# NIOSH Pocket Guide to Chemical Hazards
Methyl bromide | CAS 74-83-9
CH3Br | RTECS PA4900000
Synonyms & Trade Names Bromomethane, Monobromomethane | DOT ID & Guide 1062 123
Exposure Limits | NIOSH REL: Ca See Appendix A
OSHA PEL†: C 20 ppm (80 mg/m3) [skin]
IDLH Ca [250 ppm] | Conversion 1 ppm = 3.89 mg/m3
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 | RGasD: 3.36 | Sp.Gr: 1.73 (Liquid at 32°F)
Fl.P: NA (Gas) | UEL: 16.0% | LEL: 10% |
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.]
Measurement Methods NIOSH 2520; OSHA PV2040
Personal Protection & Sanitation 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
Exposure Routes inhalation, skin absorption (liquid), skin and/or eye contact (liquid)
Symptoms Irritation eyes, skin, respiratory system; muscle weakness, 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]
See also: INTRODUCTION