Environmental Toxicology and Chemistry最新文献

We compared the effects of lambda-cyhalothrin as the pure active ingredient and as a formulated product (Zero®), on the larval stage of the autochthonous species Boana pulchella. We evaluated ecotoxicological endpoints, behavioral and developmental alterations, and the biochemical detoxifying, neurotoxic, and oxidative stress responses, covering a wide concentration range from environmental to high application levels. Both pyrethroid preparations displayed similar ecotoxicity (median lethal concentration of ~0.5 mg/L), with the lethal effect of Zero® being more pronounced than that of the active ingredient. Sublethal behavioral alterations in natatory activity were observed at 1000 times lower concentrations, indicating the ecological hazard of tadpole exposure to this pyrethroid at environmentally relevant concentrations. Biochemical endpoints in B. pulchella larvae showed significant responses to lambda-cyhalothrin in the ng/L range; these responses were different for the pure or the formulated product, and they were variable at higher concentrations. Principal components analysis confirmed the prevalence of biochemical responses as early endpoints at the lowest lambda-cyhalothrin concentrations; the Integrated Biomarker Response Index proportionally increased with pyrethroid concentration in a similar way for the pure and the formulated products. We conclude that lambda-cyhalothrin is of concern from an environmental perspective, with particular emphasis on autochthonous anuran development. The battery of biochemical biomarkers included in our study showed a consistent integrated biomarker response, indicating that this is a potent tool for monitoring impacts on amphibians. Environ Toxicol Chem 2024;00:1-11. © 2024 SETAC.

Aromatic sensitizers and related substances (SRCs), which are crucial in the paper industry for facilitating color-forming and color-developing chemical reactions, inadvertently contaminate effluents during paper recycling. Owing to their structural resemblance to endocrine-disrupting aromatic organic compounds, concerns have arisen about potential adverse effects on aquatic organisms. We focused on SRC effects via the aryl hydrocarbon receptor (AHR), employing molecular docking simulations and zebrafish (Danio rerio) embryo exposure assessments. Molecular docking revealed heightened binding affinities between certain SRCs in the paper recycling effluents and zebrafish Ahr2 and human AHR, which are pivotal components in the SRC toxicity mechanism. Fertilized zebrafish eggs were exposed to SRCs for up to 96 h post fertilization; among these substances, benzyl 2-naphthyl ether (BNE) caused morphological abnormalities, such as pericardial edema and shortened body length, at relatively low concentrations (1 μM) during embryogenesis. Gene expression of cytochrome P450 1A (cyp1a) and ahr2 was also significantly increased by BNE. Co-exposure to the AHR antagonist CH-223191 only partially mitigated BNE's phenotypic effects, despite the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin being relatively well restored by CH-223191, indicating BNE's AHR-independent toxic mechanisms. Furthermore, some SRCs, including BNE, exhibited in silico binding affinity to the estrogen receptor and upregulation of cyp19a1b gene expression. Therefore, additional insights into the toxicity of SRCs and their mechanisms are essential. The present results provide important information on SRCs and other papermaking chemicals that could help minimize the environmental impact of the paper industry. Environ Toxicol Chem 2024;00:1-13. © 2024 SETAC.

Quantitative adverse outcome pathways (qAOPs) describe the response-response relationships that link the magnitude and/or duration of chemical interaction with a specific molecular target to the probability and/or severity of the resulting apical-level toxicity of regulatory relevance. The present study developed the first qAOP for latent toxicities showing that early life exposure adversely affects health at adulthood. Specifically, a qAOP for embryonic activation of the aryl hydrocarbon receptor 2 (AHR2) of fishes by polycyclic aromatic hydrocarbons (PAHs) leading to decreased fecundity of females at adulthood was developed by building on existing qAOPs for (1) activation of the AHR leading to early life mortality in birds and fishes, and (2) inhibition of cytochrome P450 aromatase activity leading to decreased fecundity in fishes. Using zebrafish (Danio rerio) as a model species and benzo[a]pyrene as a model PAH, three linked quantitative relationships were developed: (1) plasma estrogen in adult females as a function of embryonic exposure, (2) plasma vitellogenin in adult females as a function of plasma estrogen, and (3) fecundity of adult females as a function of plasma vitellogenin. A fourth quantitative relationship was developed for early life mortality as a function of sensitivity to activation of the AHR2 in a standardized in vitro AHR transactivation assay to integrate toxic equivalence calculations that would allow prediction of effects of exposure to untested PAHs. The accuracy of the predictions from the resulting qAOP were evaluated using experimental data from zebrafish exposed as embryos to another PAH, benzo[k]fluoranthene. The qAOP developed in the present study demonstrates the potential of the AOP framework in enabling consideration of latent toxicities in quantitative ecological risk assessments and regulatory decision-making. Environ Toxicol Chem 2024;00:1-12. © 2024 SETAC.

We investigated the occurrence and the environmental risk of eight contaminants of emerging concern (CECs; acetaminophen, naproxen, diclofenac, methylparaben, 17β-estradiol, sulfathiazole, sulfadimethoxine, and sulfamethazine) in three Brazilian water bodies, namely, the Monjolinho River Basin (São Paulo State), the Mogi Guaçu River (São Paulo State), and the Itapecuru River (Maranhão State) in three sampling campaigns. The CECs were only quantified in surface water samples collected at the Monjolinho River Basin. Acetaminophen, naproxen, and methylparaben were detected in the range of <200 to 575.9 ng L^-1, <200 to 224.7 ng L^-1, and <200 to 303.6 ng L^-1, respectively. The detection frequencies of the three measured compounds were between 33% and 67%. The highest concentrations of CECs were associated with intense urbanization and untreated sewage discharge. Furthermore, CEC concentrations were significantly correlated with total organic carbon, electrical conductivity, and dissolved oxygen levels, suggesting that domestic pollution from urban areas is an important source in the distribution of CECs in the Monjolinho River Basin. The environmental risk assessment indicated a high risk for acetaminophen (risk quotient [RQ] values between 2.1 and 5.8), a medium risk for naproxen (RQs between 0.6 and 0.7), and a low risk for methylparaben (RQs < 0.1) to the freshwater biota of the Monjolinho River Basin. Our findings show potential threats of CECs in Brazilian water bodies, especially in vulnerable areas, and reinforce the need for improvements in environmental regulations to include monitoring and control of these compounds in aquatic systems. Environ Toxicol Chem 2024;00:1-12. © 2024 SETAC.

Efforts to use transcriptomics for toxicity testing have classically relied on the assumption that chemicals consistently produce characteristic transcriptomic signatures that are reflective of their mechanism of action. However, the degree to which transcriptomic responses are conserved across different test methodologies has seldom been explored. With increasing regulatory demand for New Approach Methods (NAMs) that use alternatives to animal models and high-content approaches such as transcriptomics, this type of comparative analysis is needed. We examined whether common genes are dysregulated in Japanese quail (Coturnix japonica) liver following sublethal exposure to the flame retardant hexabromocyclododecane (HBCD), when life stage and test methodologies differ. The four exposure scenarios included one NAM: Study 1-early-life stage (ELS) exposure via a single egg injection, and three more traditional approaches; Study 2-adult exposure using a single oral gavage; Study 3-ELS exposure via maternal deposition after adults were exposed through their diet for 7 weeks; and Study 4-ELS exposure via maternal deposition and re-exposure of nestlings through their diet for 17 weeks. The total number of differentially expressed genes (DEGs) detected in each study was variable (Study 1, 550; Study 2, 192; Study 3, 1; Study 4, 3) with only 19 DEGs shared between Studies 1 and 2. Factors contributing to this lack of concordance are discussed and include differences in dose, but also quail strain, exposure route, sampling time, and HBCD stereoisomer composition. The results provide a detailed overview of the transcriptomic responses to HBCD at different life stages and routes of exposure in a model avian species and highlight certain challenges and limits of comparing transcriptomics across different test methodologies. Environ Toxicol Chem 2024;00:1-11. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Polar organic chemical integrative samplers (POCIS) are promising devices for measuring the time-weighted average concentrations of hydrophilic compounds in aquatic environments. However, the mechanisms underlying compound uptake by POCIS remain unclear. We investigated the permeation kinetics of polyethersulfone and polytetrafluoroethylene membrane filters, and the sorption kinetics of Oasis HLB (Waters), Envi-Carb (Supelco), and Oasis WAX (Waters) sorbents. The log octanol-water partition coefficient (K_OW) values of the 19 targeted compounds ranged from -0.55 to 6.0. The overall mass-transfer coefficients were negatively correlated with K_OW, indicating that interactions between hydrophobic compounds and the membrane inhibit permeation. The sorption rate coefficient showed no correlation with K_OW and depended on the type of sorbent used. These results imply that the uptake of highly hydrophilic compounds by POCIS is determined by both the membrane and the sorbent kinetics; however, membrane kinetics dominate the uptake of hydrophobic compounds. Environ Toxicol Chem 2024;00:1-7. © 2024 SETAC.

Traditional approaches for monitoring aquatic pollution primarily rely on chemical analysis and the detection of pollutants in the aqueous environments. However, these methods lack realism and mechanistic insight and, thus, are increasingly supported by effect-based methods, which offer sensitive endpoints. In this context, daphnids, a freshwater species used extensively in molecular ecotoxicology, offer fast and noninvasive approaches to assess the impact of pollutants. Among the phenotypic endpoints used, feeding rate is a highly sensitive approach because it provides evidence of physiological alterations even in sublethal concentrations. However, there has been no standardized method for measuring feeding rate in daphnids, and several approaches follow different protocols. There is a diversity among tests employing large volumes, extensive incubation times, and high animal densities, which in turn utilize measurements of algae via fluorescence, radiolabeling, or counting ingested cells. These tests are challenging and laborious and sometimes require cumbersome instrumentation. In the present study, we optimized the conditions of a miniaturized fast, sensitive, and high-throughput assay to assess the feeding rate based on the ingestion of fluorescent microparticles. The protocol was optimized in neonates in relation to the concentration of microplastic and the number of animals to increase reproducibility. Daphnids, following exposures to nonlethal concentrations, were incubated with microplastics; and, as filter feeders, they ingest microparticles. The new approach revealed differences in the physiology of daphnids in concentrations below the toxicity limits for a range of pollutants of different modes of action, thus proving feeding to be a more sensitive and noninvasive endpoint in pollution assessment. Environ Toxicol Chem 2024;00:1-11. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.