Persistent organic pollutants in farmed sea bass (Dicentrarchus labrax L.) in two different rearing systems in the Mediterranean Sea

Persistent organic pollutants (POPs) are ubiquitous toxic compounds, highly persistent and bioaccumulative. Due to their chemical properties, POPs pose a risk of causing adverse effects to human health and environment. In this study we measured the concentration levels of polychlorobiphenyls (PCBs), perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) in the edible part of farmed sea bass reared in two different farms (site 1 and site 2) in Liguria, a region situated in northern Italy. The analytical method was based on isotope dilution with 13C labeled internal standards, followed by instrumental analysis using high-resolution gas chromatography coupled with high-resolution mass spectrometry (HRGC-HRMS) for the determination of PCBs, and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of PFOS and PFOA. We analyzed 47 samples with the aim of establishing the contamination level and human exposure to these pollutants through fish consumption. Concentration levels (mean ± standard deviation) of DL-PCBs were 0.39 ± 0.41 and 0.45 ± 0.40 pg ΣTEQ-PCB /g (f.w.) in site 1 and 2, respectively, whereas concentrations of the six indicators of NDL-PCBs were 8.66 ± 21.4 and 10.7 ± 8.27 ng Σ6 PCB /g (f.w.) in site 1 and 2, respectively. The concentration levels found in the farm located in site 1 were generally lower than those detected in the samples from site 2. Moreover, principal component analysis (PCA) showed differences also in the congeners profile between the two sites, since higher-chlorinated PCBs were more abundant in site 1 whereas lower-chlorinated PCBs were more abundant in site 2. Concerning PFOS and PFOA, most of the measured concentrations, especially of PFOA, were below the limit of detection (LOD = 0.05 ng/g f.w.). In particular, more than 90% of the samples analyzed showed levels of PFOS and PFOA lower than LOD value, and 10% showed levels in the range of low ppb. A possible reason of these low levels, could be that these pollutants do not accumulate in lipids but mainly in liver and blood. Exposure assessment using these data showed that farmed fish consumption may contribute significantly to PCBs assumption through diet, whereas for PFOS and PFOA such contribution seems to be low.