Analysis of currently available data for characterising the risk of engineered nanomaterials to the environment and human health--lessons learned from four case studies

Predicting environmental concentrations of nanomaterials for exposure assessment - a review

There have been major advances in the science to predict the likely environmental concentrations of nanomaterials, which is a key component of exposure and subsequent risk assessment. Considerable progress has been since the first Material Flow Analyses (MFAs) in 2008, which were based on very limited information, to more refined current tools that take into account engineered nanoparticle (ENP) size distribution, form, dynamic release, and better-informed release factors. These MFAs provide input for all environmental fate models (EFMs), that generate estimates of particle flows and concentrations in various environmental compartments. While MFA models provide valuable information on the magnitude of ENP release, they do not account for fate processes, such as homo- and heteroaggregation, transformations, dissolution, or corona formation. EFMs account for these processes in differing degrees. EFMs can be divided into multimedia compartment models (e.g., atmosphere, waterbodies and their sediments, soils in various landuses), of which there are currently a handful with varying degrees of complexity and process representation, and spatially-resolved watershed models which focus on the water and sediment compartments. Multimedia models have particular applications for considering predicted environmental concentrations (PECs) in particular regions, or for developing generic "fate factors" (i.e., overall persistence in a given compartment) for life-cycle assessment. Watershed models can track transport and eventual fate of emissions into a flowing river, from multiple sources along the waterway course, providing spatially and temporally resolved PECs. Both types of EFMs can be run with either continuous sources of emissions and environmental conditions, or with dynamic emissions (e.g., temporally varying for example as a new nanomaterial is introduced to the market, or with seasonal applications), to better understand the situations that may lead to peak PECs that are more likely to result in exceedance of a toxicological threshold. In addition, bioaccumulation models have been developed to predict the internal concentrations that may accumulate in exposed organisms, based on the PECs from EFMs. The main challenge for MFA and EFMs is a full validation against observed data. To date there have been no field studies that can provide the kind of dataset(s) needed for a true validation of the PECs. While EFMs have been evaluated against a few observations in a small number of locations, with results that indicate they are in the right order of magnitude, there is a great need for field data. Another major challenge is the input data for the MFAs, which depend on market data to estimate the production of ENPs. The current information has major gaps and large uncertainties. There is also a lack of robust analytical techniques for quantifying ENP properties in complex matrices; machine learning may be able to fill this gap. Nevertheless, there has been major progress in the tools for generating PECs. With the emergence of nano- and microplastics as a leading environmental concern, some EFMs have been adapted to these materials. However, caution is needed, since most nano- and microplastics are not engineered, therefore their characteristics are difficult to generalize, and there are new fate and transport processes to consider.

Single-cell ICP-MS for studying the association of inorganic nanoparticles with cell lines derived from aquaculture species

The current research deals with the use of single-cell inductively coupled plasma-mass spectrometry (scICP-MS) for the assessment of titanium dioxide nanoparticle (TiO2 NP) and silver nanoparticle (Ag NP) associations in cell lines derived from aquaculture species (sea bass, sea bream, and clams). The optimization studies have considered the avoidance of high dissolved background, multi-cell peak coincidence, and possible spectral interferences. Optimum operating conditions were found when using a dwell time of 50 μs for silver and 100 μs for titanium. The assessment of associated TiO2 NPs by scICP-MS required the use of ammonia as a reaction gas (flow rate at 0.75 mL min-1) for interference-free titanium determinations (measurements at an m/z ratio of 131 from the 48Ti(NH)(NH3)4 adduct). The influence of other parameters such as the number of washing cycles and the cell concentration on accurate determinations by scICP-MS was also fully investigated. Cell exposure trials were performed using PVP-Ag NPs (15 and 100 nm, nominal diameter) and citrate-TiO2 NPs (5, 25, and 45 nm, nominal diameter) at nominal concentrations of 10 and 50 μg mL-1 for citrate-TiO2 NPs and 5.0 and 50 μg mL-1 for PVP-Ag NPs. Results have shown that citrate-TiO2 NPs interact with the outer cell membranes, being quite low in the number of citrate-TiO2 NPs that enters the cells (the high degree of aggregation is the main factor which leads to the aggregates being in the extracellular medium). In contrast, PVP-Ag NPs have been found to enter the cells.

Global analysis of the perturbation effects of metal-based nanoparticles on soil nitrogen cycling

Although studies have investigated the effects of metal-based nanoparticles (MNPs) on soil biogeochemical processes, the results obtained thus far are highly variable. Moreover, we do not yet understand how the impact of MNPs is affected by experimental design and environmental conditions. Herein, we conducted a global analysis to synthesize the effects of MNPs on 17 variables associated with soil nitrogen (N) cycling from 62 studies. Our results showed that MNPs generally exerted inhibitory effects on N-cycling process rates, N-related enzyme activities, and microbial variables. The response of soil N cycling varied with MNP type, and exposure dose was the most decisive factor for the variations in the responses of N-cycling process rates and enzyme activities. Notably, Ag/Ag2 S and CuO had dose-dependent inhibitory effects on ammonia oxidation rates, while CuO and Zn/ZnO showed hormetic effects on nitrification and denitrification rates, respectively. Other experimental design factors (e.g., MNP size and exposure duration) also regulated the effect of MNPs on soil N cycling, and specific MNPs, such as Ag/Ag2 S, exerted stronger effects during long-term (>28 days) exposure. Environmental conditions, including soil pH, organic carbon, texture, and presence/absence of plants, significantly influenced MNP toxicity. For instance, the effects of Ag/Ag2 S on the ammonia oxidation rate and the activity of leucine aminopeptidase were more potent in acid (pH <6), organic matter-limited (organic carbon content ≤10 g kg-1 ), and coarser soils. Overall, these results provide new insights into the general mechanisms by which MNPs alter soil N processes in different environments and underscore the urgent need to perform multivariate and long-term in situ trials in simulated natural environments.

Screening Risk Assessment at the Production and Use Stage of Carbon Nanomaterials Generated in Hydrogen Manufacture by Methane Decomposition

We performed a screening evaluation of the human health risk posed by nanocarbon materials at the lifecycle stages of manufacturing and the use of the solid carbon generated in hydrogen manufacture by methane decomposition. We first estimated the atmospheric emission volumes of the solid carbon produced by small-, medium-, and large-scale hydrogen manufacturing plants. We then estimated the atmospheric emission due to tire wear, which largely contributes to the emission of solid carbon usage. Next, we estimated the atmospheric concentration of solid carbon in an atmospheric simulation using the METI–LIS model, which estimates the atmospheric distribution of a pollutant’s concentration near methane decomposition factories. We also used the AIST–ADMER model that estimated the regional atmospheric distributions around central Tokyo, where the traffic volume is the highest nationally. Finally, we performed a screening evaluation of human health risk in the surrounding areas, considering the permissible exposure concentrations of solid carbon. Our study identified no risk concerns at small- and medium-scale factory locations equipped with high-efficiency particulate air (HEPA) filtration facilities. At large-scale factories installed with HEPA filters, these emissions likely remain within the factory site. Furthermore, we determined that emissions from tire wear pose no risk to human health. The surroundings of small- and medium-scale factory sites installed with HEPA filters posed no risk to human health.

Public Awareness of Nanotechnology and Its Implications for Health in Jordan

Nanotechnology is often described as an emerging technology, holding promise for a diverse range of fields. Public awareness may have a strong impact on public acceptance of nano-technology and its various implications. In Jordan, nano-education has only been introduced recently into universities and it is offered to students of pharmacy, engineering, biomedical sciences, and agriculture. However, there is no data available on nanotechnology awareness among the public in Jordan. Therefore, we conducted this study to evaluate Jordanian public awareness and concern about nanotechnology, nanomaterials, and nanoproducts and its implications for health related applications of nanotechnology. An online survey was developed consisting of 15 questions and separated into three domains. The study findings show that more than half of the respondents have a very low awareness with regards to nanotechnology and its various implications. Additionally, respondents show interest to learn more about nanotechnology and its implications, preferring several sources of information such as media, universities and research institutions.

Occupational Exposure to Ultrafine Particles in Metal Additive Manufacturing: A Qualitative and Quantitative Risk Assessment

Ultrafine particles (UFPs) can be released unintentionally during metal additive manufacturing (AM). Experts agree on the urgent need to increase the knowledge of the emerging risk of exposure to nanoparticles, although different points of view have arisen on how to do so. This article presents a case study conducted on a metal AM facility, focused on studying the exposure to incidental metallic UFP. It intends to serve as a pilot study on the application of different methodologies to manage this occupational risk, using qualitative and quantitative approaches that have been used to study exposure to engineered nanoparticles. Quantitative data were collected using a condensation particle counter (CPC), showing the maximum particle number concentration in manual cleaning tasks. Additionally, scanning electron microscopy (SEM) and energy dispersive X-ray analyzer (EDS) measurements were performed, showing no significant change in the particles’ chemical composition, size, or surface (rugosity) after printing. A qualitative approach was fulfilled using Control Banding Nanotool 2.0, which revealed different risk bands depending on the tasks performed. This article culminates in a critical analysis regarding the application of these two approaches in order to manage the occupational risk of exposure to incidental nanoparticles, raising the potential of combining both.

Ecotoxicological effects of dietary titanium dioxide nanoparticles on metabolic and biochemical parameters of model organism Galleria mellonella (Lepidoptera: Pyralidae)

Nanoparticles (NPs) are now being used in many industrial activities, such as mining, paint and glass industries. The frequent industrial use of NPs contributes to environmental pollution and may cause cellular and oxidative damage in native organisms. In this study, the toxic effects of titanium dioxide nanoparticles (TiO₂ NPs) were investigated using Galleria mellonella larvae as a model insect species. Alterations in cell damage indicators, such as alanine transferase, aspartate transferase, lactate dehydrogenase, non-enzymatic antioxidants and biochemical parameters, were determined in the hemolymph of G. mellonella larvae exposed to TiO₂ NPs at different concentrations (5, 50, 250 and 1250 μg/mL) in their diets. TiO₂ NPs caused concentration-dependent cellular damage in the hemolymph of G. mellonella larvae and increased the levels of the non-enzymatic antioxidants uric acid and bilirubin. In addition, total protein in hemolymph significantly decreased at the highest concentration (1250 μg/mL) of TiO₂ NPs. Level of the urea increased at the highest concentration (1250 μg/mL) of TiO₂ NPs, whereas the amount of glucose was not affected. These findings demonstrated that TiO₂ NPs caused concentration-dependent toxic effects on G. mellonella larvae.

Antimicrobial Properties of Food Nanopackaging: A New Focus on Foodborne Pathogens

Food products contaminated by foodborne pathogens (bacteria, parasites, and viruses) cause foodborne diseases. Today, great efforts are being allocated to the development of novel and effective agents against food pathogenic microorganisms. These efforts even might have a possible future effect in coronavirus disease 2019 (COVID-19) pandemic. Nanotechnology introduces a novel food packaging technology that creates and uses nanomaterials with novel physiochemical and antimicrobial properties. It could utilize preservatives and antimicrobials to extend the food shelf life within the package. Utilizing the antimicrobial nanomaterials into food packaging compounds typically involves incorporation of antimicrobial inorganic nanoparticles such as metals [Silver (Ag), Copper (Cu), Gold (Au)], and metal oxides [Titanium dioxide (TiO2), Silicon oxide (SiO2), Zinc oxide (ZnO)]. Alternatively, intelligent food packaging has been explored for recognition of spoilage and pathogenic microorganisms. This review paper focused on antimicrobial aspects of nanopackaging and presented an overview of antibacterial properties of inorganic nanoparticles. This article also provides information on food safety during COVID-19 pandemic.

Cellular and Molecular Targeted Drug Delivery in Central Nervous System Cancers: Advances in Targeting Strategies

Central nervous system (CNS) cancers are among the most common and treatment-resistant diseases. The main reason for the low treatment efficiency of the disorders is the barriers against targeted delivery of anticancer agents to the site of interest, including the blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB). BBB is a strong biological barrier separating circulating blood from brain extracellular fluid that selectively and actively prevents cytotoxic agents and majority of anticancer drugs from entering the brain. BBB and BBTB are the major impediments against targeted drug delivery into CNS tumors. Nanotechnology and its allied modalities offer interesting and effective delivery strategies to transport drugs across BBB to reach brain tissue. Integrating anticancer drugs into different nanocarriers improves the delivery performance of the resultant compounds across BBB. Surface engineering of nanovehicles using specific ligands, antibodies and proteins enhances the BBB crossing efficacy as well as selective and specific targeting to the target cancerous tissues in CNS tumors. Multifunctional nanoparticles (NPs) have brought revolutionary advances in targeted drug delivery to brain tumors. This study reviews the main anatomical, physiological and biological features of BBB and BBTB in drug delivery and the recent advances in targeting strategies in NPs-based drug delivery for CNS tumors. Moreover, we discuss advances in using specific ligands, antibodies, and surface proteins for designing and engineering of nanocarriers for targeted delivery of anticancer drugs to CNS tumors. Finally, the current clinical applications and the perspectives in the targeted delivery of therapeutic molecules and genes to CNS tumors are discussed.

Influence of titanium dioxide nanoparticles on bioaccumulation, antioxidant defense and immune system of Galleria mellonella L

Nanomaterials of different sizes and diameters are frequently used in various industrial areas, due to the rapid development of nanotechnology. Hence, it leads to toxic effects on the environment and non-target organisms, and adverse effects such as oxidative stress and membrane damage in cells and tissues are occurred. Some biomarkers such as the accumulation of intermediate products, detoxification of the immune system, or xenobiotic are used in the detection of toxic effects of exogenous substances in living organisms. In this study, the effects on catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione-s-transferase (GST) enzyme activities to determine the toxic effects of TiO₂ NPs on antioxidant defense system, acetylcholinesterase (AChE) activity to determine their neurotoxic effects, and total hemocyte count (THC) to determine their effect on the immune system were investigated in model organism Galleria mellonella larvae. It was determined that major amounts of Ti were mostly eliminated through the Malpighian tubules. Moreover, TiO₂ NPs in different concentrations caused the formation of reactive oxygen species in G. mellonella and lead to an increase in antioxidant enzymes. Decreases were found in THC due to the TiO₂ NP application. As a result, it was concluded that TiO₂ NPs caused accumulation in tissues of the model organism G. mellonella, resulting in oxidative stress and has adverse effects on the immune system.

Antifungal Nano-Therapy in Veterinary Medicine: Current Status and Future Prospects

The global recognition for the potential of nanoproducts and processes in human biomedicine has given impetus for the development of novel strategies for rapid, reliable, and proficient diagnosis, prevention, and control of animal diseases. Nanomaterials exhibit significant antifungal and antimycotoxin activities against mycosis and mycotoxicosis disorders in animals, as evidenced through reports published over the recent decade and more. These nanoantifungals can be potentially utilized for the development of a variety of products of pharmaceutical and biomedical significance including the nano-scale vaccines, adjuvants, anticancer and gene therapy systems, farm disinfectants, animal husbandry, and nutritional products. This review will provide details on the therapeutic and preventative aspects of nanoantifungals against diverse fungal and mycotoxin-related diseases in animals. The predominant mechanisms of action of these nanoantifungals and their potential as antifungal and cytotoxicity-causing agents will also be illustrated. Also, the other theragnostic applications of nanoantifungals in veterinary medicine will be identified.

Impacts of Titanium Dioxide Nanoparticles on Serum Parameters and Enzyme Activities of Clarias gariepinus

Impacts of titanium dioxide nanoparticles (TiO₂ NPs) on serum glucose, albumin, total protein, cholesterol, triglyceride, sodium (Na⁺), potassium (K⁺), and chloride ion (Cl^-) levels and serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and cholinesterase (ChE) activities of Clarias gariepinus were determined after exposing the fish to 1, 5 and 10 mg/L titanium applied as TiO₂ over 1, 4 and 7 days. No mortality was observed during the experiments. Serum glucose and albumin levels increased while serum total protein, cholesterol and triglyceride levels decreased compared to control at the end of the 7th day. Serum Na⁺, K⁺ and Cl^- levels of C. gariepinus decreased after 7 days of exposure to 10 mg/L TiO₂ NPs. ChE activity decreased and AST, ALT, ALP activities increased at all exposure concentrations and LDH activities increased compared to control after 4 and 7 days of exposure to TiO₂ NPs in C. gariepinus.

Testing the bioaccumulation potential of manufactured nanomaterials in the freshwater amphipod Hyalella azteca

Standardized experimental approaches for the quantification of the bioaccumulation potential of nanomaterials in general and in (benthic) invertebrates in particular are currently lacking. We examined the suitability of the benthic freshwater amphipod Hyalella azteca for the examination of the bioaccumulation potential of nanomaterials. A flow-through test system that allows the generation of bioconcentration and biomagnification factors was applied. The feasibility of the system was confirmed in a 2-lab comparison study. By carrying out bioconcentration and biomagnification studies with gold, titanium dioxide and silver nanoparticles as well as dissolved silver (AgNO₃) we were able to assess the bioaccumulation potential of different types of nanomaterials and their exposure pathways. For this, the animals were examined for their total metal body burden using inductively coupled mass spectroscopy (ICP-MS) and for the presence of nanoparticulate burdens using single-particle ICP-MS. The role of released ions was highlighted as being very important for the bioavailability and bioaccumulation of metals from nanoparticles for both examined uptake paths examined (bioconcentration and biomagnification). In 2018 a tiered testing strategy for engineered nanomaterials was proposed by Handy et al. that may allow a waiver of bioaccumulation fish studies using inter alia invertebrates. Data gained in studies carried out with invertebrates like the developed Hyalella azteca test may be included in this proposed tiered testing strategy.

Quantification of carboxyl-functionalized multiwall carbon nanotubes in plant tissues with programmed thermal analysis

In this study, carboxyl functionalized multiwall carbon nanotubes (c-MWCNTs) in plant (lettuce [Lactuca sativa Bionda Ricciolina]) tissues were quantitatively analyzed with programmed thermal analysis coupled with a sequential digestion. Programmed thermal analysis evidenced a linear relationship between c-MWCNT-bound C and elemental C detected. A detection limit of 114-708 μg C g-1 plant tissues (dry mass) was achieved for analysis of c-MWCNTs. The method was demonstrated using the tissues of lettuce cultured hydroponically for 3 wk with c-MWCNTs at an exposure of 10 and 20 μg ml-1 . This quantitative analysis can be used to provide insights into carbon nanotube exposure through agricultural products and promote its sustainable application.

Mitigation of environmentally-related hazardous pollutants from water matrices using nanostructured materials - A review

An unprecedented rise in population growth and rapid worldwide industrial development are associated with the increasing discharge of a range of toxic and baleful compounds. These toxic pollutants including dyes, endocrine-disrupters, heavy metals, personal care products, and pharmaceuticals are destructing nature's balance and intensifying environmental toxicity at a disquieting rate. Therefore, finding better, novel and more environmentally sound approaches for wastewater remediation are of great importance. Nanoscale materials have opened up some new horizons in various fields of science and technology. Among a range of treatment technologies, nanostructured materials have recently received incredible interest as an emerging platform for wastewater remediation owing to their exceptional surface-area-to-volume ratio, unique electrical and chemical properties, quantum size effects, high scalability, and tunable surface functionalities. An array of nanomaterials including noble metal-based nanostructures, transition metal oxide nanomaterials, carbon-based nanomaterials, carbon nanotubes, and graphene/graphene oxide nanomaterials to their novel nanocomposites and nanoconjugates have been attempted as the promising catalysts to overcome environmental dilemmas. In this review, we summarized recent advances in nanostructured materials that are particularly engineered for the remediation of environmental contaminants. The toxicity of various classes of relevant tailored nanomaterials towards human health and the ecosystem along with perspectives is also presented. In our opinion, an overview of the up-to-date advancements on this emerging topic may provide new ideas and thoughts for engineering low-cost and highly-efficient nanostructured materials for the abatement of recalcitrant pollutants for a sustainable environment.

Lysosomes, Autophagy, and Hormesis in Cell Physiology, Pathology, and Age-Related Disease

Autophagy has been strongly linked with hormesis, however, it is only relatively recently that the mechanistic basis underlying this association has begun to emerge. Lysosomal autophagy is a group of processes that degrade proteins, protein aggregates, membranes, organelles, segregated regions of cytoplasm, and even parts of the nucleus in eukaryotic cells. These degradative processes are evolutionarily very ancient and provide a survival capability for cells that are stressed or injured. Autophagy and autophagic dysfunction have been linked with many aspects of cell physiology and pathology in disease processes; and there is now intense interest in identifying various therapeutic strategies involving its regulation. The main regulatory pathway for augmented autophagy is the mechanistic target of rapamycin (mTOR) cell signaling, although other pathways can be involved, such as 5'-adenosine monophosphate-activated protein kinase. Mechanistic target of rapamycin is a key player in the many highly interconnected intracellular signaling pathways and is responsible for the control of cell growth among other processes. Inhibition of mTOR (specifically dephosphorylation of mTOR complex 1) triggers augmented autophagy and the search is on the find inhibitors that can induce hormetic responses that may be suitable for treating many diseases, including many cancers, type 2 diabetes, and age-related neurodegenerative conditions.

Is nano ZnO/chlorpyrifos mixture more harmful to earthworms than bulk ZnO? A multigeneration approach

As chlorpyrifos is one of the most widely used organophosphorus insecticides and ZnO-NPs are identified as NPs of the highest concern due to their negative effects on aquatic and soil organisms the objective of this study was to evaluate mixture toxicity of CHP and ZnO (bulk and nanoparticles (20 nm)) on two types of soil, artificial (AS) and natural (NS), and over two generations of earthworms. Primary endpoint measured was reproduction inhibition and biochemical biomarkers (acetylcholinesterase, catalase, glutathione-S transferase and malondialdehyde content). Results showed that mixture toxicity differs in respects to all tested factors: soil type, ZnO particle size and earthworm generation. CHP/ZnO mixtures had synergistic effects and significantly reduced a number of juveniles in both generations in AS, while the effects were additive or even antagonistic in NS. There was no difference in reproduction inhibition in respect to particle size of ZnO used in the mixtures. Negative effects could also be detected on growth dynamics of juvenile earthworms (2nd generation) as they had lower initial body mas, reduced growth rate and lower body mass as adults. Measured enzymes responded differently in respect to ZnO particle size used in the mixtures, with CHP/bZnO producing stronger effects. Measured concentrations of the bioavailable Zn in the soils showed no difference in the concentration of bioavailable Zn²⁺ between mixtures, but significantly more Zn²⁺ was retrieved from AS. General biomarker response indicated that 2nd generation of earthworms had lower capability to cope with oxidative stress.

Postnatal distribution of ZnO nanoparticles to the breast milk through oral route and their risk assessment for breastfed rat offsprings

Various studies in rodents have shown that nanoparticles are transferred to the breast milk. Under the present study, lactating Wistar rats were repetitively gavaged 5, 25, and 50 mg/kg bw of zinc oxide nanoparticles (ZnO-NPs) and 50 mg kg^-1 bw of bulk zinc oxide (bZnO) for 19 days after parturition. The results showed that ZnO-NPs were absorbed in the small intestine of dams and distributed to the liver. Furthermore, ZnO-NPs were distributed to the intestine and liver of rat pups through dam's milk. No significant change in body weight was observed in the dams treated with ZnO-NPs or bZnO and their offsprings as compared to the control group. The spleen weight significantly increased in the rat dams treated with 50 mg kg^-1 of ZnO-NPs. ZnO-NPs were mostly excreted through feces. The levels of liver cytochrome P450 reductase and serum total antioxidant capacity significantly decreased in the rat dams treated with ZnO-NPs (50 mg kg^-1) and their offsprings. The levels of serum cytokines (tumor necrosis factor-alpha and interleukin-1 beta) and liver injury marker enzymes (alanine aminotransferase and aspartate aminotransferase) significantly increased in the rat dams treated with ZnO-NPs (25 and 50 mg kg^-1) and their offsprings. The level of immunoglobulin A secretion in the intestinal fluid of rat dams and their offsprings is significantly increased by increasing the dose of ZnO-NPs. Histopathology of intestine and liver of offsprings whose rat dams were treated with ZnO-NPs (50 mg kg^-1) showed gross pathological changes. These results provide information for the safety evaluation of ZnO-NPs use during lactation. In conclusion, a dose-dependent postnatal transfer of ZnO-NPs is hazardous to the breastfed offsprings.

Oral Co-Exposures to zinc oxide nanoparticles and CdCl2 induced maternal-fetal pollutant transfer and embryotoxicity by damaging placental barriers

Synergistic toxicity from multiple environmental pollutants poses greater threat to humans, especially to susceptible pregnant population. Here we evaluated combined toxicity from environment pollutants zinc oxide nanoparticles (ZnO NPs) and cadmium chloride (CdCl₂) using two pregnant mice models established by oral administration during peri-implantation or organogenesis period. We found that exposures to combined pollutants only at organogenesis stage induced higher fetal deformity rate compared to co-exposures at peri-implantation stage. We further discovered that surface charge of ZnO NPs were modified after Cd²⁺ adsorption and the resulting nanoadducts caused more severe damages in placental barriers by causing shed endothelial cells and decreased expressions of tight junction proteins ZO1, occludin, claudin-4 and claudin-8. These cellular and molecular events enhanced maternal-fetal transfer of both pollutants and aggravated embryotoxicity. Our findings help elucidate synergistic embryotoxicity by nanoparticle/pollutant adducts and establish proper safety criteria for pregnant population in an era that nanotechnology-based products are widely used.

Common Gene Expression Patterns in Environmental Model Organisms Exposed to Engineered Nanomaterials: A Meta-Analysis

The use of omics is gaining importance in the field of nanoecotoxicology; an increasing number of studies are aiming to investigate the effects and modes of action of engineered nanomaterials (ENMs) in this way. However, a systematic synthesis of the outcome of such studies regarding common responses and toxicity pathways is currently lacking. We developed an R-scripted computational pipeline to perform reanalysis and functional analysis of relevant transcriptomic data sets using a common approach, independent from the ENM type, and across different organisms, including Arabidopsis thaliana, Caenorhabditis elegans, and Danio rerio. Using the pipeline that can semiautomatically process data from different microarray technologies, we were able to determine the most common molecular mechanisms of nanotoxicity across extremely variable data sets. As expected, we found known mechanisms, such as interference with energy generation, oxidative stress, disruption of DNA synthesis, and activation of DNA-repair but also discovered that some less-described molecular responses to ENMs, such as DNA/RNA methylation, protein folding, and interference with neurological functions, are present across the different studies. Results were visualized in radar charts to assess toxicological response patterns allowing the comparison of different organisms and ENM types. This can be helpful to retrieve ENM-related hazard information and thus fill knowledge gaps in a comprehensive way in regard to the molecular underpinnings and mechanistic understanding of nanotoxicity.

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.

Nanomaterials and nanocomposite applications in veterinary medicine

Nowadays, nanotechnology has made huge, significant advancements in biotechnology and biomedicine related to human and animal science, including increasing health safety, production, and the elevation of national income. There are various fields of nanomaterial applications in veterinary medicine such as efficient diagnostic and therapeutic tools, drug delivery, animal nutrition, breeding and reproduction, and valuable additives. Additional benefits include the detection of pathogens, protein, biological molecules, antimicrobial agents, feeding additives, nutrient delivery, and reproductive aids. There are many nanomaterials and nanocomposites that can be used in nanomedicine such as metal nanoparticles, liposomes, carbon nanotubes, and quantum dots. In the near future, nanotechnology research will have the ability to produce novel tools for improving animal health and production. Therefore, this chapter was undertaken to spotlight novel methods created by nanotechnology for application in the improvement of animal health and production. In addition, the toxicity of nanomaterials is fully discussed to avoid the suspected health hazards of toxicity for animal health safety.

Food packaging and nanotechnology: safeguarding consumer health and safety

Purpose

Nanotechnology as an emerging area if adequately harnessed could revolutionise food packaging and food processing industry worldwide. Although several benefits of nano-materials or particles in food packaging have been suggested, potential risks and health hazards of nano-materials or particles are possible as a result of migration of their particles into food materials. The purpose of this review therefore assessed nanotechnology and its applications in food packaging, consumer acceptability of nano-packaged foods and potential hazards and safety issues in nano-packaged foods.

Design/methodology/approach

This review takes a critical assessment of previous literature on nanotechnology and its impact on food packaging, consumer health and safety.

Findings

Applications of nanotechnology in food packaging could be divided into three main divisions: improved packaging, which involves mixing nano-materials into polymers matrix to improve temperature, humidity and gas barrier resistance of the packaging materials. Active packaging deals with direct interaction between nano-materials used for packaging and the food to protect it as anti-microbial or oxygen or ultra violet scavengers. Smart packaging could be used to sense biochemical or microbial changes in foods, as well as a tracker for food safety, to prevent food counterfeit and adulteration. The review also discussed bio-based food packaging which is biodegradable. Bio-based packaging could serve as veritable alternative to conventional packaging which is non-degradable plastic polymers which are not environmental friendly and could pose a threat to the environment. However, bio-based packaging could reduce material waste, elongate shelf life and enhance food quality. However, several challenges are envisaged in the use of nano-materials in food packaging due to knowledge gaps, possible interaction with food products and possible health risks that could result from the nano-materials used for food packaging.

Originality/value

The increase in growth and utilisation of nanotechnology signifies wide use of nano-materials especially in the food sector with arrays of potential benefits in the areas of food safety and quality, micronutrients and bioactive ingredients delivery, food processing and in packaging Active studies are being carried out to develop innovative packages such as smart, intelligent and active food packaging to enhance effective and efficient packaging, as well as balanced environmental issues. This review looks at the future of nano-packaged foodsvis-à-visthe roles played by stakeholders such as governments, regulatory agencies and manufacturers in looking into consumer health and safety issues related to the application of nano-materials in food packaging.

Protective effect of dietary vitamin E on immunological and biochemical induction through silver nanoparticles (AgNPs) inclusion in diet and silver salt (AgNO3) exposure on Zebrafish (Danio rerio)

The present study evaluated silver nanoparticle (AgNPs) toxicity using biomarkers of oxidative and metabolic stress, immunological impairment and cellular damage in zebrafish (Danio rerio), as well as the optimal dose of vitamin E neutralizing undesirable effects. Fish were fed for ten days and eight study groups were investigated: controls, AgNPs exposure alone (1.5 mg L^-1) and combined with three different vitamin E doses (1.5 mg L^-1 of AgNPs + vitamin E 100, 200 or 400 mg kg^-1 of food), also one positive control group exposed to AgNO₃ alone or combined with the same vitamin E doses. D. rerio exposed to AgNPs alone or combined with the lower vitamin E dose showed overall worse results in comparison with the control groups and the groups combining nanoparticles and 200 or 400 mg kg^-1 of food of vitamin E-supplemented diet. AgNPs caused cell impairment by increasing LDH activity and cortisol levels, generated oxidative stress by inhibiting SOD and CAT activity and immunosuppression by inhibiting ACH50 and lysozyme activity. The groups exposed to Ag salt showed the same response-pattern found for the NPs groups, reinforcing that Ag toxicity of AgNPs is mediated by Ag⁺. In conclusion, although AgNPs are toxic to Danio rerio, vitamin E supplementation at 200 or 400 mg kg^-1 can act protectively against its toxic effects.

Cytotoxicity of CdTe quantum dots with different surface coatings against yeast Saccharomyces cerevisiae

Cadmium (Cd)-based QDs are well studied owing to their excellent optical properties. The applications of Cd-based QDs in biomedical filed, however, is hindered by its inherent toxicity. In this study, to overcome the inherent toxicity of heavy metals, CdTe QDs were encapsulated with different shells (NAC, MPA and GSH) to reduce the leakage of Cd from the core. We studied the cytotoxicity of the three kinds of CdTe QDs on S. cerevisiae by spectroscopic, electrochemical, microscopic methods and microcalorimetric technique. Results showed that toxicity of CdTe QDs increased with the augment of QD concentration. According to the values of IC₅₀ ((GSH-CdTe QDs (15.3 nmol/L) < MPA-CdTe QDs (56.2 nmol/L) < NAC-CdTe QDs (89.8 nmol/L)), the most toxic one is GSH-CdTe QDs, followed by MPA-CdTe QDs, then NAC-CdTe QDs. The coatings have contribution to their toxicity. The three kinds of QDs with the similar shape (sphere) can enter the cell by the clathrin-mediated endocytosis and lead to the different impairments. The mechanism of cytotoxicity is due to the release of Cd²⁺ leading elevation of intracellular reactive oxygen species (ROS), which damage mitochondria. The clathrin-mediated endocytosis is a significant factor in determining the toxicity of CdTe QDs.

Comparative dissolution, uptake, and toxicity of zinc oxide particles in individual aquatic species and mixed populations

Potential differences in species susceptibility to nanoparticle (NP) contaminants make the use of multispecies community toxicity testing strategies beneficial in understanding NP risk to aquatic environments. Because of the limited knowledge of zinc oxide (ZnO) NP fate and toxicity, we conducted multispecies exposures and compared the responses of individual species to the same species in a community comprised of algae (Chlamydomonas reinhardtii), bacteria (Escherichia coli), crustaceans (Daphnia magna), and zebrafish (Danio rerio). Different-sized ZnO particles and ionic Zn were compared to investigate the contribution of particulate and dissolved Zn to aquatic organism toxicity. Each organism and community was exposed to Zn sources at 0.08, 0.8, and 8 mg Zn/L. The present results indicate that all 3 types of Zn elicited differential toxicity among test organisms, with stronger adverse outcomes observed in single species than within a community. The community assay (nanocosm) we developed increased resilience to all Zn exposures by 5 to 10% compared to individual exposures at equivalent concentrations. In addition, the uptake and toxicity of ZnO particles to aquatic communities appear to be driven by rapid dissolution and the concomitant impacts of zinc ion toxicity, and the size of the ZnO particles had little impact on uptake or toxicity. The nanocosm assay could be a useful screening tool for rapidly assessing the potential impacts of nanomaterials to aquatic species. Environ Toxicol Chem 2019;38:591-602. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Prioritization of pesticides in crops with a semi-quantitative risk ranking method for Taiwan postmarket monitoring program

A risk-based prioritization of chemical hazards in monitoring programs allows regulatory agencies to focus on the most potentially concerned items involving human health risk. In this study, a risk-based matrix, with a scoring method using multiple factors for severity and probability of exposure, was employed to identify the pesticides presented in crops that may pose the greatest risk to human health. Both the probability of exposure and the severity were assessed for 91 pesticides detected in a Taiwanese postmarketing monitoring program. Probability of exposure was evaluated based on the probability of consumption and evidence of pesticide residues in crops. Severity was assessed based on the nature of the hazard (i.e., the description of toxic effects), and the acceptable daily intake (ADI) reported by available toxicological reports. This study showed that the nature of the hazard and probability of consumption had the strongest contribution to risk score. Dithiocarbamates, endosulfan, and carbofuran were identified as the pesticides with the highest concern for human health risks in Taiwan. These pesticides should be monitored more frequently than others in crops during the postmarketing monitoring program. However, some uncertainties shall be noted or improved when this methodology is applied for risk prioritization in the future.

The effects of silver nanomaterial shape and size on toxicity to Caenorhabditis elegans in soil media

Silver nanomaterials (AgNMs) of various shapes and sizes are manufactured for different purposes and used as ingredients in a wide variety of products and applications. Recently, the toxicity of AgNMs has attracted significant attention. However, the effect of the shape of AgNMs (particles, wires, plates) on their toxicity in soil ecosystems remains poorly understood. In this study, we added AgNMs of different shapes and sizes (silver nanoparticles, AgNPs; 10 μm silver nanowires, 10-AgNWs; 20 μm silver nanowires, 20-AgNWs; silver nanoplates, AgPLs) to natural soil and determined their effect on the growth and reproduction of the free-living nematode, Caenorhabditis elegans. AgNPs and AgPLs were found to inhibit the growth and reproduction of C. elegans, whereas AgNWs had a negligible effect. Among these AgNMs, the results of this study suggest AgNPs are the most toxic. This confirms that the shape of AgNPs plays a significant role in their toxicity level. To the best of our knowledge, this is the first comparative analysis of the shape-dependent toxicity of AgNMs in the soil using nematode C. elegans. This study provides a scientific reference for assessing shape-dependent soil nanotoxicity.

Toxic effect of triphenyltin in the presence of nano zinc oxide to marine copepod Tigriopus japonicus

Marine organisms are naturally exposed to different environmental pollutants including organic pollutants and nanoparticles. The interactive effects between nanoparticles and other chemicals on aquatic organisms have raised concerns regarding the potential of nanomaterials as the vector for other chemicals. In the present study, the effect of nano zinc oxide (nZnO) on the bioavailability of triphenyltin chloride (TPTCl) was studied, and their combined acute and reproductive toxicity to the marine copepod Tigriopus japonicus were evaluated. At experimental concentration ranges of nZnO in this study, the percentage of dissolution of Zn²⁺ was relative stable (from 62% to 66%), and nZnO did not affect the bioavailability of TPTCl to the copepods. The acute toxicity of binary mixtures of nZnO/TPT was equivalent to that of the mixture of Zn²⁺/TPT. In agreement with the decrease in TPTCl's LC₅₀ values at the presence of nZnO, their interacting effect was synergistic based on response addition response surface model, and the interacting parameter was modelled to be -1.43. In addition to acute toxicity test, reproductive toxicity tests revealed that exposure to nZnO and TPTCl didn't affect the successful mating rate and the number of nauplii in the 1st brood, but they extended the time for the eggs to hatch from 2.53 days to 3.94 and 3.64 days, respectively. The exposure to nZnO/TPTCl mixture delayed the time to hatch to 5.78 days.

Effect of Nano-SiO2 on Expression and Aberrant Methylation of Imprinted Genes in Lung and Testis

Nanotechnology has been developing rapidly and is now used in many cutting-edge medical therapeutics. However, there is increasing concern that exposure to nanoparticles (NPs) may induce different systemic diseases as epigenetic mechanisms are associated with more and more disease. The role of NP epigenomic modification is important to disease etiology. Our study aimed to determine the epigenetic mechanisms of damage in lung and testis cells by exposing cells to SiO₂ NPs. We used male C57BL/6 mice to characterize the damaging effect of SiO₂ NPs on lung and testis cells as well as the resulting methylation state at the imprinted Dlk1/Dio3 domain region. The A549 cells exposed to SiO₂ NPs had cell apoptosis, and male mice exposed to SiO₂ NPs had altered lung and testis tissues. The genes in the imprinted domains Dlk1/Dio3 region changed in both tissues; Dlk1, Rtl1, and Dio3 are upregulated in testis while Dlk1 and Dio3 are also upregulated in lung tissues. Bisulfite sequencing PCR of male adult lung and testis were mostly hypomethylated, with a few hypermethylated CpGs. These findings indicate that nanoparticles play an important role in DNA methylation of imprinted genes.

An overview of graphene materials: Properties, applications and toxicity on aquatic environments

Due to unique chemical and physical properties, nanomaterials from the Graphene family are being increasingly introduced in all fields of science. The specific roles they can occupy within different applications are attracting increased attention by several industrial sectors. These carbon nanoparticles are released into the environment especially accumulating in aquatic systems. Since the discovery of graphene, a number of research actives are being conducted to find out the toxic potential of the Graphene family materials to different organism's models. Although their toxicity effects are well described for biomedical applications, few data were produced with the specific aim of assessing the toxic effects of these carbon nanomaterials in the aquatic environment. The purpose of this review is to compile up-to-date information on properties, applications and characterization methods of graphene family materials in aquatic environments and identified biological toxic impacts of these NMs, with special focus on graphene oxide based on the most recent literature.

Comparative effects of graphene and graphene oxide on copper toxicity to Daphnia magna: Role of surface oxygenic functional groups

Although the risk of graphene materials to aquatic organisms has drawn wide attention, the combined effects of graphene materials with other contaminants such as toxic metals, which may bring about more serious effects than graphene materials alone, have seldom been explored. Herein, the effects of graphene (GN) and graphene oxide (GO, an important oxidized derivative of graphene) on copper (Cu) toxicity to Daphnia magna were systematically investigated. The results indicated that GN remarkably increased the Cu accumulation in D. magna and enhanced the oxidative stress injury caused by Cu, whereas did not significantly alter D. magna acute mortality within the tested Cu concentrations (0-200 μg L^-1). On the contrary, GO significantly decreased the Cu accumulation in D. magna and alleviated the oxidative stress injury caused by Cu. Meanwhile, the presence of GO significantly reduced the mortality of D. magna when Cu concentration exceeded 50 μg L^-1. The different effects of GN and GO on Cu toxicity were possibly dependent on the action of surface oxygenic functional group. Because of the introduction of surface oxygenic functional groups, the adsorption ability to metal ions, stability in water and interaction mode with organisms of GO are quite different from that of GN, causing different effects on Cu toxicity. This study provides important information on the bioavailability and toxicity of heavy metals as affected by graphene materials in natural water.

Nano titanium exposure induces dose- and size-dependent cytotoxicity on human epithelial lung and colon cells

The productions as well as use of Titanium dioxide nanoparticles (TNPs) were rapidly increasing in the present nano-world. The TNP becomes an inevitable part our daily life in the form of cosmeceutical, bio-medical, and nano-pharmaceutical applications. The TNPs are either inhaled or ingested into the human body through common routes of exposure like the lungs and the oral-gastrointestinal tract (GIT). Human lung and colon were exposed to test particles, TNP 18 nm (TNP 18), TNP 30 nm (TNP 30), and TNP 87 nm (TNP 87) with a dose range 0.1-100 µg/ml. The effect of exposure was determined using MTT, LDH, and DCFH-DA methods. The TNP 18, TNP 30, and TNP 87 significantly (p < 0.001) reduced cell viability in a dose- and a size-dependent manner in 60 and 100 µg/ml. The lowest IC₅₀ values 21.80 and 24.83 µg/ml were observed in A549 and Caco-2 for the smallest size, TNP 18. Further, for TNP 30, IC₅₀ values were 23.30 and 28.59 µg/ml compared to Nano QTZ 43.82 and 45.86 µg/ml. The EC₂₅ values of LDH leakage were 5.83 and 9.50 µg/ml for TNP 18 in lung and colon cells. Besides, ROS levels increased significantly at doses 60 (p < 0.01) and 100 (p < 0.001) µg/ml in two cells. The smaller size particle, TNP 18 has produced a significant (p < 0.05) toxic effect at the lowest dose i.e., 10 µg/ml. Therefore, we conclude that TNP 18, TNP 30, and TNP 87 induced a dose- and size-dependent cytotoxicity via decreased cell viability, increased LDH and ROS levels by in vitro methods.

Quantification of Au Nanoparticle Biouptake and Distribution to Freshwater Algae Using Single Cell - ICP-MS

Quantifying metal and nanoparticle (NP) biouptake and distribution on an individual cellular basis has previously been impossible, given available techniques which provide qualitative data that are laborious to acquire and prone to artifacts. Quantifying metal and metal NP uptake and loss processes in environmental organisms will lead to mechanistic understanding of biouptake and improved understanding of potential hazards and risks of metals and NPs. In this work, we present a new technique, single cell inductively coupled plasma mass spectrometry (SC-ICP-MS), which allows quantification of metal concentrations on an individual cell basis down to the attogram (ag) per cell level. We present data validating the novel method, along with the mass of metal per cell. Finally, we use SC-ICP-MS, with ancillary cell counting methods, to quantify the biouptake and strong sorption and distribution of both dissolved Au and Au NPs in a freshwater alga (Cyptomonas ovate). The data suggests differences between dissolved and NP uptake and loss. In the case of NPs, there was a dose and time dependent uptake, but individual cellular variations; at the highest realistic exposure conditions used in this study up to 40-50% of cells contained NPs, while 50-60% of cells did not.

Application of nanoparticle tracking analysis for characterising the fate of engineered nanoparticles in sediment-water systems

Novel applications of nanotechnology may lead to the release of engineered nanoparticles (ENPs), which result in concerns over their potential environmental hazardous impact. It is essential for the research workers to be able to quantitatively characterise ENPs in the environment and subsequently to assist the risk assessment of the ENPs. This study hence explored the application of nanoparticle tracking system (NTA) to quantitatively describe the behaviour of the ENPs in natural sediment-water systems. The NTA allows the measurement of both particle number concentration (PNC) and particle size distribution (PSD) of the ENPs. The developed NTA method was applied to a range of gold and magnetite ENPs with a selection of surface properties. The results showed that the positively-charged ENPs interacted more strongly with the sediment than neutral and negatively-charged ENPs. It was also found that the citrate coated Au ENPs had a higher distribution percentage (53%) than 11-mercaptoundecanoic acid coated Au ENPs (20%) and citrate coated magnetite ENPs (21%). The principles of the electrostatic interactions between hard (and soft) acids and bases (HSAB) are used to explain such behaviours; the hard base coating (i.e. citrate ions) will interact more strongly with hard acid (i.e. magnetite) than soft acid (i.e. gold). The results indicate that NTA is a complementary method to existing approaches to characterise the fate and behaviour of ENPs in natural sediment.

Environmental Risk Assessment Strategy for Nanomaterials

An Environmental Risk Assessment (ERA) for nanomaterials (NMs) is outlined in this paper. Contrary to other recent papers on the subject, the main data requirements, models and advancement within each of the four risk assessment domains are described, i.e., in the: (i) materials, (ii) release, fate and exposure, (iii) hazard and (iv) risk characterisation domains. The material, which is obviously the foundation for any risk assessment, should be described according to the legislatively required characterisation data. Characterisation data will also be used at various levels within the ERA, e.g., exposure modelling. The release, fate and exposure data and models cover the input for environmental distribution models in order to identify the potential (PES) and relevant exposure scenarios (RES) and, subsequently, the possible release routes, both with regard to which compartment(s) NMs are distributed in line with the factors determining the fate within environmental compartment. The initial outcome in the risk characterisation will be a generic Predicted Environmental Concentration (PEC), but a refined PEC can be obtained by applying specific exposure models for relevant media. The hazard information covers a variety of representative, relevant and reliable organisms and/or functions, relevant for the RES and enabling a hazard characterisation. The initial outcome will be hazard characterisation in test systems allowing estimating a Predicted No-Effect concentration (PNEC), either based on uncertainty factors or on a NM adapted version of the Species Sensitivity Distributions approach. The risk characterisation will either be based on a deterministic risk ratio approach (i.e., PEC/PNEC) or an overlay of probability distributions, i.e., exposure and hazard distributions, using the nano relevant models.

Nanotechnology: An Untapped Resource for Food Packaging

Food commodities are packaged and hygienically transported to protect and preserve them from any un-acceptable alteration in quality, before reaching the end-consumer. Food packaging continues to evolve along-with the innovations in material science and technology, as well as in light of consumer's demand. Presently, the modern consumers of competitive economies demands for food with natural quality, assured safety, minimal processing, extended shelf-life and ready-to-eat concept. Innovative packaging systems, not only ascertains transit preservation and effective distribution, but also facilitates communication at the consumer levels. The technological advances in the domain of food packaging in twenty-first century are mainly chaired by nanotechnology, the science of nano-materials. Nanotechnology manipulates and creates nanometer scale materials, of commercial and scientific relevance. Introduction of nanotechnology in food packaging sector has significantly addressed the food quality, safety and stability concerns. Besides, nanotechnology based packaging intimate's consumers about the real time quality of food product. Additionally, nanotechnology has been explored for controlled release of preservatives/antimicrobials, extending the product shelf life within the package. The promising reports for nanotechnology interventions in food packaging have established this as an independent priority research area. Nanoparticles based food packages offer improved barrier and mechanical properties, along with food preservation and have gained welcoming response from market and end users. In contrary, recent advances and up-liftment in this area have raised various ethical, environmental and safety concerns. Policies and regulation regarding nanoparticles incorporation in food packaging are being reviewed. This review presents the existing knowledge, recent advances, concerns and future applications of nanotechnology in food packaging sector.

Synergistic mitotoxicity of chloromethanes and fullerene C60 nanoaggregates in Daphnia magna midgut epithelial cells

Adsorption of non-polar compounds by suspended fullerene nanoaggregates (nC₆₀) may enhance their toxicity and affect the fate, transformation, and transport of non-polar compounds in the environment. The potential of stable fullerene nanoaggregates as contaminant carriers in aqueous systems and the influence of chloromethanes (trichloromethane and dichloromethane) were studied on the midgut epithelial cells of Daphnia magna by light and electron microscopy. The size and shape of fullerene nanoaggregates were observed and measured using dynamic light scattering, transmission electron microscopy, and low vacuum scanning electron microscopy. The nC₆₀ in suspension appeared as a bulk of aggregates of irregular shape with a surface consisting of small clumps 20-30 nm in diameter. The presence of nC₆₀ aggregates was confirmed in midgut lumen and epithelial cells of D. magna. After in vivo acute exposure to chloromethane, light and electron microscopy revealed an extensive cytoplasmic vacuolization with disruption and loss of specific structures of D. magna midgut epithelium (mitochondria, endoplasmic reticulum, microvilli, peritrophic membrane) and increased appearance of necrotic cells. The degree of observed changes depended on the type of treatment: trichloromethane (TCM) induced the most notable changes, whereas fullerene nanoaggregates alone had no negative effects. Transmission electron microscopy also indicated increased lysosomal degradation and severe peroxidative damages of enterocyte mitochondria following combined exposure to chloromethane and fullerene nanoaggregates. In conclusion, the adsorption of chloromethane by fullerene nanoaggregates enhances their toxicity and induces peroxidative mitochondrial damage in midgut enterocytes.

Where do uncertainties reside within environmental risk assessments? Testing UnISERA, a guide for uncertainty assessment

A means for identifying and prioritising the treatment of uncertainty (UnISERA) in environmental risk assessments (ERAs) is tested, using three risk domains where ERA is an established requirement and one in which ERA practice is emerging. UnISERA's development draws on 19 expert elicitations across genetically modified higher plants, particulate matter, and agricultural pesticide release and is stress tested here for engineered nanomaterials (ENM). We are concerned with the severity of uncertainty; its nature; and its location across four accepted stages of ERAs. Using an established uncertainty scale, the risk characterisation stage of ERA harbours the highest severity level of uncertainty, associated with estimating, aggregating and evaluating expressions of risk. Combined epistemic and aleatory uncertainty is the dominant nature of uncertainty. The dominant location of uncertainty is associated with data in problem formulation, exposure assessment and effects assessment. Testing UnISERA produced agreements of 55%, 90%, and 80% for the severity level, nature and location dimensions of uncertainty between the combined case studies and the ENM stress test. UnISERA enables environmental risk analysts to prioritise risk assessment phases, groups of tasks, or individual ERA tasks and it can direct them towards established methods for uncertainty treatment.

Needs and challenges for assessing the environmental impacts of engineered nanomaterials (ENMs)

The potential environmental impact of nanomaterials is a critical concern and the ability to assess these potential impacts is top priority for the progress of sustainable nanotechnology. Risk assessment tools are needed to enable decision makers to rapidly assess the potential risks that may be imposed by engineered nanomaterials (ENMs), particularly when confronted by the reality of limited hazard or exposure data. In this review, we examine a range of available risk assessment frameworks considering the contexts in which different stakeholders may need to assess the potential environmental impacts of ENMs. Assessment frameworks and tools that are suitable for the different decision analysis scenarios are then identified. In addition, we identify the gaps that currently exist between the needs of decision makers, for a range of decision scenarios, and the abilities of present frameworks and tools to meet those needs.

Health risks associated with the pharmaceuticals in wastewater

The overwhelming population growth in recent decades and water crisis along with limited and uneven geographical distribution of fresh water resources is a growing challenge for the economic and human development. Wastewater reclamation and use could be an alternative for intact water sources and a promising solution to water scarcity and unequal distribution. However, wastewater is a double-edged resource both as an accessible water source for food production and human usage and concurrently may carry uncharacterized content with unknown toxicological profile causing acute or long-term health risks. Pharmaceuticals, cosmeceuticals, nanomaterials and their chemical decomposition derivatives found in wastewater are not well known in many cases. Their unknown toxicity, teratogenicity and carcinogenicity profile associated with lack of monitoring and control measures impose a significant hazard risk on the public health. This paper reviews the evidence on the health risks associated with the wastewater use for irrigated food production and the imposed risk on the end consumers mainly from pharmaceutical industry and related research facilities. Then, we suggest an applied framework for planning and policy-making to mitigate the health risks and optimally employ reclaimed wastewater for human purposes.