Environmental Toxicology and Chemistry最新文献

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.

The trophic magnification factor (TMF) is an important metric for evaluating chemical biomagnification in food webs. However, reported TMF values of cyclic volatile methylsiloxanes (VMS) vary widely, presumably due to the spatial gradient of chemical concentrations and sampling biases. This study surveyed biota and sediment concentrations of cyclic VMS and two reference polychlorinated biphenyls (PCBs; PCB-153 and PCB-180) in the rocky and sandy areas of the Yugawara coast, Japan. Biota concentrations and TMFs were also predicted by the Multibox-AQUAWEB model for the food webs in the same areas. The predicted biota concentrations and TMFs of the cyclic VMS and PCBs were in good agreement with the measured values. In the rocky and sandy areas, the mean TMFs of cyclic VMS were <1 with strong or moderate statistical significance, suggesting trophic dilution, while the mean TMFs of the PCBs exceeded 1 with strong statistical significance, indicating trophic magnification. The Multibox-AQUAWEB model was applied to predict TMFs for three cyclic VMS and five linear VMS in six global aquatic food webs: Lake Erie, False Creek, Lake Pepin, Lake Ontario, Inner Oslofjord, and Tokyo Bay. Predicted TMFs ranged from 0.13 to 1.00 for all VMS-food web pairs, except for L5 in Lake Pepin (TMF = 1.10; 95th percentile confidence interval [0.75, 1.61]), lacking statistical significance (p > 0.05). It is noted that none showed TMFs of VMS >1 with statistical significance. Thus, it is unlikely that VMS would be trophically magnified in aquatic food webs. To improve model predictions, more precise measurements of dietary uptake efficiencies and somatic biotransformation rate constants of VMS are needed, as trends against molecular weight or logKOW were not clearly demonstrated.

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals widely used as surfactants and repellents across industries such as textiles, personal care products, and nonstick cookware. In India, rapid industrialization and urbanization have increased PFAS usage, raising concerns about environmental contamination. Per- and polyfluoroalkyl substances are persistent, bioaccumulative, and have been detected in multi-environmental matrices including humans. This widespread contamination poses health risks to millions through water and food chains. Because PFAS usually occur as complex mixtures, comprehensive toxicity assessments addressing mixtures rather than individual compounds are urgently needed. The zebrafish (Danio rerio) is an established model for rapid toxicity screening and provides predictive insights into human health risks. This study evaluates developmental effects of two PFAS mixtures on zebrafish embryos and larvae: a 2-compound mixture (2-mix) consisting of perfluorooctanoic acid and perfluorobutanesulfonic acid, and a 24-compound mixture (24-mix) including long- and short-chain PFAS and their precursors. Developmental endpoints monitored were survival, hatching success, heart rate, and deformities. Morphometric analyses of head, eye, yolk sac, and pericardial areas were conducted with ImageJ. Oxidative stress was assessed via reactive oxygen species (ROS) quantification, and histopathology evaluated tissue alterations. Results revealed significant developmental toxicity, with the 24-mix causing delayed hatching, growth inhibition, blood accumulation, and reduced heart rate, whereas the 2-mix showed milder effects. Elevated ROS levels indicated oxidative stress in both groups, and histopathology confirmed damage to the eye, brain, and muscles. These findings demonstrate that prolonged exposure to environmentally relevant PFAS concentrations can induce significant biological effects. This study provides critical insights into PFAS mixture toxicity, informing risk assessments and guiding regulatory policy development to protect public health.

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.

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 to that of North American amphibians. Larvae were exposed to 6:2 FTS (1.2 to 1200 ppb) from Niewkoop and Faber (NF) stage 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 non-significant developmental delay at 120 ppb (38.0 ± 2.9 vs 35.5 ± 1.8 days to NF 65). The non-monotonic response yielded dual NOEC/LOEC interpretations: 1) Growth stimulation with a NOEC = 12 ppb and a LOEC = 120 ppb; and 2) Adverse effects with a NOEC = 1200 ppb). X. laevis sensitivity to 6:2 FTS appears comparable to North American native amphibians (reported NOECs: 800-1,800 ppb), though the stimulation response and lack of a dose-response complicates their application for assessing ecological risks. While 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 impact growth and development.

For more than two decades, the Research Institute for Fragrance Materials (RIFM; Mahwah, NJ, USA) has been at the forefront of conducting environmental risk screening assessments that help to ensure the safe use of all fragrance materials with reported use in consumer and commercial products. Salvito et al. (2002) introduced a tiered framework for prioritizing fragrance materials that enter aquatic systems via down-the-drain disposal in the United States and Europe. Given the global use of fragrance materials, there is a growing need to update the framework to better represent environmental risk screening across additional geographic regions. In this paper we describe an update to the framework that applies global exposure data, as well as advances in predictive tools for ecological hazard assessment and environmental fate models. We integrated advanced methods for predicting environmental concentrations of fragrance materials in wastewater and surface water by using modern wastewater treatment plant fugacity models and accounting for abiotic and biotic loss mechanisms. To rapidly screen low-volume and low-toxicity chemicals using a data-driven approach, we applied an ecological threshold of concern in the initial tiers of the framework. In combination, these practices yield a broadly applicable, efficient, yet conservative framework for prioritizing fragrance materials for additional data gathering. This framework will enable RIFM and manufacturers and suppliers of fragrance materials to support science-based decisions on fragrance material environmental safety.

The Amphibian Metamorphosis Assay (AMA) was established as a standardized test guideline with the primary purpose of evaluating test materials for potential endocrine activity in the hypothalamus-pituitary-thyroid axis of developing African clawed frogs (Xenopus laevis). The Extended Amphibian Metamorphosis Assay (EAMA) is similar to the AMA with a key difference in that the EAMA terminates at a fixed developmental stage (i.e., Nieuwkoop and Faber [NF] stage 62) rather than at the fixed exposure time of the AMA (i.e., 21 days). This study summarizes the control data at NF stage 62 for a total of 17 EAMAs conducted at two different laboratories. The EAMA termination endpoints, including wet body weight, snout-to-vent length, hind limb length, normalized hind limb length, and thyroid histopathology, as well as the time to reach NF stage 62, are summarized. The endpoints in the EAMA exhibited less variability in comparison to endpoints collected at termination (Day 21) in the AMA. Regression analyses were conducted for continuous endpoints taken at the termination of the EAMA. Wet body weight versus snout-to-vent length showed the highest mean coefficient of determination of R2 = 0.71. Time to NF stage 62 did not show a strong correlation to morphometric endpoints (R2 ≤ 0.40), which may reflect the plasticity of amphibian metamorphosis. Histopathological investigations of thyroid glands indicated that mild and moderate follicular cell hypertrophy and mild follicular cell hyperplasia occur regularly as a part of normal development among NF stage 62 control tadpoles. In summary, the control performance data of 17 EAMAs indicate a robust baseline that can be used to refine the performance criteria and aid in the interpretation of the results of future fixed-stage test designs.

This study investigated the effects of two emerging per- and polyfluoroalkyl substances (PFAS), perfluorododecane sulfonic acid (PFDoDS) and perfluoro-4-ethylcyclohexane sulfonic acid (PFECHS), alongside legacy perfluorooctanesulfonic acid (PFOS) on mallard ducklings (Anas platyrhynchos) exposed in ovo. These PFAS compounds were selected based on their detection in a declining sea duck species and concerns over their endocrine disruption potential. Farmed mallard eggs were injected with 80 ng/g of PFDoDS, PFECHS, or PFOS, simulating maternal transfer to the egg and reflecting concentrations at the upper end of those reported in wild bird eggs. Gene expression was assessed in the liver, heart, and bursa of Fabricius. In the liver, messenger RNA (mRNA) and small RNA sequencing revealed sex-specific changes in genes related to metabolism and immune function, particularly antiviral responses, in PFECHS- and PFDoDS-exposed ducklings. Notably, there was overlap between male PFECHS- and PFOS-exposed groups. In the heart, quantitative polymerase chain reaction (qPCR) analyses of mRNAs and microRNAs associated with stress, inflammation, and development showed no differences, though trends included altered expression of genes involved in oxidative and cellular stress responses across treatments. In the bursa of Fabricius, qPCR of immune-related mRNAs revealed upward trends in innate immune gene expression across all exposure groups, also consistent with antiviral immune activation, suggesting shared transcriptional effects among these sulfonated PFAS. These findings demonstrate that emerging PFAS exposure alters gene regulation related to key physiological pathways, with responses differing by sex and tissue type. Our results underscore the complexity of PFAS-induced immunomodulation and highlight potential developmental risks of maternal PFAS transfer in wild avian species.