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Methyl iodide

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Synonyms & Trade Names
Iodomethane, Monoiodomethane
CAS No.
74-88-4
RTECS No.
PA9450000
DOT ID & Guide
2644 151
Formula
CH₃I
Conversion
1 ppm = 5.80 mg/m3
IDLH
Ca [100 ppm]
See: 74884
Exposure Limits
NIOSH REL
Ca TWA 2 ppm (10 mg/m3) [skin] See Appendix A
OSHA PEL
TWA 5 ppm (28 mg/m3) [skin]
Measurement Methods
NIOSH 1014
See: NMAM or OSHA Methods
Physical Description
Colorless liquid with a pungent, ether-like odor. [Note: Turns yellow, red, or brown on exposure to light & moisture.]
Molecular Weight
141.9
Boiling Point
109°F
Freezing Point
-88°F
Solubility
1%
Vapor Pressure
400 mmHg
Ionization Potential
9.54 eV
Specific Gravity
2.28
Flash Point
NA
Upper Explosive Limit
NA
Lower Explosive Limit
NA
Noncombustible Liquid
Incompatibilities & Reactivities
Strong oxidizers [Note: Decomposes at 518°F.]
Exposure Routes
inhalation, skin absorption, ingestion, skin and/or eye contact
Symptoms
irritation eyes, skin, respiratory system; nausea, vomiting; dizziness, ataxia; slurred speech, drowsiness; dermatitis; [potential occupational carcinogen]
Target Organs
Eyes, skin, respiratory system, central nervous system
Cancer Site
[in animals: lung, kidney & forestomach tumors]
Personal Protection/Sanitation
(See protection codes)
Skin:Prevent skin contact
Eyes:Prevent eye contact
Wash skin:When contaminated
Remove:When wet or contaminated
Change:No recommendation
Provide:Eyewash, Quick drench
First Aid
(See procedures)
Eye:Irrigate immediately
Skin:Soap flush immediately
Breathing:Respiratory support
Swallow:Medical attention immediately
Respirator Recommendations

NIOSH

At concentrations above the NIOSH REL, or where there is no REL, at any detectable concentration:
(APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode
(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus

Escape:
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister
Any appropriate escape-type, self-contained breathing apparatus

Important additional information about respirator selection

See also
INTRODUCTION   ICSC CARD: 0509
Page last reviewed: October 30, 2019
Content source: National Institute for Occupational Safety and Health