# NIOSH Pocket Guide to Chemical Hazards
Methyl chloride | CAS 74-87-3
CH3Cl | RTECS PA6300000
Synonyms & Trade Names Chloromethane, Monochloromethane | DOT ID & Guide 1063 115
Exposure Limits | NIOSH REL: Ca See Appendix A
OSHA PEL†: TWA 100 ppm C 200 ppm 300 ppm (5-minute maximum peak in any 3 hours)
IDLH Ca [2000 ppm] | Conversion 1 ppm = 2.07 mg/m3
Physical Description Colorless gas with a faint, sweet odor which is not noticeable at dangerous concentrations. [Note: Shipped as a liquefied compressed gas.]
MW: 50.5 | BP: -12°F | FRZ: -144°F | Sol: 0.5%
VP: 5.0 atm | IP: 11.28 eV | RGasD: 1.78 |
Fl.P: NA (Gas) | UEL: 17.4% | LEL: 8.1% |
Flammable Gas
Incompatibilities & Reactivities Chemically-active metals such as potassium, powdered aluminum, zinc & magnesium; water [Note: Reacts with water (hydrolyzes) to form hydrochloric acid.]
Measurement Methods NIOSH 1001
Personal Protection & Sanitation Skin: Frostbite Eyes: Frostbite Wash skin: No recommendation Remove: When wet (flammable) Change: No recommendation Provide: Frostbite | First Aid (See procedures) Eye: Frostbite Skin: Frostbite 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: Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, skin and/or eye contact (liquid)
Symptoms Dizziness, nausea, vomiting; visual disturbance, stagger, slurred speech, convulsions, coma; liver, kidney damage; liquid: frostbite; reproductive, teratogenic effects; [potential occupational carcinogen]
Target Organs central nervous system, liver, kidneys, reproductive system Cancer Site [in animals: lung, kidney & forestomach tumors]
See also: INTRODUCTION