Toxics

18 pages, 1619 KiB

Open AccessArticle

The Metallothionein System in Tetrahymena thermophila Is Iron-Inducible

by Davide Gualandris, Davide Rotondo, Candida Lorusso, Antonietta La Terza, Antonio Calisi and Francesco Dondero

Toxics 2024, 12(10), 725; https://doi.org/10.3390/toxics12100725 - 8 Oct 2024

Abstract

Metallothioneins are multifunctional proteins implicated in various cellular processes. They have been used as biomarkers of heavy metal exposure and contamination due to their intrinsic ability to bind heavy metals and their transcriptional response to both physiological and noxious metal ions such as [...] Read more.

Metallothioneins are multifunctional proteins implicated in various cellular processes. They have been used as biomarkers of heavy metal exposure and contamination due to their intrinsic ability to bind heavy metals and their transcriptional response to both physiological and noxious metal ions such as cadmium (Cd) and mercury (Hg). In this study, we aimed to clarify the role of iron and reactive oxygen species (ROSs) in the induction of the metallothionein system (Mtt) in the ciliate protozoan Tetrahymena thermophila. We investigated the relative mRNA abundances of the metallothionein genes Mtt1, Mtt2/4, and Mtt5, revealing for the first time their responsiveness to iron exposure. Furthermore, by using inhibitors of superoxide dismutase (SOD) and catalase (CAT), alone or in combination with iron, we highlighted the roles of superoxide ion and endogenous hydrogen peroxide, as well as the complex interplay between the metal and ROSs. These results enhance our understanding of the metallothionein system in ciliates and suggest that ROSs may be a primary evolutionary driver for the selection of these proteins in nature. Full article

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

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13 pages, 2739 KiB

Open AccessArticle

ZnO Nanoparticles-Induced MRI Alterations to the Rat Olfactory Epithelium and Olfactory Bulb after Intranasal Instillation

by Lifeng Gao, Yuguang Meng, Xiaowen Luo, Jiangyuan Chen and Xuxia Wang

Toxics 2024, 12(10), 724; https://doi.org/10.3390/toxics12100724 - 5 Oct 2024

Abstract

Since zinc oxide (ZnO) nanoparticles (NPs) have been widely applied, the nano community and the general public have paid great attention to the toxicity of ZnO NPs. We detected 20-nm ZnO NPs biotoxicity following nasal exposure utilizing the non-invasive and real-time magnetic resonance [...] Read more.

Since zinc oxide (ZnO) nanoparticles (NPs) have been widely applied, the nano community and the general public have paid great attention to the toxicity of ZnO NPs. We detected 20-nm ZnO NPs biotoxicity following nasal exposure utilizing the non-invasive and real-time magnetic resonance imaging (MRI) technique. MR images were scanned in the rat olfactory epithelium (OE) and olfactory bulb (OB) on a 4.7 T scanner following the treatment (as early as 1 day and up to 21 days after), and the histological changes were evaluated. The influence of the size of the ZnO NPs and chemical components was also investigated. Our study revealed that 20-nm ZnO NPs induced obvious structural disruption and inflammation in the OE and OB at the acute stage. The results suggest that the real-time and non-invasive advantages of MRI allow it to observe and assess, directly and dynamically, the potential toxicity of long-term exposure to ZnO NPs in the olfactory system. These findings indicate the size-dependent toxicity of ZnO NPs with respect to the olfactory bulb. Further study is needed to reveal the mechanism behind ZnO NPs’ toxicity. Full article

(This article belongs to the Special Issue Health Effects of Exposure to Environmental Pollutants)

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12 pages, 4531 KiB

Open AccessArticle

Adverse Outcomes Following Exposure to Perfluorooctanesulfonamide (PFOSA) in Larval Zebrafish (Danio rerio): A Neurotoxic and Behavioral Perspective

by Nikita David, Emma Ivantsova, Isaac Konig, Cole D. English, Lev Avidan, Mark Kreychman, Mario L. Rivera, Camilo Escobar, Eliana Maira Agostini Valle, Amany Sultan and Christopher J. Martyniuk

Toxics 2024, 12(10), 723; https://doi.org/10.3390/toxics12100723 - 4 Oct 2024

Abstract

Toxicity mechanisms of per- and polyfluoroalkyl substances (PFASs), a chemical class present in diverse ecosystems, as well as many of their precursors, have been increasingly characterized in aquatic species. Perfluorooctanesulfonamide (PFOSA, C₈H₂F₁₇NO₂S) is a common [...] Read more.

Toxicity mechanisms of per- and polyfluoroalkyl substances (PFASs), a chemical class present in diverse ecosystems, as well as many of their precursors, have been increasingly characterized in aquatic species. Perfluorooctanesulfonamide (PFOSA, C₈H₂F₁₇NO₂S) is a common precursor of perfluorooctane sulfonic acid (PFOS), a long-chain PFAS. Here, we assessed sub-lethal endpoints related to development, oxidative stress, transcript levels, and distance moved in zebrafish embryos and larvae following continuous exposure to PFOSA beginning at 6 h post-fertilization (hpf). PFOSA decreased survival in fish treated with 1 µg/L PFOSA; however, the effect was modest relative to the controls (difference of 10%). Exposure up to 10 µg/L PFOSA did not affect hatch rate, nor did it induce ROS in 7-day-old larvae fish. The activity of larval fish treated with 100 µg/L PFOSA was reduced relative to the solvent control. Transcripts related to oxidative stress response and apoptosis were measured and BCL2-associated X, apoptosis regulator (bax), cytochrome c, somatic (cycs), catalase (cat), superoxide dismutase 2 (sod2) were induced with high concentrations of PFOSA. Genes related to neurotoxicity were also measured and transcript levels of acetylcholinesterase (ache), elav-like RNA binding protein 3 (elavl3), growth-associated protein 43 (gap43), synapsin II (syn2a), and tubulin 3 (tubb3) were all increased in larval fish with higher PFOSA exposure. These data improve our understanding of the potential sub-lethal toxicity of PFOSA in fish species. Full article

(This article belongs to the Special Issue Impact of Per- and Polyfluoroalkyl Substances (PFAS) on Aquatic Animals: Immunotoxicity, Endocrine Disruption, and Beyond)

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14 pages, 3791 KiB

Open AccessArticle

Chromium Selectively Accumulates in the Rat Hippocampus after 90 Days of Exposure to Cr(VI) in Drinking Water and Induces Age- and Sex-Dependent Metal Dyshomeostasis

by Samuel T. Vielee, William J. Buchanan, Spencer H. Roof, Rehan Kahloon, Elizabeth Evans, Jessica Isibor, Maitri Patel, Idoia Meaza, Haiyan Lu, Aggie R. Williams, J. Calvin Kouokam, Sandra S. Wise, Luping Guo, Rachel M. Wise, Jamie L. Wise, Lu Cai, Jun Cai and John P. Wise, Jr.

Toxics 2024, 12(10), 722; https://doi.org/10.3390/toxics12100722 - 3 Oct 2024

Abstract

Hexavalent chromium (Cr[VI]) is a widespread environmental pollutant in air and water that is primarily attributed to industrial pollution. The current maximum contaminant levels (MCLs) for drinking water from the World Health Organization and the U.S. Environmental Protection Agency (0.05 and 0.1 mg/L, [...] Read more.

Hexavalent chromium (Cr[VI]) is a widespread environmental pollutant in air and water that is primarily attributed to industrial pollution. The current maximum contaminant levels (MCLs) for drinking water from the World Health Organization and the U.S. Environmental Protection Agency (0.05 and 0.1 mg/L, respectively) were set based on contact dermatitis and warrant further toxicological investigation. While Cr(VI) is neurotoxic and accumulates in the brain, most animal studies only report whole-brain Cr, leaving large knowledge gaps. Few studies consider differences between ages or sexes, and fewer consider essential metal dyshomeostasis. We sought to investigate where Cr accumulates in the brain, considering sex and age differences, following a 90-day drinking water exposure to current MCLs. Here, we report Cr levels in six brain regions of rats exposed to drinking water Cr(VI). We observed Cr only accumulated in the hippocampus, and only in older females. We further assessed changes to essential metals in the hippocampus, observing opposite effects across sexes and between young rats compared to older rats. In sum, our data indicate drinking water Cr(VI) selectively targeted the hippocampus, with geriatric females accumulating the most Cr, and induced significant essential metal dyshomeostasis even in tissues lacking evident Cr accumulation. Full article

(This article belongs to the Special Issue Advanced Techniques for Detection and Investigation in Heavy Metals Toxicology)

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22 pages, 4499 KiB

Open AccessReview

The Application of Nano Zero-Valent Iron in Synergy with White Rot Fungi in Environmental Pollution Control

by Guoming Zeng, Zilong Ma, Rui Zhang, Yu He, Xuanhao Fan, Xiaoling Lei, Yong Xiao, Maolan Zhang and Da Sun

Toxics 2024, 12(10), 721; https://doi.org/10.3390/toxics12100721 - 2 Oct 2024

Abstract

Developing efficient and sustainable pollution control technologies has become a research priority in the context of escalating global environmental pollution. Nano zero-valent iron (nZVI), with its high specific surface area and strong reducing power, demonstrates remarkable performance in pollutant removal. Still, its application [...] Read more.

Developing efficient and sustainable pollution control technologies has become a research priority in the context of escalating global environmental pollution. Nano zero-valent iron (nZVI), with its high specific surface area and strong reducing power, demonstrates remarkable performance in pollutant removal. Still, its application is limited by issues such as oxidation, passivation, and particle aggregation. White rot fungi (WRF) possess a unique enzyme system that enables them to degrade a wide range of pollutants effectively, yet they face challenges such as long degradation cycles and low degradation efficiency. Despite the significant role of nZVI in pollutant remediation, most contaminated sites still rely on microbial remediation as a concurrent or ultimate treatment method to achieve remediation goals. The synergistic combination of nZVI and WRF can leverage their respective advantages, thereby enhancing pollution control efficiency. This paper reviews the mechanisms, advantages, and disadvantages of nZVI and WRF in pollution control, lists application examples, and discusses their synergistic application in pollution control, highlighting their potential in pollutant remediation and providing new insights for combined pollutant treatment. However, research on the combined use of nZVI and WRF for pollutant remediation is still relatively scarce, necessitating a deeper understanding of their synergistic potential and further exploration of their cooperative interactions. Full article

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

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18 pages, 4551 KiB

Open AccessArticle

A Chemometric Exploration of Potential Chemical Markers and an Assessment of Associated Risks in Relation to the Botanical Source of Fruit Spirits

by Branislava Srdjenović Čonić, Nebojša Kladar, Dejan Kusonić, Katarina Bijelić and Ljilja Torović

Toxics 2024, 12(10), 720; https://doi.org/10.3390/toxics12100720 - 2 Oct 2024

Abstract

Chemometric evaluation of potentially harmful volatile compound and toxic metal(loid) distribution patterns in fruit spirits relating to distinct fruit classes most commonly used in spirit production highlighted the potential of several volatiles as candidates for differentiation markers while dismissing toxic metal(loid)s. Pome fruit [...] Read more.

Chemometric evaluation of potentially harmful volatile compound and toxic metal(loid) distribution patterns in fruit spirits relating to distinct fruit classes most commonly used in spirit production highlighted the potential of several volatiles as candidates for differentiation markers while dismissing toxic metal(loid)s. Pome fruit and grape pomace spirits were mostly characterized by a lower abundance of n-propanol, methanol, ethyl acetate and acetaldehyde, while stone fruit spirits contained lower amounts of isoamyl alcohol and isobutanol. Chemometric analysis of the fruit spirit composition of aromatics identified additional potential markers characteristic for certain fruits—benzoic acid ethyl ester, benzyl alcohol, benzaldehyde, butanoic acid 3-methyl-ethyl ester, butanoic acid 2-methyl-ethyl ester and furfural. This study explored the variability in the risk potential of the investigated spirits, considering that some chemicals known to be detected in spirits are potent health hazards. Ethyl carbamate in combination with acetaldehyde showed a higher potential risk in stone fruit spirits, methanol in stone and pome fruit spirits and acetaldehyde in grape pomace spirits. It is of great interest to evaluate to what extent consumers’ preference for spirits of distinct fruit types affects health risks. Consumers of stone fruit spirits are potentially at higher risk than those consuming pome fruit or grape pomace spirits. Full article

(This article belongs to the Special Issue New Approach Methodologies for Agrochemicals and Food Toxicology)

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24 pages, 11718 KiB

Open AccessArticle

Selenomethionine and Allicin Synergistically Mitigate Intestinal Oxidative Injury by Activating the Nrf2 Pathway

by Yongshi Liu, Xi Lv, Heling Yuan, Xiaoming Wang, Jinhu Huang and Liping Wang

Toxics 2024, 12(10), 719; https://doi.org/10.3390/toxics12100719 - 30 Sep 2024

Abstract

Oxidative stress frequently contributes to intestinal barrier injury in animals and humans. It was reported that both Selenomethionine (SeMet) and allicin exhibit protective effects against a range of diseases caused by oxidative stress. This study aimed to investigate the synergistic antioxidant effects and [...] Read more.

Oxidative stress frequently contributes to intestinal barrier injury in animals and humans. It was reported that both Selenomethionine (SeMet) and allicin exhibit protective effects against a range of diseases caused by oxidative stress. This study aimed to investigate the synergistic antioxidant effects and underlying mechanisms of SeMet and allicin on a H₂O₂-induced intestinal barrier injury model using IPEC-J2 cells and mice. The results showed that H₂O₂ induced severe oxidative stress, including a decrease in cell viability, antioxidant level, migration capacity, and cell integrity. SeMet and allicin exhibited significant synergistic anti-oxidative effects on intestinal epithelial cells. The combined use of SeMet and allicin increased SOD activity, GSH content, and GSH/GSSG ratio while decreasing MDA, NO, and ROS content levels. Furthermore, we found that SeMet and allicin synergistically activated the nuclear factor erythroid-related factor 2 (Nrf2)-NAD(P)H dehydrogenase [quinone] 1 (NQO1) signaling pathway and down-regulated endoplasmic reticulum stress (ER stress)-related proteins. However, the synergistic antioxidative and intestinal barrier protective effects of SeMet and allicin were abolished by Nrf2 inhibitor ML385 in vitro and in vivo. In conclusion, SeMet and allicin synergistically attenuate intestinal barrier injury induced by excessively oxidative stress through the activation of the Nrf2 signaling pathway and inhibition ER stress. These findings support that the combined use of SeMet and allicin could enhance antioxidative properties and alleviate intestinal injury in further clinical practice. Full article

(This article belongs to the Special Issue Exploring the Multifaceted Role of Antioxidants: From Molecular Mechanisms to Therapeutic Applications)

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16 pages, 3696 KiB

Open AccessArticle

Sodium Hypochlorite (NaClO) Disturbed Lipid Metabolism in Larval Zebrafish (Danio rerio), as Revealed by Lipidomics and Transcriptomics Analyses

by Wen Wang, Hua Yang, Xingning Xiao, Qu Chen, Wentao Lv, Lingyan Ma, Chanlin Fang, Yuanxiang Jin and Yingping Xiao

Toxics 2024, 12(10), 718; https://doi.org/10.3390/toxics12100718 - 30 Sep 2024

Abstract

Sodium hypochlorite (NaClO) has been widely utilized since the initial outbreak of coronavirus disease (COVID-19). The widespread use of NaClO means that it can directly enter aquatic ecosystems through wastewater discharge. In this study, we analyzed the expression of PPAR-γ, FAS, [...] Read more.

Sodium hypochlorite (NaClO) has been widely utilized since the initial outbreak of coronavirus disease (COVID-19). The widespread use of NaClO means that it can directly enter aquatic ecosystems through wastewater discharge. In this study, we analyzed the expression of PPAR-γ, FAS, and ACC1, which significantly increased in larval zebrafish following exposure to 300 μg/L NaClO for 7 days. Additionally, we examined the effects of high concentrations of NaClO on zebrafish through non-targeted lipidomics and transcriptomics. A total of 44 characteristic lipid molecules were identified using non-targeted lipidomics; an absolute quantitative analysis revealed that the contents of these subclasses of lipids decreased significantly following exposure to 300 μg/L NaClO for 7 days. The levels of triglyceride (TG), phosphatidylethanolamines (PE), and diglyceride (DG) were particularly affected. Transcriptomic analysis revealed that exposure to 300 μg/L NaClO could significantly disrupt global gene transcription in larval zebrafish. Interestingly, more than 700 differentially expressed genes (DEGs) were identified, primarily associated with lipid metabolism and glycometabolism pathways. Overall, our study provided new insights into the toxicological effects of chlorine-containing disinfectants in aquatic organisms. Full article

(This article belongs to the Section Novel Methods in Toxicology Research)

18 pages, 12366 KiB

Open AccessArticle

Enhanced Adsorption of Cadmium by a Covalent Organic Framework-Modified Biochar in Aqueous Solution

by Yanwei Hou, Shanna Lin, Jiajun Fan, Youchi Zhang, Guohua Jing and Chao Cai

Toxics 2024, 12(10), 717; https://doi.org/10.3390/toxics12100717 - 30 Sep 2024

Abstract

In the environmental field, the advancement of new high-efficiency heavy metal adsorption materials remains a continuous research focus. A novel composite, covalent organic framework-modified biochar (RH-COF), was fabricated via an in-situ polymerization approach in this study. The COF-modified biochar was characterized by elemental [...] Read more.

In the environmental field, the advancement of new high-efficiency heavy metal adsorption materials remains a continuous research focus. A novel composite, covalent organic framework-modified biochar (RH-COF), was fabricated via an in-situ polymerization approach in this study. The COF-modified biochar was characterized by elemental analysis, BET analysis, SEM, FT-IR, and XPS. The nitrogen and oxygen content in the modified material increased significantly from 0.96% and 15.50% to 8.88% and 22.37%, respectively, indicating the addition of a substantial number of nitrogen- and oxygen-containing functional groups to the RH-COF surface, thereby enhancing its adsorption capacity for Cd from 4.20 mg g⁻¹ to 58.62 mg g⁻¹, representing an approximately fourteen-fold increase. Both the pseudo-second-order model and the Langmuir model were suitable for describing the kinetics and isotherms of Cd²⁺ adsorption onto RH-COF. The adsorption performance of Cd²⁺ by RH-COF showed minimal sensitivity to pH values between 4.0 and 8.0, but could be slightly influenced by ionic strength. Mechanistic analysis showed that the Cd²⁺ adsorption on RH-COF was dominated by surface complexation and chelation, alongside electrostatic adsorption, surface precipitation, and Cπ–cation interactions. Overall, these findings suggest that the synthesis of COF-biochar composite may serve as a promising remediation strategy while providing scientific support for applying COF in environmental materials. Full article

(This article belongs to the Special Issue Environmental Transport and Transformation of Pollutants)

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14 pages, 634 KiB

Open AccessArticle

Impact of Skin Decontamination Wipe Solutions on the Percutaneous Absorption of Polycyclic Aromatic Hydrocarbons

by Chandler Probert, R. Bryan Ormond and Ronald E. Baynes

Toxics 2024, 12(10), 716; https://doi.org/10.3390/toxics12100716 - 30 Sep 2024

Abstract

Firefighter occupational exposures were categorized as a class 1 (known) carcinogen by the International Agency for Research on Cancer in 2022. As a result, firefighters have become heavily focused on identifying effective and easy to implement decontamination strategies to reduce their chemical exposures. [...] Read more.

Firefighter occupational exposures were categorized as a class 1 (known) carcinogen by the International Agency for Research on Cancer in 2022. As a result, firefighters have become heavily focused on identifying effective and easy to implement decontamination strategies to reduce their chemical exposures. Skin decontamination using wipes post-exposure is one decontamination strategy that every firefighter has available to them. However, firefighters have expressed concerns over the ingredients in the wipe solution increasing dermal absorption. The goal of this study was to determine if the ingredients in skin decontamination wipe solution had any enhancement effect on the dermal absorption of phenanthrene. To determine any enhancement effects, the additive solution of four skin decontamination wipe products was applied to porcine skin 15 min after chemical dosing. The absorption of phenanthrene was tested in vitro using a flow-through diffusion cell system over eight hours. The wipe solution effects on dermal absorption were determined by measuring multiple absorption characteristics including cumulative absorption (µg/cm²), absorption efficiency (% dose absorbed), lag time (minutes), flux (µg/cm²/h), diffusivity (cm²/h), and permeability (cm/h). No penetration enhancement effects were observed in any of the skin decontamination wipe solutions tested; rather, all wipe solutions decreased the absorption of phenanthrene. Slight differences in cumulative absorption among two pairings of skin decontamination wipe solutions, wipes 1 and 3 vs. wipes 2 and 4, were observed, indicating that some ingredients may impact dermal absorption. These findings show that firefighters should continue using skin decontamination wipes to reduce their dermal exposures to fireground contaminants with little concern of increasing the absorption of phenanthrene. Full article

(This article belongs to the Special Issue Firefighters’ Occupational Exposures and Health Risks)

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15 pages, 863 KiB

Open AccessReview

Overview of Methylation and Demethylation Mechanisms and Influencing Factors of Mercury in Water

by Wenyu Zhao, Runjie Gan, Bensen Xian, Tong Wu, Guoping Wu, Shixin Huang, Ronghua Wang, Zixuan Liu, Qin Zhang, Shaoyuan Bai, Mingming Fu and Yanan Zhang

Toxics 2024, 12(10), 715; https://doi.org/10.3390/toxics12100715 - 30 Sep 2024

Abstract

Mercury, particularly in its methylated form, poses a significant environmental and health risk in aquatic ecosystems. While the toxicity and bioaccumulation of mercury are well documented, there remains a critical gap in our understanding of the mechanisms governing mercury methylation and demethylation in [...] Read more.

Mercury, particularly in its methylated form, poses a significant environmental and health risk in aquatic ecosystems. While the toxicity and bioaccumulation of mercury are well documented, there remains a critical gap in our understanding of the mechanisms governing mercury methylation and demethylation in aquatic environments. This review systematically examines the complex interplay of chemical, biological, and physical factors that influence mercury speciation and transformation in natural water systems. We provide a comprehensive analysis of methylation and demethylation processes, specifically focusing on the dominant role of methanogenic bacteria. Our study highlights the crucial function of hgcAB genes in facilitating mercury methylation by anaerobic microorganisms, an area that represents a frontier in current research. By synthesizing the existing knowledge and identifying key research priorities, this review offers novel insights into the intricate dynamics of mercury cycling in aquatic ecosystems. Our findings provide a theoretical framework to inform future studies and guide pollution management strategies for mercury and its compounds in aquatic environments. Full article

(This article belongs to the Topic The Challenges and Future Trends in Anthropogenic and Natural Pollution Control Engineering)

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9 pages, 2528 KiB

Open AccessArticle

Possible Causes of Extreme Variation of Benzo[a]pyrene Acute Toxicity Test on Daphnia magna

by Zi-Yi Zheng, Yu-Ting Yang, Jing-Xuan Zhou, Zhao-Xing Peng and Hong-Gang Ni

Toxics 2024, 12(10), 714; https://doi.org/10.3390/toxics12100714 - 30 Sep 2024

Abstract

There are enormous differences in benzo[a]pyrene (BaP) acute toxicity tests on Daphnia magna, according to previous publications. The explanations of the reasons for this extreme variation are necessary. In this context, the acute toxicity tests of different experiment conditions (light/dark, culture medium, [...] Read more.

There are enormous differences in benzo[a]pyrene (BaP) acute toxicity tests on Daphnia magna, according to previous publications. The explanations of the reasons for this extreme variation are necessary. In this context, the acute toxicity tests of different experiment conditions (light/dark, culture medium, and solvent) were conducted on Daphnia magna with BaP as the toxicant of concern. Based on the experiments above, molecular dynamics (MD) simulations were employed to investigate the mechanisms of action. According to our results, the significant influence of light exposure on the acute toxicity test of BaP (p < 0.05) on D. magna was recorded. On the basis of the MD simulations, it was possible that BaP may not affect the normal operation of Superoxide Dismutase and Catalase directly, and it could be quickly transferred from the body through Glutathione S-transferase and Cytochromes P450. Therefore, when exposed to light, the oxidative stress process intensifies, causing damage to Daphnia magna. Apparently, the ecotoxicity tests based on inhibition for D. magna cannot adequately reflect the toxic effects of BaP. Full article

(This article belongs to the Section Emerging Contaminants)

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20 pages, 4197 KiB

Open AccessArticle

Removal of Lead Cations by Novel Organoclays Derived from Bentonite and Amphoteric and Nonionic Surfactants

by Maria Gertsen, Leonid Perelomov, Anna Kharkova, Marina Burachevskaya, S. Hemalatha and Yury Atroshchenko

Toxics 2024, 12(10), 713; https://doi.org/10.3390/toxics12100713 - 30 Sep 2024

Abstract

For many decades, natural and modified clay minerals have been used as adsorbents to clean up aquatic and soil ecosystems contaminated with organic and inorganic pollutants. In this study, organoclays based on bentonite and various amphoteric and nonionic surfactants were synthesized and tested [...] Read more.

For many decades, natural and modified clay minerals have been used as adsorbents to clean up aquatic and soil ecosystems contaminated with organic and inorganic pollutants. In this study, organoclays based on bentonite and various amphoteric and nonionic surfactants were synthesized and tested as effective sorbents for lead ions. The maximum values of R were obtained when describing the sorption processes using the Langmuir model, which ranged from 0.97 to 0.99. The adsorption of lead ions by these organoclays was investigated using different sorption models including the Langmuir, Freundlich, and BET. It was found that, according to the values of limiting adsorption to the Langmuir equation, the synthesized organoclays formed an increasing series: organoclay with cocamide diethanolamine < bentonite < organoclay with lauramine oxide < organoclay with sodium cocoiminodipropionate < organoclay with disodium cocoamphodiacetate < organoclay with alkyl polyglucoside. The Gibbs energy for all of the analyzed samples was calculated and found to be negative, indicating the spontaneity of the cation adsorption process in the forward direction. The maximum value of the adsorption capacity of lead cations on organoclay-based bentonite with alkyl polyglucoside was 1.49 ± 0.05 mmol/g according to the Langmuir model, and 0.523 ± 0.003 mmol/g as determined by the BET model. In the process of modifying bentonite, there was an increase in negative values of the zeta potential for organoclays compared to the initial mineral, which clearly enhanced their electrostatic interactions with the positively charged lead ions. It was hypothesized, based on the physicochemical principles, that exchange adsorption is the main mechanism for lead absorption. Based on chemical approaches, organoclays based on amphoteric surfactants absorb lead mainly through the mechanisms of electrostatic attraction, ion exchange, and complexation as well as the formation of insoluble precipitates. Organoclays based on nonionic surfactants, on the other hand, absorb lead through mechanisms of complexation (including chelation) and the formation of insoluble chemical precipitates. The comparison of isotherms from different models allows us to find the most accurate match between the model and the experimental data, and to better understand the nature of the processes involved. Full article

(This article belongs to the Special Issue Integrated Remediation Processes toward Heavy Metal-Contaminated Environment)

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21 pages, 4155 KiB

Open AccessArticle

Mitochondrial Dysfunction Plays a Relevant Role in Heart Toxicity Caused by MeHg

by Marcia Gracindo Silva, Camila Guerra Martinez, Joao Paulo Cavalcanti de Albuquerque, André Luiz Gouvêa, Monica Maria Freire, Leidiane Caroline Lauthartte, Julio Mignaco, Wanderley Rodrigues Bastos, Elisabete Cesar de Mattos, Antonio Galina and Eleonora Kurtenbach

Toxics 2024, 12(10), 712; https://doi.org/10.3390/toxics12100712 - 30 Sep 2024

Abstract

The effects of methylmercury (MeHg) on exposed populations are a public health problem. In contrast to widely studied neurological damage, few cardiovascular changes have been described. Our group evaluated the cardiotoxicity of a cumulative dose of 70 mg.kg⁻¹ fractioned over a 14-day [...] Read more.

The effects of methylmercury (MeHg) on exposed populations are a public health problem. In contrast to widely studied neurological damage, few cardiovascular changes have been described. Our group evaluated the cardiotoxicity of a cumulative dose of 70 mg.kg⁻¹ fractioned over a 14-day exposure period in mice (MeHg70 group). The effects of MeHg on proteins relevant to cardiac mitochondrial function were also investigated. The results obtained showed a reduction in oxygen consumption in the two settings. In cardiac tissue samples in oxygraphy studies, this reduction was related to a lower efficiency of complexes II and V, which belong to the oxidative phosphorylation system. In vivo, mice in the MeHg70 group presented lower oxygen consumption and running tolerance, as shown by ergometric analyses. Cardiac stress was evident in the MeHg70 group, as indicated by a marked increase in the level of the mRNA encoding atrial natriuretic peptide. Electrocardiogram studies revealed a lower heart rate at rest in the animals from the MeHg70 group, as well as prolonged left ventricular depolarisation and repolarisation. Through echocardiographic analysis, reductions in the left ventricular ejection fraction and left ventricular wall thickness of approximately 10% and 20%, respectively, were detected. These results indicate that the oral intake of MeHg can decrease cardiac function and oxidative metabolism. This finding highlights the importance of monitoring MeHg levels in humans and animals in contaminated areas, as well as periodically carrying out cardiac function tests. Full article

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

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13 pages, 3426 KiB

Open AccessArticle

Variations in Oil Occurrence State and Properties during High-Speed Stirring Treatment of Oily Sludge

by Yuwei Bao, Yimin Zhu, Yang Liu, Jiao Zhao, Xiaojia Tang, Tie Li, Yin Wang, Xianmeng Liu and Hao Zhang

Toxics 2024, 12(10), 711; https://doi.org/10.3390/toxics12100711 - 29 Sep 2024

Abstract

Oily sludge (OS) has long been regarded as a hazardous waste, and improper disposal may lead to serious environmental concerns and human health risks. Despite various methods having been proposed and applied to the treatment of OS, the oil occurrence states and properties [...] Read more.

Oily sludge (OS) has long been regarded as a hazardous waste, and improper disposal may lead to serious environmental concerns and human health risks. Despite various methods having been proposed and applied to the treatment of OS, the oil occurrence states and properties in sludge are rarely characterized, which may directly link to the selection and effectiveness of treatment methods. Here, confocal laser scanning microscopy (CLSM), X-ray diffraction (XRD), gas chromatography (GC), and four components (SARA) analysis were utilized to characterize the changes in the oil occurrence states and compositions in OS samples before and after high-speed stirring (HSS) treatment. Our results show a substantial reduction in the oil concentration of OS after HSS treatment (from 32.98% to 1.65%), while SARA analysis reveals a similar oil composition before and after treatment, suggesting the broad applicability of HSS in removing oil and its insignificant selectivity towards various hydrocarbon components. This is further supported by the total petroleum hydrocarbon (TPH) analysis results, which show that the separated oil phase has a hydrocarbon composition similar to that of the original OS sample. The CLSM and fluorescence analysis suggest a homogeneous distribution of oil in the sludge, with relatively light components more concentrated in the pore systems between coarse mineral particles, whereas relatively heavy components tend to coexist with clay minerals. After HSS cleaning, both light and heavy components are removed to varying degrees, but light components are preferentially removed while heavy components tend to be retained in the sludge due to adsorption by clay minerals. This is consistent with TPH analysis, where a significant decrease in n-alkanes with lower carbon numbers (n-C14 to n-C20) was observed in the residual sample. Our findings demonstrate the dynamic response of oil occurrence states and compositions to the OS treatment process and highlight the importance of characterizing these fundamental properties prior to the selection of OS treatment methods. Full article

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

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102 pages, 805 KiB

Open AccessReview

Short-Half-Life Chemicals: Maternal Exposure and Offspring Health Consequences—The Case of Synthetic Phenols, Parabens, and Phthalates

by Delphine Rousseau-Ralliard, Jeanne Bozec, Marion Ouidir, Nicolas Jovanovic, Véronique Gayrard, Namya Mellouk, Marie-Noëlle Dieudonné, Nicole Picard-Hagen, Maria-José Flores-Sanabria, Hélène Jammes, Claire Philippat and Anne Couturier-Tarrade

Toxics 2024, 12(10), 710; https://doi.org/10.3390/toxics12100710 - 29 Sep 2024

Abstract

Phenols, parabens, and phthalates (PPPs) are suspected or known endocrine disruptors. They are used in consumer products that pregnant women and their progeny are exposed to daily through the placenta, which could affect offspring health. This review aims to compile data from cohort [...] Read more.

Phenols, parabens, and phthalates (PPPs) are suspected or known endocrine disruptors. They are used in consumer products that pregnant women and their progeny are exposed to daily through the placenta, which could affect offspring health. This review aims to compile data from cohort studies and in vitro and in vivo models to provide a summary regarding placental transfer, fetoplacental development, and the predisposition to adult diseases resulting from maternal exposure to PPPs during the gestational period. In humans, using the concentration of pollutants in maternal urine, and taking the offspring sex into account, positive or negative associations have been observed concerning placental or newborn weight, children’s BMI, blood pressure, gonadal function, or age at puberty. In animal models, without taking sex into account, alterations of placental structure and gene expression linked to hormones or DNA methylation were related to phenol exposure. At the postnatal stage, pollutants affect the bodyweight, the carbohydrate metabolism, the cardiovascular system, gonadal development, the age of puberty, sex/thyroid hormones, and gamete quality, but these effects depend on the age and sex. Future challenges will be to explore the effects of pollutants in mixtures using models and to identify the early signatures of in utero exposure capable of predicting the health trajectory of the offspring. Full article

(This article belongs to the Section Reproductive and Developmental Toxicity)

16 pages, 2034 KiB

Open AccessArticle

Soil Actinobacteria Exhibit Metabolic Capabilities for Degrading the Toxic and Persistent Herbicide Metribuzin

by Hadjer Rebai, Essam Nageh Sholkamy, Mohamed A. A. Abdelhamid, Pratheesh Prakasam Thanka, Ashraf Aly Hassan, Seung Pil Pack, Mi-Ran Ki and Allaoueddine Boudemagh

Toxics 2024, 12(10), 709; https://doi.org/10.3390/toxics12100709 - 29 Sep 2024

Abstract

Metribuzin, a widely used triazine herbicide, persists in agricultural soils and poses significant environmental pollution threats globally. The aim of this study was to investigate the biodegradation of metribuzin by actinobacterial strains in vitro at different environmental conditions. From an initial screen of [...] Read more.

Metribuzin, a widely used triazine herbicide, persists in agricultural soils and poses significant environmental pollution threats globally. The aim of this study was to investigate the biodegradation of metribuzin by actinobacterial strains in vitro at different environmental conditions. From an initial screen of 12 actinobacterial strains, four bacteria exhibited robust growth in the presence of the metribuzin as the sole carbon source at 50 mg/L concentration. The optimization of metribuzin biodegradation under different conditions (pH, temperature and inoculum size) using a spectrophotometric method revealed that maximum degradation of metribuzin occurred at a pH of 7.2, a temperature 30 °C, and at an inoculum volume of 4%. Subsequent GC-MS validation confirmed the remarkable biodegradation capabilities of the actinobacterial isolates, where the strain C1 showed the highest rate of metribuzin degradation of 83.12%. Detailed phylogenetic identified the active strains as Streptomyces toxytricini (CH), Streptomyces stelliscabiei (B2), and two Streptomyces heliomycini (C1, C3). Structural analysis by ATR-FTIR spectroscopy confirmed the extensive biotransformation of the herbicide molecule. Our findings highlight the immense untapped potential of soil actinobacteria, particularly the Streptomyces heliomycini C1 strain, as versatile bioremediation agents for removing persistent agrochemical pollutants. Full article

(This article belongs to the Special Issue Toxicity Characterization, Detection and Remediation of Contaminants in Soils and Groundwater 2.0)

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30 pages, 3887 KiB

Open AccessArticle

Fish Health Altered by Contaminants and Low Water Temperatures Compounded by Prolonged Regional Drought in the Lower Colorado River Basin, USA

by Steven L. Goodbred, Sr., Reynaldo Patiño, David A. Alvarez, Darren Johnson, Deena Hannoun, Kathy R. Echols and Jill A. Jenkins

Toxics 2024, 12(10), 708; https://doi.org/10.3390/toxics12100708 - 28 Sep 2024

Abstract

The goal of this study was to assess health of male Common Carp (carp, Cyprinus carpio) at four sites with a wide range in environmental organic contaminant (EOC) concentrations and water temperatures in Lake Mead National Recreation Area NV/AZ, US, and the [...] Read more.

The goal of this study was to assess health of male Common Carp (carp, Cyprinus carpio) at four sites with a wide range in environmental organic contaminant (EOC) concentrations and water temperatures in Lake Mead National Recreation Area NV/AZ, US, and the potential influence of regional drought. Histological and reproductive biomarkers were measured in 17–30 carp at four sites and 130 EOCs in water per site were analyzed using passive samplers in 2010. Wide ranges among sites were noted in total EOC concentrations (>10Xs) and water temperature/degree days (10Xs). In 2007/08, total polychlorinated biphenyls (tPCBs) in fish whole bodies from Willow Beach (WB) in the free-flowing Colorado River below Hoover Dam were clearly higher than at the other sites. This was most likely due to longer exposures in colder water (12–14 °C) and fish there having the longest lifespan (up to 54 years) for carp reported in the Colorado River Basin. Calculated estrogenicity in water exceeded long-term, environmentally safe criteria of 0.1–0.4 ng/L by one to three orders of magnitude at all sites except the reference site. Low ecological screening values for four contaminants of emerging concern (CEC) in water were exceeded for one CEC in the reference site, two in WB and Las Vegas Bay and three in the most contaminated site LVW. Fish health biomarkers in WB carp had 25% lower liver glycogen, 10Xs higher testicular pigmented cell aggregates and higher sperm abnormalities than the reference site. Sperm from LVW fish also had significantly higher fragmentation of DNA, lower motility and testis had lower percent of spermatozoa, all of which can impair reproduction. Projections from a 3D water quality model performed for WB showed that EOC concentrations due to prolonged regional drought and reduced water levels could increase as high as 135%. Water temperatures by late 21st century are predicted to rise between 0.7 and 2.1 °C that could increase eutrophication, algal blooms, spread disease and decrease dissolved oxygen over 5%. Full article

(This article belongs to the Special Issue Risks to Aquatic Animal Health Conditions in Environmental Extremes: Research and Management)

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24 pages, 799 KiB

Open AccessReview

Breast Cancer-Related Chemical Exposures in Firefighters

by Bethsaida Cardona, Kathryn M. Rodgers, Jessica Trowbridge, Heather Buren and Ruthann A. Rudel

Toxics 2024, 12(10), 707; https://doi.org/10.3390/toxics12100707 - 28 Sep 2024

Abstract

To fill a research gap on firefighter exposures and breast cancer risk, and guide exposure reduction, we aimed to identify firefighter occupational exposures linked to breast cancer. We conducted a systematic search and review to identify firefighter chemical exposures and then identified the [...] Read more.

To fill a research gap on firefighter exposures and breast cancer risk, and guide exposure reduction, we aimed to identify firefighter occupational exposures linked to breast cancer. We conducted a systematic search and review to identify firefighter chemical exposures and then identified the subset that was associated with breast cancer. To do this, we compared the firefighter exposures with chemicals that have been shown to increase breast cancer risk in epidemiological studies or increase mammary gland tumors in experimental toxicology studies. For each exposure, we assigned a strength of evidence for the association with firefighter occupation and for the association with breast cancer risk. We identified twelve chemicals or chemical groups that were both linked to breast cancer and were firefighter occupational exposures, including polycyclic aromatic hydrocarbons, volatile aromatics, per- and polyfluoroalkyl substances, persistent organohalogens, and halogenated organophosphate flame retardants. Many of these were found at elevated levels in firefighting environments and were statistically significantly higher in firefighters after firefighting or when compared to the general population. Common exposure sources included combustion byproducts, diesel fuel and exhaust, firefighting foams, and flame retardants. Our findings highlight breast-cancer-related chemical exposures in the firefighting profession to guide equitable worker’s compensation policies and exposure reduction. Full article

(This article belongs to the Special Issue Firefighters’ Occupational Exposures and Health Risks)

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