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Chemical Datasheet

METHYL IODIDE

6.1 - Poison Inhalation Hazard

Chemical Identifiers

CAS Number UN/NA Number DOT Hazard Label USCG CHRIS Code
  • 74-88-4   (METHYL IODIDE)
  • 2644
  • Poison Inhalation Hazard
  • MIO
NIOSH Pocket Guide International Chem Safety Card
Methyl iodide
  • METHYL IODIDE
NFPA 704
data unavailable
General Description
A colorless liquid that turns brown on exposure to light. Denser than water. Contact may irritate skin, eyes and mucous membranes. Very toxic by ingestion, inhalation and skin absorption.

Hazards

Reactivity Alerts
none
Air & Water Reactions
Soluble in water. Sinks and slowly decomposes in water forming poisonous vapor cloud of HI.
Fire Hazard
Special Hazards of Combustion Products: Toxic and irritating gases are generated when exposed to fire or heat.

Behavior in Fire: Containers may explode (USCG, 1999)
Health Hazard
Inhalation of vapor causes lung congestion and pulmonary edema. Higher concentrations causes rapid narcosis and death. Contact with liquid irritates eyes and burns skin. (USCG, 1999)
Reactivity Profile
Halogenated aliphatic compounds, such as METHYL IODIDE, are moderately or very reactive. Halogenated organics generally become less reactive as more of their hydrogen atoms are replaced with halogen atoms. Low molecular weight haloalkanes are highly flammable and can react with some metals to form dangerous products. Materials in this group are incompatible with strong oxidizing and reducing agents. Also, they are incompatible with many amines, alkylphosphines, nitrides, azo/diazo compounds, alkali metals (sodium), and epoxides.
Belongs to the Following Reactive Group(s)
Potentially Incompatible Absorbents

No information available.

Response Recommendations

Isolation and Evacuation
Excerpt from 151 Polymerizable warning [Substances - Toxic (Non-Combustible)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.

SPILL: See ERG Table 1 - Initial Isolation and Protective Action Distances on the UN/NA 2644 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 151 Polymerizable warning [Substances - Toxic (Non-Combustible)]:

SMALL FIRE: Dry chemical, CO2 or water spray.

LARGE FIRE: Water spray, fog or regular foam. If it can be done safely, move undamaged containers away from the area around the fire. Dike runoff from fire control for later disposal. Avoid aiming straight or solid streams directly onto the product.

FIRE INVOLVING TANKS OR CAR/TRAILER LOADS: Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. Do not get water inside containers. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2020)
Non-Fire Response
Excerpt from 151 Polymerizable warning [Substances - Toxic (Non-Combustible)]:

Do not touch damaged containers or spilled material unless wearing appropriate protective clothing. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. Cover with plastic sheet to prevent spreading. Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers. DO NOT GET WATER INSIDE CONTAINERS. (ERG, 2020)
Protective Clothing
Excerpt from NIOSH Pocket Guide for Methyl iodide:

Skin: PREVENT SKIN CONTACT - Wear appropriate personal protective clothing to prevent skin contact.

Eyes: PREVENT EYE CONTACT - Wear appropriate eye protection to prevent eye contact.

Wash skin: WHEN CONTAMINATED - The worker should immediately wash the skin when it becomes contaminated.

Remove: WHEN WET OR CONTAMINATED - Work clothing that becomes wet or significantly contaminated should be removed and replaced.

Change: No recommendation is made specifying the need for the worker to change clothing after the workshift.

Provide:
• EYEWASH - Eyewash fountains should be provided in areas where there is any possibility that workers could be exposed to the substances; this is irrespective of the recommendation involving the wearing of eye protection.
• QUICK DRENCH - Facilities for quickly drenching the body should be provided within the immediate work area for emergency use where there is a possibility of exposure. [Note: It is intended that these facilities provide a sufficient quantity or flow of water to quickly remove the substance from any body areas likely to be exposed. The actual determination of what constitutes an adequate quick drench facility depends on the specific circumstances. In certain instances, a deluge shower should be readily available, whereas in others, the availability of water from a sink or hose could be considered adequate.] (NIOSH, 2023)
DuPont Tychem® Suit Fabrics
Normalized Breakthrough Times (in Minutes)
Chemical CAS Number State QS QC SL C3 TF TP RC TK RF
Iodomethane 74-88-4 Liquid imm 296 296 >480 >480 >480
Methyl iodide 74-88-4 Liquid imm 296 296 >480 >480 >480
> indicates greater than.
"imm" indicates immediate; having a normalized breakthrough time of 10 minutes or less.

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: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. IMMEDIATELY call a hospital or poison control center even if no symptoms (such as redness or irritation) develop. IMMEDIATELY transport the victim to a hospital for treatment after washing the affected areas.

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: DO NOT INDUCE VOMITING. Corrosive chemicals will destroy the membranes of the mouth, throat, and esophagus and volatile chemicals have a high risk of being aspirated into the victim's lungs during vomiting. Thus, the risk of increasing the medical problems by inducing vomiting of a volatile corrosive chemical is very high. If the victim is conscious and not convulsing, give 1 or 2 glasses of water to dilute the chemical and IMMEDIATELY call a hospital or poison control center. IMMEDIATELY transport the victim to a hospital. If the victim is convulsing or unconscious, do not give anything by mouth, ensure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. DO NOT INDUCE VOMITING. IMMEDIATELY transport the victim to a hospital.

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:
  • CH3I
Flash Point: data unavailable
Lower Explosive Limit (LEL): 10 % (USCG, 1999)
Upper Explosive Limit (UEL): 15 % (USCG, 1999)
Autoignition Temperature: data unavailable
Melting Point: -87.6°F (NTP, 1992)
Vapor Pressure: 661.76 mmHg (USCG, 1999)
Vapor Density (Relative to Air): data unavailable
Specific Gravity: 2.279 at 68°F (USCG, 1999) - Denser than water; will sink
Boiling Point: 108.3°F at 760 mmHg (NTP, 1992)
Molecular Weight: 141.94 (NTP, 1992)
Water Solubility: 10 to 50 mg/mL at 64°F (NTP, 1992)
Ionization Energy/Potential: 9.54 eV (NIOSH, 2023)
IDLH: 100 ppm ; A potential occupational carcinogen. (NIOSH, 2023)

AEGLs (Acute Exposure Guideline Levels)

No AEGL information available.

ERPGs (Emergency Response Planning Guidelines)

Chemical ERPG-1 ERPG-2 ERPG-3
Methyl Iodide (74-88-4) 25 ppm 50 ppm 125 ppm
(AIHA, 2022)

PACs (Protective Action Criteria)

Chemical PAC-1 PAC-2 PAC-3
Methyl iodide (74-88-4) 25 ppm 50 ppm 125 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
Methyl iodide 74-88-4 100 pounds 313 U138

(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 Iodide 74-88-4 7500 pounds

(OSHA, 2019)

Alternate Chemical Names