Material Safety Data Sheet (MSDS) – Hydrophobic Fumed Silica

Identification

Product Name: Hydrophobic Fumed Silica
Chemical Family: Silicon dioxide, modified surface
Synonyms: Amorphous silica, surface-modified silica
CAS Number: 67762-90-7
Manufacturer: Supplier-specific; details vary by sourcing agent
Recommended Uses: Used as a thickening, anti-caking, or reinforcing agent in industrial, coatings, adhesives, and composites sectors
Emergency Contact: Refer to supplier’s immediate 24-hour hotline for emergencies concerning large-scale exposure or accidental mixing

Hazard Identification

GHS Classification: Not classified as hazardous by OSHA under 29 CFR 1910.1200, but dust can cause physical irritation
Pictogram: None required
Signal Word: None
Hazard Statements: Dust inhalation may cause temporary mild respiratory tract discomfort, eye irritation, and dryness of skin
Precautionary Statements: Avoid breathing dusts; wear appropriate protection in industrial settings; wash hands after use
Potential Health Effects: Prolonged or repeated exposure to airborne dust can worsen pre-existing lung conditions, such as asthma or bronchitis
Environmental Hazards: No long-term aquatic or terrestrial harm evidenced under usual handling, though accumulation of bulk dust can temporarily coat ground or water surfaces

Composition / Information on Ingredients

Chemical Identity: Hydrophobic fumed silica
CAS Number: 67762-90-7
Content: 100% surface-treated amorphous silica; organic treatment agents (such as dimethyldichlorosilane) may make up trace levels under 2%
Impurities: No hazardous impurities present in typical commercial forms

First Aid Measures

General Guidance: Do not leave exposed individual unattended; seek medical attention if symptoms persist
Inhalation: Move person to fresh air; assist breathing if necessary using trained personnel; obtain medical advice for persistent cough or discomfort
Skin Contact: Wash with mild soap and water; apply emollient if dryness or irritation develops
Eye Contact: Rinse carefully using gentle water stream for at least fifteen minutes, holding eyelids open; remove contact lenses beforehand if present and easy; see specialist if irritation remains
Ingestion: Rinse mouth thoroughly with water; seek medical attention if discomfort develops, though ingestion of small amounts generally does not lead to acute toxicity

Fire-Fighting Measures

Suitable Extinguishing Media: Use media suitable for surroundings; powder does not ignite but packaging or nearby combustibles may burn
Specific Hazards: Fine particles may disperse in air but do not form explosive mixtures; silica will not burn
Protective Equipment for Firefighters: Standard fire gear, including self-contained breathing apparatus, recommended due to potential release of toxic decomposition products from packaging
Special Procedures: Move product containers from fire area if safe; prevent entry of runoff or water to sewers

Accidental Release Measures

Personal Precautions: Wear dust mask (P2 or N95 standard), safety glasses, and gloves to prevent eye, skin, and respiratory irritation during cleanup
Environmental Precautions: Prevent migration of dust to watercourses, drains, and soil by dampening with water spray; silica is persistent but not harmful to aquatic systems in small accidental amounts
Cleanup Methods: Avoid dry sweeping; vacuum with HEPA-filtered industrial unit or use damp mop to minimize airborne dust; collect in suitable containers for disposal as non-hazardous waste

Handling and Storage

Handling: Avoid generating airborne dust by transferring gently; use local exhaust ventilation in enclosed or high-volume settings; do not eat, drink, or smoke in handling areas
Storage Conditions: Keep containers tightly closed in cool, dry, and well-ventilated place; store away from humidity and incompatible strong acids or alkalis
Packaging Materials: Approved bags or drums constructed from moisture-resistant, non-combustible materials; labeling in accordance with workplace safety codes
Specific Use Considerations: Limit amounts handled in open form; install spill control matting or barriers in areas with routine powder movement

Exposure Controls and Personal Protection

Occupational Exposure Limit (OEL): 10 mg/m³ (inhalable fraction), 3 mg/m³ (respirable fraction) as recommended for nuisance dusts; varies by jurisdiction
Engineering Measures: Local exhaust ventilation; general area dilution ventilation for routine use; dust containment or extraction at point of use recommended for large-scale industrial processes
Personal Protection Equipment (PPE): NIOSH-approved respirators for dust-generating tasks, chemical-resistant gloves, safety goggles, protective clothing
Hygiene Measures: Wash hands and exposed skin after handling; remove contaminated clothing and wash before reuse

Physical and Chemical Properties

Appearance: White, finely divided, lightweight powder
Odor: Odorless
pH: 3.5–5.5 (at 40 g/l H₂O, 20°C); slightly acidic due to surface treatment
Melting Point: >1700°C (amorphous silica base)
Boiling Point: Not applicable
Flash Point: Not applicable, does not support combustion
Flammability: Not flammable
Solubility: Practically insoluble in water and common solvents
Bulk Density: 30–80 kg/m³, depending on grade
Partition coefficient: Not applicable
Vapor Pressure: Not applicable
Vapor Density: Not applicable

Stability and Reactivity

Chemical Stability: Stable under recommended storage and handling conditions
Reactivity: Not reactive with ambient air, water, or most chemicals except strong acids or alkalis, which can degrade surface functional groups
Hazardous Reactions: No hazardous polymerization or violent reactions documented; generation of heat or gases unlikely
Conditions to Avoid: Prolonged exposure to strong acids, bases, or high humidity; incompatibility with hydrofluoric acid
Decomposition Products: None under normal use; high-temperature combustion of packaging may release CO, CO₂, or other organics tied to surface treatments

Toxicological Information

Acute Toxicity: Extremely low oral, dermal, and inhalation toxicity; no evidence of acute health effects at expected occupational exposures
Skin Corrosion/Irritation: Mild drying or irritation with repeated or prolonged contact
Eye Damage/Irritation: Mechanical irritation from fine powder possible; not corrosive
Respiratory Sensitization: Inhalation of dust can cause transient cough, throat irritation, or slight shortness of breath, especially in individuals with pre-existing lung diseases
Chronic Toxicity: No evidence of carcinogenicity, mutagenicity, or reproductive toxicity in available scientific data; does not contain crystalline silica above detection limits
Additional Information: No long-term health effects reported from normal industrial or laboratory use over several decades

Ecological Information

Ecotoxicity: Not acutely toxic to aquatic or terrestrial organisms in test scenarios; environmental persistence does not lead to bioaccumulation
Mobility: Immobile in solid form, settles quickly in water; high dust in runoff may cause mechanical impacts (turbidity) temporarily
Degradability: Chemically inert and resists degradation
Bioaccumulation Potential: No data indicate accumulation in biological systems, does not concentrate in food chains
Other Adverse Effects: Large spills may temporarily disrupt surface microhabitats, with no chemical toxicity

Disposal Considerations

Waste Handling: Collect residual powder and contaminated packaging in sealable containers for local solid waste landfill or industrial disposal sites
Disposal Methods: Standard landfill safe for non-hazardous industrial waste; avoid repeated releases to air or drains
Regulatory Waste Status: Not classified as hazardous or special waste under majority of local and federal regulations
Recycling Options: Industrial users may recover excess as a process thickener or reinforcing additive, minimizing waste

Transport Information

UN Number: Not regulated for transport
Proper Shipping Name: Not classified as dangerous goods
Transport Hazard Class: None
Packing Group: None
Labeling Requirements: Product label for identification; not a hazardous material
Additional Transport Precautions: Avoid handling methods that generate significant airborne dust in confined transport vehicles

Regulatory Information

U.S. TSCA Status: Listed
OSHA: Considered a nuisance dust; subject to general dust control measures
EU REACH Status: Registered as an existing substance; subject to safety data sheet provision under Article 31
Canada DSL/NDSL: Listed, non-restricted
SARA Title III: Not a hazardous substance under Sections 302, 304, or 313
Other Regulations: No California Proposition 65 substances; not on international restricted or banned chemical lists as of current review