Polycyclic aromatic hydrocarbons (PAH)

Polycyclic aromatic hydrocarbons (PAH) are compounds made up of several condensed benzene rings with benzo(a)pyrene as the key component. The benzene rings can also carry substituents (frequently methyl groups). In a broader sense derivatives with heteroatoms are also counted among the PAHs. Altogether, several hundred compounds are known. The US Environmental Protection Agency has compiled a list of 16 especially relevant PAHs (also referred to as EPA-PAHs), divided into “light” PAHs with three to four and “heavy” PAHs with five to seven aromatic rings. PAHs are harmful to health and are classified as genotoxic carcinogens.

PAH analysis at ifp

ifp offers the detection of EPA-PAHs as a service by means of gas chromatography/tandem quadrupole (GC-MS/MS):

  • benzo(a)pyrene
  • benzo(a)anthracene
  • benzo(b)fluoranthene
  • benzo(k)fluoranthene
  • benzo(g,h,i)perylene
  • chrysene
  • dibenzo(a,h)anthracene
  • indeno(1,2,3-cd)pyrene
  • pyrene
  • fluoranthene
  • anthracene
  • phenanthrene
  • fluorene
  • acenaphthylene
  • acenaphthene
  • naphthalene.

Formation of polycyclic aromatic hydrocarbons

PAHs form as a result of incomplete combustion of organic matter such as coal or fuels and is emitted into the air and the environment via exhaust gases. They are therefore ubiquitous in the environment. Today the largest proportion of PAHs is caused by man-made activity. Frequently the ground water is heavily contaminated by waste products that accumulate as a result of coke and gas extraction from anthracite coal. However, PAHs may also form naturally, when released as a result of forest clearing or wood fires, for example.

How do PAHs get into our food?

Food may be contaminated with PAHs in the process of smoking, heating or drying, if combustion residues such as smoke come into direct contact with the food. Environmental pollution caused by crude oil accidents may also lead to food becoming contaminated with PAHs, especially fish and fishery products. High PAH concentrations are known to occur in dried fruit, olive pomace oil, smoked fish, grape seed oil, smoked meat products, fresh molluscs, spices/sauces and spice blends. Cocoa butter is also considered to be contaminated, but the contamination pathway is not yet known. The possible causes may include inappropriate production conditions (e.g. cocoa bean storage/drying on tarmaced surfaces, drying with smoke gases, open fireplaces/wood fires in the vicinity of the drying sites etc.).

Legislation regarding maximum levels for PAH in food

Maximum levels for certain foods such as smoked or grilled meat, smoked fish, oils and fats as well as baby food are regulated by Regulation (EC) No. 1881/2006.

The CONTAM Panel of the European Food Safety Authority (EFSA) concluded in 2010 that benzo(a)pyrene as a single component is not a suitable marker for the occurrence of carcinogenic PAHs in food. Instead, a sum of four carcinogenic PAHs was recommended to better protect consumer health. Hence, since 1 September 2012 benzo(a)anthracene, benzo(b)fluoranthene and chrysene have been included in the assessment and recorded together with benzo(a)pyrene as a sum parameter (group of "PAH 4“) in Regulation (EC) No. 1881/2006.

Polycyclic aromatic hydrocarbons in cocoa butter

Since April 1st, 2013, maximum levels of 5.0 µg/kg fat for benzo(a)pyrene and 35.0 µg/kg fat for the sum of PAH 4 have been in place for cocoa butter. The latter has been lowered to 30.0 µg/kg fat as of April 1st, 2015 (with a corresponding transition period to be considered).