Dioxin-like, non-dioxin like PCB and PCDD/F contamination in European eel (Anguilla anguilla) from the Loire estuarine continuum: spatial and biological variabilities

To characterize the eel contamination by dioxin-like (dl) and non dioxin-like (ndl) PCBs and PCDD/Fs, 62 eels from the Loire estuary (France) were analyzed. PCB contamination significantly increased from glass eel stage (3.7 ±1.9 and 15.2±4.2 ng.g-1 dw) to other life stages (for yellow eels: 62.8±34.4 and 381.8±181.8 ng.g-1 dw; for silver eels: 93.7±56.3 and 463.2±244.6 ng.g-1 dw respectively for dl and ndl PCB). An inter-site variability based on PCB levels and fingerprints was observed between the three studied sites. The glass eel pattern was mainly characterized by the less chlorinated PCBs contrarily to the other eels, underlying a different bioaccumulation pathway. Overall, eels from this estuary showed an intermediate contamination level compared to other international/national areas. However, more than 60% of studied silver eels displayed WHO2005 PCDD/F and dl-PCB TEQ values higher than the recommended level of 10 pg.g-1 ww. This statement indicates a potential exposure to PCBs through eel consumption, especially with silver individuals, and could potentially lead to damages for the eel population

Ecotoxicity of lanthanides to Daphnia magna: insights from elemental behavior and speciation in a standardized test medium

Lanthanides (LNs) are a group of 15 elements with steadily increasing economical importance due to their multiple uses in technologies essential for sustainable ecological, digital and energetic transitions. Although knowledge on LN ecotoxicology has greatly improved over the last decade, uncertainty persists with regard to their actual hazard and risk in freshwater environments. In particular, only limited information is available on i) the actual relationships between LN speciation vs. ecotoxicological responses in standardized laboratory tests and ii) the existence of regular and predictable patterns in LN ecotoxicity (expressed as e.g., EC50) along the LN series. The present paper provides the first report on the ecotoxicity of all lanthanides (except Pm) for the freshwater crustacean Daphnia magna along with an unprecedented level of detail on LN speciation in the exposure medium.Experimental data show that exposure concentrations can decrease by up to 95 % over the test duration, with the percentage decrease being inversely related with LN atomic mass. Thermodynamic speciation calculations confirm the possible formation of insoluble species, mainly LN carbonates. However, the corresponding theoretical solubility limits do not fully agree with measured concentrations at the end of the tests. Experimental verification of exposure concentrations (as a minimum at the beginning and end of laboratory tests) remains therefore mandatory to reach proper conclusions as to the ecotoxicity of each LN. A decreasing trend in ecotoxicity can actually be observed along the LN series when temporal changes in the exposure concentrations are properly accounted for. However, this trend remains dependent on exposure time and selected exposure metrics. This and other caveats must be considered in future research to reach a community-based consensus for the proper hazard and risk assessment of LN towards daphnids and other aquatic organisms

Ecotoxicity of lanthanides to Daphnia magna: insights from elemental behavior and speciation in a standardized test medium

Lanthanides (LNs) are a group of 15 elements with steadily increasing economical importance due to their multiple uses in technologies essential for sustainable ecological, digital and energetic transitions. Although knowledge on LN ecotoxicology has greatly improved over the last decade, uncertainty persists with regard to their actual hazard and risk in freshwater environments. In particular, only limited information is available on i) the actual relationships between LN speciation vs. ecotoxicological responses in standardized laboratory tests and ii) the existence of regular and predictable patterns in LN ecotoxicity (expressed as e.g., EC50) along the LN series. The present paper provides the first report on the ecotoxicity of all lanthanides (except Pm) for the freshwater crustacean Daphnia magna along with an unprecedented level of detail on LN speciation in the exposure medium.Experimental data show that exposure concentrations can decrease by up to 95 % over the test duration, with the percentage decrease being inversely related with LN atomic mass. Thermodynamic speciation calculations confirm the possible formation of insoluble species, mainly LN carbonates. However, the corresponding theoretical solubility limits do not fully agree with measured concentrations at the end of the tests. Experimental verification of exposure concentrations (as a minimum at the beginning and end of laboratory tests) remains therefore mandatory to reach proper conclusions as to the ecotoxicity of each LN. A decreasing trend in ecotoxicity can actually be observed along the LN series when temporal changes in the exposure concentrations are properly accounted for. However, this trend remains dependent on exposure time and selected exposure metrics. This and other caveats must be considered in future research to reach a community-based consensus for the proper hazard and risk assessment of LN towards daphnids and other aquatic organisms

Levels and distributions of organic pollutants in subtidal sediments from the Loire estuary: Are there any relationships with TTR-binding activity?

The Loire estuary runs through important urban sites with shipping, industrial and agricultural activities, being the receptacle of diffusive pollutants comprising, a mixture of contaminants such as persistent organic pollutants (POPs). This work was set out to evaluate the occurrence of thyroid endocrine disruptors in sediments of this estuary. Sediments were collected in September 2012 and April 2013, in subtidal zones along the estuary. Targeted chemical analyses of five classes of pollutants, i.e. polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), and bisphenol A (BPA) were performed in sediment extracts. Extracts were further tested for their thyroid hormone (TH) disrupting potency to compete with TH for binding to its transporter protein transthyretin (TTR). The Haute-Indre site was characterized by a significant PAH contamination whereas Saint-Nazaire, Bellevue and Rezé would be particularly contaminated by PCBs. These observations could be linked to the different type of anthropogenic activities taking place close to these sites. Donges, Mindin and Paimboeuf were the sampling sites displaying the lowest contamination in PAHs, APs, PCBs and PBDEs. No inter-site difference could be observed for TTR-binding activity, which should be attributed to different compounds than the chemically analyzed compounds, as confirmed by PCA analyses. Furthermore, the TTR-binding potencies of the extracts were relatively low compared to data from literature. More investigations on the quantification of PCB and PBDE hydroxylated metabolites and other known endocrine disruptors such as pesticides or perfluorinated compounds could be considered, as well as bioassays highlighting other endocrine disrupting effects