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Chemical Name: Silicon Dioxide
Synonyms: Quartz, Silica, Crystalline Silica
Common Uses: Food additive, glass production, electronics, polymers, cosmetic formulations
Physical Appearance: Fine white or translucent powder, crystalline in minerals
Odor: Odorless
CAS Number: 7631-86-9
Health Risks: Inhalation of crystalline form dust can cause respiratory irritation, long-term exposure may cause silicosis, a progressive lung disease
Chronic Exposure: Extended inhalation increases risk of lung cancer and other pulmonary complications
Acute Exposure: Eyes, skin, or respiratory system may become irritated
Routes of Exposure: Inhalation, skin, eye contact
Classification: OSHA classifies respirable crystalline silica as carcinogenic; amorphous silica poses less risk
Component: Silicon Dioxide
Chemical Formula: SiO2
Purity: Often over 99% in industrial and food-grade batches
Impurities: Trace aluminum, iron, other oxides depending on source
Molecular Weight: 60.08 g/mol
Inhalation: Move person to fresh air, get medical attention if coughing or difficulty breathing persists
Eye Contact: Rinse eyes carefully with water for several minutes, remove contact lenses if present and easy, consult a physician if irritation continues
Skin Contact: Wash affected area with soap and plenty of water, medical advice should be sought for persistent irritation
Ingestion: Rinse mouth, drink water, medical attention typically unnecessary unless symptoms develop
Flammability: Non-flammable
Suitable Extinguishing Media: Use agents appropriate for surrounding fire, as SiO2 does not burn
Special Hazards: Intense heat can convert amorphous to crystalline form, generating more respirable dust
Protective Equipment: Firefighters should wear self-contained breathing apparatus if large amounts become airborne with combustion products from surroundings
Personal Protection: Wear respiratory protection and avoid generating dust
Spill Clean-up: Sweep or vacuum spilled material using equipment with HEPA filters to minimize airborne dust; avoid dry sweeping
Environmental Measures: Prevent material from entering drains, ensure proper ventilation to disperse dust particles
Safe Handling: Handle in well-ventilated spaces, use appropriate dust controls like extraction systems or respirators
Storage Conditions: Store in tightly closed containers, keep dry and out of reach of incompatible substances such as hydrofluoric acid
Good Practices: Avoid direct contact and dust generation, clean up spills efficiently, and restrict access to trained personnel
Exposure Limits: OSHA PEL for respirable crystalline silica is 50 µg/m³, ACGIH TLV is 0.025 mg/m³ as an 8-hour TWA
Engineering Controls: Local exhaust ventilation, enclosed storage, and handling systems
Personal Protective Equipment: Protective goggles, gloves, long-sleeved clothing, NIOSH-approved respirators in dust-prone areas
State: Solid
Melting Point: Over 1,600°C
Boiling Point: Above 2,200°C
Solubility: Virtually insoluble in water
Density: 2.65 g/cm³ (quartz)
Particle Size: Varies by product; nanoscale in some formulations
Other Features: Stable in air and at ordinary temperatures, very low reactivity
Chemical Stability: Silicon dioxide remains stable under normal conditions
Reactivity: Reacts with hydrofluoric acid, forming silicon tetrafluoride gas
Hazardous Polymerization: Not expected
Other Decomposition Products: None significant under regular use
Short-term Effects: Inhalation can cause transient irritation of the airway, eyes, and skin in sensitive individuals
Long-term Effects: Prolonged inhalation of respirable crystalline particles leads to silicosis, a serious irreversible lung condition with elevated cancer risk, recognized by the World Health Organization and IARC
Oral Toxicity: Very low—widely used in foods as an anti-caking agent, not absorbed in the digestive tract
Sensitization: No strong evidence for allergic response or sensitization
Persistence: Naturally abundant and inert in most environments
Bioaccumulation: Not bioaccumulative
Aquatic Toxicity: No evidence of harm to aquatic organisms when dispersed at environmental concentrations
Environmental Fate: Functions as a common mineral already present in soils, receives no special treatment in most disposal scenarios
Waste Handling: Dispose of in line with local, regional, or national regulations for non-hazardous mineral waste
Small Quantities: Place in solid waste landfill, use dust controls to prevent release
Large Quantities: consult with appropriate waste management authorities, because localized heavy dust can disrupt landfill processes or occupational exposure
UN Number: Not regulated as a hazardous material for ground, air, or sea transport
Proper Shipping Name: Silicon Dioxide
Packing Group: Not assigned
Special Precautions: Avoid damage to packaging, prevent dust dispersal during transit, use sealed containers for powders and nanoscale materials
OSHA: Enforces exposure levels for amorphous and crystalline silica in workplaces
EPA: Does not register SiO2 as a hazardous substance except in forms containing respirable crystalline silica at specific concentrations
EU REACH: Requires manufacturers to provide safety data when importing or producing large volumes annually
IARC: Lists crystalline silica inhaled in the form of quartz or cristobalite as Group 1 carcinogen; amorphous not classified as carcinogenic
Other Notes: Many countries maintain mandatory reporting or safety rules relating to airborne silica in occupational contexts, recognizing severe chronic risks for exposed populations
