Naphthalene
The mothball substance — EU-banned as a consumer contact poison, present in every puff.
At a glance
- Also known as
- Naphthalin · Mottenkugel-Stoff
- CAS number
- 91-20-3
- Toxicity
High
- Carcinogenic
- Yes — IARC Group 2B
- In cigarette smoke
- 1-5 μg per cigarette (DKFZ)
- In vape aerosol
- trace amounts at high wattages
What is Naphthalene?
Naphthalene is a polycyclic aromatic hydrocarbon (PAH) and the simplest of its class — two fused benzene rings. Characteristic is its strong sweet-tarry smell, released at room temperature as sublimation vapour. The IARC classifies naphthalene as Group 2B („possibly carcinogenic to humans“).
Why is Naphthalene in cigarettes?
During incomplete combustion of tobacco components — as with benzo[a]pyrene, but smaller and more volatile — two- and three-ring PAHs form. Naphthalene is the most common representative with 1 to 5 micrograms per cigarette in the mainstream smoke (source: DKFZ). Unlike larger PAHs, naphthalene is gaseous and reaches deeper into the lung.
What Naphthalene does to your body — short term
Acutely, naphthalene irritates eyes, nose and upper airways. At higher exposure, headache, nausea, and in rare cases a haemolytic anaemia in people with glucose-6-phosphate dehydrogenase deficiency (G6PD) follow — a genetic metabolic variant affecting roughly 400 million people worldwide. These patients react to naphthalene with red-blood-cell breakdown.
What Naphthalene does long term
In chronically exposed lab animals — especially in rodent studies — nasal cavity tumours and upper airway tumours develop. Translating this to humans is the discussion basis for the IARC 2B classification. In smokers and occupationally exposed people (e.g. in coal-tar processing), exposure levels correlate with elevated airway tumour rates.
Where else do you know Naphthalene from?
You know naphthalene as the smell of classic mothballs — these have been banned in the EU for consumer sale since 2008, though they remain permitted in industrial contexts. Naphthalene also forms in diesel exhaust and is a major component of coal tar. Despite the EU ban, mothballs occasionally still appear in online retail.
How it compares
Germany's workplace exposure limit for naphthalene is 0.5 mg/m³ (AGW, TRGS 900). A cigarette releases this concentration well above the limit during direct inhalation — the exposure adds up over years with other PAH representatives, primarily benzo[a]pyrene.
Workplace exposure limit: 0.5 mg/m³ (AGW TRGS 900)
Related substances
These substances you want out of your body.
Flamy walks you through quitting, step by step.
Download the Flamy app