**Abstract**

Polycyclic aromatic hydrocarbons (PAHs) formed as a result of incomplete combustion of organic compounds. It contains compounds that cause toxic, teratogenic, mutagenic and carcinogenic damage, such as heterocyclic aromatic amines, benzene and formaldehyde. PAHs can be found in industrial wastes, garbage, cigarette smoke, pesticides and flue gases and can contaminate air, water, soil and food. Although more than 100 PAH compounds are detected in nature, it is accepted that 16 PAH compounds have more harmful effects. It is important to determine the PAH exposure levels of feeds used in animal nutrition, since the contamination of feed plants and factory feeds with PAH compounds will indirectly affect human health. In this study, the physical and chemical properties of PAHs and their effects on animal production and indirectly on human health were compiled.

**Keywords:** benzo[a]pyrene, animal nutrition, exposure, polycyclic aromatic hydrocarbons (PAHs), feeds

### **1. Introduction**

Polycyclic aromatic hydrocarbons (PAHs) are pollutants generated by the pyrolysis or incomplete combustion of carbon-containing material, fossil fuels such as coal and other organic matter including food at high temperatures under oxygen-deficient conditions and are defined as organic lipophilic compounds that contain two or more benzene rings [1, 2]. The contamination of food with these compounds generally results from water, air and soil pollution, but PAHs may also be produced during food processing at high temperatures [3]. Owing to their chemical structure, PAHs have carcinogenic and mutagenic effects. The association of PAHs with cancer was first described in 1775 by Percivall Pott, surgeon of St. Bartholomew's Hospital in London, upon his diagnosis of scrotal cancer in chimney sweepers. This was the first observation of environmental factors being a possible cause of cancer. Later, scrotal cancer was also detected by Bell and Volkmann in workers employed in the paraffin manufacture industry in Germany and Scotland, and thereby, the observation of Pott was confirmed. In subsequent research on laboratory animals and humans, chemicals containing benzo[a]pyrene, such as tar, oil, smoke and fume, were identified as being rich in PAHs [4, 5]. Today, PAHs are produced either anthropogenically through industrialisation, the increased use of fossil fuels, waste deposition and tobacco consumption, or naturally, as a result of

forest and brush fires and volcanic eruptions [1, 6, 7]. In modern-day life, people are exposed to these compounds mostly through the consumption of contaminated water and food and the inhalation of polluted air. Exposure to PAHs increases with the consumption of heat-treated food as well as by smoking [2]. Three different mechanisms have been reported for the production of PAHs in food. The first involves the generation of PAHs as a result of the pyrolysis of organic matter such as carbohydrates, fat and protein at high temperatures (500–900°C) [8]. The second mechanism involves the generation of volatile PAHs as a result of the dripping of melting fat onto hot coal from food cooked on coal fire. These volatile PAHs contaminate the surface of cooked food at much higher levels with increased smoke generation. In particular, when meat is char-grilled, melting fat drips onto hot coal, resulting in pyrolysis, and the contact of grilled meat with smoke results in the accumulation of the volatile PAHs in the lipid components of the food. Owing to the lipophilic structure of PAHs, the water and fat content of food dictates the rate of transport of these compounds to food [2]. The third mechanism of PAH production is the incomplete combustion of coal, which eventually results in the contamination of the food surface with the generated pollutants [3].

After being discharged into the atmosphere, polycyclic aromatic hydrocarbons are either carried away from the source of emission or naturally settle in soil and water. The absorption of gaseous chemicals by plants is one of the main pathways of PAHs entering the Agri foodstuffs chain. Thus, PAHs enter the food chain of humans either directly, through the consumption of plant products such as cereals and vegetables, or indirectly, by the consumption of animal products such as milk and meat [4, 8]. The direct consumption of contaminated food and feed by livestock is the main course of organic pollutants entering the animal body. This results in animal products consumed by humans, such as meat and milk, being contaminated. Overall, 88–98% of cases of exposure to PAHs are foodborne [1, 8].

PAHs are contaminants which get in whole parts of the environment: atmosphere, waters and soils. This means that there is a risk that can be directly contaminated to plant and animal products. Considering this existence of PAHs and the risks for public health and animals associated with the exposures, the aim of this paper is to review and underline current information on the features, destinies and hazards associated with the presence of these compounds in the feeds and animal nutrition.
