Coastal pollution of aquatic systems:Literature review and experiments focusing on metal fate on estuaries

PhDAnthropocene is the current era in which human activities modify various environmental properties, which have implications for many coastal processes. Anthropogenic stressors increasingly affect coasts and push these environments to a new altered equilibrium state. However, monitoring such pollution is a challenging task because coastal systems are highly dynamic and integrate the physicochemical forces at work on freshwater bodies, estuaries and lagoons with the oceanographic characteristics of adjacent seas. The current thesis addresses pollution of coastal environments in a broad way, with special attention to the current and historic problematic of estuarine contamination by metals. Firstly, it introduces the chemical (e.g. metals, persistent organic pollutants, and emerging contaminants), physical (e.g. microplastics, sediment loads, temperature), and biological (e.g. microbiological contamination, invasive species) pervasive anthropogenic influence in coastal areas. This introductory chapter is followed by a discussion on the limitations towards holistic environmental health assessments that are imposed by the scarcity of tools and multidisciplinary approaches. At that juncture, we perform a deep investigation of metal fate and its effects in estuaries. The review of the scientific literature in the third chapter provides a transdisciplinary conceptual framework for the estuarine behaviour of metals and its impacts on fauna and flora. This comprehensive overview and conceptual model are further accompanied by an elaboration on empirical models, as well as discussion of data on metal behaviour under laboratory and field conditions. While our review postulates that most studies had observed a non-conservative behaviour of metals in estuaries, our data suggests that at local scale such phenomenon is greatly explained by a high metal mobilisation driven by biogeochemical gradients. In fact, our results demonstrate that iron mobilisation regulates the pollution levels of iron and potentially other metals in an intertidal area under strong anthropogenic influence. In summary, estuarine physicochemical gradients, biogeochemical processes, and organism physiology are jointly coordinating the fate and potential effects of metals in estuaries, and both realistic model approaches and attempts to postulate site-specific water quality criteria or water/sediment standards must consider such interactions.EACEA (Education, Audiovisual and Culture Executive Agency

Potential for high toxicity of polystyrene nanoplastics to the European Daphnia longispina

Background Current regulatory discussions about microplastics are often questioned based on a lack of data indicating high ecotoxic hazards of these particles within standard and recognized definitions. Moreover, there is scientific debate on what metrics to report the micro-nanoplastics toxicity (i.e. mass or particle counts-based exposure). We present here the high potential sensitivity of three genotypically different clones of the European Daphnia longispina species complex exposed to non-functionalized polystyrene nanobeads of 50 nm and 100 nm in diameter according to adapted OECD 202 test protocol. Results EC50s 48 h varied from 0.2 to 8.9 mg L−1 (mean 2.49 mg L−1) for 50 nm beads, and from 32.7 to 90.3 mg L−1 (mean 59.39 mg L−1) for the 100 nm. EC10s 48 h varied from 0.0007 to 7.5 mg L−1 (mean 0.28 mg L−1) for 50 nm beads, and from 25.5 to 69.1 mg L−1 (mean 47.51 mg L−1) for the 100 nm. Inter-clonal variability was about tenfold. Therefore, several 1000 s-fold variations in mass-based ecotoxicity for these polystyrene beads was observed if particle size and Daphnia genotype are considered jointly. Conclusions Such ecotoxicity potential is comparable to highly toxic chemicals in global and EU-based regulatory classification and labelling. Ecotoxicity based on particle counts suggested convergence of EC50s, with effects generally observed around 1011 to1015 particles L−1. The present results highlight the potential high hazard of these particles and the relevance of particle size and exposure metrics on hazard conclusion

Circulating microRNAs in sera correlate with soluble biomarkers of immune activation but do not predict mortality in ART treated individuals with HIV-1 infection: A case control study

Introduction: The use of anti-retroviral therapy (ART) has dramatically reduced HIV-1 associated morbidity and mortality. However, HIV-1 infected individuals have increased rates of morbidity and mortality compared to the non-HIV-1 infected population and this appears to be related to end-organ diseases collectively referred to as Serious Non-AIDS Events (SNAEs). Circulating miRNAs are reported as promising biomarkers for a number of human disease conditions including those that constitute SNAEs. Our study sought to investigate the potential of selected miRNAs in predicting mortality in HIV-1 infected ART treated individuals. Materials and Methods: A set of miRNAs was chosen based on published associations with human disease conditions that constitute SNAEs. This case: control study compared 126 cases (individuals who died whilst on therapy), and 247 matched controls (individuals who remained alive). Cases and controls were ART treated participants of two pivotal HIV-1 trials. The relative abundance of each miRNA in serum was measured, by RTqPCR. Associations with mortality (all-cause, cardiovascular and malignancy) were assessed by logistic regression analysis. Correlations between miRNAs and CD4+ T cell count, hs-CRP, IL-6 and D-dimer were also assessed. Results: None of the selected miRNAs was associated with all-cause, cardiovascular or malignancy mortality. The levels of three miRNAs (miRs -21, -122 and -200a) correlated with IL-6 while miR-21 also correlated with D-dimer. Additionally, the abundance of miRs -31, -150 and -223, correlated with baseline CD4+ T cell count while the same three miRNAs plus miR- 145 correlated with nadir CD4+ T cell count. Discussion: No associations with mortality were found with any circulating miRNA studied. These results cast doubt onto the effectiveness of circulating miRNA as early predictors of mortality or the major underlying diseases that contribute to mortality in participants treated for HIV-1 infection

Erratum: Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017

Interpretation: By quantifying levels and trends in exposures to risk factors and the resulting disease burden, this assessment offers insight into where past policy and programme efforts might have been successful and highlights current priorities for public health action. Decreases in behavioural, environmental, and occupational risks have largely offset the effects of population growth and ageing, in relation to trends in absolute burden. Conversely, the combination of increasing metabolic risks and population ageing will probably continue to drive the increasing trends in non-communicable diseases at the global level, which presents both a public health challenge and opportunity. We see considerable spatiotemporal heterogeneity in levels of risk exposure and risk-attributable burden. Although levels of development underlie some of this heterogeneity, O/E ratios show risks for which countries are overperforming or underperforming relative to their level of development. As such, these ratios provide a benchmarking tool to help to focus local decision making. Our findings reinforce the importance of both risk exposure monitoring and epidemiological research to assess causal connections between risks and health outcomes, and they highlight the usefulness of the GBD study in synthesising data to draw comprehensive and robust conclusions that help to inform good policy and strategic health planning

Development and Validation of a Risk Score for Chronic Kidney Disease in HIV Infection Using Prospective Cohort Data from the D:A:D Study

Ristola M. on työryhmien DAD Study Grp ; Royal Free Hosp Clin Cohort ; INSIGHT Study Grp ; SMART Study Grp ; ESPRIT Study Grp jäsen.Background Chronic kidney disease (CKD) is a major health issue for HIV-positive individuals, associated with increased morbidity and mortality. Development and implementation of a risk score model for CKD would allow comparison of the risks and benefits of adding potentially nephrotoxic antiretrovirals to a treatment regimen and would identify those at greatest risk of CKD. The aims of this study were to develop a simple, externally validated, and widely applicable long-term risk score model for CKD in HIV-positive individuals that can guide decision making in clinical practice. Methods and Findings A total of 17,954 HIV-positive individuals from the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study with >= 3 estimated glomerular filtration rate (eGFR) values after 1 January 2004 were included. Baseline was defined as the first eGFR > 60 ml/min/1.73 m2 after 1 January 2004; individuals with exposure to tenofovir, atazanavir, atazanavir/ritonavir, lopinavir/ritonavir, other boosted protease inhibitors before baseline were excluded. CKD was defined as confirmed (>3 mo apart) eGFR In the D:A:D study, 641 individuals developed CKD during 103,185 person-years of follow-up (PYFU; incidence 6.2/1,000 PYFU, 95% CI 5.7-6.7; median follow-up 6.1 y, range 0.3-9.1 y). Older age, intravenous drug use, hepatitis C coinfection, lower baseline eGFR, female gender, lower CD4 count nadir, hypertension, diabetes, and cardiovascular disease (CVD) predicted CKD. The adjusted incidence rate ratios of these nine categorical variables were scaled and summed to create the risk score. The median risk score at baseline was -2 (interquartile range -4 to 2). There was a 1: 393 chance of developing CKD in the next 5 y in the low risk group (risk score = 5, 505 events), respectively. Number needed to harm (NNTH) at 5 y when starting unboosted atazanavir or lopinavir/ritonavir among those with a low risk score was 1,702 (95% CI 1,166-3,367); NNTH was 202 (95% CI 159-278) and 21 (95% CI 19-23), respectively, for those with a medium and high risk score. NNTH was 739 (95% CI 506-1462), 88 (95% CI 69-121), and 9 (95% CI 8-10) for those with a low, medium, and high risk score, respectively, starting tenofovir, atazanavir/ritonavir, or another boosted protease inhibitor. The Royal Free Hospital Clinic Cohort included 2,548 individuals, of whom 94 individuals developed CKD (3.7%) during 18,376 PYFU (median follow-up 7.4 y, range 0.3-12.7 y). Of 2,013 individuals included from the SMART/ESPRIT control arms, 32 individuals developed CKD (1.6%) during 8,452 PYFU (median follow-up 4.1 y, range 0.6-8.1 y). External validation showed that the risk score predicted well in these cohorts. Limitations of this study included limited data on race and no information on proteinuria. Conclusions Both traditional and HIV-related risk factors were predictive of CKD. These factors were used to develop a risk score for CKD in HIV infection, externally validated, that has direct clinical relevance for patients and clinicians to weigh the benefits of certain antiretrovirals against the risk of CKD and to identify those at greatest risk of CKD.Peer reviewe

Literaturrecherche und Experimente mit Schwerpunkt auf Metallschicksal in Ästuaren

Acknowledgements……………………………………………………………………………………………....4 Responsibility claim………………………………………………………………………………………………5 Collaboration Statement ...……………………………………………………………………………………...6 Preface…………………………………………………………………………………………………………….7 Abstract…………………………………………………………………………………………………………..13 Zusammenfassung …………………………………………………………………………………………….14 Part 1 Introduction to coastal and marine pollution…………………………………………………………16 1\. Coastal and marine pollution in the Anthropocene: Identifying contaminants and processes..17 I. Abstract..……………………………………………………………………………………..18 II. Introduction ………………………………………………………………………………….19 III. Identifying contaminants & stressors……………………………………………………...20 IV. Identifying processes ……………………………………………………………………….23 i. Global changes …………………………………………………………………....23 ii. Atmospheric circulation …………………………………………………………..25 iii. Biological processes and effects ……………………………………….………..27 V. Final remarks……………………………………………………………………….………..28 VI. Acknowledgements…………………………………………………………………………29 VII. References…………………………………………………………………………………..29 2\. Assessment of pollution and environmental restoration in coastal areas: challenges and solutions ……………………………………………………………………………………………….33 I. Abstract……………………………………………………………………………………….34 II. Introduction.………………………………………………………………………………….35 III. Environmental health assessment ………………………………………………………..36 IV. Challenges and solutions for environmental management….………………………….38 i. Contamination assessment and analysis ………………………………………38 ii. Biomarkers: a promising set of biomonitoring tools……………………………39 iii. Coastal restoration, contamination, and climate change………………………40 iv. A mitigation tool: Managed realignment ……………………………………......40 1\. Risks of managed realignment………………………………………….41 2\. Coastal restoration and management in Europe……………………...41 3\. Managed realignment and potential contamination…………………..42 v. Uncertainties ……………………………………………………………………….42 1\. Climate Change Uncertainty ……………………………………………42 2\. Political Uncertainty ……………………………………………………..43 V. Conclusions ………………………………………………………………………………….43 VI. References..………………………………………………………………………………….44 Part 2 The problematic of metal pollution in estuaries……………………………………………………..50 3\. Metal fate and effects in estuaries: A review and conceptual model for better understanding of toxicity…………………………………………………………………………………………………..51 I. Visual abstract...……………………………………………………………………………..52 II. Abstract……………………………………………………………………………………….53 III. Introduction..…………………………………………………………………………………53 IV. Scope and Terminology…………………………………………………………………….55 i. Terminology...………………………………………………………………………56 V. The conceptual model of metal fate in estuaries…………………………………………56 i. Physico-chemical estuarine features: environmental gradients and non-conservative metal behavior……………………………………………………...57 ii. Sources and emission pathways of metals to estuaries……………………….59 VI. Physical processes: metal transport in estuaries………………………………………...61 i. Changes in flow affecting metal distribution…………………………………….61 ii. Changes in flow that affect metal concentration and partitioning…………….63 iii. Sorption and desorption: the physico-chemical interactions of sorbents and salinity……………………………………………………………………………….64 iv. Sedimentation and metal removal from surface waters……………………….65 VII. Metal remobilization processes…………………………………………………………….65 i. Chemical metal remobilization……………………………………………………66 ii. Chemical and biologically mediated metal remobilization……………………..66 iii. Chemical and physically mediated metal remobilization..……………………..67 VIII. Interactions with biological processes…………………………………………………….68 i. Physical, chemical and biological interactions for metal remobilization……..68 ii. Phytoplankton affecting partitioning and advection of metals…………………70 IX. Organism physiology and effects of metals……………………………………………....72 i. Phytoplankton and environmental toxicity of metals…...................................72 ii. Metal impact on estuarine biota………………………………………………….74 iii. Physiology interfering the mechanism of metal toxicity in estuaries…………75 iv. A conceptual model for metal toxicity in estuaries……...................................76 X. Final considerations and future directions on modelling metal fate an effects on estuaries……………………………………………………………………………………...81 XI. Acknowledgements………………………………………………………………………….83 XII. References……………………………………………………….......................................83 4\. Unravelling metal mobility under complex contaminant signatures……………………………..93 I. Introduction…...……………………………………………………………………………...96 II. Material and Methods……………………………………………………………………….98 i. Terminology and definitions………………………………………………………98 ii. Study area………………………………………………………………………….99 iii. Laboratory experiments to quantify leaching potential……………………….101 iv. Field assessment…………………………………………………………………102 v. Physic-chemical parameters analysed…………………………………………102 1\. Water percentage and Loss of ignition……………………………….103 2\. Aqua Regia extraction …………………………………………………103 3\. Metal quantification……………………………………………………..104 4\. Geochemical normalization and enrichment factors………..………105 5\. Statistical methods……………………………………………………...106 vi. Results and Discussion………………………………………………………….106 1\. Potentially high metal leaching in estuarine sediments…………….107 2\. Mobilisation drives in situ metal concentration on estuarine sediments………………………………………………………………..110 3\. Sediment geochemistry and pollution levels…………………………112 4\. High metal mobility in situ on estuarine sediments………………….115 vii. Conclusions and Future Directions……………………………………………..116 viii. Acknowledgements ……………………………………………………………...117 ix. References ……………………………………………………………………….117 5\. Conclusions and future directions………………………………………………………………….121 I. General conclusions and future direction………………………………………………..122 II. References………………………………………………………………………...............124 6\. Apendices…………………………………………………………………………………………….125 I. List of articles published during the development of the thesis………………………….126 II. Supplementary Material for chapter 4.……………………………………………………..127 7\. Afterword……………………………………………………………………………………………..132 III. Frontiers on ecotoxicology…………………………………………………………………..133 i. Microorganisms as prospective microcontaminats: Potential environmental impacts of an “Underground Revolution”………………………………………134 ii. Yellow sign for a green pesticide: Non- monotonic dose responses for the toxicity of a Bacillus thuringiensis biocide to Daphnia magna……………….141 8\. About the author……………………………………………………………………………………..165Anthropocene is the current era in which human activities modify various environmental properties, which have implications for many coastal processes. Anthropogenic stressors increasingly affect coasts and push these environments to a new altered equilibrium state. However, monitoring such pollution is a challenging task because coastal systems are highly dynamic and integrate the physicochemical forces at work on freshwater bodies, estuaries and lagoons with the oceanographic characteristics of adjacent seas. The current thesis addresses pollution of coastal environments in a broad way, with special attention to the current and historic problematic of estuarine contamination by metals. Firstly, it introduces the chemical (e.g. metals, persistent organic pollutants, and emerging contaminants), physical (e.g. microplastics, sediment loads, temperature), and biological (e.g. microbiological contamination, invasive species) pervasive anthropogenic influence in coastal areas. This introductory chapter is followed by a discussion on the limitations towards holistic environmental health assessments that are imposed by the scarcity of tools and multidisciplinary approaches. At that juncture, we perform a deep investigation of metal fate and its effects in estuaries. The review of the scientific literature in the third chapter provides a transdisciplinary conceptual framework for the estuarine behaviour of metals and its impacts on fauna and flora. This comprehensive overview and conceptual model are further accompanied by an elaboration on empirical models, as well as discussion of data on metal behaviour under laboratory and field conditions. While our review postulates that most studies had observed a non- conservative behaviour of metals in estuaries, our data suggests that at local scale such phenomenon is greatly explained by a high metal mobilisation driven by biogeochemical gradients. In fact, our results demonstrate that iron mobilisation regulates the pollution levels of iron and potentially other metals in an intertidal area under strong anthropogenic influence. In summary, estuarine physicochemical gradients, biogeochemical processes, and organism physiology are jointly coordinating the fate and potential effects of metals in estuaries, and both realistic model approaches and attempts to postulate site-specific water quality criteria or water/sediment standards must consider such interactions.Das Anthropocen ist das jetzige Zeitalter, in dem menschliche Aktivitäten zu Umweltveränderungen führen, die sich auch auf viele Küstenprozesse auswirken. Anthropogene Stressoren beeinflussen zunehmend Küsten und zwingen diese Ökosysteme in einen neuen veränderten Gleichgewichtszustand. Eine Überwachung dieser Verschmutzung ist eine anspruchsvolle Aufgabe, da Küstensysteme sehr dynamisch sind und die physikalisch-chemischen Kräfte von Binnengewässern, Flussmündungen und Lagunen mit den ozeanografischen Prozessen der angrenzenden Meere verbinden. Die vorliegende Doktorarbeit befasst sich mit der Verschmutzung der Küstengebiete in einem breitgefächerten Ansatz. Sie beleuchtet hauptsächlich das noch ungelöste Problem der Ästuarverseuchung mit Metallen. Zum einen werden die chemischen (z.B. Metalle, persistente organische Schadstoffe, und “Emerging Contaminants“), physikalische (zum Beispiel Mikroplastik, Sedimentfrachten, Temperatur) und biologische (zum Beispiel mikrobiologische Kontamination, invasive Arten) anthropogenen durchdringen Einfluss in den Küstengebieten eingeführt. Diesem einleitenden Kapitel schliesst sich eine Diskussion an über die Grenzen für eine ganzheitliche Umweltgesundheitsuntersuchung, die durch den Mangel an Werkzeugen und multidisziplinäre Ansätze bedingt sind. In diesen Zusammenhang wird eine eingehende Untersuchung über das Schicksal von Metallen und ihre Auswirkungen in Ästuaren durchgeführt. Wir haben anhand der wissenschaftlichen Literatur einen transdisziplinären konzeptionellen Rahmen entwickelt für das Verhalten von Metallen in Mündungsgebieten und deren Auswirkungen auf die Fauna und Flora. Diese umfassende Übersicht und unser konzeptionelles Modell ergänzeten wir durch eine Abhandlung empirischer Modelle, sowie die Diskussion vorhandener Daten über das Verhalten von Metallen unter Labor- und Feldbedingungen. Während beispielsweise die meisten Veröffentlichungen ein nicht-konservatives Verhalten von Metallen in den Mündungen berichteten, legen unsere Daten nahe, dass ein solches Phänomen auf lokaler Skala als einer hohen Metall-Mobilisierung durch biogeochemische Gradienten erklärt werden kann. Wir konnten tatsächlich zeigen, dass die Eisen-Mobilisierung die Schadstoffbelastung reguliert von diesem und wahrscheinlich auch andere Metalle in einer stark antropogen beeinflußten Gezeitenzone. Insgesamt können wir also zeigen, dass physikalisch-chemische Gradienten, biogeochemische Prozesse und die Physiologie von Lebewesen gemeinsam das Schicksal und die möglichen Auswirkungen von Metallen in den Mündungen beeinflussen. Realistische Modellansätze und Festsetzungen ortsspezifischer Wasser-Qualität- Kriterien oder Wasser / Sediment-Standards müssen solche Interaktionen berücksichtigen

Biomarcadores de contaminação aquática em Poecilia vivipara

Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós–Graduação em Oceanografia Biológica, Instituto de Oceanografia, 2012.A poluição aquática em zonas costeiras é crescente, exigindo cada vez mais o uso de ferramentas alternativas para seu monitoramento. Dentre estas, as de maior potencial são os biomarcadores, que são medidas biológicas capazes de expressar exposição ou efeito deletério de contaminantes. Porém, a falta de informação sobre respostas de biomarcadores a contaminantes em concentrações ambientalmente relevantes constitui empecilho ao emprego destas ferramentas. Neste trabalho foram analisados os efeitos de três contaminantes em diversos biomarcadores usualmente utilizados em estudos de avaliação ambiental. Os contaminantes testados foram cobre (metal), atrazina (herbicida) e fenantreno (hidrocarboneto policíclico aromático). Os biomarcadores avaliados foram atividades enzimáticas (superóxido dismutase, catalase, glutationa redutase e glutationa s-transferase), concentração de metalotioneínas, espécies reativas de oxigênio, capacidade antioxidante, peroxidação lipídica, quebras na fita de DNA, freqüência de células micronucleadas e de anomalias nucleares, e composição iônica corporal. Os três contaminantes demonstraram potencial para afetar os biomarcadores avaliados, porém cada um afetou distintamente os grupos de biomarcadores. O efeito do cobre foi caracterizado por um elevado potencial de geração de estresse oxidativo em brânquias, fígado e músculo, além de causar dano genético através da quebra da fita de DNA e clastogenicidade. A atrazina aumentou a atividade da glutationa s-transferase, causou estresse oxidativo branquial e danos genéticos não detectáveis no ensaio cometa. Por fim, o fenantreno gerou estresse oxidativo muscular, sendo a maioria dos danos possivelmente relacionada à geração de metabólitos reativos durante sua degradação, resultando em elevada genotoxicidade e citotoxicidade, bem como perturbações de sistemas enzimáticos e da fisiologia do animal.Aquatic pollution in coastal areas is increasing, demanding the use of alternative tools for its adequate monitoring. Among them, biomarkers are those showing higher potential for practical use. They are biological measurements capable of detecting the exposure and effects of contaminants. However, the lack of information on the response of biomarkers to contaminants at environmentally relevant levels is a constraint for the employment of these tools in monitoring programs. In the present study, the effects of three contaminants on several biomarkers commonly employed in environmental analyses were evaluated. Contaminants tested were copper (metal), atrazine (herbicide) and phenanthrene (polycyclic aromatic hydrocarbon). Biomarkers evaluated were enzyme activities (superoxide dismutase, catalase, glutathione reductase and glutathione s-transferase), metallothioneins concentration, reactive oxygen species, antioxidant capacity, lipid peroxidation, DNA strand-breaks, micronucleated cells and nuclear anomalies frequencies, and whole-body ion composition. The three contaminants showed potential to affect the biomarkers evaluated. However, each contaminant affected distinctly the groups of biomarkers. Copper effect was characterized by a elevated potential for oxidative stress generation in gills, liver and muscle. It also induced genetic damage (DNA strand-breaks) and clastogenicity. Atrazine increased glutathione stransferase activity, caused oxidative stress in gills and genetic damage non detectable by the Comet assay. Finally, phenanthrene induced oxidative stress in muscle, being most of the damage likely associated with the generation of reactive metabolites during the contaminant degradation process. Exposure to phenanthrene resulted in elevated genotoxicity and cytotoxicity, as well as perturbations of the enzymatic systems and the whole-animal physiology

Potential for high toxicity of polystyrene nanoplastics to the European Daphnia longispina

Abstract Background Current regulatory discussions about microplastics are often questioned based on a lack of data indicating high ecotoxic hazards of these particles within standard and recognized definitions. Moreover, there is scientific debate on what metrics to report the micro-nanoplastics toxicity (i.e. mass or particle counts-based exposure). We present here the high potential sensitivity of three genotypically different clones of the European Daphnia longispina species complex exposed to non-functionalized polystyrene nanobeads of 50 nm and 100 nm in diameter according to adapted OECD 202 test protocol. Results EC50s 48 h varied from 0.2 to 8.9 mg L−1 (mean 2.49 mg L−1) for 50 nm beads, and from 32.7 to 90.3 mg L−1 (mean 59.39 mg L−1) for the 100 nm. EC10s 48 h varied from 0.0007 to 7.5 mg L−1 (mean 0.28 mg L−1) for 50 nm beads, and from 25.5 to 69.1 mg L−1 (mean 47.51 mg L−1) for the 100 nm. Inter-clonal variability was about tenfold. Therefore, several 1000 s-fold variations in mass-based ecotoxicity for these polystyrene beads was observed if particle size and Daphnia genotype are considered jointly. Conclusions Such ecotoxicity potential is comparable to highly toxic chemicals in global and EU-based regulatory classification and labelling. Ecotoxicity based on particle counts suggested convergence of EC50s, with effects generally observed around 1011 to1015 particles L−1. The present results highlight the potential high hazard of these particles and the relevance of particle size and exposure metrics on hazard conclusion. Graphical Abstrac