Methyl iodide

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]
Biomedical References

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 57­minute 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
405 mm Hg
Lethal Concentration
LC50 (rat) = 1,300 mg/m3/4H
Explanatory Notes
VP from HSDB;
Reference Link #2
ERPG-1
25 ppm
ERPG-2
50 ppm
ERPG-3
125 ppm

Adverse Effects

Lachrymator
Yes
Toxic Pneumonitis
Yes
Neurotoxin
Other CNS neurotoxin
Hepatotoxin
Hepatoxic (a) from occupational exposure (secondary effect) or (b) in animal studies or in humans after ingestion
Dermatotoxin
Skin burns
IARC Carcinogen
Not classifiable

Diseases, Processes, and Activities Linked to This Agent

Diseases

Occupational diseases associated with exposure to this agent: