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  • 1
    Language: English
    In: 2012, Vol.7(11), p.e48956
    Description: The nanoparticle industry is expected to become a trillion dollar business in the near future. Therefore, the unintentional introduction of nanoparticles into the environment is increasingly likely. However, currently applied risk-assessment practices require further adaptation to accommodate the intrinsic nature of engineered nanoparticles. Combining a chronic flow-through exposure system with subsequent acute toxicity tests for the standard test organism Daphnia magna , we found that juvenile offspring of adults that were previously exposed to titanium dioxide nanoparticles exhibit a significantly increased sensitivity to titanium dioxide nanoparticles compared with the offspring of unexposed adults, as displayed by lower 96 h-EC 50 values. This observation is particularly remarkable because adults exhibited no differences among treatments in terms of typically assessed endpoints, such as sensitivity, number of offspring, or energy reserves. Hence, the present study suggests that ecotoxicological research requires further development to include the assessment of the environmental risks of nanoparticles for the next and hence not directly exposed generation, which is currently not included in standard test protocols.
    Keywords: Research Article ; Agriculture ; Biology ; Materials Science ; Biotechnology ; Neuroscience
    E-ISSN: 1932-6203
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  • 2
    Language: English
    In: PLoS ONE, May 1, 2015, Vol.10(5)
    Description: During their aquatic life cycle, nanoparticles are subject to environmentally driven surface modifications (e.g. agglomeration or coating) associated with aging. Although the ecotoxicological potential of nanoparticles might be affected by these processes, only limited information about the potential impact of aging is available. In this context, the present study investigated acute (96 h) and chronic (21 d) implications of systematically aged titanium dioxide nanoparticles (nTiO.sub.2 ; ~90 nm) on the standard test species Daphnia magna by following the respective test guidelines. The nTiO.sub.2 were aged for 0, 1, 3 and 6 d in media with varying ionic strengths (Milli-Q water: approx. 0.00 mmol/L and ASTM: 9.25 mmol/L) in the presence or absence of natural organic matter (NOM). Irrespective of the other parameters, aging in Milli-Q did not change the acute toxicity relative to an unaged control. In contrast, 6 d aged nTiO.sub.2 in ASTM without NOM caused a fourfold decreased acute toxicity. Relative to the 0 d aged particles, nTiO.sub.2 aged for 1 and 3 d in ASTM with NOM, which is the most environmentally-relevant setup used here, significantly increased acute toxicity (by approximately 30%), while a toxicity reduction (60%) was observed for 6 d aged nTiO.sub.2 . Comparable patterns were observed during the chronic experiments. A likely explanation for this phenomenon is that the aging of nTiO.sub.2 increases the particle size at the start of the experiment or the time of the water exchange from 100 nm to approximately 500 nm, which is the optimal size range to be taken up by filter feeding D. magna. If subjected to further agglomeration, larger nTiO.sub.2 particles, however, cannot be retained by the daphnids filter apparatus ultimately reducing their ecotoxicological potential. This non-linear pattern of increasing and decreasing nTiO.sub.2 related toxicity over the aging duration, highlights the knowledge gap regarding the underlying mechanisms and processes. This understanding seems, however, fundamental to predict the risks of nanoparticles in the field.
    Keywords: Nanoparticles ; Toxicity ; Humic Acids ; Titanium Dioxide
    ISSN: 1932-6203
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: PLoS ONE, 01 January 2013, Vol.8(11), p.e80960
    Description: Due to their surface characteristics, nanosized titanium dioxide particles (nTiO2) tend to adhere to biological surfaces and we thus hypothesize that they may alter the swimming performance and behavior of motile aquatic organisms. However, no suitable approaches to address these impairments in swimming behavior as a result of nanoparticle exposure are available. Water fleas Daphnia magna exposed to 5 and 20 mg/L nTiO2 (61 nm; polydispersity index: 0.157 in 17.46 mg/L stock suspension) for 96 h showed a significantly (p〈0.05) reduced growth rate compared to a 1-mg/L treatment and the control. Using three-dimensional video observations of swimming trajectories, we observed a treatment-dependent swarming of D. magna in the center of the test vessels during the initial phase of the exposure period. Ensemble mean swimming velocities increased with increasing body length of D. magna, but were significantly reduced in comparison to the control in all treatments after 96 h of exposure. Spectral analysis of swimming velocities revealed that high-frequency variance, which we consider as a measure of swimming activity, was significantly reduced in the 5- and 20-mg/L treatments. The results highlight the potential of detailed swimming analysis of D. magna for the evaluation of sub-lethal mechanical stress mechanisms resulting from biological surface coating and thus for evaluating the effects of nanoparticles in the aquatic environment.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 4
    In: Environmental Toxicology and Chemistry, July 2016, Vol.35(7), pp.1766-1774
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://onlinelibrary.wiley.com/doi/10.1002/etc.3325/abstract Byline: Ricki R. Rosenfeldt, Frank Seitz, Ann-Cathrin Haigis, Johanna Hoger, Jochen P. Zubrod, Ralf Schulz, Mirco Bundschuh Abstract Titanium dioxide nanoparticles (TiO.sub.2-NPs) adsorb co-occurring heavy metals in surface waters, modulating their toxicity for freshwater invertebrates. The processes triggering this interaction may be influenced by several environmental parameters; however, their relative importance remains unclear. The present study assessed the implications of aging on the joint acute toxicity of copper (Cu) and TiO.sub.2-NPs for Daphnia magna over a duration of up to 72h. The influences of aging duration as well as ionic strength, pH, and presence of different qualities of organic matter during aging were assessed. The results indicated that the presence of TiO.sub.2-NPs often reduced the Cu-induced toxicity for daphnids after aging (albeit with varying extent), which was displayed by up to 3-fold higher EC50 (50% effective concentration) values compared to the absence of TiO.sub.2-NPs. Moreover, the Cu speciation, influenced by the ionic composition and the pH as well as the presence of organic additives in the medium, strongly modulated the processes during aging, with partly limited implications of the aging duration on the ecotoxicological response of D. magna. Nonetheless, the present study underpins the potential of TiO.sub.2-NPs to modify toxicity induced by heavy metals in freshwater ecosystems under various environmental conditions. This pattern, however, needs further verification using heavy metal ions with differing properties in combination with further environmental factors, such as ultraviolet irradiation. Environ Toxicol Chem 2016;35:1766-1774. [c] 2015 SETAC Supporting information: Additional Supporting Information may be found in the online version of this article This article includes online-only Supplemental Data. CAPTION(S): Supporting Information.
    Keywords: Environmental Parameter ; Adsorption ; Mixture Toxicity ; Factorial Approach ; Crustacean
    ISSN: 0730-7268
    E-ISSN: 1552-8618
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  • 5
    In: Environmental Toxicology and Chemistry, August 2017, Vol.36(8), pp.2178-2189
    Description: Byline: Jochen P. Zubrod, Dominic Englert, Jakob Wolfram, Ricki R. Rosenfeldt, Alexander Feckler, Rebecca Bundschuh, Frank Seitz, Marco Konschak, Patrick Baudy, Simon Luderwald, Patrick Fink, Andreas Lorke, Ralf Schulz, Mirco Bundschuh Abstract Leaf litter is a major source of carbon and energy for stream food webs, while both leaf-decomposing microorganisms and macroinvertebrate leaf shredders can be affected by fungicides. Despite the potential for season-long fungicide exposure for these organisms, however, such chronic exposures have not yet been considered. Using an artificial stream facility, effects of a chronic (lasting up to 8 wk) exposure to a mixture of 5 fungicides (sum concentration 20I1/4g/L) on leaf-associated microorganisms and the key leaf shredder Gammarus fossarum were therefore assessed. While bacterial density and microorganism-mediated leaf decomposition remained unaltered, fungicide exposure reduced fungal biomass ([less than or equal to]71%) on leaves from day 28 onward. Gammarids responded to the combined stress from consumption of fungicide-affected leaves and waterborne exposure with a reduced abundance ([less than or equal to]18%), which triggered reductions in final population biomass (18%) and in the number of precopula pairs ([less than or equal to]22%) but could not fully explain the decreased leaf consumption (19%), lipid content ([less than or equal to]43%; going along with an altered composition of fatty acids), and juvenile production (35%). In contrast, fine particulate organic matter production and stream respiration were unaffected. Our results imply that long-term exposure of leaf-associated fungi and shredders toward fungicides may result in detrimental implications in stream food webs and impairments of detrital material fluxes. These findings render it important to understand decomposer communities' long-term adaptational capabilities to ensure that functional integrity is safeguarded. Environ Toxicol Chem 2017;36:2178-2189. [c] 2017 SETAC Supporting information: Additional Supporting Information may be found in the online version of this article This article includes online-only Supplemental Data. CAPTION(S): Supporting Data.
    Keywords: Aquatic Hyphomycetes ; Chronic Exposure ; Gammarus Fossarum ; Leaf Litter Breakdown ; Population Development
    ISSN: 0730-7268
    E-ISSN: 1552-8618
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  • 6
    Language: English
    In: Bulletin of Environmental Contamination and Toxicology, 2019, Vol.102(3), pp.303-309
    Description: The leaf-shredding crustacean Hyalella azteca , which is indigenous to Northern and Central America, is used to assess environmental risks associated with (metal-)contaminated sediments and to propose sediment quality standards also in Europe. Yet, it is unknown if H. azteca is protective for European crustacean shredders. We thus compared the sensitivity of H. azteca with that of the European species Asellus aquaticus and Gammarus fossarum towards copper- and cadmium-contaminated sediments (prepared according to OECD 218) under laboratory conditions employing mortality and leaf consumption as endpoints. H. azteca either reacted approximately fourfold more sensitive than the most tolerant tested species (as for cadmium) or its sensitivity was only 1.6 times lower than the highest sensitivity determined (as for copper), which should be covered by safety factors applied during risk assessments. Therefore, the results for the sediment type and the two heavy metals tested during the present study in combination with the existence of standardized testing protocols, their ease of culture, and short generation time, suggest H. azteca as suitable crustacean model shredder for assessing the toxicity of sediment-associated metals in Europe.
    Keywords: Body burden ; Ecosystem functioning ; Metals ; Sediment toxicity tests ; Shredders
    ISSN: 0007-4861
    E-ISSN: 1432-0800
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