The GC-HARMS project is looking specifically at 42 petrogenic PAH, that is, PAH that occur in crude oil.

Polycyclic Aromatic Hydrocarbons (PAH), also referred to as polynuclear aromatic hydrocarbons, are  hydrocarbon molecules made of only carbon and hydrogen arranged in aromatic rings. PAH are found in crude oil and coal. PAH are also produced from the incomplete burning of organic matter; such as in fires, cooking and vehicle exhaust. Some PAH are known to cause cancer and some are suspected to cause cancer.

PAHs produced as a result of burning organic materials are referred to as Pyrogenic PAH. PAH that are found in crude oil and coal are called Petrogenic PAH.

Benzo[a]pyrene is a PAH that is found in coal tar and its ability to cause cancer has been known for a long time. Benzo[a]pyrene remains one of the most well studied PAH. The PAH found in crude oil are less well studied and a method of relating the PAH found in the GC-HARMS samples to an equivalent of Benzo[a]pyrene was used to determine their probably of causing cancer.

Sources of PAHs

For more information go to: http://www.atsdr.cdc.gov/toxfaqs/tfacts69.pdf