Hydrogen selenide is a colorless gas with an offensive odor. It is highly flammable and toxic. It may be irritating to eyes and mucous membranes. It is heavier than air. Long term exposure to low concentrations or short term exposure to high concentrations can result in adverse health effects from inhalation. If exposed to prolonged fire or intense heat the containers may violently rupture or rocket.

Rate of onset: Immediate

Persistence: Minutes - hours

Odor threshold: 0.3 ppm

Source/use/other hazard: Metals &semiconductor preparation; highly flammable/explosive; can cause burns/frostbite; decomposes rapidly to form elemental selenium

• Highly Flammable

Highly flammable. Soluble in water.

It is extremely flammable; may be ignited by heat, sparks, or flames. Vapors may travel to a source of ignition and flash back. Container may explode in heat of fire. It is dangerous and forms explosive mixtures with air. It can decompose into toxic fumes. Incompatible with acid, water, halogenated hydrocarbons, oxidizers, hydrogen peroxide, and nitric acid. It should be stored out of the direct rays of the sun. Keep away from heat and flames. (EPA, 1998)

It is a hazardous compound which can cause damage to the lungs and liver. Those experiencing dermatitis, chronic bronchitis, or any form of skin allergy or respiratory tract infection are at a greater risk. (EPA, 1998)

HYDROGEN SELENIDE is a colorless, flammable gas of unpleasant odor, a deadly poison by inhalation. It forms explosive mixtures with air. It reacts vigorously with strong oxidizing reagents, e.g., hydrogen peroxide, nitric acid [Sax, 9th ed., 1996, p.1843].

• Sulfides, Inorganic
• Reducing Agents, Strong

No information available.

Excerpt from ERG Guide 117 [Gases - Toxic - Flammable (Extreme Hazard)]:

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 2202 datasheet.

FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions. (ERG, 2020)

Isolate for 1/2 mile in all directions if tank car or truck is involved in fire. Stay upwind; keep out of low areas. Withdraw immediately in case of rising sound from venting safety device or any discoloration of tank due to fire. Wear self-contained breathing apparatus and full protective clothing. Cool containers that are exposed to flames with water until well after the fire is out.

Let tank car, tank truck, or storage tank burn unless leak can be stopped. Small fires: dry chemical or carbon dioxide. Large fires: water spray, fog, or foam. (EPA, 1998)

Excerpt from ERG Guide 117 [Gases - Toxic - Flammable (Extreme Hazard)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. 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. If possible, turn leaking containers so that gas escapes rather than liquid. Prevent entry into waterways, sewers, basements or confined areas. Isolate area until gas has dispersed. Consider igniting spill or leak to eliminate toxic gas concerns. (ERG, 2020)

Excerpt from NIOSH Pocket Guide for Hydrogen selenide:

Skin: FROSTBITE - Compressed gases may create low temperatures when they expand rapidly. Leaks and uses that allow rapid expansion may cause a frostbite hazard. Wear appropriate personal protective clothing to prevent the skin from becoming frozen.

Eyes: FROSTBITE - Wear appropriate eye protection to prevent eye contact with the liquid that could result in burns or tissue damage from frostbite.

Wash skin: No recommendation is made specifying the need for washing the substance from the skin (either immediately or at the end of the work shift).

Remove: WHEN WET (FLAMMABLE) - Work clothing that becomes wet should be immediately removed due to its flammability hazard (i.e., for liquids with a flash point <100°F).

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

Provide: FROSTBITE WASH - Quick drench facilities and/or eyewash fountains should be provided within the immediate work area for emergency use where there is any possibility of exposure to liquids that are extremely cold or rapidly evaporating. (NIOSH, 2023)

Normalized Breakthrough Times (in Minutes)

Chemical	CAS Number	State	QS	QC	SL	C3	TF	TP	RC	TK	RF
Hydrogen selenide	7783-07-5	Vapor							>480	>480	>480

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)

Signs and Symptoms of Hydrogen Selenide Exposure: Acute exposure to hydrogen selenide may include garlic odor of the breath, metallic taste, dizziness, weakness, fatigue, nausea, and vomiting. Bluing of skin, irritation of the eyes, nasal secretion, pain in the chest, difficulty in breathing, coughing, irritation of the respiratory tract resulting in bronchitis and pulmonary edema may also occur. In addition, CNS depression, hypotension (low blood pressure), cardiopulmonary arrest, and coma may also be observed.

Emergency Life-Support Procedures: Acute exposure to hydrogen selenide may require decontamination and life support for the victims. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination.

Inhalation Exposure:
1. Move victims to fresh air. Emergency personnel should avoid self-exposure to hydrogen selenide.
2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer 100% humidified oxygen or other respiratory support.
3. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
4. Transport to a health care facility.

Dermal/Eye Exposure:
1. Remove victims from exposure. Emergency personnel should avoid self-exposure to hydrogen selenide.
2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer 100% humidified oxygen or other respiratory support.
3. Remove contaminated clothing as soon as possible.
4. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes.
5. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
6. Transport to a health care facility.

Ingestion Exposure:

Note: Ingestion of hydrogen selenide gas is not expected to be a significant route of exposure.
1. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer 100% humidified oxygen or other respiratory support.
2. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
3. Transport to a health care facility. (EPA, 1998)

• DIHYDROGEN MONOSELENIDE
• DIHYDROGEN SELENIDE
• HYDROGEN SELENIDE
• HYDROGEN SELENIDE, ANHYDROUS
• SELANE
• SELENIUM ANHYDRIDE
• SELENIUM DIHYDRIDE
• SELENIUM HYDRIDE
• SELENIUM HYDRIDE (H2SE)