Crystalline Silica (Quartz)

Classification

Carcinogenicity, Category 1A (inhalation); STOT repeated exposure, Category 1 (lungs)

Hazard statements

• H350 May cause cancer by inhalation.
• H372 Causes damage to the lungs through prolonged or repeated exposure by inhalation.

Key precautionary statements

• P201 Obtain special instructions before use.
• P202 Do not handle until all safety precautions have been read and understood.
• P260 Do not breathe dust.
• P264 Wash hands thoroughly after handling.
• P270 Do not eat, drink or smoke when using this product.
• P280 Wear protective gloves, protective clothing and eye protection.
• P308+P313 IF exposed or concerned: Get medical advice or attention.
• P501 Dispose of contents and container in accordance with local regulations.

Limits apply to the respirable fraction of the dust, not to bulk sand or stone. OSHA regulates respirable crystalline silica under its own standards: 29 CFR 1910.1053 for general industry and maritime, and 29 CFR 1926.1153 for construction. Both set a PEL of 50 µg/m³ as an 8-hour TWA and an action level of 25 µg/m³, which triggers exposure assessment; medical surveillance is required for workers at or above the action level for 30 or more days a year. NIOSH treats crystalline silica as a potential occupational carcinogen and advises keeping exposure as low as possible. The ACGIH TLV of 0.025 mg/m³ is half the OSHA PEL. Where the silica standards do not apply, OSHA Table Z-3 mineral dust limits are used. State OSHA plans may set different limits.

• Appearance: Colorless to white, odorless crystalline solid; a component of sand, stone, concrete, brick and many mineral dusts
• Odor: Odorless
• Molecular weight: 60.1
• Boiling point: 4046°F (2230°C)
• Melting point: 3110°F (1710°C)
• Flash point: Not applicable (noncombustible solid)
• Explosive limits: Not applicable
• Vapor pressure: 0 mmHg (approx.)
• Specific gravity: 2.66
• Water solubility: Insoluble

Inhalation

Breathing fine (respirable) dust from cutting, grinding, drilling, crushing or abrasive blasting is the main hazard. Short-term effects include cough, shortness of breath and wheezing. Very high exposures can cause silicosis within weeks to a few years.

Skin

Not absorbed through the skin. Dust can be abrasive and mildly irritating.

Eyes

Dust irritates the eyes.

Ingestion

Not a significant route of exposure in normal use.

Target organs

Lungs and respiratory system, eyes

Long-term effects

Repeated inhalation causes silicosis, an incurable and often progressive lung scarring disease that can lead to disability and death. It also causes lung cancer and is linked to chronic obstructive pulmonary disease (COPD) and kidney disease. Silicosis raises the risk of tuberculosis, and smoking makes lung damage worse.

Gloves

The New Jersey Department of Health lists nitrile or natural rubber gloves. Use impermeable or work gloves where abrasion may occur.

Eyes and face

Safety glasses with side shields or goggles where dust is produced.

Respiratory

Control dust first with water spray, local exhaust or vacuum dust collection, as required by the OSHA silica standards. Where respirators are needed, NIOSH lists a particulate respirator with N95, R95 or P95 or better filters (not quarter-mask) up to 0.5 mg/m³; a powered air-purifying respirator with high-efficiency filter up to 1.25 mg/m³; and a full-facepiece respirator with N100, R100 or P100 filters up to 2.5 mg/m³. Use a pressure-demand SCBA for unknown concentrations.

Clothing

Disposable coveralls such as Tyvek or work clothes that are changed before leaving work. Do not clean clothing with compressed air or by shaking.

Store bagged or bulk material in closed containers in a dry place. The material itself is stable; the hazard comes from dust released when it is handled or processed.

Use wet methods, local exhaust ventilation or vacuums with HEPA filters to keep dust down. OSHA prohibits dry sweeping and dry brushing, and using compressed air to clean, where these could add to silica exposure and safer methods are feasible.

Keep away from

• Powerful oxidizers such as fluorine, chlorine trifluoride, manganese trioxide, oxygen difluoride and hydrogen peroxide
• Acetylene
• Ammonia
• Hydrofluoric acid (dissolves silica and releases toxic silicon tetrafluoride gas)

• Keep unprotected people away and avoid raising dust.
• Wear a NIOSH-approved particulate respirator, eye protection and gloves.
• Wet the material down or pick it up with a HEPA-filtered vacuum. Do not dry sweep or use compressed air.
• Place collected material in closed, labeled containers for disposal.
• Silica is not regulated as a hazardous material for transport, so no ERG guide applies.

Suitable extinguishing media

• Use the agent best suited to the surrounding fire (crystalline silica does not burn)

Special hazards

Not flammable or explosive, and it does not produce hazardous combustion products. Dust from damaged containers may still be a breathing hazard during and after a fire.

• OSHA Hazard Communication (29 CFR 1910.1200): Hazardous chemical; labels, safety data sheets and worker training required. The silica standards require training on cancer, lung, immune system and kidney effects.
• OSHA Respirable Crystalline Silica, general industry and maritime (29 CFR 1910.1053): PEL 50 µg/m³ TWA, action level 25 µg/m³, exposure assessment, regulated areas, written exposure control plan, housekeeping limits and medical surveillance.
• OSHA Respirable Crystalline Silica, construction (29 CFR 1926.1153): Same PEL and action level, with Table 1 listing specified dust controls for common tasks as an alternative to exposure monitoring.
• OSHA Mineral Dusts (29 CFR 1910.1000 Table Z-3): Applies where the silica standards are not in effect.
• CERCLA (40 CFR 302.4): Not a listed hazardous substance.
• EPCRA Sections 302 and 313 (40 CFR 355, 40 CFR 372.65): Not listed.
• DOT Hazardous Materials (49 CFR 172.101): Not regulated for transport.

• NIOSH Pocket Guide: Silica, crystalline (as respirable dust)
• OSHA 29 CFR 1910.1053 Respirable crystalline silica
• OSHA Occupational Chemical Database: Silica, crystalline
• OSHA Silica, Crystalline topic page
• NJ Department of Health Hazardous Substance Fact Sheet: Silica, quartz