Dibenzopyrenes are a group of high molecular weight

polycyclic aromatic hydrocarbon A polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings. The simplest representative is naphthalene, having two aromatic rings and the three-ring compounds anthracene and phenanthrene. ...

s with the molecular formula C₂₄H₁₄. There are five

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

s of dibenzopyrene which differ by the arrangement of

aromatic ring In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to saturat ...

s: dibenzo 'a'',''e''yrene, dibenzo 'a'',''h''yrene, dibenzo 'a'',''i''yrene, dibenzo 'a'',''l''yrene, and dibenzo 'e'',''l''yrene. Dibenzopyrenes have been recognized for their suspected human

carcinogenicity A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive sub ...

. The most notable dibenzopyrene isomer, dibenzo 'a'',''l''yrene is a constituent of

tobacco smoke Tobacco smoke is a sooty aerosol produced by the incomplete combustion of tobacco during the tobacco smoking, smoking of cigarettes and other tobacco products. Temperatures in burning cigarettes range from about 400 °C between puffs to abo ...

and is thought to be 30 to 100 times more potent as a carcinogen than benzo 'a''yrene. The four dibenzopyrene isomers; dibenzo 'a'',''e''yrene, dibenzo 'a'',''h''yrene, dibenzo 'a'',''i''yrene, dibenzo 'a'',''l''yrene are included in the list of 16 EU priority polycyclic aromatic hydrocarbons due to their

mutagenicity In genetics, a mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level. As many mutations can cause cancer in ...

and suspected human carcinogenicity. Primary sources of dibenzopyrenes in the environment are combustion of wood and coal, gasoline and

diesel exhaust Diesel exhaust is the gaseous exhaust produced by a diesel type of internal combustion engine, plus any contained particulates. Its composition may vary with the fuel type or rate of consumption, or speed of engine operation (e.g., idling or at ...

, and

tire A tire (American English) or tyre (British English) is a ring-shaped component that surrounds a Rim (wheel), wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide Traction (engineering), t ...

References

{{Reflist, 2 Polycyclic aromatic hydrocarbons