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Chemical Datasheet

METHYL BROMIDE AND NONFLAMMABLE, NONLIQUEFIED COMPRESSED GAS MIXTURE

2.3 - Poisonous gas

Chemical Identifiers

CAS Number UN/NA Number DOT Hazard Label USCG CHRIS Code
  • 74-83-9   (METHYL BROMIDE)
  • 1955
  • Poison Gas
none
NIOSH Pocket Guide International Chem Safety Card
Methyl bromide
  • METHYL BROMIDE
NFPA 704
Diamond Hazard Value Description
1
3 0
Blue Health 3 Can cause serious or permanent injury.
Red Flammability 1 Must be preheated before ignition can occur.
Yellow Instability 0 Normally stable, even under fire conditions.
White Special
Note: NFPA ratings shown are for methyl bromide, CAS number 74-83-9.
(NFPA, 2010)
General Description
A colorless odorless gas at room temperature and pressure. Readily liquefied by moderate pressure or by cooling to 4.5oC. A poison that causes respiratory distress and neurotoxic effects from which recovery may be slow. Often "stenched" with chloropicrin in use, which adds an irritating chloroform-like odor. Prolonged or repeated skin contact may cause severe burns and possible absorption of toxic quantities. Mixed with a non-reactive, nonflammable gas to dilute and carry for use as a fumigant. This mixture is then handled as a gas. Under prolonged exposure to fire or intense heat the container may rupture violently and rocket.

Hazards

Reactivity Alerts
none
Air & Water Reactions
Even pure methyl bromide is nonflammable over a wide range of concentrations in air. Thus this mixture presents practically no fire hazard. Slightly water soluble (NTP, 1992). Methyl bromide reacts with water to generate hydrobromic acid and methanol but the reaction is so slow that it can be disregarded for most practical purposes.
Fire Hazard
Excerpt from 123 Polymerizable warning [Gases - Toxic]:

Some may burn but none ignite readily. Vapors from liquefied gas are initially heavier than air and spread along ground. Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket. (ERG, 2020)
Health Hazard
Excerpt from 123 Polymerizable warning [Gases - Toxic]:

TOXIC; may be fatal if inhaled or absorbed through skin. Vapors may be irritating and/or corrosive. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may cause environmental contamination. (ERG, 2020)
Reactivity Profile
METHYL BROMIDE is incompatible with metals, dimethyl sulfoxide, ethylene oxide. [Lewis]. Can give flammable products if mixed with potassium hydroxide, sodium hydroxide and other strong bases. Methyl bromide in a steel tank reacted with an aluminum tube (part of the level gauge) producing methyl aluminum bromide. When the latter was subsequently exposed to air, enough heat was produced to ignite the methyl bromide-compressed air mixture above the liquid layer. The ensuing explosion shattered the tank (also incompatible with zinc, magnesium, and alloys)[Chem. Eng. Pro. 58(8). 1962]. A reaction between methyl bromide and dimethyl sulfoxide resulted in an explosion that shattered the apparatus [NFPA 491M. 1991].
Belongs to the Following Reactive Group(s)
Potentially Incompatible Absorbents

No information available.

Response Recommendations

Isolation and Evacuation
Excerpt from 123 Polymerizable warning [Gases - Toxic]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 100 meters (330 feet) in all directions.

SPILL: See ERG Table 1 - Initial Isolation and Protective Action Distances on the UN/NA 1955 datasheet.

FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2020)
Firefighting
Excerpt from 123 Polymerizable warning [Gases - Toxic]:

SMALL FIRE: Dry chemical or CO2.

LARGE FIRE: Water spray, fog or regular foam. Do not get water inside containers. If it can be done safely, move undamaged containers away from the area around the fire. Damaged cylinders should be handled only by specialists.

FIRE INVOLVING TANKS: Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. Do not direct water at source of leak or safety devices; icing may occur. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. (ERG, 2020)
Non-Fire Response
Excerpt from 123 Polymerizable warning [Gases - Toxic]:

Do not touch or walk through spilled material. Stop leak if you can do it without risk. If possible, turn leaking containers so that gas escapes rather than liquid. Prevent entry into waterways, sewers, basements or confined areas. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. Do not direct water at spill or source of leak. Isolate area until gas has dispersed. (ERG, 2020)
Protective Clothing
Excerpt from ERG Guide 123 [Gases - Toxic]:

Wear positive pressure self-contained breathing apparatus (SCBA). Wear chemical protective clothing that is specifically recommended by the manufacturer when there is NO RISK OF FIRE. Structural firefighters' protective clothing provides thermal protection but only limited chemical protection. (ERG, 2020)
DuPont Tychem® Suit Fabrics
Normalized Breakthrough Times (in Minutes)
Chemical CAS Number State QS QC SL C3 TF TP RC TK RF
Bromo methane 74-83-9 Vapor >480 >480 >480 >480
Methyl bromide 74-83-9 Vapor >480 >480 >480 >480
> indicates greater than.

Special Warning from DuPont: Tychem® and Tyvek® fabrics should not be used around heat, flames, sparks or in potentially flammable or explosive environments. Only...

(DuPont, 2023)

First Aid
EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

SKIN: CAUTION: Exposure of skin to compressed gases may result in freezing of the skin. Treatment for frostbite may be necessary. Remove the victim from the source of contamination. IMMEDIATELY wash affected areas gently with COLD water (and soap, if necessary) while removing and isolating all contaminated clothing. Dry carefully with clean, soft towels. Call a hospital or poison control center IMMEDIATELY even if no symptoms (such as inflammation or irritation) develop. Be prepared to transport the victim to a hospital for treatment after washing the affected area if advised to do so by a physician.

INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. IMMEDIATELY call a physician and be prepared to transport the victim to a hospital even if no symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to that advised under Protective Clothing.

INGESTION: This compound is a gas, therefore inhalation is the first route of exposure.

OTHER: Since this chemical is a known or suspected carcinogen you should contact a physician for advice regarding the possible long term health effects and potential recommendation for medical monitoring. Recommendations from the physician will depend upon the specific compound, its chemical, physical and toxicity properties, the exposure level, length of exposure, and the route of exposure. (NTP, 1992)

Physical Properties

Chemical Formula:
  • CH3Br
Flash Point: data unavailable
Lower Explosive Limit (LEL): 13.5 % (NTP, 1992)
Upper Explosive Limit (UEL): 14.5 % (NTP, 1992)
Autoignition Temperature: 999°F (NTP, 1992)
Melting Point: -135°F (NTP, 1992)
Vapor Pressure: 1250 mmHg at 68°F (NTP, 1992)
Vapor Density (Relative to Air): 3.3 (NTP, 1992) - Heavier than air; will sink
Specific Gravity: 1.6755 at 68°F (NTP, 1992) - Denser than water; will sink
Boiling Point: 38.41°F at 760 mmHg (NTP, 1992)
Molecular Weight: 94.94 (NTP, 1992)
Water Solubility: Slightly soluble (NTP, 1992)
Ionization Energy/Potential: 10.54 eV [From NPG: Methyl bromide] (NIOSH, 2023)
IDLH: 250 ppm ; A potential occupational carcinogen. [From NPG: Methyl bromide] (NIOSH, 2023)

AEGLs (Acute Exposure Guideline Levels)

Final AEGLs for Methyl bromide (74-83-9)
Exposure Period AEGL-1 AEGL-2 AEGL-3
10 minutes NR 940 ppm 3300 ppm
30 minutes NR 380 ppm 1300 ppm
60 minutes NR 210 ppm 740 ppm
4 hours NR 67 ppm 230 ppm
8 hours NR 67 ppm 130 ppm
NR = Not recommended due to insufficient data
(NAC/NRC, 2023)

ERPGs (Emergency Response Planning Guidelines)

Chemical ERPG-1 ERPG-2 ERPG-3
Methyl Bromide (74-83-9) NA 100 ppm 300 ppm
NA = not appropriate.
(AIHA, 2022)

PACs (Protective Action Criteria)

Chemical PAC-1 PAC-2 PAC-3
Methyl bromide; (Bromomethane) (74-83-9) 19 ppm 210 ppm 740 ppm LEL = 100000 ppm
(DOE, 2018)

Regulatory Information

EPA Consolidated List of Lists

Regulatory Name CAS Number/
313 Category Code
EPCRA 302
EHS TPQ
EPCRA 304
EHS RQ
CERCLA RQ EPCRA 313
TRI
RCRA
Code
CAA 112(r)
RMP TQ
Bromomethane 74-83-9 1000 pounds 1000 pounds 1000 pounds 313 U029
Methyl bromide 74-83-9 1000 pounds 1000 pounds 1000 pounds X U029

(EPA List of Lists, 2022)

CISA Chemical Facility Anti-Terrorism Standards (CFATS)

No regulatory information available.

OSHA Process Safety Management (PSM) Standard List

Chemical Name CAS Number Threshold Quantity (TQ)
Methyl Bromide 74-83-9 2500 pounds

(OSHA, 2019)

Alternate Chemical Names