Benzene
Banned from gasoline — present in every puff.
At a glance
- Also known as
- Benzen
- CAS number
- 71-43-2
- Toxicity
Very high
- Carcinogenic
- Yes — IARC Group 1
- In cigarette smoke
- 50-90 μg per cigarette (DKFZ)
- In vape aerosol
- trace amounts at high wattages (formed from PG/VG decomposition)
What is Benzene?
Benzene is a colourless, sweet-smelling aromatic compound and one of the most important basic chemicals in industry. The IARC has classified benzene as „carcinogenic to humans“ (Group 1) since 1987; its link to leukaemia has been scientifically established since the 1970s. In cigarette smoke it forms during the pyrolysis of organic constituents.
Why is Benzene in cigarettes?
When tobacco and paper burn, the long carbon chains of the plant fibres yield aromatic ring compounds — benzene is the simplest. Each cigarette delivers 50 to 90 micrograms of benzene to the smoker (source: DKFZ). The amount seems small, but at a pack a day it's higher than what employees at heavily exposed industrial workplaces are ever allowed to take in via protective measures.
What Benzene does to your body — short term
Acute benzene quantities from a cigarette cause no noticeable symptoms. At high concentrations — industrial accidents, tank leaks — dizziness, nausea, difficulty concentrating, and in extreme cases unconsciousness occur. But the real danger of benzene isn't acute intake — it's the years of accumulation: benzene reaches the bone marrow via the lung, where blood is formed.
What Benzene does long term
In the bone marrow, benzene damages the blood-forming stem cells. The link to acute myeloid leukaemia (AML) is best documented, but chronic lymphocytic leukaemia, lymphomas and myelodysplastic syndrome also occur. The effect is dose-dependent, but there's no safe lower threshold. Studies put tobacco smoke's share of benzene-related leukaemias in industrialised countries at 10 to 20 percent.
Where else do you know Benzene from?
Benzene was for decades a main component of shoe glues, cleaning products and gasoline — and precisely for this reason, banned or heavily restricted in most applications since the 1970s. In today's gasoline, benzene content is below 1 percent; in the EU, benzene-containing lacquers and adhesives have almost completely disappeared from the market.
How it compares
Germany's workplace acceptance concentration for benzene is 0.2 mg/m³ (TRGS 910). A pack-a-day smoker takes in roughly 1.5 milligrams of benzene daily from smoke — comparable to the maximum dose an industrial worker would absorb during 8 hours of exposure, except delivered directly into the airways without the dilution of an open workspace.
Workplace exposure limit: 0.2 mg/m³ (0.06 ppm, Akzeptanzkonzentration TRGS 910)
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