Polycyclic aromatic hydrocarbons

June 2015

PAHs are a group of relatively stable lipophilic organic substances containing two or more aromatic rings.

They are primarily formed during incomplete combustion or breakdown of organic matter at high temperatures and during various industrial processes.

In food preparation, PAHs may be formed in a number of food processing and domestic preparation steps including barbecuing, grilling, roasting, smoking, drying, baking, frying, and toasting.

PAHs are classified as contaminants and regulated under Commission Regulation (EC) No 1881/2006.

The purpose of this document is to provide an overview on PAHs, formation and occurrence in foods, public health significance, legislation, methods of detection, and industry good practices.

Further background and information can be found in the references.

What are Polycyclic Aromatic Hydrocarbons (PAHs)?

PAHs consist of carbon and hydrogen with two or more aromatic ring structures.  Hydrocarbons are organic compounds consisting of carbon and hydrogen. The term aromatic refers to the compound containing a cyclic structure as typified by benzene.  Poly refers to two or more aromatic rings. The presence of aromatic rings gives these compounds enhanced stability.

There are over 600 known PAH structures. The most commonly known are those of public health significance.

Generally PAHs tend to have a high melting and boiling point with low vapour pressure and low water solubility. They are lipophilic and accumulate in lipid tissue over time.

Formation of PAHs

PAHs are primarily formed during incomplete combustion or breakdown of organic matter at high temperatures and during various industrial processes. They can also be formed in natural processes such as carbonisation.

In food preparation, PAHs may be formed in a number of food processing and domestic preparation steps including barbequing, grilling, roasting, smoking, drying, baking, frying, and toasting.

Occurrence of PAHs in Foodstuffs
 
The main routes of exposure are through the environment, food processing and preparation.

The introduction of PAHs into food from the environment can occur through a wide variety of sources including stubble burning, motor vehicle and aircraft exhausts, industrial plants, wood preservation, domestic heating, tyre burning, tobacco smoke, oil pollution, forest fires, and volcanoes.

Raw unprocessed foods should not contain significant levels unless there has been environmental contamination.

Processing and heating of foods are major sources of PAH introduction. PAHs have been found in a wide variety of foods including smoked meat and fish, barbecued meat, and vegetable oils. Levels found tend to be linked to the amount of fatty tissue, temperature, and duration of heating.

For those food groups assessed by EFSA as being most at risk, regulatory maximum levels have been established in commission regulation (EC) No 1881/2006.

Public health significance

Many PAHs have shown to be exhibit immunotoxicity, genotoxicity, carcinogenicity, reproductive toxicity, and may influence development of atherosclerosis.

Legislation

High levels of PAHs in foods would lead to that specific food not meeting the food safety requirements as set out in Regulation (EU) No 178/2002.

Due to their negative public health impact and historical levels of occurrence in certain food groups, PAHs are considered a contaminant and have maximum regulatory levels of acceptance established

For more information on current regulatory levels, refer to the Contaminants in Food (England) Regulations 2013 and Section 6 of the Annex to Commission Regulation (EC) No. 1881/2006. Section 6 of the Annex names the specific foodstuffs with maximum acceptable regulatory levels which must be met before placing foods into the market.

Annex to Regulation (EC) No. 1881/2006 Section 6 has been amended by Commission Regulation (EC) No. 835/2011 published on 19 August 2011 following a conclusion by the EFSA CONTAM panel that benzo(a)pyrene alone is not a suitable indicator for the occurrence of PAHs in food. The revised legislation is based on the 4 substances benzo(a)pyrene, benzo(a)anthracene, benzo(b)fluoranthene, and chrysene, known collectively as PAH4. The separate maximum level for benzo(a)pyrene is retained to ensure comparability of previous and future data, but this may be reassessed in the future.

The revised regulatory levels apply from 1 September 2012. For certain food groups there are further tiered changes. Refer to the legislation for more information.

 

Detection

The accepted methods of sampling and analysis are laid down in Commission regulation (EC) No 333/2007.

Sampling methodology is important in order to ensure representative samples are taken which will lead to meaningful results.
The method of analysis must meet the specific requirements of the performance criteria as defined in Table 7.

When performing analysis for official control purposes, the "fitness-for-purpose" approach may be used to assess the suitability of the method of analysis. Methods suitable for official control must produce results with standard measurement uncertainties less than the maximum standard measurement uncertainty calculated using the formula in section C.3.3.2 of Commission regulation (EC) No 333/2007.

Part D of Commission regulation (EC) No 333/2007 covers the reporting and interpretation of results.

There are various methods of detection in the market place for PAH analysis.

 

Industry good practices

In HACCP, assess the likelihood of PAHs being present, introduced, or developing. Where a hazard does exist ensure controls are in place to meet regulatory limits. They are considered a chemical hazard.

In cases where PAHs may be formed during processing, review and redesign operations to minimize PAH formation.

Where present in raw material streams review and assess PAH minimization.

Removal of the outer layer of vegetables and fruits and washing can reduce PAH levels, as concentrations tend to be higher on the external tissue when present.

PAHs can be introduced from environmental sources, during direct drying and smoking operations. Codex has produced a code of practice for the reduction of contamination of food with PAH from smoking and direct drying processes.

 

References

1. IUPAC Gold Book  http://goldbook.iupac.org/
2. National Institute of Standards and Technology http://www.nist.gov/mml/analytical/organic/upload/SP-922-Polycyclic-Aromatic-Hydrocarbon-Structure-Index-3.pdf
a. Report of PaH structures.
3. EFSA Evaluation of public health significance http://www.efsa.europa.eu/en/efsajournal/pub/724.htm
4. WHO evaluation on health http://www.euro.who.int/__data/assets/pdf_file/0015/123063/AQG2ndEd_5_9PAH.pdf
5. JECFA evaluation http://www.inchem.org/documents/jecfa/jeceval/jec_1941.htm
6. EFSA Occurrence of PAHs http://ec.europa.eu/food/fs/sc/scf/out154_en.pdf
7. EU regulatory levels  http://ec.europa.eu/food/food/chemicalsafety/contaminants/pah_en.htm
Commission regulation (EC) No 1881/2006.
8. UK regulation http://www.legislation.gov.uk/uksi/2007/210/contents/made
The Contaminants in Food (England) Regulations 2007
9. Accepted methods of sampling and analysis are laid down in Commission regulation (EC) No 333/2007.             
http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2007:088:0029:0038:EN:PDF
10. JRC Technical Notes Version 3 2010 includes information on analytical methods in various food groups http://irmm.jrc.ec.europa.eu/EURLs/EURL_PAHs/about_pahs/Documents/JRC%2060146_Factsheet%20PAH_3rd%20edition.pdf
11. CODEX Code of practice for the reduction of contamination of food with PAH from smoking and direct drying processes.
http://www.codexalimentarius.net/download/standards/11257/CXP_068e.pdf

The Institute takes every possible care in compiling, preparing and issuing the information contained in IFST Information Statements, but can accept no liability whatsoever in connection with them. Nothing in them should be construed as absolving anyone from complying with legal requirements. They are provided for general information and guidance and to express expert professional interpretation and opinion, on important food-related issues.

The Institute takes every possible care in compiling, preparing and issuing the information contained in IFST Information Statements, but can accept no liability whatsoever in connection with them. Nothing in them should be construed as absolving anyone from complying with legal requirements. They are provided for general information and guidance and to express expert professional interpretation and opinion, on important food-related issues.