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  • Titanium
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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: 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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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    Language: English
    In: Environmental Pollution, March 2014, Vol.186, pp.136-140
    Description: 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 ; 〈100 nm) on the interaction between the prey (Ephemeroptera) and the predator (Amphipoda) over 96 h considering UV-irradiation at field relevant levels (approximately 11.4 W/m ) as an additional environmental factor (  = 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 alone, while the combination of nTiO 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 . The present study, hence, highlights the importance to cover UV-irradiation during the risk assessment of nanoparticles. UV-irradiation influences nanoparticles' ecotoxicity rising concerns about adverse effects in trophic interactions and ecosystem functions.
    Keywords: Gammarid ; Mayfly ; Energy Transfer ; Ecosystem Functioning ; Sunlight ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 8
    Language: English
    In: Environmental science & technology, 17 June 2014, Vol.48(12), pp.6965-72
    Description: Unintentionally released titanium dioxide nanoparticles (nTiO2) may co-occur in aquatic environments together with other stressors, such as, metal ions. The effects of P25-nTiO2 on the toxicity and uptake of the elements silver (Ag), arsenic (As) and copper (Cu) were assessed by applying a factorial test design. The test design consisted of two developmental stages of Daphnia magna, two levels of nTiO2 (0 versus 2 mg/L) as well as seven nominal test concentrations of the respective element. The presence of nTiO2 increased Ag toxicity for juveniles as indicated by a 40% lower 72-h EC50, while the toxicities of As and Cu were reduced by up to 80%. This reduction was even more pronounced for Cu in the presence of dissolved organic carbon (i.e., seaweed extract) and nTiO2. This outcome coincides with the body burden of the elements, which was elevated 2-fold for Ag and decreased 14-fold for Cu in the presence of nTiO2. Although the underlying mechanisms could not be uncovered, the data suggest that the carrier function of nTiO2 plays a central role. However, to understand the processes and mechanisms occurring in the field due to the presence of nTiO2 further systematic investigations considering environmental variables and nanoparticle characteristics are required.
    Keywords: Toxicity Tests ; Daphnia -- Drug Effects ; Metals, Heavy -- Toxicity ; Nanoparticles -- Chemistry ; Titanium -- Chemistry
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 9
    Language: English
    In: Environmental science & technology, 03 February 2015, Vol.49(3), pp.1815-22
    Description: Titanium dioxide nanoparticles (nTiO2) are expected to interact with natural substances and other chemicals in the environment, however little is known about their combined effects. Therefore, this study assessed the toxicity of copper (Cu) in combination with varying crystalline phases (anatase, rutile, and the mixture) of nTiO2 and differing organic materials on Daphnia magna. The nanoparticles reduced the Cu-toxicity depending on the product (0.3- to 2-fold higher 48-h EC50). This decrease in toxicity coincided with a lowered Cu-concentration in the water column, which was driven by the adsorption of Cu to nTiO2-depending on available surface area and structure-and their subsequent sedimentation. In the presence of organic material and nTiO2, the Cu-toxicity was further reduced (up to 7-fold higher 48-h EC50). This observation can be explained by a reduced Cu-bioavailability as a result of complexation and adsorption by the organic material and nTiO2, respectively. Thus, the crystalline phase composition, which is determining the surface area and structure of nTiO2, seems to be of major importance for the toxicity reduction of heavy metals, while the influence of the organic materials was mainly driven by the quantity and quality of humic substances.
    Keywords: Humic Substances ; Copper -- Toxicity ; Nanoparticles -- Chemistry ; Titanium -- Chemistry ; Water Pollutants, Chemical -- Toxicity
    ISSN: 0013936X
    E-ISSN: 1520-5851
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  • 10
    Language: English
    In: Environmental pollution (Barking, Essex : 1987), January 2015, Vol.196, pp.276-83
    Description: Interactions with environmental parameters may alter the ecotoxicity of nanoparticles. The present study therefore assessed the (in)direct effects of nanoparticulate titanium dioxide (nano-TiO(2)) towards Gammarus fossarum, considering nano-TiO(2)'s photocatalytic properties at ambient UV-intensities. Gammarids' habitat selection was investigated using its feeding preference on leaf discs either exposed to or protected from UV-irradiation in presence of nano-TiO(2) as proxy (n = 49). UV-irradiational one induced a significant preference for UV-protected habitats, which was more pronounced in simultaneous presence of nano-TiO(2). This behaviour may be mainly explained by the UV-induced formation of reactive oxygen species (ROS) by nano-TiO(2). Besides their direct toxicity, ROS may have lowered the leaf-quality in UV-exposed areas contributing (approximately 30%) to the observed behavioural pattern. Since the predicted no effect concentration of nano-TiO(2) in combination with UV irradiation falls below the predicted environmental concentration this study underpins the importance of considering environmental parameters during the risk assessment of nanoparticles.
    Keywords: Ecosystem ; Photochemical Processes ; Aquatic Organisms -- Physiology ; Nanoparticles -- Chemistry ; Titanium -- Chemistry ; Water Pollutants, Chemical -- Chemistry
    E-ISSN: 1873-6424
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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