Observed Effect Concentration Research Articles

Toxicodynamics of cadmium in the green mussel Perna viridis (Linnaeus, 1758) using bioenergetic and physiological biomarkers.

This study evaluated the toxicity of cadmium (Cd) on the green mussel Perna viridis, aiming to identify toxicological endpoints and investigate its responses across physiological, bioenergetic, and biochemical parameters. The 96-hour LC50 value for Cd in P. viridis was 3.03 ± 0.12 mg L-1, with a 95% confidence interval of 2.35-3.91 mg L-1. Chronic toxicity tests revealed a No Observable Effect Concentration (NOEC), Lowest Observable Effect Concentration (LOEC), and chronic toxicity values of 0.20, 0.37, and 0.29 mg L-1, respectively. Cadmium accumulation in treated mussels increased 46- to 215-fold compared to the control group. Superoxide dismutase, catalase, glutathione S-transferase, and glutathione peroxidase levels in exposed mussels exhibited a significant increase compared to the control group. The redox index ratio, acetylcholinesterase activity, and lysosomal membrane stability decreased with increasing exposure concentrations. Levels of reduced and oxidized glutathione, glutathione reductase, lipid peroxidation, and metallothionein-like proteins increased in exposed mussels. Clearance rate, respiration rate, and excretion rate decreased in a dose-dependent manner. Protein, carbohydrate, and lipid levels decreased with increasing exposure concentration (p < 0.001). Mitochondrial electron transport system activity increased, while cellular energy allocation (p < 0.001) and scope for growth decreased in a dose-dependent manner (p < 0.01). The significant increase in antioxidants suggests heightened oxidative stress in mussels under Cd exposure. The physiological activities of the mussels were severely affected, ultimately leading to a reduced scope for growth. The toxicological data generated in this study contribute to the development of seawater quality criteria for the metal Cd.

Paralysis caused by dinotefuran at environmental concentration via interfering the Ca2+–ROS–mitochondria pathway in Chironomus kiiensis

IntroductionDinotefuran as the third-generation of neonicotinoid insecticides is extensively used in agriculture worldwide, posing a potential toxic threat to non-target animals and humans. However, the chronic toxicity mechanism related to mitochondria damage of dinotefuran to non-target animals at environmental concentration is unclear.MethodsIn this study, the mitochondria damage and oxidative stress of dinotefuran on Chironomus kiiensis were investigated at environmental concentrations by long-term exposure. At the same time, relevant gene expressions of these toxicity indexes were measured as sensitive ecotoxicity biomarkers to reflect the toxic effects of dinotefuran on Chironomidae.ResultsOur present study showed that chronic exposure to environmental concentrations of dinotefuran resulted in behavioral inhibition in the larvae of Chironomidae. For burrowing inhibition of 10 days, the lowest observed-effect concentration (LOEC) and 50% inhibitory concentration (IC50) were 0.01 (0.01–0.04) and 0.60 (0.44–0.82) μg/L, respectively. Dinotefuran promoted the release of intracellular calcium ions (Ca2+) in Chironomidae via dysregulating the gene expressions of atp2b, camk ii, and calm. Subsequently, the disruption of the Ca2+ signaling pathway induced oxidative stress by raising reactive oxygen species (ROS), hydrogen peroxide (H2O2), and malonaldehyde (MDA) levels. Thus, the over-release of Ca2+ and ROS disordered the normal functioning of mitochondrial-related pathways by dysregulating the expressions of mitochondria-related genes of atpef0a, sdha, and cyt b.ConclusionOur findings showed that low environmental concentrations of dinotefuran caused paralysis of the midge via interfering the Ca2+–ROS–mitochondria pathway. These results provided data support for assessing the potential environmental risk of dinotefuran.

Effects of anthranilic diamide insecticides on metamorphosis in the common toad Rhinella arenarum (Hensel, 1867) at concentrations found in aquatic environments

ABSTRACT Anthranilic diamides (AD) are a modern class of insecticides used as alternatives to pyrethroids and neonicotinoids, particularly against lepidopteran pests. Despite their widespread use and presence in surface waters, little is known regarding their effects on amphibians. The aim of this study was to examine the effects of environmentally-relevant concentrations of AD insecticides chlorantraniliprole (CHLO) and cyantraniliprole (CYAN) on metamorphosis of the toad Rhinella arenarum. Tadpoles were exposed to CHLO or CYAN at concentrations ranging from 5 and 5000 µg/L from stage 27 until metamorphosis completion. Both insecticides produced a non-monotonic acceleration of the time required for individuals to progress through development and a decrease in the proportion of individuals completing metamorphosis, although a delay in metamorphosis was also observed at 5 µg/L of CHLO. Snout-vent length and body weight of metamorphosed toads were not markedly affected by either insecticide. CHLO was more toxic than CYAN, with a lowest observed effect concentration (LOEC) for CHLO on time to metamorphosis defined as 5 µg/L compared to 5000 µg/L for CYAN. The LOEC for reduced metamorphic success defined as 50 µg/L for CHLO compared to 500 µg/L for CYAN. As most effects occurred after stage 39, when metamorphosis depends upon thyroid hormones, it is conceivable that that AD insecticides act as endocrine disruptors. These findings suggest that contamination of surface waters with CHLO and CYAN may disrupt amphibian development in the wild and warrant further research to investigate the possibility of endocrine-disruption by ADs.

Cytotoxicity and mechanisms of perfluorobutane sulfonate (PFBS) in umbilical cord fibroblast cells of Yangtze finless porpoise

Yangtze finless porpoises (YFP) accumulate high levels of per- and polyfluoroalkyl substances (PFASs). However, the health impacts of PFASs to YFP are still unknown because it is technically and ethically unfeasible to use the critically endangered YFP in toxicological exposures. To uncover the potential toxicities of PFASs to YFP, this study exposed a YFP umbilical cord fibroblast cell line to perfluorobutane sulfonate (PFBS), an emerging PFASs pollutant in the aquatic environments. After exposure, the cytotoxicity and mechanisms of PFBS were explored. Our preliminary experiments found that PFBS compromised the cell viability in a concentration and duration dependent manner. In an exposure of 48-h duration, the maximum no observed effect concentration (NOEC) of PFBS was determined to be 400 µM. High-throughput proteomics were then conducted to identify the differentially expressed proteins in YFP cells exposed to 400 µM PFBS for 48 h. The results found that PFBS exposure significantly perturbed the proteome fingerprints of YFP umbilical cord fibroblast cells. Functional annotation of differential proteins showed that PFBS had the potential to impair a variety of biological processes associated with the immunity, oxidative stress, metabolism, and proteolysis. Consistently, the intracellular levels of reactive oxygen species (ROS) and proinflammatory cytokine IL-1β were significantly increased by PFBS in YFP umbilical cord fibroblast cells. Overall, this study highlights the toxic effects of emerging PFASs on YFP and provides reference data to evaluate the health risks of aquatic pollution under the context of national YFP protection. To our knowledge, this is the first omics study using YFP umbilical cord fibroblast cells in ecotoxicology of PFASs, which is applicable to various cetacean species and pollutants.

The Effects of Co-Exposure to Antifoulants and Microplastics on the Survival, Oxidative Status, and Cholinergic System of a Marine Mysid.

Antifoulants such as copper pyrithione (CuPT) and zinc pyrithione (ZnPT) are widespread and hazardous pollutants in aquatic environments. The presence of microplastics (MPs) introduces significant uncertainty regarding the toxicity of CuPT and ZnPT, as their effects can be influenced by MPs. There is a limited understanding of the toxic potential of CuPT and ZnPT when they coexist with MPs. Here, the marine mysid Neomysis awatchensis was treated using no observed effect concentration (NOEC) values of CuPT and ZnPT premixed with MPs (1 µm; 1-100 particles mL-1). The presence of MPs increased the toxicity of the antifoulants in juvenile and adult mysids over 96 h. The additive effect of the MPs varied by chemical; feeding was only reduced by CuPT with MPs, whereas no fluctuation in feeding was observed in response to ZnPT with MPs. Co-exposure to antifoulants and MPs increased malonaldehyde levels, but the response of antioxidant components varied by chemical. In mysids co-exposed to CuPT and MPs, the activity levels of catalase and superoxide dismutase were decreased, whereas their enzymatic activity levels were elevated by co-exposure to ZnPT and MPs. Similarly, depletion of glutathione (GSH) was observed in mysids co-exposed to CuPT and MPs, with significant reductions in GSH reductase (GR) and peroxidase (GPx). However, the GSH level was increased by co-exposure to ZnPT and MPs, with elevations in GR and GPx activity levels. Significant inhibition of acetylcholinesterase activity was only observed in response to CuPT and MPs. These results suggest that MPs can increase toxicity via additive and/or synergistic effects through oxidative imbalance, but these effects of MPs can vary with different chemicals.

Systematization of a toxicity screening method based on a combination of chemical analysis and the delayed fluorescence algal growth inhibition test for use in emergency environmental surveys.

In recent years, heavy rainfall disasters linked to climate change have become more frequent, raising concerns about the release of chemicals stored in factories. Assessing chemical contamination during such emergencies therefore necessitates the development of a quick and easy method for evaluating hazardous contaminants in combination with toxicity testing. This study proposes a "toxicity screening" method that combines biological response testing and chemical analysis to systematically evaluate hazardous contaminants in emergency situations. The toxicity screening method evaluates the water quality in three steps, including water quality measurements and a delayed fluorescence (DF) assay, metal content measurements and a DF assay, and targeted screening analysis and a DF assay. The efficacy of this method was tested using industrial wastewater from 14 locations. Seven of the samples were non-toxic, while the other seven samples were toxic, displaying no observed effect concentration (NOEC) values ranging from 0.625 to 20%. Two toxic samples in the first phase possessed high total chlorine concentrations (0.4mg L-1) and conductivities (2200 mS m-1), indicating that the main sources of toxicity were residual chlorine and a high salt concentration. In the second phase, metal content analysis identified metals as the toxicity cause in four samples. In the third phase, the organic contaminants were analyzed, and tri-n-octyl phosphate (TNOP) was detected at a concentration of 0.00027mg L-1. The results of solid-phase extraction experiments and exposure tests with TNOP alone indicated that the contribution of TNOP to the toxicity was negligible and that chemicals not adsorbed on the solid-phase extraction cartridges were the cause of toxicity. The proposed method can therefore be considered effective for disaster-related water quality assessment, delivering results within 12days.

Transcriptomic Point of Departure (tPOD) of androstenedione in zebrafish embryos as a potential surrogate for chronic endpoints

The transcriptomic Point of Departure (tPOD) is increasingly used in ecotoxicology to derive quantitative endpoints from RNA sequencing studies. Utilizing transcriptomic data in zebrafish embryos as a New Approach Methodology (NAM) is beneficial due to its acknowledgment as an alternative to animal testing under EU Directive 2010/63/EU. Transcriptomic profiles are available in zebrafish for various modes of action (MoA). The limited literature available suggest that tPOD values from Fish Embryo Toxicity (FET) tests align with, but are generally lower than, No Observed Effect Concentrations (NOEC) from long-term chronic fish toxicity tests.In studies with the androgenic hormone androstenedione in a Fish Sexual Development Test (FSDT), a significant shift in the sex ratio towards males was noted at all test concentrations, making it impossible to determine a NOEC (NOEC <4.34 μg/L). To avoid additional animal testing in a repetition of the FSDT and adhere to the 3Rs principle (replacement, reduction, and refinement), a modified zebrafish FET (zFET) was conducted aiming to determine a regulatory acceptable effect threshold. This involved lower concentration ranges (20 to 6105 ng/L), overlapping with the masculinization-observed concentrations in the FSDT. The tPOD analysis in zFET showed consistent results with previous FSDT findings, observing strong expression changes in androgen-dependent genes at higher concentrations but not at lower ones, demonstrating a concentration-response relationship.The tPOD values for androstenedione were determined as 24 ng/L (10th percentile), 60 ng/L (20th gene), and 69 ng/L (1st peak). The 10th percentile tPOD value in zFET was 200 times lower than the lowest concentration in the FSDT. Comparing the tPOD values to literature suggests their potential to inform on the NOEC range in FSDT tests.

Assessing ecological responses of exposure to the pyrethroid insecticide lambda-cyhalothrin in sub-tropical freshwater ecosystems

Pyrethroid insecticides are widely detected in aquatic ecosystems due to their extensive use in agriculture and horticulture, which could pose a potential risk to aquatic non-target organisms. While previous ecotoxicological studies have been conducted mainly with standard tests and local species under temperate conditions, scarce information is available on the effects of pyrethroid insecticides on communities and ecosystems under (sub-)tropical conditions. A single application of lambda-cyhalothrin at concentrations of 0, 9, 30, and 100 ng/L was evaluated in outdoor mesocosms under sub-tropical conditions. Lambda-cyhalothrin was found to dissipate rapidly in the water column, with only 11 % and 7 % of the remaining dose measured at 1 and 3 days after application, respectively. Lambda-cyhalothrin concentrations disappeared considerably faster from the water compartment compared to temperate conditions. Consistent decreases in abundance were observed for Lecane lunaris at the medium and higher treatments (NOEC = 9 ng/L) and at the highest treatment (NOEC = 30 ng/L) for Keratella tropica. On the contrary, two taxa belonging to Cladocera (i.e., Ceriodaphnia sp. and Diaphanosoma sp.) showed the most prominent increase in abundance related to the lambda-cyhalothrin treatments. At the community level, a consistent no observed effect concentrations (NOECs) of 9 ng/L could be calculated for the zooplankton community. A marginal significant overall treatment related effect was observed for the macroinvertebrate community. The results of species sensitivity distribution (SSD) analysis based on results of acute toxicity experiments conducted alongside the mesocosm experiment and obtained from the literature indicated that macroinvertebrates from temperate regions may be generally more sensitive than their counterparts in (sub-)tropical regions. Overall, these findings suggest that environmentally relevant concentrations of the pyrethroid insecticide lambda-cyhalothrin may lead to different ecological outcomes in freshwater ecosystems in the (sub-)tropics relative to temperate regions.

Fate and effects of an environmentally relevant mixture of microplastics in simple freshwater microcosms

Most studies assessing the effects of microplastics (MPs) on freshwater ecosystems use reference materials of a certain size, shape, and polymer type. However, in the environment, aquatic organisms are exposed to a mixture of different polymers with different sizes and shapes, resulting in different bioaccessible fractions and effects. This study assesses the fate and effects of an environmentally relevant mixture of high-density polyethylene (HDPE) fragments, polypropylene (PP) fragments, and polyester (PES) fibres in indoor freshwater microcosms over 28 days. The MP mixture contained common polymers found in freshwater ecosystems, had a size range between 50 to 3887 µm, and was artificially aged using a mercury lamp. The invertebrate species included in the microcosms, Lymnea stagnalis (snail) and Lumbriculus variegatus (worm), were exposed to four MP concentrations: 0.01, 0.05, 0.1 and 1% of sediment dry weight. MPs fate was assessed by performing a balance of the MPs in the surface water, water column, and sediment after a stabilization period and at the end of the experiment. Sedimentation rates per day were calculated, showing high dependency on polymer density (2.13% for PES, 1.46% for HDPE, 1.87% for PP). The maximum size of MPs taken up by the two species was determined and compared to the added mixture and their mouth size. The size range taken up by L. variegatus was smaller than L. stagnalis and significantly different from the size range in the added mixture. The No Observed Effect Concentrations (NOECs) for the reproduction factor of L. variegatus and the number of egg clutches produced by L. stagnalis were 0.01% and 0.1% sediment dry weight, respectively. The EC10 and EC50 for the same endpoint for L. stagnalis were 0.25% and 0.52%, respectively. This study shows that current MP exposure levels in freshwater sediments can result in sub-lethal effects on aquatic organisms, highlighting the importance of testing MP mixtures.

Acute and Chronic Ecotoxicity of Daphnia magna Exposed to Ash Leachate from the Cotopaxi Volcano, Ecuador.

Ecuador's wetlands and aquatic ecosystems are chronically exposed to ash contamination due to the frequent volcanoes' eruptions in the country. Still, the short and long-term effects of ash contamination on the aquatic biota are not well understood. We used ashes released by the Cotopaxi volcano in 2016 to investigate their acute and chronic effects in Daphna magna. We calculated the half maximal effective concentration (EC50) after 2 and 21 days of exposure, the non-observed effect concentration (NOEC), and the lowest observed effect concentration (LOEC) on offspring production. We also analyzed the metal concentration present in the ashes. The EC50 values at 2 and 21 days were found at 80% and 5% ash leachate concentrations, respectively. After 21 days of exposure, high mortality and low neonatal production were observed in all leachate concentrations (NOEC was at 15%, and LOEC was at 20% leachate concentration). Our results suggest that the ashes from the Cotopaxi volcano can cause acute and chronic toxicity to aquatic life and should be classified as hazardous waste, depending on the dose. There is an urgent need for further studies that assess toxicity caused by the intense volcanic activity in Ecuador.

Ecotoxicity of the chlorantraniliprole insecticide on Ceriodaphnia dubia

Studies on the toxic effects of pesticides to aquatic organisms are necessary to establish safe concentrations of exposure, promoting the protection of aquatic life. The insecticide chlorantraniliprole has been used since 2007 in several crops of vegetables and fruits, but despite its wide and continuous use, little ecotoxicological information is reported in the literature. Then, the objective of this work is to evaluate the ecotoxicological aspects of this insecticide in the test organism Ceriodaphnia dubia through toxicity tests, aiming at determining the values of NOEC (no observed effect concentration), LOEC values (lowest observed effect concentration), CV (chronic value) and EC(I)50, 48 h (acute effect concentration). The results indicated that C. dubia showed greater sensitivity when compared to other organismal groups exposed to the same insecticide, with EC(I)50, 48 h values of 2.9 ± 1.11 µg.L-1, NOEC of 0.61 ± 0.33 µg.L-1 and LOEC of 0.91 ± 0.49 µg.L-1. Based on toxicity tests with C. dubia and considering the protection of aquatic life, a safe environmental concentration of 0.74 µg. L-1 of the insecticide chlorantraniliprole is recommended.

Toxicity of the oil spilled on the Brazilian coast at different degrees of natural weathering to early life stages of the zebrafish Danio rerio

Toxicity of water accommodated fractions (WAF) from the oil spilled on the Brazilian coast at different stages of weathering were investigated using Danio rerio. Weathering stages included emulsified oil that reached the coast (OM) and oil collected 50 days later deposited on beach sand (OS) or adhered to shore rocks (OR). Parent and alkylated naphthalenes decreased whereas phenanthrenes increased from less weathered WAF-OM to more weathered WAF-OS and WAF-OR. More weathered WAF-OS and WAF-OR were more potent inducers of zebrafish developmental delay, suggesting that parent and alkylated phenanthrenes are involved. However, less weathered WAF-OM was a more potent inducer of failure in swim-bladder inflation than more weathered WAF-OS and WAF-OR, suggesting that parent and alkylated naphthalenes are involved. Decreases in heart rates and increased heart and skeletal deformities were observed in exposed larvae. Lowest observed effect concentrations for different developmental toxicity endpoints are within environmentally relevant polycyclic aromatic hydrocarbon concentrations.

Benchmarking produced water treatment strategies for non-toxic effluents: Integrating thermal distillation with granular activated carbon and zeolite post-treatment

The management of produced water (PW) generated during oil and gas operations requires effective treatment and comprehensive chemical and toxicological assessment to reduce the environmental risks associated with reuse or discharge. This study evaluated a treatment train that included a low-temperature thermal distillation pilot system followed by granular activated carbon (GAC) and zeolite post-treatment for processing hypersaline Permian Basin PW. Our study provides a unique and comprehensive assessment of the treatment efficiency considering a targeted chemical scheme together with whole effluent toxicity (WET) tests across four trophic levels regarding aquatic critical receptors of concern (ROC): Raphidocelis subcapitata, Vibrio fischeri, Ceriodaphnia dubia, and Danio rerio. The distillate from the thermal distillation process met various numeric discharge standards for salinity and major ions. However, it did not meet toxicity requirements established by the United States National Pollutant Discharge Elimination System program. Subsequent post-treatment using GAC and zeolite reduced the concentration of potential stressors, including volatile organics, NH3, Cd, Cr, Zn, and Mn in the final effluent to below detection limits. This resulted in a consistent toxicity reduction across all WET tests, with no observable adverse effects for R. subcapitata, C. dubia, and D. rerio (no observed effect concentration >100%), and V. fischeri effects reduced to 19%. This study realizes the feasibility of treating PW to non-toxic levels and meeting reuse and discharge requirements. It underscores the importance of implementing integrated treatment trains to remove the contaminants of concern and provides a systematic decision framework to predict and monitor environmental risks associated with PW reuse.

Mercury concentrations in Seaside Sparrows and Marsh Rice Rats differ across the Mississippi River Estuary

Mercury (Hg) concentrations and their associated toxicological effects in terrestrial ecosystems of the Gulf of Mexico are largely unknown. Compounding this uncertainty, a large input of organic matter from the 2010 Deepwater Horizon oil spill may have altered Hg cycling and bioaccumulation dynamics. To test this idea, we quantified blood concentrations of total mercury (THg) in Seaside Sparrows (Ammospiza maritima) and Marsh Rice Rats (Oryzomys palustris) in marshes west and east of the Mississippi River in 2015 and 2016. We also tested for a difference in THg concentrations between oiled and non-oiled sites. To address the potential confounding effect of diet variation on Hg transfer, we used stable nitrogen (δ15N) and carbon (δ13C) isotope values as proxies of trophic position and the source of primary production, respectively. Our results revealed that five to six years after the spill, THg concentrations were not higher in sites oiled by the spill compared to non-oiled sites. In both species, THg was higher at sites east of the Mississippi River compared to control and oiled sites, located west. In Seaside Sparrows but not in Marsh Rice Rats, THg increased with δ15N values, suggesting Hg trophic biomagnification. Overall, even in sites with the most elevated THg, concentrations were generally low. In Seaside Sparrows, THg concentrations were also lower than previously reported in this and other closely related passerines, with only 7% of tested birds exceeding the lowest observed effect concentration associated with toxic effects across bird species (0.2 µg/g ww). The factors associated with geographic heterogeneity in Hg exposure remain uncertain. Clarification could inform risk assessment and future restoration and management actions in a region facing vast anthropogenic changes.

Larval Biometry as an Endpoint in Chronic Sea Urchin Assays Echinometra lucunter (Linnaeus, 1758)

This study was carried out with the aim of contributing to the improvement of the evaluation of sea urchin embryo-larval tests, reducing its analysis subjectivity and also to solve the problems associated with the morphology of different Echinodermata larvae used in ecotoxicological tests. In this regard, the larval size technique (biometrics) was applied as an endpoint in sub-lethal assays using the reference toxicants zinc sulfate and potassium dichromate as a standard for calibrating the EC50 estimate (Median Effective Concentration) and NOEC (No Observed Effect Concentration). The tests, using the sea urchin species Echinometra lucunter, were carried out between the years 2017 to 2019 and were analyzed by two methods, the traditional one (counting normal larvae and those with developmental delay) and biometrics based on the maximum length of the larvae obtained in the treatments. It was established that the minimum number of measurements of the different stages of development (egg, embryo and larva) was 35 (n) per replicate. For the tests carried out over 15 months, it was verified, based on the Wald Test, that there is a seasonality in the sizes of the larvae. The EC50 of the metals tested was similar between the traditional and biometric methods when adopting the size of 18-hour-old larvae as a reference for 100% effect, but there was disagreement between the methods when the size of the eggs is considered as the total effect. On the other hand, the estimates of the NOEC were more sensitive by the biometry method, in disagreement with the traditional method.

Effects of the insecticide imidacloprid on aquatic invertebrate communities of the Ecuadorian Amazon

Imidacloprid is a neonicotinoid insecticide that has received particular attention due to its widespread use and potential adverse effects for aquatic and terrestrial ecosystems. Its toxicity to aquatic organisms has been evaluated in central and southern Europe as well as in (sub-)tropical regions of Africa and Asia, showing high toxic potential for some aquatic insects and zooplankton taxa. However, its toxicity to aquatic organisms representative of tropical regions of Latin America has never been evaluated. To fill this knowledge gap, we carried out a mesocosm experiment to assess the short- and long-term effects of imidacloprid on freshwater invertebrate communities representative of the Ecuadorian Amazon. A mesocosm experiment was conducted with five weekly applications of imidacloprid at four nominal concentrations (0.01 μg/L, 0.1 μg/L, 1 μg/L and 10 μg/L). Toxic effects were evaluated on zooplankton and macroinvertebrate populations and communities, as well as on water quality parameters for 70 days. Given the climatic conditions prevailing in the study area, characterized by a high solar radiation and abundant rainfall that resulted in mesocosm overflow, there was a rapid dissipation of the test compound from the water column (half-life: 4 days). The macroinvertebrate taxa Callibaetis pictus (Ephemeroptera), Chironomus sp. (Diptera), and the zooplankton taxon Macrocyclops sp., showed population declines caused by the imidacloprid treatment, with a 21-d Time Weighted Average No Observed Effect Concentrations (21-d TWA NOEC) of 0.46 μg/L, except for C. pictus which presented a 21-d TWA NOEC of 0.05 μg/L. In general terms, the sensitivity of these taxa to imidacloprid was greater than that reported for surrogate taxa in temperate zones and similar to that reported in other (sub-)tropical regions. These results confirm the high sensitivity of tropical aquatic invertebrates to this compound and suggest the need to establish regulations for the control of imidacloprid contamination in Amazonian freshwater ecosystems.

Cyclobutrifluram (TYMIRIUM® technology): Low risks of a soil applied nematicide and fungicide to non-target soil invertebrates and bees

Cyclobutrifluram (TYMIRIUM® technology) is a seed- and soil-applied nematicide and fungicide which protects the plant root mass. Cyclobutrifluram acts by inhibiting mitochondrial complex II electron transport and succinate dehydrogenase inhibition (SDHI). Concerns over the potential adverse effects on non-target species were addressed by assessing whether recommended field application rates of cyclobutrifluram would result in adverse impacts on soil invertebrates or honeybees. Studies conducted under laboratory conditions with the active ingredient and two formulations provided No Observed Effect Concentrations for earthworm (Eisenia andreii) reproduction of 71–171 mg a.i./kg dry soil with no effects on soil mite (Hypoaspis aculifier) reproduction. There were no effects on honeybee (Apis mellifera) adults or larvae following chronic exposure to doses up to 400 and 160 mg/kg diet respectively. Using Brazil as a target market (soybean seed treatment and in-furrow application in fruiting vegetables), our laboratory studies indicate that the risk to two species of soil invertebrates and honeybees of the use of cyclobutrifluram either in-furrow or as a seed treatment was orders of magnitude below any levels of concern.

Not all that glitters is gold: Glitter causes acute toxicity to nauplii of Artemia sp.

Glitter has been reported as a relevant pollutant, as it is widely used in cosmetic and textile products and craftwork, and often associated with domestic sewage. The particular glitter is composed of thin layers of plastic and metal. This study assessed the acute toxicity of glitter dispersions in the brine shrimp Artemia sp. Nauplii of Artemia sp. that were exposed to glitter dispersions (0.01, 0.1, 1, 10, and 100 mg/L), obtained by diluting a stock solution in seawater; the control consisted of filtered seawater only. Three replicates were used per treatment and consisted of glass tubes filled with 10 mL of the test solution, and ten nauplii aging over 48 h. After 48 h, the survivors were counted and examined under a microscope. The mean size of glitter particles was 3.94 (±0.98) µm; approximately 44 % of particles were in the range of very fine sand, and 27 % coarse silt. Significant lethal effects (p &lt; 0.05) occurred from 0.1 mg/L (Lowest Observed Effect Concentration - LOEC); the lethal concentration to 50 % organisms (LC50-48h) was 0.350 (0.348 - 0.351) mg/L. The exposed organisms also exhibited patches in their digestive tracts, and particles were stranded in their appendices. The results indicate the toxic potential of glitter to brine shrimp. This investigation indicates the need for further studies on the toxicity of glitter to marine invertebrates. Highlights Glitter includes particles of sizes similar to those of marine microalgae Exposure to glitter suspensions caused toxicity in brine shrimps from 0.1 mg/L The nauplii of Artemia were more sensitive to glitter than echinoderm embryos Metallic parts of the glitter were observed in the digestive tract of the brine shrimp nauplii

Comparing the effects and potencies of perchlorate and nitrate on amphibian metamorphosis using a modified amphibian metamorphosis assay (AMA).

A modified amphibian metamorphosis assay was performed in which Nieuwkoop and Faber (NF) stage 47 Xenopus laevis larvae were exposed to different concentrations of either perchlorate (ClO4 -) or nitrate (NO3 -) for 32 days. Larvae were exposed to 0.0 (control), 5, 25, 125, 625, and 3125 μg/L ClO4 -, or 0 (control), 23, 71, 217, 660, and 2000 mg/L NO3 -. The primary endpoints were survival, hind limb length (HLL), forelimb emergence and development, developmental stage (including time to NF stage 62 [MT62]), thyroid histopathology, wet weight, and snout-vent length (SVL). Developmental delay as evidenced by altered stage distribution and increased MT62, a higher degree of thyroid follicular cell hypertrophy, and an increase in the prevalence of follicular cell hyperplasia was observed at concentrations ≥125 μg/L ClO4 -. The no observed effect concentration (NOEC) for developmental endpoints was 25.0μg/L ClO4 - and the NOEC for growth endpoints was 3125 μg/L ClO4 -. Exposure to nitrate did not adversely affect MT62, but a decreasing trend in stage distribution and median developmental stage at ≥217 mg/L NO3 - was observed. No histopathologic effects associated with nitrate exposure were observed. An increasing trend in SVL-normalized HLL was observed at 2000 mg/L NO3 -. Nitrate did not alter larval growth. The NOEC for developmental endpoints was 71 mg/L NO3 -, and 2000 mg/L NO3 - for growth endpoints. The present study provided additional evidence that the effects and potency of nitrate and perchlorate on metamorphosis and growth in X.laevis are considerably different.

Evaluation of the ecological risk of pesticide residues from the European LUCAS Soil monitoring 2018 survey.

The 2018 LUCAS (Land Use and Coverage Area frame Survey) Soil Pesticides survey provides a European Union (EU)-scale assessment of 118 pesticide residues in more than 3473 soil sites. This study responds to the policy need to develop risk-based indicators for pesticides in the environment. Two mixture risk indicators are presented for soil based, respectively, on the lowest and the median of available No Observed Effect Concentration (NOECsoil,min and NOECsoil,50) from publicly available toxicity datasets. Two further indicators were developed based on the corresponding equilibrium concentration in the aqueous phase and aquatic toxicity data, which are available as species sensitivity distributions. Pesticides were quantified in 74.5% of the sites. The mixture risk indicator based on the NOECsoil,min exceeds 1 in 14% of the sites and 0.1 in 23%. The insecticides imidacloprid and chlorpyrifos and the fungicide epoxiconazole are the largest contributors to the overall risk. At each site, one or a few substances drive mixture risk. Modes of actions most likely associated with mixture effects include modulation of acetylcholine metabolism (neonicotinoids and organophosphate substances) and sterol biosynthesis inhibition (triazole fungicides). Several pesticides driving the risk have been phased out since 2018. Following LUCAS surveys will determine the effectiveness of substance-specific risk management and the overall progress toward risk reduction targets established by EU and UN policies. Newly generated data and knowledge will stimulate needed future research on pesticides, soil health, and biodiversity protection. Integr Environ Assess Manag 2024;20:1639-1653. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).