September 2010

NIOSH Publication Number 2010-168c

Methyl bromide
Synonyms & Trade Names Bromomethane, Monobromomethane
CAS No. 74-83-9		RTECS No. PA4900000		DOT ID & Guide 1062 123
Formula CH₃Br		Conversion 1 ppm = 3.89 mg/m³		IDLH Ca [250 ppm] See: 74839
Exposure Limits NIOSH REL : Ca See Appendix A OSHA PEL †: C 20 ppm (80 mg/m³) [skin]				Measurement Methods NIOSH PV2040
Physical Description Colorless gas with a chloroform-like odor at high concentrations. [Note: A liquid below 38°F. Shipped as a liquefied compressed gas.]
MW: 95.0	BP: 38°F	FRZ: -137°F	Sol: 2%	VP: 1.9 atm	IP: 10.54 eV
Sp.Gr: 1.73 (Liquid at 32°F)	Fl.P: NA (Gas)	UEL: 16.0%	LEL: 10%	RGasD: 3.36
Flammable Gas, but only in presence of a high energy ignition source.
Incompatibilities & Reactivities Aluminum, magnesium, strong oxidizers [Note: Attacks aluminum to form aluminum trimethyl, which is SPONTANEOUSLY flammable.]
Exposure Routes inhalation, skin absorption (liquid), skin and/or eye contact (liquid)
Symptoms irritation eyes, skin, respiratory system; muscle weak, incoordination, visual disturbance, dizziness; nausea, vomiting, headache; malaise (vague feeling of discomfort); hand tremor; convulsions; dyspnea (breathing difficulty); skin vesiculation; liquid: frostbite; [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 (liquid) Eyes: Prevent eye contact (liquid) Wash skin: When contaminated (liquid) Remove: When wet (flammable) Change: No recommendation Provide: Quick drench (liquid)				First Aid (See procedures) Eye: Irrigate immediately (liquid) Skin: Water flush immediately (liquid) Breathing: Respiratory support
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 See ICSC CARD: 0109 See MEDICAL TESTS: 0138