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Substance: Osmium Tetroxide Chemical Formula: OsO₄ CAS Number: 20816-12-0 Appearance: Colorless to pale yellow crystals or volatile solid that gives off a strong, acrid smell Common Use: Often used as a staining agent in electron microscopy, and for small-scale organic synthesis Solubility: Moderately soluble in water, more soluble in organic solvents Odor Threshold: Pungent odor detectable at extremely low concentrations
Main Dangers: Highly toxic, both by inhalation and skin contact; quickly turns breathable air into a serious risk zone Hazard Statements: Oxidizer, Severe Eye and Skin Irritant, Causes Burns, Possesses Acute Toxicity, May Cause Delayed Damage to Organs Routes of Exposure: Eyes, Skin, Inhalation, Ingestion Target Organs: Eyes, Respiratory System, Skin, Kidneys Physical Hazards: Powerful oxidizer, can intensify fire; can corrode most metals Chronic Hazards: Prolonged exposure can lead to vision loss and kidney damage
Main Component: Osmium Tetroxide Purity: Often available as nearly pure substance Impurities: Minor trace metals depending on source Mixtures: Sometimes found in solution with solvents such as chloroform, but most documentation refers to pure OsO₄
Eye Contact: Flush eyes with plenty of water for at least 15 minutes, keeping eyelids open; seek emergency medical attention; avoid rubbing Skin Contact: Remove contaminated clothing, rapidly wash skin with soap and plenty of water; see a healthcare provider Inhalation: Move to fresh air immediately; call a doctor without delay; provide supplemental oxygen if breathing is affected Ingestion: Do not induce vomiting; rinse mouth with water, get urgent medical help Symptoms to Watch: Severe eye pain, blurred vision, skin blistering, difficulty breathing, coughing
Suitable Extinguishing Media: Use water spray, dry chemical, or carbon dioxide Do Not Use: Avoid direct water jets, as OsO₄ can react with organic material Fire Hazards: Not itself flammable but contributes oxygen to promote combustion of other material; toxic fumes likely during fire Firefighting Protection: Firefighters require full protective gear and self-contained breathing apparatus Thermal Decomposition: Can release toxic osmium fumes
Personal Protection: Wear chemical-resistant gloves, splash goggles, and use a respirator approved for toxic oxidizers Evacuation: Move unprotected people away, ventilate the area well Land Spill: Absorb spills with inert substance (vermiculite, clay), sweep up using tools that do not emit sparks Waste Handling: Scoop up without raising dust, place in sealed containers for hazardous disposal Decontamination: Neutralize surface with sodium sulfide or sodium thiosulfate for small spills
Safe Handling: Work within a certified fume hood, keep osmium tetroxide containers tightly closed; avoid skin, eye, and clothing contact; never open in open air Safe Storage: Store in cool, dry, well-ventilated areas; keep away from combustible materials, acids, and reducing agents; protect from direct sunlight Container Materials: Use glass or compatible plastic; reactive with most metals Signage: Clearly label containers with hazard warnings
Personal Protective Equipment: Chemical goggles or face shield, nitrile or butyl gloves, chemical-resistant suit, respirator with appropriate filter Engineering Controls: Utilize fume hoods, local ventilation to limit airborne concentrations Occupational Exposure Limit: OSHA Ceiling Limit: 0.002 mg/m³; NIOSH REL: 0.002 mg/m³ as ceiling over eight hours Hygiene Measures: Clean hands thoroughly after handling, never eat, drink, or smoke in contaminated areas
Molecular Weight: 254.23 g/mol Appearance: Crystalline solid, pale yellow color Melting Point: About 40 °C Boiling Point: Around 130 °C Vapor Pressure: Noticeable at room temperature; very volatile Solubility: Slow dissolution in water, more rapid in organic solvents Density: Approximately 4.9 g/cm³ Odor: Sharp, pungent, similar to ozone or chlorine
Chemical Stability: Stable under recommended storage; decomposes under light and heat Reactive Materials: Strong oxidizing agent, reacts violently with organic compounds, reducing agents, many metals Hazardous Decomposition Products: Osmium fumes, oxides Incompatibilities: Organic solvents, combustible materials, acids, strong bases
Acute Toxicity: Lethal at low concentrations; causes sudden severe irritation and burns Chronic Toxicity: Long-term exposure leads to loss of vision, kidney injury Symptoms of Overexposure: Eye pain, tearing, persistent cough, chest pain, watery eyes, darkened vision Mechanism of Toxicity: Binds to tissue proteins, disrupts cellular activity Cancer Risk: Studies are limited but data suggests occupational exposure increases risk to eyes and lungs
Aquatic Toxicity: Harmful to fish and invertebrates at very low concentrations Environmental Persistence: Stays in water and soil as osmium compound; potential to bioaccumulate Degradation: Does not break down easily; no known rapid biodegradation General Risks: Spills near water sources pose long-term harm to local biota
Hazardous Waste: Treat all solutions and residues as high-hazard regulated waste Disposal Practices: Collect waste in dedicated, labeled containers; neutralize with reducing agents such as sodium sulfite or thiosulfate before disposal Regulatory Status: Must comply with local, regional, and national hazardous waste disposal laws Don’t: Never pour osmium solutions down the drain or discard with regular garbage
Transport Classification: Regarded as hazardous under most international transportation guidelines UN Number: UN2471 Packaging Requirements: Leak-proof, tightly sealed in high-integrity packaging, secondary containment strongly advised Labeling: Must prominently display oxidizer and toxic hazard symbols
USA OSHA: Specifically regulated as an extremely hazardous substance EPA: Listed on hazardous substances list, strict regulations for workplace limits and environmental release EU Classification: Labeled as toxic, oxidizing, and environmentally hazardous under CLP Worker Protection: Mandates personal protection, exposure monitoring, and access control Recordkeeping: Employers required to document usage, storage, and disposal
