Environmental Toxicology and Chemistry最新文献

Wet-weather overflows (WWOs) of raw untreated wastewater have the potential to introduce elevated concentrations of ammonia and metals into aquatic environments for brief periods, varying from a few hr to several days. Existing risk assessment tools for discharges typically compare toxicant concentrations with guideline values and utilise direct toxicity assessments assuming continuous rather than pulsed exposures. In this study, the water flea, Ceriodaphnia dubia, was used for both continuous (8-day, equivalent to 192-hr) and pulse (6-hr and 24-hr) chronic toxicity assessments of wet-weather, rain-ingress, and diluted influent, as well as water samples from the downstream receiving streams of Darling Mills Creek (DMC) and Buffalo Creek (bc) in Sydney, Australia. As partial responses were missing in some exposure scenarios, model fitting and the use of Effect Concentration causing 10% response (EC10) values were deemed unreliable. Therefore, No-Observed Effect Concentration values were used instead. No-Observed Effect Concentration values for 6-hr and 24-hr pulse exposures were higher than those for continuous (8-d) exposure. When the concentrations of copper, zinc, and ammonia in pulse exposures were expressed as time-weighted average concentrations (TAC), they were found to be lower than those observed in continuous exposures to the same contaminants. The hazard quotient (HQ) was below 1 during pulse exposures. The estimated required dilutions of influent were a high 1 in 4 during continuous exposure but during 6-hr and 24-hr pulse exposures were considerably reduced to 1 in 1.25 to 2. This study enhances our comprehension of the toxicity associated with pulse contaminant exposures and contributes to the development of more effective approaches for the risk assessment and regulation of the more frequent (typical) short-duration sanitary sewer WWOs.

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, 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 low µg/L range with the lowest effect concentration (EC10) of 0.1 µg/L for A. tetracladia. Previous study points 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.

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 modelling using the "MixTox" model approach indicated this pattern was characterised 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. Modelling 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 modelled based on tissue concentrations, effects accord with additivity.

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 multisector balance, an approach that is unique amongst 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.

Obtaining PM2.5 samples that are consistent with the natural composition of PM2.5 is crucial for toxicological research. However, current extraction methods inevitably alter the physicochemical properties of PM2.5. Based on variations in processing procedures: extraction solvent (Water, Ethanol or dimethyl sulfoxide [DMSO]), sonication and filtration steps (coarse filtration with 40 μm filters and fine filtration with10 μm filters), five PM2.5 extraction methods were developed, designated as WSF10, ESF10, DSF10, DCF10, and DCSF10, respectively. A mathematical model was developed to evaluate the similarity of PM2.5 samples and the result showed that PM2.5 extracted by DCF10 method (Coarse filtration, Fine filtration, dissolved in DMSO) were closest to that of natural PM2.5, with the highest overall similarity value of 0.70 (0.70 ± 0.01). The cytotoxicity of DCF10-extracted PM2.5 were significantly higher than other groups, inhibiting BEAS-2B cell viability by up to 60% after 9 days exposure, which aligned best with the similarity results. The outcomes highlight that improper extraction methods may underestimate the actual toxicity of PM2.5. Therefore, optimizing and refining PM2.5 extraction protocols is critical for accurately evaluating its toxicity and providing valid evidence for health risk assessment.

Per-, and polyfluoroalkyl substances (PFAS) are a class of man-made chemicals that are widespread and persistent in the environment. Impacts of PFAS on the health of oysters are an emerging concern to conservationists and oyster farmers alike. Depuration of contaminants has been shown to be energetically expensive in some bivalves and there is concern that this metabolic cost may have a negative effect on organismal health. To address bioaccumulation concerns, eastern oysters (Crassostrea virginica) were exposed to a mixture of PFAS (PFOS, PFOA, PFHxA, PFPeA, PFBS) at a nominal concentration of 2 µg/L per compound for 28-days and then transferred to clean water for 5-days. Concentration of PFAS in soft tissues was measured on a subset of oysters seven times throughout exposure using an ultra-high performance liquid chromatography coupled to triple quadruple mass spectrometry (UHPLC-QqQ-MS) to determine PFAS bioaccumulation and subsequent depuration. Bioaccumulation factor was higher for >6 carbon chained compounds compared to <6 carbon chained compounds and PFAS tissue concentration was below detection limits within 24-hr of transfer to clean water. To determine metabolic cost of PFAS exposure and depuration, an additional group of oysters were exposed to either a mixture of PFOS + PFOA (5 µg/L each) or a mixture of PFOS, PFOA, PFHxA, PFPeA, PFBS (2 µg/L each) for 10-days and optical respirometry was used to assess changes in mass-specific oxygen uptake (MO2). There was no significant difference in MO2 between treatment and control oysters during exposure or during depuration. There was no evidence that exposure and depuration of PFAS mixtures at concentrations higher than measured in coastal environments adversely impacted oyster metabolism.

This study focuses on evaluating the relationship between the co-occurrence and speciation of trace metallic elements with reference to the acute toxicity observed to Daphnia magna. Calculations were performed on data from the regular monitoring of an industrial effluent. The effluent generally met regulatory discharge criteria for metal(loid)s (Fe > Zn > Al > Cu > Ni > As > Cd > Pb) concentrations, but sporadic toxicity was observed, indicating that the interactions between trace metallic elements might affect toxicity. The methodological approaches include correlation analyses (CA), one-way analyses of variance (ANOVA), principal component analyses (PCA), hierarchical cluster analyses (HCA), and geochemical calculations performed for the purpose of assessing trace metallic elements speciation. The results suggest that Cd and Cu are the primary contributors to toxicity while Fe could inhibit toxicity. Moreover, speciation calculations suggest that the bioavailable forms of Cd2+and Cu2+, even at sublethal levels, could play a pivotal role in the observed toxicity. The analyses of changes in correlations between pairs of elements in non-toxic versus toxic effluents further suggest synergistic Cu-Cd and antagonistic Fe effects on toxicity. The approach developed in the present study has the potential for wider implementation. The identification of statistical links between the concentrations of different contaminants and toxicity could facilitate toxicants identification, particularly for effluents that meet regulatory standards in terms of contaminant concentrations.

Environmental risk assessments (ERAs) of chemicals typically rely on standardized ecotoxicological tests that overlook inter-individual 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 impacting population dynamics and adaptability. However, the extent to which pollutants influence inter-individual variability and its population-level consequences remains poorly understood. To address this, our study examines the inter-individual 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 inter-individual growth rate variability. While the fungicide had a weak effect on the cohort's mean growth rate, we observed a three-fold increase in inter-individual variability in the exposed group. This increase highlighted a subset of highly sensitive individuals, whose growth was reduced by up to 10% compared to 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 ERA frameworks, improving safety factors for intraspecies variability, and defining regulatory thresholds. A better understanding of how contaminants affect inter-individual variation will enhance the accuracy and ecological relevance of risk assessments, ultimately capturing the long-term implications for population and ecosystem dynamics.

In acute fish toxicity tests, mortality has traditionally served as the primary endpoint. However, in accordance with the "3Rs" principle-replacement, reduction, and refinement-there is a growing need to minimize the suffering and pain experienced by test fish. In this study we aimed to establish a behavioral framework for identifying the moribund state in zebrafish (Danio rerio), providing a humane and ethically refined alternative endpoint. Continual observation of zebrafish exposed to ten representative chemicals allowed the documentation of twelve clinical signs, with severities of the signs evaluated using the death/clinical-sign ratio, which represents the proportion of fish exhibiting a given sign that subsequently died. The signs "immobility," "immobility at surface," and "lethargy" emerged as strong predictors of imminent death, each exhibiting a death/clinical-sign ratio of 1.0 across all tested chemicals and concentrations, indicating that all fish exhibiting these signs died within the 96-hr test period. Furthermore, the survival times from the onset of these signs to death were sufficiently short to justify their definition as moribund states. Accordingly, we defined these signs as moribund endpoints and propose that fish exhibiting any of them should be euthanized during the test period. Notably, these findings align with previously reported results in Japanese medaka, indicating the potential cross-species applicability of these moribund endpoints.

Aqueous film-forming foams (AFFFs) are widely used fire suppression products that have been identified as a direct source of environmental per- and polyfluoroalkyl substances (PFAS). Per- and polyfluoroalkyl substance exposure has demonstrated chronic and sub-lethal effects on biota. Ongoing efforts aim to reduce and, ideally, eliminate PFAS use in AFFF products. However, there is little known about the potential toxic effects of the new PFAS-free AFFFs, specifically on benthic organisms. The objective of this study is to quantify the effects of seven AFFFs on growth in the hard clam, Mercenaria mercenaria, over a 21-day exposure period with juvenile animals. Additionally, AFFF effects are reported from algal toxicity assays and a feeding study. Five of the PFAS-free AFFFs negatively impacted growth over the exposure period while one PFAS-free AFFF and the reference PFAS-containing AFFF had no observable effect. Median effect concentrations (EC50) for shell growth ranged from 5.81 mg/L to >100 mg/L. Clam dry and wet weights also decreased with increasing exposure concentration (p <0.05). Algal growth was impacted over a 96-hr exposure. Impacts were observed to final standing biomass and overall growth rates at the highest exposure concentrations. However, complete lethality was only observed for one PFAS-free product, suggesting lack of food availability was likely not the primary driver of growth inhibition for all products. Net particle clearance rates in AFFF exposed clams were not found to be impacted, suggesting there was no obvious AFFF influence on organismal feeding ability. The presented results identify chronic effects of exposure to these AFFFs in this economically and ecologically important bivalve species and is expected to inform decisions regarding PFAS replacement AFFF products.