Environmental Toxicology and Chemistry最新文献

{"title":"Development of a high throughput method for screening readily biodegradable chemicals.","authors":"Aina C Wennberg, Merete Grung, Malcolm Reid, Adam Lillicrap","doi":"10.1093/etojnl/vgaf236","DOIUrl":"https://doi.org/10.1093/etojnl/vgaf236","url":null,"abstract":"<p><p>Current standard test methods for assessing biodegradation of chemicals are laborious and not suited for high throughput screening of chemicals because of both the required volume of the test medium, and the limited possibility for automation of measurements of biodegradation. A high throughput method (HTM) should be miniaturized, suitable for automation, and be based on generic parameters that can indicate biodegradation of any chemical. The aim of this study was to develop a HTM based on bacterial proliferation (ie, growth) as an indicator of biodegradation, measured by flow cytometry. Natural bacterial communities were exposed to reference chemicals in 96-well plates for up to 14 days at 19 °C and the results compared to parallel standard biodegradation screening tests for freshwater (OECD 301F) and seawater (OECD 306). Increased bacterial growth, compared to non-exposed inoculums, was used as an indication of biodegradation. Sodium benzoate induced a significant growth response that corresponded to the biodegradation experiments in both freshwater and marine water. Aniline induced a lower frequency of significant growth compared to the frequency of positive biodegradation results, while caffeine induced a higher frequency and more rapid growth response compared to biodegradation results. This shows the potential for a HTM for biodegradation testing using bacterial growth.</p>","PeriodicalId":11793,"journal":{"name":"Environmental Toxicology and Chemistry","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145112095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dechlorination and Methylation of Tetrachlorobisphenol A in Hydroponic Pumpkin.","authors":"Ying Li, Yonglin Liu, Huiru Qiu, Weiliang Wang, Xiaoxuan Han, Weihao Xu, Lin Liu, Zhenxue Dai, Yong Tian","doi":"10.1093/etojnl/vgaf233","DOIUrl":"https://doi.org/10.1093/etojnl/vgaf233","url":null,"abstract":"<p><p>Tetrachlorobisphenol A (TCBPA) is widely used as an economical flame retardant and frequently detected in the environment. However, its bioaccumulation and metabolism in model organisms are unknown. Herein, pumpkin plants were hydroponically exposed to TCBPA to explore its metabolic behavior. The results indicated that TCBPA was absorbed and distributed throughout the plant, with the highest amount found in the roots (1860 ± 63 ng), followed by the stem (99.6 ± 10.9 ng) and leaves (11.8 ± 0.9 ng). TCBPA was absorbed by the roots from the hydroponic solution, subsequently translocated to the stem and leaves. The dechlorination product of TCBPA, Tri-CBPA, was detected in the roots (3.35 ± 0.87 ng) and stem (0.201 ± 0.018 ng), and its methylation product, TCBPA-MME, was also identified in the roots (122 ± 14 ng) and stem (2.03 ± 0.27 ng). TCBPA metabolites were predicted to be less toxic than TCBPA, indicating the potential use of pumpkin plants in TCBPA pollution remediation. The study findings clarify the absorption, migration, and transformation of TCBPA in a model organism, ie, pumpkin plants.</p>","PeriodicalId":11793,"journal":{"name":"Environmental Toxicology and Chemistry","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of the green microalga Chlorella sorokiniana for the removal of nutrients and of multiple antibiotics in wastewater treatment.","authors":"Ornrumpha Sethanunt, Thierry Tonon, J Brett Sallach, James P J Chong","doi":"10.1093/etojnl/vgaf235","DOIUrl":"https://doi.org/10.1093/etojnl/vgaf235","url":null,"abstract":"<p><p>Obtaining clean water is a global priority as emphasized by the United Nations Sustainable Development Goal 6, which aims to ensure availability and sustainable management of water and sanitation for all. Pharmaceutical pollutants are becoming more prevalent in aquatic environments, triggering public health concerns, negative environmental impacts, and the development of antibiotic resistance. Microalgae hold great potential for bioremediation of antibiotics, although most of the studies to date supporting these observations rely on conditions where artificial wastewater contained one or a few antibiotics. In the present study, Chlorella sorokiniana was used to assess the removal of a mixture of 10 antibiotics selected and tested considering environmentally relevant antibiotic concentrations based on data from the National Health Service (NHS, United Kingdom). The selected antibiotics had a risk quotient > 1 as calculated by the ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC). The experimental antibiotic concentration tested for each antibiotic corresponded to their PEC values. After 19 days of incubation, the β-lactam class (amoxicillin, penicillin V, cephalexin) showed the highest % of removal (51-85), followed by trimethoprim (24), oxytetracycline (6), metronidazole (6), and sulfamethoxazole (2). Different mechanisms, ie biodegradation, photodegradation, bioadsorption, and bioaccumulation, were involved at variable range. Increase in algal biomass was observed concomitantly to decrease in the concentration of the tested antibiotics, suggesting their use as a carbon source for cellular growth. In addition, levels of dissolved NH4+, NO3-, PO43-, and COD (chemical oxygen demand), decreased by 88, 22, 100, and 10%, respectively. Our study confirmed the ability of C. sorokiniana to biodegrade antibiotics while also effectively reducing key nutrient loadings.</p>","PeriodicalId":11793,"journal":{"name":"Environmental Toxicology and Chemistry","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of (Q)SAR models for screening of sea-dumped munition and related chemicals detected in environmental samples.","authors":"João Barbosa, Colin R Janssen, Hojun Lee, Taejun Han, Jihae Park, Jana Asselman","doi":"10.1093/etojnl/vgaf232","DOIUrl":"https://doi.org/10.1093/etojnl/vgaf232","url":null,"abstract":"<p><p>Following World Wars I and II, extensive dumping of conventional and chemical munitions in the marine environment has left a lasting impact on coastal areas, particularly those directly involved in the conflicts. Over the decades, corrosion of munition shells has resulted in the release and subsequent detection of a range of hazardous chemicals in environmental samples. These include conventional explosives and related chemicals (E&RC), as well as chemical warfare agents and related chemicals (CWA&RC). Despite this legacy, significant data gaps persist concerning the persistence, bioaccumulation and toxicity of these chemicals to human and environmental health. In this study, we applied updated and expanded suite of (Q)SAR tools-ECOSAR v2.2, EPI Suite v4.11, and OECD (Q)SAR Toolbox v4.5-to comprehensively and simultaneously screen and prioritize a broad range of both E&RC and CWA&RC chemicals detected in environmental samples from global munition dumpsites. To our knowledge, this is the first application of this combined, up-to-date toolchain to field-detected munition compounds. Our results demonstrate that (Q)SAR models can generate conservative estimations, useful for the prioritization of munition-related chemicals for further investigation, although the reliability for specific endpoints may vary depending on the available empirical data. We underline that TNT and its metabolites, followed by tetryl and picric acid (all E&RC), require urgent monitoring in the environment and seafood, alongside defined human health safety thresholds in key exposure sources. In addition, sulfur mustard, arsenicals CWA, and their metabolites should be prioritized for targeted human health and long-term environmental studies. This comprehensive screening approach addresses longstanding data gaps, providing a valuable framework for decision-makers engaged in the management and remediation of munition dumpsites.</p>","PeriodicalId":11793,"journal":{"name":"Environmental Toxicology and Chemistry","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of microplastics on survival, reproduction, and the microbiome of the freshwater oligochaete Tubifex tubifex.","authors":"Q P V Allamby, K A Kidd, R S Prosser","doi":"10.1093/etojnl/vgaf234","DOIUrl":"https://doi.org/10.1093/etojnl/vgaf234","url":null,"abstract":"<p><p>In freshwater ecosystems, particularly in riverine sediments, high levels of microplastics (MPs) (<5 mm) have been reported, potentially putting sediment-dwelling macroinvertebrates at risk. However, the effects of MPs on macroinvertebrates remain unclear, despite their critical roles in freshwater food webs. This study investigated whether exposure to three types of MPs (6 µm and 45 µm polystyrene microbeads, 100 µm polyethylene terephthalate (polyester) microfibers) causes adverse effects in the freshwater oligochaete, Tubifex tubifex. Worms were exposed across five environmentally relevant concentrations of each type of MP in sediment (negative control, 0.1, 1, 10, 100, and 1000 MPs per gram dry weight sediment). The exposures were also conducted using either pristine MPs or MPs that had first been colonized with biofilms. Survival of adult worms along with production of cocoons and juvenile worms were assessed following exposure to MPs for 28 days. Changes in the microbiota of whole oligochaetes and sediments were assessed using the V3-V4 regions of the 16S ribosomal RNA gene. Accumulation of MPs was examined after a gut clearance period to assess the ability of the worms to retain MPs. There were no statistically significant effects to survival or reproduction across all exposure concentrations and scenarios for the three types of MPs, along with no evidence of significant MPs accumulation. However, MPs exposure significantly altered host and sediment microbial communities, with effects varying by polymer type, particle size, and condition. In Tubifex tubifex, pristine 45 µm PS microbeads at the highest concentration increased Shannon diversity, while the highest concentration of biofouled 100 µm PET microfibers significantly altered beta diversity. In exposures using biofouled MPs, more differentially abundant bacterial genera were identified compared to pristine MPs, and included taxa linked to nutrient cycling and plastics degradation. In sediments, both alpha and beta diversity were significantly affected by 45 µm PS microbeads, and more differentially abundant bacteria were identified in these exposures compared to 100 µm PET microfibers. While chronic exposure to environmentally realistic MPs did not cause adverse effects to survival or reproduction in Tubifex tubifex, the consequences of alterations to the host microbiome due to MPs exposure requires further investigation.</p>","PeriodicalId":11793,"journal":{"name":"Environmental Toxicology and Chemistry","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Incorporation of metal speciation data into qicar models and application to data-poor technology-critical elements.","authors":"Séverine Le Faucheur, Jelle Mertens, Eric Van Genderen, Amiel Boullemant, Claude Fortin, Peter G C Campbell","doi":"10.1093/etojnl/vgaf230","DOIUrl":"https://doi.org/10.1093/etojnl/vgaf230","url":null,"abstract":"<p><p>In a previous paper we developed Quantitative Ion Character-Activity Relationships (QICARs) to relate the intrinsic properties of a metal to its acute toxicity towards freshwater aquatic organisms. These predictive tools were developed for a set of data-rich training elements and then applied to a representative selection of Technology-Critical Elements (TCEs). The toxicity of the TCEs was reasonably well predicted, with most values located within the 95% prediction intervals. In the present work we have extended this approach to use the calculated metal speciation. Linear Free Energy Relationships were used to estimate some of the needed thermodynamic constants. Using this information, we expressed the concentration resulting in a 50% effect level (EC50) values as free metal activities and performed the regression analyses. For the training metals, the determination coefficients slightly increased compared to those obtained using the total dissolved metal. As before, the log transformed composite value of the covalent index (χm  2r) was the best predictor of their acute toxicity towards algae and daphnids (χm = metal's electronegativity; r = ionic radius). However, for the TCEs the regressions were much poorer, particularly when the predicted free metal ion concentrations were very low (e.g., less than 10-18 M). We suggest that this result reflects the distinctive speciation of these metals, where (i) the free metal ion is present only at vanishingly low concentrations (the calculation of which is problematic), and (ii) in all but one case (Au(CN)2  -), the metal's calculated speciation is dominated by neutral polyhydroxo species (e.g., Au(OH)3  0, Ge(OH)4  0…). In our view, this result does not undermine the use of QICARs. Rather, the use of QICARs has revealed that the free-ion activity could be inadequate for predicting the toxicity of the studied data-poor metals.</p>","PeriodicalId":11793,"journal":{"name":"Environmental Toxicology and Chemistry","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of dietary selenium on the amphipod hyalella azteca and the midge chironomus dilutus.","authors":"John Besser, Danielle Cleveland, David D Harper, Rebecca Dorman, Aïda M Farag","doi":"10.1093/etojnl/vgaf231","DOIUrl":"https://doi.org/10.1093/etojnl/vgaf231","url":null,"abstract":"<p><p>Chronic selenium (Se) water quality criteria are based primarily on dietary organoselenium exposure and subsequent reproductive effects in fish. Available chronic Se toxicity data suggests that invertebrates are less sensitive than fish, but chronic invertebrate studies are limited. We evaluated yeast-based diets for chronic toxicity studies with Hyalella azteca and Chironomus dilutus. Growth and survival were similar among C. dilutus fed a yeast-only diet, a mixture of yeast and fish flake food, and a mixture of yeast and diatoms. Survival and growth of H. azteca were best in the yeast + diatom diet, so this diet was used for subsequent tests. In rangefinder tests, H. azteca 28-day survival, growth, and biomass, and C. dilutus 11-day survival were all significantly reduced at a dietary Se concentration of 49 µg/g dry weight, whereas C. dilutus growth and biomass were only affected at 200 µg/g dry weight Se. H. azteca had similar sensitivity to dietary Se in a 28-42-day chronic test-survival, growth, and biomass were significantly reduced at 44.5 µg/g dry weight Se. Dietary selenium reduced H. azteca reproduction by 75%-100% relative to Controls, but differences were not significant. Tissue Se EC10s were lower for H. azteca (9.0-23 µg/g dry weight) than for C. dilutus (11-56 µg/g dry weight). However, model evaluations suggest that the C. dilutus 11-day survival and H. azteca 42-day EC10s were less reliable than other endpoints. When tissue EC10s were converted to equivalent Se concentrations in fish tissue with a food web model, H. azteca (18 µg/g dry weight) and C. dilutus (68 µg/g dry weight) ranked 6th and 12th of 13 freshwater genera, respectively. Overall, these results suggest that the current U.S. Environmental Protection Agency tissue-based Se water quality criteria would be protective for fish and invertebrates and could be used for management of fishless waters.</p>","PeriodicalId":11793,"journal":{"name":"Environmental Toxicology and Chemistry","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AI-driven hazard prioritization of plastic additives using Tox21 bioassays and self-supervised graph transformers.","authors":"Donghyeon Kim, Eungyeong Lee, Youngmin Yi, Jinhee Choi","doi":"10.1093/etojnl/vgaf228","DOIUrl":"https://doi.org/10.1093/etojnl/vgaf228","url":null,"abstract":"<p><p>As plastics degrade into micro- and nano-sized particles, they can leach additive chemicals into the environment, potentially exerting greater toxicity than the polymer matrix itself. The ECHA Plastic Additives Initiative has compiled a list of more than 400 plastic additives that are used in high volumes. This study aimed to screen the potential toxicity of these chemicals using Tox21 bioassays and deep learning models. To this end, we collected the Tox21 dataset, which provides extensive bioactivity profiles for over 7,000 chemicals across various endpoints, including human nuclear receptor signaling and stress response pathways. We then trained deep learning models using experimental data from Tox21 bioassays. Specifically, we employed the GROVER algorithm, which was designed to overcome typical limitations of traditional graph neural networks by leveraging transformers and self-supervised pretraining. We fine-tuned the model on twelve Tox21 bioassay datasets, using the F1 score as the primary evaluation metric. As a result, the GROVER model outperformed baseline algorithms, including graph convolutional networks, random forest, support vector machines, and logistic regression. Using the fine-tuned GROVER models, we identified 78 highly active chemicals among 171 additives. For these active plastic additive chemicals, we also investigated existing hazard information (minimal oral point-of-departure) from the CompTox Chemical Dashboard and their Globally Harmonized System of Classification and Labelling of Chemicals (GHS) information from PubChem DB. This approach revealed significant data gaps for plastic additive chemicals with potential toxicity and can support regulatory decision-making. Collectively, this study provides a practical use case for applying cutting-edge AI models as new approach methodologies (NAMs) to modernize hazard assessment, in alignment with the 3Rs (Replacement, Reduction, Refinement) principle for animal testing.</p>","PeriodicalId":11793,"journal":{"name":"Environmental Toxicology and Chemistry","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A review on the biodegradation of textiles in the environment.","authors":"Olivia J Skilbeck, Richard S Blackburn, Paul Kay","doi":"10.1093/etojnl/vgaf229","DOIUrl":"https://doi.org/10.1093/etojnl/vgaf229","url":null,"abstract":"<p><p>Research on the environmental impact of textiles has grown in recent years although relatively scant attention has been given to the effects of the textile production process and environmental conditions on textile fates in the environment. Most work has focused on synthetic fibres, and where cellulosic materials have been studied, they have been assumed to be 'natural', despite textile production processes mean this is often not the case. This review article synthesises current work published on the biodegradation of fibres in the environment to guide future research in the field and better understand environmental fate. Biodegradation of cellulosic textile materials, ranges between 10-89% with variation measured between environments and textile characteristics. This is greater than reported for synthetic textiles (not exceeding 5% degradation). As has been reported in many studies of plastics in the environment, large variation exists in the reported biodegradation data due to differences in the methodologies used, particularly in terrestrial environments. Standardised methods have been widely applied to biodegradation studies which typically elevate temperatures and inoculate environments with microorganisms that would not naturally occur in natural environments. This had led to enhanced levels of biodegradation occurring in these experiments. Studies measuring biodegradation under more natural conditions, including lower temperatures and naturally occurring inoculums, have reported biodegradation 42% lower than when higher temperatures were maintained. Biodegradation has been reported to be reduced following the application of reactive dyes, water repellents, easy-care finishes and antimicrobial treatments. Consideration of the impact of chemical dyes and finishes on biodegradation levels is needed alongside environmentally representative biodegradation studies to develop a more in depth understanding of the environmental fate of microfibre pollution.</p>","PeriodicalId":11793,"journal":{"name":"Environmental Toxicology and Chemistry","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical and bioassay-based characterization of the growth promoter ractopamine in beef cattle manure.","authors":"J K Challis, Jenna Cantin, Jocelyn Thresher, Anthony W Curtis, Paul D Jones, Markus Brinkmann, Natacha Hogan, John P Giesy, Tim A McAllister, Francis J Larney","doi":"10.1093/etojnl/vgaf211","DOIUrl":"https://doi.org/10.1093/etojnl/vgaf211","url":null,"abstract":"<p><p>This study follows a previously published feeding trial investigating the fate of ractopamine and other veterinary-use pharmaceuticals in feedlot environments. Manure from these feeding trials was composted in windrows, stockpiled, and applied to soil to assess the fate and dissipation of ractopamine over 28 d. Concentrations of ractopamine increased over the first 2-4 d of composting and stockpiling, with concentrations as great as 2,500 ng/g dry weight (dw), before dissipating with a half-life of 5.7 d to concentrations <100 ng/g dw after 28 d (>95% treatment). Due to incorporation and dilution, manure-amended soils contained lesser initial concentrations of ractopamine (75 ng/g dw) and dissipated by ≈80% to < 10 ng/g dw after 28 d. Stockpiled manure extracts collected at Days 0, 4, and 28 d were tested for their (anti) estrogenicity and (anti) androgenicity using in vitro bioassays. Only estrogenicity was observed, with EC50 values ranging from 0.006-0.03 mg sample equivalents (SEQ) per mL. Relative to the positive control, 17β-estradiol, estrogen equivalents at the EC50 level (EEQ50, ng/g) of stockpiled manure ranged from 470 ± 50 ng/g at Day 0 to 80 ± 25 ng/g at Day 28. The presence of ractopamine in the manure had no impact on estrogenic potency. Endogenous hormones excreted by cattle are suspected to be the primary cause of observed estrogenic responses. However, trenbolone implants administered in ractopamine treated cattle 85 d prior to the described experiments contained estradiol, and thus likely also contributed to observed responses based on comparisons to non-implanted controls. Stockpiling manure reduced the estrogenic potency more than 5-fold, as indicated by increasing EC50 values over the 28 d study. The results presented here suggest that ractopamine is effectively dissipated during manure stockpiling and composting and is unlikely to pose any estrogenic or androgenic effects on agricultural environments when manures containing ractopamine are used as a fertilizer.</p>","PeriodicalId":11793,"journal":{"name":"Environmental Toxicology and Chemistry","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145085551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}