1,073 research outputs found
Tox-Box: securing drops of life - an enhanced health-related approach for risk assessment of drinking water in Germany Tox-Box: Die Tropfen des Lebens bewahren - Gesundheitsbasierte Risikobewertung für Trinkwasser in Deutschland
No full textThis article introduces ‘Tox-Box’, a joint research project designed to develop a holistic approach towards a
harmonized testing strategy for exposure- and hazard-based risk management of anthropogenic trace substances in
drinking water to secure a long-term drinking water supply. The main task of the Tox-Box consortium is to enhance
the existing health-related indicator value concept (German: GOW-Konzept - Gesundheitlicher Orientierungswert)
through development and prioritization of additional end point-related testing strategies for genotoxicity,
neurotoxicity, germ cell damage, and endocrine effects. In this context, substance-specific modes of action will be
identified and characterized. Toxicological data collected by the 12 Tox-Box subprojects will be evaluated and
weighted to structure a hierarchical testing strategy for an improved risk assessment. A technical guidance
document for exposure and hazard-based risk management of anthropogenic trace substances in drinking water
will eventually be prepared
Transcriptomic and proteomic fingerprints induced by the fungicides difenoconazole and metalaxyl in zebrafish embryos
No full textIn this study, we applied OMICs analysis to identify substance-specific biomarker candidates, which may act as early indicators for specific ecotoxic modes of actions (MoA). Zebrafish embryos were exposed to two sublethal concentrations of difenoconazole and metalaxyl according to a modified protocol of the OECD test guideline No. 236. At the end of exposure, total RNA and protein were extracted, followed by transcriptomics and proteomics analysis. The analysis of significantly differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) revealed a positive exposure-response correlation in all test concentrations for both fungicides. Similarly, also a positive correlation between the obtained transcriptome and proteome data was observed, highlighting the robustness of our approach. From the detected DEGs, candidate biomarkers specific for difenoconazole (apoa1b, gatm, mylpfb and acta1b) and metalaxyl (lgals2b, abat, fabp1b.1 and myh9a) were selected, and their biological functions were discussed to assess the predictive potential.10
Assessment of the 2021 summer flood in Central Europe
No full textAbstract
The flood event in July 2021 in the uplands of the Eifel-Ardennes mountains in Germany, Belgium and The Netherlands and their foreland was caused by heavy rainfall and resulted in one of the largest flood disasters in Western Europe for decades. Due to climate change, it can be assumed that such events will become more frequent in future. Even though such extreme flood can happen at any time, the consequences and impacts can be significantly reduced by appropriate technical and non-technical measures. However, such measures always require a comprehensive understanding and knowledge of previous events and comparable processes. Therefore, this special issue aims at collecting the scientific evaluation and its implications of the 2021 extreme summer flood. This editorial serves as an introduction for an article collection published in the journal
Environmental Sciences Europe
, providing an overview of the current state of integrative assessment of the 2021 summer flood in Central Europe.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/50110000234
Toxicogenomic profiling after sublethal exposure to nerve- and muscle-targeting insecticides reveals cardiac and neuronal developmental effects in zebrafish embryos
No full textIdentification of molecular signatures for azole fungicide toxicity in zebrafish embryos by integrating transcriptomics and gene network analysis
No full textAzoles control fungal growth by inhibiting sterol biosynthesis in fungi according to the fungicide resistance action committee. Furthermore, previous studies have highlighted several effects of azole fungicides in fish including endocrine disruption. In this study, we analysed the transcriptome responses of zebrafish embryos exposed to azole fungicides to identify gene expression fingerprints indicating toxic effects such as endocrine disruption induced by sterol biosynthesis inhibition. Firstly, a modified zebrafish embryo toxicity test was conducted following the OECD 236 guideline, exposing embryos to difenoconazole, epoxiconazole, and tebuconazole. After 96 h, RNA was extracted for transcriptome analysis, which revealed concentration-dependent responses for each fungicide. Additionally, overrepresentation analysis of significantly differentially expressed genes revealed biological functions related to sterol biosynthesis and endocrine disruption. A gene set with specific expression patterns was was identified as molecular signature for indicating adverse effects induced by sterol biosynthesis inhibitors in zebrafish embryos. After further validation, the gene expression fingerprints and biomarkers identified in this study may be used in the future to identify endocrine activity of substances under development in a pre-regulatory screening using the zebrafish embryo model.37
Development of ecotoxicity testing in the standard organism Folsomia candida (Collembola)
No full textChemical analyses of the environment can document contamination by various xenobiotics but it is also important to understand the effect of pollutants on living organisms. Thus, in the present work the author investigated the effect of chemicals (imidacloprid and silver nanoparticles) at the molecular and cellular biological organization levels of a standard test organism, Folsomia candida (Collembola).In the study with the insecticide imidacloprid, the effect of the chemical was focused on the detoxifying enzyme glutathione S-transferase (GST) from F. candida. Test animals were treated with different concentrations of imidacloprid for 48 hours. Changes in steady state levels of GST mRNA and GST enzyme activity were investigated. Furthermore, enzyme extracts were separated according to their sizes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the resolved protein bands were detected by silver staining. Additionally, the size of the glutathione (GSH) pool in Collembola was also determined. Moreover, a predicted protein sequence of putative GSTs was identified with animals from the control group.A 3 fold up-regulation of GST steady state mRNA levels was detected in the samples treated with 5.0 mg L-1 imidacloprid compared to the control, while a 2.5 and a 2 fold up-regulation was found in organisms treated with 2.5 and 7.5 mg L-1 imidacloprid, respectively. GST activity increased with increasing imidacloprid amounts from an initial activity of 0.11 μmol min-1 mg-1 protein in the control group up to 0.25 μmol min-1 mg-1 protein in the sample treated with the 5.0 mg L-1 of pesticide. In contrast, the total amount of GSH decreased with increasing imidacloprid concentration.The results suggest that the alteration of the steady state level of GST mRNA, GST activity as well as GSH level may be involved in the response of F. candida upon the exposure to imidacloprid and can be used as biomarkers to monitor the toxic effects of imidacloprid and other environmental pollutants on Collembola.In case of the study with silver nanoparticles (AgNPs), chemical effects were studied (in comparison to silver nitrate) focusing on molecular and cellular alterations as ecotoxicological endpoints. At the molecular level, an up-regulation of metallothionein-containing protein (MTC) mRNA in AgNPs treated groups indicated toxic heavy metal stress effects caused by the release of silver ions from AgNPs, which was similar to animal groups treated with silver nitrate. Alteration of the steady state level of GST mRNA was also detected in animals treated with AgNPs and AgNO3. At the cellular level, the relation between GST activity and the size of the GSH pool was examined and it was found that the change of GST activity from different animal groups was not significant, whereas the GSH pool (reduced and oxidized forms) decreased with increasing concentration of AgNPs.In order to obtain direct evidence whether AgNPs causes oxidative stress, treated animals were incubated with non-fluorescent probe, 2’, 7’-dichlorodihydrofluorescein diacetate (DCFH-DA). A fluorescence signal was observed in both the AgNPs- and AgNO3 treated groups pointing to the production of reactive oxygen species (RS). Since ROS formation in F. candida is difficult to quantify, yeast strain BY4742 and mutants lacking oxidative-stress related protective enzymes were exploited as a further eukaryote model organism. As results, AgNPs and AgNO3 were found to also affect growth of yeast and induced oxidative stress.The effect of AgNPs on Collembola and yeast strains was similar to the one from AgNO3. However, AgNPs is less toxic due to the slow release of silver ions. In summary, the toxic effect of AgNPs on F. candida is caused by a combination of the release of silver ions from the AgNPs and formation of reactive species
A hierarchical testing strategy for micropollutants in drinking water regarding their potential endocrine-disrupting effects : towards health-related indicator values
No full textCombined effects of polystyrene microplastics and thermal stress on the freshwater mussel Dreissena polymorpha
No full textHuman-induced changes in the environment have increased the number of stressors impacting aquatic organism. In the light of climate change and plastic pollution, thermal stress and microplastics (MP) have become two of the most intensively studied stressors in aquatic ecosystems. Previous studies, however, mostly evaluated the impacts of thermal and MP stress in isolation, thereby neglecting joint effects.
To examine the combined effects of both, we exposed the freshwater mussel Dreissena polymorpha to irregular polystyrene MP (6.4, 160, 4000, 100,000 p mL−1) at either 14, 23 or 27 °C for 14 days and analyzed mortality, mussel activity and clearance rate, energy reserves, oxidative stress and the immunological state. Further, we exposed the mussels to diatomite (natural particle equivalent, 100,000 p mL−1) at each of the three water temperatures to compare MP and natural particle toxicity.
An increase in water temperature has a pronounced effect on D. polymorpha and significantly affects the activity, energy reserves, oxidative stress and immune function. In contrast, the effects by MP are limited to a change in the antioxidative capacity without any interactive effects between MP and thermal exposure. The comparison of the MP with a diatomite exposure revealed only limited influence of the particle type on the response of D. polymorpha to high concentrations of suspended particles.
The results indicate that MPs have minor effects on a freshwater mussel compared to thermal stress, neither alone nor as interactive effect. Limited MP toxicity could be based on adaptation mechanism of dreissenids to suspended solids. Nonetheless, MP may contribute to environmental impacts of multiple anthropogenic stressors, especially if their levels increase in the future. Therefore, we suggest integrating MP into the broader context of multiple stressor studies to understand and assess their joint impacts on freshwater ecosystems
Ecotoxicological assessment of the wastewater treatment plant Aachen-Soers and the receiving stream before and after implementation of a large-scale ozonation plant
No full textAround two-thirds of the world is covered by water; only 2.5 % is classified as freshwater, of which the majority is locked in glaciers and ice caps. Furthermore, half of the freely accessible water is already being used by mankind. This aquatic environment does not only play an important role as habitats for different aquatic species, it also provides ecosystem functions important for humans and as a resource for drinking water. Thus, the protection of the aquatic environment is of high importance. Yet, the pressure on this environment is increasing. The growing human population and increasing industrial development leads to higher disposal of anthropogenic chemicals and waste into the environment. Therefore, the European Water Framework Directive (EU-WFD) was set into operation in 2000. Its main goal is to achieve a “good biological” and a “good chemical” status of all surface waters until 2027. Among other things, this should be achieved by reducing the number of hazardous compounds introduced into the aquatic environment. For this purpose, 45 priority substances were selected that gradually should be reduced in surface waters below their so-called environmental quality standards (EQS). To support the future inclusion of new compounds into the list of priority substances, the EU watch list was published; it included ten substances or substance classes. One class consists of estrogenic compounds, including the natural estrogen 17β-estradiol as well as the synthetic compound 17α-ethinylestradiol. While these micropollutants (MPs) occur often at very low concentrations (pg · L-1 and ng · L-1 range), they are also designed to exert their biological effect at these low concentrations. However, standard chemical analytical methods are often not sensitive enough to detect them at concentrations around their EQS values. Furthermore, chemical analytical methods are not able to detect mixture effects of substances. Recent studies have shown that effect-based methods (EBMs) can detect effects at lower concentrations. Hence, they might be suitable to monitor the effects of the previously mentioned MPs. To implement EBM into the revised version of the EU-WFD as a supporting tool for chemical analysis has already been proposed. It could be shown that wastewater treatment plants (WWTPs) are one major point source of MPs into the aquatic environment, since most conventional treatment processes often fail to sufficiently reduce MPs (like benzotriazole, diclofenac, or carbamazepine). The present thesis was part of the interdisciplinary project DemO3AC. The main goal of this project was to improve the quality of the released water by the WWTP Aachen-Soers. Its recipient is the Wurm River that has shown a dissatisfying or poor biological and chemical status in the EU-WFD screenings. Downstream of the WWTP Aachen-Soers the Wurm River consists of at least 70 % of treated wastewater. As a measure to improve the quality of the Wurm River a large-scale ozonation plant was built. The present thesis aimed to ecotoxicologically assess the impact of the large-scale ozonation plant by analyzing its cleaning efficiency before (phase 1) and after (phase 2) ozonation. As a result of the treatment with ozone, an improvement of the water quality downstream of the WWTP Aachen-Soers was expected. The testing strategy was mainly based on the extended triad approach by Chapman and Hollert (2006) covering different lines of evidence (LOE; in vitro and in vivo EBMs, in situ experiments, residue analysis). The chosen EBMs were previously applied within the SOLUTIONS and NORMAN project. The in vivo methods employed belong to the classical bioassay battery (algae, daphnids, fish, luminescent bacteria) that is proposed for the assessment of wastewater by German authorities. It could be shown, that the influent of the WWTP Aachen-Soers included significant effects in the mentioned assays. Yet, the toxic potential was already reduced/eliminated by the conventional treatment processes during the first project phase. However, it has to be considered that only apical endpoints can be detected by these bioassays; mechanism-based assays may still detect effects at lower levels of biological organization. For this reason, a bigger focus was set on endocrine disrupting compounds (EDCs). These substances are continuously being released into the environment by WWTP effluents since they are not fully eliminated by conventional treatment methods. EDCs can lead to adverse effects at very low concentrations by interacting with receptors, such as the estrogenic (ER) or androgenic (AR) receptor. However, ozonation for example has shown the potential to reduce or even eliminate these effects. To investigate those effects, a bioassay battery assessing different levels of biological organization (from cell to organism) was chosen. To detect receptor-mediated agonistic (estrogenic and androgenic) as well as antagonistic (anti-estrogenic and anti-androgenic) potentials, a panel of CALUX (Chemical Activated Luciferase Expression) assays was conducted. An endocrine potential was detected before and after ozonation at all sampling points of the WWTP. Androgenicity and anti-estrogenicity seemed not to play such an important role in the aquatic environment as estrogenic or anti-androgenic compounds. The estrogenic potential was already reduced by conventional treatment and was further diminished by ozonation, yet, not fully eliminated. Nonetheless, the estrogenic potential was always reduced downstream of the WWTP in comparison to upstream, which indicates a pre-contamination of the Wurm River. Anti-androgenicity showed an increased reduction with higher ozone concentration (> 4 mg · L-1). However, for both endpoints determined equivalent concentrations were higher than the proposed effect-based trigger values indicating a potential risk for wildlife and humans. Additional measurements of single compounds (benzotriazole, bisphenol A, citalopram) showed that mixture effects (additive, antagonistic, synergistic) play a crucial role in the assessment of receptor-related endpoints. The endocrine activity was further assessed by the reproduction assay with Potamopyrgus antipodarum in the field. Results before and after ozonation did not show any effect of the ozonation on reproduction downstream of the WWTP Aachen-Soers after a four-week exposure period. In both cases, the reproduction downstream of the WWTP was significantly increased compared to the sampling sites upstream of the WWTP and the laboratory control. Since this assay was not conducted under control laboratory conditions abiotic factors could also have influenced the results of the experiments. As for the ERα CALUX assay, a pre-contamination was detected upstream of the WWTP at a higher temperature. This temperature was comparable with the temperature downstream of the WWTP for all experiments. Thus, multiple stressors (chemical load, temperature, nutrition) may have led to the increased reproduction downstream of the WWTP Aachen-Soers. Contrary to the ERα CALUX assay, no reduction of the effect was detected downstream of the WWTP Aachen-Soers. Additionally, juvenile rainbow trout (Oncorhynchus mykiss) were exposed for ten days at the Wurm River to assess the impact of the WWTP on different endpoints (body indices, vitellogenin, ethoxyresorufin-O-deethylase activity, glutathione-S-transferase activity, micronuclei, gene expression). For all endpoints assessing different potentials, no significant effect of the released wastewater before and after ozonation was detected, as well as neither a positive nor a negative influence of the installed ozonation plant. Depending on their bioaccumulation potential, some compounds need a longer period to induce adverse effects. Thus, a longer exposure period might result in a more realistic scenario for fish and potential delayed effects could be better determined. This was already shown by other studies. The impact of the WWTP Aachen-Soers was further assessed by the acute feeding assay and by determination of the internal concentration of hazardous compounds in Gammarus pulex. No clear effects in the acute feeding assay were found, likely due to the chemical load of the acute toxic compounds being too low to exert biological effects. The determination of the internal chemical load showed potential chronic effects on Gammarus pulex based on the measured toxic units. However, this effect was detected on all sample sites, and the highest influence was observed downstream of the rain overflow basin and not downstream of the WWTP Aachen-Soers. To conclude, the present thesis elucidated, that the upscaling of the WWTP Aachen-Soers with a large-scale ozonation plant resulted in a reduction of the endocrine potential and chemical load that is released into the Wurm River. Additionally, it was demonstrated that bioassays with different endpoints investigated with different levels of organization (cell and organism), under different conditions (field and laboratory), and with different sample matrices (native water sample and extract) play a crucial role in the assessment of complex environmental samples as surface and wastewaters. They can support chemical analytical methods, without knowledge of the exact sample composition. Yet, chemical analysis is still an important tool in the assessment of complex mixtures. Moreover, not only in vitro test systems should be used, since the complexity of an organism cannot be depicted by cell-based assessment alone. The present thesis was able to show, that different exposure patterns (reduction vs. no impact) were detected by different testing strategies (CALUX vs. reproduction assay). This indicates that abiotic factors can significantly impact the outcome of experiments. Finally, based on the findings of the DemO3AC project the need for implementation of further bioanalytical testing strategies into the assessment of chemicals is even more strengthened. The EU-WFD stated to support further implementation of EBMs into regulation. Other projects also set a basis for further use of those methods (SOLUTIONS, NORMAN). However, more assessment criteria need to be defined. A good start is given by other scientists. Yet, those criteria need to be consistent and find their way into regulation. The present thesis demonstrated that it is possible to make an integrative analysis of complex environmental samples (surface and wastewater) based on an assessment strategy covering different LOE (e.g., EBMs, in situ experiments, chemical analysis)
Effekt-orientierte Analytik von Flusssedimenten mit Entwicklung einer mehrstufigen automatisierten HPLC-Fraktionierungsmethode
No full textSediments can act as a sink and reservoir for compounds directly released into or generated in the environment. Sediment extracts often cause adverse effects in bioassays that can mostly not or to a minor extend be explained by target compounds and priority substances. Thus, unknowns or known compounds with unknown toxicological potential must be the cause of these effects. In order to identify these compounds, effect-directed analysis (EDA) combines biological and chemical analysis with fractionation procedures used to decrease the number of components contained in the investigated samples. In the first step of the presented work an online fractionation procedure using three coupled and automatically switched normal phase (NP)-HPLC columns was developed, allowing a class separation of compounds on the basis of different physico-chemical properties and thus a first characterisation of compounds. The method was proven to reliably fractionate sediment extracts into (1) 12 nonpolar and (2) 6 medium polar to polar fractions containing (1) halogenated aromatic hydrocarbons such as polychlorinated biphenyls (PCBs), naphthalenes (PCNs) and dibenzo-p-dioxins and -furans, separated mainly by planarity, parent and alkylated polycyclic aromatic hydrocarbons (PAHs) and nonpolar heterocyclic aromatic compounds (PACs) and related substances, separated mainly by the size of the aromatic system as well as (2) PACs with at least one polar functional group, separated primarily according to their polarity. Subsequently, six sediment samples from four highly polluted sampling sites within the Elbe and Danube River basins were fractionated using the developed procedure. Resulting fractions were investigated for mutagenic, tumor promoting (induction of the aryl hydro-carbon receptor (AhR), disruption of gap junctional intercellular communication (GJIC)), endocrine disrupting (induction of changes in thyroid hormone metabolism, estrogen receptor-mediated activites) and cytotoxic effects. Mutagenic fractions were again fractionated to further decrease the number of suspective compounds using additional reversed phase (RP)- and NP-HPLC methods. Active fractions were chemically analysed using GC-MS, LC-MS/MS and HPLC-UV DAD methods. Additionally, the procedure was applied in 10 other EDA studies for the fractionation of extracts of soil, sediment and suspended particulate matter originating from sampling sites with different pollution patterns and degrees. Biological endpoints of these studies included mutagenicity, AhR receptor-mediated activity, teratogenicity, endocrine disruption and algal toxicity. Results of all studies revealed that nonpolar fractions containing PAHs and related compounds as well as polar fractions contributed to effects observed in the bioassays. Fractions containing PCBs, PCNs and PCDD/Fs played a major role only at sites with known point sources. Although contamination patterns differed between sampling sites, rather similar toxicity patterns were determined for each biological endpoint. However, some samples showed additional single fractions with outstanding activity. A number of non priority compounds and compound groups was identified in the presented work to cause significant adverse effects in the applied biotests: dinitropyrenes, 3-nitrobenzanthrone as well as parent and cyclopentafused PAHs were confirmed to contribute mainly to mutagenicity. Confirmed AhR-agonists were parent and methylated PAHs and 7H-benz[de]anthracene-7-one. Major estrogenic active compounds included 17beta-estradiol, estrone, 17alpha-ethinylestradiol, nonylphenols, bisphenol A and 7H-benz[de]anthracene-7-one. In the other studies using the automated fractionation procedure among others thiophenes, musk compounds, furans, N-phenyl-2-naphthylamine and triclo-san contributed to observed effects. Additionally, a number of suspect compounds and compound groups was identifed, whose effects are not sufficiently evaluated so far, including heterocyclic PACs containing nitrogen, sulphur and oxygen in the aromatic system, and keto- and hydroxy-PAHs. While for some of the fractions up to 100% and more of the observed effects could have been related to identified less investigated or thoroughly evaluated toxicants, a major part of effects remained unexplained. Particularly the heterogeneous medium polar and polar fractions that played a major role for overall toxicity still contained a multitude of substances after the first fractionation step and thus suggest further fractionation. Based on the knowledge gained so far the fractionation procedure could be used as a standardised starting point for effect-directed analysis of sediment extracts allowing a first characterisation of compounds of interest. Anyhow, for identification of unknown toxi-cants the application of additional methods is necessary including chemical and biological procedures as well as computer assisted modelling techniques
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