[Physical and chemical properties] Formaldehyde is the common name formic aldehyde. Under normal temperature and pressure, it is a colorless, irritating flammable gas. Soluble in water, alcohol and other polar solvents. Its 37% aqueous solution is commonly known as "formalin." Formaldehyde is chemically active, easily reacts with other chemicals, and can polymerize itself. Often methanol is added to the formaldehyde solution as a stabilizer.
[Occupational Contact] Industrial exhaust gas, automobile exhaust, and photochemical smog that produce or use formaldehyde; Formaldehyde is widely used in construction materials, wood preservation, leather processing, papermaking, dyes, pharmaceuticals, and paints. It is mainly used in the manufacture of resins, plastics and rubbers in the industry and is widely used as a disinfection and antisepsis agent and fumigant in agriculture, forestry, animal husbandry, cosmetics, detergent and detergent production, medicine and food industry. Clothing fabrics generally contain formaldehyde; in addition, foods may have excessive concentrations of formaldehyde.
[Toxicokinetics] Formaldehyde is easily absorbed through the respiratory tract and the gastrointestinal tract and absorbed through the skin. Absorbed formaldehyde is quickly oxidized to formic acid in the body, and most of it is further oxidized into carbon dioxide and exhaled through the exhaled air. A small amount in the form of formate is excreted by the urine via the kidneys. Formaldehyde is rapidly metabolized, and occupational exposure of workers to formaldehyde from the respiratory tract generally does not increase the concentration of formaldehyde in the blood. Formaldehyde has a strong irritant effect on skin mucous membranes, and repeated exposure to formaldehyde solution can cause allergic dermatitis.
[Pathogenesis] Formaldehyde is a chemical with extremely active chemical properties and biological activity. It can bind to various biological macromolecules in the body. The irritating effects of formaldehyde on tissues may be related to the action of proteins and amino acids. Formaldehyde as a hapten binds to proteins in the epidermis and activates T lymphocytes, which can cause type IV hypersensitivity when exposed again, manifesting as allergic contact dermatitis. The acidosis that occurs after a large amount of oral administration of formaldehyde is related to the rapid metabolism of formic acid in the body. There are methanol and other stabilizers in industrial formaldehyde, and it should be noted that the toxic effects of methanol are also present.
Recent studies on formaldehyde mutagenicity and carcinogenicity have shown that formaldehyde reacts easily with intracellular nucleophiles to form adducts and can cause DNA-protein cross-linking, leading to DNA damage.
[Clinical manifestation]
1. Acute inhalation poisoning: after inhalation of formaldehyde vapor, light can cause conjunctivitis, keratitis, trachea and bronchitis, manifested as eye burning, tearing, runny nose, sore throat, cough, shortness of breath, lung auscultation and dryness Sexual rales can cause systemic symptoms such as dizziness, headache, and fatigue. In severe cases, throat and laryngeal edema occur. A small amount of inhaled formaldehyde solution may present with pneumonia, pulmonary edema and respiratory distress.
2. Acute Oral Poisoning: After taking formaldehyde solution by mistake, there is a burning sensation in the digestive tract, erosion of the oral mucosa, pain in the upper abdomen, bloody vomit, and sometimes accompanied by diarrhea and blood in the stool. Followed by dizziness, headache, irritability, convulsions, trismus, and some appear drowsiness, fatigue. Severe cases of esophageal and gastrointestinal mucosal erosions, ulcers and perforation, difficulty breathing, and more may have shock, coma, metabolic acidosis and liver and kidney damage. Adult oral lethal formaldehyde solution is 30 ~ 60ml, the main cause of death is respiratory and circulatory failure.
3, skin damage: Formaldehyde is a stimulant poison, has irritant effects on the skin and mucous membranes, can produce acute irritant dermatitis, allergic dermatitis and urticaria. Due to coagulation of the protein, exposure to high concentrations of the solution can cause coagulative necrosis of the skin. The skin rash of formaldehyde contact dermatitis is mainly clustered with red papules from miliary to rice grains. The surrounding skin is flushed or slightly red and itchy. The skin lesions were mainly in the flexor and forearm of the forearm, followed by the facial, neck, upper arms, and flexion of the lower limbs, and sometimes the armpits, groin, etc. were also invaded. Repeated exposure to long-term can still cause dry skin, chapped, palm hyperkeratosis, chronic eczema, pigmentation and so on.
[Diagnosis and differential diagnosis] Occupational acute formaldehyde poisoning is a systemic disease caused by eye and respiratory system damage caused by exposure to higher concentrations of formaldehyde gas in occupational activities in the short term.
Diagnostic principles: According to occupational history of exposure to higher concentration of formaldehyde gas in the short term, clinical manifestations of acute damage to the eye and respiratory system and chest x-ray findings, refer to on-site labor hygiene survey results, comprehensive analysis, and rule out other causes Similar diseases can be diagnosed.
Stimuli: Symptoms include transient eye and upper respiratory tract irritation, no positive lung signs, and no chest X-ray findings.
Mild poisoning: one of the following conditions: a) with obvious eye and upper respiratory tract irritation symptoms, signs of conjunctival hyperemia, edema, lungs breath sound rough, there may be scattered dry, wet? Ray examination has increased lung markings, thickening. The above performance is consistent with acute tracheobronchitis; b) One to two degrees of laryngeal edema.
Moderate poisoning: one of the following: a) persistent cough, expectoration, chest tightness, dyspnea, dry, wet lungs, rashes, rashes, or spotted patches. The above performance is consistent with acute bronchial pneumonia; b) tertiary laryngeal edema. Blood gas analysis is mild to moderate hypoxemia.
Severe poisoning: one of the following: a) pulmonary edema; b) quadrutic laryngeal edema. Blood gas analysis showed severe hypoxemia.
[Handling principles] No special antidotes, mainly symptomatic and supportive treatment. The specific measures are as follows;
1. People with acute inhalation poisoning should quickly remove the poisoned patients to fresh air, remove the contaminated clothing in time, thoroughly wash the contaminated skin with soapy water and plenty of water, and splash into the eyes immediately flush with plenty of water. Patients with upper respiratory tract irritants should observe at least 48 hours to avoid aggravation of the disease after the activity.
2, lying, warm, reasonable oxygen therapy. Keep airway open, give bronchial spasms, and tracheotomy if necessary. Early, adequate and short-term use of glucocorticoids can effectively prevent laryngeal edema and pulmonary edema.
3, after oral administration can be carefully inserted into the small gastric tube gastric lavage, gastric lavage when the action should be gentle, so as not to increase the damage of the digestive tract. After gastric lavage with 3% ammonium carbonate or 15% ammonium acetate 100ml solution into the stomach, make formaldehyde into a less toxic six subunit four amines, have a detoxification effect. Then oral milk or soy milk or egg white to protect the gastric mucosa.
4, active symptomatic treatment: including rehydration, anti-shock, prevention of liver and kidney damage and prevention of secondary infection and other complications.
5. Immediately after contact with the skin and eyes, rinse thoroughly with plenty of water and check for any corneal damage with fluorescein staining. Atropine was used to dilate pupils to prevent post-iris adhesions and local and systemic anti-inflammatory treatment. Do not use sulfa drugs to prevent the formation of insoluble formate in the renal tubules and cause urine closure.
[prevention]
The manufacture, use and transportation of formaldehyde, as well as the manufacture and use of formaldehyde-containing products should be mechanized, sealed, and enhanced ventilation and local exhaust. Production workers should pay attention to personal protection and personal hygiene and prevent direct skin contact. Do a good job of employment and regular medical examinations. All those who have chronic respiratory diseases, systemic skin diseases, chronic eye diseases, and allergies to formaldehyde should be classified as professional contraindications.
[Occupational Contact] Industrial exhaust gas, automobile exhaust, and photochemical smog that produce or use formaldehyde; Formaldehyde is widely used in construction materials, wood preservation, leather processing, papermaking, dyes, pharmaceuticals, and paints. It is mainly used in the manufacture of resins, plastics and rubbers in the industry and is widely used as a disinfection and antisepsis agent and fumigant in agriculture, forestry, animal husbandry, cosmetics, detergent and detergent production, medicine and food industry. Clothing fabrics generally contain formaldehyde; in addition, foods may have excessive concentrations of formaldehyde.
[Toxicokinetics] Formaldehyde is easily absorbed through the respiratory tract and the gastrointestinal tract and absorbed through the skin. Absorbed formaldehyde is quickly oxidized to formic acid in the body, and most of it is further oxidized into carbon dioxide and exhaled through the exhaled air. A small amount in the form of formate is excreted by the urine via the kidneys. Formaldehyde is rapidly metabolized, and occupational exposure of workers to formaldehyde from the respiratory tract generally does not increase the concentration of formaldehyde in the blood. Formaldehyde has a strong irritant effect on skin mucous membranes, and repeated exposure to formaldehyde solution can cause allergic dermatitis.
[Pathogenesis] Formaldehyde is a chemical with extremely active chemical properties and biological activity. It can bind to various biological macromolecules in the body. The irritating effects of formaldehyde on tissues may be related to the action of proteins and amino acids. Formaldehyde as a hapten binds to proteins in the epidermis and activates T lymphocytes, which can cause type IV hypersensitivity when exposed again, manifesting as allergic contact dermatitis. The acidosis that occurs after a large amount of oral administration of formaldehyde is related to the rapid metabolism of formic acid in the body. There are methanol and other stabilizers in industrial formaldehyde, and it should be noted that the toxic effects of methanol are also present.
Recent studies on formaldehyde mutagenicity and carcinogenicity have shown that formaldehyde reacts easily with intracellular nucleophiles to form adducts and can cause DNA-protein cross-linking, leading to DNA damage.
[Clinical manifestation]
1. Acute inhalation poisoning: after inhalation of formaldehyde vapor, light can cause conjunctivitis, keratitis, trachea and bronchitis, manifested as eye burning, tearing, runny nose, sore throat, cough, shortness of breath, lung auscultation and dryness Sexual rales can cause systemic symptoms such as dizziness, headache, and fatigue. In severe cases, throat and laryngeal edema occur. A small amount of inhaled formaldehyde solution may present with pneumonia, pulmonary edema and respiratory distress.
2. Acute Oral Poisoning: After taking formaldehyde solution by mistake, there is a burning sensation in the digestive tract, erosion of the oral mucosa, pain in the upper abdomen, bloody vomit, and sometimes accompanied by diarrhea and blood in the stool. Followed by dizziness, headache, irritability, convulsions, trismus, and some appear drowsiness, fatigue. Severe cases of esophageal and gastrointestinal mucosal erosions, ulcers and perforation, difficulty breathing, and more may have shock, coma, metabolic acidosis and liver and kidney damage. Adult oral lethal formaldehyde solution is 30 ~ 60ml, the main cause of death is respiratory and circulatory failure.
3, skin damage: Formaldehyde is a stimulant poison, has irritant effects on the skin and mucous membranes, can produce acute irritant dermatitis, allergic dermatitis and urticaria. Due to coagulation of the protein, exposure to high concentrations of the solution can cause coagulative necrosis of the skin. The skin rash of formaldehyde contact dermatitis is mainly clustered with red papules from miliary to rice grains. The surrounding skin is flushed or slightly red and itchy. The skin lesions were mainly in the flexor and forearm of the forearm, followed by the facial, neck, upper arms, and flexion of the lower limbs, and sometimes the armpits, groin, etc. were also invaded. Repeated exposure to long-term can still cause dry skin, chapped, palm hyperkeratosis, chronic eczema, pigmentation and so on.
[Diagnosis and differential diagnosis] Occupational acute formaldehyde poisoning is a systemic disease caused by eye and respiratory system damage caused by exposure to higher concentrations of formaldehyde gas in occupational activities in the short term.
Diagnostic principles: According to occupational history of exposure to higher concentration of formaldehyde gas in the short term, clinical manifestations of acute damage to the eye and respiratory system and chest x-ray findings, refer to on-site labor hygiene survey results, comprehensive analysis, and rule out other causes Similar diseases can be diagnosed.
Stimuli: Symptoms include transient eye and upper respiratory tract irritation, no positive lung signs, and no chest X-ray findings.
Mild poisoning: one of the following conditions: a) with obvious eye and upper respiratory tract irritation symptoms, signs of conjunctival hyperemia, edema, lungs breath sound rough, there may be scattered dry, wet? Ray examination has increased lung markings, thickening. The above performance is consistent with acute tracheobronchitis; b) One to two degrees of laryngeal edema.
Moderate poisoning: one of the following: a) persistent cough, expectoration, chest tightness, dyspnea, dry, wet lungs, rashes, rashes, or spotted patches. The above performance is consistent with acute bronchial pneumonia; b) tertiary laryngeal edema. Blood gas analysis is mild to moderate hypoxemia.
Severe poisoning: one of the following: a) pulmonary edema; b) quadrutic laryngeal edema. Blood gas analysis showed severe hypoxemia.
[Handling principles] No special antidotes, mainly symptomatic and supportive treatment. The specific measures are as follows;
1. People with acute inhalation poisoning should quickly remove the poisoned patients to fresh air, remove the contaminated clothing in time, thoroughly wash the contaminated skin with soapy water and plenty of water, and splash into the eyes immediately flush with plenty of water. Patients with upper respiratory tract irritants should observe at least 48 hours to avoid aggravation of the disease after the activity.
2, lying, warm, reasonable oxygen therapy. Keep airway open, give bronchial spasms, and tracheotomy if necessary. Early, adequate and short-term use of glucocorticoids can effectively prevent laryngeal edema and pulmonary edema.
3, after oral administration can be carefully inserted into the small gastric tube gastric lavage, gastric lavage when the action should be gentle, so as not to increase the damage of the digestive tract. After gastric lavage with 3% ammonium carbonate or 15% ammonium acetate 100ml solution into the stomach, make formaldehyde into a less toxic six subunit four amines, have a detoxification effect. Then oral milk or soy milk or egg white to protect the gastric mucosa.
4, active symptomatic treatment: including rehydration, anti-shock, prevention of liver and kidney damage and prevention of secondary infection and other complications.
5. Immediately after contact with the skin and eyes, rinse thoroughly with plenty of water and check for any corneal damage with fluorescein staining. Atropine was used to dilate pupils to prevent post-iris adhesions and local and systemic anti-inflammatory treatment. Do not use sulfa drugs to prevent the formation of insoluble formate in the renal tubules and cause urine closure.
[prevention]
The manufacture, use and transportation of formaldehyde, as well as the manufacture and use of formaldehyde-containing products should be mechanized, sealed, and enhanced ventilation and local exhaust. Production workers should pay attention to personal protection and personal hygiene and prevent direct skin contact. Do a good job of employment and regular medical examinations. All those who have chronic respiratory diseases, systemic skin diseases, chronic eye diseases, and allergies to formaldehyde should be classified as professional contraindications.
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