Naphthalene

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

Naphthalene is used as insect and moth repellent.

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

Exposure Limit	Limit Values	HE Codes	Health Factors and Target Organs
OSHA Permissible Exposure Limit (PEL) - General Industry See 29 CFR 1910.1000 Table Z-1	10 ppm(50 mg/m³) TWA	HE3	Cataracts, jaundice, bloody urine, kidney and liver damage
		HE7	Headache, tiredness, confusion Target organs: Brain, central nervous system
		HE12	Haemolytic anaemia
		HE14	Marked eye and skin irritation
OSHA PEL - Construction Industry See 29 CFR 1926.55 Appendix A	10 ppm(50 mg/m³) TWA	HE3	Cataracts, jaundice, bloody urine, kidney and liver damage
		HE7	Headache, tiredness, confusion Target organs: Brain, central nervous system
		HE12	Haemolytic anaemia
		HE14	Marked eye and skin irritation
OSHA PEL - Shipyard Employment See 29 CFR 1915.1000 Table Z-Shipyards	10 ppm(50 mg/m³) TWA	HE3	Cataracts, jaundice, bloody urine, kidney and liver damage
		HE7	Headache, tiredness, confusion Target organs: Brain, central nervous system
		HE12	Haemolytic anaemia
		HE14	Marked eye and skin irritation Target organs: Eyes, skin
National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)	10 ppm(50 mg/m³) TWA 15 ppm(75 mg/m³) STEL	HE3	Jaundice, blood in urine, renal shutdown, optical neuritis, corneal damage
		HE7	Headache, confusion, excitement Target organs: Brain, central nervous system
		HE14	Eye irritation
American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) (2001)^*	10 ppm(52 mg/m³) TWA 15 ppm(79 mg/m³) STEL Skin; A4	HE3	Ocular toxicity (cataracts, optical neuritis, lens opacities, retinal degeneration), jaundice, renal failure
		HE7	Headache Target organs: Brain, central nervous system
		HE12	Haemolytic anaemia
		HE14	Marked eye and respiratory tract irritation
CAL/OSHA PELs	10 ppm(50 mg/m³) TWA 15 ppm (75 mg/m³)STEL	HE3	Ocular toxicity (cataracts, optical neuritis, lens opacities, retinal degeneration), jaundice, renal failure
		HE7	Headache Target organs: Brain, central nervous system
		HE12	Haemolytic anaemia
		HE14	Marked eye and respiratory tract irritation

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.