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Sewage sludge applications as soil amendment call for a proper ecological risk assessment due to unexpected delivery of toxic chemicals and materials. Standardized acute toxicity assays have proven to provide limited information in terms of potential hazard for soil organisms. Here, sublethal endpoints as physiological and tissue alterations were proposed as suitable tools for sewage sludge ecological risk assessment. Acute toxicity assay using earthworm Eisenia fetida (OECD n.207) was performed on sewage sludge samples from two wastewater treatment plants (A and B), and mortality, body weight, body morphology, and histology of intestinal cavity were evaluated at the end of the exposure period. Sewage sludge dilutions (1:50 and 1:100) from plant B caused a low percentage of mortality (5%), while none was observed in worms exposed to plant A. However, all specimens showed external body alterations as vesicles, swellings, constrictions, and discoloration. Histological sections highlight damages to epidermis, circular and longitudinal muscles, and chloragogenic tissue regardless of sewage sludge origin. Our findings confirm that standardized end points of acute toxicity are not sensitive enough in worms exposed to sewage sludges, while sublethal endpoints as body morphology and tissue histology are thus more suitable and appropriate endpoints for assessing potential detrimental outcomes and ecological risk for soil biota., Competing Interests: Declarations. Ethical approval: Not applicable. Consent to participate: Not applicable. Consent for publication: All authors agreed with the content, all gave explicit consent to submit, and they obtained consent from the responsible authorities at the institute where the work has been carried out. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Soil sorption properties can influence the bioavailability of substances and consequently the toxicity for soil organisms. Current standardised laboratory testing for the exposure assessment of pesticides to soil organisms uses OECD artificial soil that does not reflect the high variation in chemical-physical soil properties found in natural agroecosystems. According to guideline OECD 222, earthworm reproduction tests with Eisenia fetida and the pesticide carbendazim were performed in four natural soils and OECD artificial soil. By using pF 1.6, which ensures a uniformity in actual soil water availability, the control reproduction performance of E. fetida in all natural soils was at the same level as OECD artificial soil. In a principle component analysis, the variation in toxicity between the tested soils was attributable to a combination of two soil properties, namely total organic carbon content (TOC) and pH. The largest difference of 4.9-fold was found between the typical agricultural Luvisol with 1.03% TOC and pH 6.2 (EC10: 0.17 (0.12–0.21) mg a.i. kg−1 sdw, EC50: 0.36 (0.31–0.40) mg a.i. kg−1 sdw) and OECD artificial soil with 4.11% TOC and pH 5.6 (EC10: 0.84 (0.72–0.92) mg a.i. kg−1 sdw, EC50: 1.07 (0.99–1.15) mg a.i. kg−1 sdw). The use of typical agricultural soils in standardised laboratory earthworm testing was successfully established with using the measure pF for soil moisture adjustment. It provides a more application-oriented approach and could serve as a new tool to refine the environmental risk assessment at lower tier testing or in an intermediate tier based approach. [ABSTRACT FROM AUTHOR]

Among engineered nanomaterials, CeO2 nanoparticles (NPs) are of particular interest due to their unique properties. These NPs' anti-oxidative and auto-reduction natures also render them promising in scavenging reactive oxygen species (ROS). In this study, different synthesis methods of CeO2 NPs were studied: an NH4OH precipitation method, a NaOH precipitation method, and a microwave hydrothermal synthesis. Among these methods, the one-pot facile NH4OH method outperformed the others. The synthesized CeO2 NPs were determined to be highly monodispersed 13 nm crystallites with a pH at the potential of zero point charge (pHzpc) of 2.2. The valence states of Ce in CeO2 NPs were 3 + and 4 + were determined. The synthesized CeO2 NPs remained stable over 2 days in a medium containing FBS and over 3 days in NaCl solutions. The auto-reduction oxidation cycles of our CeO2 NPs were able to scavenge ROS multiple times. The cytotoxicity of NPs showed CeO2 NPs did not have a significant toxic effect on neuro2A cells. Owing to its synthesis of NPs of small size, with anti-oxidative/auto-reduction nature, with stability in cell culture media, and an absence of cytotoxicity toward neuroblastoma cells, this novel method proves promising as a method to generate CeO2 NPs for biomedical applications. [ABSTRACT FROM AUTHOR]

The impact of soil lead (Pb) pollution on survival, growth, and reproduction of the collembolan, Folsomia candida, and Pb compartmentation in its gut and remaining body parts were studied by exposing animals to laboratory-spiked soil. The survival, growth, and reproduction of F. candida were significantly reduced by increasing soil Pb concentration. The LC50 values of survival based on total and CaCl2-extractable Pb concentration in soil were 2562 mg kg−1 and 351 mg kg−1, respectively. The EC50 values of reproduction were 1244 mg kg−1 and 48 mg kg−1, respectively. The Pb concentration in whole body, gut, and remaining body parts was significantly increased with the increase of soil Pb concentration and followed an exponential increase when the soil Pb concentration was equal to or above a threshold (1000 mg kg−1 for whole body and remaining body part, 500 mg kg−1 for gut). Below this threshold, these relationships were linear. The Pb concentration in the gut was higher than whole body and remaining body part of F. candida, and the threshold of internal Pb concentration at which F. candida can compensate was in the range 7–13 mg Pb kg−1 dry animal (corresponding to soil Pb concentration 500–1000 mg Pb kg−1 dry soil). The results indicate that reproduction of F. candida was a more sensitive indicator of lead toxicity than survival and growth. Pb was mainly accumulated in the gut of F. candida. We discuss the internal Pb concentration as an indicator of adverse effects in the risk assessment of soil Pb pollution. [ABSTRACT FROM AUTHOR]

Major concerns exist regarding the environmental and human health risks caused by exposure to heavy metals. Spiders are often used as a model in ecotoxicological studies to assess soil pollution. Here, we measured the bioaccumulation of copper (Cu) and lead (Pb) in spiders, Lycosa terrestris and Pardosa birmanica, by inductively coupled plasma mass spectrometry (ICP-MS). We investigated whether Cu and Pb accumulation differs according to different spider species, single versus combined metal exposure, and routes of exposure. Spiders were exposed to 10 mM CuSO4 and 10 mM PbCl2 solutions separately or in combination (10 mM + 10 mM) through different exposure routes (spiked soil and food) for 6 weeks. The effect of metals on the survival and body mass of exposed and unexposed (control) spiders was determined. We found that in both spider species, accumulation of metals increased with exposure time. In single metal exposure, Cu accumulation from food was higher than soil exposure in both spider species, whereas the opposite was observed for Pb. The simultaneous uptake of Cu and Pb significantly decreased from food and soil, respectively. Soil exposure caused more accumulation of metals in L. terrestris than P. birmanica. Metal exposure via contaminated food caused higher mortality compared to soil exposure. Body mass of both spider species was significantly decreased and negatively correlated with metal's concentration. Overall, our results show that bioaccumulation efficiency of Cu and Pb differs significantly in spiders exposed to metal's mixture compared to single metal exposure and is dependent on the exposure route, the type of metal, and spider species. More understanding of the effects of exposure to metal mixture and exposure routes is essential for designing and supporting risk assessment and ecological monitoring programs. [ABSTRACT FROM AUTHOR]

At the global scale, urban agriculture is increasingly developing in cities due to demographic growth and sustainable food concerns. But, urban soils are frequently polluted with metals. In urban gardens, organic matter is also commonly added both to valorize organic household waste and to promote biophysicochemical fertility. As earthworms promote the decomposition and the recycling of soil organic matter, they can also influence the biogeochemical cycle of metals in urban polluted soils. In order to produce safe vegetables in urban areas, it is crucial to highlight the mechanisms involved in complex soil-earthworm-plant ecosystems. An experiment was set up to examine these relationships using lettuce cultivated in controlled conditions with RHIZOtest® devices. Thanks to the RHIZOtest® devices, metal transfer and bioaccessibility were for the first time compared for urban polluted soil without (1—urban soil polluted with Pb, Cd, Cu, and Zn: essential or toxic metals currently found in environment, SNB) and with bioturbation (2—this metal-polluted soil subjected to earthworm bioturbation, SB) and earthworm casts (3—earthworm casts produced in this polluted soil and naturally enriched in organic matter and microorganisms, T). Metal concentration, phytoavailability, and human gastric bioaccessibility were determined in the different samples. Results showed that earthworm bioturbation increased the phytoavailability of all the metals. For the experimental condition SB, the phytoavailability of metals was increased up to 75% compared to SNB. In addition, surprisingly, metal phytoavailability was always superior in SB compared to earthworm casts (T). Moreover, earthworms led to an increase in Zn gastric bioaccessibility up to 10% in the soils in the same way as for phytoavailability, meaning Zn bioaccessibility in SB > T > SNB, whereas it remained unchanged in the lettuces. These data are important to promote sustainable agriculture activities in urban areas; actually, databases concerning different experimental conditions are needed to develop decision support tools. [ABSTRACT FROM AUTHOR]

Abstract: Comprehensive experimental quantification and mapping of the aggregation and dispersion state of engineered nanoparticles (NPs) in the presence of humic substances is a great challenge. Dissipative particle dynamic (DPD) simulation was adopted to investigate the aggregation and dispersion mechanisms of NPs in the presence of a humic substance analog. Twelve different types of NPs including 2 metal‐based NPs, 7 metal oxide‐based NPs, and 3 carbon‐based NPs in pure water (pH 3.0) and algae medium (pH 8.0) in the presence of a humic substance analogy were selected for experimental verification of the DPD simulation results. In agreement with results obtained with dynamic light scattering and phase analysis light scattering techniques, the simulations demonstrated that the presence of humic substances reduced the aggregation extent of the NPs. The DPD simulations showed that the stability and dispersity of the NPs increased first, and then decreased with increasing concentrations of humic substances. Moreover, there existed a concentration of humic substances where the NPs became more stable and more dispersed, which was experimentally verified in the case of all the NPs in the pure water and in the algae medium. Furthermore, theory and simulation indicate that both hydrophobic and hydrogen interaction play an important role in controlling the formation of NP aggregates in the presence of humic substances. Electrostatic interaction and steric repulsion are the main mechanisms underlying the effects of humic substances on the aqueous dispersion stability of NPs. Environ Toxicol Chem 2018;37:1024–1031. © 2017 SETAC [ABSTRACT FROM AUTHOR]

The effect of dissolved organic matter (DOM) on nanoparticle toxicity to plants is poorly understood. In this study, tannic acid (TA) was selected as a DOM surrogate to explore the mechanisms of neodymium oxide NPs (Nd2O3NPs) phytotoxicity to pumpkin (Cucurbita maxima). The results from the tested concentrations showed that 100 mg L−1Nd2O3NPs were significantly toxic to pumpkin in term of fresh biomass, and the similar results from the bulk particles and the ionic treatments were also evident. Exposure to 100 mg L−1of Nd2O3NPs and BPs in 1/5 strength Hoagland’s solution not only significantly inhibited pumpkin growth, but also decreased the S, Ca, K and Mg levels in plant tissues. However, 60 mg L−1TA significantly moderated the observed phytotoxicity, decreased Nd accumulation in the roots, and notably restored S, Ca, K and Mg levels in NPs and BPs treated pumpkin. TA at 60 mg L−1increased superoxide dismutase (SOD) activity in both roots (17.5%) and leaves (42.9%), and catalase (CAT) activity (243.1%) in the roots exposed to Nd2O3NPs. This finding was confirmed by the observed up-regulation of transcript levels of SOD and CAT in Nd2O3NPs treated pumpkin analyzed by quantitative reverse transcription polymerase chain reaction. These results suggest that TA alleviates Nd2O3BPs/NPs toxicity through alteration of the particle surface charge, thus reducing the contact and uptake of NPs by pumpkin. In addition, TA promotes antioxidant enzymatic activity by elevating the transcript levels of genes involved in ROS scavenging. Our results shed light on the mechanisms underlying the influence of DOM on the bioavailability and toxicity of NPs to terrestrial plants. [ABSTRACT FROM AUTHOR]

Effects of benzoic acid (BA) on physicochemical properties and ecotoxicities of CuO nanoparticles (CuONPs) in model aqueous media were studied. The CuONPs had larger hydrodynamic sizes and higher surface zeta potentials during 96 h of settling in the presence of BA than when the BA were not present. BA interaction with CuONPs is shown to promote dissolved Cu release from CuONPs in a dose-dependent manner. The contribution of free Cu-ions to growth inhibition toxicity of the CuONP suspensions at a toxicologically relevant concentration for the green alga Scenedesmus obliquus was around 22 %, indicating that dissolved fraction was not the major source of toxicity of CuONPs. The toxicity of CuONPs increased as the BA concentration increased. BA significantly altered total antioxidant capacity of CuONPs-exposed algal cells. The mechanism of the BA effect on the CuONPs toxicity may be mainly associated with degree of agglomeration, dissolved Cu, and particle-induced oxidative stress. [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) entering water systems are an emerging concern as NPs are more frequently manufactured and used. Single particle inductively coupled plasma-mass spectrometry (SP-ICP-MS) methods were validated to detect Zn- and Ce-containing NPs in surface and drinking water using a short dwell time of 0.1 ms or lower, ensuring precision in single particle detection while eliminating the need for sample preparation. Using this technique, information regarding NP size, size distribution, particle concentration, and dissolved ion concentrations was obtained simultaneously. The fates of Zn- and Ce-NPs, including those found in river water and added engineered NPs, were evaluated by simulating a typical drinking water treatment process. Lime softening, alum coagulation, powdered activated carbon sorption, and disinfection by free chlorine were simulated sequentially using river water. Lime softening removed 38-53 % of Zn-containing and ZnO NPs and >99 % of Ce-containing and CeO NPs. Zn-containing and ZnO NP removal increased to 61-74 % and 77-79 % after alum coagulation and disinfection, respectively. Source and drinking water samples were collected from three large drinking water treatment facilities and analyzed for Zn- and Ce-containing NPs. Each facility had these types of NPs present. In all cases, particle concentrations were reduced by a minimum of 60 % and most were reduced by >95 % from source water to finished drinking water. This study concludes that uncoated ZnO and CeO NPs may be effectively removed by conventional drinking water treatments including lime softening and alum coagulation. [ABSTRACT FROM AUTHOR]

Knowledge of the interaction between graphene-based materials and low-molecular-weight organic acids (LOAs) is essential to understand fate and effects of graphene-based materials in the aquatic environment, but this interaction remains poorly elucidated. In this study, the effects of LOAs on the physicochemical properties of graphene nanoplatelets (GNPs) in an aqueous medium and on the GNP toxicity to algae were studied. The unicellular green alga Scenedesmus obliquus was exposed to GNP suspensions in the presence of benzoic acid or gallic acid at various concentrations. The GNPs had smaller hydrodynamic sizes and the GNP suspensions were more stable and had higher or lower surface zeta potentials in the presence of LOAs than when LOAs were not present. The toxic effects in S. obliquus cultures incubated with GNP suspensions containing LOAs were related to the LOA concentration, and the presence of LOAs caused three effects: stimulation, alleviation, and synergistic inhibition. The intensities of the effects mainly correlated with the LOA concentration, the extent of agglomeration, and particle-induced oxidative stress. The results indicate that the environmental fates and toxicities of GNPs are strongly affected by the binding of GNPs to LOAs. [ABSTRACT FROM AUTHOR]

The present study investigated how humic substances (HS) modify the aquatic toxicity of silver nanoparticles (AgNPs) as these particles agglomerate in water and interact with HS. An alga species ( Raphidocelis subcapitata), a cladoceran species ( Chydorus sphaericus), and a freshwater fish larva ( Danio rerio), representing organisms of different trophic levels, were exposed to colloids of the polyvinylpyrrolidone-coated AgNPs in the presence and absence of HS. Results show that the presence of HS alleviated the aquatic toxicity of the AgNP colloids to all the organisms in a dose-dependent manner. The particle size distribution of the AgNPs' colloidal particles shifted to lower values due to the presence of HS, implying that the decrease in the toxicity of the AgNP colloids cannot be explained by the variation of agglomeration size. The surface charge of the AgNPs was found to be more negative in the presence of high concentrations of HS, suggesting an electrostatic barrier by which HS might limit interactions between particles and algae cells; indeed, this effect reduced the algae toxicity. Observations on silver ions (Ag+) release show that HS inhibit AgNP dissolution, depending on the concentrations of HS. When toxic effects were expressed as a function of each Ag-species, toxicity of the free Ag+ was found to be much higher than that of the agglomerated particles. Environ Toxicol Chem 2015;34:1239-1245. © 2015 SETAC [ABSTRACT FROM AUTHOR]

The cerium dioxide nanoparticle (CeO2 NP) (122 nm) aggregation process was investigated by nanoparticle tracking analysis (NTA), and the results were compared with those of dynamic light scattering (DLS). Unlike descriptions based on classical aggregation kinetics theory, the size distributions obtained by NTA and DLS show that aggregation of NPs in an aquatic environment is a complicated process and highly dependent on the particle number concentration, which is information that has been rarely presented in the literature. In particular, not all the particles were aggregated and there still remained some small CeO2 NPs (< 400 nm), which has potential adverse environmental risks to the ecosystem and public health. Furthermore, the aggregate sizes are far smaller than previously shown in aggregation kinetics experiments. In addition, our findings also indicate that NTA can measure samples with mass concentrations ranging from 0.1 to 100 mg/L without dilution. In contrast, DLS cannot provide accurate information about aggregation kinetics when the mass concentration of CeO2 NPs is lower than 1 mg/L (2.02 × 108 ± 1.66 × 107 by NTA data). Consequently, the classical aggregation kinetics experiment using DLS cannot accurately reflect the fate of NPs in aquatic environment, especially the heteroaggregation of NPs in complex water phase, and these results further demonstrate that the toxicity evaluation of NPs concerning different sizes measured by DLS need more rigorously experimental design. Therefore, our findings provide the first quantitative attempt to explore the experimental conditions and analytical methods for further study of aggregation kinetics. [ABSTRACT FROM AUTHOR]

Background: Particles and fibres affect human health as a function of their properties such as chemical composition, size and shape but also depending on complex interactions in an organism that occur at various levels between particle uptake and target organ responses. While particulate pollution is one of the leading contributors to the global burden of disease, particles are also increasingly used for medical purposes. Over the past decades we have gained considerable experience in how particle properties and particle-bio interactions are linked to human health. This insight is useful for improved risk management in the case of unwanted health effects but also for developing novel medical therapies. The concepts that help us better understand particles' and fibres' risks include the fate of particles in the body; exposure, dosimetry and dose-metrics and the 5 Bs: bioavailability, biopersistence, bioprocessing, biomodification and bioclearance of (nano)particles. This includes the role of the biomolecule corona, immunity and systemic responses, non-specific effects in the lungs and other body parts, particle effects and the developing body, and the link from the natural environment to human health. The importance of these different concepts for the human health risk depends not only on the properties of the particles and fibres, but is also strongly influenced by production, use and disposal scenarios. Conclusions: Lessons learned from the past can prove helpful for the future of the field, notably for understanding novel particles and fibres and for defining appropriate risk management and governance approaches. [ABSTRACT FROM AUTHOR]