Material Safety Data Sheet: Selenium Dioxide

Identification

Product Name: Selenium Dioxide
Chemical Formula: SeO₂
Synonyms: Selenium(IV) oxide, Selenium oxide
CAS Number: 7446-08-4
Manufacturer: Details for the supplier or manufacturer should be included on the label or request documentation.
Use: Commonly used in organic synthesis, glass manufacturing, and as a reagent in laboratory settings.
Contact Information: Emergency contact numbers and address should be listed as on label or supplier documentation.

Hazard Identification

Classification: Toxic if inhaled, harmful if swallowed, causes severe skin burns and eye damage.
Hazard Symbols: GHS05 (corrosive), GHS06 (acute toxicity).
Signal Word: Danger
Hazard Statements: H301: Toxic if swallowed; H314: Causes severe skin burns and eye damage; H331: Toxic if inhaled.
Precautionary Statements: Avoid breathing dust or vapors, avoid release to environment, wear protective gear.
Other Hazards: Skin contact can cause burns, exposure to eyes leads to serious damage, inhalation may result in respiratory distress.

Composition / Information on Ingredients

Chemical Name: Selenium Dioxide
PURITY: Typically above 99% for laboratory and industrial use
Impurities: Trace selenium compounds (may vary)
Component CAS Number: 7446-08-4
Concentration: 100% Selenium Dioxide unless stated otherwise by supplier.

First Aid Measures

Inhalation: Move person to fresh air; seek immediate medical attention if symptoms such as coughing or difficulty breathing develop.
Skin Contact: Remove contaminated clothing; rinse skin with plenty of water for at least 15 minutes; seek medical advice.
Eye Contact: Immediately flush eyes with plenty of water for at least 15 minutes, lifting upper and lower eyelids occasionally; call a physician straight away.
Ingestion: Never give anything by mouth to an unconscious person; try to rinse mouth with water and seek urgent medical attention.
Symptoms: Burning pain, redness, blistering, coughing, shortness of breath, nausea.

Fire-Fighting Measures

Suitable Extinguishing Media: Use dry chemical, CO₂, or foam; avoid water as selenium dioxide is water-soluble and runoff can cause contamination.
Specific Hazards: Selenium dioxide can evolve toxic selenium or selenium oxides under fire conditions.
Protective Equipment: Firefighters should wear self-contained breathing apparatus and protective clothing.
Explosion Data: Not an explosion hazard itself, but containers can burst if heated.
Fire-Fighting Advice: Move containers from fire area if you can do so safely; use water spray to cool fire-exposed containers to prevent rupture.

Accidental Release Measures

Personal Precautions: Avoid contact with skin and eyes; wear suitable protective equipment including gloves and eye protection.
Environmental Precautions: Prevent product from entering drains, surface water, or soil to limit environmental damage.
Methods for Cleanup: Sweep up carefully to avoid dust formation; place in a dry, closed container for proper disposal; ventilate area.
Spill Handling: Use HEPA-filtered vacuum or wet methods to reduce dust if possible; store waste in labeled, tightly sealed containers.

Handling and Storage

Handling: Work in a well-ventilated area, preferably a chemical fume hood; avoid dust formation; keep container tightly closed; do not eat, drink, or smoke in areas where this chemical is handled.
Storage: Store in a cool, dry, well-ventilated location away from moisture and incompatible substances such as strong acids or bases.
Incompatibilities: Strong acids, reducing agents.
Special Considerations: Ensure containers are clearly labeled and tightly sealed; store away from food and feedstuffs.

Exposure Controls and Personal Protection

Occupational Exposure Limits: Selenium compounds as Se: OSHA PEL 0.2 mg/m³, NIOSH REL 0.2 mg/m³.
Engineering Controls: Use local exhaust ventilation to keep airborne levels as low as possible; safety shower and eye-wash stations recommended.
Personal Protective Equipment: Suitable chemical-resistant gloves, safety goggles, lab coats, and appropriate respiratory protection if dust or vapors are present.
Hygiene Measures: Wash hands before breaks and after handling; remove contaminated clothing and wash before reuse.

Physical and Chemical Properties

Appearance: White to reddish crystalline solid
Odor: Sharp, characteristic
Melting Point: 340°C
Boiling Point: Sublimes at 315°C
Density: About 3.95 g/cm³
Solubility: Readily soluble in water, ethanol
pH (aqueous solution): Acidic
Vapor Pressure: Not established at room temperature
Partition Coefficient: Not determined
Flash Point: Not applicable
Auto-Ignition Temperature: Not applicable.

Stability and Reactivity

Chemical Stability: Stable under recommended storage and handling conditions
Conditions to Avoid: Moisture, contact with strong acids or strong bases
Incompatibles: Strong reducing agents, strong acids, metals
Decomposition Products: Toxic selenium fumes, selenium oxides
Reactivity: Reacts with water to form selenous acid; may cause corrosion to iron and steel; avoid sources of ignition.

Toxicological Information

Acute Toxicity: LD₅₀ (oral, rat): 68 mg/kg, toxic by all routes of exposure
Inhalation: Toxic, can cause severe irritation and pulmonary edema
Skin Contact: Severe burns possible, irritation, redness
Eye Contact: Severe damage, blindness is possible
Chronic Toxicity: Prolonged exposure may result in selenosis (symptoms: gastrointestinal distress, hair and nail loss, skin lesions)
Carcinogenicity: Not classified as a human carcinogen by IARC, ACGIH, NTP, or OSHA
Mutagenicity: No significant data, but selenium compounds may alter DNA synthesis in lab studies.

Ecological Information

Ecotoxicity: Very toxic to aquatic life; selenium accumulates in water and sediments
Persistence: Selenium dioxide is readily soluble and can persist in surface waters
Bioaccumulative Potential: High; selenium accumulates in living organisms, increasing risk for top predators
Mobility: Highly mobile in water, can spread rapidly if released
Environmental Precautions: Avoid uncontrolled release to water bodies and soil to prevent ecosystem disruption.

Disposal Considerations

Waste Treatment Methods: Handle as hazardous waste in line with local, regional, and national environmental regulations
Product Disposal: Do not pour down drain; collect in sealed, labeled containers for proper hazardous waste management
Contaminated Packaging: Containers that held selenium dioxide should be disposed as hazardous waste
Special Instructions: Contact licensed waste disposal authority for advice and services
Disposal of Spills: Gather as much as possible mechanically; limit dust, avoid soil and water contamination.

Transport Information

UN Number: 3283
UN Proper Shipping Name: Selenium compound, solid, n.o.s. (Selenium Dioxide)
Transport Hazard Class: 6.1 (Toxic Substances)
Packing Group: II
Environmental Hazards: Marine pollutant
Special Precautions: Ensure packaging is secure and labeling is clear; carry documentation showing hazard status and emergency contact.

Regulatory Information

OSHA: Regulated as hazardous
TSCA: Listed
EINECS: Listed (231-194-7)
SARA Title III: Listed as a toxic chemical
California Proposition 65: Not listed for cancer or reproductive toxicity
Other Regulations: Follow all applicable international, federal, state, and local regulations; check that safety documentation matches current standards.