Product Name: Hydroquinone Chemical Name: 1,4-Benzenediol Synonyms: Quinol, 1,4-Dihydroxybenzene Recommended Use: Photographic developer, polymerization inhibitor, skin depigmentation agent Supplier Information: Manufacturing address, contact phone, emergency telephone—consult product label or company website CAS Number: 123-31-9 EC Number: 204-617-8 Molecular Formula: C6H6O2
Classification: Acute Toxicity (Oral, Dermal, Inhalation), Eye Damage/Irritation, Skin Corrosion/Irritation, Germ Cell Mutagenicity, Carcinogenicity, Hazardous to the aquatic environment Pictograms: Skull and crossbones, exclamation mark, health hazard, environmental hazard Signal Word: Danger Hazard Statements: Harmful if swallowed; Causes skin irritation; May cause an allergic skin reaction; Causes serious eye damage; Suspected of causing genetic defects; May cause cancer; Very toxic to aquatic life Precautionary Statements: Avoid breathing dust or fumes; Wear protective gloves/protective clothing/eye protection/face protection; Wash skin thoroughly after handling; Do not eat, drink or smoke; Avoid release to the environment
Hydroquinone: >99% Impurities: Phenol, benzoquinone (trace) Other Components: None reported
Inhalation: Move person to fresh air immediately. Seek medical attention if respiratory symptoms develop—cough, shortness of breath. Skin Contact: Remove contaminated clothing. Rinse skin under water for at least 15 minutes. Call a physician if irritation or other symptoms persist. Eye Contact: Rinse cautiously with water for 20 minutes, keeping eyelids open. Remove contact lenses if present. Seek urgent medical care. Ingestion: Rinse mouth, never induce vomiting. Do not give anything by mouth to an unconscious person. Immediate medical attention required. Most Important Symptoms: Redness, burning sensation, severe irritation of skin and eyes, risk of allergic reaction, headache, nausea Notes for Physicians: Treat symptoms, monitor for effects from delayed absorption, allergic reactions, and possible methemoglobinemia
Suitable Extinguishing Media: Water spray, alcohol-resistant foam, dry powder, carbon dioxide Unsuitable Media: Direct water jet Special Hazards: Releases toxic fumes of carbon monoxide, carbon dioxide, benzoquinone under fire conditions Protective Equipment for Firefighters: Full protective gear and self-contained breathing apparatus Advice: Move containers from fire if safe; cool exposed containers with water spray
Personal Precautions: Avoid inhalation of dust/fumes. Ventilate area. Wear protective clothing, gloves, goggles, and, if dust is airborne, an appropriate respirator Environmental Precautions: Prevent release into sewer/stormwater systems. Avoid contaminating groundwater or soil Containment and Clean-up: Sweep or scoop up spilled material, avoid raising dust. Place in suitable, tightly closed containers for disposal. Clean area with water and detergent.
Handling: Use in a well-ventilated area. Minimize dust generation. Avoid contact with skin, eyes, clothing. Use mechanical exhaust if dust/fume levels exceed limits Storage: Keep package tightly closed in a cool, dry, well-ventilated place away from sources of ignition and strong oxidizing agents. Store under inert gas if possible to slow oxidation. Protect containers from physical damage Storage Temperature: Below 25°C, avoid heat and sunlight
Occupational Exposure Limits: OSHA PEL: 2 mg/m3 (TWA); ACGIH TLV: 2 mg/m3 (TWA) Engineering Controls: Local exhaust ventilation, closed systems Personal Protection:
Appearance: White crystalline solid Odor: Weak aromatic, phenolic Melting Point: 172°C Boiling Point: 285°C Density: 1.33 g/cm3 Solubility: Soluble in water (60 g/L at 20°C), highly soluble in alcohol, ether, acetone Vapor Pressure: 1.5 x 10-4 mmHg (25°C) pH: Slightly acidic (5.5–6 in saturated solution) Flash Point: 165°C (closed cup) Autoignition Temperature: 545°C Stability: Gradually darkens on exposure to air and light
Chemical Stability: Stable under recommended storage; oxidizes on exposure to light/air Reactivity: Reacts vigorously with strong oxidizers, strong bases Possibility of Hazardous Reactions: Polymerization not expected Hazardous Decomposition Products: Carbon monoxide, carbon dioxide, benzoquinone, phenol
Acute Toxicity: LD50 Oral–Rat: 320 mg/kg; LD50 Dermal–Rabbit: 1,200 mg/kg Routes of Exposure: Ingestion, inhalation, dermal, eye contact Symptoms: Redness, skin/eye burns, respiratory distress, allergic reactions, methemoglobinemia in severe exposures Chronic Effects: Potential mutagen, possible carcinogen in humans (IARC Group 3), skin depigmentation Sensitization: Risk of allergic dermatitis with repeated contact
Ecotoxicity: Highly toxic to aquatic organisms; LC50 (fish): 0.044 mg/L (96 hr) Persistence: Rapid biodegradation in soil/water under aerobic conditions Bioaccumulation: Low potential (log Kow 0.59) Mobility: Relatively mobile in water
Waste Disposal: Treat as hazardous chemical waste. Incinerate in approved facilities. Dispose according to local/national regulations Contaminated Packaging: Decontaminate with solvent where possible; otherwise, dispose as hazardous waste Environmental Precautions: Do not allow material to enter public sewers, surface waters, or soil
UN Number: UN2662 Proper Shipping Name: Hydroquinone Transport Hazard Class: 6.1 (Toxic Substance) Packing Group: III Marine Pollutant: Yes Special Precautions: Isolate from foodstuffs and incompatible substances; clearly mark and label containers
Classification: Complies with OSHA Hazard Communication Standard; covered by REACH Regulation (EC) No 1907/2006 SARA Title III: Listed, Section 313 (Toxic Chemicals) California Prop 65: Not listed as carcinogen but check regularly updated legislation Label Elements: Required pictograms, hazard statements, precautionary measures according to GHS Other National/International Regulations: Subject to specific workplace and environmental safety legislation; always consult latest local, state, and federal requirements
