## 1 Introduction  
Polycyclic aromatic hydrocarbons (PAHs) are a large group of highly lipophilic organic molecules with two or more fused aromatic rings [1; 2]. They contain only carbon and hydrogen atoms, unlike their parent category of polycyclic aromatic compounds (PACs). PACs include PAHs and their functional derivatives (alkyl), amino, chloro, cyano, hydroxyl, or thiol moieties) and may contain nitrogen, oxygen, or sulfur atoms in the aromatic structure (heteroatom PAHs) [3]. Given the limited state of knowledge regarding toxicological data on PACs, additional evaluation is required in order to provide an improved understanding of their toxicity [4]. PAHs are environmental and food-processing contaminants with suspected or confirmed carcinogenic properties [5; 6]. Their conformational patterns, along with the respective ring number, determine, in a highly dependent manner, their physical and chemical properties [2]. Classification-wise, PAHs are generally divided based on their number of aromatic rings. As such, compounds containing two to four rings are classified as light PAHs (LPAHs) and are associated with increased (extremely high) volatility but low toxicity. Compounds with more than four rings are heavy PAHs (HPAHs), which are less volatile but more stable and exhibit higher toxicity [1; 2; 7]. In addition to unsubstituted PAH molecules, increasing attention has been given to PAH derivatives, which are perceived to exert greater toxicity than their precursor PAHs. These include substitutions on the aromatic ring and other groups of molecules, such as larger PAHs, alkylated PAHs, and/or compounds containing heteroatoms [8; 9; 10; 11; 12]. When considering their toxicity, a great deal of information is accessible. As a summary of PAHs' \"history\" in terms of analysis, research was initiated in the context of industrial sources of PAHs through environmental studies [2; 4; 7; 13]. Consequently, their migration to crops and food was found to be of great concern. Subsequently, regulatory bodies put in place guidelines with regard to the extent of their toxicity. In 1979, the United States Environmental Protection Agency (US-EPA) established a list of 16 PAHs that are considered priority pollutants. Later on (in 2008), given a series of analytical improvements, the 16 PAHs constituting the US-EPA list were deemed not representative enough for the entire PAH profile [2; 8; 13]. Accordingly, the European Food Safety Authority (EFSA) updated the list to align with the latest advances in the state of knowledge of toxicology [14]. The resulting EU 15+1 PAHs were established following a comprehensive exposure reassessment study (over 10,000 food samples from 18 European countries) and delineate the replacement of 8 LPAHs with another 8 HPAHs that manifest increased toxicity (Figure 1) [2; 13; 15]. PAHs are ubiquitous in the environment and are mainly generated from natural sources, including diagenetic processes (changes in sediments converting into rock) and anthropogenic sources (combustion of organic matter such as coal, wood, and vegetation) [2; 3]. Consequently, PAH transport over long distances is accounted for by their airborne environmental contamination, enabled through their adsorption onto atmospheric particles, as well as their direct deposition onto soil and plants [2; 16; 17]. Moreover, PAHs undergo transformation processes in the environment over long periods, involving degradation reactions such as oxidation, nitration, and halogenation [10; 12; 17; 18]. As PAHs are exposed to light in the environment, they may undergo photochemical processes. Oxidation reactions generate oxygenated PAHs and quinones [19], as well as photodegradation products upon extended photooxidation, while nitro-PAHs result from  
Figure 1: Structures of main polycyclic aromatic hydrocarbons (PAHs) in food. US-EPA PAH16—priority compounds regulated by the United States Environmental Protection Agency; EU-EFSA PAH(15+1)—priority compounds regulated by the European Food Safety Authority.