Toxics

14 pages, 2141 KiB

Open AccessArticle

Role of Environmental Photocatalysts and Organic Matter on the Degradation and Toxicity of Metformin Hydrochloride

by Rifat Khan, Jaqueline Regalado, Malsha Indeewari Kanaththage, Praveen L. Patidar and Gayan Rubasinghege

Toxics 2025, 13(5), 407; https://doi.org/10.3390/toxics13050407 (registering DOI) - 17 May 2025

Abstract

Metformin is the preferred first-line treatment for non-insulin-dependent diabetes mellitus, known for its benefits in cancer suppression, weight loss, and antiketogenic activity. It is a leading drug regarding mass distribution, and its high solubility in water leads to its significant accumulation in surface [...] Read more.

Metformin is the preferred first-line treatment for non-insulin-dependent diabetes mellitus, known for its benefits in cancer suppression, weight loss, and antiketogenic activity. It is a leading drug regarding mass distribution, and its high solubility in water leads to its significant accumulation in surface and groundwater. While some studies have explored its degradation products and toxicological consequences, none have specifically examined the impact of individual natural minerals and their mechanisms leading to these degraded compounds. Our investigation focuses on understanding the mineralogical effects of different photocatalysts and organic matter while assessing acute toxicity through cell viability tests on human cell lines. We utilized a custom-built reactor system containing metformin hydrochloride, photocatalysts, and organic matter under oxidizing conditions to explore the formation of new degraded compounds. We assessed the acute toxicity of both metformin hydrochloride and the resulting chemical mixture on kidney and liver cell lines using the colorimetric MTT cell viability assay. Despite the abundance of surface functional groups in organic humic acid, only solar energy-driven catalysts were found to effectively break down this widely used medication. Comparative analysis of metformin hydrochloride and its degraded residues indicates a toxic effect on liver cells. Our experiments contribute to understanding the environmental fate of metformin and pave the way for further biochemical investigations to identify toxicological mechanisms. Full article

(This article belongs to the Section Drugs Toxicity)

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13 pages, 2240 KiB

Open AccessArticle

Yucasin Alleviates Aluminum Toxicity Associated with Regulating Reactive Oxygen Species Homeostasis in Tomato Seedlings

by Huabin Liu, Chuangyang Bai, Jiahui Cai, Yue Wu and Changwei Zhu

Toxics 2025, 13(5), 406; https://doi.org/10.3390/toxics13050406 (registering DOI) - 17 May 2025

Abstract

The phytotoxicity of aluminum (Al) to plants is well known. Auxin accumulation and reactive oxygen species (ROS) burst induced by Al toxicity are the key factors in root growth inhibition. Yucasin, an auxin synthesis inhibitor, effectively ameliorates Al phytotoxicity in tomato seedlings. However, [...] Read more.

The phytotoxicity of aluminum (Al) to plants is well known. Auxin accumulation and reactive oxygen species (ROS) burst induced by Al toxicity are the key factors in root growth inhibition. Yucasin, an auxin synthesis inhibitor, effectively ameliorates Al phytotoxicity in tomato seedlings. However, the physiological mechanisms by which yucasin alleviates Al phytotoxicity in tomatoes remain elusive. Here, we examined the regulatory mechanisms of yucasin involved in tomato seedling growth under Al conditions through phenotypic, plant physiology analysis, and cellular experiments. Exogenous indole-3-acetic acid (IAA) application increased Al accumulation in tomato seedling roots, while yucasin decreased Al accumulation. Yucasin application reduced Al-induced ROS accumulation, lipid peroxidation, and cell death, enhanced root viability, and promoted tomato seedling root growth. Further, yucasin enhanced the antioxidant enzyme activities of superoxide dismutase, catalase, and peroxidase in plants under Al conditions. The results suggest that yucasin improves the scavenging capacity of ROS by maintaining the activities of antioxidative enzymes. This study elucidates the physiological mechanism by which yucasin alleviates Al phytotoxicity, highlighting its potential to enhance plant tolerance under acidic Al conditions. Full article

(This article belongs to the Section Toxicity Reduction and Environmental Remediation)

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19 pages, 1306 KiB

Open AccessArticle

Biodegradation of Benzo(a)pyrene in Contaminated Soil: Plant and Microorganism Contributions from Isotope Tracing

by Jianlong Wang, Xiaobing Su, Changhe Zhang, Zhimeng Han and Meiqi Wang

Toxics 2025, 13(5), 405; https://doi.org/10.3390/toxics13050405 (registering DOI) - 16 May 2025

Abstract

Biological degradation effectively removes benzo(a)pyrene (BaP) from contaminated soil; however, knowledge regarding the contributions of plant absorption, microbial degradation, and volatilization to BaP removal remains limited. In this study, the BaP removal pathway in contaminated soil was investigated. The structural evolution of the [...] Read more.

Biological degradation effectively removes benzo(a)pyrene (BaP) from contaminated soil; however, knowledge regarding the contributions of plant absorption, microbial degradation, and volatilization to BaP removal remains limited. In this study, the BaP removal pathway in contaminated soil was investigated. The structural evolution of the microbial community in contaminated soil was revealed using a comparative experimental study. BaP, as a representative of high-molecular-weight polycyclic aromatic hydrocarbons, was removed from freshly contaminated soil by microbial degradation, plant absorption, and volatilization in proportions of 20.955%, 12.771%, and 0.005%, respectively. The proportions of BaP removed by microbial degradation, plant absorption, and volatilization in aged contaminated soil were 29.471%, 16.453%, and 0.004%. Microbial degradation was the most responsible mechanism for BaP removal. Moreover, a higher number of BaP degrading bacteria occurred in the aged contaminated soil. At the genus level, Pseudomonas and Sphingomonas were detected in both types of soils, being the key bacterial species involved in BaP degradation. Full article

(This article belongs to the Section Toxicity Reduction and Environmental Remediation)

20 pages, 2510 KiB

Open AccessReview

Challenges in Toxicological Risk Assessment of Environmental Cadmium Exposure

by Soisungwan Satarug

Toxics 2025, 13(5), 404; https://doi.org/10.3390/toxics13050404 - 16 May 2025

Abstract

Dietary exposure to a high dose of cadmium (Cd) ≥ 100 µg/day for at least 50 years or a lifetime intake of Cd ≥ 1 g can cause severe damage to the kidneys and bones. Alarmingly, however, exposure to a dose of Cd [...] Read more.

Dietary exposure to a high dose of cadmium (Cd) ≥ 100 µg/day for at least 50 years or a lifetime intake of Cd ≥ 1 g can cause severe damage to the kidneys and bones. Alarmingly, however, exposure to a dose of Cd between 10 and 15 µg/day and excretion of Cd at a rate below 0.5 µg/g creatinine have been associated with an increased risk of diseases with a high prevalence worldwide, such as chronic kidney disease (CKD), fragile bones, diabetes, and cancer. These findings have cast considerable doubt on a “tolerable” Cd exposure level of 58 µg/day for a 70 kg person, while questioning the threshold level for the Cd excretion rate of 5.24 µg/g creatinine. The present review addresses many unmet challenges in a threshold-based risk assessment for Cd in the human diet. Special emphasis is given to the benchmark dose (BMD) methodology to estimate the Cd exposure limit that aligns with a no-observed-adverse-effect level (NOAEL). Cd exposure limits estimated from conventional dosing experiments and human data are highlighted. The results of the BMDL modeling of the relationship between Cd excretion and various indicators of its effects on kidneys are summarized. It is recommended that exposure guidelines for Cd should employ the most recent scientific research data, dose–response curves constructed from an unbiased exposure indicator, and clinically relevant adverse effects such as proteinuria, albuminuria, and a decrease in the estimated glomerular filtration rate (eGFR). These are signs of developing CKD and its progression to the end stage, when dialysis or a kidney transplant is required for survival. Full article

(This article belongs to the Special Issue Occupational and Environmental Exposures, Diseases and Epidemiology: From Basic Research to Human Health)

23 pages, 10071 KiB

Open AccessArticle

Spatial Variation Characteristics of Polycyclic Aromatic Hydrocarbons and Their Derivatives in Surface Water of Suzhou City: Occurrence, Sources, and Risk Assessment

by Jinxu Fan, Zhangwei Jing, Feng Guo, Jing Jia, Yu Jiang, Xiaoyu Cai, Shuting Wang, Hu Zhao and Xianjing Song

Toxics 2025, 13(5), 403; https://doi.org/10.3390/toxics13050403 - 16 May 2025

Abstract

Polycyclic aromatic hydrocarbons (PAHs) and their substituted derivatives (SPAHs) are persistent organic pollutants derived from incomplete combustion of fossil fuels and industrial processes. These compounds are of global concern due to their carcinogenicity and environmental persistence. This study provides the first comprehensive analysis [...] Read more.

Polycyclic aromatic hydrocarbons (PAHs) and their substituted derivatives (SPAHs) are persistent organic pollutants derived from incomplete combustion of fossil fuels and industrial processes. These compounds are of global concern due to their carcinogenicity and environmental persistence. This study provides the first comprehensive analysis of PAH and SPAH contamination in Suzhou’s rapidly urbanizing watersheds, integrating ultra-high-performance liquid chromatography and high-resolution mass spectrometry with multidimensional risk assessment to address critical gaps in understanding pollutant dynamics in urban aquatic systems. Key findings reveal that SPAHs were significantly more abundant than parent PAHs (mean ∑19 SPAHs = 107.43 ng/L vs. ∑8 PAHs = 48.05 ng/L), with hydroxylated derivatives accounting for 67.9% of the total SPAHs, indicating active environmental transformation processes. Source apportionment identified coal combustion and industrial emissions as the dominant contributors (58.2% of PAHs), directly linking contamination patterns to localized anthropogenic activities. Notably, industrial zones exhibited unexpected toxicity hotspots, where SPAH toxicity equivalents (e.g., 3-OH-BaP) surpassed parent PAHs 2–5-fold, demonstrating substituent-driven toxicity enhancement—a critical finding for regulatory prioritization. This study advances the field by uncovering SPAHs as emerging risks in urban waterways, challenging traditional PAH-centric monitoring frameworks, and providing a novel integration of analytical chemistry and spatial risk mapping to guide targeted pollution control (e.g., prioritizing industrial discharges and non-exhaust traffic emissions). Furthermore, it highlights the urgent need for updated toxicological databases to account for substituted PAH derivatives and advocates for the regulatory inclusion of SPAHs. These insights underscore the necessity of adapting environmental policies to address complex pollutant mixtures in rapidly developing regions, emphasizing the replicability of the proposed framework for urban watershed management. Full article

(This article belongs to the Special Issue Exploring Toxicity, Metabolism, and Transformation of Organic Pollutants)

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18 pages, 6073 KiB

Open AccessArticle

Preparation of Nitrogen-Doped Biochar and Its Adsorption Performance for Cr⁶⁺ and Pb²⁺ in Aqueous Systems

by Yazhai Zhang, Zhilei Xia, Aainaa Izyan Nafsun and Weiying Feng

Toxics 2025, 13(5), 402; https://doi.org/10.3390/toxics13050402 - 16 May 2025

Abstract

Toxicity and pollution of heavy metals in water environments are very serious threats, and how to efficiently remove heavy metals is a difficult problem in water ecosystems. This study takes Cr and Pb as examples to study the adsorption effects of different types [...] Read more.

Toxicity and pollution of heavy metals in water environments are very serious threats, and how to efficiently remove heavy metals is a difficult problem in water ecosystems. This study takes Cr and Pb as examples to study the adsorption effects of different types of modified biochar on these two heavy metals and their influencing mechanisms, with the aim of providing precise treatment schemes for water ecological health. Biochar was prepared from apricot branches, apricot shells, and corn stalks through nitrogen doping modification, and its structure and properties were characterized and analyzed. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were employed to investigate the microstructure and surface chemical characteristics of the biochar. Adsorption experiments were conducted to evaluate its removal efficiency for Cr⁶⁺ and Pb²⁺ from aqueous solutions. The results showed that nitrogen-doped biochar prepared from corn stalks at 600 °C exhibited the highest Cr⁶⁺ adsorption rate of 81.09%, while the biochar prepared at 500 °C demonstrated the highest Pb²⁺ adsorption rate of 91.61%. Comparative analysis of FTIR and SEM data between nitrogen-doped biochar and its original counterparts revealed the underlying adsorption mechanisms, which involve a synergistic effect of coordination interaction, electrostatic attraction, and chemical reduction. This study highlights nitrogen-doped biochar as an efficient and cost-effective material for the removal of heavy metal ions from aqueous environments. It also provides theoretical and practical insights into the resource utilization of agricultural waste and the management of water pollution. Full article

(This article belongs to the Section Toxicity Reduction and Environmental Remediation)

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36 pages, 4890 KiB

Open AccessArticle

Pulmonary Toxicity of Long, Thick MWCNT and Very Long, Thin Carboxylated MWCNT Aerosols Following 28 Days Whole-Body Exposure

by Chang Guo, Matthew D. Wright, Alison Buckley, Adam Laycock, Trine Berthing, Ulla Vogel, Frédéric Cosnier, Laurent Gaté, Martin O. Leonard and Rachel Smith

Toxics 2025, 13(5), 401; https://doi.org/10.3390/toxics13050401 - 16 May 2025

Abstract

Pulmonary exposure to carbon nanotubes (CNTs) has been linked to a series of adverse respiratory effects in animal models, including inflammation, genotoxicity, fibrosis, and granuloma formation, the degree and characteristics of which are considered dependent upon the detailed physicochemical properties of the material [...] Read more.

Pulmonary exposure to carbon nanotubes (CNTs) has been linked to a series of adverse respiratory effects in animal models, including inflammation, genotoxicity, fibrosis, and granuloma formation, the degree and characteristics of which are considered dependent upon the detailed physicochemical properties of the material as inhaled. To further explore the effect of variations in physicochemical properties on pulmonary effects, two different multi-walled CNTs (MWCNTs) were tested in vivo: a pristine MWCNT (pMWCNT) (NM-401) and a surface-modified MWCNT (MWCNT-COOH). Female Sprague–Dawley rats were whole-body exposed for 28 days to MWCNT aerosols (pMWCNT (0.5 and 1.5 mg/m³) and MWCNT-COOH (1.5 and 4.5 mg/m³)) and followed up to 1 year post-exposure. The inhalation exposures resulted in relatively low estimated lung deposition. Bronchoalveolar lavage fluid (BALF) analysis indicated inflammation levels broadly consistent with deposited dose levels. Lung histopathology indicated that both MWCNTs produced very limited toxicological effects; however, global mRNA expression levels in lung tissue and BALF cytokines indicated different characteristics for the two MWCNTs. For example, pMWCNT but not MWCNT-COOH exposure induced osteopontin production, suggestive of potential pre-fibrosis/fibrosis effects linked to the higher aspect ratio aerosol particles. This is of concern as brightfield and enhanced darkfield microscopy indicated the persistence of pMWCNT fibres in lung tissue. Full article

(This article belongs to the Section Human Toxicology and Epidemiology)

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23 pages, 2087 KiB

Open AccessReview

Sources, Status, and Potential Risks of Microplastics in Marine Organisms of the Bohai Sea: A Systematic Review

by Jian Yang, Hongxia Li, Wei Ling, Yifei Li, Kangkang Zhang and Pu Zhang

Toxics 2025, 13(5), 400; https://doi.org/10.3390/toxics13050400 - 16 May 2025

Abstract

This study focused on microplastic pollution in the Bohai Sea, employing bibliometric analysis and meta-integration methods to systematically analyze its pollution characteristics and ecological risks. The results indicated that microplastics primarily originated from land-based inputs (62%) and marine activities (23%). Microplastic concentrations in [...] Read more.

This study focused on microplastic pollution in the Bohai Sea, employing bibliometric analysis and meta-integration methods to systematically analyze its pollution characteristics and ecological risks. The results indicated that microplastics primarily originated from land-based inputs (62%) and marine activities (23%). Microplastic concentrations in the Bohai Sea’s coastal areas were significantly higher than in deep waters, and the abundance of microplastics in aquaculture sediments was three to five times that in non-aquaculture areas. Bioaccumulation demonstrated a significant trophic magnification effect, with top predators containing much higher microplastic concentrations than plankton. The combined toxicity of microplastics and pollutants severely impacted key species, leading to a 92% decrease in Chinese shrimp populations and a significant reduction in benthic biodiversity. To address this issue, a “four-in-one” prevention and control system was proposed, encompassing source reduction, intelligent monitoring, targeted treatment, and regional collaboration, with measures including policy, technological innovation, and ecological restoration. This aims to provide scientific evidence for Bohai Sea ecological security management and offer a reference for microplastic management in globally semi-enclosed seas. Full article

(This article belongs to the Special Issue Emerging Techniques in Toxicology for Environmental Health and Food Safety)

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13 pages, 1299 KiB

Open AccessArticle

Dietary Exposure to Food Contaminants of Pregnant Women in Northern Spain and Possible Effects on Fetal Anthropometric Parameters

by Daniel Hinojosa-Nogueira, José Ramón Bahamonde, Marta Aguilera-Nieto, Beatriz Navajas-Porras, Verónica González-Vigil, José Ángel Rufián-Henares and Silvia Pastoriza de la Cueva

Toxics 2025, 13(5), 399; https://doi.org/10.3390/toxics13050399 - 16 May 2025

Abstract

A considerable number of organizations are working to improve food safety, with particular attention to vulnerable groups such as pregnant women due to the important influence of diet on fetal development. The aim of this study was to evaluate exposure to 11 food [...] Read more.

A considerable number of organizations are working to improve food safety, with particular attention to vulnerable groups such as pregnant women due to the important influence of diet on fetal development. The aim of this study was to evaluate exposure to 11 food processing contaminants and their effects on maternal and fetal health. Online questionnaires during the first and third trimesters were used to analyze the intake and exposure to different food contaminants, estimated from the contaminants food database “CONT11”, in 84 pregnant women in Oviedo (Spain) and their influence on newborn anthropometric data. Exposure to certain contaminants, such as acrylamide or total polycyclic aromatic hydrocarbons, was found to have a significant impact on maternal and fetal health, particularly in relation to birth weight or head circumference. During the third trimester, pregnant women reported dietary improvement and reduced exposure to dietary contaminants. Identifying the foods and food groups that contribute most to exposure and the potential for health professionals will facilitate the development of basic exposure reduction strategies. This study is one of the few to assess the exposure of pregnant women to a wide range of contaminants and their impact on fetal health, providing a baseline for future research. Full article

(This article belongs to the Special Issue Health Risk Evaluation of Hazardous Substances in Food)

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30 pages, 6198 KiB

Open AccessArticle

Physicochemical and Toxicological Properties of Particles Emitted from Scalmalloy During the LPBF Process

by Nikoletta Sargioti, Leonidas Karavias, Leonidas Gargalis, Anna Karatza, Elias P. Koumoulos and Evangelia K. Karaxi

Toxics 2025, 13(5), 398; https://doi.org/10.3390/toxics13050398 - 15 May 2025

Abstract

This study investigates the physicochemical and toxicological properties of Scalmalloy powder emissions generated during Laser Powder Bed Fusion (LPBF), focusing on the impact of particle morphology, oxidation, and size distribution on biological responses. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analyses [...] Read more.

This study investigates the physicochemical and toxicological properties of Scalmalloy powder emissions generated during Laser Powder Bed Fusion (LPBF), focusing on the impact of particle morphology, oxidation, and size distribution on biological responses. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analyses revealed significant variations in particle characteristics, with the highest oxidation levels and irregular morphologies observed in exhaust-derived powders. In vitro cytotoxicity evaluations using A549 lung epithelial cells showed significant reductions in cell viability (~60 to 69%) and increased oxidative stress (p < 0.05) upon exposure to virgin sieved (<20 µm) and exhaust powder samples. Conversely, samples from the build plate, overflow, and dispenser exhibited high cell viability (>85%). Indirect exposure through media incubation resulted in minimal cytotoxicity, suggesting that metal dissolution plays a limited role in toxicity under the studied conditions. The findings highlight the influence of particle morphology and oxidation on cytotoxic responses and underscore the need for controlled powder handling to mitigate occupational exposure risks in LPBF environments. Full article

(This article belongs to the Section Metals and Radioactive Substances)

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15 pages, 4469 KiB

Open AccessArticle

Effects of Diethylstilbestrol on the Structure and Function of the Spleen in Male Golden Hamsters

by Jian Li, Ruiping Xu, Qingwei Wang, Xue Bai, Yanhua Su, Yaoxing Chen and Jing Cao

Toxics 2025, 13(5), 397; https://doi.org/10.3390/toxics13050397 - 15 May 2025

Abstract

With industrial development, endocrine-disrupting chemicals have continued to accumulate in the environment, attracting growing attention due to their potential effects on biological health. The reproductive toxicity of diethylstilbestrol (DES), a synthetic estrogen widely present in the environment, is widely documented; however, studies on [...] Read more.

With industrial development, endocrine-disrupting chemicals have continued to accumulate in the environment, attracting growing attention due to their potential effects on biological health. The reproductive toxicity of diethylstilbestrol (DES), a synthetic estrogen widely present in the environment, is widely documented; however, studies on its effects on the immune system remain limited. In this study, adult male golden hamsters were subcutaneously administered varying doses of DES (0, 0.01, 0.1, and 1.0 mg/kg) for seven consecutive days to assess its immunomodulatory impact on peripheral blood and the spleen. We found that the DES treatment significantly reduced spleen index, white pulp area, and splenic lymphocyte proliferation while increasing caspase-3-positive apoptotic cells and inducible nitric oxide synthase expression. In peripheral blood, DES induced a dose-dependent suppression of lymphocyte proliferation, with lipopolysaccharide- and concanavalin A-stimulated proliferation reduced by 47.68–71.76% and 44.23–72.7%, respectively. Concurrently, DES significantly downregulated the pro-inflammatory cytokines IL-2 and IFN-γ (p < 0.01) while upregulating the anti-inflammatory cytokines IL-4 and IL-10 (p < 0.01). Furthermore, DES treatment impaired antioxidant defenses, decreasing the activity of superoxide dismutase, glutathione peroxidase, and catalase while elevating malondialdehyde levels. Notably, DES led to the upregulation of G protein-coupled estrogen receptor and estrogen receptor α at both transcriptional and protein levels, whereas estrogen receptor β mRNA expression increased despite a decline in protein levels. This study provides critical experimental evidence elucidating the immunoregulatory effects of endocrine-disrupting environmental estrogens. Full article

(This article belongs to the Special Issue Toxicity and Molecular Mechanisms of Environmental Contaminants on Animals)

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30 pages, 5318 KiB

Open AccessReview

Progress of Ship Exhaust Emissions in China’s Lijiang River: Current Status and Aftertreatment Technologies

by Pengyu Liu, Bensen Xian, Mei Wang, Yong Xiao, Xiaobin Zhou, Dandan Xu, Yanan Zhang, Huili Liu and Shaoyuan Bai

Toxics 2025, 13(5), 396; https://doi.org/10.3390/toxics13050396 - 15 May 2025

Abstract

Exhaust emissions from ships are significant threats to the environment and human health, necessitating effective control measures and treatment technologies. In response to the increasing stringency of emission regulations set by the International Maritime Organization (IMO) and national governments, the shipping industry must [...] Read more.

Exhaust emissions from ships are significant threats to the environment and human health, necessitating effective control measures and treatment technologies. In response to the increasing stringency of emission regulations set by the International Maritime Organization (IMO) and national governments, the shipping industry must adopt advanced techniques to mitigate these emissions. The study focuses on the current status of exhaust pollution prevention and control on the Lijiang River and describes the latest progress in ship emission management. It summarizes the sources and hazards of nitrogen oxides (NO_X), sulfur oxides (SO_X), and particulate matter (PM) emitted from ships. The study introduces and compares several exhaust treatment key technologies for desulfurization, denitrification, and integrated desulfurization and denitrification to emphasize their principles, processes, and characteristics. It also demonstrates the future prospects for controlling exhaust gas pollution on inland ships and advocates for the development of integrated technologies that are efficient, space-saving, and cost-effective. The research aims to provide a valuable reference for inland ship exhaust pollution prevention and control. Full article

(This article belongs to the Section Air Pollution and Health)

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14 pages, 3665 KiB

Open AccessArticle

Toxicity Response and Swimming Speed Regularity in Daphnia magna After Short-Term Exposure to Diuron

by Feihu Qin, Nanjing Zhao, Gaofang Yin, Yunfei Luo and Tingting Gan

Toxics 2025, 13(5), 395; https://doi.org/10.3390/toxics13050395 - 15 May 2025

Abstract

The agricultural production process contributes to the global issue of pesticide pollution. Based on the static toxicity test of diuron (DCMU) on Daphnia magna (D. magna) for EC₅₀-48 h, a concentration range of 0.2 to 1 mg/L was set [...] Read more.

The agricultural production process contributes to the global issue of pesticide pollution. Based on the static toxicity test of diuron (DCMU) on Daphnia magna (D. magna) for EC₅₀-48 h, a concentration range of 0.2 to 1 mg/L was set as sublethal concentrations, while lethal concentrations were set at 2 mg/L and 4 mg/L. This study analyzes the toxic response patterns of the swimming behavior indicators of D. magna exposed to different concentrations of DCMU. The results showed that the average speed (V) of D. magna decreased step by step with exposure time, regardless of exposure to sublethal concentration or lethal concentration. However, during the same short-term exposure period, the V of D. magna at lethal concentration was higher than that at sublethal concentration, which indicates that the swimming behavior of D. magna exposed to DCMU may be stimulated and accelerated. Compared to the control group, there is a statistically significant difference in the V of D. magna after short-term exposure, especially showing an extremely significant difference after 5 min of exposure. Evidently, compared to the traditional 48 h static toxicity testing method, the swimming behavior indicators of D. magna show a more sensitive response to DCMU after 5 min of exposure, making it more suitable for rapid toxicity detection. By expanding the range of exposure concentrations, it was found that the V indicator of D. magna responded significantly to a DCMU concentration of 0.05 mg/L after only 5 min of exposure, and a high degree of correlation was observed between the indicator and the exposure concentration. Through nonlinear fitting, the relationship between V and the dose–effect of DCMU toxicity presents an S-shaped curve, with R² > 0.9. Consequently, it becomes possible to study the dose–effect relationship between the changes in the swimming behavior indicators of D. magna and the stress concentration based on this theory. This further establishes a foundation for the development of comprehensive aquatic toxicity rapid detection technology based on the toxic response of swimming behavior indicators. Full article

(This article belongs to the Special Issue Monitoring and Risk Assessment of Emerging Chemical Contaminants in the Aquatic Environment)

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21 pages, 8942 KiB

Open AccessArticle

Biogeochemical Mechanisms of HCO₃–Ca Water and NO₃⁻ Pollution in a Typical Piedmont Agricultural Area: Insights from Nitrification and Carbonate Weathering

by Li Xu, Bo Xin, Wei Liu, Haoyang Liu, Guoli Yang and Guizhen Hao

Toxics 2025, 13(5), 394; https://doi.org/10.3390/toxics13050394 - 15 May 2025

Abstract

Water hardening and NO₃⁻ pollution have affected water quality globally. These environmental problems threaten social sustainability and human health, especially in piedmont agricultural areas. The aim of this study is to determine the biogeochemical mechanisms of HCO³–Ca water and [...] Read more.

Water hardening and NO₃⁻ pollution have affected water quality globally. These environmental problems threaten social sustainability and human health, especially in piedmont agricultural areas. The aim of this study is to determine the biogeochemical mechanisms of HCO³–Ca water and NO₃⁻ pollution in a typical piedmont agricultural area (Qingshui River, Zhangjiakou, China). Here, an extensive biogeochemical investigation was conducted in a typical piedmont agricultural area (Qingshui River, China) using multiple hydrochemical, isotopic (δ²H-H₂O, δ¹⁸O-H₂O and δ¹³C-DIC) and molecular-biological proxies in combination with a forward model. In the region upstream of the Qingshui River, riverine hydrochemistry was dominated by HCO₃–Ca water, with only NO₃⁻ concentrations (3.08–52.8 mg/L) exceeding the acceptable limit (10 mg/L as N) for drinking water quality. The riverine hydrochemistry responsible for the formation of HCO₃–Ca water was mainly driven by carbonate dissolution, with a contribution rate of 49.8 ± 3.96%. Riverine NO₃⁻ was mainly derived from agricultural NH₄⁺ emissions rather than NO₃⁻ emissions, originating from sources such as manure, domestic sewage, soil nitrogen and NH₄⁺-synthetic fertilizer. Under the rapid hydrodynamic conditions and aerobic water environment of the piedmont area, NH₄⁺-containing pollutants were converted to HNO₃ by nitrifying bacteria (e.g., Flavobacterium and Fluviimonas). Carbonate (especially calcite) was preferentially and rapidly dissolved by the produced HNO₃, which was attributed to the strong acidity of HNO₃. Therefore, higher levels of Ca²⁺, Mg²⁺, HCO₃⁻ and NO₃⁻ were simultaneously released into river water, causing riverine HCO₃–Ca water and NO₃⁻ pollution in the A-RW. In contrast, these biogeochemical mechanisms did not occur significantly in the downstream region of the river due to the cement-hardened river channels and strict discharge management. These findings highlight the influence of agricultural HNO₃ on HCO₃–Ca water and NO₃⁻ pollution in the Qingshui River and further improve the understanding of riverine hydrochemical evolution and water pollution in piedmont agricultural areas. Full article

(This article belongs to the Special Issue Emerging Techniques in Monitoring and Mitigating Health Risks of Potentially Toxic Elements (PTEs) in the Environment)

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18 pages, 4165 KiB

Open AccessArticle

Using Geochemistry, Stable Isotopes and Statistical Tools to Estimate the Sources and Transformation of Nitrate in Groundwater in Jinan Spring Catchment, China

by Kairan Wang, Mingyuan Fan, Zhen Wu, Xin Zhang, Hongbo Wang, Xuequn Chen and Mingsen Wang

Toxics 2025, 13(5), 393; https://doi.org/10.3390/toxics13050393 - 14 May 2025

Abstract

Nitrate (NO₃⁻) pollution resulting from anthropogenic activities represents one of the most prevalent environmental issues in karst spring catchments of northern China. In June 2021, a comprehensive study was conducted in the Jinan Spring Catchment (JSC), where 30 groundwater and [...] Read more.

Nitrate (NO₃⁻) pollution resulting from anthropogenic activities represents one of the most prevalent environmental issues in karst spring catchments of northern China. In June 2021, a comprehensive study was conducted in the Jinan Spring Catchment (JSC), where 30 groundwater and surface water samples were collected. The sources and spatial distribution of nitrate pollution were systematically investigated through hydrochemical analysis combined with dual-isotope tracing techniques (δ¹⁵N_NO3 and δ¹⁸O_NO3). Analytical results revealed that the predominant anion and cation sequences were HCO₃⁻ > SO₄²⁻ > Cl⁻ > NO₃⁻ and Ca²⁺ > Na⁺ > Mg²⁺ > K⁺, respectively, with HCO₃·SO₄-Ca identified as the primary hydrochemical type. Notably, the average NO₃⁻ concentration in groundwater (46.62 mg/L) significantly exceeded that in surface water (4.96 mg/L). Among the water samples, 11 locations exhibited substantial nitrate pollution, demonstrating an exceedance rate of 42%. Particularly, the NO₃⁻-N concentrations in both the upstream recharge area and downstream drainage area were markedly higher than those in the runoff area. The spatial distribution of NO₃⁻ concentrations was primarily influenced by mixing processes, with no significant evidence of denitrification observed. The isotopic compositions ranged from −1.42‰ to 12.79‰ for δ¹⁵N_NO3 and 0.50‰ to 15.63‰ for δ¹⁸O_NO3. Bayesian isotope mixing model (MixSIAR) analysis indicated that domestic sewage and manure constituted the principal nitrate sources, contributing 37.1% and 56.9% to groundwater and surface water, respectively. Secondary sources included soil organic nitrogen, rainfall and fertilizer NH₄⁺, and chemical fertilizers, while atmospheric deposition showed the lowest contribution rate. Additionally, potential mixing of soil organic nitrogen with chemical fertilizer was identified. Full article

(This article belongs to the Special Issue Emerging Techniques in Monitoring and Mitigating Health Risks of Potentially Toxic Elements (PTEs) in the Environment)

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24 pages, 6323 KiB

Open AccessArticle

Estimating PM_2.5 Exposures and Cardiovascular Disease Risks in the Yangtze River Delta Region Using a Spatiotemporal Convolutional Approach to Fill Gaps in Satellite Data

by Muhammad Jawad Hussain, Myeongsu Seong, Behjat Shahid and Heming Bai

Toxics 2025, 13(5), 392; https://doi.org/10.3390/toxics13050392 - 14 May 2025

Abstract

Accurate estimation of ambient PM_2.5 concentrations is crucial for assessing air quality and health risks, particularly in regions with limited ground-based monitoring. Satellite-retrieved data products, such as top-of-atmosphere reflectance (TOAR) and aerosol optical depth (AOD), are widely used for PM_2.5 estimation. [...] Read more.

Accurate estimation of ambient PM_2.5 concentrations is crucial for assessing air quality and health risks, particularly in regions with limited ground-based monitoring. Satellite-retrieved data products, such as top-of-atmosphere reflectance (TOAR) and aerosol optical depth (AOD), are widely used for PM_2.5 estimation. However, complex atmospheric conditions cause retrieval gaps in TOAR and AOD products, limiting their reliability. This study introduced a spatiotemporal convolutional approach to fill sampling gaps in TOAR and AOD data from the Himawari-8 geostationary satellite over the Yangtze River Delta (YRD) in 2016. Four machine-learning models (random forest, extreme gradient boosting, gradient boosting, and support vector regression) were used to estimate hourly PM_2.5 concentrations by integrating gap-filled and original TOAR and AOD data with meteorological variables. The random forest model trained on gap-filled TOAR data yielded the highest predictive accuracy (R² = 0.75, RMSE = 18.30 μg m⁻³). Significant seasonal variations in PM_2.5 estimates were found, with TOAR-based models outperforming AOD-based models. Furthermore, we observed that a substantial portion of the YRD population in non-attainment areas is at risk of cardiovascular disease due to chronic PM_2.5 exposure. This study suggests that TOAR-based models offer more reliable PM_2.5 estimates, enhancing air-quality assessments and public health-risk evaluations. Full article

(This article belongs to the Special Issue The Evolution of Atmospheric Composition and Its Impact on Human Health and Ecosystem)

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20 pages, 15011 KiB

Open AccessArticle

Glacial Waters Under Threat: Risk Assessment and Source Identification of Polychlorinated Biphenyls in Meili Snow Mountains, Southeastern Tibetan Plateau

by Huawei Zhang, Yan Yao, Xinyu Wen, Rui Zhang and Rui Liu

Toxics 2025, 13(5), 391; https://doi.org/10.3390/toxics13050391 - 13 May 2025

Abstract

Polychlorinated biphenyls (PCBs) are classified as persistent organic pollutants (POPs) due to their potential threat to both ecosystems and human health. The Tibetan Plateau (TP), characterized by its low temperatures, pristine ecological conditions, and remoteness from anthropogenic influences, serves as the investigation region. [...] Read more.

Polychlorinated biphenyls (PCBs) are classified as persistent organic pollutants (POPs) due to their potential threat to both ecosystems and human health. The Tibetan Plateau (TP), characterized by its low temperatures, pristine ecological conditions, and remoteness from anthropogenic influences, serves as the investigation region. This study analyzed water samples from the temperature glacial watershed and employed the risk assessment method established by the United States Environmental Protection Agency (US EPA) to assess both carcinogenic and non-carcinogenic risks of PCBs in five age groups. The total concentrations of PCBs (∑₃PCBs) varied from 738 to 1914 ng/L, with a mean value of 1058 ng/L, which was comparable to or exceeded levels reported in the surface water around the TP. Notably, the riverine sites located near the villages and towns exhibited the highest pollution levels. Our analyses indicated that glacier melting, long-range atmospheric transport (LRAT), reductive dechlorination processes, and various anthropogenic activities might be potential sources of PCB emission in the Meili Snow Mountains. According to the established national and international water quality standards, as well as toxic equivalency concentrations (TEQs) for dioxin-like PCBs (DL PCBs), the PCB concentrations detected in this study could result in serious biological damage and adverse ecological toxicological effects. However, the PCBs in all samples posed a negligible cancer risk to five age groups, and a non-carcinogenic risk to adults. These findings contribute valuable insights into the risks and sources of PCBs and may serve as a foundational reference for subsequent study of these compounds in the Meili Snow Mountains area of the southeastern TP. Full article

(This article belongs to the Section Exposome Analysis and Risk Assessment)

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18 pages, 845 KiB

Open AccessReview

What Do We Know About Staphylococcus aureus and Oxidative Stress? Resistance, Virulence, New Targets, and Therapeutic Alternatives

by Mírian Letícia Carmo Bastos, Gleison Gonçalves Ferreira, Isis de Oliveira Kosmiscky, Ieda Maria Louzada Guedes, José Augusto Pereira Carneiro Muniz, Liliane Almeida Carneiro, Ísis Lins de Carvalho Peralta, Marcia Nazaré Miranda Bahia, Cintya de Oliveira Souza and Maria Fâni Dolabela

Toxics 2025, 13(5), 390; https://doi.org/10.3390/toxics13050390 - 13 May 2025

Abstract

Staphylococcus aureus is associated with human infections, being a resistant bacterium involved in serious infections, and its virulence and resistance are linked to oxidative stress. In this study, we review the role of oxidative stress in the pathogenesis of this bacterium and its [...] Read more.

Staphylococcus aureus is associated with human infections, being a resistant bacterium involved in serious infections, and its virulence and resistance are linked to oxidative stress. In this study, we review the role of oxidative stress in the pathogenesis of this bacterium and its influence on immune system evasion, antibiotic resistance, and pharmacological targeting. S. aureus infection generates an intense inflammatory response in the host, evidenced by the activation of pro-inflammatory pathways, the exacerbated production of reactive oxygen species (ROS), and cellular oxidative stress. However, the bacterium develops protective mechanisms against damage, including the production of endogenous antioxidants, the formation of biofilms, and the regulation of redox metabolism, favoring pathogenicity and drug resistance. Resistance seems to be related to alterations in redox metabolism, which influences the sensitization of the immune system. Modulation of the redox response has emerged as a promising approach for developing new antibiotics and formulating more effective combination therapies to combat resistant infections. Natural compounds, including flavonoids, terpenes, and quinones, have demonstrated antibacterial properties by inducing oxidative stress in S. aureus. In summary, the involvement of oxidative stress is complex, with an increase in ROS in the infection and a reduction in immune system evasion and resistance, which could be an interesting therapeutic target. Full article

(This article belongs to the Section Drugs Toxicity)

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13 pages, 2674 KiB

Open AccessArticle

Biochar Influences the Transformation and Translocation of Antimony in the Rhizosphere–Rice System

by Qiuxiang Huang, Fande Meng, Wenzhe Chen, Yongbing Cai and Enzong Xiao

Toxics 2025, 13(5), 389; https://doi.org/10.3390/toxics13050389 - 13 May 2025

Abstract

The rhizosphere is a crucial interface that connects the soil and the roots of plants, playing a critical role in regulating soil biochemical functions and processes. Biochar, an increasingly common soil amendment, can directly or indirectly affect the redistribution behavior of heavy metal(loid)s. [...] Read more.

The rhizosphere is a crucial interface that connects the soil and the roots of plants, playing a critical role in regulating soil biochemical functions and processes. Biochar, an increasingly common soil amendment, can directly or indirectly affect the redistribution behavior of heavy metal(loid)s. Our study used a rice pot experiment to investigate the redistribution behavior of antimony (Sb) in the rhizosphere–rice system during the four key rice growth stages and analyze the effects of biochar (BC). Biochar increased pH, soil organic matter (SOM), and dissolved organic carbon (DOC) but decreased Eh, affecting Sb redistribution in the rhizosphere–rice system. The Sb fractions were altered with rice growth and the addition of BC. For example, bioavailable Sb increased by 1.57–32.97% in the presence of BC across all rice growth stages. Biochar reduced the BCF and TFR-S of Sb but elevated the TFS-G, indicating that biochar reduced Sb migration from the soil to the rice roots and the rice roots to shoots but increased Sb migration from rice shoots to grains. This study highlights the potential use of biochar as a reclamation agent in remediating Sb-contaminated soils and protecting human health from Sb through the food chain. Full article

(This article belongs to the Special Issue Novel Remediation Strategies for Soil Pollution)

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