Agrochemical inputs to managed oil palm plantations are a probable risk to ecosystems: Results from a screening level risk assessment

Palm oil is a high value crop widely grown in the tropics. The management of palm oil is characterised by widespread agrochemical use. Here we report the results of a screening level risk assessment conducted from the available literature on the environmental concentration of agrochemicals in surface waters and soils in palm oil growing areas. To date, only a small number of published studies have measured pollutant concentrations in and around palm oil plantations. To identify potential high-risk contaminants, a standard SSD based risk assessment, establishing risk quotients for detected contaminants, was conducted in relation to available species sensitivity distributions. A probabilistic SSD based risk assessment, calculating potential risk distributions, was also conducted for contaminants with the required number of data points available. Metals were the most commonly detected (and measured) substances and also presented the greatest risk, especially copper and zinc, but also nickel, lead and cadmium. For these metals, environmental concentrations overlapped levels found to cause effects in toxicity studies, indicating the potential for adverse outcomes from exposure. To fully understand the extent of this risk, more detailed studies are needed that assess metal speciation states and bioavailability under the prevailing soil and water chemistry conditions in palm oil plots. Limited studies have measured pesticide concentrations in palm oil systems. In these few cases, only a few active substances have been measured. From the limited information available, potential risks are indicated due to the presence of some insecticides. However, fungicides are also widely used for palm oil disease management, but little data studies are available to assess both exposure and potential effects. To further assess the potential chemical footprint of different palm oil management practices, studies are needed that systematically assess pollutant levels across a range of chemical groups to consider effects within a mixture context.

Improved control of Trialeurodes vaporariorum using mixture combinations of entomopathogenic fungi and the chemical insecticide spiromesifen

Greenhouse whitefly (Trialeurodes vaporariorum) is a major global pest, causing direct damage to plants and transmitting viral plant diseases. Management of T. vaporariorum is problematic because of widespread pesticide resistance, and many greenhouse growers rely on biological control agents to regulate T. vaporariorum populations. However, these are often slow and vary in efficacy, leading to subsequent application of chemical insecticides when pest populations exceed threshold levels. Combining chemical and biological pesticides has great potential but can result in different outcomes, from positive to negative interactions. In this study, we evaluated co-applications of the entomopathogenic fungi (EPF) Beauveria bassiana and Cordyceps farinosa and the chemical insecticide spiromesifen in laboratory bioassays. Complex interactions between the EPFs and insecticide were described using an ecotoxicological mixtures model, the MixTox analysis. Depending on the EPF and chemical concentrations applied, mixtures resulted in additivity, synergism, or antagonism in terms of total whitefly mortality. Combinations of B. bassiana and spiromesifen, compared to single treatments, increased the rate of kill by 5 days. Results indicate the potential for combined applications of EPF and spiromesifen as an effective integrated pest management strategy and demonstrate the applicability of the MixTox model to describe complex mixture interactions.

Assessing the relevance of environmental exposure data sets

Environmental exposure data are used by decision-makers to assess environmental risks and implement actions to mitigate risks from contaminants. The first article in this series summarized the available evaluation schemes for environmental exposure data, of which there are few compared to those available for environmental hazard data. The second article covered the assessment of the reliability of environmental exposure data sets under the Criteria for the Reporting and Evaluation of Exposure Data (CREED). The aim of this article is to provide an overview and practical guidance on the relevance assessment in the context of the CREED approach for evaluating exposure monitoring data sets. Systematically considering relevance is critical for both evaluating existing data sets and for optimizing the design of new monitoring studies. Relevance is defined here as the degree of suitability or appropriateness of a data set to address a specific purpose or to answer the questions that have been defined by the assessor or for those generating exposure data. The purpose definition will be the foundation for the relevance assessment, to clarify how the assessor should rate the assessment criteria (fully met, partly met, not met/inappropriate, not reported, not applicable). This will provide transparency for anyone reviewing the outcomes. An explicit gap analysis (i.e., an articulation of the data set limitations for the stated purpose) is an important outcome of the relevance assessment. The relevance evaluation approach is demonstrated with three case studies, all relating to the freshwater aquatic environment, where the data sets are scored as relevant with or without restrictions, not relevant, or not assignable. The case studies represent both organic and inorganic constituents, and have different data characteristics (e.g., percentage of censored data, sampling frequencies, relation to supporting parameters). Integr Environ Assess Manag 2024;20:1004-1018. © 2023 SETAC.

Toxicokinetics and bioaccumulation of silver sulfide nanoparticles in benthic invertebrates in an indoor stream mesocosm

Mesocosms allow the simulation of environmentally relevant conditions and can be used to establish more realistic scenarios of organism exposure to nanoparticles. An indoor mesocosm experiment simulating an aquatic stream ecosystem was conducted to assess the toxicokinetics and bioaccumulation of silver sulfide nanoparticles (Ag₂S NPs) and AgNO₃ in the freshwater invertebrates Girardia tigrina, Physa acuta and Chironomus riparius, and determine if previous single-species tests can predict bioaccumulation in the mesocosm. Water was daily spiked at 10 μg Ag L^-1. Ag concentrations in water and sediment reached values of 13.4 μg Ag L^-1 and 0.30 μg Ag g^-1 in the Ag₂S NP exposure, and 12.8 μg Ag L^-1 and 0.20 μg Ag g^-1 in the AgNO₃. Silver was bioaccumulated by the species from both treatments, but with approximately 1.5, 3 and 11 times higher body Ag concentrations in AgNO₃ compared to Ag₂S NP exposures in snails, chironomids and planarians, respectively. In the Ag₂S NP exposures, the observed uptake was probably of the particulate form. This demonstrates that this more environmentally relevant Ag nanoform may be bioavailable for uptake by benthic organisms. Interspecies interactions likely occurred, namely predation (planarians fed on chironomids and snails), which somehow influenced Ag uptake/bioaccumulation, possibly by altering organisms´ foraging behaviour. Higher Ag uptake rate constants were determined for AgNO₃ (0.64, 80.4 and 1.12 L_water g^-1_organism day^-1) than for Ag₂S NPs (0.05, 2.65 and 0.32 L_water g^-1_organism day^-1) for planarians, snails and chironomids, respectively. Biomagnification under environmentally realistic exposure seemed to be low, although it was likely to occur in the food chain P. acuta to G. tigrina exposed to AgNO₃. Single-species tests generally could not reliably predict Ag bioaccumulation in the more complex mesocosm scenario. This study provides methodologies/data to better understand exposure, toxicokinetics and bioaccumulation of Ag in complex systems, reinforcing the need to use mesocosm studies to improve the risk assessment of environmental contaminants, specifically NPs, in aquatic environments.

Predicting accidental release of engineered nanomaterials to the environment

Challenges in distinguishing between natural and engineered nanomaterials (ENMs) and the lack of historical records on ENM accidents have hampered attempts to estimate the accidental release and associated environmental impacts of ENMs. Building on knowledge from the nuclear power industry, we provide an assessment of the likelihood of accidental release rates of ENMs within the next 10 and 30 years. We evaluate risk predictive methodology and compare the results with empirical evidence, which enables us to propose modelling approaches to estimate accidental release risk probabilities. Results from two independent modelling approaches based on either assigning 0.5% of reported accidents to ENM-releasing accidents (M1) or based on an evaluation of expert opinions (M2) correlate well and predict severe accidental release of 7% (M1) in the next 10 years and of 10% and 20% for M2 and M1, respectively, in the next 30 years. We discuss the relevance of these results in a regulatory context.

Soil properties influence the toxicity and availability of Zn from ZnO nanoparticles to earthworms

To develop models that support site-specific risk assessment for nanoparticles (NPs), a better understanding of how NP transformation processes, bioavailability and toxicity are influenced by soil properties is needed. In this study, the influence of differing soil properties on the bioavailability and toxicity of zinc oxide (ZnO) NPs and ionic Zn to the earthworm Eisenia fetida was investigated. Earthworms were exposed to ZnO_NPs and ionic Zn, between 100 and 4400 mg Zn/kg, in four different natural soils (organic matter content: 1.8-16.7%, soil pH: 5.4-8.3, representing sandy loam to calcareous soils). Survival and reproduction were assessed after 28 and 56 days, respectively. Zn concentrations in soil pore waters were measured while labile concentrations of Zn were measured using an in-situ dynamic speciation technique (diffusive gradient in thin films, DGT). Earthworm Zn tissue concentrations were also measured. Soil properties influenced earthworm reproduction between soil controls, with highest reproductive output in soils with pH values of 6-7. Toxicity was also influenced by soil properties, with EC₅₀s based on total Zn in soil ranging from 694 to >2200 mg Zn/kg for ZnO_NP and 277-734 mg Zn/kg for ionic Zn. Soil pore water and DGT measurements showed good agreement in the relative amount of Zn extracted across the four soils. Earthworms exposed to ZnO_NPs survived higher Zn concentrations in the soils and had higher tissue concentrations compared with ionic Zn exposures, particularly in the high organic content calcareous soil. These higher tissue concentrations in ZnO_NP exposed earthworm could have consequences for the persistence and trophic mobility of Zn in terrestrial systems and need to be further investigated to elucidate if there any longer-term risks associated with sustained input of ZnO_NP to soil.

Toxicokinetics of Ag from Ag2S NP exposure in Tenebrio molitor and Porcellio scaber: Comparing single-species tests to indoor mesocosm experiments

Determining the potential for accumulation of Ag from Ag₂S NPs as an environmentally relevant form of AgNPs in different terrestrial organisms is an essential component of a realistic risk assessment of AgNP emissions to soils. The objectives of this study were first to determine the uptake kinetics of Ag in mealworms (Tenebrio molitor) and woodlice (Porcellio scaber) exposed to Ag₂S NPs in a mesocosm test, and second, to check if the obtained toxicokinetics could be predicted by single-species bioaccumulation tests. In the mesocosms, mealworms and woodlice were exposed together with plants and earthworms in soil columns spiked with 10 μg Ag g^-1 dry soil as Ag₂S NPs or AgNO₃. The total Ag concentrations in the biota were measured after 7, 14, and 28 days of exposure. A one-compartment model was used to calculate the Ag uptake and elimination rate constants. Ag from Ag₂S NPs appeared to be taken up by the mealworms with significantly different uptake rate constants in the mesocosm compared to single-species tests (K₁ = 0.056 and 1.66 g dry soil g^-1 dry body weight day^-1, respectively), and a significant difference was found for the Ag bioaccumulation factor (BAF_k = 0.79 and 0.15 g dry soil g^-1 dry body weight, respectively). Woodlice did not accumulate Ag from Ag₂S NPs in both tests, but uptake from AgNO₃ was significantly slower in mesocosm than in single-species tests (K₁ = 0.037 and 0.26 g dry soil g^-1 dry body weight day^-1, respectively). Our results are of high significance because they show that single-species tests may not be a good predictor for the Ag uptake in mealworms and woodlice in exposure systems having greater levels of biological complexity. Nevertheless, single-species tests could be used as a fast screening approach to assess the potential of a substance to accumulate in biota before more complex tests are conducted.

Metal transfer to sediments, invertebrates and fish following waterborne exposure to silver nitrate or silver sulfide nanoparticles in an indoor stream mesocosm

The fate of engineered nanomaterials in ecosystems is unclear. An aquatic stream mesocosm explored the fate and bioaccumulation of silver sulfide nanoparticles (Ag₂S NPs) compared to silver nitrate (AgNO₃). The aims were to determine the total Ag in water, sediment and biota, and to evaluate the bioavailable fractions of silver in the sediment using a serial extraction method. The total Ag in the water column from a nominal daily dose of 10 μg L^-1 of Ag for the AgNO₃ or Ag₂S NP treatments reached a plateau of around 13 and 12 μg L^-1, respectively, by the end of the study. Similarly, the sediment of both Ag-treatments reached ~380 μg Ag kg^-1, and with most of it being acid-extractable/labile. The biota accumulated 4-59 μg Ag g^-1 dw, depending on the type of Ag-treatment and organism. The oligochaete worm, Lumbriculus variegatus, accumulated Ag from the Ag₂S exposure over time, which was similar to the AgNO₃ treatment by the end of the experiment. The planarian, Girardia tigrina, and the chironomid larva, Chironomus riparius, showed much higher Ag concentrations than the oligochaete worms; and with a clearer time-dependent statistically significant Ag accumulation relative to the untreated controls. For the pulmonate snail, Physa acuta, bioaccumulation of Ag from AgNO₃ and Ag₂S NP exposures was observed, but was lower from the nano treatment. The AgNO₃ exposure caused appreciable Ag accumulation in the water flea, Daphnia magna, but accumulation was higher in the Ag₂S NP treatment (reaching 59 μg g^-1 dw). In the rainbow trout, Oncorhynchus mykiss, AgNO₃, but not Ag₂S NPs, caused total Ag concentrations to increase in the tissues. Overall, the study showed transfer of total Ag from the water column to the sediment, and Ag bioaccumulation in the biota, with Ag from Ag₂S NP exposure generally being less bioavailable than that from AgNO₃.

Soil Ecotoxicology Needs Robust Biomarkers: A Meta-Analysis Approach to Test the Robustness of Gene Expression-Based Biomarkers for Measuring Chemical Exposure Effects in Soil Invertebrates

Gene expression-based biomarkers are regularly proposed as rapid, sensitive, and mechanistically informative tools to identify whether soil invertebrates experience adverse effects due to chemical exposure. However, before biomarkers could be deployed within diagnostic studies, systematic evidence of the robustness of such biomarkers to detect effects is needed. In our study, we present an approach for conducting a meta-analysis of the robustness of gene expression-based biomarkers in soil invertebrates. The approach was developed and trialed for two measurements of gene expression commonly proposed as biomarkers in soil ecotoxicology: earthworm metallothionein (MT) gene expression for metals and earthworm heat shock protein 70 (HSP70) gene expression for organic chemicals. We collected 294 unique gene expression data points from the literature and used linear mixed-effect models to assess concentration, exposure duration, and species effects on the quantified response. The meta-analysis showed that the expression of earthworm MT was strongly metal concentration dependent, stable over time and species independent. The metal concentration-dependent response was strongest for cadmium, indicating that this gene is a suitable biomarker for this metal. For copper, no clear concentration-dependent response of MT gene expression in earthworms was found, indicating MT is not a reliable biomarker for this metal. For HSP70, overall marginal up-regulation and lack of a concentration-dependent response indicated that this gene is not suitable as a biomarker for organic pollutant effects in earthworms. The present study demonstrates how meta-analysis can be used to assess the status of biomarkers. We encourage colleagues to apply this open-access approach to other biomarkers, as such quantitative assessment is a prerequisite to ensuring that the suitability and limitations of proposed biomarkers are known and stated. Environ Toxicol Chem 2022;41:2124-2138. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Reproducibility of methods required to identify and characterize nanoforms of substances

Nanoforms (NFs) of a substance may be distinguished from one another through differences in their physicochemical properties. When registering nanoforms of a substance for assessment under the EU REACH framework, five basic descriptors are required for their identification: composition, surface chemistry, size, specific surface area and shape. To make the risk assessment of similar NFs efficient, a number of grouping frameworks have been proposed, which often require assessment of similarity on individual physicochemical properties as part of the group justification. Similarity assessment requires an understanding of the achievable accuracy of the available methods. It must be demonstrated that measured differences between NFs are greater than the achievable accuracy of the method, to have confidence that the measured differences are indeed real. To estimate the achievable accuracy of a method, we assess the reproducibility of six analytical techniques routinely used to measure these five basic descriptors of nanoforms: inductively coupled plasma mass spectrometry (ICP-MS), Thermogravimetric analysis (TGA), Electrophoretic light scattering (ELS), Brunauer-Emmett-Teller (BET) specific surface area and transmission and scanning electron microscopy (TEM and SEM). Assessment was performed on representative test materials to evaluate the reproducibility of methods on single NFs of substances. The achievable accuracy was defined as the relative standard deviation of reproducibility (RSD_R) for each method. Well established methods such as ICP-MS quantification of metal impurities, BET measurements of specific surface area, TEM and SEM for size and shape and ELS for surface potential and isoelectric point, all performed well, with low RSD_R, generally between 5 and 20%, with maximal fold differences usually <1.5 fold between laboratories. Applications of technologies such as TGA for measuring water content and putative organic impurities, additives or surface treatments (through loss on ignition), which have a lower technology readiness level, demonstrated poorer reproducibility, but still within 5-fold differences. The expected achievable accuracy of ICP-MS may be estimated for untested analytes using established relationships between concentration and reproducibility, but this is not yet the case for TGA measurements of loss on ignition or water content. The results here demonstrate an approach to estimate the achievable accuracy of a method that should be employed when interpreting differences between NFs on individual physicochemical properties.

Assessing the similarity of nanoforms based on the biodegradation of organic surface treatment chemicals

A substance may have one or more nanoforms, defined for regulatory purposes under EU chemicals legislation REACH based on differences in physicochemical properties such as size, shape, specific surface area and surface chemistry including coatings. To reduce the burden of testing each unique nanoform for the environmental risk assessment of nanomaterials, grouping approaches allow simultaneous assessment of multiple nanoforms. Nanoforms with initially different intrinsic properties, could still be considered similar if their environmental fate and effects can be demonstrated to be similar. One hypothesis to group nanoforms with different organic surface modifications is to use parameters linked to biodegradation of the organic surface. The hypothesis contends that nanoforms with a similar core chemistry, but different organic surface treatments may be grouped, if the surface treatment is likely to be lost through biodegradation rapidly upon entering an environmental compartment, such that it no longer modulates fate, exposure and toxicity of the nanoform. To implement grouping according to surface treatment biodegradability, a robust approach to measure the breakdown of particle surface treatments is needed. We present a tiered testing strategy to assess the biodegradation of organic surface treatments used with nanomaterials that can be implemented as part of an Integrated Approach to Testing and Assessment (IATA) for grouping based on surface treatment stability. The tiered approach consists of an initial pre-screening MT2 colorimetric carbon substrate utilisation assay, to provide a rapid assessment of coating degradation, and a second tier of testing using OECD Test Guideline 301F for assessing organic chemical biodegradability. Six common surface treatment substances are assessed using the tiered testing strategy to refine rules for escalating between tiers. Similarity assessment using absolute Euclidean distances and x-fold difference concluded that the Tier 1 assessment can be used as conservative binary screening for biodegradability (no false positive results in Tier 1), whilst for substances showing intermediate biodegradation (10-60% in OECD 301F, Tier 2), similarity assessments can be informative for grouping surface treatments not considered readily biodegradable. Further validation using higher tier tests (e.g., mesocosms) is needed to define acceptable limits of similarity between intermediately biodegradable substances, where differences in biodegradability of the surface coating lead to negligible differences in fate, behaviour and toxicity of the nanoforms, and this is critically discussed.

Earthworms ingest microplastic fibres and nanoplastics with effects on egestion rate and long-term retention

Microplastic fibres (MPFs) and nanoplastics (NPs) have the potential to be hazardous to soil organisms. Understanding uptake into organisms is key in assessing these effects, but this is often limited by the analytical challenges to quantify smaller-sized plastics in complex matrices. This study used MPFs and NPs containing inorganic tracers (In, Pd) to quantify uptake in the earthworm Lumbricus terrestris. Following seven days exposure, tracer concentrations were measured in earthworms and faeces. Earthworms exposed to 500 μg MPFs/g soil retained an estimated 32 MPFs in their tissues, while at 5000 μg MPFs/g earthworms retained between 2 and 593 MPFs. High variation in body burdens of MPFs was linked to soil retention in earthworms and reduced faeces production, suggesting egestion was being affected by MPFs. NPs uptake and elimination was also assessed over a more extended time-period of 42 days. After 1 day, NPs were no longer detectable in faeces during the elimination phase. However, some retention of NPs in the earthworms was estimated, not linked to retained soil, indicating not all NPs were eliminated. MPFs and NPs uptake can be quantified in earthworms and both particle types can be retained beyond the depuration period, suggesting the potential for longer-term accumulation.

Refinement of the selection of physicochemical properties for grouping and read-across of nanoforms

Before placing a new nanoform (NF) on the market, its potential adverse effects must be evaluated. This may e.g. be done via hazard and risk assessment. Grouping and read-across of NFs is a possible strategy to reduce resource consumption, maximising the use of existing data for assessment of NFs. The GRACIOUS project provides a framework in which possible grouping and read-across for NFs is mainly based on an evaluation of their similarity. The impact of NFs on human health and the environment depends strongly on the concentration of the NF and its physicochemical properties, such as chemical composition, size distribution, shape, etc. Hence, knowledge of the most relevant physicochemical properties is essential information for comparing similarity. The presented work aims to refine existing proposals for sets of descriptors (descriptor array) that are needed to describe distinct NFs of a material to identify the most relevant ones for grouping and read-across. The selection criteria for refining this descriptor array are explained and demonstrated. Relevant protocols and methods are proposed for each physicochemical property. The required and achievable measurement accuracies of the refined descriptor array are reviewed, as this information is necessary for similarity assessment of NFs based on individual physicochemical properties.

How can we justify grouping of nanoforms for hazard assessment? Concepts and tools to quantify similarity

The risk of each nanoform (NF) of the same substance cannot be assumed to be the same, as they may vary in their physicochemical characteristics, exposure and hazard. However, neither can we justify a need for more animal testing and resources to test every NF individually. To reduce the need to test all NFs, (regulatory) information requirements may be fulfilled by grouping approaches. For such grouping to be acceptable, it is important to demonstrate similarities in physicochemical properties, toxicokinetic behaviour, and (eco)toxicological behaviour. The GRACIOUS Framework supports the grouping of NFs, by identifying suitable grouping hypotheses that describe the key similarities between different NFs. The Framework then supports the user to gather the evidence required to test these hypotheses and to subsequently assess the similarity of the NFs within the proposed group. The evidence needed to support a hypothesis is gathered by an Integrated Approach to Testing and Assessment (IATA), designed as decision trees constructed of decision nodes. Each decision node asks the questions and provides the methods needed to obtain the most relevant information. This White paper outlines existing and novel methods to assess similarity of the data generated for each decision node, either via a pairwise analysis conducted property-by-property, or by assessing multiple decision nodes simultaneously via a multidimensional analysis. For the pairwise comparison conducted property-by-property we included in this White paper: The x-fold, Bayesian and Arsinh-OWA distance algorithms performed comparably in the scoring of similarity between NF pairs. The Euclidean distance was also useful, but only with proper data transformation. The x-fold method does not standardize data, and thus produces skewed histograms, but has the advantage that it can be implemented without programming knowhow. A range of multidimensional evaluations, using for example dendrogram clustering approaches, were also investigated. Multidimensional distance metrics were demonstrated to be difficult to use in a regulatory context, but from a scientific perspective were found to offer unexpected insights into the overall similarity of very different materials. In conclusion, for regulatory purposes, a property-by-property evaluation of the data matrix is recommended to substantiate grouping, while the multidimensional approaches are considered to be tools of discovery rather than regulatory methods.

A Kinetic Approach for Assessing the Uptake of Ag from Pristine and Sulfidized Ag Nanomaterials to Plants

Nanomaterials (NMs) are thermodynamically unstable by nature, and exposure of soil organisms to NMs in the terrestrial environment cannot be assumed constant. Thus, steady-state conditions may not apply to NMs, and bioaccumulation modeling for uptake should follow a dynamic approach. The one-compartment model allows the uptake and elimination of a chemical to be determined, while also permitting changes in exposure and growth to be taken into account. The aim of the present study was to investigate the accumulation of Ag from different Ag NM types (20 nm Ag⁰ NMs, 50 nm Ag⁰ NMs, and 25 nm Ag₂ S NMs) in the crop plant wheat (Triticum aestivum). Seeds were emerged in contaminated soils (3 or 10 mg Ag/kg dry soil, nominal) and plants grown for up to 42 d postemergence. Plant roots and shoots were collected after 1, 7, 14, 21, and 42 d postemergence; and total Ag was measured. Soil porewater Ag concentrations were also measured at each sampling time. Using the plant growth rates in the different treatments and the changing porewater concentrations as parameters, the one-compartment model was used to estimate the uptake and elimination of Ag from the plant tissues. The best fit of the model to the data included growth rate and porewater concentration decline, while showing elimination of Ag to be close to zero. Uptake was highest for Ag⁰ NMs, and size did not influence their uptake rates. Accumulation of Ag from Ag₂ S NMs was lower, as reflected by the lower porewater concentrations. Environ Toxicol Chem 2021;40:1861-1872. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Semi-automated analysis of microplastics in complex wastewater samples

In order to assess risks to the natural environment from microplastics, it is necessary to have reliable information on all potential inputs and discharges. This relies on stringent quality control measures to ensure accurate reporting. Here we focus on wastewater treatment works (WwTWs) and the complex sample matrices these provide. Composite samples of both influent and effluent were collected over a 24 h period on two separate occasions from eight different WwTWs across the UK. Sludge samples were taken on five occasions from five WwTWs. The WwTW treatments included activated sludge, trickling filter and biological aerated flooded filter with or without tertiary treatment. Using micro-FTIR analysis, microplastics ≥25 μm were identified and quantified. Procedural blanks were used to derive limits of detection (LOD) and limits of quantification (LOQ). Where values were above the LOQ, microplastics in the influent ranged from 955 to 17,214 microplastic particles/L and in the effluent from 2 to 54 microplastic particles/L, giving an average removal rate of 99.8%. Microplastics could be quantified in sludge at concentrations of 301-10,380 microplastics/g dry weight, this analytical method therefore revealing higher concentrations than reported in previous studies. The most common polymers present overall were polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET). We also report on critical considerations for blank corrections and quality control measures to ensure reliable microplastic analysis across different sample types.

The earthworm microbiome is resilient to exposure to biocidal metal nanoparticles

Environmental pollution can disrupt the interactions between animals and their symbiotic bacteria, which can lead to adverse effects on the host even in the absence of direct chemical toxicity. It is therefore crucial to understand how environmental pollutants affect animal microbiomes, especially for those chemicals that are designed to target microbes. Here, we study the effects of two biocidal nanoparticles (NPs) (Ag and CuO) on the soil bacterial community and the resident gut microbiome of the earthworm Eisenia fetida over a 28-day period using metabarcoding techniques. Exposures to NPs were conducted following OECD test guidelines and effects on earthworm reproduction and juvenile biomass were additionally recorded in order to compare effects on the host to effects on microbiomes. By employing a full concentration series, we were able to link pollutants to microbiome effects in high resolution. Multivariate analysis, differential abundance analysis and species sensitivity distribution analysis showed that Ag-NPs are more toxic to soil bacteria than CuO-NPs. In contrast to the strong effects of CuO-NPs and Ag-NPs on the soil bacterial community, the earthworm gut microbiome is largely resilient to exposure to biocidal NPs. Despite this buffering effect, CuO-NPs did negatively affect the relative abundance of some earthworm symbionts, including 'Candidatus Lumbricincola'. Changes in the soil bacterial community and the earthworm microbiome occur at total copper concentrations often found or modelled to occur in agricultural fields, demonstrating that soil bacterial communities and individual taxa in the earthworm microbiome may be at risk from environmental copper exposure including in nanomaterial form.

Identification and Quantification of Microplastics in Potable Water and Their Sources within Water Treatment Works in England and Wales

Microplastics were characterized in eight water treatment works (WTWs) in England and Wales (UK). Sources included river water, groundwater, and an upland reservoir. Water treatment varied from disinfection, filtration, sedimentation, and activated carbon techniques. At each WTW, five repeat samples of raw and potable water and two repeat sludge samples were taken over 5 months. Microplastics in water were captured on 10 μm filters and nonplastic materials digested in the laboratory. Microplastics ≥25 μm were analyzed using Fourier-transform infrared microscopy. Blanks revealed consistent polyethylene (PE), poly(ethylene terephthalate) (PET), and polypropylene (PP) contamination. Spike recoveries for 63-90 μm polyamide microplastics demonstrated 101% (standard deviation, SD 27%) and 113% (SD 15%) recovery for raw and potable waters and 52% (SD 13%) for sludge. Only four of the six WTWs sampled for raw water and only two of eight WTWs in their potable water had microplastics above the limit of quantification. Considering only the WTWs with quantifiable microplastics, then on average, 4.9 microplastic particles/L were present in raw water and only 0.00011 microplastic particles/L were present in potable water (99.99% removal). Values in waste sludge were highly variable. PE, PET, and PP were the most common polymers quantified in raw water and sludge, and polystyrene and acrylonitrile butadiene styrene were the most common polymers quantified in potable water.

Key principles and operational practices for improved nanotechnology environmental exposure assessment

Nanotechnology is identified as a key enabling technology due to its potential to contribute to economic growth and societal well-being across industrial sectors. Sustainable nanotechnology requires a scientifically based and proportionate risk governance structure to support innovation, including a robust framework for environmental risk assessment (ERA) that ideally builds on methods established for conventional chemicals to ensure alignment and avoid duplication. Exposure assessment developed as a tiered approach is equally beneficial to nano-specific ERA as for other classes of chemicals. Here we present the developing knowledge, practical considerations and key principles need to support exposure assessment for engineered nanomaterials for regulatory and research applications.

The Effects of In Vivo Exposure to Copper Oxide Nanoparticles on the Gut Microbiome, Host Immunity, and Susceptibility to a Bacterial Infection in Earthworms

Nanomaterials (NMs) can interact with the innate immunity of organisms. It remains, however, unclear whether these interactions can compromise the immune functioning of the host when faced with a disease threat. Co-exposure with pathogens is thus a powerful approach to assess the immuno-safety of NMs. In this paper, we studied the impacts of in vivo exposure to a biocidal NM on the gut microbiome, host immune responses, and susceptibility of the host to a bacterial challenge in an earthworm. Eisenia fetida were exposed to CuO-nanoparticles in soil for 28 days, after which the earthworms were challenged with the soil bacterium Bacillus subtilis. Immune responses were monitored by measuring mRNA levels of known earthworm immune genes. Effects of treatments on the gut microbiome were also assessed to link microbiome changes to immune responses. Treatments caused a shift in the earthworm gut microbiome. Despite these effects, no impacts of treatment on the expression of earthworm immune markers were recorded. The methodological approach applied in this paper provides a useful framework for improved assessment of immuno-safety of NMs. In addition, we highlight the need to investigate time as a factor in earthworm immune responses to NM exposure.

A standardised bioassay method using a bench-top spray tower to evaluate entomopathogenic fungi for control of the greenhouse whitefly, Trialeurodes vaporariorum

BACKGROUND

Bioassays evaluating entomopathogenic fungi (EPF) isolates for effective microbial control of whitefly are a fundamental part of the screening process for bioprotectants, but development of repeatable, robust bioassays is not straightforward. Currently, there is no readily available standardised method to test the efficacy of EPF on whitefly. Here, we describe the calibration and use of a spray tower to deliver a standardised protocol to assess EPF activity; the method was validated using 18 EPF from four genera in tests against greenhouse whitefly, Trialeurodes vaporariorum (Westwood).

RESULTS

At 138 kPa, the sprayer delivered 0.062 mL mm^-2 (620 L ha^-1 ) and an even deposition of spray across the central 1590 mm² of the spray area. Average conidial deposition for all EPF was 252 conidia mm^-2 and equivalent to 2.5 × 10¹² conidia ha^-1 at an application concentration of 1 × 10⁷ conidia mL^-1 . Conidial deposition of a test Beauveria bassiana suspension increased with increasing application concentration. Egg laying by T. vaporariorum adults was restricted to 177 mm² using clip cages specifically designed to ensure that third-instar T. vaporariorum received a uniform spray coverage. Nymphs occupied 373 ± 5 mm² of the leaf after migrating during the first instar. Average T. vaporariorum mortality totaled 8-89% 14 days after application of 1 × 10⁷ conidia mL^-1 of each EPF isolate.

CONCLUSION

Combining the calibrated sprayer and bioassay method provides a reliable, standardised approach to test the virulence of EPF against whitefly nymphs. This laboratory-based assay is affordable, replicable and allows the user to alter the dose of conidia applied to the target.

Addressing Nanomaterial Immunosafety by Evaluating Innate Immunity across Living Species

The interaction of a living organism with external foreign agents is a central issue for its survival and adaptation to the environment. Nanosafety should be considered within this perspective, and it should be examined that how different organisms interact with engineered nanomaterials (NM) by either mounting a defensive response or by physiologically adapting to them. Herein, the interaction of NM with one of the major biological systems deputed to recognition of and response to foreign challenges, i.e., the immune system, is specifically addressed. The main focus is innate immunity, the only type of immunity in plants, invertebrates, and lower vertebrates, and that coexists with adaptive immunity in higher vertebrates. Because of their presence in the majority of eukaryotic living organisms, innate immune responses can be viewed in a comparative context. In the majority of cases, the interaction of NM with living organisms results in innate immune reactions that eliminate the possible danger with mechanisms that do not lead to damage. While in some cases such interaction may lead to pathological consequences, in some other cases beneficial effects can be identified.

NanoSolveIT Project: Driving nanoinformatics research to develop innovative and integrated tools for in silico nanosafety assessment

Nanotechnology has enabled the discovery of a multitude of novel materials exhibiting unique physicochemical (PChem) properties compared to their bulk analogues. These properties have led to a rapidly increasing range of commercial applications; this, however, may come at a cost, if an association to long-term health and environmental risks is discovered or even just perceived. Many nanomaterials (NMs) have not yet had their potential adverse biological effects fully assessed, due to costs and time constraints associated with the experimental assessment, frequently involving animals. Here, the available NM libraries are analyzed for their suitability for integration with novel nanoinformatics approaches and for the development of NM specific Integrated Approaches to Testing and Assessment (IATA) for human and environmental risk assessment, all within the NanoSolveIT cloud-platform. These established and well-characterized NM libraries (e.g. NanoMILE, NanoSolutions, NANoREG, NanoFASE, caLIBRAte, NanoTEST and the Nanomaterial Registry (>2000 NMs)) contain physicochemical characterization data as well as data for several relevant biological endpoints, assessed in part using harmonized Organisation for Economic Co-operation and Development (OECD) methods and test guidelines. Integration of such extensive NM information sources with the latest nanoinformatics methods will allow NanoSolveIT to model the relationships between NM structure (morphology), properties and their adverse effects and to predict the effects of other NMs for which less data is available. The project specifically addresses the needs of regulatory agencies and industry to effectively and rapidly evaluate the exposure, NM hazard and risk from nanomaterials and nano-enabled products, enabling implementation of computational 'safe-by-design' approaches to facilitate NM commercialization.

Predicting acute contact toxicity of organic binary mixtures in honey bees (A. mellifera) through innovative QSAR models

Pollinators such as honey bees are of considerable importance, because of the crucial pollination services they provide for food crops and wild plants. Since bees are exposed to a wide range of multiple chemicals "mixtures" both of anthropogenic (e.g. plant protection products) and natural origin (e.g. plant toxins), understanding their combined toxicity is critical. Although honey bees are employed worldwide as surrogate species for Apis and non-Apis bees in toxicity tests, it is practically unfeasible to perform in vivo tests for all mixtures of chemicals. Therefore, Quantitative Structure-Activity Relationships (QSAR) models can be developed using available data and can provide useful tools to predict such combined toxicity. Here, three different QSAR models within the CORAL software have been calibrated and validated for honey bees (A. mellifera) to predict the acute contact mixtures potency (LD_50-mix), in two regression based-models, and the nature of combined toxicity (synergism / non-synergism) in a classification-based model. Experimental data on binary mixtures (n = 123) (LD_50-mix) including dose response data (n = 97) and corresponding Toxic Unit values were retrieved from EFSA databases. The models were built using the principle of extraction of attributes from SMILES (or quasi-SMILES) while calculating so-called correlation weights for these attributes using Monte Carlo techniques. The two regression models were validated for their reliability and robustness (R² = 0.89, CCC = 0.92, Q² = 0.81; R² = 0.87, CCC = 0.89, Q² = 0.75). The classification model was validated using sensitivity (=0.86), specificity (=1), accuracy (=0.96), and Matthews correlation coefficient (MCC = 0.90) as qualitative statistical validation parameters. Results indicate that these QSAR models successfully predict acute contact toxicity of binary mixtures in honey bees and can support prioritisation of multiple chemicals of concerns. Data gaps and further development of QSAR models for honey bees are highlighted particularly for chronic and sub-lethal effects.