Fate and Characterization Factors of Nanoparticles in Seventeen Subcontinental Freshwaters: A Case Study on Copper Nanoparticles

Assessing human toxicity and ecotoxicity impacts of agricultural pesticide use in Iran based on the USEtox model

The human health and ecotoxicity impacts of agricultural pesticide use in Iran in 2022 were estimated. The impacts of agricultural pesticide use in Iran by pesticide, crop, and province were assessed based on the USEtox model in terms of disability-adjusted life year (DALY) for human health and potentially disappeared fraction of freshwater ecosystem species (PDF) for ecotoxicity. The annual mass of agricultural pesticide use in Iran in 2022 was 17,188 tons, consisting of herbicides (46.2 %), insecticides (30.0 %), and fungicides (23.8 %). The DALYs and DALY rate (per 100,000 people) of agricultural pesticide use in Iran were determined to be 25,140 and 29.4, respectively. The ecotoxicity impact of agricultural pesticide use in Iran was calculated to be 3.35 × 10+12 PDF m3 d. Over 79 % of the human health and ecotoxicity impacts of agricultural pesticide use were attributed to six pesticides (chlorpyrifos, deltamethrin, ethion, phosalone, thiodicarb, and abamectin) and eight crops (pistachio, apple, fig, vegetables, date, orange, wheat and barley, and cotton). While the contributions of the pesticides to the human health and ecotoxicity impact were not the same, chlorpyrifos ranked highest in both human health (28.8 %) and ecotoxicity (49.9 %) impacts. The highest provincial human health and ecotoxicity impacts of agricultural pesticide use were observed in Tehran (4,201 DALYs) and Fars (3.66 ×10+11 PDF m3 d), respectively. The provincial human health and ecotoxicity impacts were mainly driven by population and cropland area, respectively. Given the considerable human health and ecotoxicity impacts, developing national and provincial action plans for more sustainable use of pesticides in Iran is strongly recommended.

Safe nanomaterials: from their use, application, and disposal to regulations

Nanomaterials are structures with a wide range of applications in the medical, pharmaceutical, food, textile, and electronic industries, reaching more customers worldwide. As a relatively new technological field, the information about the associated risk of nanomaterials in environmental and human health must be addressed and consolidated to develop accurate legislations, frameworks, and guidelines to standardise their use in any field. This review aims to display and context the global applications of nanomaterials, their final disposal, as well as the perspective of the current efforts formulated by various countries (including Mexico and Latin American countries), international official departments and organisations directed to implement regulations on nanomaterials, nanotechnology, and nanoscience matters. In addition, the compiled information includes the tools, initiatives, and strategies to develop regulatory frameworks, such as life cycle assessments, risk assessments, technical tools, and biological models to evaluate their effects on living organisms. Finally, the authors point out the importance of implementing global regulations to promote nanotechnological research according to a precautionary principle focused on an environmental and health protection approach to ensure the use and application of nanotechnologies safely, and responsibly.

Assessment of microelement ecotoxicity in fen for ecological state monitoring

Wetlands, including bogs, fens, and swamps, play a crucial role in maintaining ecological balance by absorbing pollutants. They also conserve biodiversity and serve as breeding and migration sites for living organisms whose treated by pollutants entering to the wetland ecosystems. Pollutants entering wetland ecosystems can have detrimental effects on these important functions. The article introduces the method of toxicity assessment of microelements used in the environmental condition monitoring of the Ob River's floodplain fen (Tomsk Oblast, Russia). The impact of freshwater species (PAF m3day/kgemitted) is evaluated by calculating the Life Cycle Assessment Impact score for Be, V, Cr, Mn, Fe, Cu, Zn, As, Sr, Mo, Pb, Cd, Sb, Ba, and Tl at distances of 40, 100, and 160 m from the wastewater discharge site. The study considers the elemental composition and total volume of water from various areas within the research site for assessing freshwater ecotoxicity. 12 out of 15 investigated trace elements have the greatest impact on the freshwater system in the zone of 160 m from the site of anthropogenic impact on the water body. The sampling areas can be ranked based on their ∑IS value, with IS160 = 1.3E+11, followed by IS100 = 7.5E+10, and IS40 = 1.5E+10 [PAF m3day/kgemitted].

Tissue-specific toxic effects of nano-copper on zebrafish

Understanding the behavior and potential toxicity of copper nanoparticles (nano-Cu) in the aquatic environment is a primary way to assess their environmental risks. In this study, RNA-seq was performed on three different tissues (gills, intestines, and muscles) of zebrafish exposed to nano-Cu, to explore the potential toxic mechanism of nano-Cu on zebrafish. The results indicated that the toxic mechanism of nano-Cu on zebrafish was tissue-specific. Nano-Cu enables the CB1 receptor of the presynaptic membrane of gill cells to affect short-term synaptic plasticity or long-term synaptic changes (ECB-LTD) through DSI and DSE, causing dysfunction of intercellular signal transmission. Imbalance of de novo synthesis of UMP in intestinal cells and its transformation to UDP, UTP, uridine, and uracil, resulted in many functions involved in the pyrimidine metabolic pathway being blocked. Meanwhile, the toxicity of nano-Cu caused abnormal expression of RAD51 gene in muscle cells, which affects the repair of damaged DNA through Fanconi anemia and homologous recombination pathway, thus causing cell cycle disorder. These results provide insights for us to better understand the differences in toxicity of nano-Cu on zebrafish tissues and are helpful for a comprehensive assessment of nano-Cu's effects on aquatic organisms.

Emerging contaminants and their potential impacts on estuarine ecosystems: Are we aware of it?

Emerging contaminants (ECs) are becoming more prevalent in estuaries and constitute a danger to both human health and ecosystems. These pollutants can infiltrate the ecosystem and spread throughout the food chain. Because of the diversified sources and extensive human activities, estuaries are particularly susceptible to increased pollution levels. A thorough review on recent ECs (platinum group elements, pharmaceuticals and personal care products, pesticides, siloxanes, liquid crystal monomers, cationic surfactant, antibiotic resistance genes, and microplastics) in estuaries, including their incidence, detection levels, and toxic effects, was performed. The inclusion of studies from different regions highlights the global nature of this issue, with each location having its unique set of contaminants. The diverse range of contaminants detected in estuary samples worldwide underscores the intricacy of ECs. A significant drawback is the scarcity of research on the toxic mechanisms of ECs on estuarine organisms, the prospect of unidentified ECs, warrant research scopes.

UV-dependent freshwater effect factor of nanoscale titanium dioxide for future life cycle assessment application

Environmental impacts of nanoscale titanium dioxide (TiO₂ ) should be assessed throughout the lifetime of nanoparticles (NPs) to improve the state of knowledge of the overall sustainability. Life cycle assessment (LCA) has been previously recognized as a promising approach to systematically evaluating environmental impacts of NPs. As a result of their unique nanospecific properties, characterization factors (CF) were previously used for compensating the release and potential impacts of TiO₂ NPs. However, because TiO₂ NPs are known to generate reactive oxygen species and elicit toxicity to freshwater organisms, the lack of adequate UV-dependent effect factors (EFs) remains a major shortcoming when addressing their life cycle impacts. To complement the LCA of TiO₂ -NPs-enabled products under their specific applications, we recapitulated the freshwater toxicity of TiO₂ NPs and then modeled in USEtox to determine trophic level EF ranges under UV and non-UV exposure conditions. Results indicate that EFs derived for non-UV exposure were 52 (42.9-65) potentially affected fraction (PAF) m³ /kg, and combined toxicity data derived EFs were 70.1 (55.6-90.5) PAF m³ /kg. When considering only the UV-induced exposure condition, the modeled EF increased to 500 (333-712) PAF m³ /kg. Our work highlights that case-dependent EFs should be considered and applied to reflect more realistic ecological impacts and illustrate comprehensive life cycle environmental impacts for nanoenabled products. Integr Environ Assess Manag 2023;19:578-585. © 2022 SETAC.

Simulation of the Environmental Fate and Transformation of Nano Copper Oxide in a Freshwater Environment

Production of engineered nanomaterials (ENMs) has rapidly increased, yet uncertainty exists regarding the full extent of their environmental implications. This study investigates the fate, transformation, and speciation of nano copper oxide (nanoCuO) released into Lake Waccamaw, North Carolina, over 101 years. Using the Advanced Toxicant module of the Water Quality Analysis Simulation Program (WASP8), we assessed the accumulation and mass proportions of nanoCuO and Cu²⁺ (the product of nanoCuO's dissolution) in the water column and sediments. Our simulations suggest that when nanoCuO is released into Lake Waccamaw, the highest concentrations of both nanoCuO and Cu²⁺ are found in the surface sediments, followed by the subsurface sediments and the water column. Simulating different heteroaggregation attachment efficiencies of nanoCuO suggested that increases in attachment efficiency increased nanoCuO concentrations and mass proportions in the water column and sediments, while Cu²⁺ exhibited the opposite trends. After 101 years, most nanoCuO in the sediments was attached to particulate organic matter and clay particles at all attachment efficiencies, while low attachment efficiency slowed aggregate formation in the water column. Our results highlight the influence that heteroaggregation has on the behavior of nanoCuO inputs and suggest the potential for legacy contamination of nanoCuO and Cu²⁺ in sediments.

Life Cycle Assessment of Microplastics Reveals Their Greater Environmental Hazards than Mismanaged Polymer Waste Losses

Concern about microplastic pollution sourced from mismanaged plastic waste losses to drainage basins is growing but lacks relevant environmental impact analyses. Here, we reveal and compare the environmental hazards of aquatic macro- and microplastic debris through a holistic life cycle assessment approach. Compared to polymeric debris, microplastics, especially smaller than 10 μm, exhibit higher freshwater ecotoxicity enhanced by watersheds' high average depth and low water temperature. High microplastic concentration within drainage basins can also cause air pollution regarding particulate matter formation and photochemical ozone formation. The environmental drawbacks of plastic mismanagement are then demonstrated by showing that the microplastic formulation and removal in drinking water treatment plants can pose more than 7.44% of the total ecotoxicity effect from plastic wastes' (microplastics') whole life cycle. Specifically, these two life cycle stages can also cause more than 50% of the plastic wastes' life cycle ecotoxicity effect related to organic chemical emissions. Therefore, reducing environmentally harmful plastic losses through advanced plastic waste recycling, collection, and effective microplastic removal technologies needs future investigation.

Potential trade-off between water consumption and water quality: life cycle assessment of nonaqueous solvent dyeing

Fashion industry consumes over 60% of global fibers and attracts increasing attentions due to its environmentally polluting supply chain. In addition to natural fibers cultivation, wet processes of textile manufacturing are also important contributors to water-related impacts due to their large freshwater consumption and the production of chemicals containing wastewater. Despite of efforts made in improving efficiency of water use and wastewater treatment in textile industry, innovative 'water-free' technologies, such as nonaqueous dyeing technology using organic solvent, have been developed and demonstrated to reduce water consumption significantly. However, the potential impact on water quality by organic solvents induced in supply chain of this emerging technology remains unassessed, posing an unknown risk of its promotion. Hence, in the present study, a comprehensive life cycle assessment is applied to evaluate its full environmental impacts, including those on ecosystem and human health caused by decamethylcyclopentasiloxane (D5) as the solvent used. Further, the nonaqueous dyeing system is compared with traditional aqueous dyeing technology from both environmental and economic perspectives. Results indicate that nonaqueous dyeing system is advanced in most of environment categories except for abiotic depletion potential (ADP) and Ecotoxicity. However, scenarios analysis reveal that these findings are influenced by the loss fraction of D5 during the solvent recovery process. It is suggested that the loss fraction should be controlled below 2% o.w.f. for the nonaqueous dyeing technology to be advanced throughout all environmental categories. Nonaqueous D5 dyeing could reduce water consumption by 61.30%-79.95% and greenhouse gas emissions by 43.70% compared to the traditional system, delivering a promising contribution to China's 2060 carbon neutrality ambition. Sensitivity and uncertainty analyses are also conducted to investigate the effects of the key parameters (incl. inventory data and USEtox model inputs) and demonstrate the robustness of our assessment.

Life Cycle Assessment-Based Comparative Study between High-Yield and "Standard" Bottom-Up Procedures for the Fabrication of Carbon Dots

Carbon dots (CDs) are carbon-based nanomaterials with remarkable properties that can be produced from a wide variety of synthesis routes. Given that "standard" bottom-up procedures are typically associated with low synthesis yields, different authors have been trying to devise alternative high-yield fabrication strategies. However, there is a doubt if sustainability-wise, the latter should be really preferred to the former. Herein, we employed a Life Cycle Assessment (LCA) approach to compare and understand the environmental impacts of high-yield and "standard" bottom-up strategies, by applying different life cycle impact assessment (LCIA) methods. These routes were: (1) production of hydrochar, via the hydrothermal treatment of carbon precursors, and its alkaline peroxide treatment into high-yield CDs; (2) microwave treatment of carbon precursors doped with ethylenediamine; (3) and (6) thermal treatment of carbon precursor and urea; (4) hydrothermal treatment of carbon precursor and urea; (5) microwave treatment of carbon precursor and urea. For this LCA, four LCIA methods were used: ReCiPe, Greenhouse Gas Protocol, AWARE, and USEtox. Results identified CD-5 as the most sustainable synthesis in ReCiPe, Greenhouse Gas Protocol, and USEtox. On the other hand, in AWARE, the most sustainable synthesis was CD-1. It was possible to conclude that, in general, high-yield synthesis (CD-1) was not more sustainable than "standard" bottom-up synthesis, such as CD-5 and CD-6 (also with relatively high-yield). More importantly, high-yield synthesis (CD-1) did not generate much lower environmental impacts than "standard" approaches with low yields, which indicates that higher yields come with relevant environmental costs.

Safe-and-Sustainable-by-Design Framework Based on a Prospective Life Cycle Assessment: Lessons Learned from a Nano-Titanium Dioxide Case Study

Safe-and-sustainable-by-design (SSbD) is a concept that takes a systems approach by integrating safety, sustainability, and functionality throughout a product's the life cycle. This paper proposes a framework based on a prospective life cycle assessment for early safety and sustainability assessment. The framework's purpose is to identify environmental sustainability and toxicity hotspots early in the innovation process for future SSbD applicability. If this is impossible, key performance indicators are assessed. Environmental sustainability aspects, such as global warming potential (GWP) and cumulative energy demand (CED), and toxicity aspects, such as human toxicity potential and freshwater ecotoxicity potential, were assessed upon applying the framework on a case study. The case study regarded using nano-titanium dioxide (P25-TiO2) or a modified nano-coated version (Cu2O-coated/P25-TiO2) as photocatalysts to produce hydrogen from water using sunlight. Although there was a decrease in environmental impact (GWP and CED), the modified nano-coated version had a relatively higher level of human toxicity and freshwater eco-toxicity. For the presented case study, SSbD alternatives need to be considered that improve the photocatalytic activity but are not toxic to the environment. This case study illustrates the importance of performing an early safety and environmental sustainability assessment to avoid the development of toxic alternatives.

Integrative approach in a safe by design context combining risk, life cycle and socio-economic assessment for safer and sustainable nanomaterials

Moving towards safe and sustainable innovations is an international policy ambition. In the on-hand manuscript, a concept combining safe by design and sustainability was implemented through the integration of human and environmental risk assessment, life cycle assessment as well as an assessment of the economic viability. The result is a nested and iterative process in form of a decision tree that integrates these three elements in order to achieve sustainable, safe and competitive materials, products or services. This approach, embedded into the stage-gate-model for safe by design, allows to reduce the uncertainty related to the assessment of risks and impacts by improving the quality of the data collected along each stage. In the second part of the manuscript, the application is shown for a case study dealing with the application of nanoparticles for Li-Ion batteries. One of the general conclusions out of this case study is that data gaps are a key aspect in view of the reliability of the results.

Comparative life cycle assessment of high-yield synthesis routes for carbon dots

Carbon dots (CDs) are carbon-based nanomaterials with advantageous luminescent properties, making them promising alternatives to other molecular and nanosized fluorophores. However, the development of CDs is impaired by the low synthesis yield of standard fabrication strategies, making high-yield strategies essential. To help future studies to focus on cleaner production strategies, we have employed a Life Cycle Assessment (LCA) to compare and understand the environmental impacts of available routes for the high-yield synthesis of carbon dots. These routes were: (1) production of hydrochar, via hydrothermal treatment of carbon precursors, and its alkaline-peroxide treatment into high-yield carbon dots; (2) thermal treatment of carbon precursors mixed in a eutectic mixture of salts. Results show that the first synthesis route is associated with the lowest environmental impacts. This is attributed to the absence of the mixture of salts in the first synthesis route, which offsets its higher electricity consumption. Sensitivity analysis showed that the most critical parameter in the different synthetic strategies is the identity of the carbon precursor, with electricity being also relevant for the first synthesis route. Nevertheless, the use of some carbon precursors (as citric acid) with higher associated environmental impacts may be justified by their beneficial role in increasing the luminescent performance of carbon dots. Thus, the first synthesis route is indicated to be the most environmental benign and should be used as a basis in future studies aimed to the cleaner and high-yield production of carbon dots.

Guiding the design space for nanotechnology to advance sustainable crop production

The globally recognized need to advance more sustainable agriculture and food systems has motivated the emergence of transdisciplinary solutions, which include methodologies that utilize the properties of materials at the nanoscale to address extensive and inefficient resource use. Despite the promising prospects of these nanoscale materials, the potential for large-scale applications directly to the environment and to crops necessitates precautionary measures to avoid unintended consequences. Further, the effects of using engineered nanomaterials (ENMs) in agricultural practices cascade throughout their life cycle and include effects from upstream-embodied resources and emissions from ENM production as well as their potential downstream environmental implications. Building on decades-long research in ENM synthesis, biological and environmental interactions, fate, transport and transformation, there is the opportunity to inform the sustainable design of nano-enabled agrochemicals. Here we perform a screening-level analysis that considers the system-wide benefits and costs for opportunities in which ENMs can advance the sustainability of crop-based agriculture. These include their on-farm use as (1) soil amendments to offset nitrogen fertilizer inputs, (2) seed coatings to increase germination rates and (3) foliar sprays to enhance yields. In each analysis, the nano-enabled alternatives are compared against the current practice on the basis of performance and embodied energy. In addition to identifying the ENM compositions and application approaches with the greatest potential to sustainably advance crop production, we present a holistic, prospective, systems-based approach that promotes emerging alternatives that have net performance and environmental benefits.

Life Cycle Assessment of the Sustainability of Enhancing the Photodegradation Activity of TiO2 with Metal-Doping

While TiO2 nanoparticles have shown potential as photocatalysts in the degradation of organic contaminants, their inability to absorb efficiently visible light has limited their industrial application. One strategy for solving this problem is monodoping TiO2 photocatalysts with transition metals, which has worked in the degradation of several pollutants. However, it is not clear if this improvement is enough to offset the potential environmental impacts of adding metal ions to the synthesis of TiO2. Herein, we have used Life Cycle Assessment (LCA) to determine the sustainability of monodoping TiO2 with transition metals (Fe, Co, Mn and Ni, with a 1% weight ratio) to enhance the photocatalytic properties of the photocatalyst toward the degradation of Carbamazepine and Methyl Orange, under UV-A and visible light irradiation. We found that the addition of transition-metals has no significant effect on the environmental impacts associated with the synthesis of TiO2, when a weight-based functional unit was considered. However, when photocatalytic activity was considered, major differences were found. Thus, our results demonstrate that the sustainability of monodoping with different transition metals is solely determined by their ability to enhance (or not) the photocatalytic activity of TiO2. Our data also demonstrated that isopropyl alcohol constitutes a critical point in the synthesis of TiO2 photocatalysts, with ethanol being a potential substitute.

Evaluation of the Environmental Impact and Efficiency of N-Doping Strategies in the Synthesis of Carbon Dots

The efficiency and associated environmental impacts of different N-doping strategies of carbon dots (CDs) were evaluated. More specifically, N-doped CDs were prepared from citric acid via two main synthesis routes: Microwave-assisted hydrothermal treatment with addition of N-containing small organic molecules (urea and ethylenediamine (EDA)); and microwave-assisted solvothermal treatment in N-containing organic solvents (n,n-dimethylformamide (DMF), acetonitrile and pyridine). These syntheses produced CDs with similar blue emission. However, XPS analysis revealed that CDs synthesized via both hydrothermal routes presented a better N-doping efficiency (~15 at.%) than all three solvothermal-based strategies (0.6-7 at.%). However, from the former two hydrothermal strategies, only the one involving EDA as a nitrogen-source provided a non-negligible synthesis yield, which indicates that this should be the preferred strategy. This conclusion was supported by a subsequent life cycle assessment (LCA) study, which revealed that this strategy is clearly the most sustainable one from all five studied synthesis routes.

The Toxicity of Nanoparticles to Organisms in Freshwater

Nanotechnology is a rapidly growing industry yielding many benefits to society. However, aquatic environments are at risk as increasing amounts of nanoparticles (NPs) are contaminating waterbodies causing adverse effects on aquatic organisms. In this review, the impacts of environmental exposure to NPs, the influence of the physicochemical characteristics of NPs and the surrounding environment on toxicity and mechanisms of toxicity together with NP bioaccumulation and trophic transfer are assessed with a focus on their impacts on bacteria, algae and daphnids. We identify several gaps which need urgent attention in order to make sound decisions to protect the environment. These include uncertainty in both estimated and measured environmental concentrations of NPs for reliable risk assessment and for regulating the NP industry. In addition toxicity tests and risk assessment methodologies specific to NPs are still at the research and development stage. Also conflicting and inconsistent results on physicochemical characteristics and the fate and transport of NPs in the environment suggest the need for further research. Finally, improved understanding of the mechanisms of NP toxicity is crucial in risk assessment of NPs, since conventional toxicity tests may not reflect the risks associated with NPs. Behavioural effects may be more sensitive and would be efficient in certain situations compared with conventional toxicity tests due to low NP concentrations in field conditions. However, the development of such tests is still lacking, and further research is recommended.

Interaction of zero valent copper nanoparticles with algal cells under simulated natural conditions: Particle dissolution kinetics, uptake and heteroaggregation

Some metal-based engineered nanoparticles (ENPs) undergo fast dissolution and/or aggregation when they are released in the environment. The underlying processes are controlled by psychochemical/biological parameters of the environment and the properties of the particles. In this study, we investigated the interaction between algal cells and zero valent copper nanoparticles (Cu⁰-ENPs) to elucidate how the cells influence the dissolution and aggregation kinetics of the particles and how these kinetics influence the cellular uptake of Cu. Our finding showed that the concentration of dissolved Cu ([Cu]_dissolved) in the supernatant of the culture media without algal cells was higher than the [Cu]_dissolved in the media with algal cells. In the absence of the cells, dissolved organic matter (DOC) increased the dissolution of the particle due to increasing the stability of the particles against aggregation, thus increasing the available surface area. In the presence of algae, Cu⁰-ENPs heteroaggregated with the cells. Thus, the available surface area decreased over time and this resulted in a low dissolution rate of the particles. The DOC corona on the surface of the particles increased the heteroaggregation of the particles with the cells and decreases the uptake of the particles. Our findings showed that microorganisms influence the fate of ENPs in the environment, and they do so by modifying the dissolution and aggregation kinetics of the Cu⁰-ENPs.

Acute toxic effects caused by the co-exposure of nanoparticles of ZnO and Cu in rainbow trout

The toxic effects produced by the co-exposure to low- and non-toxic concentrations of zinc oxide (ZnONPs) and copper nanoparticles (CuNPs) was assessed in rainbow trout following the OECD Test Guideline 203. Four groups of trouts were exposed for 96 h to a range of concentrations (0.0425-0.34 mg/L) of CuNPs (50 nm) in combination with a fixed non-toxic concentration (1.25 mg/L) of ZnONPs (25 nm) determined from an independent concentration-response study. One additional group was exposed to the highest concentration of CuNPs alone. Behaviour and mortality were observed during the experiment. After 96 h exposure, accumulated levels of Cu and Zn in the fish were measured by ICP-MS and ICP-OES, respectively. The induction of oxidative stress in liver and gills was evaluated by the glutathione-S-transferase (GST) activity and the reduced glutathione (GSH) / oxidized glutathione (GSSG) ratio. The ethoxyresorufin-O-deethylase (EROD) activity was also assessed. The results showed that CuNPs at the highest tested concentration do not cause acute toxicity, whereas exposure to all mixtures caused mortality, which was inversely proportional to the concentration of CuNPs (from 28% to 86% survival). Accumulated levels of Cu and Zn in the fish increased with the increasing concentrations of CuNPs, suggesting that the presence of CuNPs favours the entry of Zn. In general, the GST activity increased significantly in the gills of co-exposed groups, whereas the GSH/GSSG ratio was altered in the liver. The EROD activity was not modified. In conclusion, the co-exposure to these NPs potentiates their toxicity, observing an alteration of the GST activity and GSH/GSSG ratio in gill and liver, which was more pronounced at the lowest concentration of CuNPs. The lower toxic effect observed with the highest concentrations of CuNPs coincides with a greater internalization of Zn.

Copper release and transformation following natural weathering of nano-enabled pressure-treated lumber

Commercially available lumber, pressure-treated with micronized copper azole (MCA), has largely replaced other inorganic biocides for residential wood treatment in the USA, yet little is known about how different outdoor environmental conditions impact the release of ionic, nano-scale, or larger (micron-scale) copper from this product. Therefore, we weathered pressure treated lumber for 18 months in five different climates across the continental United States. Copper release was quantified every month and local weather conditions were recorded continuously to determine the extent to which local climate regulated the release of copper from this nano-enabled product during its use phase. Two distinct release trends were observed: In cooler, wetter climates release occurred primarily during the first few months of weathering, as the result of copper leaching from surface/near-surface areas. In warmer, drier climates, less copper was initially released due to limited precipitation. However, as the wood dried and cracked, the exposed copper-bearing surface area increased, leading to increased copper release later in the product lifetime. Single-particle-ICP-MS results from laboratory prepared MCA-wood leachate solutions indicated that a) the predominant form of released copper passed through a filter smaller than 0.45 micrometers and b) released particles were largely resistant to dissolution over the course of 6 wks. Toxicity Characteristic Leaching Procedure (TCLP) testing was conducted on nonweathered and weathered MCA-wood samples to simulate landfill conditions during their end-of-life (EoL) phase and revealed that MCA wood released <10% of initially embedded copper. Findings from this study provide data necessary to complete a more comprehensive evaluation of the environmental and human health impacts introduced through release of copper from pressure treated lumber utilizing life cycle assessment (LCA).

Physiological and transcriptomic analyses reveal CuO nanoparticle inhibition of anabolic and catabolic activities of sulfate-reducing bacterium

The widespread use of CuO nanoparticles (NPs) results in their continuous release into the environment, which could pose risks to public health and to microbial ecosystems. Following consumption, NPs will initially enter into sewer systems and interact with and potentially influence sewer microbial communities. An understanding of the response of microbes in sewers, particularly sulfate-reducing bacteria (SRB), to the CuO NPs induced stress is important as hydrogen sulfide produced by SRB can cause sewer corrosion and odour emissions. In this study, we elucidated how the anabolic and catabolic processes of a model SRB, Desulfovibrio vulgaris Hidenborough (D. vulgaris), respond to CuO NPs. Physiological analyses indicated that the exposure of the culture to CuO NPs at elevated concentrations (>50 mg/L) inhibited both its anabolic and catabolic activities, as revealed by lowered cell proliferation and sulfate reduction rate. The antibacterial effects of CuO NPs were mainly attributed to the overproduction of reactive oxygen species. Transcriptomic analysis indicated that genes encoding for flagellar assembly and some genes involved in electron transfer and respiration were down-regulated, while genes for the ferric uptake regulator (Fur) were up-regulated. Moreover, the CuO NPs exposure significantly up-regulated genes involved in protein synthesis and ATP synthesis. These results suggest that CuO NPs inhibited energy conversion, cell mobility, and iron starvation to D. vulgaris. Meanwhile, D. vulgaris attempted to respond to the stress of CuO NPs by increasing protein and ATP synthesis. These findings offer new insights into the bacterial-nanoparticles interaction at the transcriptional level, and advance our understanding of impacts of CuO NPs on SRB in the environment.

Dynamic probabilistic material flow analysis of nano-SiO2, nano iron oxides, nano-CeO2, nano-Al2O3, and quantum dots in seven European regions

Static environmental exposure assessment models based on material flow analysis (MFA) have previously been used to estimate flows of engineered nanomaterials (ENMs) to the environment. However, such models do not account for changes in the system behavior over time. Dynamic MFA used in this study includes the time-dependent development of the modelling system by considering accumulation of ENMs in stocks and the environment, and the dynamic release of ENMs from nano-products. In addition, this study also included regional variations in population, waste management systems, and environmental compartments, which subsequently influence the environmental release and concentrations of ENMs. We have estimated the flows and release concentrations of nano-SiO₂, nano-iron oxides, nano-CeO₂, nano-Al₂O₃, and quantum dots in the EU and six geographical sub-regions in Europe (Central Europe, Northern Europe, Southern Europe, Eastern Europe, South-eastern Europe, and Switzerland). The model predicts that a large amount of ENMs are accumulated in stocks (not considering further transformation). For example, in the EU 2040 Mt of nano-SiO₂ are stored in the in-use stock, 80,400 tonnes have been accumulated in sediments and 65,600 tonnes in natural and urban soil from 1990 to 2014. The magnitude of flows in waste management processes in different regions varies because of differences in waste handling. For example, concentrations in landfilled waste are lowest in South-eastern Europe due to dilution by the high amount of landfilled waste in the region. The flows predicted in this work can serve as improved input data for mechanistic environmental fate models and risk assessment studies compared to previous estimates using static models.

Influence of humic acid and dihydroxy benzoic acid on the agglomeration, adsorption, sedimentation and dissolution of copper, manganese, aluminum and silica nanoparticles - A tentative exposure scenario

This work focuses on kinetic aspects of stability, mobility, and dissolution of bare Cu, Al and Mn, and SiO₂ NPs in synthetic freshwater (FW) with and without the presence of natural organic matter (NOM). This includes elucidation of particle and surface interactions, metal dissolution kinetics, and speciation predictions of released metals in solution. Dihydroxy benzoic acid (DHBA) and humic acid adsorbed rapidly on all metal NPs (<1 min) via multiple surface coordinations, followed in general by rapid agglomeration and concomitant sedimentation for a large fraction of the particles. In contrast, NOM did not induce agglomeration of the SiO₂ NPs during the test duration (21 days). DHBA in concentrations of 0.1 and 1 mM was unable to stabilize the metal NPs for time periods longer than 6 h, whereas humic acid, at certain concentrations (20 mg/L) was more efficient (>24 h). The presence of NOM increased the amount of released metals into solution, in particular for Al and Cu, whereas the effect for Mn was minor. At least 10% of the particle mass was dissolved within 24 h and remained in solution for the metal NPs in the presence of NOM. Speciation modeling revealed that released Al and Cu predominantly formed complexes with NOM, whereas less complexation was seen for Mn. The results imply that potentially dispersed NPs of Cu, Al and Mn readily dissolve or sediment close to the source in freshwater of low salinity, whereas SiO₂ NPs are more stable and therefore more mobile in solution.

The effect of nanoparticles and humic acid on technology critical element concentrations in aqueous solutions with soil and sand

As a consequence of their growing use in electronic and industrial products, increasing amounts of technology critical elements (TCEs) are being released to the environment. Currently little is known about the fate of many of these elements. Initial research on their potential environmental impact identifies TCEs as emerging contaminants. TCE movement in the environment is often governed by water systems. Research on "natural" waters so far demonstrates that TCEs tend to be associated with suspended particulate matter (SPM), which influences TCE aqueous concentrations (here: concentration of TCEs in dissolved form and attached to SPM) and transport. However, the relative potential of different types of SPM to interact with TCEs is unknown. Here we examine the potential of various types of particulate matter, namely different nanoparticles (NPs; Al₂O_3, SiO₂, CeO₂, ZnO, montmorillonite, Ag, Au and carbon dots) and humic acid (HA), to impact TCE aqueous concentrations in aqueous solutions with soil and sand, and thus influence TCE transport in soil-water environments. We show that a combination of NPs and HA, and not NPs or HA individually, increases the aqueous concentrations of TCEs in soil solutions, for all tested NPs regardless of their type. TCEs retained on SPM, however, settle with time. In solutions with sand, HA alone is as influential as NPs+HA in keeping TCEs in the aqueous phase. Among NPs, Ag-NPs and Au-NPs demonstrate the highest potential for TCE transport. These results suggest that in natural soil-water environments, once TCEs are retained by soil, their partitioning to the aqueous phase by through-flowing water is unlikely. However, if TCEs are introduced to soil-water environments as part of solutions rich in NPs and HA, it is likely that NP and HA combinations can increase TCE stability in the aqueous phase and prevent their retention on soil and sand, thus facilitating TCE transport.

Life Cycle Assessment and Release Studies for 15 Nanosilver-Enabled Consumer Products: Investigating Hotspots and Patterns of Contribution

Increasing use of silver nanoparticles (AgNPs) in consumer products as antimicrobial agents has prompted extensive research toward the evaluation of their potential release to the environment and subsequent ecotoxicity to aquatic organisms. It has also been shown that AgNPs can pose significant burdens to the environment from life cycle emissions associated with their production, but these impacts must be considered in the context of actual products that contain nanosilver. Here, a cradle-to-gate life cycle assessment for the production of 15 different AgNP-enabled consumer products was performed, coupled with release studies of those same products, thus providing a consistent analytical platform for investigation of potential nanosilver impacts across a range of product types and concentrations. Environmental burdens were assessed over multiple impact categories defined by the United States Environmental Protection Agency's Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI 2.1) method. Depending on the product composition and silver loading, the contribution of AgNP synthesis to the overall impacts was seen to vary over a wide range from 1% to 99%. Release studies found that solid polymeric samples lost more silver during wash compared to fibrous materials. Estimates of direct ecotoxicity impacts of AgNP releases from those products with the highest leaching rates resulted in lower impact levels compared to cradle-to-gate ecotoxicity from production for those products. Considering both cradle-to-gate production impacts and nanoparticle release studies, in conjunction with estimates of life cycle environmental and health benefits of nanoparticle incorporation, can inform sustainable nanoenabled product design.

Development of Comparative Toxicity Potentials of TiO2 Nanoparticles for Use in Life Cycle Assessment

Studies have shown that releases of nanoparticles may take place through the life cycle of products embedding nanomaterials, thus resulting in potential impacts on ecosystems and human health. While several life cycle assessment (LCA) studies have assessed such products, only a few of them have quantitatively addressed the toxic impacts caused by released nanoparticles, thus leading to potential biases in their conclusions. Here, we address this gap and aim to provide a framework for calculating characterization factors or comparative toxicity potentials (CTP) for nanoparticles and derive CTP values for TiO₂ nanoparticles (TiO₂-NP) for use in LCA. We adapted the USEtox 2.0 consensus model to integrate the SimpleBox4Nano fate model, and we populated the resulting model with TiO₂-NP specific data. We thus calculated CTP values for TiO₂ nanoparticles for air, water, and soil emission compartments for freshwater ecotoxicity and human toxicity, both cancer effects and noncancer effects. Our results appeared plausible after benchmarking with CTPs for other nanoparticles and substances present in the USEtox database, while large differences were observed with CTP values for TiO₂ nanoparticles published in earlier studies. Assumptions, which were performed in those previous studies because of lack of data and knowledge at the time they were made, primarily explain such discrepancies. For future assessment of potential toxic impacts of TiO₂ nanoparticles in LCA studies, we therefore recommend the use of our calculated CTP.