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Agent Name Methyl iodide
Alternative Name Iodomethane
CAS Number 74-88-4
Formula C-H3-I
Major Category Toxic Gases & Vapors
Synonyms Iodomethane; Monoiodomethane; [NIOSH]
Category Other Toxic Gases & Vapors
Description Colorless liquid with a pungent, ether-like odor. [Note: Turns yellow, red, or brown on exposure to light & moisture.] [NIOSH]
Sources/Uses Used as a methylating agent; used in microscopy because of its high refractive index; [ACGIH]
Comments Liquid causes second degree burns after contact for a few minutes. [CHRIS] Corrosive to skin; [Quick CPC] In animal feeding studies, methyl iodide is hepatotoxic, "ten times as acutely toxic as carbon tetrachloride." After an industrial accident, an exposed chemical plant worker developed symptoms of central nervous system poisoning and died. [ACGIH] Inhalation can cause pulmonary edema, CNS depression, and death; [CAMEO] A lachrymator; [CHEMINFO] It is an acute pulmonary irritant that can cause chronic neurological symptoms after a heavy dermal exposure. [Reference #1]
Reference Link Acute methyl iodide exposure with delayed neuropsy...[Am J Ind Med. 2005] - PubMed Result
Exposure Assessment
Skin Designation (ACGIH) Yes
TIH Yes
TLV (ACGIH) 2 ppm
PEL (OSHA) 5 ppm
IDLH (NIOSH) 100 ppm
Excerpts from Documentation for IDLHs Basis for original (SCP) IDLH: The chosen IDLH is based on the mouse 57�minute LC50 of 860 ppm [Buckell 1950 cited by Patty 1963]. . . . Other animal data: In a subchronic study, no rats died following exposures to 150 ppm for 6 hours/day for 3 days [Monsanto 1986]. Human data: None relevant for use in determining the revised IDLH
Vapor Pressure 400 mm Hg
Lethal Concentration LC50 (rats) = 1,300 mg/m3/4H
Adverse Effects
Toxic Pneumonitis Yes
Dermatotoxin Skin Burns
Lacrimator Yes
Neurotoxin Other CNS Neurotoxin
Hepatotoxin Hepatotoxin, Secondary
IARC Carcinogen Not Classifiable
Links to Other NLM Databases
Health Studies Human Health Effects from Hazardous Substances Data Bank: METHYL IODIDE  
Toxicity Information Search TOXNET
Chemical Information Search ChemIDplus
Biomedical References Search PubMed
Related Information in Haz-Map
Diseases Occupational diseases associated with exposure to this agent:





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Last updated: January, 2009