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  • Daphnia Magna
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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: 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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  • 4
    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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  • 5
    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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  • 6
    Language: English
    In: Aquatic toxicology, 2013, Vol.126, pp.163-168
    Description: The increasing use of titanium dioxide nanoparticles (nTiO₂) inevitably results in their release into the environment, raising concerns about potential adverse effects in wildlife. By following standard test protocols, several studies investigated the ecotoxicity of nTiO₂ among others to Daphnia magna. These studies indicated a large variability – several orders of magnitude – in the response variables. However, other factors, like nanoparticle characteristics and test design, potentially triggering these differences, were largely ignored. Therefore, the present study assessed the chronic ecotoxicity of two nTiO₂ products with varying crystalline structure (A-100; P25) to D. magna. A semi-static and a flow-through exposure scenario were compared, ensuring that both contained environmentally relevant concentrations of dissolved organic carbon. Utilizing the semi-static test design, a concentration as low as 0.06mg/L A-100 (∼330nm) significantly reduced the reproduction of daphnia indicating environmental risk. In contrast, no implication in the number of released offspring was observed during the flow-through experiment with A-100 (∼140nm). Likewise, P25 (∼130nm) did not adversely affect reproduction irrespective of the test design utilized. Given the present study's results, the particle size, the product composition, i.e. the crystalline structure, and the accumulation of nTiO₂ at the bottom of the test vessel – the latter is relevant for a semi-static test design – may be suggested as factors potentially triggering differences in nTiO₂ toxicity to D. magna. Hence, these factors should be considered to improve environmental risk assessment of nanoparticles. ; p. 163-168.
    Keywords: Particle Size ; Progeny ; Titanium Dioxide ; Dissolved Organic Carbon ; Exposure Scenario ; Wildlife ; Crystal Structure ; Reproduction ; Daphnia Magna ; Risk ; Ecotoxicology ; Toxicity ; Adverse Effects ; Nanoparticles
    ISSN: 0166-445X
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 7
    Language: English
    In: Aquatic Toxicology, 15 January 2013, Vol.126, pp.163-168
    Description: ► nTiO concentrations one order of magnitude above the PEC caused adverse chronic effects. ► Particle size and product composition, i.e. crystalline structure, trigger differences in nTiO toxicity. ► nTiO accumulation at the bottom of the test vessel is an important effect pathway. ► Dissolved organic carbon influences fate and finally nTiO toxicity. The increasing use of titanium dioxide nanoparticles (nTiO ) inevitably results in their release into the environment, raising concerns about potential adverse effects in wildlife. By following standard test protocols, several studies investigated the ecotoxicity of nTiO among others to . These studies indicated a large variability – several orders of magnitude – in the response variables. However, other factors, like nanoparticle characteristics and test design, potentially triggering these differences, were largely ignored. Therefore, the present study assessed the chronic ecotoxicity of two nTiO products with varying crystalline structure (A-100; P25) to . A semi-static and a flow-through exposure scenario were compared, ensuring that both contained environmentally relevant concentrations of dissolved organic carbon. Utilizing the semi-static test design, a concentration as low as 0.06 mg/L A-100 (∼330 nm) significantly reduced the reproduction of daphnia indicating environmental risk. In contrast, no implication in the number of released offspring was observed during the flow-through experiment with A-100 (∼140 nm). Likewise, P25 (∼130 nm) did not adversely affect reproduction irrespective of the test design utilized. Given the present study's results, the particle size, the product composition, i.e. the crystalline structure, and the accumulation of nTiO at the bottom of the test vessel – the latter is relevant for a semi-static test design – may be suggested as factors potentially triggering differences in nTiO toxicity to . Hence, these factors should be considered to improve environmental risk assessment of nanoparticles.
    Keywords: Inorganic Nanoparticles ; Reproduction ; Growth ; Flow-through ; Crustacea ; Chemistry ; Ecology
    ISSN: 0166-445X
    E-ISSN: 1879-1514
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  • 8
    Language: English
    In: Environmental Science and Pollution Research, 2013, Vol.20(10), pp.7341-7347
    Description: Although generally misunderstood, the p value is the probability of the test results or more extreme results given H 0 is true: it is not the probability of H 0 being true given the results. To obtain directly useful insight about H 0 , the positive predictive value (PPV) and the negative predictive value (NPV) may be useful extensions of null hypothesis significance testing (NHST). They provide information about the probability of statistically significant and non-significant test outcomes being true based on an a priori defined biologically meaningful effect size. The present study explores the utility of PPV and NPV in an ecotoxicological context by using the frequently applied Daphnia magna reproduction test (OECD guideline 211) and the chemical stressor lindane as a model system. The results indicate that especially the NPV deviates meaningfully between a test design strictly following the guideline and an experimental procedure controlling for α and β at the level of 0.05. Consequently, PPV and NPV may be useful supplements to NHST that inform the researcher about the level of confidence warranted by both statistically significant and non-significant test results. This approach also reinforces the value of considering α , β , and a biologically meaningful effect size a priori.
    Keywords: Sample size ; Bayesian ; Power analysis ; Effect size ; Type I error rate ; Type II error rate
    ISSN: 0944-1344
    E-ISSN: 1614-7499
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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: Nanotoxicology, 25 November 2016, Vol.10(10), pp.1415-1421
    Description: Nanoparticles' fate is amongst other parameters determined by the quantity and quality of natural organic matter (NOM). Consequently, the ecotoxicity of nanoparticles is modified, while only little information is available on the NOM characteristics triggering this interplay. This study systematically...
    Keywords: Crustacea ; Dissolved Organic Matter ; Suva ; Suwannee River ; Toxicity Mitigation ; Pharmacy, Therapeutics, & Pharmacology
    ISSN: 1743-5390
    E-ISSN: 1743-5404
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