Methyl Isocyanate

CAS RN: 624-83-9

Health Effects

0.2.1 SUMMARY OF EXPOSURE
  • 0.2.1.1 ACUTE EXPOSURE
    • A) Methyl isocyanate (MIC) is a severe eye, skin, and mucous membrane irritant. MIC exposure, especially large doses, may produce an immunologic response. It may be absorbed through the skin. MIC and its trimer are absorbed via inhalation.
    • B) Most deaths from methyl isocyanate are a result of lung tissue damage. Cyanide poisoning does NOT occur following exposure to pure MIC, and empiric antidotal therapy is not warranted. Effects of cyanide poisoning have been noted but this is most likely due to impurities (Sax & Lewis, 1989).
    • C) Immediate and persistent respiratory symptoms occurred in about 200,000 local inhabitants of Bhopal, India following an inadvertent release of MIC in 1984. Severe irritation of the eyes, nose, and throat, choking sensation, and cough were the initial symptoms reported from these survivors. Some of those exposed became weak, fainted, and died within minutes. Defecation, urination, and vomiting with colicky abdominal pains occurred.
      • 1) Survivors sought treatment for symptoms of intense burning of the eyes, photophobia, blepharospasm, profuse lacrimation, lid edema, and superficial corneal ulceration.
      • 2) Severe dyspnea was common and considered due to focal atelectasis, local inflammation, and acute lung injury.
      • 3) Respiratory function and visual acuity has remained abnormal among the persons exposed in the Bhopal incident for at least two years (Kamat et al, 199
      • 2) and longer in those of close proximity to the 1984 accident (Cullinan & Acquilla, 1997).
0.2.3 VITAL SIGNS
  • 0.2.3.1 ACUTE EXPOSURE
    • A) Acute exposure may cause dyspnea.
0.2.4 HEENT
  • 0.2.4.1 ACUTE EXPOSURE
    • A) Contact with the eye is extremely irritating and may cause permanent damage with cataract formation, trachoma and chronic blepharitis.
0.2.6 RESPIRATORY
  • 0.2.6.1 ACUTE EXPOSURE
    • A) Low concentrations may produce mild respiratory irritation. High concentrations result in cough, dyspnea, increase secretions, chest pain, tightness and asthmatic episodes. Acute lung injury may be seen. Chronic exposures may result in chronic obstructive lung disease.
0.2.7 NEUROLOGIC
  • 0.2.7.1 ACUTE EXPOSURE
    • A) Acute lung injury-induced hypoxia may produce CNS depression.
0.2.8 GASTROINTESTINAL
  • 0.2.8.1 ACUTE EXPOSURE
    • A) Gastrointestinal irritation and vomiting may occur.
0.2.9 HEPATIC
  • 0.2.9.1 ACUTE EXPOSURE
    • A) Decreased liver function may occur.
0.2.10 GENITOURINARY
  • 0.2.10.1 ACUTE EXPOSURE
    • A) Renal tubular necrosis and edema may be noted.
0.2.11 ACID-BASE
  • 0.2.11.1 ACUTE EXPOSURE
    • A) Metabolic acidosis may occur.
0.2.13 HEMATOLOGIC
  • 0.2.13.1 ACUTE EXPOSURE
    • A) Cherry-red blood may be observed.
0.2.14 DERMATOLOGIC
  • 0.2.14.1 ACUTE EXPOSURE
    • A) Skin irritation is likely. Contact can cause chemical burns (Sittig, 1991; HSDB , 2001).
0.2.19 IMMUNOLOGIC
  • 0.2.19.1 ACUTE EXPOSURE
    • A) The immunologic system has been suggested as a mechanism of persistent respiratory and eye effects. Antibodies specific to methyl isocyanate have been demonstrated in the blood of exposed patients in Bhopal, India.
0.2.20 REPRODUCTIVE HAZARDS
  • A) There is conflicting data as to whether methyl isocyanate is fetotoxic, however, it crosses the placental barrier. Reports from Bhopal, India and animal studies suggest a high degree of adverse reproductive effects and teratogenicity.
0.2.21 CARCINOGENICITY
  • 0.2.21.1 IARC CATEGORY
    • A) IARC Carcinogenicity Ratings for CAS624-83-9 (International Agency for Research on Cancer (IARC), 2016; International Agency for Research on Cancer, 2015; IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, 2010; IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, 2010a; IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, 2008; IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, 2007; IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, 2006; IARC, 2004):
      • 1) Not Listed
  • 0.2.21.3 ANIMAL OVERVIEW
    • A) In experimental animals, no long-term neoplastic lesions were significantly associated with methyl isocyanate exposure; however, male rats had marginally increased rates of pheochromocytomas of the adrenal medulla and adenomas of pancreatic acinar cells.
0.2.22 GENOTOXICITY
  • A) Mutations were seen in S. typhimurium and mouse lymphocytes with exposure to this agent. The people exposed to methyl isocyanate during the Bhopal accident repeatedly display Robertsonian translocations. Other types of translocations involving chromosomes 5,9,11,14 and 16 have a statistically significant association with exposure to methyl isocyanate.
0.2.23 OTHER
  • 0.2.23.1 ACUTE EXPOSURE
    • A) Cholinesterase inhibition was not found in animals poisoned with methyl isocyanate.
0.2.1 SUMMARY OF EXPOSURE
  • 0.2.1.1 ACUTE EXPOSURE
    • A) A SPECIFIC REVIEW on the clinical effects and treatment of individuals exposed to this agent HAS NOT YET BEEN PREPARED. The following pertains to the GENERAL EVALUATION and TREATMENT of individuals exposed to potentially toxic chemicals.
    • B) GENERAL EVALUATION -
      • 1) Exposed individuals should have a careful, thorough medical history and physical examination performed, looking for any abnormalities. Exposure to chemicals with a strong odor often results in such nonspecific symptoms as headache, dizziness, weakness, and nausea.
    • C) IRRITATION -
      • 1) Many chemicals cause irritation of the eyes, skin, and respiratory tract. In severe cases respiratory tract irritation can progress to ARDS/acute lung injury, which may be delayed in onset for up to 24 to 72 hours in some cases.
      • 2) Irritation or burns of the esophagus or gastrointestinal tract are also possible if caustic or irritant chemicals are ingested.
    • D) HYPERSENSITIVITY -
      • 1) A number of chemical agents produce an allergic hypersensitivity dermatitis or asthma with bronchospasm and wheezing with chronic exposure.
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