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  • Nanoparticles
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  • 1
    Language: English
    In: Environmental Pollution, March, 2014, Vol.186, p.136(5)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.envpol.2013.11.028 Byline: Gabriela KalAikova, Dominic Englert, Ricki R. Rosenfeldt, Frank Seitz, Ralf Schulz, Mirco Bundschuh Abstract: Although nanoparticle production and application increases continuously, their implications in species interactions, especially in combination with other environmental stressors, are rarely assessed. Therefore, the present study investigated the influence of 2 mg/L titanium dioxide nanoparticles (nTiO.sub.2; 〈100 nm) on the interaction between the prey Ephemerella ignita (Ephemeroptera) and the predator Gammarus fossarum (Amphipoda) over 96 h considering UV-irradiation at field relevant levels (approximately 11.4 W/m.sup.2) as an additional environmental factor (n = 16). At the same time, gammarid's consumption of an alternative food source, i.e. leaf discs, was assessed. All endpoints covered were not affected by nTiO.sub.2 alone, while the combination of nTiO.sub.2 and UV caused a reduction in gammarid's predation (68%), leaf consumption (60%) and body weight (22%). These effects were most likely triggered by the UV-induced formation of reactive oxygen species by nTiO.sub.2. The present study, hence, highlights the importance to cover UV-irradiation during the risk assessment of nanoparticles. Author Affiliation: (a) Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, D-76829 Landau, Germany (b) Faculty of Chemistry and Chemical Technology, University of Ljubljana, AA kerAeva 5, SI-1000 Ljubljana, Slovenia (c) Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Lennart Hjelms vag 9, 750 07 Uppsala, Sweden Article History: Received 24 September 2013; Revised 6 November 2013; Accepted 18 November 2013
    Keywords: Nanoparticles ; Titanium Dioxide
    ISSN: 0269-7491
    Source: Cengage Learning, Inc.
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  • 2
    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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  • 3
    Language: English
    In: The Science of the Total Environment, Sept 15, 2014, Vol.493, p.891(7)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.scitotenv.2014.06.092 Byline: Frank Seitz, Ricki R. Rosenfeldt, Sandra Schneider, Ralf Schulz, Mirco Bundschuh Abstract: Nanoparticle toxicity depends amongst others on particle characteristics and nanoparticle behavior during their aquatic life cycle. Aquatic organisms may be exposed to nanoparticle agglomerates of varying size, while lager agglomerates after settling rather affect benthic organisms. In this context, the present study systematically examined the role of particle characteristics, i.e. crystalline structure composition (anatase as well as mixture of anatase-rutile), initial particle size (55-, 100-, and 140-nm) and surface area, in the toxicity of titanium dioxide nanoparticles (nTiO.sub.2) to the pelagic filter feeder Daphnia magna (n=4) and the benthic amphipod Gammarus fossarum (n=30). Smaller initial particle sizes (i.e. 55-nm) and anatase based particles showed an approximately 90% lower Daphnia EC.sub.50-value compared to its respective counterpart. Most importantly, particle surface normalized EC.sub.50-values significantly differed for nanoparticles equal to or below 100 nm in size from 140-nm sized particles. Hence, these data suggest that the reactive initial surface area may explain the ecotoxicological potential of different particle size classes only if their size is smaller or around 100nm. In contrast to Daphnia, Gammarus was not affected by nTiO.sub.2 concentrations of up to 5.00mg/L, irrespective of their characteristics. This indicates fundamental differences in the toxicity of nTiO.sub.2 during its aquatic life cycle mediated by alterations in their characteristics over time. Article History: Received 27 May 2014; Revised 19 June 2014; Accepted 20 June 2014 Article Note: (miscellaneous) Editor: D. Barcelo
    Keywords: Nanoparticles -- Analysis ; Crystal Structure -- Analysis ; Titanium Dioxide -- Analysis
    ISSN: 0048-9697
    Source: Cengage Learning, Inc.
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  • 4
    Language: English
    In: Environmental Pollution, July 2016, Vol.214, pp.840-846
    Description: Although nanoparticles are increasingly investigated, their impact on the availability of food (i.e., algae) at the bottom of food chains remains unclear. It is, however, assumed that algae, which form heteroagglomerates with nanoparticles, sediment quickly limiting the availability of food for primary consumers such as As a consequence, it may be hypothesized that this scenario – in case of fundamental importance for the nanoparticles impact on primary consumers – induces a similar pattern in the life history strategy of daphnids relative to situations of food depletion. To test this hypothesis, the present study compared the life-history strategy of experiencing different degrees of food limitation as a consequence of variable algal density with daphnids fed with heteroagglomerates composed of algae and titanium dioxide nanoparticles (nTiO ). In contrast to the hypothesis, daphnids’ body length, weight, and reproduction increased when fed with these heteroagglomerates, while the opposite pattern was observed under food limitation scenarios. Moreover, juvenile body mass, and partly length, was affected negatively irrespective of the scenarios. This suggests that daphnids experienced – besides a limitation in the food availability – additional stress when fed with heteroagglomerates composed of algae and nTiO Potential explanations include modifications in the nutritious quality of algae but also an early exposure of juveniles to nTiO . Impact of nTiO -algae heteroagglomerates in 's life history strategy cannot exclusively be explained by food depletion.
    Keywords: Energy Budget ; Heteroagglomerates ; Trophic Interaction ; Physiology ; Food Quality ; Nanomaterials ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 5
    In: Freshwater Biology, December 2016, Vol.61(12), pp.2185-2196
    Description: Ecotoxicology is often criticised for its simplistic approach, which does not normally consider the complexity of field conditions. Simple laboratory experiments can still be useful, however, especially for assessing effects of emerging stressors such as nanoparticles, which exhibit fates, exposure profiles and modes of action substantially different from those of traditional chemicals. Here we argue that it is important to understand the potential effects of environmental conditions (e.g. UV radiation, dissolved organic matter, chemical stressors) on the fate and ecotoxicological potential of nanoparticles by using simple and well‐controlled experiments, while aiming to mimic realistic environmental conditions as closely as possible. The observation that increasingly complex test systems may yield lower effect thresholds for nanoparticles than standardised tests suggests that current approaches require modification. Specifically, research is encouraged on interactions among trophic levels, community composition and ecosystem and evolutionary processes, so that effects observed in complex environmental settings can be explained mechanistically. We highlight recent discoveries in ecotoxicology and ecology that suggest nanoparticle‐induced consequences on evolutionary and ecosystem processes as well as their potential transfer across ecosystem boundaries. These insights may encourage further research on nanoparticle effects informed by ecological theory.
    Keywords: Environmental Variables ; Mechanism Of Toxicity ; Mixture Toxicity ; Nanomaterial ; Trophic Interaction
    ISSN: 0046-5070
    E-ISSN: 1365-2427
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  • 6
    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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  • 7
    Language: English
    In: Chemosphere, 2011, Vol.85(10), pp.1563-1567
    Description: ► Effects of nTiO and ambient UV-irradiation affect representatives of detrital food webs. ► Accumulation of nTiO at the bottom of the test vessel seems to affect ecotoxicity. ► nTiO and ambient UV-irradiation increases ecotoxicity due to the formation of ROS. Production and use of engineered nanoparticles, such as titanium dioxide nanoparticles (nTiO ), is increasing worldwide, enhancing their probability to enter aquatic environments. However, direct effects of nTiO as well as ecotoxicological consequences due to the interactions of nTiO with environmental factors like ultraviolet (UV) irradiation on representatives of detrital food webs have not been assessed so far. Hence, the present study displayed for the first time adverse sublethal effects of nTiO at concentrations as low as 0.2 mg L on the leaf shredding amphipod both in presence and absence of ambient UV-irradiation following a 7-d exposure. In absence of UV-irradiation, however, the effects seemed to be driven by accumulation of nTiO at the bottom of the test vessels to which the gammarids were potentially exposed. The adverse sublethal and lethal effects on gammarids caused by the combined application of nTiO and ambient UV-irradiation are suggested to be driven by the formation of reactive oxygen species. In conclusion, both the accumulation of nTiO at the bottom of the test vessel and the UV induced formation of reactive oxygen species clearly affected its ecotoxicity, which is recommended for consideration in the environmental risk assessment of nanoparticles.
    Keywords: Nanoparticle ; Titanium Dioxide ; Ultraviolet Irradiation ; Gammarus Fossarum ; Accumulation ; Reactive Oxygen Species ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 8
    Language: English
    In: Science of the Total Environment, 15 September 2014, Vol.493, pp.891-897
    Description: Nanoparticle toxicity depends amongst others on particle characteristics and nanoparticle behavior during their aquatic life cycle. Aquatic organisms may be exposed to nanoparticle agglomerates of varying size, while lager agglomerates after settling rather affect benthic organisms. In this context, the present study systematically examined the role of particle characteristics, i.e. crystalline structure composition (anatase as well as mixture of anatase-rutile), initial particle size (55-, 100-, and 140-nm) and surface area, in the toxicity of titanium dioxide nanoparticles (nTiO ) to the pelagic filter feeder (n = 4) and the benthic amphipod (n = 30). Smaller initial particle sizes (i.e. 55-nm) and anatase based particles showed an approximately 90% lower EC -value compared to its respective counterpart. Most importantly, particle surface normalized EC -values significantly differed for nanoparticles equal to or below 100 nm in size from 140-nm sized particles. Hence, these data suggest that the reactive initial surface area may explain the ecotoxicological potential of different particle size classes only if their size is smaller or around 100 nm. In contrast to , was not affected by nTiO concentrations of up to 5.00 mg/L, irrespective of their characteristics. This indicates fundamental differences in the toxicity of nTiO during its aquatic life cycle mediated by alterations in their characteristics over time.
    Keywords: Daphnia Magna ; Gammarus Fossarum ; Crystallinity ; Toxicity ; Crustacea ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 9
    Language: English
    In: PLoS ONE, 01 January 2015, Vol.10(5), p.e0126021
    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 (nTiO2; ~90 nm) on the standard test species Daphnia magna by following the respective test guidelines. The nTiO2 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 nTiO2 in ASTM without NOM caused a fourfold decreased acute toxicity. Relative to the 0 d aged particles, nTiO2 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 nTiO2. Comparable patterns were observed during the chronic experiments. A likely explanation for this phenomenon is that the aging of nTiO2 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 nTiO2 particles, however, cannot be retained by the daphnids' filter apparatus ultimately reducing their ecotoxicological potential. This non-linear pattern of increasing and decreasing nTiO2 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: Sciences (General)
    E-ISSN: 1932-6203
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  • 10
    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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