624-83-9

colourless liquid

Methyl isocyanate is used as a chemical intermediate for the production of carbamate insecticides and herbicides. Occupational exposure to methyl isocyanate may occur in those workers who use insecticides and herbicides produced from methyl isocyanate.

ChEBI: The isocyanate that is methane modified by a single isocyanato substituent.

In organic synthesis; in manufacture of carbamate pesticides.

Highly flammable. Reacts exothermically with water to produce carbon dioxide, methylamine, dimethylurea and/or trimethylbiuret. Heat of reaction causes evolution of the vapors of the isocyanate. Reaction is relatively slow below 20°C but becomes violent at more elevated temperatures or in the presence of acids and bases.

Airborne vapors of METHYLISOCYANATE 1 X 500MG NEAT are explosive when exposed to heat, flame or sparks. Vapor may ignite on contact with strong oxidizing agents. Emits toxic fumes of nitriles and oxides of nitrogen when heated to decomposition [Lewis, 3rd ed., 1993, p. 860]. Caused the death of thousands in 1984 in Bhopal, India when released accidentally as a vapor following an exothermic reaction caused by contamination with water [Chem. Eng. News, 1985, 63(6), p. 27]. Reacts rapidly with acids and bases (including amines). May polymerize in contact with iron, tin, copper and certain other catalysts such as triphenylarsenic oxide, triethyl phosphine and tributyltin oxide. Polymerizes at elevated temperatures. Attacks some plastics, rubbers, and coatings [NTP].

METHYLISOCYANATE 1 X 500MG NEAT is a skin irritant and can cause permanent eye damage. A concentration of 2 ppm has been reported toxic in humans. METHYLISOCYANATE 1 X 500MG NEAT attacks the respiratory system, eyes and skin. It can injure the lungs and bronchial airways, cause permanent eye damage, and death. Death has been attributed to various forms of respiratory distress.

Reacts violently with water. Extremely flammable; may be ignited by heat, sparks, or flames. Vapors may travel to a source of ignition and flash back. Container may explode violently in heat of fire. Vapor explosion and poison hazard indoors, outdoors, or in sewers. Runoff to sewer may create fire or explosion hazard. When heated to decomposition, METHYLISOCYANATE 1 X 500MG NEAT emits toxic fumes of nitrogen oxides. Avoid water, acids, alkali, amines, iron, tin, copper, and other catalysts. Avoid heat, flame, oxidizers, water. Hazardous polymerization may occur. METHYLISOCYANATE 1 X 500MG NEAT (MIC) will react with water, or in the presence of catalysts (such as sodium hydroxide, sodium methoxide, triphenylarsine, triethyl phosphine, metallic chlorides) to form either a cyclic trimer (trimethyl isocyanurate) or a gummy, resinous polymer. These reactions are exothermic, producing about 540 Btu per pound of MIC. Heat produced in these reactions may result in pressure build up and rupturing of tanks.

Flammable, dangerous fire risk. Toxic byskin absorption and a strong eye and upper respira-tory tract irritant.

Exposures to methyl isocyanate are extremely toxic to humans. In Bhopal, India, in 1984, accidental exposures to methyl isocyanate caused poisoning and fatal injuries to large numbers of occupational workers as well as the general public, because of a Union Carbide gas leak. The accidental gas leakage resulted in the deaths of more than 2,000 people and adverse health effects in greater than 170,000 survivors. Pulmonary edema was the cause of death in most cases, with many deaths resulting from secondary respiratory infections such as bronchitis and bronchial pneumonia. The acute inhalation exposure to methyl isocyanate in humans caused poisoning with symptoms that include, but are not limited to, respiratory tract irritation, diffi culty breathing, blindness, nausea, gastritis, sweating, fever, chills, and liver and kidney damage. Survivors continued to exhibit damage to the lungs with bronchoalveolar lesions and decreased lung function. The damage to the eyes included loss of vision, loss of visual acuity, and cataracts. There is no report on the chronic/long-term effects of methyl isocyanate in humans or animals. Studies on animals have indicated increased incidence of fetal deaths and decreased fertility, live litter size, fetal body weight, and neonatal survival following inhalation exposure to methyl isocyanate during pregnancy.

Methyl isocyanate is used in carbamates and as chemical intermediate; in the manufacture of a wide variety of pesticides; in the production of polyurethane foams and plastics. A release of this chemical was involved in the world’s largest chemical accident, causing the death of thousands of industrial workers in 1984 in Bhopal, India.

Warning: Effects may be delayed for up to 15 hours. If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit. Medical observation is recommended for 24 to 48 hours after breathing overexposure, as pulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consider administering a drug or other inhalation therapy

UN2480 Methyl isocyanate Hazard class: 6.1; Labels: 6.1-Poison Inhalation Hazard, 3-Flammable liquid, Inhalation Hazard Zone A

Highly flammable liquid. Vapors may form explosive mixture with air. Rapid reaction in presence of acid, alkalis, amine; iron, tin, copper, their salts; or their catalysts (such as triphenylarsenic oxide, triethylphosphine, and tributyltin oxide). Exothermic reaction with water, producing carbon dioxide, highly flammable and air-reactive methylamine, dimethylurea and/or trimethyl biuret. The reaction with water is slow @ # 20C, but violent at elevated temperatures and/or in the presence of acids and bases. Elevated temperatures may cause explosive polymerization. This chemical usually contains inhibitors to prevent polymerization. Reacts with water, acids, alcohols, glycols, amines, amides, ammonia, caprolactum, caustics, strong oxidizers. Attacks some plastics, rubber or coatings. Attacks some forms of plastic, rubber and coatings

Methyl isocyanate (MIC) is an organic compound with the molecular formula CH3NCO. MIC is an extremely toxic, colorless, highly flammable liquid that evaporates quickly when exposed to the air and has a sharp, strong odor. It is hazardous to human health, and was involved in the Bhopal disaster in December 1984, which resulted in the deaths of more than 2250 individuals, with another 50 000 incapacitated, and about 100 000 treated in area hospitals.

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform to EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration in the presence of a flammable solvent. A flue gas scrubber is recommended as well.

Clear, colorless, very flammable, posionous liquid with a sharp, unpleasant, penetrating odor. Odor threshold concentration is 2.1 ppm (quoted, Amoore and Hautala, 1983).

Methyl isocyanate is reacted with 1-naphthol to produce the carbamate insecticide carbaryl and with α-methylthioisobutyrladoxime in the industrial synthesis of aldicarb.

Genetic and Related Cellular Effects Studies. Mason et al. found that methyl isocyanate did not induce mutagenic response in the Salmonella assay under test conditions. It was also negative in the Drosophila test for sex-linked recessive lethal mutations; however, it was positive in the cultured CHO cells. Mason et al. found that methyl isocyanate was positive in the mouse lymphoma assay.

Chemical/Physical. Reacts with water forming 1,3-dimethylurea and carbon dioxide. In excess water, the hydrolysis half-life is 9 min. (Castro et al., 1985)

Color Code—Blue: Health Hazard/Poison: Storein a secure poison location. Prior to working with thischemical you should be trained on its proper handling andstorage. Before entering confined space where this chemicalmay be present, check to make sure that an explosive concentration does not exist. Methyl isocyanate must be storedto avoid contact with water, acid, alkali, amines; or iron,tin, copper (or their salts); and certain other catalysts sinceviolent reactions occur. Store in tightly closed containers ina cool, well-ventilated area away from water or heat.Sources of ignition, such as smoking and open flames, areprohibited where methyl isocyanate is handled, used, orstored. Metal containers involving the transfer of 5 gallonsor more of methyl isocyanate should be grounded andbonded. Drums must be quipped with self-closing valves,pressure vacuum bungs, and flame arresters. Use only nonsparking tools and equipment, especially when opening andclosing containers of methyl isocyanate. Wherever methylisocyanate is used, handled, manufactured, or stored, useexplosion-proof electrical equipment and fittings.

Mechanisms of toxicity have still not been clearly elucidated for MIC per se. It is hypothesized that carbamylation of globin and blood proteins may be involved. Histopathologic evaluation of rodents exposed to MIC by inhalation suggest that MIC-induced injury is limited to the respiratory system. Immediate deaths most likely are a result of tissue hypoxia secondary to blockage of airways by cellular debris, mucus, and fluid. Delayed deaths most likely are caused by chronic obstructive and restrictive lung diseases. Persistent respiratory and ocular effects may also be a result of MIC-induced immunologic effects since specific antibodies have been demonstrated in the blood of exposed patients. MIC is highly reactive; therefore, the resulting onset of respiratory effects following acute exposure to MIC can be immediate in some cases. In other exposure scenarios, respiratory injury can evolve over periods of hours or days. Exposure-related deaths sometimes can occur as late as 30 or more days postexposure, due in part to the development of pneumonia. Results from human and animal studies indicate that MIC is a severe irritant to mucous membranes. Ocular irritation was the most pronounced symptom reported in human experimental studies. The most frequently reported symptoms among the exposed population in Bhopal, India, were burning of the eyes, coughing, respiratory distress from pulmonary congestion, watering of the eyes, nausea, vomiting, muscle weakness, and CNS involvement secondary to hypoxia and animal fatalities are which attributed to pulmonary edema.

The initial threshold screening level (ITSL) for methyl isocyanate is 1 μg/m3, with annual averaging time.