiratory tract, digestive tract and skin. It has a strong inhibitory effect on the central nervous system and has certain side effects. That * * The effect is slightly less than that of chloroform. Severe cases of acute poisoning may include headache, dizziness, tinnitus, inebriation, unsteady gait, fatigue, irritability, hysterical symptoms, drowsiness or insomnia, numbness of the limbs, tremors, muscle and joint pain, etc. Severe cases include delirium, convulsions, confusion, coma, respiratory paralysis or circulatory failure. It can cause toxic hepatitis and trigeminal nerve paralysis, resulting in smell and taste disorders, and loss of sensation in the face and front of the tongue. Chronic poisoning presents with fatigue, reduced work ability, headache, episodic dizziness, sleep disorders, gastrointestinal disorders, palpitations, chest pressure, arrhythmia, peripheral neuritis, autonomic nerve dysfunction and liver damage. The characteristics of trigeminal nerve palsy are the same as those seen after acute poisoning. Skin contact can cause dermatitis, eczema, dry skin and secondary infection. (3) Reproductive and developmental toxicity: Петров-Маслаков report (1973), female workers exposed to trichlorethylene had higher incidence rates of threatened abortion, spontaneous abortion and premature birth than the control group. The incidence of pregnancy-induced hypertension was also higher than that of the control group, but the incidence of pregnancy obstruction was lower than that of the control group. The author believes that this may be related to the effect of trichlorethylene on the nervous system. * * Function related. The incidence of labor weakness and postpartum uterine involution was higher than that in the control group. In animal experiments, rats and mice were exposed to 300ppm trichlorethylene for 7 hours daily on days 6 to 15 of pregnancy. No teratogenic effects were found, and no toxic reactions were found in either mother rats or fetal rats. When male mice were exposed to trichlorethylene at concentrations of 50, 202 and 450 ppm for 24 hours and then mated with female mice, no obvious lethal effect occurred and their fertility was not affected. Trichlorethylene is one of the most commonly used solvents in production, so attention should be paid to its reproductive toxicity and developmental toxicity. --------------------- [Physical and Chemical Properties] Carbon tetrachloride (CCl4), also known as tetrachloromethane, is a colorless, volatile, non-flammable liquid. Slightly sweet smell of chloroform. The molecular weight is 153.84, the density is 1.595g/cm3 (20/4℃), the boiling point is 76.8℃, the vapor pressure is 15.26kPa (25℃), and the vapor density is 5.3g/L. Slightly soluble in water, miscible with ethanol, ether, chloroform and petroleum ether. It can decompose into carbon dioxide, hydrogen chloride, phosgene and chlorine when exposed to fire or hot objects. [Occupational exposure] Carbon tetrachloride is widely used and has been used as insect repellent and dry cleaning agent in the past. At present, it is mainly used as a chemical raw material for the manufacture of chlorofluoromethane, chloroform and a variety of drugs; as an organic solvent, it has good performance and is used as a solvent for oil, fat, wax, rubber, paint, asphalt and resin; it is also used as a fire extinguishing agent, fumigant, and cleaning agent for machine parts and electronic parts. During its manufacturing and use, there may be contact with carbon tetrachloride. [Toxicity] This product is a typical liver poison, but the concentration and frequency of exposure can affect its site of action and toxicity. At high concentrations, the central nervous system is first affected, and then the liver and kidneys are affected; while long-term exposure at low concentrations mainly affects the liver and kidneys. Ethanol can promote the absorption of carbon tetrachloride and aggravate poisoning symptoms. In addition, carbon tetrachloride can increase the sensitivity of myocardium to epinephrine and cause serious arrhythmias. People's individual susceptibility to carbon tetrachloride varies greatly. It has been reported that oral administration of 3 to 5 ml can cause poisoning, and 29.5 ml can cause death. Poisoning may occur at a concentration of 160~2OOmg/m3. However, mild poisoning may occur after exposure for 30 minutes at a concentration of 1 to 2 g/m3. It is currently believed that carbon tetrachloride has no teratogenic or mutagenic effects, but it is embryotoxic. According to IARC1972 and 1979 data, carbon tetrachloride can cause liver cancer in rodents under long-term effects, and is classified as a chemical with "possible carcinogenicity to humans." [Clinical manifestations] 1. Acute poisoning (1) Incubation period: generally 1 to 3 days, sometimes as short as a few minutes. The length of the incubation period is related to the exposure dose and route of entry. The clinical manifestations of poisoning absorbed through the respiratory tract or gastrointestinal tract are similar; the central nervous system may occur in both cases * * and symptoms of liver and kidney damage. (2) Nervous system symptoms: dizziness, headache, fatigue, confusion, gait staggering, temporary disturbance of consciousness or coma, etc. When extremely high concentrations are inhaled, coma, convulsions, and even sudden death can occur quickly due to suppression of the medulla oblongata. (3) Gastrointestinal symptoms: more obvious when taken orally. There may be signs of toxic liver disease such as nausea, vomiting, loss of appetite, abdominal pain, diarrhea and jaundice, hepatomegaly, tenderness in the liver area, and abnormal liver function. In severe cases, fulminant liver failure may occur. Symptoms of liver damage usually appear on the 2nd to 4th day after onset. (4) Symptoms of kidney damage: proteinuria, red blood cell urine, and cast urine may occur. In severe cases, symptoms of acute renal failure such as oliguria, anuria, and azotemia may occur. (5) Others: A few patients may have myocardial damage and arrhythmia. Ventricular fibrillation and respiratory center paralysis are mostly causes of death. (6) People with inhalation poisoning are often accompanied by symptoms of eye and upper respiratory tract irritation. Sometimes it can cause pulmonary edema. 2. Chronic poisoning Reports of chronic poisoning are relatively rare. Long-term and repeated exposure to carbon tetrachloride may cause dizziness, fatigue, insomnia, memory loss, loss of appetite, nausea, diarrhea and abdominal pain. There may be hepatomegaly and abnormal liver function. Severe cases may develop into portal cirrhosis. A small number of patients develop retrobulbar optic neuritis, resulting in reduced visual field and vision loss. In addition, there are reports abroad that it can cause hearing impairment, cochlear-vestibular system dysfunction and aplastic anemia. Long-term skin contact may cause dryness, scaling, and chapped skin due to degreasing. Acute poisoning (1) In case of acute poisoning, the patient should be removed from the scene quickly. Remove contaminated clothing. If the skin or eyes are contaminated, rinse with water or 2% sodium bicarbonate solution for at least 15 minutes. People with oral poisoning must have their stomach lavaged as soon as possible. Before gastric lavage, use liquid paraffin or vegetable oil to dissolve carbon tetrachloride. (2) The patient should rest in bed and be observed closely for 3 to 4 days. Pay attention to urine routine, urine output, blood creatinine and liver function to detect signs of liver and kidney damage early. (3) Provide early oxygen, high-calorie, high-vitamin and low-fat diet. (4) Actively prevent and treat damage to the nervous system, liver and kidney function. The treatment principles are the same as those of internal medicine. When oliguria or anuria occurs, hemodialysis or peritoneal dialysis should be performed as soon as possible to prevent and treat uremia, hyperkalemia, etc. (5) Avoid taking epinephrine and alcohol-containing drugs. (6) In recent years, it has been reported abroad that early application of ether cysteine ​​can prevent or reduce liver and kidney function damage. There are also reports that hyperbaric oxygen therapy is effective. Experimental results suggest that hyperbaric oxygen can reduce the formation of carbon tetrachloride free radicals in the liver, thereby reducing lipid peroxidation and reducing liver damage. However, there have been no domestic reports

Both substances are toxic and highly harmful. Comparing the two, trichlorethylene should be more toxic 1# ahlh2001

According to the "Classification of Hazards of Occupational Exposure to Toxic Substances" (GB5044-85), carbon tetrachloride is highly hazardous and trichlorethylene is moderately hazardous.