###### Abstract  
The aim of this work was to collect and harmonize the results of several studies achieved over the years, in order to obtain a database of georeferenced observations on polycyclic aromatic hydrocarbons (PAHs) in Western and Central Mediterranean seafood. For each observation, some information on the taxonomy and the ecology of the sampled species are reported, as well as details on the investigated hydrocarbon, and spatial and temporal information on sampling. Moreover, two health risk indexes were calculated for each record and included in the database. Through several statistical methods, we conducted a meta-analysis of the data on some of the species in this database, identifying trends that could be related to the biology of the investigated organisms, as well as to the physico-chemical properties of each hydrocarbon and to the oceanographic characteristic of this part of the Mediterranean. The analysis of the data showed that, at a consumption rate like the one typical of the Italian population, seafood caught from the area considered in the present work seems to pose a minimal risk to health. However, we also found evidence of an increasing trend of PAH concentrations in Mediterranean mussels, pointing to the need for constant monitoring. eurmental pollutants; polycyclic aromatic hydrocarbons; seafood; Mediterranean Sea; Adriatic Sea; Ionian Sea; Tyrrhenian Sea; database; meta-analysis; contaminants +
Footnote †: journal: Medical Imaging and Biomedicine and Biomedicine  
molecular weight (MMW) PAHs, and those made of five or more rings are referred to as high molecular weight (HMW) PAHs [3]. In the marine environment, MMW- and HMW PAHs are mostly pyrolytic in their origin, while LMW PAHs are from petrogenic sources [7,8]. From a chemical point of view, LMW- and HMW PAHs behave differently, with MMW PAHs showing intermediate behavior. In particular, HMW PAHs are much less insoluble in water, and so they tend to bind organic particulate matter, being less bioavailable for their uptake from the water. Despite this, they can still be absorbed by aquatic organisms from sediments and particulate matter present in the water column [3,9]. For non-smokers, the major source of exposure to PAHs is diet; seafood, along with cereals, is a major contributor to the dietary intake of these compounds in Europe [10]. In 2011, the EU set the maximum allowable levels of benzo(a)pyrene (BaP) and of the sum of four HMW PAHs (PAH4; i.e., benzo(a)anthracene BaA, chrysene Chr, benzo(b)fluoranthene BbF, and BaP) in several fishery products (Table 1) [11]. Several factors could affect PAHs concentrations in seafood. As already mentioned, physico-chemical properties of PAHs influence their bioavailability, HMW PAHs being less available for uptake from the water, compared to LMW and MMW PAHs. Moreover, in fish, HMW PAHs are readily excreted, thanks to their fast metabolism, whose rate is higher compared to that of lighter PAHs [9,12]. PAHs levels in seafood also depend on the nutritional condition of the organism [13] and on the season [14], likely as an effect of changes in the pollutant environmental inputs [12], seasonal variation of the pollutant elimination rate [15], hydrodynamic processes [16], and/or because of factors pertaining to the reproductive cycle of the species [17]. Even the age of the fish is related to PAH accumulation, with earlier stages of life being more prone to accumulating higher amounts of contaminants because of the immaturity of detoxification pathways [15]. Finally, the level of PAHs varies with the species taken into account, and this is also because of differences in the PAH-metabolizing capability [18]. Most notably, filter feeding organisms show the slowest PAHs elimination rates [14]. Accordingly, metabolic efficiency is greater in fish, intermediate in crustaceans and lowest in molluss [19].