- 252.3 g/mol
- Polycyclic aromatic hydrocarbons (PAH)
Compound properties list
|Melting/boiling point|| 179 °C||Solid|
|Relative density||1.35 g/cm3||Sinks in water|
|Vapour pressure||1 x 10 -7 mm Hg||Very low volatility|
|Vapour density||8.7||Much denser than air|
|Solubility in water||0.002 mg/L||Very low solubility|
|Henry's law constant||4 x 10-7 atm·m3/mol||Slow volatilization when dissolved|
|log Koc (Depending on soil or sediment characteristics)||6.0 - 7.4*||Very strong adsorption to organic matter|
At 20 0C, benzo(a)pyrene is a solid with very low volatility. Characterized by its very
low solubility, it will volatilize slowly once dissolved and adsorbs very strongly to organic
matter. When present in soil, this compound will volatilize very lightly and solubilize very slowly.
Once dissolved, it will either migrate into the water table or drain towards a waterway, where it
will be diluted before volatilizing slowly. Fragments of benzo(a)pyrene can also be carried into and
deposited at the bottom of waterways, where they will very slowly dissolve. Once the source has
been removed, the adsorbed benzo(a)pyrene will take a very long time to disappear, being released in
its gaseous or dissolved forms. The resulting plumes (gaseous or dissolved) will be relatively small
Benzo(a)pyrene should be handled with care, as it is toxic.
Benzo(a)pyrene is a polycyclic aromatic hydrocarbon (PAH). PAHs are a group of organic
compounds that contain two or more benzene rings in their structure. There are more than 100
different PAHs that generally occur as complex mixtures (example, combustion by-products such as soot).
Incomplete combustion of fuels in engines, during coal coking, or when wood is burning (forest
fires, wood stoves) produces PAHs. PAHs are also constituents of petroleum and coal, and they are
more present in some of their derivatives like tars and asphalt. The wood preservative industry
(example, creosote), aluminum smelters using Soderberg electrodes, and hazardous waste disposal sites
are further contributors of anthropogenic PAHs to the environment.
Benzo(a)pyrene, like most individual PAHs, has very limited or no known uses, except as reagents
in biochemical or cancer research. Benzo(a)pyrene is more likely to be found mixed with other PAHs
in commercial products like coal tar, coal tar pitch, creosote, bitumen and asphalt. Coal tar is
used as a fuel in the steel industry, distilled to give coal tar pitch and creosote, and has been
used in the clinical treatment of skin disorders such as eczema and dermatitis. Coal tar pitch is
used primarily as a binder for aluminum smelting electrodes, but is also used in roofing, surface
coatings and a variety of other applications. Creosote is used to preserve wood for railroad ties,
marine pilings and telephone poles. Some creosote products are also used as a fuel by steel
production. Bitumen and asphalt are used for paving roads, for sound- and water-proofing, and
Agency for Toxic Substances and Disease Registry (ATSDR). 1995. Toxicological
Profile for Polycyclic Aromatic Hydrocarbons (PAHs). U.S. Department of Health and Human
Services, Public Health Service, Georgia, USA.
(Viewed December 2013)
Canadian Council of Ministers of the Environment. 1999. Canadian Water Quality Guidelines for
the Protection of Aquatic Life: Polycyclic Aromatic Hydrocarbons (PAHs). In: Canadian
Environmental Quality Guidelines. Canadian Council of Ministers of the Environment, Manitoba,
Canada. (Viewed December 2013).
Montgomery, John H. 2007. Groundwater Chemicals, Desk Reference, Fourth Edition, CRC
Press, Taylor and Francis Group, Florida, USA.
National Toxicology Program. 2005. Report on Carcinogens, Twelfth Edition: Substance Profile of
Polycyclic Aromatic Hydrocarbons. U.S. Department of Health and Human Services, Public Health
Services, USA.(PDF, 256KB) (Viewed December 2013)