Environmental Toxicology and Chemistry最新文献

Because of the global concern about the environmental impacts of microplastic particles (MPs), scientifically defensible ecological risk assessments are increasingly required. However, such assessments remain challenging because of factors such as the diversity of MP characteristics (e.g., particle length and shape). In this study, we developed species sensitivity distributions (SSDs) for MPs using hierarchical Bayesian modeling, which accounted for intra-species variation as well as the influence of MP characteristics on chronic no observed effect concentrations (NOECs). We also incorporated highest observed no-effect concentrations (HONECs) into SSD estimation by appropriately treating them as right-censored data. Using data from a recently updated ecotoxicity database, we analyzed two datasets excluding HONECs (21 species) and including HONECs (33 species). For the HONEC-excluded dataset, the best SSD model, selected based on the widely applicable information criterion, included size category (<83 μm vs. ≥83 μm) and fiber shape, suggesting that smaller particles and fibers were associated with lower chronic NOECs. For the HONEC-included dataset, the best model included particle length and shape (fragment and fiber), indicating that shorter particle lengths and non-spherical shapes were linked to lower chronic NOECs. Median estimates of the hazardous concentration for 5% of species (HC5) ranged from 0.06 μg/L (fiber, particle length <83 μm) to 111 μg/L (non-fiber, particle length ≥83 μm) in the HONEC-excluded dataset. For the HONEC-included dataset, median HC5 estimates ranged from 0.003 to 167 μg/L depending on particle length and shape, while their 95% Bayesian credible intervals spanned approximately 5 to 7 orders of magnitude. Despite uncertainties in modeling, our SSD modeling framework provided a generalizable and data-informed approach to the incorporation of diverse MP characteristics and censored effect concentrations to improve ecological risk assessments for MPs as well as other substances.

Although the fish embryo acute toxicity (FET) test has been recognized as a potential alternative to the acute fish toxicity (AFT) test, further studies focusing on its applicability domain are required due to existing uncertainties. Improved prediction of the mode of action (MoA) could help to better define the applicability domain of the FET test. The Verhaar scheme is one of the currently used structure-based approaches for predicting MoA; however, it has limitations to define the MoA of chemicals. The objective of this study is to explore an approach for predicting the MoA of chemicals, with the aim of evaluating the applicability domain of the FET test. To this end, 40 chemicals, including three pesticides and seven pharmaceuticals with known biological targets, and 30 industrial chemicals without known biological targets were selected and the FET test and RTgill-W1 cell line assay were performed on these chemicals. Through the comparative analysis between the generated results and those from the AFT tests, it was demonstrated that an integrated approach that combines the results from several MoA prediction models can predict the applicability domain of the FET test more broadly than single-scheme approach through improved prediction of MoA. Furthermore, we explored a new effect-based approach for predicting MoA by comparing median lethal concentration (LC50) at the early and late developmental stages in the FET test. We found that the LC50 from 24 hr post-fertilization (24-hr LC50) in the FET test was similar to the median effect concentration from the cell line assay, indicating that 24-hr LC50 from the FET test mainly reflects basal cytotoxicity. These findings suggest that the ratio of the 24-hr LC50 to the 96-hr LC50 from the FET test may be useful for roughly predicting the MoA of chemicals, because the latter can include organ-specific toxicity, whereas the former mainly reflects basal cytotoxicity.

Flupyradifurone and sulfoxaflor are two novel insecticides registered for global use. They were developed as alternates to neonicotinoids, and their subsequent use restrictions, based on impacts on non-target organisms. Although structurally distinct, both alternatives share the same mode of action as neonicotinoids, raising concerns about their potential risks to non-target soil invertebrates. The fate and toxicity of flupyradifurone and sulfoxaflor in soil was assessed, tested both as pure chemicals and in commercial formulations (Sivanto™ Prime and Closer™ Insecticide, respectively). The half-life of flupyradifurone in soil ranged from 68 to 75 days for the commercial formulation (Sivanto™ Prime) and extended to 89 days as the pure chemical, reflecting the influence of adjuvants on degradation. In contrast, sulfoxaflor degraded rapidly with a half-life of only 2 to 3 days in soil for both the pure chemical and Closer™ Insecticide. Toxicity (adult survival and reproduction) was evaluated in three soil invertebrate species: Oppia nitens, Eisenia andrei, and Folsomia candida. No toxic effects were observed for O. nitens for all substances tested at the highest concentrations (≥15.5 mg a.i./kg dry soil) after a 28-day exposure. However, E. andrei was the most sensitive species to sulfoxaflor (median lethal concentration [LC50] = 0.25 mg/kg [pure chemical]; median inhibitory concentration [IC50] = 0.11 mg/kg [Closer™ Insecticide] and IC50 = 0.15 mg/kg [pure chemical]), with demonstrated bioaccumulation. Conversely, F. candida was the most sensitive to flupyradifurone, exhibiting significant effects on survival (LC50 <1.16 mg/kg [pure chemical]) and reproduction (IC50 <0.28 mg/kg [pure chemical]). Compared to neonicotinoids evaluated previously using the same test conditions, flupyradifurone and sulfoxaflor were less toxic than clothianidin to F. candida. However, sulfoxaflor was more toxic to E. andrei than thiamethoxam, clothianidin, and flupyradifurone.

Arsenic, a toxic metalloid widely distributed in nature, stands as one of the most hazardous environmental pollutants in estuarine and coastal ecosystems. The biotoxicity of arsenic is highly dependent on its chemical speciation and environmental conditions, where salinity acts as a critical factor that markedly influences its toxicological effects on aquatic organisms. To date, few studies have reported the combined effects of arsenic and salinity on fish, and the mechanisms of arsenic-induced toxicity on early fish development under varying salinity conditions remain poorly understood. In our study, the toxic effects of arsenic at different concentrations (0, 0.1, 1 and 10 mg/L) on the embryonic development of marine medaka (Oryzias melastigma) under three salinities (10, 20 and 30 ppt) were investigated. Our research results showed that arsenic exposure reduced the hatching rate of medaka embryos. At salinities of 10 and 20 ppt, the exposure to arsenic induced additional developmental toxicities, including decreased heart rate, shortened hatching time, increased malformation rate, and reduced body length of newly hatched larvae. Additionally, arsenic exposure altered the expression levels of cardiac development-related genes and immune-related genes, with varying expression changes observed across different salinity levels. These findings, taken together, demonstrate that salinity influences the arsenic-induced toxicity (cardiotoxicity, oxidative damage) on the embryonic development of medaka. Our study provides additional data support for the toxicity research and ecological risk assessment of arsenic in estuarine and coastal ecosystems.

Concerns have been raised regarding the findings and reproducibility of scientific research, including ecotoxicological studies. In environmental risk assessment, controlled laboratory or field-based exposure experiments are conducted to evaluate the effects of substances towards individual species or ecosystems. Exposure experiments generate crucial data but the process of collecting such data is both time-consuming and costly, with limited emphasis on ensuring reproducibility. The value of experimental data is immense and can have multiple applications or can be made fit for secondary scientific and regulatory use. Effective re-use of ecotoxicological experimental data is often hindered by (unintended) suboptimal reporting practices such as poorly described methodologies or inconsistent reporting of units or data. The purpose of this study is to highlight the issue of insufficient reporting in ecotoxicology through examples from publications as well as to provide solutions, focusing on how the data or metadata itself is reported rather than which variables are reported from experiments. Published data and metadata on nanomaterials, neonicotinoids and per- and polyfluoroalkyl substances (PFAS) were analyzed to gain insight into the extent to which insufficiently reported data is present across literature.

Perfluorooctane sulfonic acid (PFOS), a persistent and bioaccumulative per-and polyfluoroalkyl substance (PFAS), is widely distributed in aquatic environments and is known for its toxic effects. The present study investigated the toxicological mechanisms of PFOS in the bivalve Ruditapes decussatus under acute and subacute exposure scenarios, with particular emphasis on concentration-dependent and organ-specific responses in gills and digestive glands (DG). Clams were exposed to nominal PFOS concentrations under acute conditions (1-100 µg/ml for 5 days) and subacute conditions (1, 10, and 20 µg/ml for 15 days). Histological analyses revealed marked tissue-specific alterations, with gills exhibiting early structural damage and inflammatory responses, whereas the DG showed signs of contaminant accumulation and adaptive pathological changes. Biochemical analyses demonstrated significant oxidative stress at 20 µg/ml, evidenced by increased activities of catalase, superoxide dismutase, and glutathione S-transferase omega, together with elevated malondialdehyde and nitrite levels. Immunohistochemical analyses confirmed the activation of inflammatory and nitrosative pathways, with stronger responses in gill tissues. Overall, PFOS induced concentration-dependent and tissue-specific toxic effects, highlighting the gills as the primary target organ. These findings support the use of R. decussatus as a bioindicator species for assessing PFAS toxicity in marine environments.

Metal-contaminated soils generally contain mixtures rather than single metals. Laboratory toxicity tests often focus on single metals in soils freshly spiked with soluble metal salts, potentially overestimating bioavailability in field soils. This study determined the toxicity of mixtures of copper, zinc, cadmium and lead, dosed as chloride salts, to the springtail Folsomia candida in LUFA 2.2 soil that was either left as is after spiking, or leached to remove the chloride counterion. Effects on survival, growth and reproduction were related to total, 0.01 M CaCl2- and water-extractable metal concentrations in the soil and to internal concentrations in the springtails. Leaching the spiked soil adequately removed the counterion with relatively small metal losses. The sorption of cadmium and zinc to the soil decreased in the presence of other metals, whereas the sorption of copper and lead was not changed. Metal uptake by the springtails was not affected by the other metals, but decreased at high chloride concentrations. Leaching did not change metal uptake in the springtails, suggesting no direct influence of chloride competition. However, leaching reduced metal toxicity, except for cadmium. Mixture toxicity showed overall antagonism for all metal fractions and all endpoints, with dose ratio- and dose level-dependent deviations from concentration addition. The relative contribution of cadmium to the mixture was the most important factor associated with antagonism. Dose ratio-dependent deviations related to cadmium may be explained by its high toxicity combined with the large effect of other metals on its sorption. Changes in ecotoxicological effects and metal uptake at high mixture concentrations in unleached compared to leached soils suggest that chloride contributed to the toxicity of the metal salts and may explain the dose level-dependent deviations.

Per- and polyfluoroalkyl substances (PFAS) are a class of widespread, environmentally persistent compounds that pose a potential threat to wildlife and human health. Despite recent efforts to reduce the use of long-chain PFAS in industrial practices and commercial/consumer products, the persistence and solubility of PFAS have led to their detection in wildlife on a global scale. Osprey (Pandion haliaetus) have long been used as a sentinel species with an extensive history of serving as an effective bioindicator of contamination. Here we report on a large-scale evaluation of PFAS and potential health effects in osprey from the Chesapeake and Delaware Bays, USA. In 2011 and 2015, we collected plasma samples from osprey nestlings throughout the Chesapeake and Delaware Bay watersheds. We quantified 40 PFAS congeners in osprey plasma via liquid chromatography-mass spectrometry and analyzed plasma for indicators of immune and thyroid function, and plasma biochemistry. In all birds, perfluorooctanesulfonic acid (PFOS) was the most commonly detected PFAS, followed by perfluoroundecanoic acid, (PFUnA) and perfluorodecanoic acid (PFDA). In nestling plasma from Chesapeake Bay, PFOS tended to be a higher average contributor to PFAS profiles compared to samples from Delaware Bay. In contrast, long-chain perfluoroalkyl carboxylic acids (PFCAs) such as PFUnA and PFDA comprised larger percentages of total PFAS in osprey plasma from Delaware Bay relative to Chesapeake Bay. While some PFAS concentrations were associated with plasma health indicators, the proportion of variation explained was low. Overall, our study provides a more thorough understanding of PFAS presence in the Chesapeake and Delaware Bays and is one of the first to examine whether PFAS exposure is associated with adverse health effects in wildlife.

Chemical agents, such as sulfur mustard (SM), are extremely toxic, and prolonged exposure can severely disrupt the metabolism of amino acids and nucleic acids in organisms. To effectively monitor agent exposure and identify specific biomarkers, we employed 2-chloroethyl ethyl sulfide (2-CEES) as a simulant to investigate the changes in metabolic characteristics within three bryophytes under different concentrations of 2-CEES exposure. Key metabolic pathways and enzymes affected by 2-CEES were analysed using theoretical calculations. Results demonstrated significant morphological changes in bryophytes following exposure to 2-CEES. Meanwhile, Chlorophyll fluorescence parameters revealed that 2-CEES markedly disrupted the photosynthetic activity of Physcomitrella patens and Taxiphyllum taxirameum. Metabolomic analysis showed pronounced changes in metabolite expression after 72 hr of 2-CEES (600 mg/m³) treatment across all three species. Pathway enrichment analysis of differentially expressed metabolites (DEMs) indicated that 2-CEES significantly perturbed amino acid, nucleic acid, carbohydrate, and lipid metabolism in Bryum argenteum and Physcomitrella patens. In contrast, Taxiphyllum taxirameum exhibited primary disruptions in lipid metabolism, terpenoid and polyketide metabolism, and membrane transport. Notably, aberrant synthesis of L-Glutamyl-tRNA(Glu) in the aminoacyl-tRNA biosynthesis pathway may correlate with impaired chlorophyll production. In addition, the significant changes of Gamma-Glutamyl-beta-(isoxazolin-5-on-2-yl)alanine, Trans-zeatin riboside, and Cytidine in bryophytes exposed to 600 mg/m³ 2-CEES suggest their potential as micro- and trace biochemical indicators for agent-induced stress. Molecular docking of 2-CEES with key enzymes (Glutathione S-transferase and Glu-tRNA synthetase) revealed that its chloro and methyl groups form hydrogen bonds with residues such as TYR and ARG, interfering with substrate-binding activity and consequently disrupting metabolic pathways.