Mechanisms of Chromium-Induced Toxicity

The Protective Effects of Taurine, a Non-essential Amino Acid, Against Metals Toxicities: A Review Article

Taurine is a non-proteinogenic amino acid derived from cysteine. It is involved in several phenomena such as the regulation of growth and differentiation, osmoregulation, neurohormonal modulation, and lipid metabolism. Taurine is important because of its high levels in several tissues such as the central nervous system (CNS), heart, skeletal muscles, retinal membranes, and platelets. In this report, we present the functional properties of taurine indicating that it has potential effects on various metal toxicities. Therefore, a comprehensive literature review was performed using the Scopus, PubMed, and Web of Science databases. According to the search keywords, 61 articles were included in the study. The results indicate that taurine protects tissues against metal toxicity through enhancement of enzymatic and non-enzymatic antioxidant capacity, modulation of oxidative stress, anti-inflammatory and anti-apoptotic effects, involvement in different molecular pathways, and interference with the activity of various enzymes. Taken together, taurine is a natural supplement that presents antitoxic effects against many types of compounds, especially metals, suggesting public consumption of this amino acid as a prophylactic agent against the incidence of metal toxicity.

Electrodepositing Ag on Anodized Stainless Steel for Enhanced Antibacterial Properties and Corrosion Resistance

Antibacterial stainless steels have been widely used in biomedicine, food, and water treatment. However, the current antibacterial stainless steels face challenges in balancing corrosion resistance and antibacterial effectiveness, limiting their application range and lifespan. In this study, an oxide layer sealed with antibacterial Ag particles was constructed on the surface of 304 stainless steel through anodizing and electrodeposition, and the process parameters were optimized for achieving long-term antibacterial properties. The electrochemical tests demonstrated that the composite coating effectively enhanced the corrosion resistance of 304 stainless steel. The X-ray photoelectron spectroscopy analysis revealed the close binding mechanism between the Ag particles and the micropores in the oxide layer. Furthermore, the antibacterial stainless steel has an antibacterial rate of 99% against Escherichia coli (E. coli) and good biocompatibility. This study provides an effective approach for designing efficient, stable, and safe antibacterial stainless steel.

Chromium, tungsten and vanadium sediment-porewater geochemistry under oxic and anoxic redox conditions: Implication for their remobilization

Global chromium (Cr), tungsten (W), and vanadium (V) cycles are emerging concerns due to their toxicities to ecosystems. However, a comprehensive understanding of their geochemical reactions and controls at the sediment-water interface remains largely unknown. This knowledge gap hinders the assessment of their potential remobilization in Earth's surface environments threatened by hypoxic conditions. We collected pore water and sediment samples from the undisturbed Castle Lake, situated in the Klamath-Siskiyou Mountains of northern California, USA, to investigate the geochemical controls responsible for the fixation and release of Cr, W, and V under redox transitions from oxia to anoxia during early diagenesis. The results show that, under oxic conditions, authigenic Cr, W, and V ratios in porewater account for approximately 4.7 %, <0.1 %, and < 0.1 %, respectively, whereas their ratios display around ten times increase under anoxic conditions with average values of 62.4 % for Cr, 4.1 % for W, and 1.1 % for V. Our combined thermodynamic calculation and diagenetic analyses show that the sequestration and release of Cr, W, and V are intimately associated with Fe cycle under anoxic conditions. In contrast, under oxygenated conditions, only Cr and V geochemical behaviors are significantly affected by Fe cycle, while the adsorption of W to Fe minerals is probably inhibited by dissolved organic matter. Furthermore, we suggest that the Cr, W, and V pollution could become significant in coastal and inland water areas where redox conditions oscillate between oxia and anoxia, with intensified water deoxygenation, acidity, and eutrophication.

Heavy metals: toxicity and human health effects

Heavy metals are naturally occurring components of the Earth's crust and persistent environmental pollutants. Human exposure to heavy metals occurs via various pathways, including inhalation of air/dust particles, ingesting contaminated water or soil, or through the food chain. Their bioaccumulation may lead to diverse toxic effects affecting different body tissues and organ systems. The toxicity of heavy metals depends on the properties of the given metal, dose, route, duration of exposure (acute or chronic), and  extent of bioaccumulation. The detrimental impacts of heavy metals on human health are largely linked to their capacity to interfere with antioxidant defense mechanisms, primarily through their interaction with intracellular glutathione (GSH) or sulfhydryl groups (R-SH) of antioxidant enzymes such as superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione reductase (GR), and other enzyme systems. Although arsenic (As) is believed to bind directly to critical thiols, alternative hydrogen peroxide production processes have also been postulated. Heavy metals are known to interfere with signaling pathways and affect a variety of cellular processes, including cell growth, proliferation, survival, metabolism, and apoptosis. For example, cadmium can affect the BLC-2 family of proteins involved in mitochondrial death via the overexpression of antiapoptotic Bcl-2 and the suppression of proapoptotic (BAX, BAK) mechanisms, thus increasing the resistance of various cells to undergo malignant transformation. Nuclear factor erythroid 2-related factor 2 (Nrf2) is an important regulator of antioxidant enzymes, the level of oxidative stress, and cellular resistance to oxidants and has been shown to act as a double-edged sword in response to arsenic-induced oxidative stress. Another mechanism of significant health threats and heavy metal (e.g., Pb) toxicity involves the substitution of essential metals (e.g., calcium (Ca), copper (Cu), and iron (Fe)) with structurally similar heavy metals (e.g., cadmium (Cd) and lead (Pb)) in the metal-binding sites of proteins. Displaced essential redox metals (copper, iron, manganese) from their natural metal-binding sites can catalyze the decomposition of hydrogen peroxide via the Fenton reaction and generate damaging ROS such as hydroxyl radicals, causing damage to lipids, proteins, and DNA. Conversely, some heavy metals, such as cadmium, can suppress the synthesis of nitric oxide radical (NO·), manifested by altered vasorelaxation and, consequently, blood pressure regulation. Pb-induced oxidative stress has been shown to be indirectly responsible for the depletion of nitric oxide due to its interaction with superoxide radical (O2·-), resulting in the formation of a potent biological oxidant, peroxynitrite (ONOO-). This review comprehensively discusses the mechanisms of heavy metal toxicity and their health effects. Aluminum (Al), cadmium (Cd), arsenic (As), mercury (Hg), lead (Pb), and chromium (Cr) and their roles in the development of gastrointestinal, pulmonary, kidney, reproductive, neurodegenerative (Alzheimer's and Parkinson's diseases), cardiovascular, and cancer (e.g. renal, lung, skin, stomach) diseases are discussed. A short account is devoted to the detoxification of heavy metals by chelation via the use of ethylenediaminetetraacetic acid (EDTA), dimercaprol (BAL), 2,3-dimercaptosuccinic acid (DMSA), 2,3-dimercapto-1-propane sulfonic acid (DMPS), and penicillamine chelators.

Mineral composition in mussel Mytilus galloprovincialis and clam Tapes decussatus from Faro Lake of Messina: risk assessment for human health

Bivalve are exposed to a wide range of contaminants, some of which may be toxic to human health. The aim of this study was to detect essential and non-essential elements such as Na, Ca, Mg, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Pb, Hg, Be and Co in water, sediments, and Mytilus galloprovincialis and Tapes decussatus from Faro Lake. It is a lake of marine origin located on the northern coast of Messina (Sicily), where shellfish farming has been practiced for many years. Metals were analysed by a single quadrupole inductively coupled plasma mass spectrometer (ICP-MS), except for Hg, which was quantified using a direct mercury analyser (DMA-80). The study evaluated the nutritional intake of elements through the ingestion of clams and mussels and the potential health risks to consumers. The lead levels found in M. galloprovincialis were below the LOQ, while in T. decussatus the concentrations were below the limit indicated by European Regulation 915/2023. Statistical analysis was carried out on M. galloprovincialis and T. decussatus samples using SPSS 27 and the data showed highly significant differences between the two species (p < 0.001). Cadmium (Cd) and mercury (Hg) concentrations were also below the legal limit in all samples analyzed. This study has shown that clams and mussels are a source of sodium (Na) with a Recommended Dietary Allowance (RDA) of 36% in M. galloprovincialis and 77% in T. decussatus. The percentages obtained for calcium (Ca) and magnesium (Mg) were 17%-19% and 18%-8%, respectively. The RDA of chromium (Cr) was of 191% for M. galloprovincialis and of 405% for T. decussatus. The Fe percentages were 92% and 169% for M. galloprovincialis and T. decussatus, respectively. The concentrations of the other metals observed in the two bivalve species of Lake Faro were generally lower than the Tolerable Weekly Intake (TWI) values estimated as a risk to human health.

Nutritional Risks of Heavy Metals in the Human Diet-Multi-Elemental Analysis of Energy Drinks

Background: In recent years, the consumption of energy drinks (EDs) by adolescents and young adults has increased significantly, so concerns have been raised about the potential health risks associated with excessive ED consumption. Most analyses on EDs focus on the caffeine content. Research on the content of minerals (essential and toxic) in energy drinks can be considered scarce. Therefore, there is a need for research stating the actual status of heavy metal content in commercially available energy drinks. Methods: This research presents the determination of the total concentrations of macro-elements and trace elements (TEs), such as Na, K, Mg, Ca, Al, Cr, Co, Cu, Fe, Mn, Ni, B, Zn, V, Sr, Ba, Pb, Cd, and As in nine samples of energy drinks using inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) techniques. Results: The order in the content of macro-minerals in the EDs was as follows: Na > K > Mg > Ca. The results showed that ED 1, ED 3, and ED 7 samples had the highest micro-mineral concentrations. All the samples had a hazard quotient and hazard index < 1, indicating no non-carcinogenic risk from exposure to single or multiple heavy metals in both the adolescent and adult age groups. Some samples exceeded the threshold limit of acceptable cancer risk for As, Ni, and Cr in both adolescents and adults. Conclusions: This assessment showed that in addition to health implications based on the caffeine content of EDs, there might be a carcinogenic risk associated with the toxic element content of these beverages. This research also highlights notable differences in the TE levels among various ED brands, which may have important implications for consumer well-being and health.

Rosemary officinalis extract mitigates potassium dichromate-induced testicular degeneration in male rats: Insights from the Nrf2 and its target genes signaling pathway

This study aimed to investigate the protective effects of Rosemary ethanol extract (ROEE) on testicular damage induced by potassium Dichromate (PDC) in male rats regarding the signaling pathway of Nrf2 and its target genes and proteins. A total of 28 male rats were divided into four groups: control, PDC only (15 mg/kg b.w. orally), PDC + low dose ROEE (220 mg/kg b.w.), and PDC + high dose ROEE (440 mg/kg b.w.). After 28 days of consecutive treatment, the rats were sacrificed for histological, immunohistochemistry, and biochemical analyses. The results revealed that the ROEE treatment up-regulated the Nrf2 and its target genes (NQO1, HO-1) mRNA expressions compared to the PDC group. correspondingly, the protein levels of GCLM, GSH, SOD, and catalase were significantly increased in the ROEE-treated animals compared to the PDC-treated animals. Furthermore, ROEE administration led to increased serum levels of testosterone (T4) and decreased levels of estrogen (E2) compared to the PDC group. Semen analysis and histopathology demonstrated that ROEE administration significantly improved spermatological impairment caused by PDC. The immunoexpression of cytoplasmic HSP-90 was reduced in the ROEE-treated groups, while the expression of androgen receptor (AR) was markedly improved. ROEE exhibited protective effects against PDC-induced testicular damage, likely due to its antioxidant properties. However, further investigation is required to elucidate the underlying mechanisms of action.

Pharmacotherapeutic potential of bilobetin to combat chromium induced hepatotoxicity via regulating TLR-4, Nrf-2/Keap-1, JAK1/STAT3 and NF-κB pathway: A pharmacokinetic and molecular dynamic approach

BACKGROUND

Chromium (Cr) is one of the top-notch noxious heavy metals that is documented to exert deleterious effects on various body organs including the liver. Bilobetin (BLB) is a natural flavonoid which exhibits a wide range of medicinal properties.

AIM

This trial was executed to investigate the pharmacotherapeutic potential of BLB to avert Cr instigated hepatotoxicity via modulating TLR4, JAK1/STAT3, Nrf-2/Keap-1 and NF-κB pathway.

RESEARCH LAYOUT

Our trial was executed on thirty-six male albino rats that were segregated into four equal groups including the control, Cr (10 mg/kg), Cr (10 mg/kg) + BLB (12 mg/kg) and BLB (12 mg/kg) alone treated group. Various biochemical parameters were assessed by using qRT-PCR, molecular docking, molecular dynamic simulation and histological approaches.

FINDINGS

Our results revealed that Cr administration significantly impaired the health of hepatic tissues by reducing the gene expression of Nrf-2 and its downregulating genes while promoting the levels of oxidative stress markers (ROS and MDA). Moreover, Cr administration upregulated the hepatic enzymes including ALT, GGT, AST, and ALP while concurrently decreasing the levels of total protein and albumin. Cr exposure also elevated the gene expression of pro-inflammatory cytokines including toll-like receptor 4 (TLR4), high mobility group box 1 (HMGB1) nuclear factor kappa B (NF-κB), Janus kinase 1 (JAK1), signal transducer and activator of transcription 3 (STAT3), tumor necrosis factor alpha (TNF-α), C-reactive proteins, interferon-gamma inducible protein-10 (IP-10), Interleukin beta-1(IL-1β), monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2). Hepatic apoptosis was observed to be elevated following the Cr intoxication. Nonetheless, BLB treatment remarkably alleviated the hepatic damages via regulating the biochemical as well as histological profile of liver. Our findings are further endorsed by molecular docking analysis that demonstrated that BLB exhibit strong binding affinity to Keap-1 and STAT3 thus supporting its efficient hepatoprotective potential.

CONCLUSION

BLB protected the hepatic tissues via regulating Cr induced impairments. These findings were confirmed by molecular docking and molecular dynamic simulation analysis.

Stress granules play a critical role in hexavalent chromium-induced malignancy in a G3BP1 dependent manner

Stress granules (SGs) are dynamic membraneless organelles influencing multiple cellular pathways including cell survival, proliferation, and malignancy. Hexavalent chromium [Cr(VI)] is a toxic heavy metal associated with severe environmental health risks. Low-level environmental exposure to Cr(VI) has been reported to cause cancer, but the role of SGs in Cr(VI)-induced health effects remains unclear. This study was intended to elucidate the impact of Cr(VI) exposure on SG dynamics and the role of SGs in Cr(VI)-induced malignancy. Results showed that both acute exposure to high concentration of Cr(VI) and prolonged exposure to low concentration of Cr(VI)-induced SG formation in human bronchial epithelium BEAS-2B cells. Cells pre-exposed to Cr(VI) exhibited a more robust SG response compared to cells without pre-exposure. An up-regulated SG response was associated with increased malignant properties in cells exposed to low concentration Cr(VI) for an extended period of time up to 12 months. Knocking out the SG core protein G3BP1 in Cr(VI)-transformed (CrT) cells reduced SG formation and malignant properties, including proliferation rate, sphere formation, and malignant markers. The results support a critical role for SGs in mediating Cr(VI)-induced malignancy in a G3BP1-dependent manner, representing a novel mechanism and a potential therapeutic target.

Seaweed liquid extract AS novel sustainable solutions for phycobioremediation plant germination, and feed additive for marine invertebrate copepod

Several studies have shown the importance of using seaweed liquid extract (True-Algae-Max, TAM) as a fish feed additive, and fish-water conditioner. In addition, TAM has demonstrated significant growth improvement when used as a plant growth biostimulant. This study investigates whether seaweed liquid extract (TAM) can achieve good results in new experimental fields such as chromium remediation, plant germination, and live feed supplementation for marine invertebrate Copepod (Oithona nana). In this study, several doses of TAM were tested, for the first time, for their impact on the remediation of chromium (Cr6+) ions from aqueous solutions and as an aqua feed additive for marine copepods (Oithona nana). In addition, it has been tested as promising for the seed germination of Fenugreek (Trigonella foenum-graecum) and Faba bean (Vicia faba L.). The most important factors influencing the removal (%) of Cr6+, identified using a two-level Plackett-Burman factorial design, were selected for additional optimization utilizing a rotatable central composite design. The maximum adsorption of Cr6+ was 93.65% under ideal operating circumstances, which included an initial Cr6+ concentration of 60 mg L-1, a temperature of 25 °C, a pH of 3, a TAM biomass of 0.05 g, and a contact time of 60 min at agitation conditions. Plackett-Burman design data shows the significance of each factor and how well the model fits the Cr6+ removal. The results of the germination experiment revealed that the highest significant increase in seed germination was achieved using a TAM level of 0.30 mg mL-1 with V. faba (88%) and 0.03 mg mL-1 with T. foenum-graecum (96.6%). Additionally, compared to the control group, TAM at a level of 0.037 mg mL-1 showed high root length enhancement on V. faba (184%) and T. foenum-graecum (188%). The results of the copepod O. nana feeding additive experiment found that the group fed on starch supplemented with TAM at a level of 0.3 mL L-1, compared to the control group that fed starch only, showed the highest increment in population growth (134.74%), fecundity (270.16%), and population composition of males (133.45%), adults (120.37%), and nauplius (203.18%). Moreover, compared to the control group, the copepod that fed starch supplemented with TAM levels achieved the highest Omega-9 content. In conclusion, it is shown that TAM is a feasible, efficient, and sustainable solution for biodegradable adsorbent for the Cr6+ from aqueous solution, enhances plant seed germination and root length, and is a novel feed additive for marine copepod O. nana, especially in marine invertebrate hatcheries.

Quantitative assessment of Nigella sativa and conjugated silver nanoparticles against hexavalent chromium toxic effects on sperm function

BACKGROUND

Infertility has been observed as one of the major issues in humans, one known risk factor is heavy metals.

METHODS

The main focus of the present research was to assess the toxic effect of hexavalent chromium (Cr (VI)) on sperm and its mitigation by Nigella sativa seed extract (NS) and its conjugated silver nanoparticles (NS + NP). In the present study, we administered 1.5 mg/kg body of Cr (VI) orally in mice for 60 days routinely, to induce toxicity in testes and effect on sperm production and motility in male mice. NS and NS + NP (50 mg/kg body weight) were administered to evaluate protective action against Cr (VI). The sperm were analyzed by computer-assisted semen analysis (CASA) and chromium concentration in testicular tissue was measured via the atomic absorption spectrophotometer.

RESULTS

The CASA analysis showed that Cr (VI) was directly linked with a decline in sperm concentration, motility, distance, velocity, straightness, and head beat frequency attributes. However, the administration of Nigella sativa seed extract and its green synthesized silver nanoparticles improved sperm concentration, motility, distance, velocity, straightness, and head beat frequency. The chromium content in the testes of Cr-exposed animals significantly increased, which negatively affected sperm parameters. However, Nigella sativa and Nigella sativa conjugated silver nanoparticles appeared to help in the removal of Cr content from testes hence improving the sperm parameters in exposed mice.

CONCLUSION

The decrease in Cr concentration improved sperm quality and quantity, hence, improve male fertility.

Biochar solutions: Slow and fast pyrolysis effects on chromium stress in rapeseed roots

Chromium (Cr) contamination in agricultural soils, largely due to industrial activities, poses a significant threat to plant growth and productivity. This study examines the effects of Cr stress at concentrations of 100 and 200 mg of K2Cr2O7 per kg soil on rapeseed (Brassica napus) roots and evaluates the mitigating potential of biochar. Biochar, produced through both slow and fast pyrolysis and applied at 30 g per kg soil, was investigated for its ability to neutralize Cr toxicity. Our findings indicate that Cr stress significantly decreased the growth and physiological functions of rapeseed roots. However, biochar application improved soil pH, cation exchange capacity, and the uptake of essential nutrients such as nitrogen, phosphorus, potassium, calcium, and magnesium. Additionally, biochar enhanced the production of osmotic regulators like glycine betaine and soluble proteins, as well as indole acetic acid, promoting better root growth and water uptake under Cr stress. Notably, biochar reduced Cr availability and absorption in rapeseed roots, leading to lower levels of stress-related hormones such as abscisic acid, salicylic acid, and jasmonic acid. Among the biochars tested, slow pyrolysis biochar was more effective than fast pyrolysis biochar in mitigating Cr toxicity. These results highlight the potential of slow pyrolysis biochar as a sustainable strategy to alleviate Cr pollution and enhance plant resilience in contaminated soils.

Epigenetic toxicity of heavy metals - implications for embryonic stem cells

Exposure to heavy metals, such as cadmium, nickel, mercury, arsenic, lead, and hexavalent chromium has been linked to dysregulated developmental processes, such as impaired stem cell differentiation. Heavy metals are well-known modifiers of the epigenome. Stem and progenitor cells are particularly vulnerable to exposure to potentially toxic metals since these cells rely on epigenetic reprogramming for their proper functioning. Therefore, exposure to metals can impair stem and progenitor cell proliferation, pluripotency, stemness, and differentiation. In this review, we provide a comprehensive summary of current evidence on the epigenetic effects of heavy metals on stem cells, focusing particularly on DNA methylation and histone modifications. Moreover, we explore the underlying mechanisms responsible for these epigenetic changes. By providing an overview of heavy metal exposure-induced alterations to the epigenome, the underlying mechanisms, and the consequences of those alterations on stem cell function, this review provides a foundation for further research in this critical area of overlap between toxicology and developmental biology.

Assessing chromium toxicity across aquatic and terrestrial environments: a cross-species review

Chromium (Cr) toxicity, even at low concentrations, poses a significant health threat to various environmental species. Cr is found in the environment in two oxidation states that differ in their bioavailability and toxicity. While Cr(III) is essential for glucose metabolism, the oxyanion chromate Cr(VI) is mostly of anthropogenic origin, toxic, and carcinogenic. The sources of Cr in the environment are multiple, including geochemical processes, disposal of industrial waste, and industrial wastewater. Cr pollution may consequently impact the health of numerous plant and animal species. Despite that, the number of published studies on Cr toxicity across environmental species remained mainly unchanged over the past two decades. The presence of Cr in the environment affects several plant physiological processes, including germination or photosynthesis, and consequently impacts growth, and lowers agricultural production and quality. Recent research has also reported the toxic effects of Cr in different aquatic and terrestrial organisms. Whereas some species showed sensitivity, others exhibited tolerance. Hence, this review discusses the understanding of the ecotoxicological effect of Cr on different plant and animal groups and serves as a concise source of consolidated information and a valuable reference for researchers and policymakers in an understanding of Cr toxicity. Future directions should focus on expanding research efforts to understand the mechanisms underlying species-specific responses to Cr pollution.

Heavy metal ion sensing strategies using fluorophores for environmental remediation

The main aim of this review is to provide a holistic summary of the latest advances within the research area focusing on the detection of heavy metal ion pollution, particularly the sensing strategies. The review explores various heavy metal ion detection approaches, encompassing spectrometry, electrochemical methods, and optical techniques. Numerous initiatives have been undertaken in recent times in response to the increasing demand for fast, sensitive, and selective sensors. Notably, fluorescent sensors have acquired prominence owing to the numerous advantages such as good specificity, reversibility, and sensitivity. Further, this review also explores the advantages of various nanomaterials employed in sensing heavy metal ions. In this regard, exclusive emphasis is placed on fluorescent nanomaterials based on organic dyes, quantum dots, and fluorescent aptasensors for metal ion removal from aqueous systems, and to identify the fate of heavy metal ions in the natural environment.

Recent advancements in bamboo nanocellulose-based bioadsorbents and their potential in wastewater applications: A review

The research interest in sustainable and eco-friendly materials based on natural sources has increased dramatically due to their recyclability, biodegradability, compatibility, and nontoxic behavior. Recently, nanocellulose-based green composites are under extensive exploration and have gained popularity among researchers owing to their lightweight, lost cost, low density, excellent mechanical and physical characteristics. This review provides a comprehensive overview of the recent advancements in the extraction, modification, and application of bamboo nanocellulose as a high-performance bioadsorbent. Bamboo, a rapidly renewable resource, offers an eco-friendly alternative to traditional materials due to its abundant availability and unique structural properties. Significantly, bamboo comprises a considerable amount of cellulose, approximately 40 % to 50%, rendering it a valuable source of cellulose fiber for the fabrication of cellulose nanocrystals. The review highlights different various modification techniques which enhance the adsorption capacities and selectivity of bamboo nanocellulose. Furthermore, the integration of bamboo nanocellulose into novel composite materials and its performance in removing contaminants such as heavy metals, dyes, and organic pollutants from wastewater are critically analyzed. Emphasis is placed on the mechanisms of adsorption, regeneration potential, and the economic and environmental benefits of using bamboo-based bioadsorbents. The findings underscore the potential of bamboo nanocellulose to play a pivotal role in developing sustainable wastewater treatment technologies, offering a promising pathway towards cleaner water and a greener future.

The toxicological analysis of problematic and sophisticated elements (Ni, Cr, and Se) in Food for Special Medical Purposes (FSMP) using in pharmacotherapy and clinical nutrition for oncological patients available in Polish pharmacies

This study focuses on FSMPs for oncologic patients, specifically analyzing the toxicological profiles of nickel (Ni), chromium (Cr), and selenium (Se) within these products available in Polish pharmacies. The presence of these elements was quantified using inductively coupled plasma mass spectrometry (ICP-MS). Results indicated variations in the concentrations of Ni, Cr, and Se across different FSMP samples, with some products exceeding the acceptable limits set by regulatory guidelines. The study highlights the potential health risks associated with nickel exposure, including dermatitis and carcinogenesis, and the complex roles of chromium and selenium, which can be both beneficial and harmful depending on their levels. Our findings reveal significant variability in the elemental content across different FSMP products, i.e.: Ni: 0.155-25.488 μg/portion, Cr: 0.076-28.726 μg/portion and Se: 0.083-20.304 μg/portion). Notably, selenium levels in FSMPs showed considerable discrepancies compared to manufacturers' declarations, averaging only about 20% of the stated values. Regulatory assessments based on the Acceptable Daily Intake (ADI) and Permitted Daily Exposure (PDE) descriptors indicated that the estimated weekly intake of Ni, Cr, and Se from these FSMPs did not exceed the provisional tolerable weekly intake (PTWI) values. However, the highest Ni content was 30.58% of the PTWI, raising concerns about potential health risks, including dermatitis and carcinogenesis. The results for Cr underscored the necessity for careful monitoring due to its potential toxic effects. Selenium, despite its essential role, showed levels inadequate to meet the Recommended Dietary Allowance (RDA), potentially impacting its intended health benefits.

Chromium uptake and its impact on antioxidant level, photosynthetic machinery, and related gene expression in Brassica napus cultivars

The development of heavy metals, particularly chromium (Cr)-tolerant crop cultivars, is hampered due to lack of understanding of the mechanisms behind Cr stress tolerance. In this study, two Brassica napus cultivars, ZS758 and ZD622, were compared for Cr stress resistance by using the chlorophyll a fluorescence technique and biochemical characteristics. In both cultivars, Cr stress dramatically decreased PSII and PSI efficiency, biomass accumulation, and antioxidant enzyme levels. Although, cultivar ZS758 showed reduction in oxidative stress by decreasing the production of reactive oxygen species (ROS) in terms of reduced H2O2 and MDA content and increased enzymatic activities of key antioxidants enzymes including SOD, APX, CAT, and POD activities that play a crucial role in the regulation of numerous transcriptional pathways involved in oxidative stress responses. Higher non-photochemical quenching (NPQ) and QY were found in tolerant ZS758 cultivar under Cr stress, indicating that tolerant cultivar had a greater capacity to preserve PSII activity under Cr stress by enhancing heat dissipation as a photo-protective component of NPQ. Lower PSI activity and electron transfer from PSII were confirmed by lower PSI efficiency and higher donor end limitation of PSI in both rapeseed cultivars. The Cr concentration was greater in the ZD622 as compared to ZS758, which affected the mineral nutrients profile and damaged the cellular ultrastructure and related gene expression levels. However, current study suggest that cultivar ZS758 is more resistant to Cr stress than ZD622 due to improved metabolism and structural integrity and Cr stress tolerance that is linked with the increased PSII activity, NPQ, and antioxidant potential; these physiological characteristics can be exploited to select cultivars for Cr stress tolerance.

Silicon mediated heavy metal stress amelioration in fruit crops

Fruit crops are essential for human nutrition and health, yet high level of heavy metal levels in soils can degrade fruit quality. These metals accumulate in plant roots and tissues due to factors like excessive fertilizer and pesticide use, poor waste management, and unscientific agricultural practices. Such accumulation can adversely affect plant growth, physiology, and yield. Consuming fruits contaminated with toxic metals poses significant health risks, including nervous system disorders and cancer. Various strategies, such as organic manuring, biomaterials, and modified cultivation practices have been widely researched to reduce heavy metal accumulation. Recently, silicon (Si) application has emerged as a promising and cost-effective solution for addressing biological and environmental challenges in food crops. Si, which can be applied to the soil, through foliar application or a combination of both, helps reduce toxic metal concentrations in soil and plants. Despite its potential, there is currently no comprehensive review that details Si's role in mitigating heavy metal stress in fruit crops. This review aims to explore the potential of Si in reducing heavy metal-induced damage in fruit crops while enhancing growth by alleviating heavy metal toxicity.

Multifactorial optimization enables the identification of a greener method to produce (+)-nootkatone

The natural aroma compound (+)-nootkatone was obtained in selective conversions of up to 74 mol% from inexpensive (+)-valencene substrate by using a comparatively greener biocatalytic process developed based on modifications of the previously published Firmenich method. Buffer identity and concentration, pH, temperature and downstream work-up procedures were optimized to produce a crude product in which >90 % of (+)-valencene had been converted, with high chemoselectivity observed for (+)-nootkatone production. Interestingly, the biotransformation was carried out efficiently at temperatures as low as 21 ºC. Surprisingly, the best results were obtained when an acidic pH in the range of 3-6 was applied, as compared to the previously published procedure in which it appeared to be necessary to buffer the pH optimally and fixed throughout at 8.5. Furthermore, there was no need to maintain a pure oxygen atmosphere to achieve good (+)-nootkatone yields. Instead, air bubbled continuously at a low rate through the reaction mixture via a submerged glass capillary was sufficient to enable the desired lipoxygenase-catalyzed oxidation reactions to occur efficiently. No valencene epoxide side-products were detected in the organic product extract by a standard GCMS protocol. Only traces of the anticipated corresponding α- and β-nootkatol intermediates were routinely observed.

A Comprehensive Review of Lab-Scale Studies on Removing Hexavalent Chromium from Aqueous Solutions by Using Unmodified and Modified Waste Biomass as Adsorbents

Anthropogenic activities and increasing human population has led to one of the major global problems of heavy metal contamination in ecosystems and to the generation of a huge amount of waste material biomass. Hexavalent chromium [Cr(VI)] is the major contaminant introduced by various industrial effluents and activities into the ecosystem. Cr(VI) is a known mutagen and carcinogen with numerous detrimental effects on the health of humans, plants, and animals, jeopardizing the balance of ecosystems. Therefore, the remediation of such a hazardous toxic metal pollutant from the environment is necessary. Various physical and chemical methods are available for the sequestration of toxic metals. However, adsorption is recognized as a more efficient technology for Cr(VI) remediation. Adsorption by utilizing waste material biomass as adsorbents is a sustainable approach in remediating hazardous pollutants, thus serving the dual purpose of remediating Cr(VI) and exploiting waste material biomass in an eco- friendly manner. Agricultural biomass, industrial residues, forest residues, and food waste are the primary waste material biomass that could be employed, with different strategies, for the efficient sequestration of toxic Cr(VI). This review focuses on the use of diverse waste biomass, such as industrial and agricultural by-products, for the effective remediation of Cr(VI) from aqueous solutions. The review also focuses on the operational conditions that improve Cr(VI) remediation, describes the efficacy of various biomass materials and modifications, and assesses the general sustainability of these approaches to reducing Cr(VI) pollution.

Efficient removal of chromate from wastewater using a one-pot synthesis of chitosan cross-linked ceria incorporated hydrous copper oxide bio-polymeric composite

Remediating hexavalent chromium [Cr(VI)] from contaminated water systems is a significant concern due to its harmful effects on human health, aquatic life, and plants. To tackle this issue, scientists have created a chitosan cross-linked hydrous ceria incorporated cupric oxide bio-polymeric composite (CHCCO) by combining chitosan biopolymer with corresponding metal ions using glutaraldehyde as a cross-linker. The composite was characterized using advanced analytical instruments such as FTIR, p-XRD, SEM, XPS, etc. The synthesized composite (CHCCO) was then tested for its efficiency in removing Cr(VI) from synthetic Cr(VI) aqueous samples. The parameters examined included pH, material dose, contact time, concentration, temperature, and co-existing ions. The experimental data showed that the kinetics and equilibrium data fit well with the pseudo-second-order and the Freundlich isotherm models, respectively. Thermodynamic analysis demonstrated that the investigated surface adsorption process is spontaneous and endothermic. Except for the SO42- ion, no other species imparts adverse influence significantly on the reaction. The CHCCO bio-composite surfaces were refreshed using a dilute NaOH (1.0 M) solution and effectively recycled five times for Cr(VI) adsorption, indicating no significant surface activity deterioration. This study highlights the high effectiveness of CHCCO bio-polymeric composites in Cr(VI) remediation and the potential for this technology as an easy-to-use technique for environmental restoration.

Occurrence and health risk assessment of mineral composition and aflatoxin M1 in cow milk samples from different areas of Sicily, Italy

This study aimed to determine 16 mineral elements (Cd, Pb, As, Na, Mg, Al, Ca, K, Cr, Mn, Fe, Ni, Cu, Zn and Se) using inductively coupled plasma mass spectrometry (ICP-MS) and a direct mercury analyzer (DMA-80) for Hg evaluation. Aflatoxin M1 was determined by high-performance liquid chromatography with fluorescence detection (HPLC-FLD) in cow milk samples. This research considered 180 milk samples, 20 by province (Palermo, Catania, Messina), collected for a period of three years (2020-2022) to assess the potential risks for consumer, the safety status and nutritional quality related to mineral intake by consuming of milk. All samples showed a Pb concentration below the limit reported by European Regulation 915/2023. Cadmium and Hg concentrations were below the Limit Of Quantification (LOQ) in all samples analyzed. The milk samples analyzed proved to be a good source of Ca (up to 44.5 % of the dietary reference values), with well percentages also for Na (up to 7.6 %), K (up to 23.1 %) and Mg (up to 11.1 %). Regarding trace elements, the results reported that chromium requires attention; its value was always higher than 168.8 % in all samples analyzed. Levels of arsenic and lead were up to 20.2 % and up 7.1 % respectively. Aflatoxin M1 concentrations were below the limit of detection (< 0,009 mcg/kg) in all milk analyzed. Therefore, further studies are needed to safeguard consumer health, the quality of the product and to assess the state of animal health.

The genotoxicity impact of heavy metals on the Escherichia coli

In present work, the genotoxicity of Hg2+, Ag+, Cr6+, Ni2+, Pb2+, Co2+, Mn2+, Zn2+, and Cr3+ was investigated via a quantitative toxicogenomics assay, to understand the toxic mechanism of heavy metals with greater depth. Under the experimental conditions, Hg2+, Ag+, and Cr6+ showed a more serious toxic impact on the expression of functional genes (eg., oxyR, katG, grxA, osmE, emrE, dinG) than Ni2+, Pb2+, Co2+, Mn2+, Zn2+, and Cr3+, while the protein, oxidative, and membrane stress response pathways were more sensitive to the toxicity of Hg2+, Ag+, and Cr6+ than the DNA and general stress response pathways. Compared with the other kinds of heavy metals, Ni2+, Pb2+, Co2+, and Mn2+ altered the expression of functional genes (uvrY, recX, mutY, and sbmC) related to the DNA stress response pathways more seriously, while Zn2+ and Cr3+ changed the expression of the functional genes (yfjG, ydgL, ssrA, and osmC) associated with the general stress response pathway more significantly. Meanwhile, the toxicity of Ni2+, Pb2+, Co2+, and Mn2+ was slightly higher than that of Zn2+ and Cr3+ in terms of the total value of transcriptional effect level Index (TELI) by detecting the promoter activities of different functional genes. In addition, to survive the toxicity of heavy metals, the expression of multidrug efflux genes (ydgL, cyoA, emrA, and emrE) and toxicity-resistant genes (Ion, dnaJ, clpB, mutY, dnaK, rpoD, sbmC) mainly functioned.

Synergistic impacts of antibiotics and heavy metals on Hermetia illucens: Unveiling dynamics in larval gut bacterial communities and microbial metabolites

Hermetia illucens larvae showcases remarkable bioremediation capabilities for both antibiotics and heavy metal contaminants. However, the distinctions in larval intestinal microbiota arising from the single and combined effects of antibiotics and heavy metals remain poorly elucidated. In this study, we delved into the details of larval intestinal bacterial communities and microbial metabolites when exposed to single and combined contaminants of oxytetracycline (OTC) and hexavalent chromium (Cr(VI)). After conversion, single contaminant-spiked substrate showed 75.5% of OTC degradation and 95.2% of Cr(VI) reductiuon, while combined contaminant-spiked substrate exhibited 71.3% of OTC degradation and 93.4% of Cr(VI) reductiuon. Single and combined effects led to differences in intestinal bacterial communities, mainly reflected in the genera of Enterococcus, Pseudogracilibacillus, Gracilibacillus, Wohlfahrtiimonas, Sporosarcina, Lysinibacillus, and Myroide. Moreover, these effects also induced differences across various categories of microbial metabolites, which categorized into amino acid and its metabolites, benzene and substituted derivatives, carbohydrates and its metabolites, heterocyclic compounds, hormones and hormone-related compounds, nucleotide and its metabolites, and organic acid and its derivatives. In particular, the differences induced OTC was greater than that of Cr(VI), and combined effects increased the complexity of microbial metabolism compared to that of single contaminant. Correlation analysis indicated that the bacterial genera, Preudogracilibacillus, Enterococcus, Sporosarcina, Lysinibacillus, Wohlfahrtiimonas, Ignatzschineria, and Fusobacterium exhibited significant correlation with significant differential metabolites, these might be used as indicators for the resistance and bioremediation of OTC and Cr(VI) contaminants. These findings are conducive to further understanding that the metabolism of intestinal microbiota determines the resistance of Hermetia illucens to antibiotics and heavy metals.

ATF4-mediated different mode of interaction between autophagy and mTOR determines cell fate dependent on the level of ER stress induced by Cr(VI)

Hexavalent chromium [Cr(VI)] exists widely in occupational environments. The mechanistic target of rapamycin (mTOR) has been well-documented to regulate autophagy negatively. However, we found that low concentration of Cr(VI) (0.2 μM) elevated both mTOR and autophagy and promote cell survival. Conversely, high concentration of Cr(VI) (6 μM) caused cell death by inhibiting mTOR and subsequently inducing autophagy. Tunicamycin (Tm), as an Endoplasmic reticulum (ER) stress activator was used to induce mild ER stress at 0.1 μg/ml and it activated both autophagy and mTOR, which also caused cell migration in a similar manner to that observed with low concentration of Cr(VI). Severe ER stress caused by Tm (2 μg/ml) decreased mTOR, increased autophagy and then inhibited cell migration, which was the same as 6 μM Cr(VI) treatment, although Cr(VI) in high concentration inhibited ER stress. Activating transcription factor 4 (ATF4), a downstream target of ER stress, only increased under mild ER stress but decreased under severe ER stress and 6 μM Cr(VI) treatment. Chromatin immunoprecipitation (ChIP) experiment indicated that ATF4 could bind to the promoter of ATG4B and AKT1. To sum up, our data revealed that mild ER stress induced by low concentration of Cr(VI) could enhance transcriptional regulation of ATG4B and AKT1 by ATF4, which induced both autophagy and mTOR to promote cell viability.

An Update Overview on Mechanistic Data and Biomarker Levels in Cobalt and Chromium-Induced Neurodegenerative Diseases

There is increasing evidence that the imbalance of metals as cobalt (Co) and chromium (Cr) may increase the risk of development and progression of neurodegenerative diseases (NDDs). The human exposure to Co and Cr is derived mostly from industry, orthopedic implants, and polluted environments. Neurological effects of Co and Cr include memory deficit, olfactory dysfunction, spatial disorientation, motor neuron disease, and brain cancer. Mechanisms of Co and Cr neurotoxicity included DNA damage and genomic instability, epigenetic changes, mitochondrial disturbance, lipid peroxidation, oxidative stress, inflammation, and apoptosis. This paper seeks to overview the Co and Cr sources, the mechanisms by which these metals induce NDDs, and their levels in fluids of the general population and patients affected by NDDs. To this end, evidence of Co and Cr unbalance in the human body, mechanistic data, and neurological symptoms were collected using in vivo mammalian studies and human samples.

Determination of chromium species in water using diphenylcarbazide with a sequential spectrophotometric discrete robotic analyser

There is an increasing need for fast and reliable analytical methods for the determination of chemical forms of elements in environmental samples. The interest in chromium is driven by the fact that its toxicity depends on its oxidation state. Although chromium (III) is essential for mammals to maintain their metabolism of proteins, fats, and carbohydrates, chromium (VI) is toxic to humans. For chromium speciation, several costly analytical methods coupling separation methods with atomic absorption and emission spectroscopy have been developed. This article presents the online robotic discrete analyser procedure with the 1,5 diphenylcarbazide (DPC) method for the speciation of Cr (III) and Cr (VI). Cr (III) was determined by difference since it does not interfere with the reaction of Cr (VI)-DPC. Chromium (VI) and total chromium were characterised sequentially (after online oxidation of Cr (III) by Cerium (Ce (IV)). The calibration graphs were linear under experimental conditions up to 1 mg/L Cr (VI) and 2 mg/L total Cr with correlation coefficient R2, 0.9997 and 0.9999 respectively. At a signal-to-noise ratio of three, the detection limits were 0.004 mg/L Cr (VI) and 0.015 mg/L total Cr. Good agreement between the real values of certified reference materials and the chromium species content was obtained in this study. The method was precise with a percentage relative standard deviation of less than 2 for hexavalent chromium and total chromium. The t-stat demonstrates that there was no significant difference between the developed robotic discrete analyser method and the ICP-MS method. Except for effluent water, which had recoveries between 65 and 75 % in the assessment of the devised method's selectivity, the overall percentage of recoveries fell between 90 and 110 %, which was generally satisfactory. This method proved to be appropriate for its intended use.

Cardioprotective Effects of α-Asarone Against Hexavalent Chromium-Induced Oxidative Damage in Mice

Introduction

This comprehensive study investigated the therapeutic potential of α-asarone in mitigating myocardial oxidative damage, primarily induced by hexavalent chromium (Cr(VI)) exposure in mice.

Methods

In this experiment, 24 mice were divided into four groups to assess the cardioprotective role of α-asarone. The study focused on two treatment groups, receiving 25 mg and 50 mg of α-asarone, respectively. These groups were compared against a control group subjected to Cr(VI) without α-asarone treatment, and a normal control negative group. The key biochemical parameters evaluated included serum levels of Creatine Kinase-MB (CK-MB) and Troponin I, markers indicative of myocardial damage. Additionally, the levels of Malondialdehyde (MDA) were measured to assess lipid peroxidation, alongside the evaluation of key inflammatory biomarkers in cardiac tissue homogenates, such as Tumor Necrosis Factor-α (TNF-α) and Interleukin-1β (IL-1β). Results Remarkably, α-asarone treatment resulted in a significant reduction in these markers compared to the control group. The treatment also elevated the activity of cardinal antioxidant enzymes like catalase (CAT) and superoxide dismutase (SOD), and reduced the glutathione (GSH). Furthermore, a notable upregulation of Peroxisome Proliferator-Activated Receptor Gamma (PPAR-γ) in cardiac tissue homogenates was observed, highlighting a potential pathway through which α-asarone exerts its protective effects. Histopathological analysis of cardiac tissues revealed that α-asarone ameliorated the structural lesions induced by Cr(VI). The study thus provides substantial evidence that α-asarone ameliorates Cr(VI)-induced cardiotoxicity through a multifaceted approach. It enhances cardiac enzyme function, modulates free radical generation, improves antioxidant status, and mitigates histopathological damage in cardiac tissues. Given these findings, α-asarone emerges as a promising agent against Cr(VI)-induced myocardial injury.

Purpose

This study paves the way for further research into the cardioprotective properties of α-asarone and its potential application in clinical settings by specifically exploring the protective efficacy of α-asarone against Cr(VI)-induced cardiotoxicity and delineating the underlying biochemical and molecular mechanisms involved.

1- and 2-Tetrazolylacetonitrile as Versatile Ligands for Laser Ignitable Energetic Coordination Compounds

1- and 2-Tetrazolylacetonitrile (1- and 2-TAN) have been synthesized by the reaction of chloroacetonitrile with 1H-tetrazole under basic conditions. They further were reacted with sodium azide in the presence of zinc(II) chloride to form 5-((1H-tetrazol-1-yl)methyl)-1H-tetrazole (1-HTMT) and 5-((2H-tetrazol-2-yl)methyl)-1H-tetrazole (2-HTMT). The nitrogen-rich compounds have been applied as ligands for Energetic Coordination Compounds (ECCs) and show interesting coordinative behavior due to different bridging modes. The structural variability of the compounds has been proved by low-temperature X-ray analysis. The ECCs were analyzed for their sensitivities to provide information about the safety of handling and their capability to serve as primary explosives in detonator setups to replace the commonly used lead styphnate and azide. All colored ECCs were evaluated for their ignitability by laser initiation in translucent polycarbonate primer caps. In addition, the spin-crossover characteristics of [Fe(1-TAN)6](ClO4)2 were highlighted by the measurement of the temperature-dependent susceptibility curve.

Essential and Non-Essential Elements Levels in Fish Species Highly Consumed in the Middle Miranda River, Brazilian Pantanal

The present study investigated the levels of As, Ag, Al, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Pb, Se, and Zn in muscle samples of six fish species (Pygocentrus nattereri, Serrasalmus marginatus, Mylossoma duriventre, Leporinus friderici, Pimelodus argenteus, and P. pantaneiro) highly consumed by local riverine and non-resident people in middle Miranda River, southern Brazilian Pantanal. Significant differences were detected for Ba, Fe, Mn, and Zn levels among the analyzed species. Pairwise comparison detected significant differences in element levels between species with similar diets, which implies that other factors, instead of species' feeding habits, could be involved in distinct levels of element bioaccumulation. Significant correlations between body size and concentrations were found for Ba in P. nattereri (moderate positive correlation), and for Mn in M. duriventre (weak positive correlation) and P. argenteus (moderate negative correlation). Levels exceeding tolerable daily intake (TDI) were found for Pb maximum concentrations in P. nattereri, M. duriventre, L. friderici, P. argenteus, and P. pantaneiro, and for Cd maximum concentration in P. argenteus. Health risk assessment indicated considerable risk only for the worst-case scenario (calculated from maximum concentrations) for all species. Adopting a Pb monitoring program in biotic and abiotic compartments in Miranda River is strongly recommended.

The Effects of Dietary Inorganic and Organic Chromium Supplementation on Blood Metabolites, Hormones, and Mineral Composition of Blood and Internal Organs in Black Bengal goats

The present study was performed to evaluate the influence of dietary inorganic and organic chromium (Cr) supplementation on blood biochemical constituents and mineral concentrations as well as the changes in the mineral composition of internal organs of Black Bengal goats. Thirty Black Bengal kids of 3 to 5 months (5.40 ± 0.34 kg body weight) were allocated randomly to five treatment groups. The five groups were control (without added Cr in a basal diet), 1.0, 1.5 mg/kg of inorganic Cr, 1.0, and 1.5 mg/kg of organic Cr added per kilogram of feed dry matter. The duration of the experiment was 150 days during which the changes in the blood biochemical and mineral concentrations at 0, 30, 60, and 150 days were evaluated. At the end of the trial, mineral composition in the muscle, skin, and internal organs (liver, lungs, kidney, heart, spleen, and testis) were analyzed. Any blood variables were not affected at or before 60 days of Cr supplementation. Both inorganic and organic Cr supplementation lowered (P < 0.05) concentrations of blood glucose, cortisol, non-esterified fatty acids, and β-hydroxybutyric acid after 60 days of Cr supplementation. Organic Cr-supplemented groups exhibited higher (P < 0.05) blood insulin concentration and neutrophil activity compared to the control. Supplementation of Cr in either form had no substantial effect (P > 0.05) on the blood hemoglobin, total leukocyte count, total protein, albumin, globulin, immunoglobulin G, total antioxidant capacity, and liver enzymes (aminotransferases) concentration, and also blood minerals (zinc, iron, and manganese) concentration. Blood Cr and copper concentrations were increased (P < 0.05) due to both organic and inorganic Cr supplementation. Minerals (calcium, phosphorus, magnesium, iron, zinc, copper, and manganese) concentrations of internal organs of Cr-supplemented groups were mostly not affected (P > 0.05) by Cr supplementation. However, the concentrations of Cr and copper in blood and Cr in all internal organs, skin, and muscle of organic Cr-supplemented groups were higher (P < 0.05) than in those fed the basal diet. In conclusion, dietary inorganic and organic Cr supplementation, especially the organic form, after long term supplementation (> 60 days) could be beneficial in regulating blood glucose and fat metabolism and the immune status of Black Bengal goats.

Influence of Dietary Supplementation of Inorganic and Organic Chromium on Body Conformation, Carcass Traits, and Nutrient Composition in Muscle and Internal Organs of Black Bengal Goats

The effect of dietary inorganic and organic chromium (Cr) on body morphometry, carcass traits, and nutrient composition, including different minerals and fatty acids in meat and internal organs of Black Bengal goats, was studied. Thirty weaned Black Bengal kids of 3-5 months (5.40 ± 0.34 kg body weight) were assigned randomly into five groups and fed additional Cr for 150 days. The experimental diets comprised a basal diet supplemented with Cr at the rate of 0 (control; without Cr supplementation), 1.0 and 1.5 mg/kg of inorganic Cr (Cr(III)-chloride), and 1.0 and 1.5 mg/kg of organic Cr (Cr-yeast). The body morphometry such as body length, heart girth, paunch girth, loin width, leg circumference, and the carcass traits, namely, slaughter body weight, dressing percentage, hind quarter and forequarter weight, and rib eye area of goats, were not significantly (P < 0.05) changed due to inorganic and organic Cr supplementation. However, organic Cr supplementation (1.0 and 1.5 mg/kg) resulted in a reduction of breast and back fat thickness (P < 0.05) compared with the control group. The weights of internal organs including liver, lungs, spleen, kidney, testes, and heart and their weights as a percentage of slaughter weight were similar (P > 0.05) among different experimental groups. Dry matter, ether extract, and total ash concentrations of muscle and internal organs of Cr-supplemented groups were not affected (P > 0.05) by Cr supplementation. However, crude protein contents in the liver, muscle, kidney, and lungs were greater (P < 0.05) in the organic Cr groups than in the control and inorganic Cr groups. In meat (longissimus dorsi muscle), total saturated fatty acid concentration was lower (P < 0.05; 59.4% versus 55.7%) and the unsaturated fatty acid concentration was greater (P < 0.05; 40.6% versus 44.3%) including palmitoleic acid, heptadecenoic acid, elaidic acid, and arachidonic acid in the organic or inorganic Cr-supplemented groups than in the basal diet group. In conclusion, dietary supplementation of organic Cr in Black Bengal goats has no influence on the carcass traits, but may improve the meat quality with greater protein content, lean, and healthier fatty acids for human consumption.

Protective Effects of Melatonin against Carcinogen-Induced Oxidative Damage in the Thyroid

Melatonin, primarily synthesized in the pineal gland, plays a crucial role in regulating circadian rhythms and possesses significant antioxidative properties. By neutralizing free radicals and reducing oxidative stress, melatonin emerges as a promising agent for the prevention and therapy of many different disorders, including cancer. This paper reviews the relationship between the thyroid gland and melatonin, presenting experimental evidence on the protective effects of this indoleamine against oxidative damage to macromolecules in thyroid tissue caused by documented carcinogens (as classified by the International Agency for Research on Cancer, IARC) or caused by potential carcinogens. Furthermore, the possible influence on cancer therapy in humans and the overall well-being of cancer patients are discussed. The article highlights melatonin's essential role in maintaining thyroid health and its contribution to management strategies in patients with thyroid cancer and other thyroid diseases.

Growth-dependent cr(VI) reduction by Alteromonas sp. ORB2 under haloalkaline conditions: toxicity, removal mechanism and effect of heavy metals

Bacterial reduction of hexavalent chromium (VI) to chromium (III) is a sustainable bioremediation approach. However, the Cr(VI) containing wastewaters are often characterized with complex conditions such as high salt, alkaline pH and heavy metals which severely impact the growth and Cr(VI) reduction potential of microorganisms. This study investigated Cr(VI) reduction under complex haloalkaline conditions by an Alteromonas sp. ORB2 isolated from aerobic granular sludge cultivated from the seawater-microbiome. Optimum growth of Alteromonas sp. ORB2 was observed under haloalkaline conditions at 3.5-9.5% NaCl and pH 7-11. The bacterial growth in normal culture conditions (3.5% NaCl; pH 7.6) was not inhibited by 100 mg/l Cr(VI)/ As(V)/ Pb(II), 50 mg/l Cu(II) or 5 mg/l Cd(II). Near complete reduction of 100 mg/l Cr(VI) was achieved within 24 h at 3.5-7.5% NaCl and pH 8-11. Cr(VI) reduction by Alteromonas sp. ORB2 was not inhibited by 100 mg/L As(V), 100 mg/L Pb(II), 50 mg/L Cu(II) or 5 mg/L Cd(II). The bacterial cells grew in the medium with 100 mg/l Cr(VI) contained lower esterase activity and higher reactive oxygen species levels indicating toxicity and oxidative stress. In-spite of toxicity, the cells grew and reduced 100 mg/l Cr(VI) completely within 24 h. Cr(VI) removal from the medium was driven by bacterial reduction to Cr(III) which remained in the complex medium. Cr(VI) reduction was strongly linked to aerobic growth of Alteromonas sp. The Cr(VI) reductase activity of cytosolic protein fraction was pronounced by supplementing with NADPH in vitro assays. This study demonstrated a growth-dependent aerobic Cr(VI) reduction by Alteromonas sp. ORB2 under complex haloalkaline conditions akin to wastewaters.

A comparative study on chromium-induced micronuclei assessment in the peripheral blood of Hsd:ICR mice

This study investigated the genotoxic effects of chromium (Cr) in Hsd:ICR mice, considering factors such as oxidative state, apoptosis, exposure pathway, duration, pregnancy, and transplacental exposure. Genotoxicity was assessed using the erythrocytes' micronucleus (MN) assay, while apoptosis was evaluated in nucleated blood cells. The results showed that Cr(III) (CrK(SO4 )2 and CrCl3 ) did not induce any marked genotoxic damage. However, Cr(VI) (CrO3 , K2 Cr2 O7 , Na2 Cr2 O7 , and K2 CrO4 ) produced varying degrees of genotoxicity, with CrO3 being the most potent. MN frequencies increased following 24-h exposure, with a greater effect in male mice. Administering 20 mg/kg of CrO3 via gavage did not lead to significant effects compared to intraperitoneal administration. Short-term oral treatment with a daily dose of 8.5 mg/kg for 49 days elevated MN levels only on day 14 after treatment. Pregnant female mice exposed to CrO3 on day 15 of pregnancy exhibited reduced genotoxic effects compared to nonpregnant animals. However, significant increases in MN levels were found in their fetuses starting 48 h after exposure. In summary, data indicate the potential genotoxic effects of Cr, with Cr(VI) forms inducing higher genotoxicity than Cr(III). These findings indicate that gender, exposure route, and pregnancy status might influence genotoxic responses to Cr.

Understanding Cr(III) Action on Mitochondrial ATP Synthase and AMPK Efficacy: Insights from Previous Studies-a Review

Chromium supplementation has been notably recognized for its potential health benefits, especially in enhancing insulin sensitivity and managing glucose metabolism. However, recent studies have begun to shed light on additional mechanisms of action for chromium, expanding our understanding beyond its classical effects on the insulin-signaling pathway. The beta subunit of mitochondrial ATP synthase is considered a novel site for Cr(III) action, influencing physiological effects apart from insulin signaling. The physiological effects of chromium supplementation have been extensively studied, particularly in its role in anti-oxidative efficacy and glucose metabolism. However, recent advancements have prompted a re-evaluation of chromium's mechanisms of action beyond the insulin signaling pathway. The discovery of the beta subunit of mitochondrial ATP synthase as a potential target for chromium action is discussed, emphasizing its crucial role in cellular energy production and metabolic regulation. A meticulous analysis of relevant studies that were earlier carried out could shed light on the relationship between chromium supplementation and mitochondrial ATP synthase. This review categorizes studies based on their primary investigations, encompassing areas such as muscle protein synthesis, glucose and lipid metabolism, and antioxidant properties. Findings from these studies are scrutinized to distinguish patterns aligning with the new hypothesis. Central to this exploration is the presentation of studies highlighting the physiological effects of chromium that extend beyond the insulin signaling pathway. Evaluating the various independent mechanisms of action that chromium impacts cellular energy metabolism and overall metabolic balance has become more important. In conclusion, this review is a paradigm shift in understanding chromium supplementation, paving the way for future investigations that leverage the intricate interplay between chromium and mitochondrial ATP synthase.

Health risk assessments of heavy metals and trace elements exposure in the breast milk of lactating mothers in the Northeastern Iran

Mother's breast milk is a natural and complete food for infants but can be a main source of exposure to toxic pollutants. These pollutants can negatively affect the health of the infant. Therefore, conducting biomonitoring surveys is essential to evaluate such health effects in toxicological research. This study aimed to estimate the probable health risks for infants exposed to essential and non-essential trace elements through breast milk ingestion. This descriptive-analytical, cross-sectional study was performed on 90 breastfeeding mothers referred to the health centers in Mashhad, Iran in January 2021. The health risk assessments (carcinogenic and non-carcinogenic risk) were estimated using chronic daily intake (CDI), hazard quotient (HQ), hazard index (HI), and lifetime carcinogenic risk (CR), which were recommended by the US Environmental Protection Agency (US EPA). The results of the HQ values of trace elements through ingestion exposure for arsenic (90%), copper (90%), zinc (40%), and iron (10%) exceeded the threshold of HQ, and arsenic (66.59%), copper (16.91%), and zinc (9.68%) and iron (4.57%) had the highest contribution to increasing the HI index. The average value of CR was 5. 08 × 10-3. Chromium and iron showed significant relationships (P<0.05) with education level and disease background in this study, and the concentration of chromium, iron, and zinc in the breast milk samples significantly changed during lactation stages (P<0.05). Overall, the risk of carcinogenicity through exposure to breast milk for infants was higher than the safety level of US EPA risk. Therefore, there could be a potential health risk of trace elements, particularly arsenic, copper, and zinc for infants in Mashhad, Iran through the consumption of mothers' breast milk. More efforts are required to control and reduce routes of receiving trace elements in breastfeeding mothers by the competent authorities.

Human Health Effects of Oral Exposure to Chromium: A Systematic Review of the Epidemiological Evidence

The toxicity and carcinogenicity of hexavalent chromium via the inhalation route is well established. However, a scientific debate has arisen about the potential effects of oral exposure to chromium on human health. Epidemiological studies evaluating the connection between ingested chromium and adverse health effects on the general population are limited. In recent years, a wealth of biomonitoring studies has emerged evaluating the associations between chromium levels in body fluids and tissues and health outcomes. This systematic review brings together epidemiological and biomonitoring evidence published over the past decade on the health effects of the general population related to oral exposure to chromium. In total, 65 studies were reviewed. There appears to be an inverse association between prenatal chromium exposure and normal fetal development. In adults, parameters of oxidative stress and biochemical alterations increase in response to chromium exposure, while effects on normal renal function are conflicting. Risks of urothelial carcinomas cannot be overlooked. However, findings regarding internal chromium concentrations and abnormalities in various tissues and systems are, in most cases, controversial. Environmental monitoring together with large cohort studies and biomonitoring with multiple biomarkers could fill the scientific gap.

Evidence for chromium crosses blood brain barrier from the hypothalamus in chromium mice model

It has been shown that exposure to hexavalent Chromium, Cr (Ⅵ), via nasal cavity can have neurotoxicological effects and induces behavioral impairment due to the fact that blood brain barrier (BBB) does not cover olfactory bulb. But whether Cr (Ⅵ) can cross the BBB and have a toxicological effects in central nervous system (CNS) remains unclear. Therefore, we investigated the effects of Cr (Ⅵ) on mice treated with different concentrations and exposure time (14 days and 28 days) of Cr (Ⅵ) via intraperitoneal injection. Results revealed that Cr accumulated in hypothalamus (HY) in a timely dependent manner. Much more severer neuropathologies was observed in the group of mice exposed to Cr (Ⅵ) for 28 days than that for 14 days. Gliosis, neuronal morphological abnormalities, synaptic degeneration, BBB disruption and neuronal number loss were observed in HY. In terms of mechanism, the Nrf2 related antioxidant stress signaling dysfunction and activated NF-κB related inflammatory pathway were observed in HY of Cr (Ⅵ) intoxication mice. And these neuropathologies and signaling defects appeared in a timely dependent manner. Taking together, we proved that Cr (Ⅵ) can enter HY due to weaker BBB in HY and HY is the most vulnerable CNS region to Cr (Ⅵ) exposure. The concentration of Cr in HY increased along with time. The accumulated Cr in HY can cause BBB disruption, neuronal morphological abnormalities, synaptic degeneration and gliosis through Nrf2 and NF-κB signaling pathway. This finding improves our understanding of the neurological dysfunctions observed in individuals who have occupational exposure to Cr (Ⅵ), and provided potential therapeutic targets to treat neurotoxicological pathologies induced by Cr (Ⅵ).

May 1,3,5-Triazine derivatives be the future of leather tanning? A critical review

Leather is produced by a multi-step process among which the tanning phase is the most relevant, transforming animal skin collagen into a stable, non-putrescible material used to produce a variety of different goods, for the footwear, automotive, garments, and sports industry. Most of the leather produced today is tanned with chromium (III) salts or alternatively with aldehydes or synthetic tannins, generating high environmental concern. Over the years, high exhaustion tanning systems have been developed to reduce the environmental impact of chromium salts, which nevertheless do not avoid the use of metals. Chrome-free alternatives such as aldehydes and phenol based synthetic tannins, are suffering from Reach restrictions due to their toxicity. Thus, the need for environmentally benign and economically sustainable tanning agents is increasingly urgent. In this review, the synthesis, use and tanning mechanism of a new class of tanning agents, 1,3,5-triazines derivatives, have been reported together with organoleptic, physical mechanical characteristics of tanned leather produced. Additionally environmental performance and economic data available for 1,3,5-triazines have been compared with those of a standard basic chromium sulphate tanning process, evidencing the high potentiality for sustainable, metal, aldehyde, and phenol free leather manufacturing.

Silicon a key player to mitigate chromium toxicity in plants: Mechanisms and future prospective

Chromium is a serious heavy metal (HM) and its concentration in plant-soil interface is soaring due to anthropogenic activities, unregulated disposals, and lack of efficient treatments. High concentration of Cr is toxic to ecosystems and human health. Cr stress also diminishes the plant performance by changing the plant's vegetative and reproductive development that ultimately affects sustainable crop production. Silicon (Si) is the second-most prevalent element in the crust of the planet, and has demonstrated a remarkable potential to minimize the HM toxicity. Amending soils with Si mitigates adverse effects of Cr by improving plant physiological, biochemical, and molecular functioning and ensuring better Cr immobilization, compartmentation, and co-precipitation. However, there is no comprehensive review on the role of Si to mitigate Cr toxicity in plants. Thus, in this present review; the discussion has been carried on; 1) the source of Cr, 2) underlying mechanisms of Cr uptake by plants, 3) how Si affects the plant functioning to reduce Cr toxicity, 4) how Si can cause immobilization, compartmentation, and co-precipitation 5) strategies to improve Si accumulation in plants to counter Cr toxicity. We also discussed the knowledge gaps and future research needs. The present review reports up-to-date knowledge about the role of Si to mitigate Cr toxicity and it will help to get better crop productivity in Cr-contaminated soils. The findings of the current review will educate the readers on Si functions in reducing Cr toxicity and will offer new ideas to develop Cr tolerance in plants through the use of Si.

Effects of selenium on biogeochemical cycles of cadmium in rice from flooded paddy soil systems in the alluvial Indus Valley of Pakistan

This study delves into the pollution status, assesses the effects of Se on Cd biogeochemical pathways, and explores their interactions in nutrient-rich paddy soil-rice ecosystems through 500 soil-rice samples in Pakistan. The results showed that 99.6 % and 12.8 % of soil samples exceeded the World Health Organization (WHO) allowable Se and Cd levels (7 and 0.35 mg/kg). In comparison, 23 % and 6 % of the grain samples exceeded WHO's allowable Se and Cd levels (0.3 and 0.2 mg/kg), respectively. Geographically Weighted Regression (GWR) model results further revealed spatial nonstationarity, confirming diverse associations between dependent variables (Se and Cd in rice grain) and independent variables from paddy soil and plant tissues (root and shoot), such as Soil Organic Matter (SOM), pH, Se, and Cd concentrations. High Se:Cd molar ratios (>1) and a negative correlation (r = -0.16, p < 0.01) between the Cd translocation factor (Cd in rice grain/Cd in root) and Se in roots suggest that increased root Se levels inhibit the transfer of Cd from roots to grains. The inverse correlation between Se and Cd in paddy grains was further characterized as Se deficiency, no risk, high Cd risk, Se risk, Cd risk, and Se-Cd co-exposure risk. There was no apparent risk for human co-consumption in 42.6 % of grain samples with moderate Se and low Cd. The remaining categories indicate differing degrees of risk. In the study area, 31 % and 20 % of grain samples with low Se and Cd indicate Se deficiency and risk, respectively. High Se and low Cd levels in rice samples suggest a potential hazard for severe Se exposure due to frequent rice consumption. This study not only systematically evaluates the pollution status of paddy-soil systems in Pakistan but also provides a reference to thoroughly contemplate the development of a scientific approach for evaluating human risks and the potential dangers associated with paddy soils and rice, specifically in regions characterized by low Se and low Cd concentrations, as well as those with moderate Se and high Cd concentrations. SYNOPSIS: This study is significant for understanding the effects of Se on Cd geochemical cycles and their interactions in paddy soil systems in Pakistan.

Metabolic mechanism of Cr(VI) pollution remediation by Alicycliphilus denitrificans Ylb10

Cr(VI) is a well-known toxic pollutant and its remediation has attracted great attention. It is important to continuously discover and explore new high-efficiency Cr(VI) reducing bacteria to further improve the efficiency of Cr(VI) pollution remediation. In this paper, metabolic mechanism of Cr(VI) reduction in a new highly efficient Cr(VI) reducing bacterium, Alicycliphilus denitrificans Ylb10, was investigated. The results showed that Ylb10 could tolerate and completely reduce 450 mg/L Cr(VI). Cr(VI) can be reduced in the intracellular compartment, membrane and the extracellular compartment, with the plasma membrane being the main active site for Cr(VI) reduction. With the addition of NADH, the reduction efficiency of cell membrane components for Cr(VI) increased 2.3-fold. The omics data analysis showed that sulfite reductase CysJ, thiosulfate dehydrogenase TsdA, nitrite reductase NrfA, nitric oxide reductase NorB, and quinone oxidoreductase ChrR play important roles in the reduction of Cr(VI), in the intracellular, and the extracellular compartment, and the membrane of Ylb10, and therefore Cr(VI) was reduced by the combined action of several reductases at these three locations.

Ethnobotanical, ecological and health risk assessment of some selected wild medicinal plants collected along mafic and Ultra Mafic rocks of Northwest Pakistan

The current study investigated wild plant resources and health risk assessment along with northern Pakistan's mafic and ultramafic regions. Ethnobotanical data was collected through field visits and semi-structured questionnaire surveys conducted from local inhabitants and healers. Six potentially toxic elements (PTEs) such as lead (Pb), cadmium (Cd), nickel (Ni), chromium (Cr), manganese (Mn), and zinc (Zn) were extracted with acids and analyzed using atomic absorption spectrophotometer (AAS, Perkin Elmer-7000) in nine selected wild medicinal plants. Contamination factor (CF), pollution load index (PLI), estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI) were used to determine the health risk assessment of the studied medicinal plants. The results showed that the selected medicinal plants were used for the treatments of cough, joint swelling, cardiovascular disorders, toothaches, diabetes, and skin pimples by the local inhabitants due to their low-cost and easy accessibility. The concentrations of Pb (3.4-53 mg kg-1), Cd (0.03-0.39 mg kg-1), Ni (17.5-82 mg kg-1), Cr (29-315 mg kg-1), Mn (20-142 mg kg-1), and Zn (7.4-64 mg kg-1) in the studied medicinal plants were found above the safe limits (except Zn) set by WHO/FAO/USEPA (1984/2010). The Pb contamination factor was significantly (p < 0.05) higher in A. modesta (7.84) and D. viscosa (6.81), and Cd contamination factor was significantly higher in C. officinalis (26.67), followed by A. modesta (8.0) mg kg-1. Based on PTE concentrations, the studied plants are considered not suitable for human consumption purposes. Pollution load index values for A. modesta, A. barbadensis, A. caudatus, A. indica, C. procera (2.93), D. viscosa (2.79), and C. officinalis (2.83), R. hastatus (3.12), and Z. armatum were observed as 1.00, 2.80, 2.29, 2.29, 2.93, 2.79, 2.83, 3.12 and 2.19, respectively. Hazard index values were in order of R. hastatus (1.32 × 10-1) ˃ C. procera (1.21 × 10-1) ˃ D. viscosa (1.10 × 10-1) ˃ A. caudatus (9.11 × 10-2) ˃ A. barbadensis (8.66 × 10-2) ˃ Z. armatum (7.99 × 10-2) ˃ A. indica (6.87 × 10-2) ˃ A. modesta (5.6 × 10-2) ˃ C. officinalis (5.42 × 10-2). The health risk index values suggested that consumption of these plants individually or in combination would cause severe health problems in the consumers. Pearson's correlation results showed a significant correlation (p ≤ 0.001) between Zn and Mn in the studied medicinal plants. The current study suggests that wild medicinal plants should be adequately addressed for PTEs and other carcinogenic pollutants before their uses in the study area. Open dumping of mining waste should be banned and eco-friendly technology like organic amendments application should be used to mitigate PTEs in the study area.

Effect of long-term treatment with trivalent chromium on erythropoietin production in HepG2 cells

Trivalent chromium (Cr(III)) is sometimes taken as a long-term supplement, but its effectiveness is unclear. Recently, Cr(III) reportedly modulates peroxisome proliferator-activated receptor gamma (PPARγ) expression. Our previous study reported that increased PPARγ after 24 h Cr(III) treatment promoted erythropoietin (EPO) production in HepG2 cells. In the current study, we analyzed 4-week Cr(III) treatment effects on PPARγ and EPO production in HepG2 cells. Long-term Cr(III) treatment resulted in significantly elevated mRNA expression levels of PPARγ and EPO compared to controls. Additionally, treatment with a PPARγ inhibitor suppressed EPO mRNA expression. Increased EPO mRNA expression due to stimulation with hypoxia or cobalt was unaffected by long-term Cr(III) treatment. Administration of lipopolysaccharide and pyocyanin which causes oxidative stress, promoted EPO production, but this effect was attenuated in cells treated with Cr(III). Long-term Cr(III) treatment increased hypoxia inducible factor (HIF)-1α and 2α mRNA expression and protein levels. Increased PPARγ, induced by long-term Cr(III) treatment, suppressed sirtuin1 (SIRT1) mRNA expression and increased EPO mRNA expression, suggesting that increased PPARγ attenuated the suppressive effect of SIRT1 on HIF. These results suggest that the sustained increase in PPARγ during long-term Cr(III) treatment maintains increased EPO production through a mechanism different from that observed under hypoxia.

The visible-light-driven photocatalytic reduction of Cr6+ using BiVO4: assessing the effect of Au deposition and the reaction parameters

In this work, fern-leaf-like BiVO4 was used to photocatalytically reduce Cr6+ in water. Nanosized BiVO4 displayed bandgap energy and specific surface area of 2.49 eV and 5.65 m2 g-1, respectively. Metallic Au nanoparticles were deposited on the BiVO4 to increase the photocatalytic performance. To optimize the reaction conditions, the sacrificial agents methanol, ethanol, formic acid, dimethyl sulfoxide, and KI were tested, while different catalyst dosages and Au loadings were assessed. The best sacrificial agent was formic acid, which was used at an optimal concentration of 0.01 mol L-1. The complete removal of Cr6+ was attained after 90 min of visible light irradiation using a catalyst dosage of 1.5 g L-1. Depositing metallic Au nanoparticles barely improved the photocatalytic performance, thus unmodified BiVO4 was used to remove Cr6+ in tap water. The matrix effect slowed the photocatalytic process, and the complete removal of Cr6+ was achieved in 120 min. Cr3+ and Cr6+ species were precipitated on the catalyst surface at the end of the photocatalytic process; still, BiVO4 displayed high stability after three reaction cycles.

Effects of hexavalent chromium on mitochondria and their implications in carcinogenesis

Hexavalent chromium (Cr(VI)) is a well-known occupational and environmental human carcinogen. The cellular effect of Cr(VI) is complex and often nonspecific due to its ability to modulate multiple cellular targets. The toxicity of Cr(VI) is strongly linked to the generation of reactive oxygen species (ROS) during its reduction process. ROS can cause oxidation of cellular macromolecules, such as proteins, lipids, and DNA, thereby altering their functions. A major genotoxic effect of Cr(VI) that contributes to carcinogenesis is the formation of DNA adducts, which can lead to DNA damage. Modulations of cellular signaling pathways and epigenetics may also contribute to the carcinogenic effects of Cr(VI). Cr(VI) has a major impact on many aspects of mitochondrial biology, including oxidative phosphorylation, mitophagy, and mitochondrial biogenesis. These effects have the potential to alter the trajectory of Cr(VI)-induced carcinogenic process. This perspective article summarizes current understandings of the effect of Cr(VI) on mitochondria and discusses the future directions of research in this area, particularly with regard to carcinogenesis.

Toxicity factors to assess the ecological risk for soil microbial communities

The toxicity factor (TF), a critical parameter within the potential ecological risk index (RI), is determined without accounting for microbial factors. It is considerable uncertainty exists concerning its validity for quantitatively assessing the influence of metal(loid)s on microorganisms. To evaluate the suitability of TF, we constructed microcosm experiments with varying RI levels (RI = 100, 200, 300, 500, and 700) by externally adding zinc (Zn), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), cadmium (Cd), and mercury (Hg) to uncontaminated soil (CK). Quantitative real-time PCR (qPCR) and high-throughput sequencing techniques were employed to measure the abundance and community of bacteria and fungi, and high-throughput qPCR was utilised to quantify functional genes associated with CNPS cycles. The results demonstrated that microbial diversity and function exhibited significant alterations (p < 0.05) in response to increasing RI levels, and the influences on microbial community structure, enzyme activity, and functional gene abundances were different due to the types of metal(loid)s treatments. At the same RI level, significant differences (p < 0.05) were discerned in microbial diversity and function across metal(loid) treatments, and these differences became more pronounced (p < 0.001) at higher levels. These findings suggest that TF may not be suitable for the quantitative assessment of microbial ecological risk. Therefore, we adjusted the TF by following three steps (1) determining the adjustment criteria, (2) deriving the initial TF, and (3) adjusting and optimizing the TF. Ultimately, the optimal adjusted TF was established as Zn = 1.5, Cr = 4.5, Cu = 6, Pb = 4.5, Ni = 5, Cd = 22, and Hg = 34. Our results provide a new reference for quantitatively assessing the ecological risks caused by metal(loid)s to microorganisms.

Bridging Component Strategy in Phosphomolybdate-Based Sensors for Electrochemical Determination of Trace Cr(VI)

Rapid and sensitive electrochemical determination of trace carcinogenic Cr(VI) pollutants remains an urgent and important task, which requires the development of active sensing materials. Herein, four cases of reduced phosphomolybdates with formulas of the (H2bib)3[Zn(H2PO4)]2{Mn[P4Mo6O31H7]2}·6H2O (1), (H2bib)2[Na(H2O)]2[Mn(H2O)]2{Mn[P4Mo6O31H6]2}·5H2O (2), (H2bib)3[Mo2(μ2-O)2(H2O)4]2{Ni[P4Mo6O31H2]2}·4H2O (3), and (H2bib)2{Ni[P4Mo6O31H9]2}·9H2O (4) (bib = 4,4'-bis(1-imidazolyl)-biphenyl) were hydrothermally synthesized under the guidance of a bridging component strategy, which function as effective electrochemical sensors to detect trace Cr(VI). The difference of hybrids 1-4 is in the inorganic moiety, in which the reduced phosphomolybdates {M[P4MoV6O31]2} (M{P4Mo6}2) exhibited different arrangements bridged by different cationic components ({Zn(H2PO4)} subunit for 1, [Mn2(H2O)2]4+ dimer for 2, and [MoV2(μ2-O)2(H2O)4]6+ for 3). As a result, hybrids 1 and 3 display noticeable Cr(VI) detection activity with low detection limits of 14.3 nM (1.48 ppb) for 1 and 6.61 nM (0.69 ppb) for 3 and high sensitivities of 97.3 and 95.3 μA·mM-1, respectively, which are much beyond the World Health Organization's detection threshold (0.05 ppm) and superior to those of the contrast samples (inorganic Mn{P4Mo6}2 salt and hybrid 4), even the most reported noble-metal catalysts. This work supplies a prospective pathway to build effective electrochemical sensors based on phosphomolybdates for environmental pollutant treatment.