What is Naphthalene?

Naphthalene (C₁₀H₈) is the simplest polycyclic aromatic hydrocarbon (PAH). It is a white crystalline solid with a strong, characteristic odour detectable at concentrations as low as 0.08 ppm. As a flammable organic compound, naphthalene consists of two fused benzene rings.

The primary source of naphthalene is coal tar, a by-product of coal distillation. It is also produced during the burning of fossil fuels, wood, and tobacco, making it a common component of cigarette smoke and vehicle exhaust.

What is Naphthalene Used for?

Naphthalene is widely used in industrial and commercial applications, including:

Chemical Production

• Phthalic Anhydride: Used to make plastics, resins, and dyes
• Naphthalene Sulfonates: Used in detergents, dyes, and rubber processing
• Tetrahydronaphthalene & Decahydronaphthalene: Used as low-volatility solvents

Household & Industrial Applications

• Mothballs & Insect Repellents: Toxic to moths and larvae
• Concrete & Plasterboard Additives: Acts as a plasticizer
• Leather Tanning Agents
• Dispersants in Pesticides, Dyes, and Rubber

Other Uses

• Pyrotechnics & Special Effects: Creates black smoke and explosions
• Creosote Component: Used as a wood preservative
• Heat Transfer Studies: Used for mass sublimation experiments

Sources & Routes of Exposure

Sources of Exposure

• Air pollution: Emitted from vehicle exhaust, industrial discharge, burning wood, and tobacco smoke
• Moth repellents: Direct exposure from mothballs or treated fabrics
• Drinking water: Contamination from industrial waste

Routes of Exposure

• Inhalation: Breathing contaminated air or smoke
• Skin Contact: Touching moth-treated fabrics or contaminated surfaces
• Ingestion: Accidental swallowing of contaminated water

Health Risks of Naphthalene

Acute Effects

Short-term exposure to naphthalene can cause:

• Hemolytic Anemia: Destruction of red blood cells
• Liver Damage & Neurological Effects: Particularly dangerous for infants
• Symptoms: Headache, nausea, vomiting, diarrhea, confusion, and jaundice
• Eye Damage: Cataracts in high-exposure cases

Chronic Effects (Non-Cancer)

Long-term exposure may lead to:

• Lung & Nasal Inflammation: Observed in inhalation studies
• Eye Damage: Cataracts and retinal degeneration
• EPA Reference Limits:
  • RfC: 0.003 mg/m³ (airborne exposure)
  • RfD: 0.02 mg/kg/day (ingestion)

Reproductive & Developmental Effects

• Maternal exposure (e.g., sniffing mothballs) linked to hemolytic anemia in newborns

Cancer Risk

• Limited human data: Occupational exposure linked to laryngeal and gastrointestinal cancers
• Animal studies: Certain coal tar contaminants were carcinogenic, but pure naphthalene was not
• EPA Classification: Group C: Possible Human Carcinogen

Safety

First Aid Measures

• Eye Contact: Flush eyes with water for 15 minutes; seek medical help
• Skin Contact: Wash thoroughly with soap and water; remove contaminated clothing
• Inhalation: Move to fresh air; seek immediate medical attention if breathing difficulty occurs
• Ingestion: Do not induce vomiting; seek emergency medical help

Handling & Storage

• Store away from heat, flames, and oxidizing agents
• Keep containers tightly closed in a cool, ventilated area
• Avoid inhaling dust or fumes
• Use grounding for equipment to prevent static discharge

Exposure Controls & Personal Protection

Engineering Controls

• Local exhaust ventilation to minimize airborne exposure
• Process enclosures to prevent dust accumulation

Personal Protective Equipment (PPE)

Use the following personal protective equipment when handling naphthalene:

• Splash goggles
• Lab coat
• Dust respirator (be sure to use an approved/certified respirator or equivalent) 
• Gloves

Personal Protection in Case of a Large Spill:

• Splash goggles
• Full suit
• Dust respirator
• Boots
• Gloves
• A self-contained breathing apparatus should be used to avoid inhalation of the product. 

Note: suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this product.

Regulations

United States

Australia

Safe Work Australia: For naphthalene, the eight-hour time weighted average (TWA) exposure limit is 10 ppm or 52mg/m3. The short term exposure limit (STEL) concentration should not to exceed 15ppm or 79mg/m3.