Environmental Toxicology and Chemistry最新文献

The per and polyfluoroalkyl substance (PFAS) precursor alternative, 6:2 fluorotelomer sulfonate (6:2 FTS), has been detected globally. The central aim of this work was to evaluate the chronic toxicity of 6:2 FTS for this understudied PFAS. Using the amphibian African clawed frog Xenopus laevis, we tested the main hypothesis that, regardless of sex, the sensitivity of this model to 6:2 FTS would be comparable with that of North American amphibians. Larvae were exposed to 6:2 FTS (1.2-1,200 ppb) from Niewkoop and Faber (NF) stages 51 to 65, which took a range of 24 to 42 days. We found significant growth stimulation at 120 ppb (26% mass increase, 6% snout-vent-length increase) without traditional dose-dependency. This growth stimulation coincided with a nonsignificant developmental delay at 120 ppb (38.0 ± 2.9 vs. 35.5 ± 1.8 days to NF 65). The nonmonotonic response yielded dual no observed effect concentration/lowest observed effect concentration (NOEC/LOEC) interpretations: (1) growth stimulation with a NOEC = 12 ppb and a LOEC = 120 ppb; and (2) adverse effects with a NOEC = 1,200 ppb. Xenopus laevis sensitivity to 6:2 FTS appears comparable with North American native amphibians (reported NOECs: 800-1,800 ppb), although the stimulation response and lack of a dose response complicates their application for assessing ecological risks. Although genetic sexing enabled sex-specific analysis in this species, no differences in sensitivity or accumulation rates were detected. These findings highlight the critical importance of endpoint selection in PFAS risk evaluation and supports previous findings with other amphibians showing that exposure to environmentally relevant 6:2 FTS concentrations should not adversely affect growth and development.

The Society of Environmental Toxicology and Chemistry (SETAC) is a global organization whose mission is the advancement of environmental science and management through collaboration, leadership, communication, and education. On SETAC's 45th anniversary, the following question was raised: Are the 1979 founding principles of SETAC, multidisciplinary approaches to solving environmental problems, multisector engagement, and scientific objectivity, still useful, adequate, and effective in fulfilling its mission? In a special session held at the 45th Annual Meeting in Fort Worth, Texas, United States, a critical evaluation of the founding principles was initiated by reviewing SETAC's history and ongoing activities, and recommendations were made for the future. With few exceptions, participants appreciated SETAC's purposeful efforts to approach challenging environmental issues through multisectoral balance, an approach that is unique among scientific societies. We recognized that scientists have biases and views of what they find important, regardless of employing organization, and that objectivity is best served by being aware of these biases and views. SETAC's founding principles have stood the test of time and continue to provide a strong foundation for the Society's mission, and with a few suggested improvements, will continue to be instrumental in guiding environmental science, stewardship, and policy into the future. The significance of SETAC's contribution of robust science grounded in reliable evidence and data was recognized as being especially crucial at this time of triple planetary crisis (climate change, pollution, and biodiversity loss), compounded by rapid technological developments and geopolitical issues.

Florpyrauxifen-benzyl (aquatic tradename ProcellaCOR) is an aquatic herbicide commonly used to control Eurasian watermilfoil (Myriophyllum spicatum) and other invasive aquatic plants. Previous studies have demonstrated effective Eurasian watermilfoil control under low aqueous concentrations (<10 µg L-1) and short exposure times (< 24 hr). Although florpyrauxifen-benzyl possesses an excellent environmental profile and its acute toxicity has been assessed in freshwater model organisms, there has been no work to examine toxicity of this herbicide in salmonids. Therefore, the objective of this study was to evaluate the acute toxicity to Endangered Species Act-listed Chinook salmon (Oncorhynchis tshawytscha). Chinook fry and smolts were exposed to florpyrauxifen-benzyl at 50 and 100 µg L-1 for 96 hr under a 24-hr static renewal protocol at 12 °C. Daily observations included fish startle response, position in the water column, and signs of overt toxicity. No adverse effects of the herbicide were observed at either concentration in both Chinook fry and smolts. Our results indicate that the maximum United States-labeled application rate of florpyrauxifen-benzyl (48 µg L-1 ai) did not result in overt toxicity to juvenile salmonids under the exposure scenarios used in this study.

Environmental risk assessments of chemicals typically rely on standardized ecotoxicological tests that overlook interindividual variability, despite its importance in ecological resilience and evolutionary success. Contaminants can disrupt individual differences by altering life history traits, amplifying fitness disparities, favoring certain phenotypes, and reducing genetic diversity, ultimately affecting population dynamics and adaptability. However, the extent to which pollutants influence interindividual variability and its population-level consequences remains poorly understood. To address this, our study examines the interindividual variability of growth trajectories in the earthworm Aporrectodea caliginosa in response to sublethal exposure to the two active substances of Swing Gold fungicide. Using a longitudinal design with 30 exposed and 30 unexposed individuals, we compared mean and interindividual growth rate variability. While the fungicide had a weak effect on the cohort's mean growth rate, we observed a 3-fold increase in interindividual variability in the exposed group. This increase highlighted a subset of highly sensitive individuals, whose growth was reduced by up to 10% as compared with the average response. Our results suggest that focusing solely on population mean effects could overlook impacts on sensitive individuals, who could serve as early indicators of environmental stress. Incorporating individual variability into ecotoxicological studies is challenging due to the labor-intensive nature of individual monitoring and the need for larger datasets. Nonetheless, these efforts are essential for refining higher-tier environmental risk assessment frameworks, improving safety factors for intraspecies variability, and defining regulatory thresholds. A better understanding of how contaminants affect interindividual variation will enhance the accuracy and ecological relevance of risk assessments, ultimately capturing the long-term implications for population and ecosystem dynamics.

Fludioxonil is an active principle used as a fungicide to prevent fruit rotting during cold storage. In the present study, we assessed the acute (96 hr) toxicity of the commercial formulation Scholar 23SC to embryos and larvae of the common South American toad (Rhinella arenarum), which inhabits the Alto Valle region in Neuquén and Río Negro, Argentina, an area of intensive fruit production. Scholar 23SC caused lethality in embryos and larvae, with median lethal concentration values of 0.355 mg/L and 1.382 mg/L, respectively. Scholar 23SC caused edema, tail flexure, and growth stunt in the developing embryos, with a median effect concentration value of 0.152 mg/L. In turn, larvae displayed swimming alterations and weakness but no malformations. We reviewed bibliographic data on fludioxonil toxicity to other species to perform a Species Sensitivity Distribution analysis, finding a hazardous concentration-5% (HC5) of 14 µg/L. In turn, from environmental concentration reports, we estimated exceedance probabilities of 5.8% for this HC5 and 13.4% when the lower confidence limit (1.75 µg/L) was used as a conservative criterion. Nevertheless, environmental determinations of fludioxonil concentration in irrigation channels of the Alto Valle region were at approximately the HC5 value. We conclude that Scholar 23SC was more toxic to R. arenarum embryos than larvae, and that the embryonic malformations and the larval behavioral alterations pose a threat to the individuals in a realistic environmental scenario as their performance would be hindered.

Mixture toxicity and bioavailability are important topics in ecotoxicological research. Here, we assess the role of bioavailability in determining the combined effects of two metals (Cd, Zn) on Eisenia andrei reproduction. When assessed based on total soil metal concentrations, a significant concentration ratio effect was seen. Mixture modeling using the "MixTox" model approach indicated this pattern was characterized by synergism when Zn was the metal at the highest concentration, changing to antagonism when Cd concentration was highest. Using 0.01 M CaCl2 extractable metal concentrations as the exposure metric, effects were also significantly different from additivity, predominantly being synergistic. This indicates that accounting for putative environmental availability did not explain the interaction. Metal analysis for this fraction indicated no effect of Cd on extractable Zn concentrations, but that Zn increased Cd extractability, potentially explaining the synergy. This bioavailability effect could be explained by replacement of Cd on soil binding sites by Zn, possibly enhanced by the formation of soluble Cd-Cl complexes resulting from increased Cl-counter ion presence with greater ZnCl2 addition. Modeling mixture effects based on earthworm tissue metal concentrations indicated no significant deviations from additivity. The tissue measurements indicated that internal Zn was not affected by soil total or extractable Cd levels. However, tissue Cd was strongly reduced by Zn. Such inhibition of Cd uptake could result from Zn competition with Cd at uptake sites and/or the formation of poorly bioavailable Cd-Cl species. Taken together, these mechanisms explain the concentration ratio dependent toxicity of Cd and Zn, why this is greatest when Cd dominates the mixture, and how, when effects are modeled based on tissue concentrations, effects accord with additivity.

In many crops, pesticides are applied simultaneously or sequentially, exposing soil microarthropods to dynamic residue mixtures. Yet, little is known about the possible ecological effects of such mixtures. This study investigated the effects of three commercial pesticides-clopyralid (herbicide), cypermethrin (insecticide), and pyraclostrobin (fungicide)-applied individually and in sequence on soil microarthropods (Collembola and Acari) in a field setting. Concurrently, standard laboratory tests were conducted to assess the toxicity of the individual pesticide formulations to the reproduction and survival of the Collembola Folsomia candida exposed in the same field soil. In the field, the formulations were applied individually and sequentially at 1× and 10× the recommended dose. Short-term (i.e., 1 week after application) and long-term effects (i.e., 4 weeks after application) on soil microarthropods were evaluated. In the laboratory, concentration-dependent reduction of F. candida survival and reproduction was observed only for pyraclostrobin and cypermethrin, with no-observed effect concentrations of 9.56 and 94.1 mg of active substance per kg dry soil, respectively. In the field, no aggravated effects of the sequential mixture were detected compared to the single pesticide applications. No negative short- or long-term effects were detected on Collembola abundance or diversity from any of the pesticides or their sequential mixture. In contrast, short-term exposure to the insecticide alone or in sequential mixtures significantly reduced Acari abundance in the field, though this effect weakened over time, leaving only a non-significant trend in the long term.

Aquatic hyphomycetes (AHs) are a group of fungi central for the decomposition of organic material in aquatic systems. Despite their ecological relevance, ecotoxicological studies involving AHs are fairly scarce. With the aim to better understand AH responses to changes in abiotic factors and increasing levels of contaminants, we explored their sensitivity in a multifactorial approach. Therefore, we assessed the radial growth response of three AH species (Alatospora acuminata, Articulospora tetracladia, and Tetracladium marchalianum) to three temperatures (12, 16, and 20 °C) and nutrient levels (0.0, 0.5, and 1.5% malt extract, w/v) in combination with increasing concentrations of the model fungicide trifloxystrobin (0 to 625 µg/L) over 21 days. The results showed a significant interaction between factors, with temperature being the most significant by potentiating trifloxystrobin toxicity for AH growth. The fungicide affected AH species in the low µg/L range with the lowest effect concentration of 0.1 µg/L for A. tetracladia. Previous study points to a regulatory acceptable concentration of 0.1 µg/L based on the ecotoxicological data of the most sensitive groups reported, which did not include AHs. Particularly in light of the ecological importance of them, their sensitivity to trifloxystrobin shown in our study highlights a fundamental concern when projecting the environmental risk of pesticides that directly affect aquatic fungi.

Neotropical stingless bees have frequently been reported to possess high biodiversity, ecological significance, and sensitivity to insecticides. Surprisingly, few studies have been conducted so far to assess their sensitivity to neonicotinoid insecticides, although there are indications that this insecticide class is especially toxic to stingless bees. The aim of this study was therefore to evaluate the acute oral and topical toxicity of two neonicotinoids, imidacloprid and thiamethoxam, to the neotropical stingless bee Melipona scutellaris. Besides these active ingredients, commercial products containing them were also evaluated. The commercial products were more toxic to the bees than the active ingredients, which may be due to direct toxicity of coformulants and indirectly through their higher biological activity and facilitation of uptake by organisms. The neonicotinoids were more toxic through topical contact than oral exposure. This is the opposite trend to that previously reported for honeybees, which is explained through differences in life-history traits with stingless bees. M. scutellaris was more sensitive to the test substances than standard bee test species commonly used in (temperate) toxicity assessments. This thus stresses the need to include stingless bees in neotropical risk assessments. The relatively high mortality occasionally observed in control groups highlights the biological sensitivity of stingless bees to laboratory conditions rather than a methodological flaw. This finding reinforces the importance of refining experimental setups by minimizing handling stress and improving cage microclimate to enhance control survival and ensure even greater robustness in future toxicity assessments involving native species.

Saponins are natural plant metabolites with surface-active and bioactive properties against plant pests, making them promising biopesticides. However, their environmental fate in soil remains unclear. This study investigated the sorption properties of three triterpenoid saponins, two monodesmosidic α-hederin and hederacolchiside A1 saponins, and the bidesmosidic hederacoside C saponin, on common soil constituents including clay minerals (kaolinite, montmorillonite), metal oxides (gibbsite, goethite), black carbon, and topsoil. Batch sorption experiments assessed influences of structures, sorbent properties, and environmental factors. All saponins exhibited unexpectedly strong sorption (distribution coefficient [Kd] > 10³ L/kg on topsoil), with α-hederin showing the highest affinity (Kd = 229 × 10³ L/kg on goethite), attributed to its moderate hydrophobicity (octanol-water partition coefficient, [log Kow] ∼ 4.4), short sugar chain, and interactions involving carboxyl (-COOH) and hydroxyl (-OH) functional groups. In contrast, more polar hederacoside C (log Kow ∼ -1.2) showed weaker sorption with Kd of 1.56 × 10³ to 22.7 × 10³ L/kg. Sorption isotherms followed Freundlich behavior and increased by approximately 50% at acidic pH for α-hederin and hederacolchiside A1 due to protonation of carboxylic acid groups (acid dissociation constant, pKa ≈ 4.7-4.9), whereas hederacoside C lacking carboxylic acid groups remained unaffected. Salts and fulvic acid reduced α-hederin sorption (up to 80%), likely due to ion exchange and competitive complexation. Desorption studies showed α-hederin was strongly retained (<20% desorption), particularly on metal oxides. Scenario-based modeling indicates that at realistic saponin biopesticide doses (50 µM), α-hederin and hederacolchiside A1 remain largely immobile, whereas hederacoside C may slightly leach in low-sorption soils. These findings highlight the combined role of saponin structure and soil mineralogy in regulating environmental mobility with implications for biopesticide design and risk assessment.