Environmental Toxicology and Chemistry最新文献

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.

Fipronil is a phenylpyrazole pesticide extensively used in the domestic environment and in agriculture for insect control. Due to its relative stability in water, fipronil and its degradation byproducts, formed by the disinfection process of water with chlorine, have been detected in water sources used for human consumption. However, little is known about the toxicity of the byproducts formed by the chlorination of fipronil in higher organisms. Therefore, this work aimed to assess the subchronic toxicity (adult fish) of the byproducts formed from the chlorination of the pesticide fipronil in the zebrafish (Danio rerio) test organism. For this purpose, the animals were exposed to solutions containing standard fipronil (50 µg·L-1), standard fipronil degraded by chlorination (50 µg·L-1), commercial fipronil (50 µg·L-1), and commercial fipronil degraded by chlorination at concentrations of 10, 50, and 100 µg·L-1. In the subchronic test (28-60 days), macroscopic body alterations and liver histopathology were investigated. The results demonstrated a high degree of toxicity of the fipronil chlorination byproducts compared to the parent compound. Macroscopically, drastic alterations were observed in the spinal column of adult animals treated with these solutions. Microscopically, the main liver alterations observed were the presence of pyknosis and steatosis, both of which are early indicators of cell death. Fipronil chlorination byproducts demonstrate substantial toxicity in adult zebrafish, causing early liver lesions that highlight potential ecological and health risks associated with contaminated water.

Among the most crucial pollinators, managed honeybee (Apis mellifera) colonies frequently experience colony losses, which impose significant economic burdens on beekeeping and threaten the reliability of pollination services. Pesticide exposure is recognized as one stressor among others contributing to these losses. However, the curated harmonized dataset to characterize the impacts of multiple pesticides on different stages of honeybees is missing. To address this data gap, we generated an extensive and consistent honeybee ecotoxicity dataset of Top (Dermal)-Acute 10% effective dose (ED10) and Oral-Chronic ED10 from the U. S. Environmental Protection Agency (USEPA) Ecotoxicology Knowledgebase (ECOTOX databases) for Life Cycle Impact Assessment (LCIA) and other comparative assessments. Primary harmonization and standardization were conducted to resolve inherent inconsistencies in life stages, exposure types, effect types, units, endpoints, and test types. Subsequently, weighted linear regressions were applied to extrapolate various endpoints to a harmonized ED10-equivalent (ED10eq), with R2 ranging from 0.38 to 0.99. The resulting integrated datasets comprise 540 chemicals across Oral-Chronic, Oral-Acute, and Acute-Topical exposure scenarios, consistently spanning approximately 8 orders of magnitude for the adult groups and 6 orders of magnitude for the larval groups. Additionally, the relationship between Adult and Larva ecotoxicity data was analyzed, along with an uncertainty assessment for the Oral-Chronic and Top-Acute datasets, further enhancing the reliability and applicability of the harmonized data. These harmonized ecotoxicity datasets significantly enhance the LCIA framework by replacing the median effective dose (ED50) acute data with Oral-Chronic Top-Acute ED10 data, thus facilitating a more environmentally realistic assessment of pesticide impacts on honeybees.

Plant protection products (PPP) help growers minimise crop losses from pests. For their authorisation in Europe, environmental fate and behaviour must characterised, including possible transport via air, to assess the risk of potential impacts. Recent interest in airborne PPPs has significantly increased but there is a lack of standardisation in measurements and distinction between long-range transport and local off-target movement is often unclear in publications. In the present study, substance-deposition measurements from two bioindicator plants and bulk-deposition samplers, located at different sites in Bavaria, were used to elucidate aspects of different transport mechanisms. Bulk-deposition data, measured at an agricultural and a background site (≥3 km away from agricultural land) showed frequent pesticide detections. However, detection frequencies and measured concentrations in these samples (i.e., precipitation) were significantly lower at the background site compared with the agricultural site. At the background site, the highest measured deposition of a PPP substance corresponded to 0.007% of its maximum registered field-application rate. At the agricultural site, the highest measured deposition was attributed to local spray drift and represented 0.5% of the maximum field-application rate. Bioindicator plants showed that deposition was predominantly influenced by local agriculture, reflecting the extent of land use for the cultivation of different crops and, hence, the likely magnitude of local pesticide spraying. Observed peak depositions to bulk and bioindicator sampling systems corresponded in time with PPP application to crop fields. There was no clear correlation between the bulk- and bioindicator-plant deposition data sets. When investigating pesticide transport via air, special attention should therefore be placed in the selection of the measurement matrices and methodology to address specific research questions.

17α-ethinylestradiol (EE2) is a highly potent endocrine disrupting chemical (EDC) that pollutes aquatic ecosystems, leading to biological impairment in freshwater organisms such as Daphnia magna. Bioavailability of EE2 may be affected by the presence of dissolved organic matter (DOM), also found in aquatic ecosystems; however, these interactions are not fully understood. To address this, EE2 interactions with two DOM types with varying chemistry (Suwannee River [SR] DOM and Leonardite-derived DOM) are explored by examining molecular-level perturbations to the polar metabolic profile of D. magna. D. magna were acutely (48 hr) exposed to sublethal concentrations of EE2 (high = 1 mg/L and low = 0.1 mg/L) and mixtures of each DOM type. Targeted metabolomics using liquid chromatography-tandem mass spectrometry was used to measure 52 polar metabolites from individual adult daphnids. In the absence of DOM, EE2 exposure at both concentrations significantly affected key metabolites and pathways that are essential for growth and survival in D. magna. Exposure to the DOM-SR and EE2 mixture resulted in the highest number of significant metabolite and pathway perturbations, whereas exposure to the Leonardite DOM and EE2 mixture demonstrated the least disruptions. These results suggest that the Leonardite DOM likely lowered the bioavailability of EE2 through binding, whereas the DOM-SR enhanced metabolic disruptions. Thus, these findings affirm that different types of DOM can distinctively affect EE2 behavior and biological response at the molecular-level, highlighting the importance of considering DOM chemistry when examining its interactions with pollutants and subsequent impacts to aquatic organisms.

We evaluated the potential for activated carbon (AC) amendments to reduce the bioavailability of methylmercury (MeHg) in field-collected sediments. To do so, we adapted a standard 28-day bioaccumulation bioassay with the benthic invertebrate Leptocheirus plumulosus to address challenges associated with assessing the dynamic nature of MeHg biogeochemistry and the difficulty of testing a heavily vegetated marsh sediment. After method development, we compared the bioavailability of MeHg in unamended sediment, sediment amended with powdered AC, and sediment amended with the commercial AC product SediMite. A subsequent study compared the bioavailability of MeHg in unamended sediment, sediment freshly amended with AC, and sediment amended with AC almost 2 years prior to the start of this study. Activated carbon amendments consistently reduced the bioavailability of MeHg to L. plumulosus, as indicated by a 2- to 4-fold decrease in the biota-sediment accumulation factor, which normalizes tissue concentrations to sediment concentrations. However, AC amendments increased sediment MeHg concentrations in five of seven studies, apparently by altering the balance between MeHg production and degradation. As a result, the net effect of AC amendment on absolute concentrations of MeHg in amphipods was mixed, with moderate reductions at some time points in some experiments but increasing concentrations or no effect in other cases. The AC amendments significantly decreased Hg and MeHg in porewater in all cases, however. A literature review of biota-sediment accumulation factors for other studies was also conducted. The mechanisms by which AC influences the physical and biogeochemical drivers of net methylation and concentrations of MeHg in sediment remain unclear. Any potential use of AC for Hg remediation should undergo site-specific testing before implementation.

In the absence of a robust database of adverse effects to aquatic biota from pharmaceuticals introduced into the environment, alternate approaches are needed to assess risk. One such approach is the fish plasma model (FPM), which can be used to prioritize pharmaceuticals as a function of potential altered biological responses for fish exposed to these chemicals in receiving waters. Other published prioritization schemes assessing effects utilize quantitative-structure activity relationships, cellular assays, biochemical markers, and various apical effects. The FPM provides another line of evidence that is complementary to these approaches. We also examined potential effects due to human Ether-à-go-go-Related Gene activity for the active pharmaceutical ingredients (APIs) as another potentially useful and complementary approach for prioritization. In this study, we used the FPM to examine predicted effects for the most commonly prescribed pharmaceuticals, which allowed us to focus on the most environmentally relevant drugs potentially toxic to fish. Drugs with peak plasma concentration (Cmax) values were examined with a global database of surface water concentrations to predict potential risk for fish exposed to the most biologically active compounds. To prioritize the APIs most likely to cause adverse effects for fish, we limited the list to those with a response ratio ([plasma]/1%Cmax) ≥ 1 (n = 57) and those APIs without exposure concentrations exhibiting a 1%Cmax value ≤ 0.1 ng/ml (n = 50). The majority (n = 63) of the top prioritized APIs on this list fell into six drug classes: hormones (n = 21), antidepressants (n = 13), antihistamines (n = 8), anticholinergics (n = 4), corticosteroids (n = 4), and antihypertensives (n = 13). The FPM is advantageous because it is based on expected low-dose in vivo biological effects resulting from chemicals designed to interact with a specific target. Currently, the FPM is mostly limited to pharmaceuticals; however, this approach can be expanded to other chemicals with toxicity data expressed as a plasma concentration.