On the degree of danger of hydrogen cyanide and protection methods

This is my scanned and converted version; it’s quite detailed. Hydrogen cyanide; Hydrogen cyanide; Hydrocyanic acid; Hydrocyanic acid; Prussic acid; CAS: 74-90-8 Physical and chemical properties: Hydrocyanic acid is a colorless liquid, while hydrogen cyanide is a colorless gas; both have a slight bitter almond odor. Molecular formula C-H-N. Molecular weight 27.03. Relative density 0.69. Melting point –14°C. Boiling point 26°C. Flash point –17.8°C. Vapor density is 0.94. Vapor pressure 101.31 kPa (760 mmHg at 25.8°C). The vapor-air mixture **should be between 6% and 41%**. Soluble in water and ethanol; slightly soluble in ether. The aqueous solution is weakly acidic. Contact opportunities: It is mainly used in the manufacture of synthetic fibers and plastics, cyanides and nitrites; in electroplating (for copper, gold, silver plating); in mining for the extraction of gold and silver; as a chelating agent; and as a fumigant to kill rodents and other insects. There have also been cases of accidental ingestion of hydrocyanic acid. Route of exposure: Poisoning mainly occurs through ingestion or inhalation. The liquid can be absorbed through the skin and conjunctiva, leading to poisoning. Introduction to Toxicology: It can be absorbed into the human body through various routes. If a non-lethal dose is absorbed, part of it is exhaled in its original form; most of the cyanide ions can be gradually released from cytochrome oxidase in body cells or from their binding to methemoglobin. Under the action of thiocyanic acid in the body, they combine with thiosulfate ions to form relatively non-toxic thiocyanates, which are then excreted in the urine. Toxicity data: Human oral LDL0: 570 μg/kg; human inhalation TCL0: 500 mg/m3•3 min; human inhalation LCL0: 120 mg/m3•1 h, 200 mg/m3•10 min, 400 mg/m3•2 min; 300 mg/m3 results in immediate death; human subcutaneous LDL0: 1 mg/kg; human intravenous TDL0: 55 μg/kg. The skin absorbs vapor at a concentration of 6760 mg/m3 for 50 minutes without any symptoms; absorption occurs at a concentration of 1230 mg/m3. The olfactory threshold ranges from 0.22 to 5.71 mg/m3. At levels of 20–40 mg/m3, mild symptoms such as headache, nausea, vomiting, and palpitations appear after a few hours. IDLH: +50 ppm. Pathogenesis: It is primarily due to cyanide ions binding to the trivalent iron in oxidized cytochrome c oxidase, thereby blocking the electron transfer of trivalent iron during the oxidation process; this prevents tissue cells from utilizing oxygen, resulting in internal asphyxiation. Clinical manifestations mainly cause asphyxia in body tissues. Acute poisoning progresses rapidly with no apparent incubation period. The condition is generally critical. Inhalation of high concentrations of hydrogen cyanide or ingestion of large amounts of hydrocyanic acid leads to immediate loss of consciousness and cessation of breathing, resulting in death within a few minutes (sudden death). Severe cases rather than sudden death cases: Early symptoms include irritation of the eyes and upper respiratory tract in those who inhaled the substance, with an almond-like odor in their exhaled breath; those who swallowed it experience a burning sensation in the mouth and throat, drooling, and vomiting, with the vomit having an almond-like odor. There are also headaches, dizziness, chest tightness, deepened and accelerated breathing, elevated blood pressure, palpitations, increased pulse rate, and the skin and mucous membranes turn bright red. Later, there was a feeling of pressure in the chest, difficulty breathing, and blurred consciousness. Subsequently, there are convulsions, coma, slowed breathing, decreased blood pressure, cyanosis, generalized muscle relaxation, respiratory arrest, a weak and irregular pulse, cardiac arrest, and death. Venous blood is bright red. The level of urinary thiocyanate may increase. Patients with mild symptoms may experience headache, dizziness, fatigue, chest tightness, difficulty breathing, palpitations, nausea, vomiting, and other symptoms. Skin or eye contact with hydrogen cyanide can cause burns. It can also absorb toxins. Diagnostic principles and differential diagnosis: Diagnosis is primarily based on the history of exposure and clinical manifestations. In the early stages of poisoning, an almond-like odor in the exhaled breath or vomit, along with bright red skin, mucous membranes, and venous blood, are characteristic signs that aid in diagnosis; however, cyanosis may occur in cases of respiratory distress. The levels of thiocyanate in blood and urine can serve as indicators of exposure; they are affected by smoking and diet, so local normal values should be taken into consideration. In cases of poisoning, the onset is sudden, and it is not possible to wait for test results before making a diagnosis. It should be differentiated from sudden death or coma caused by poisoning due to other reasons, cerebrovascular diseases, myocardial infarction, etc. Treatment: General treatment principles: Immediately remove the affected person from the area to a place with fresh air. CPR for the sudden death victim should be performed immediately. Acute poisoning progresses rapidly, and antidotes should be administered immediately on site. Oxygen is administered to the person who inhaled it. Those whose skin has come into contact with the liquid should immediately remove the contaminated clothing and rinse the skin with running water or 5% sodium thiosulfate for at least 20 minutes. Those with eye contact should rinse their eyes with saline, cooled boiled water, or clean water for 5 to 10 minutes. For those who took it orally, gastric lavage is performed using 0.2% potassium permanganate or 5% sodium thiosulfate. Detoxification method: See. Skin or eye burns are treated as acid burns. Standard workshop air hygiene standards: China’s MAC is 0.3 mg/m3; in the United States, OSHA’s PEL-TWA is 11 mg/m3 for hydrocyanic acid, and 5 mg/m3 for hydrogen cyanide; NIOSH’s REL-C is 5 mg/m3 (maximum value over 10 minutes)

Thank you, Xiao Wei. It still doesn’t seem to be very complete