Bioconcentration and depuration of organic pollutants in European eels and the influence of microplastics: A laboratory approach

High levels of organic pollutants (OPs) have been found in the habitats of European eels, however little is known about their bioconcentration/bioaccumulation and depuration kinetics in different tissues. In this research, such kinetics of a mixture of 22 OPs in muscle, liver tissue and plasma of silver European eel were studied through a laboratory approach, including 10 pharmaceuticals and personal care products (PPCPs), 5 pesticides, 5 perfluoroalkyl substances (PFAS) and 2 illicit drugs. Eels were distributed in three groups: control, exposed to OPs, and exposed to OPs and polyethylene microplastics (MPs), during 58 days in two phases: exposure (days 0-28) and depuration (days 29-58). Muscle, liver and plasma samples were analysed via UHPLC-MS/MS. OPs showed increasing concentrations in the three tissues for several compounds (e.g. PFAS, chlorpyrifos, and terbuthylazine). PFAS bioconcentration followed the trend plasma > liver tissue > muscle. Two tendencies were also observed in the depuration phase. One with OPs concentrations that tended to decrease (chlorpyrifos and terbuthylazine), another one, with concentration values that were similar or even tended to be higher than at the exposure phase (PFDA, PFOS, and PFOA). The presence of MPs seemed to affect the bioconcentration and depuration of OPs in eel tissues with increased (e.g. PFAS in liver and plasma) or decreased (e.g. PFAS and chlorpyrifos in muscle) bioconcentration. Pollutants are believed to be a key issue in understanding the reasons for the eels’ stock decrease and therefore, further research about PFAS, PPCPs and pesticides accumulation, depuration and toxicity on this "critically endangered" species is imperative. • Bioconcentration and depuration of OPs were assessed in muscle, liver and plasma of European eels. • Toxico-kinetic modelling revealed different bioconcentration and depuration trends between OPs and between tissues. • PFDA, PFOS, and PFOA were increasingly accumulated in both exposure and depuration phases. • Chlorpyrifos and terbuthylazine were bioconcentrated and depurated from all matrices. • Increased kinetic bioconcentration factors of OPs in eel tissues due to MPs presence.