Toxicity of ZnO nanoparticles, ZnO bulk, and ZnCl₂ on earthworms in a spiked natural soil and toxicological effects of leachates on aquatic organisms

Ecological Risk Assessment of Three Pesticide Additives in Soil and Application to the Remediation of Contaminated Soil

Pesticide additives (PAs) are auxiliary ingredients added to the pesticide manufacturing and use processes, constituting 1% to 99% of the pesticide and often composed of benzene and chlorinated hydrocarbons. We selected three typical PAs, toluene, chloroform, and trichloroethylene, to evaluate their retention function toxicity and ecological risk in soil. Soil immobilization techniques and aquatic model organisms were used to demonstrate the effectiveness of the immobilized soil method to determine the ecological risk of chemicals. The 48-h median lethal concentrations of toluene, chloroform, and trichloroethylene alone in spiked soil on Daphnia magna were 10.5, 2.3, and 1.1 mg/L (medium, high, and high toxicity, respectively). The toxicity of the three-PA mixtures showed an antagonistic effect. The risk levels of toluene, chloroform, and trichloroethylene in the soil were evaluated as moderate to high, low to high, and high risk, respectively. The toxicity of two pesticide-contaminated sites in the Yangtze River Delta before and after remediation was successfully evaluated by immobilized soil technology. The toxicity of two soil sampling points was reduced from medium toxic to low toxic and no toxic, respectively, after remediation. The results of our study give a rationale for and prove the validity of the aquatic model organisms and soil immobilization techniques in assessing the soil retention functions toxicity of PAs. Environ Toxicol Chem 2024;43:1677-1689. © 2024 SETAC.

Reproductive toxicity perspectives of nanoparticles: an update

INTRODUCTION

The rapid development of nanotechnologies with their widespread prosperities has advanced concerns regarding potential health hazards of the Nanoparticles.

RESULTS

Nanoparticles are currently present in several consumer products, including medications, food, textiles, sports equipment, and electrical components. Despite the advantages of Nanoparticles, their potential toxicity has negative impact on human health, particularly on reproductive health.

CONCLUSIONS

The impact of various NPs on reproductive system function is yet to be determined. Additional research is required to study the potential toxicity of various Nanoparticles on reproductive health. The primary objective of this review is to unravel the toxic effects of different Nanoparticles on the human reproductive functions and recent investigations on the reproductive toxicity of Nanoparticles both in vitro and in vivo.

A Comprehensive Ecotoxicity Study of Molybdenum Disulfide Nanosheets versus Bulk form in Soil Organisms

The increasing use of molybdenum disulfide (MoS2) nanoparticles (NPs) raises concerns regarding their accumulation in soil ecosystems, with limited studies on their impact on soil organisms. Study aim: To unravel the effects of MoS2 nanosheets (two-dimensional (2D) MoS2 NPs) and bulk MoS2 (156, 313, 625, 1250, 2500 mg/kg) on Enchytraeus crypticus and Folsomia candida. The organisms' survival and avoidance behavior remained unaffected by both forms, while reproduction and DNA integrity were impacted. For E. crypticus, the individual endpoint reproduction was more sensitive, increasing at lower concentrations of bulk MoS2 and decreasing at higher ones and at 625 mg/kg of 2D MoS2 NPs. For F. candida, the molecular endpoint DNA integrity was more impacted: 2500 mg/kg of bulk MoS2 induced DNA damage after 2 days, with all concentrations inducing damage by day 7. 2D MoS2 NPs induced DNA damage at 156 and 2500 mg/kg after 2 days, and at 1250 and 2500 mg/kg after 7 days. Despite affecting the same endpoints, bulk MoS2 induced more effects than 2D MoS2 NPs. Indeed, 2D MoS2 NPs only inhibited E. crypticus reproduction at 625 mg/kg and induced fewer (F. candida) or no effects (E. crypticus) on DNA integrity. This study highlights the different responses of terrestrial organisms to 2D MoS2 NPs versus bulk MoS2, reinforcing the importance of risk assessment when considering both forms.

Environmental effects and interaction of nanoparticles on beneficial soil and aquatic microorganisms

A steadily increasing production volume of nanoparticles reflects their numerous industrial and domestic applications. These economic successes come with the potential adverse effects on natural systems that are associated with their presence in the environment. Biological activities and effects of nanoparticles are affected by their entry method together with their specificities like their size, shape, charge, area, and chemical composition. Particles can be classified as safe or dangerous depending on their specific properties. As both aquatic and terrestrial systems suffer from organic and inorganic contamination, nanoparticles remain a sink for these contaminants. Researching the sources, synthesis, fate, and toxicity of nanoparticles has advanced significantly during the last ten years. We summarise nanoparticle pathways throughout the ecosystem and their interactions with beneficial microorganisms in this research. The prevalence of nanoparticles in the ecosystem causes beneficial microorganisms to become hazardous to their cells, which prevents the synthesis of bioactive molecules from undergoing molecular modifications and diminishes the microbe population. Recently, observed concentrations in the field could support predictions of ambient concentrations based on modeling methodologies. The aim is to illustrate the beneficial and negative effects that nanoparticles have on aqueous and terrestrial ecosystems, as well as the methods utilized to reduce their toxicity.

Environmental hazards of WELGRO® Cu+Zn: A nano-enabled fertilizer

Nanoagrochemicals have the potential to revolutionize agriculture towards a precision farming system, able to reduce application rates and consequently their environmental footprint, while keeping efficacy. Several nanoagrochemicals (including nanopesticides (Npes) and nanofertilizers (Nfer)) are already commercialized but the environmental risk assessment of these advanced materials is often lacking. In the present study, we studied the commercial fertilizer WELGRO® Cu + Zn and assessed its ecotoxicity to the soil invertebrate species Enchytraeus crypticus (Oligochaeta), further comparing it to its individual active substances CuO and ZnO. To get a comprehensive picture of possible effects, we used four types of highly relevant tests in LUFA 2.2 soil: 1) avoidance behaviour (2 days), 2) reproduction (OECD standard, 28 d), 3) its extension (56 d), and 4) the full life cycle (FLC) (46 d) - this high level of hazard screening allows for increased interpretation. The results confirmed the nano-features of WELGRO® and a higher toxicity than the mixture of the individual components CuO + ZnO. E. crypticus avoided the soil spiked with WELGRO® and CuO + ZnO, this being the most sensitive endpoint - avoidance behaviour. Both WELGRO® and the active substances were little to non-toxic based on the OECD standard test. However, the toxicity dramatically increased in the tests focussing on longer-term sustainability measures, i.e., 56 days, ca. 170 for WELGRO®. This seems related to the nano-features of WELGRO®, e.g., slow release of ions from the nanoparticles throughout time. The FLCt results showed WELGRO® affected hatching and juveniles' survival, being these the most sensitive life stages. Hence, under actual real world field usage scenarios, i.e., based on the recommended application rates, nanoenabled WELGRO® can affect oligochaete populations like enchytraeids, both via the immediate avoidance behaviour and also via prolonged exposure periods.

Salinity Moderated the Toxicity of Zinc Oxide Nanoparticles (ZnO NPs) towards the Early Development of Takifugu obscurus

ZnO nanoparticles (ZnO NPs) have been applied in a wide range of fields due to their unique properties. However, their ecotoxicological threats are reorganized after being discharged. Their toxic effect on anadromous fish could be complicated due to the salinity fluctuations during migration between freshwater and brackish water. In this study, the combined impact of ZnO NPs and salinity on the early development of a typical anadromous fish, obscure puffer (Takifugu obscurus), was evaluated by (i) observation of the nanoparticle characterization in salt solution; (ii) quantification of the toxicity to embryos, newly hatched larvae, and larvae; and (iii) toxicological analysis using biomarkers. It is indicated that with increased salinity level in brackish water (10 ppt), the toxicity of ZnO NPs decreased due to reduced dissolved Zn2+ content, leading to higher hatch rate of embryos and survival rate of larvae than in freshwater (0 ppt). The irregular antioxidant enzyme activity changes are attributed to the toxic effects of nanoparticles on CAT (catalase), but further determination is required. The results of present study have the significance to guide the wildlife conservation of Takifugu obscurus population.

Impact on Some Soil Physical and Chemical Properties Caused by Metal and Metallic Oxide Engineered Nanoparticles: A Review

In recent years, the release of metal and metallic oxide engineered nanoparticles (ENPs) into the environment has generated an increase in their accumulation in agricultural soils, which is a serious risk to the ecosystem and soil health. Here, we show the impact of ENPs on the physical and chemical properties of soils. A literature search was performed in the Scopus database using the keywords ENPs, plus soil physical properties or soil chemical properties, and elements availability. In general, we found that the presence of metal and metallic oxide ENPs in soils can increase hydraulic conductivity and soil porosity and reduce the distance between soil particles, as well as causing a variation in pH, cation exchange capacity (CEC), electrical conductivity (EC), redox potential (Eh), and soil organic matter (SOM) content. Furthermore, ENPs or the metal cations released from them in soils can interact with nutrients like phosphorus (P) forming complexes or precipitates, decreasing their bioavailability in the soil solution. The results depend on the soil properties and the doses, exposure duration, concentrations, and type of ENPs. Therefore, we suggest that particular attention should be paid to every kind of metal and metallic oxide ENPs deposited into the soil.

A review on sources of heavy metals, their toxicity and removal technique using physico-chemical processes from wastewater

The world is facing environmental pollution and is in an alarming situation due to industrialization and urbanization. Especially, industrial wastewater discharge is causing serious pollution in the environment (water, soil, and air) and has become a challenge for researchers and scientists. Wastewater contains heavy metals like Cu, Ni, Cr, Pb, and Ar and causes toxicity in living beings and the environment. In this review, the sources of heavy metals and their toxicological effects on the environment have been reviewed. Various remediation techniques such as reverse osmosis, chemical precipitation, and ultrafiltration are being used for the treatment of wastewater, but still are limited in their efficiencies, residues, cost, and versatility. In this study, the most promising wastewater treatment technique, the physic-chemical technique, has been reviewed along with its working mechanism and efficiency. Further, the pros and cons of this technique and sub-techniques have also been reviewed to provide a basic understanding to beginners and a pathway to experts in the selection of better techniques.

Extraction and quantification of metal-containing nanoparticles in marine shellfish based on single particle inductively coupled plasma-mass spectrometry technique

Quantitative characterization of nanoparticles (NPs) in marine shellfish is critical to understanding the risks of bio-accumulation. Based on single particle (sp)ICP-MS and electron microscopy, a standardized protocol was developed to extract Ag, Au, and indigenous Ti-containing NPs from mussels. The optimal parameters are: dry sample extraction with tetramethylammonium hydroxide (TMAH), 5% (v/v) final concentration of TMAH, extraction at 25 ℃ for 12 h, and separation by centrifugation (3000 rpm for 5 min). The particle number recoveries of spiked Ag and Au NPs were 88 ± 0.9% and 95 ± 1.1%, respectively, while Ti-containing NPs had a particle number concentration of 8.2 × 10⁶ particles/mg and an average size of 70 nm in tested mussels. Furthermore, titanium oxide NPs, including rutile, anatase, and Magnéli phases (Ti_xO_2x-1) were found ubiquitously in 10 shellfish based on the optimal method. The particle number concentrations and average sizes of the Ti-containing NPs were 2.1 × 10⁶-8.4 × 10⁶ particles/mg and 70-80 nm, respectively. These Ti-containing NPs, such as TiO₂, accounted for about half of the Ti mass in shellfish, indicating that marine shellfish may be a significant sink for Ti-containing NPs.

Zinc oxide nanoparticles: potential effects on soil properties, crop production, food processing, and food quality

The use of zinc oxide nanoparticles (ZnO NPs) is expected to increase soil fertility, crop productivity, and food quality. However, the potential effects of ZnO NP utilization should be deeply understood. This review highlights the behavior of ZnO NPs in soil and their interactions with the soil components. The review discusses the potential effects of ZnO NPs on plants and their mechanisms of action on plants and how these mechanisms are related to their physicochemical properties. The impact of current applications of ZnO NPs in the food industry is also discussed. Based on the literature reviewed, soil properties play a vital role in dispersing, aggregation, stability, bioavailability, and transport of ZnO NPs and their release into the soil. The transfer of ZnO NPs into the soil can affect the soil components, and subsequently, the structure of plants. The toxic effects of ZnO NPs on plants and microbes are caused by various mechanisms, mainly through the generation of reactive oxygen species, lysosomal destabilization, DNA damage, and the reduction of oxidative stress through direct penetration/liberation of Zn2+ ions in plant/microbe cells. The integration of ZnO NPs in food processing improves the properties of the relative ZnO NP-based nano-sensing, active packing, and food/feed bioactive ingredients delivery systems, leading to better food quality and safety. The unregulated/unsafe discharge concentrations of ZnO NPs into the soil, edible plant tissues, and processed foods raise environmental/safety concerns and adverse effects. Therefore, the safety issues related to ZnO NP applications in the soil, plants, and food are also discussed.

Zn concentration decline and apical endpoints recovery of earthworms (E. andrei) after removal from an acidic soil spiked with coated ZnO nanoparticles

ZnO nanoparticles (ZnO-NPs) can reach soil in both deliberate and non-deliberate ways, which leads to contamination. Notwithstanding knowledge about ZnO-NPs impacts on earthworms inhabiting these soils is limited and gaps appear in the recovery of damaged functions after their migration to unpolluted environments. To estimate these impacts, earthworms (Eisenia andrei) were exposed to different concentrations of coated ZnO-NPs (20, 250, 500, 1000 mgZnkg^-1) in an acidic agricultural soil (pH 5.4) for 28 days. Subsequently, earthworms were placed in the same unpolluted soil to study the depletion of Zn accumulated and the recovery potential of the affected functions for another 28-day period.In the exposure phase, ecotoxicological responses were dose-dependent. Mortality and growth were affected at 500 and 1000 mg kg^- 1, and the reproduction was impaired from 250 mgZnkg^- 1 compared to control (54% fecundity and 80% fertility reduction). Zn uptake increased with coated ZnO-NPs in soil but it did not exceed 163 mgZnkg^- 1 earthworm. During the recovery period, the Zn in earthworms were similar to the control regardless of the initially Zn accumulated. Reproduction parameters returned to the control values in the animals pre-exposed to 250 mgZnkg^- 1 as coated ZnO-NP. In the earthworms preexposed to the two highest doses, growth and fertility were stimulated compared to the control when placed in clean soil, but not fecundity. However, the total hatchlings number did not reach the control figures after 28 days, but probably would for in longer times, which would be key for maintaining earthworm populations.

Insights into the mechanisms underlying the remediation potential of earthworms in contaminated soil: A critical review of research progress and prospects

In recent years, soil pollution is a major global concern drawing worldwide attention. Earthworms can resist high concentrations of soil pollutants and play a vital role in removing them effectively. Vermiremediation, using earthworms to remove contaminants from soil or help to degrade non-recyclable chemicals, is proved to be an alternative, low-cost technology for treating contaminated soil. However, knowledge about the mechanisms and framework of the vermiremediation various organic and inorganic contaminants is still limited. Therefore, we reviewed the research progress of effects of soil contaminants on earthworms and potential of earthworm used for remediation soil contaminated with heavy metals, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), pesticides, as well as crude oil. Especially, the possible processes, mechanisms, advantages and limitations, and how to boost the efficiency of vermiremediation are well addressed in this review. Finally, future prospects of vermiremediation soil contamination are listed to promote further studies and application of vermiremediation in contaminated soils.

A Comparative Study of Zinc Oxide Nanotoxicity on Reproductive Potential of an Earthworm in Natural and Artificial Substrates

The toxic impacts of zinc oxide nanoparticles (ZnO NPs) on reproductive potential of the earthworm, Eisenia fetida were studied in relation to varying temperature and pH in natural (NS) and artificial substrate (AS). The ZnO NPs decreased cocoon production, hatching and rate of reproduction as a function of increasing concentration, temperature and exposure period. The gradation of temperature and pH to get a better reproductive potential was found to be [Formula: see text]C and [Formula: see text], respectively. Cocoon production was higher in NS than the AS. It may be due to sufficient food availability in NS. Survival of adult worms was decreased with increase in ZnO NPs and exposure period. The rate of reproduction was significantly higher in NS as compared to AS at [Formula: see text]C. The present findings suggested that ZnO NPs retard the reproductive potential of E. fetida and may also be hazardous to pedoecosystem and fauna living there in. Temperature of [Formula: see text]C, pH 6.5 and NS as vermibed were the most suitable conditions to maintain worthy rate of reproduction and reduce ZnO NPs toxicity.

CuO Nanoparticles Alter the Rhizospheric Bacterial Community and Local Nitrogen Cycling for Wheat Grown in a Calcareous Soil

The application of nanoparticles (NPs) to soils, as either fertilizers or fungicides (e.g., CuO NPs), has been proposed to improve the sustainability of agriculture. The observed effects could result directly from the NP-plant interactions or indirectly through effects on the soil microbiome. The objective of this study was to assess the effects of CuO NPs on the changes in the bacterial community structure and nitrogen-cycling-associated functions in a high pH soil and to correlate these changes with nitrate accumulation, soil parameter changes, and plant growth over 28 days. Triticum aestivum seedlings were exposed to 50 mg/kg CuO NPs, 50 mg/kg CuSO₄, or 0.5 mg/kg CuSO₄ in a standard soil (Lufa 2.1 soil, pH adjusted to 7.6). While Cu treatments reduced nitrate accumulation in the bulk soil, the effects were opposite in the rhizosphere (the soil influenced by root exudates). While nitrate accumulation in bulk soil negatively correlated with total Cu concentration, part of the nitrate concentration in the rhizosphere was explained by root uptake during plant growth, the rest being modulated by Cu treatments. The abundance of genes involved in the nitrogen cycle in the rhizosphere soil correlated with the ionic copper concentration. The increased nitrate concentration in the rhizosphere correlated with an increase of the gene abundance related to the nitrogen fixation and a decrease of denitrification gene abundance. Microbial diversity in bulk or rhizosphere soil under the different treatments alone could not explain these variations, while differences in the assemblages of bacteria associated with these functional gene abundances gave good insights. This study highlights the complexity of microbial N-related function in the rhizosphere and the need to characterize the rhizosphere soil, plant growth and root activity, NP (bio)transformations, along with microbial networks, to understand the impact of agrochemicals (here CuO NPs) on soil fertility.

Quantitative prediction of mixture toxicity of AgNO3 and ZnO nanoparticles on Daphnia magna

Once metal-based engineered nanoparticles (NPs) are released into the aquatic environment, they are expected to interact with other existing co-contaminants. A knowledge gap exists as to how the interaction of NPs with other co-contaminants occurs. Here we selected ZnO NPs among various NPs, with Ag ion existing as a contaminant in the aquatic environment by Ag NPs widely used. A novel modeling strategy was demonstrated enabling quantitative and predictive evaluation of the aqueous mixture nanotoxicity. Individual and binary mixture toxicity tests of ZnO NPs and silver (as AgNO3) on Daphnia magna were conducted and compared to determine whether the presence of Ag ions affects the toxicity of ZnO NPs. Binary mixture toxicity was evaluated based on the concentration addition (CA) and independent action models. The CA dose-ratio dependent model was found to be the model of best fit for describing the pattern of mixture toxicity. The MIX I and MIX III suspensions (higher ratios of ZnO NPs to AgNO3) showed a synergism, whereas the MIX II suspension (lower ratio of ZnO NPs to AgNO3) showed an antagonism. The synergistic mixture toxicity at higher ratios of ZnO NPs to AgNO3 was caused by either the physiological or metabolic disturbance induced by the excessive ionic Zn or increased transport and accumulation in D. magna via the formation of complex of ionic Ag with ZnO NPs. Therefore, the toxicity level contributed via their aggregation and physicochemical properties and the dissolved ions played a crucial role in the mixture toxicities of the NPs.

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.

Effect of ageing of bare and coated nanoparticles of zinc oxide applied to soil on the Zn behaviour and toxicity to fish cells due to transfer from soil to water bodies

This study evaluated the influence of ageing of ZnO nanoparticles (NPs) applied to soil on the potential availability and chemical speciation of Zn, and also of their toxicity to aquatic organisms due to transfer of contaminants from soil to water. To this end, soil samples were spiked with two types of bare nanoparticles: b1ZnO NPs (rod- and elongated-shaped) and b2ZnO NPs (near-spherical shaped) and ZnO NPs coated with (3-aminopropyl)triethoxysilane (cZnO NPs) within the 0-800 mg Zn kg^-1 soil dose range, and were left to age for 0, 30, 60 and 90 days. The available concentration and speciation of Zn in soil were determined by the DGT (diffusive gradients in thin films) technique and sequential extraction procedures, respectively. The toxicity of the aqueous extracts from the ZnO NP-treated soils was assessed in vitro in established fish cell lines (RTG-2). The highest distribution percentages of the applied Zn occurred in the organically complexed (OC), followed by the exchangeable (EXC) fraction, for all NP types, applied doses and incubation times. The toxicity of NPs depended on their intrinsic properties: b1ZnO NPs affected the membrane function, reductase enzyme activity and, to a lesser extent, reactive oxygen species (ROS) levels of fish cells, whereas b2ZnO NPs and cZnO NPs affected mainly ROS generation. Ageing increased Zn soil availability, but toxicity to fish cells showed no trend over time. The particle dissolution of ZnO NPs did not explain the observed toxicity, hence a nanoparticles-specific effect should be assumed. The findings of this study seem to indicate that the transfer of ZnO NP from contaminated soils to aquatic ecosystems should be addressed.

Study of Zn availability, uptake, and effects on earthworms of zinc oxide nanoparticle versus bulk applied to two agricultural soils: Acidic and calcareous

The increasing use of zinc oxide nanoparticles (ZnO NPs) in agriculture renders it necessary to evaluate their impact on soil non-target organisms. This work studies Zn availability to earthworms from the ZnO (NP and bulk) applied to two agricultural soils with a different pH at 20, 225, 500, and 1000 mg Zn kg^-1. Zn uptakes and the effects on Eisenia andrei, grown under controlled conditions, were determined. Effects were assessed at three levels: organisms, mortality, growth and reproduction; biochemical, catalase and glutathione S-transferase activities, malondialdehyde (MDA), and protein content; cellular in coelomocytes, reactive oxygen species (ROS) generation, lysosomal membrane alterations (RN) and mitochondrial dysfunction (MTT). Available Zn was 100-fold higher in acidic than in calcareous soil and did not differ among ZnO (NP or bulk). Zn in worms was auto-regulated regardless of the soil Zn concentration, pH and ZnO size. Effects on mortality and weight were observed only in the acidic soil at the highest concentration, ZnO NPs reduced survival and body weight, while ZnO bulk reduced body weight. Reproduction parameters in acidic soil were: EC50 (fecundity) 277 and 256 mg Zn kg-1 and EC50 (fertility) 177 and 179 mg Zn kg-1 for ZnO NPs and bulk, respectively, with no found NP-specific effects. No responses of enzymatic activities, MDA and MTT were detected. ROS and RN were altered in the coelomocyte cells of earthworms in the two soils, but effects depended on ZnO size suggesting nanospecific effects. Soil pH governs toxicity more than ZnO size regardless of body Zn concentration.

Joint effects of zinc oxide nanoparticles and chlorpyrifos on the reproduction and cellular stress responses of the earthworm Eisenia andrei

The co-exposure of soil organisms to ZnO nanoparticles (ZnO NPs) and pesticides is likely to take place in agricultural soils. However, the impacts of co-exposure on terrestrial ecosystems are virtually unknown. In this paper, Eisenia andrei was exposed for a 28-day period to serial concentrations of ZnO NPs and/or the organophosphate insecticide chlorpyrifos (CPF) in natural soil, and was evaluated for single and joint effects. Zn and CPF accumulation in earthworm tissue was also determined. In the single assay, ZnO NPs and CPF caused statistical significant effects on survival and growth, but mainly on reproduction. Significant reductions in fecundity and fertility were detected with EC50 values of 278 and 179 mg Zn/kg for ZnO NPs, and of 50.75 and 38.24 mg/kg for CPF, respectively. The most notable effect on biomarkers was the reduction in acetylcholinesterase (AChE) activity caused by CPF, which reflected the neurotoxicity of this compound. The results of the combined assay indicated that co-exposure to ZnO NPs and CPF increased adverse effects in E. andrei. According to the independent action model, the binary mixtures showed a synergism (a stronger effect than expected from single exposures) on earthworm reproduction, which became up to 84% higher than the theoretically predicted values. Zn, and especially CPF accumulation, were influenced by the co-exposure. These results underpin the need to consider the effects of mixtures of NPs and organic chemicals on soil to adequately make ecological risk assessments of NPs.

Combined effects of ZnO nanoparticles and toxic Microcystis on life-history traits of Daphnia magna

Rise in cyanobacterial blooms and massive discharge of nanoparticles (NPs) in aquatic ecosystems cause zooplankton to be exposed in toxic food and NPs simultaneously, which may impact on zooplankton interactively. Therefore, the present study focused on assessing the combined effects of different ZnO NPs levels (0, 0.10, 0.15, 0.20 mg L^-1) and different proportions of toxic Microcystis (0%, 10%, 20%, 30%) in the food on a model zooplankton, Daphnia magna. The results showed that both toxic Microcystis and ZnO NPs significantly delayed the development of D. magna to maturation, but there was no significant interaction between the two factors on the times to maturation except the body length at maturation. Both ZnO NPs and toxic Microcystis also significantly decreased the number of neonates in the first brood, total offspring, and number of broods per female, and there was a significant interaction between ZnO NPs and food composition on the reproductive performance of D. magna. Specifically, presence of toxic Microcystis reduced the gap among the effects of different ZnO NPs concentrations on the reproductive performance of D. magna. When the ZnO NPs concentration was at 0.15 mg L^-1, the gap of the reproductive performance among different proportions of toxic Microcystis also tended to be narrow. Similar phenomenon also occurred in mortality. Such results suggested that low concentration of ZnO NPs and toxic Microcystis can mutually attenuate their harmful effects on D. magna, which has significantly implications in appropriately assessing the ecotoxicological effects of emerging pollutants in a complex food conditions.

Energy reserves and respiration rate in the earthworm Eisenia andrei after exposure to zinc in nanoparticle or ionic form

The energy budget is an indicator of an organism's overall condition. Changes in energy reserves and/or energy consumption have been used as biomarkers of toxic stress. To understand the effects of different forms and concentrations of Zn and the costs of effective Zn regulation by the earthworm Eisenia andrei, we performed a toxicokinetic experiment in which individuals were sampled over time to determine the available energy reserves (total carbohydrate, protein, and lipid content), energy consumption (measured at the cellular level and as the whole-animal respiration rate), and internal Zn concentration. The earthworms were exposed to ZnCl2 or zinc nanoparticles (ZnO-NPs) in Lufa 2.2 soil for 21 days (contamination phase), followed by 14 days of elimination in clean soil (decontamination phase). Carbohydrates were the only energy reserves with significantly lower levels following ZnO-NP 1000 treatment than following other treatments (p ≤ 0.00001) in the contamination phase. The total available energy reserves and protein content did not differ among treatments, but a significant effect of exposure time was observed (p ≤ 0.0001). Exposure to Zn (both ions and NPs) increased energy consumption at the cellular level, reflecting the high energy demand of the stress response. The results indicated that E. andrei can regulate internal Zn concentrations efficiently, regardless of form or concentration, without considerable impact on energy reserves or respiration rate.

Comparative study of the phytotoxicity of ZnO nanoparticles and Zn accumulation in nine crops grown in a calcareous soil and an acidic soil

The increasing use of zinc oxide nanoparticles (ZnO NPs) in agriculture and consumer products has created the need to evaluate their impact on crops. Nine crops were investigated: wheat, maize, radish, bean, lettuce, tomato, pea, cucumber, and beet. The toxic effects of ZnO NPs on seed germination, plant growth, and biochemical parameters, including photosynthetic pigments, protein and malondialdehyde (MDA) content, reactive oxygen species (ROS), enzymes of the antioxidant defence system, as well as the Zn translocation in the plants were investigated using pots containing non-contaminated or ZnO NP-contaminated soil at concentrations of 20, 225, 450, and 900 mg Zn kg^-1. Two soils with different physicochemical properties, namely a calcareous soil and an acidic soil, were used. The total and available Zn in the soils were correlated with the Zn in the plants (roots and shoots) and the observed effects. In the calcareous soil, the available Zn was very low and the phytotoxicity was limited to a slight reduction in the biomass for wheat, cucumber, and beet at the highest concentration. Only beet showed an increase in photosynthetic pigments. The parameters related to oxidative stress were affected to different degrees depending on the crop, with the exceptions of maize, lettuce, pea, and beet. In the acidic soil, the available Zn was high, and the germination of bean, tomato, lettuce, and beet, and the growth of most of the crops were seriously affected. The calculated EC50 values (growth) in the acidic soil ranged from 110 to 520 mg Zn kg^-1. The photosynthetic pigments and most of the markers of oxidative stress were negatively affected in maize, wheat, bean, and pea. However, these changes were not always associated with a decrease in plant weight. In summary, soil pH and plant species are key factors affecting the Zn availability and phytotoxicity of ZnO NPs.

Study of zinc oxide nanoparticles and zinc chloride toxicity to annelid Enchytraeus crypticus in modified agar-based media

Acute toxicity of zinc oxide nanoparticle (ZnO-NP, mean particle size diameter of 10 nm) powder and water-soluble salt of zinc (ZnCl₂) to annelid Enchytraeus crypticus was tested using an agar-based nutrient-enriched medium with the addition of kaolin and humic acids (HA). Adults of the E. crypticus were cultivated in pure agar and in three types of modified exposure media containing different proportions of model soil constituents. Potworms were exposed to zinc in both forms (1-1000 mg kg^-1 of agar) for 96 h. In experiments with ZnCl₂, toxicity of zinc was the highest in pure agar followed by agar with HA and agar with kaolin and HA and the lowest toxicity was observed in agar with kaolin. The corresponding LC₅₀ values were 13.2, 28.8, 39.4, and 75.4 mg kg^-1 respectively. In contrast, zinc in the form of ZnO-NPs was most toxic in the presence of HA followed by pure agar, agar with kaolin, and kaolin with HA. In this case, LC₅₀ values were 15.8, 43.5, 111, and 122 mg kg^-1 respectively. Scanning electron microscopy revealed that the smallest agglomerates occurred in the presence of kaolin, where ZnO-NPs were sealed in a kaolin shell. This effect reduced the bioavailability and toxicity of the NPs. In contrast, larger agglomerates were observed in the presence of HA but a larger amount of zinc was dispersed in the volume of agar.

Testing ZnO nanoparticle ecotoxicity: linking time variable exposure to effects on different marine model organisms

Zinc oxide nanoparticles (ZnO NPs) are increasingly used in several personal care products, with high potential to be released directly into marine environment with consequent adverse impact on marine biota. This paper aimed to compare the ecotoxicological effect of ZnO NPs (< 100 nm) towards three marine organisms widely used in toxicity assessment: an algal species (Dunaliella tertiolecta), a bioluminescent bacterium (Vibrio fischeri), and a crustacean (Artemia salina). Bulk ZnO (ZnO bulk, 200 nm) and ionic zinc were also investigated for understanding the role of size and of ionic release in the ZnO toxic action. To this aim, different ecotoxicological tests were used: the inhibition of bioluminescence with V. fischeri at three exposure times (5, 15, and 30 min); the D. tertiolecta growth inhibition at 24, 48, and 72 h; the A. salina mortality at 24-96 h, and A. salina mortality and body growth each 3 days along chronic exposure (14 days). For all selected species, ZnO NPs toxicity was strictly dependent on the exposure time and different sensitivities were recorded: ZnO NPs were more toxic towards algae (EC₅₀ 2.2 mg Zn/L) but relatively less toxic towards bacteria (EC₅₀ 17 mg Zn/L) and crustaceans (EC₅₀ 96 h 58 mg Zn/L). During the 14-day chronic exposure of A. salina, ZnO NPs had a significant inhibition of vitality and body length (EC₅₀14d 0.02 mg Zn/L), while the effect of ZnSO₄ was not statistically different from the control. ZnO NP toxicity was related to zinc ions and to interactions of particle/aggregates with target organisms and therefore to NP behavior in the testing matrix and to the different testing time exposures.

Differential Contribution of Constituent Metal Ions to the Cytotoxic Effects of Fast-Dissolving Metal-Oxide Nanoparticles

The main mechanism of toxicity for fast-dissolving nanoparticles (NPs) is relatively simple as it originates from the intrinsic toxicity of their constituent elements rather than complicated surface reactivity. However, there is little information about the compared toxicity of fast-dissolving NP and its constituent ion, which is essential for understanding the mechanism of NP toxicity and the development of a structure-toxicity relationship (STR) model. Herein, we selected three types of fast-dissolving metal-oxide NPs (CoO, CuO, and ZnO) and constituent metal chlorides (CoCl₂, CuCl₂, and ZnCl₂) to compare dose-response curves between NP and its constituent metal. These materials were treated relevant cell lines for inhalation setting (i.e., differentiated THP-1 cells for macrophages and A549 cells for alveolar epithelial cells) and cytotoxicity as an endpoint was evaluated at 24 h post-incubation. The results showed that CoO and CuO NPs in both cell types showed similar patterns of dose-response curves and cytotoxic potential compared to that of their respective metal chloride. On the other hand, ZnO NPs in both cell types showed a completely different dose-response curve compared to that of ZnCl₂: ZnO NPs showed modest slope and much less potential for cytotoxicity compared to that of ZnCl₂. These results imply that fast-dissolving metal-oxide NPs are not always have similar dose-response curves and toxic potentials compared to their constituent metal chlorides and this may be due to the differential mechanism of intracellular uptake of these substances and their interaction with intracellular detoxification molecules. Further investigations are needed for the use of toxic potential of metal ions as a predicting factors of fast-dissolving NPs toxicity. In addition, chelating agent specific for dissolved metal ions can be applied for the treatment of these fast-dissolving NPs.

Pterodon emarginatus oleoresin-based nanoemulsion as a promising tool for Culex quinquefasciatus (Diptera: Culicidae) control

BACKGROUND

Preparation of nanoformulations using natural products as bioactive substances is considered very promising for innovative larvicidal agents. On this context, oil in water nanoemulsions develop a main role, since they satisfactorily disperse poor-water soluble substances, such as herbal oils, in aqueous media. Pterodon emarginatus, popularly known as sucupira, has a promising bioactive oleoresin. However, to our knowledge, no previous studies were carried out to evaluate its potential against Culex quinquefasciatus, the main vector of the tropical neglected disease called lymphatic filariasis or elephantiasis. Thus, we aimed to investigate influence of different pairs of surfactants in nanoemulsion formation and investigate if a sucupira oleoresin-based nanoemulsion has promising larvicidal activity against this C. quinquefasciatus. We also evaluated morphological alteration, possible mechanism of insecticidal action and ecotoxicity of the nanoemulsion against a non-target organism.

RESULTS

Among the different pairs of surfactants that were tested, nanoemulsions obtained with polysorbate 80/sorbitan monooleate and polysorbate 80/sorbitan trioleate presented smallest mean droplet size just afterwards preparation, respectively 151.0 ± 2.252 and 160.7 ± 1.493 nm. They presented high negative zeta potential values, low polydispersity index (<0.300) and did not present great alteration in mean droplet size and polydispersity index after 1 day of preparation. Overall, nanoemulsion prepared with polysorbate 80/sorbitan monooleate was considered more stable and was chosen for biological assays. It presented low LC50 value against larvae (34.75; 7.31-51.86 mg/L) after 48 h of treatment and some morphological alteration was observed. The nanoemulsion did not inhibit acetylcholinesterase of C. quinquefasciatus larvae. It was not toxic to green algae Chlorella vulgaris at low concentration (25 mg/L).

CONCLUSIONS

Our results suggest that optimal nanoemulsions may be prepared with different surfactants using a low cost and low energy simple method. Moreover, this prototype proved to be effective against C. quinquefasciatus, being considered an ecofriendly novel nanoproduct that can be useful in integrated control programs of vector control.

Oxidative Stress, Cytotoxicity and Genotoxicity in Earthworm Eisenia fetida at Different Di-n-Butyl Phthalate Exposure Levels

Recognized as ubiquitous contaminants in soil, the environmental risk of phthalic acid esters (PAEs) is of great concern recently. Effects of di-n-butyl phthalate (DnBP), an extensively used PAE compound to Eisenia fetida have been investigated in spiked natural brown yellow soil (Alfisol) for soil contact test. The toxicity of DnBP to E. fetida on the activity of superoxide dismutase (SOD) activity, peroxidase (POD), reactive oxygen species (ROS) content, and the apoptosis of coelomocytes and DNA damage at the 7th, 14th, 21st and 28th day of the incubation have been paid close attention to. In general, SOD activity and ROS content were significantly induced, opposite to total protein content and POD activity, during the toxicity test of 28 days especially under concentrations higher than 2.5 mg kg-1. The reduction in neutral red retention (NRR) time along with the increase of dead coelomocytes as the increasing of DnBP concentrations, indicating severe damage to cell viability under varying pollutant stress during cultivation, which could also be proved by comet assay results for exerting evident DNA damage in coelomocytes. DnBP in spiked natural soil could indeed cause damage to tissues, coelomocytes and the nucleus of E. fetida. The key point of the apparent change in different indices presented around 2.5 mg DnBP kg-1 soil, which could be recommended as the threshold of DnBP soil contamination, so that further investigation on threshold values to other soil animals or microorganisms could be discussed.