Material Safety Data Sheet – Magnesium Hydroxide

Identification

Product Name: Magnesium Hydroxide
Chemical Name: Magnesium Dihydroxide
Common Names: Milk of Magnesia, Magnesia
Synonyms: Hydrated Magnesium Oxide
CAS Number: 1309-42-8
Recommended Uses: Fire retardant, pharmaceutical laxative, antacid, wastewater treatment, pH control agent
Supplier/Manufacturer: Name, address, and emergency contact number should be recorded by the purchasing entity
Emergency Telephone: Local or national poison centers; Chemtrec (for US shipments): 1-800-424-9300

Hazard Identification

GHS Classification: Substance is not classified as hazardous under GHS regulations
Hazard Statements: May cause mild eye or skin irritation. Dust may cause transient respiratory discomfort.
Signal Word: None
Pictograms: None mandated
Precautionary Statements: Avoid generating dust. Use adequate ventilation in handling areas.
Potential Health Effects: Slightly irritating to eyes or mucous membranes, negligible systemic toxicity by inhalation or ingestion under normal usage.
Environment: Not considered hazardous for the environment in typical industrial or consumer use quantities.

Composition / Information on Ingredients

Chemical Identity: Magnesium Hydroxide
CAS Number: 1309-42-8
Concentration: Greater than 95% by weight
Impurities: Trace levels of calcium carbonate, silica, or other minerals depending on the source or processing

First Aid Measures

Eye Contact: Rinse cautiously with water for at least 15 minutes. Lift upper and lower lids occasionally. If irritation persists, seek medical attention.
Skin Contact: Wash thoroughly with soap and water. Remove contaminated clothing. If irritation develops, consult a healthcare provider.
Inhalation: Remove person to fresh air. Get medical attention if symptoms occur.
Ingestion: Rinse mouth. Drink water to dilute. Do not induce vomiting unless directed by medical personnel. Seek medical advice if significant quantities are swallowed.
Symptoms and Effects: Mild irritation of the eyes, possible dryness or cracking of the skin from repeated exposure, rare transient cough if dust inhaled.

Fire-Fighting Measures

Suitable Extinguishing Media: Use water spray, foam, carbon dioxide, or dry chemical for surrounding fire. Magnesium Hydroxide itself does not ignite.
Special Hazards: At very high temperatures, decomposition releases water vapor and magnesium oxide, which are not toxic.
Protective Equipment for Firefighters: Wear self-contained breathing apparatus and full protective gear if fire occurs in the vicinity.
Advice: Product acts as a flame retardant; does not propagate fire.

Accidental Release Measures

Personal Precautions: Wear appropriate personal protective equipment including gloves, safety goggles, and dust mask if dust is generated.
Environmental Precautions: Prevent large quantities from entering drains or natural waters; avoid inhaling dust.
Containment: Sweep, shovel, or vacuum material to avoid dust formation. Use non-sparking tools if necessary.
Cleanup: Dispose of collected material in accordance with local regulations. If spilled within a contained area, ensure thorough removal to avoid slip hazards or buildup.

Handling and Storage

Safe Handling: Minimize dust generation and accumulation. Use with adequate ventilation. Avoid contact with skin and eyes. Do not eat, drink, or smoke when using.
Storage Conditions: Keep in tightly closed containers, in a cool, dry, and well-ventilated area. Protect from moisture and incompatible materials such as acids and ammonium salts.
Incompatibilities: Strong acids (can cause decomposition and release of heat), ammonium salts (may react to form ammonia gas)

Exposure Controls and Personal Protection

Occupational Exposure Limits: ACGIH TLV for “Particulates Not Otherwise Regulated” – 10 mg/m³ total dust; 3 mg/m³ respirable
Engineering Controls: Use process enclosures, local exhaust ventilation to control airborne dust.
Personal Protection: Gloves (nitrile, latex), safety glasses or goggles, dust mask or NIOSH-approved respirator if dust is present in the work space.
Hygiene: Wash hands thoroughly after handling; launder contaminated clothing before reuse.

Physical and Chemical Properties

Appearance: White, odorless fine powder or slurry
Odor: Odorless
pH: 9.5–10.5 (10% slurry in water)
Melting Point: Decomposes above 350°C (662°F)
Boiling Point: Not applicable
Solubility in Water: Very slightly soluble (0.0009 g/100 mL at 18°C)
Specific Gravity: 2.36
Vapor Pressure: Not applicable
Vapor Density: Not applicable
Flash Point: Not flammable
Explosive Properties: Not explosive
Other Data: Insoluble in alcohol, soluble in ammonium salts and acids

Stability and Reactivity

Chemical Stability: Stable under normal handling and storage conditions
Reactivity: Reacts with acids to form magnesium salts, carbon dioxide may evolve with carbonate impurities.
Possible Hazardous Reactions: Contact with ammonium salts releases ammonia.
Conditions to Avoid: Exposure to strong acids, mixing with incompatible materials
Hazardous Decomposition Products: Magnesium oxide and water vapor at high temperatures.

Toxicological Information

Acute Toxicity: Oral LD50 (rat): greater than 8,500 mg/kg (practically non-toxic)
Skin Corrosion/Irritation: May cause mild irritation after repeated or extended contact.
Eye Damage/Irritation: Slight, transient irritation may occur.
Respiratory Effects: Dust may irritate upper respiratory tract; symptoms include coughing or sneezing.
Carcinogenicity: Not classified as carcinogen by IARC, NTP, OSHA.
Chronic Effects: No known long-term adverse health effects from normal exposure in occupational settings.
Sensitization: No data suggests any skin or respiratory sensitization risk.
Other Data: Formulations may cause laxative effects if ingested in large amounts.

Ecological Information

Ecotoxicity: Not harmful to aquatic life at concentrations typically used; excessive release can cause pH change in water bodies.
Persistence and Degradability: Material is inorganic; not degraded by biological processes.
Bioaccumulation: Not expected to bioaccumulate in organisms.
Mobility in Soil: Low, due to poor water solubility; binds with soil matrices.
Other Adverse Effects: Raising pH of soil or water can affect ecosystem balance if used in excess.

Disposal Considerations

Waste Methods: Collect unused or spilled material for disposal in accordance with local, regional, and national regulations. Can often be disposed as non-hazardous industrial waste.
Disposal of Containers: Rinse thoroughly before recycling or disposal. Dispose of in compliance with local requirements.
Special Precautions: Avoid large-scale disposal into waterways due to pH shift potential.

Transport Information

UN Number: Not regulated
Proper Shipping Name: Magnesium Hydroxide
Transport Hazard Class: Not hazardous
Packing Group: Not applicable
Environmental Hazards: None identified
Transport Labels: No special labeling necessary under standard international, national, or regional transport codes

Regulatory Information

TSCA Status (USA): Listed
REACH Status (EU): Registered or exempted
OSHA: Not classified as hazardous
SARA Title III: Not listed as a reportable substance
WHMIS (Canada): Not classified as hazardous
Other Regulations: Product conforms with regulations for pharmaceutical and food use where grade is appropriate; check local standards for workplace monitoring, environmental, and disposal provisions.