Ecotoxicity characterization assisted performance assessment of electro-bioremediation reactors for nitrate and arsenite elimination.

The performance of combined reduction of nitrate (NO3 - ) to dinitrogen gas (N2 ) and oxidation of arsenite (As[III]) to arsenate (As[V]) by a bioelectrochemical system was assessed, supported by ecotoxicity characterization. For the comprehensive toxicity characterization of the untreated model groundwater and the treated reactor effluents, a problem-specific ecotoxicity test battery was established. The performance of the applied technology in terms of toxicity and target pollutant elimination was compared and analyzed. The highest toxicity attenuation was achieved under continuous flow mode with hydraulic retention time (HRT) = 7.5 h, with 95%, nitrate removal rate and complete oxidation of arsenite to arsenate. Daphnia magna proved to be the most sensitive test organism. The results of the D. magna lethality test supported the choice of the ideal operational conditions based on chemical data analysis. The outcomes of the study demonstrated that the applied technology was able to improve the groundwater quality in terms of both chemical and ecotoxicological characteristics. The importance of ecotoxicity evaluation was also highlighted, given that significant target contaminant elimination did not necessarily lower the environmental impact of the initial, untreated medium, in addition, anomalies might occur during the technology operational process which in some instances, could result in elevated toxicity levels.

Effects of the water-soluble fraction of a crude oil on freshwater meiofauna and nematode assemblages.

Oil water-soluble fractions (WSFs) compounds have low persistence in water; evaporating in a matter of hours to days. Nonetheless, they pose high toxicity to exposed biota. Their effects may be instantaneous or delayed, affecting, respectively, mainly survival vs growth and reproduction. We investigated the effects of crude oil WSFs on freshwater meiobenthos, with a focus on nematode assemblages, in community microcosm experiments lasting 15 weeks. Treatments consisted of the application of different concentrations of oil WSFs, i.e. high (100%) medium (50%) and low (10%), and effects were assessed one, three, nine and 15 weeks after contamination, allowing us to detect both short-term and lasting effects of oil-WSF. Additionally, we compared the effects of a single contamination event with those of a so-called 'constant' oil-WSF contamination where we replenished evaporated water with water containing the medium concentration of oil WSF. Next to nematodes, the most abundant meiofaunal taxa were rotifers, gastrotrichs, oligochaetes and tardigrades. Total abundance, different diversity indices, the composition of feeding-types and the age structure were investigated in the assessment of direct oil effects on the structure of nematode assemblages. Limited immediate effects were observed, except for a significant decrease of the index of taxonomic distinctness, which already appeared in the first week. Significant impacts on total nematode abundance, diversity and species composition only became apparent after 9-15 weeks of incubation, indicating that delayed effects of a single exposure are far more pronounced than instantaneous effects. Moreover, for most response variables, the strongest impacts were not observed in the highest-concentration treatment, but in a medium-concentration treatment with regular replenishment of oil WSF, suggesting that internal exposure may be important in generating effects. Furthermore, the predictability of the sensitivity of individual species was sometimes poor, which may not only result from these species' sensitivities, but also from alterations in interspecific interactions in polluted communities. Further toxicity tests should be carried out in order to unravel the main modes of action of crude oil WSF which lead to the observed long-term sublethal effects on nematode communities.

The unrecognized occupational relevance of the interaction between engineered nanomaterials and the gastro-intestinal tract: a consensus paper from a multidisciplinary working group.

BACKGROUND: There is a fundamental gap of knowledge on the health effects caused by the interaction of engineered nanomaterials (ENM) with the gastro-intestinal tract (GIT). This is partly due to the incomplete knowledge of the complex physical and chemical transformations that ENM undergo in the GIT, and partly to the widespread belief that GIT health effects of ENM are much less relevant than pulmonary effects. However, recent experimental findings, considering the role of new players in gut physiology (e.g. the microbiota), shed light on several outcomes of the interaction ENM/GIT. Along with this new information, there is growing direct and indirect evidence that not only ingested ENM, but also inhaled ENM may impact on the GIT. This fact, which may have relevant implications in occupational setting, has never been taken into consideration. This review paper summarizes the opinions and findings of a multidisciplinary team of experts, focusing on two main aspects of the issue: 1) ENM interactions within the GIT and their possible consequences, and 2) relevance of gastro-intestinal effects of inhaled ENMs. Under point 1, we analyzed how luminal gut-constituents, including mucus, may influence the adherence of ENM to cell surfaces in a size-dependent manner, and how intestinal permeability may be affected by different physico-chemical characteristics of ENM. Cytotoxic, oxidative, genotoxic and inflammatory effects on different GIT cells, as well as effects on microbiota, are also discussed. Concerning point 2, recent studies highlight the relevance of gastro-intestinal handling of inhaled ENM, showing significant excretion with feces of inhaled ENM and supporting the hypothesis that GIT should be considered an important target of extrapulmonary effects of inhaled ENM. CONCLUSIONS: In spite of recent insights on the relevance of the GIT as a target for toxic effects of nanoparticles, there is still a major gap in knowledge regarding the impact of the direct versus indirect oral exposure. This fact probably applies also to larger particles and dictates careful consideration in workers, who carry the highest risk of exposure to particulate matter.

Adaption and application of cell-based bioassays to whole-water samples.

The increasing presence of contaminants of emerging concern in wastewater and their potential environmental risks require improved monitoring and analysis methods. Direct toxicity assessment (DTA) using bioassays can complement chemical analysis of wastewater discharge, but traditional in vivo tests have ethical considerations and are expensive, low-throughput, and limited to apical endpoints (mortality, reproduction, development, and growth). In vitro bioassays offer an alternative approach that is cheaper, faster, and more ethical, and can provide higher sensitivity for some environmentally relevant endpoints. This study explores the potential benefits of using whole water samples of wastewater and environmental surface water instead of traditional solid phase extraction (SPE) methods for in vitro bioassays testing. Whole water samples produced a stronger response in most bioassays, likely due to the loss or alteration of contaminants during SPE sample extraction. In addition, there was no notable difference in results for most bioassays after freezing whole water samples, which allows for increased flexibility in testing timelines and cost savings. These findings highlight the potential advantages of using whole water samples in DTA and provide a framework for future research in this area.

Ecotoxicity attenuation by acid-resistant nanofiltration in scandium recovery from TiO2 production waste.

The lack of high-grade scandium (Sc) ores and recovery strategies has stimulated research on the exploitation of non-ore-related secondary sources that have great potential to safeguard the critical raw materials supply of the EU's economy. Waste materials may satisfy the growing global Sc demand, specifically residues from titanium dioxide (TiO2) production. New technologies are being developed for the recovery of Sc from such residues; however, the possible environmental impacts of intermediary products and residues are usually not considered. In order to provide a comprehensive ecotoxicity characterisation of the wastes and intermediate residues resulting from one promising new technology, acid-resistant nanofiltration (arNF), a waste-specific ecotoxicity toolkit was established. Three ecotoxicity assays were selected with specific test parameters providing the most diverse outcome for toxicity characterisation at different trophic levels: Aliivibrio fischeri (bacteria) bioluminescence inhibition (30 min exposure), Daphnia magna (crustacean) lethality and immobilisation (24 h exposure) and Lemna minor (plant) growth inhibition with determination of the frond number (7 d exposure). According to our results, the environmental impact of the generated intermediate and final residues on the aquatic ecosystem was mitigated by the consecutive steps of the filtration methods applied. High and statistically significant toxicity attenuation was achieved according to each test organism: toxicity was lowered based on EC20 values, according to the A. fischeri bioluminescence inhibition assay (by 97%), D. magna lethality (by 99%) and L. minor frond number (by 100%), respectively, after the final filtration step, nanofiltration, in comparison to the original waste. Our results underline the importance of assessing chemical technologies' ecotoxicological and environmental impacts with easy-to-apply and cost-effective test methods to showcase the best available technologies.

Review of ecologically relevant in vitro bioassays to supplement current in vivo tests for whole effluent toxicity testing - Part 1: Apical endpoints.

Whole effluent toxicity (WET) testing is commonly used to ensure that wastewater discharges do not pose an unacceptable risk to receiving environments. Traditional WET testing involves exposing animals to (waste)water samples to assess four major ecologically relevant apical endpoints: mortality, growth, development, and reproduction. Recently, with the widespread implementation of the 3Rs to replace, reduce and refine the use of animals in research and testing, there has been a global shift away from in vivo testing towards in vitro alternatives. However, prior to the inclusion of in vitro bioassays in regulatory frameworks, it is critical to establish their ecological relevance and technical suitability. This is part 1 of a two-part review that aims to identify in vitro bioassays that can be used in WET testing and relate them to ecologically relevant endpoints through toxicity pathways, providing the reader with a high-level overview of current capabilities. Part 1 of this review focuses on four apical endpoints currently included in WET testing: mortality, growth, development, and reproduction. For each endpoint, the link between responses at the molecular or cellular level, that can be measured in vitro, and the adverse outcome at the organism level were established through simplified toxicity pathways. Additionally, literature from 2015 to 2020 on the use of in vitro bioassays for water quality assessments was reviewed to identify a list of suitable bioassays for each endpoint. This review will enable the prioritization of relevant endpoints and bioassays for incorporation into WET testing.

Review of ecologically relevant in vitro bioassays to supplement current in vivo tests for whole effluent toxicity testing - Part 2: Non-apical endpoints.

Whole effluent toxicity (WET) testing uses whole animal exposures to assess the toxicity of complex mixtures, like wastewater. These assessments typically include four apical endpoints: mortality, growth, development, and reproduction. In the last decade, there has been a shift to alternative methods that align with the 3Rs to replace, reduce, and refine the use of animals in research. In vitro bioassays can provide a cost-effective, high-throughput, ethical alternative to in vivo assays. In addition, they can potentially include additional, more sensitive, environmentally relevant endpoints than traditional toxicity tests. However, the ecological relevance of these endpoints must be established before they are adopted into regulatory frameworks. This is Part 2 of a two-part review that aims to identify in vitro bioassays that are linked to ecologically relevant endpoints that could be included in WET testing. Part 2 of this review focuses on non-apical endpoints that should be incorporated into WET testing. In addition to the four apical endpoints addressed in Part 1, this review identified seven additional toxic outcomes: endocrine disruption, xenobiotic metabolism, carcinogenicity, oxidative stress, inflammation, immunotoxicity and neurotoxicity. For each, the response at the molecular or cellular level measured in vitro was linked to the response at the organism level through a toxicity pathway. Literature from 2015 to 2020 was used to identify suitable bioassays that could be incorporated into WET testing.

Not Only Systemin: Prosystemin Harbors Other Active Regions Able to Protect Tomato Plants.

Prosystemin is a 200-amino acid precursor expressed in Solanaceae plants which releases at the C-terminal part a peptidic hormone called Systemin in response to wounding and herbivore attack. We recently showed that Prosystemin is not only a mere scaffold of Systemin but, even when deprived of Systemin, is biologically active. These results, combined with recent discoveries that Prosystemin is an intrinsically disordered protein containing disordered regions within its sequence, prompted us to investigate the N-terminal portions of the precursor, which contribute to the greatest disorder within the sequence. To this aim, PS1-70 and PS1-120 were designed, produced, and structurally and functionally characterized. Both the fragments, which maintained their intrinsic disorder, were able to induce defense-related genes and to protect tomato plants against Botrytis cinerea and Spodoptera littoralis larvae. Intriguingly, the biological activity of each of the two N-terminal fragments and of Systemin is similar but not quite the same and does not show any toxicity on experimental non-targets considered. These regions account for different anti-stress activities conferred to tomato plants by their overexpression. The two N-terminal fragments identified in this study may represent new promising tools for sustainable crop protection.

Using an expert judgment response matrix to assess the risk of groundwater discharges from remediated fuel spill sites to the marine environment at sub-Antarctic Macquarie Island, Australia.

This study assesses toxicity of groundwater from remediated fuel spill sites, as the final phase of an environmental risk assessment of contaminated sites at sub-Antarctic Macquarie Island, Tasmania, Australia. To complement previous terrestrial ecotoxicological research, we determine risk to marine environments from residual biodegraded hydrocarbon contaminants in groundwater discharges. Direct toxicity assessments were conducted on 7 composite groundwater test solutions, adjusted to ambient seawater salinity. Eleven native marine invertebrates (from varied taxa: gastropods, bivalves, flatworms, amphipods, copepods, isopods) were exposed and observed for up to 21 d. Lethal time estimates (LT10, LT50) showed sensitivity was time dependent (LT10s = 4-15 d) and variable between species. Three species showed no response to any test solution, and most species did not respond for up to 5 d. Data were interpreted using an expert judgment response matrix with multiple lines of evidence to predict risk. No consistent patterns in the relative toxicity of test solutions, based on polar or nonpolar hydrocarbon concentrations, were identified. Although toxicity was observed in some species, this was only under worst-case conditions of undiluted, continuous, extended exposure. Natural dynamics of the site, including low groundwater discharge rates, high rainfall, and a highly energetic receiving environment, ensure groundwater is rapidly diluted and dispersed. In this context, and based on site conditions at the time of testing, these toxicity assessments provide robust evidence that residual contamination in groundwater at remediated sites at Macquarie Island is unlikely to represent a risk to the adjacent marine communities tested. Integr Environ Assess Manag 2021;17:785-801. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Removal of hazardous micropollutants from treated wastewater using cyclodextrin bead polymer - A pilot demonstration case.

Increasing amount of micropollutants such as drugs, cosmetics and nutritional supplements detected in surface waters represents increasing risk to humans and to the whole environment. These hazardous materials deriving mostly from wastewaters often cannot be effectively removed by conventional water treatment technologies due to their persistence. Some of the innovative technologies use specific sorbents for their removal. Cyclodextrin-based sorbents have already proved to be efficient in laboratory-scale experiments, but no pilot-plant scale demonstration has been performed so far. We are the first who applied this sorption-technology as a tertiary treatment in a pilot-plant scale operating, biomachine-type municipal wastewater treatment plant. As a result of the treatment 7 of 9 typical micropollutants (estradiol, ethinyl estradiol, estriol, diclofenac, ibuprofen, bisphenol A and cholesterol) were removed with >80% efficiency from effluent (reducing their concentration from ∼5 µg/L to <0.001-1 µg/L). GC-MS analysis of water samples showed that many of the micropollutants were removed from the water within a short time, demonstrating the high potential of the applied cyclodextrin-based sorbent in micropollutant removal. The effect-based testing also confirmed the efficiency. There was a correlation between sorption efficacies and binding constants of micropollutant/cyclodextrin inclusion complexes, showing that among others also inclusion complex formation of pollutants with cyclodextrin played important role in sorption mechanism.

Aluminum and vaccines: Current state of knowledge.

French people have never been so wary about vaccines. The use of aluminum salts in vaccine adjuvants to enhance effectiveness is one of the major reasons for this lack of confidence. The direct toxicity of aluminum is often put forward. Direct toxicity of aluminum has long been known-especially with occupational exposure-to be associated with characteristic clinical manifestations and increased blood aluminum level. Intoxication related to the excessive amount of an element in the body, whether be it lead poisoning following exposure to lead or mercury poisoning for instance, is always associated with metal increase in biological media. To date no link has been established between the direct toxicity of aluminum and vaccines. Aluminum levels in biological media of vaccinated subjects are not different from those of unvaccinated subjects. This is consistent with the very small amount of aluminum contained in one dose of vaccine. Indirect toxicity of aluminum was suggested to explain macrophagic myofasciitis in humans in 2011, a disease that could be mediated by an autoimmune/autoinflammatory mechanism. This hypothesis has recently been refuted in a large pharmaco-epidemiological study proving that aluminum-containing adjuvants of vaccines are not responsible for this autoimmune/autoinflammatory syndrome.

Tinnitus during and after childhood cancer: A systematic review.

BACKGROUND: Tinnitus can occur during and after treatment for childhood cancer. Studies on the occurrence of, and risk factors for tinnitus during and after childhood cancer treatment are scarce. The aim of this study is to get insight into the frequency and risk factors of tinnitus during and after childhood cancer therapy, based on a review of all previously reported literature. MATERIALS AND METHODS: Systematic electronic literature searches that combined childhood cancer with different treatments and tinnitus terms were performed in the databases EMBASE, Medline, Cochrane, Web of Science, and Google Scholar. Studies were included based on reporting the frequency of tinnitus during and/or after childhood cancer, with 75% of participants being under the age of 25 at time of diagnosis, diagnosed with any type of childhood malignancy and treated with any type of chemotherapy and/or radiotherapy. A risk of bias assessment per research question was performed. RESULTS: Tinnitus incidence rates were reported up to 15.9 (95% CI 11.8-21.4) during therapy and up to 5.4 (95% CI 4.3-6.9) more than 5 years after diagnosis. The relative risk of developing tinnitus as compared to siblings during and after childhood cancer therapy were reported up to 17.2 (95% CI 11.8-25.0) during therapy and up to 3.7 (95% CI 2.7-5.1) more than 5 years after diagnosis. Independent risk factors for tinnitus development included high dose cranial radiation and platinum based chemotherapy. CONCLUSION: The frequency of and risk to develop tinnitus seems to be higher in childhood cancer patients and survivors as compared to the normal population. Regular tinnitus screening before, during and after therapy with standardized questionnaires for early detection seems therefore reasonable in order to identify high-risk patients and eventually develop successful clinical preventive, supportive and management strategies.

Effects of the water-soluble fraction of a crude oil on estuarine meiofauna: A microcosm approach.

Although soluble hydrocarbons persist for only hours to days in aquatic environments, they potentially pose a high toxicity to aquatic biota. Here we investigate effects of the water-soluble fraction (WSF) of crude oil on estuarine meiofauna, with special focus on nematodes. Copepods and amphipods were the most sensitive taxa, disappearing almost completely within 3 weeks after exposure. In nematodes, we observed mostly sublethal short-term effects of WSF, such as changes in feeding-type composition and age structure. In the longer term (months), total nematode density and species composition were significantly affected, whereas different diversity indices did not exhibit significant responses. Deposit-feeding and predatory nematodes were the most affected feeding types. Nevertheless, sensitivity was species-specific, with sometimes opposing responses between even congeneric species. Our results demonstrate the need to assess WSF effects on communities at the species level and over time periods well exceeding the residence time of the WSF in the environment.

Adverse Effects of Fine-Particle Exposure on Joints and Their Surrounding Cells and Microenvironment.

Current understanding of the health risks and adverse effects upon exposure to fine particles is premised on the direct association of particles with target organs, particularly the lung; however, fine-particle exposure has also been found to have detrimental effects on sealed cavities distant to the portal-of-entry, such as joints. Moreover, the fundamental toxicological issues have been ascribed to the direct toxic mechanisms, in particular, oxidative stress and proinflammatory responses, without exploring the indirect mechanisms, such as compensated, adaptive, and secondary effects. In this Review, we recapitulate the current findings regarding the detrimental effects of fine-particle exposure on joints, the surrounding cells, and microenvironment, as well as their deteriorating impact on the progression of arthritis. We also elaborate the likely molecular mechanisms underlying the particle-induced detrimental influence on joints, not limited to direct toxicity, but also considering the other indirect mechanisms. Because of the similarities between fine air particles and engineered nanomaterials, we compare the toxicities of engineered nanomaterials to those of fine air particles. Arthritis and joint injuries are prevalent, particularly in the elderly population. Considering the severity of global exposure to fine particles and limited studies assessing the detrimental effects of fine-particle exposure on joints and arthritis, this Review aims to appeal to a broad interest and to promote more research efforts in this field.

Toxic effects and mechanism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on Lemna minor.

To investigate the toxic effect and mechanism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in aquatic plants, in vivo and in vitro exposure to BDE-47 were conducted. After 14-d exposure to 5-20 µg/L BDE-47, the growth of Lemna minor plants was significantly suppressed, and the chlorophyll and soluble protein contents in fronds markedly decreased. Accordingly, the photosynthetic efficiency (Fv/Fm, PI) decreased. When the thylakoid membranes isolated from healthy fronds was exposed to 5-20 mg/L BDE-47 directly in vitro for 1 h, the photosynthetic efficiency also decreased significantly. In both the in vitro (5-20 µg/L) and in vivo (5-20 mg/L) experiments, BDE-47 led to an increased plasma membrane permeability. Hence, we concluded that BDE-47 had a direct toxicity to photosynthetic membranes and plasma membranes. However, direct effects on the activities of peroxidase (POD), malate dehydrogenase (MDH) and nitroreductase (NR) were not observed by adding 5-20 mg/L BDE-47 into crude enzyme extracts. The malondialdehyde (MDA) and superoxide anion radical (O2-) contents in the BDE-47 treated fronds were higher than those in the control fronds, suggesting that L. minor can not effectively relieve reactive oxygen species (ROS). The data above indicates that BDE-47 is toxic to L. minor through acting directly on biomembranes, which induces the production of ROS and thus causes remarkable oxidative damage to cells.

Direct toxicity assessment - Methods, evaluation, interpretation.

Direct toxicity assessment (DTA) results provide the scale of the actual adverse effect of contaminated environmental samples. DTA results are used in environmental risk management of contaminated water, soil and waste, without explicitly translating the results into chemical concentration. The end points are the same as in environmental toxicology in general, i.e. inhibition rate, decrease in the growth rate or in yield and the 'no effect' or the 'lowest effect' measurement points of the sample dilution-response curve. The measurement unit cannot be a concentration, since the contaminants and their content in the sample is unknown. Thus toxicity is expressed as the sample proportion causing a certain scale of inhibition or no inhibition. Another option for characterizing the scale of toxicity of an environmental sample is equivalencing. Toxicity equivalencing represents an interpretation tool which enables toxicity of unknown mixtures of chemicals be converted into the concentration of an equivalently toxic reference substance. Toxicity equivalencing, (i.e. expressing the toxicity of unknown contaminants as the concentration of the reference) makes DTA results better understandable for non-ecotoxicologists and other professionals educated and thinking based on the chemical model. This paper describes and discusses the role, the principles, the methodology and the interpretation of direct toxicity assessment (DTA) with the aim to contribute to the understanding of the necessity to integrate DTA results into environmental management of contaminated soil and water. The paper also introduces the benefits of the toxicity equivalency method. The use of DTA is illustrated through two case studies. The first case study focuses on DTA of treated wastewater with the aim to characterize the treatment efficacy of a biological wastewater treatment plant by frequent bioassaying. The second case study applied DTA to investigate the cover layers of two bauxite residue (red mud) reservoirs. Based on the DTA results the necessary toxicity attenuation rate of the cover layers was estimated.

Risk assessment of an abandoned pyrite mine in Spain based on direct toxicity assays.

This research reports the risk assessment of an abandoned pyrite mine using direct toxicity assays of soil and groundwater samples taken at the site. The toxicity of As and heavy metals from mining soils to soil and aquatic organisms was studied using the Multispecies Soil System (MS-3) in soil columns. Ecotoxicological assessment was performed with soil samples diluted with a control soil at concentrations of 12.5, 25, 50 and 100% test soil/soil (w/w). In this way, changes in the mobility and bioavailability of soil contaminants due to changes in geochemical soil properties via soil dilution were studied. The toxicity of water samples was tested on algae and Daphnia magna. The assessment of the mining area indicated that the current presence of As and heavy metals at the site may cause injuries to soil and aquatic organisms in the entire research area. Moreover, this investigation demonstrated that changes in geochemical conditions can increase the availability of arsenic and, consequently, the environmental risk of these soils. A good correlation was not found between toxicity parameters and the concentrations of soil contaminants based on total and extracted element concentrations. This finding reinforces the usefulness of direct toxicity assays for evaluating environmental risk.