News

Published on June 6, 2013

Ecotoxicity and uptake of polymer coated gold nanoparticles

nanotoxicologyBioconjugated gold nanoparticles (Au NPs) are a promising tool for pharmaceutical applications. However, the ecotoxicity of these types of NPs has hardly been studied. We investigated the ecotoxicity and uptake of 4-5 nm Au NPs to which two types of polymer coatings were attached. One coating was an amphiphilic polymer only and the other an amphiphilic coating to which 10 kDa polyethylene glycol chains were attached. In both 72 h algal growth inhibition tests with the alga Pseudokirchneriella subcapitata and in 24 h resazurin cytotoxicity tests with the rainbow trout gill cell line RTGill-W1, the pegylated Au NPs were found less toxic compared to the amphiphilic coated particles. No uptake or direct interaction between particles and algal cells was observed. However, uptake/adsorption in fish gill cells reached up to >10(6) particles/cell after 1 h and particles were eliminated for ≥96% after 24 h depuration. Both particle types were found within membrane enclosed vesicles in the cytoplasm of RTgill-W1 cells.

Published on May 17, 2013

OECD publishes guidance document on developing and assessing Adverse Outcome Pathways

Recently, the Organisation for Economic Co-operation and Development (OECD) published a guidance document (No 184) on developing and assessing Adverse Outcome Pathways (AOP). The AOP methodology is an approach which provides a framework to collect, organise and evaluate relevant information on chemical, biological and toxicological effect of chemicals. This approach supports the use of a mode (and/or mechanism) of action basis for understanding adverse effects of chemicals. Our research contributes to this methodology by studying gene-expression patterns in response to toxicants (e.g. Asselman et al. 2012, Vandegehuchte et al. 2010) to extrapolate effects at the molecular level to effects at the organismal level. In addition, our population and ecosystem models (e.g. De Laender et al. 2011, Viaene et al. 2013) allow to extrapolate from this organismal level to even higher levels of organisation as the population or ecosystem. Not only contributes our research to the AOP methodology, it also benefits from it as the AOP for a marine natural toxin, domoic acid, to which we also perform research, is known.

Published on May 6, 2013

LMAE at SETAC Europe

setaclogo2 thumb medium50 75The research group Environmental Toxicology will be presenting its research at the 23rd SETAC Europe Annual Meeting in Glasgow, UK from 12-16 May 2013. We will highlight our reserach in a total of four platforms, one poster corner and nine posters. To keep track of us during the conference, to download posters or to read more information, go to our dedicated SETAC webpage.

Published on May 3, 2013

LMAE at PRIMO

Our lab will be represented at the 17th PRIMO meeting (Pollutant Responses In Marine Organisms), 5th - 8th May 2013 in Faro, Portugal. More information can be found at the conference website: http://www.cima.ualg.pt/primo17/.  There will be three posters and one platform presentation.

Published on May 3, 2013

Emerging contaminants in Belgian marine waters: Single toxicant and mixture risks of pharmaceuticals

marinepollutionbulletinKnowledge on the effects of pharmaceuticals on aquatic marine ecosystems is limited. The aim of this study was therefore to establish the effect thresholds of pharmaceutical compounds occurring in the Belgian marine environment for the marine diatom Phaeodactylum tricornutum, and subsequently perform an environmental risk assessment for these substances. Additionally, a screening-level risk assessment was performed for the pharmaceutical mixtures.

No immediate risk for acute toxic effects of these compounds on P. tricornutum were apparent at the concentrations observed in the Belgian marine environment. In two Belgian coastal harbours however, a potential chronic risk was observed for the ?-blocker propranolol. No additional risks arising from the exposure to mixtures of pharmaceuticals present in the sampling area could be detected. However, as risk characterization ratios for mixtures of up to 0.5 were observed, mixture effects could emerge should more compounds be taken into account.

Published on April 26, 2013

Cloning and functional analysis of the ecdysteroid receptor complex in the opossum shrimp Neomysis integer (Leach, 1814)

aquatic toxicologyIn this paper, the non-target effects of tebufenozide were evaluated on the estuarine crustacean, the opposum shrimp Neomysis integer (Leach, 1814). Tebufenozide is a synthetic non-steroidal ecdysone agonist insecticide and regarded as potential endocrine-disrupting chemical (EDC). N. integer is the most used crustacean in ecotoxicological research in parallel to Daphnia sp. and has been proposed for the regulatory testing of potential EDCs in the US, Europe and Japan.

Major results were: (i) cDNAs encoding the ecdysteroid receptor (EcR) and the retinoid-X-receptor (RXR), were cloned and sequenced, and subsequent molecular phylogenetic analysis (maximum likelihood and neighbor-joining) revealed that the amino acid sequence of the ligand binding domain (LBD) of N. integer EcR (NiEcR) clusters as an outgroup of the Crustacea, while NiRXR-LBD clusters in the Malacostracan clade (bootstrap percentage = 75%). (ii) 3D-modeling of ligand binding to NiEcR-LBD demonstrated an incompatibility of the insecticide tebufenozide to fit into the NiEcR-ligand binding pocket. This was in great contrast to ponasterone A (PonA) that is the natural molting hormone in

Published on April 24, 2013

Modelling the effects of copper on soil organisms and processes using the free ion approach: Towards a multi-species toxicity model

env_pollutOur lab has a long history of metal bioavailability research. Here, the results of previous terrestrial studies performed by our lab was used and integrated with other datasets to develop a general biovailability model for copper. The free ion approach has been previously used to calculate critical limit concentrations for soil metals based on point estimates of toxicity. In this study, the approach was applied to dose–response data for copper effects on seven biological endpoints in each of 19 European soils. The approach was applied using the concept of an effective dose, comprising a function of the concentrations of free copper and 'protective' major cations, including H+. A significant influence of H+ on the toxicity of Cu2+ was found, while the effects of other cations were inconsistent. The model could be generalised by forcing the effect of H+ and the slope of the dose–response relationship to be equal for all endpoints. This suggests the possibility of a general bioavailability model for copper effects on organisms. Furthermore, the possibility of such a model could be explored for other cationic metals such as nickel, zinc, cadmium and lead.

Full reference (link)

Published on April 18, 2013

New techniques for the detection of microplastics in sediments and field collected organisms

marinepollutionbulletinMicroplastics have been reported in marine environments worldwide. Accurate assessment of quantity and type is therefore needed. Here, we propose new techniques for extracting microplastics from sediment and invertebrate tissue. The method developed for sediments involves a volume reduction of the sample by elutriation, followed by density separation using a high density NaI solution. Comparison of this methods' efficiency to that of a widely used technique indicated that the new method has a considerably higher extraction efficiency. For fibres and granules an increase of 23% and 39% was noted, extraction efficiency of PVC increased by 100%. The second method aimed at extracting microplastics from animal tissues based on chemical digestion. Extraction of microspheres yielded high efficiencies (94–98%). For fibres, efficiencies were highly variable (0–98%), depending on polymer type. The use of these two techniques will result in a more complete assessment of marine microplastic concentrations.

Full reference (link)

Claessens M, Van Cauwenberghe L, Vandegehuchte M, Janssen CR. 2013. New techniques for the detection

Published on April 15, 2013

Prof. Janssen elected Chair of EU Committee SCHER

eu logo enOn 11 and 12 April 2013, the first meeting of the newly appointed EU Scientific Committee SCHER took place in Luxembourg. After a rigorous selection procedure - i.e. there were more than 400 candidates - based on criteria such as scientific excellence and independence, Prof. Janssen was appointed as one of the 11 members of SCHER (Scientific Committee on Health and Environmental Risks). Committee members are appointed for a three-year term and will provide the Commission with independent scientific advice on issues relating to consumer safety, public health and the environment. Following his appointment Prof. Janssen was then elected by SCHER members to serve as Chair of the Committee.

More information on SCHER and the inaugural meeting: http://ec.europa.eu/health/scientific_committees/events/ev_20130411_en.htm#pics.

scher cj

Published on April 10, 2013

Monitoring micropollutants in marine waters, can quality standards be met?

marinepollutionbulletinThe environmental risks of 33 micropollutants occurring in Belgian coastal zone were assessed as single substances and as mixtures. Water and sediment samples were taken in harbors, coastal waters and the Scheldt estuary during 2007–2009. Measured environmental concentrations were compared to quality standards such as Predicted No Effect Concentrations (PNECs), Environmental Quality Standards (EQSs), and Ecotoxicological Assessment Criteria (EAC). Out of a total of 2547 samples analyzed, 232 and 126 samples exceeded the EQS and EAC, respectively. Highest risks were observed for TBT, PBDEs, PCBs and the PAHs anthracene, indeno(1,2,3-cd)pyrene, benzo(g,h,i)perylene, benzo(k)fluoranthene, and benzo(b)fluoranthene in the water compartment and for TBT and PCBs in the sediment compartment. Samples taken at all stations during the April 2008 campaign indicate a potential risk of the contaminant mixtures to the aquatic environment (except W06 station). This study argues the need to revise quality standards when appropriate and hence the overall regulatory implication of these standards.

Full reference (link)

Ghekiere A, Verdonck F, Claessens M, Monteyne E, Roose P, Wille K, Goffin A, Rappé K, Janssen CR. 2013. Monitoring micropollutants in marine waters, can quality

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