IPCS INCHEM Home
METHYL MERCAPTANICSC: 0299
Methanethiol
Mercaptomethane
Methyl sulfhydrate
Thiomethanol
June 2003
CAS #: 74-93-1
UN #: 1064
EC Number: 200-822-1

  ACUTE HAZARDS PREVENTION FIRE FIGHTING
FIRE & EXPLOSION Extremely flammable.  Gas/air mixtures are explosive.  NO open flames, NO sparks and NO smoking.  Closed system, ventilation, explosion-proof electrical equipment and lighting.  Shut off supply; if not possible and no risk to surroundings, let the fire burn itself out. In other cases extinguish with powder, carbon dioxide.  In case of fire: keep cylinder cool by spraying with water. 

 STRICT HYGIENE!  
  SYMPTOMS PREVENTION FIRST AID
Inhalation Cough. Sore throat. Dizziness. Headache. Nausea. Vomiting. Unconsciousness.  Use ventilation, local exhaust or breathing protection.  Fresh air, rest. Artificial respiration may be needed. Refer for medical attention. 
Skin ON CONTACT WITH LIQUID: FROSTBITE.  Cold-insulating gloves.  Remove contaminated clothes. Refer for medical attention . ON FROSTBITE: rinse with plenty of water, do NOT remove clothes. 
Eyes Redness. Pain.  Wear safety goggles or eye protection in combination with breathing protection.  First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention. 
Ingestion      

SPILLAGE DISPOSAL CLASSIFICATION & LABELLING
Evacuate danger area! Consult an expert! Personal protection: self-contained breathing apparatus. Ventilation. Do NOT let this chemical enter the environment. 

According to UN GHS Criteria

 

Transportation
UN Classification
UN Hazard Class: 2.3; UN Subsidiary Risks: 2.1 

STORAGE
Fireproof. Separated from strong oxidants and acids. Cool. Store in an area without drain or sewer access. 
PACKAGING
Marine pollutant. 
METHYL MERCAPTAN ICSC: 0299
PHYSICAL & CHEMICAL INFORMATION

Physical State; Appearance
COLOURLESS GAS WITH CHARACTERISTIC ODOUR. 

Physical dangers
The gas is heavier than air and may travel along the ground; distant ignition possible. 

Chemical dangers
Decomposes on burning. This produces toxic fumes including sulfur oxides and hydrogen sulfide. Reacts violently with strong oxidants. Reacts with water, steam and acids. This produces flammable and toxic gas. 

Formula: CH3SH
Molecular mass: 48.1
Boiling point: 6°C
Melting point: -123°C
Relative density (water = 1): 0.9
Solubility in water, g/100ml at 20°C: 2.3
Vapour pressure, kPa at 26.1°C: 202
Relative vapour density (air = 1): 1.66
Flash point: Flammable gas
Explosive limits, vol% in air: 3.9-21.8 


EXPOSURE & HEALTH EFFECTS

Routes of exposure
The substance can be absorbed into the body by inhalation. 

Effects of short-term exposure
The substance is irritating to the eyes and respiratory tract. The substance may cause effects on the central nervous system. This may result in respiratory depression. Exposure at high levels could cause unconsciousness. Exposure at high levels could cause death. The effects may be delayed. Medical observation is indicated. 

Inhalation risk
A harmful concentration of this gas in the air will be reached very quickly on loss of containment. 

Effects of long-term or repeated exposure
 


OCCUPATIONAL EXPOSURE LIMITS
TLV: 0.5 ppm as TWA.
MAK: 1.0 mg/m3, 0.5 ppm; peak limitation category: II(2); pregnancy risk group: D 

ENVIRONMENT
The substance is very toxic to aquatic organisms. It is strongly advised not to let the chemical enter into the environment. 

NOTES
Turn leaking cylinder with the leak up to prevent escape of gas in liquid state. 

ADDITIONAL INFORMATION
  EC Classification
Symbol: F+, T, N; R: 12-23-50/53; S: (2)-16-25-60-61 

All rights reserved. The published material is being distributed without warranty of any kind, either expressed or implied. Neither ILO nor WHO nor the European Commission shall be responsible for the interpretation and use of the information contained in this material.
    See Also:
       Toxicological Abbreviations
       METHYL MERCAPTAN (JECFA Evaluation)