Chromium VI and stomach cancer: a meta-analysis of the current epidemiological evidence

Tag-free fluorometric aptasensor for detection of chromium(VI) in foods via SYBR Green I signal amplification and aptamer structure transition

BACKGROUND

In response to growing concerns regarding heavy metal contamination in food, particularly chromium (Cr)(VI) contamination, this study presented a simple, sensitive and practical method for Cr(VI) detection.

RESULTS

A magnetic separation-based capture-exponential enrichment ligand system evolution (SELEX) method was used to identify and characterize DNA aptamers with a high affinity for Cr(VI). An aptamer, Cr-15, with a dissociation constant (Kd) of 4.42 ± 0.44 μmol L-1 was obtained after only eight rounds of selection. Further innovative methods combining molecular docking, dynamic simulation and thermodynamic analysis revealed that CrO4 2- could bind to the 19th and 20th guanine bases of Cr-15 via hydrogen bonds. Crucially, a label-free fluorometric aptasensor based on SYBR Green I was successfully constructed to detect CrO4 2-, achieving a linear detection range of 60-300 nmol L-1 with a lower limit of detection of 44.31 nmol L-1. Additionally, this aptasensor was able to quantitatively detect CrO4 2- in grapes and broccoli within 40 min, with spike recovery rates ranging from 89.22% to 108.05%. The designed fluorometric aptasensor exhibited high selectivity and could detect CrO4 2- in real samples without sample processing or target pre-enrichment.

CONCLUSION

The aptasensor demonstrated its potential as a reliable tool for monitoring Cr(VI) contamination in fruit and vegetable products. © 2024 Society of Chemical Industry.

Insights into the effects of chronic combined chromium-nickel exposure on colon damage in mice through transcriptomic analysis and in vitro gastrointestinal digestion assay

Heavy metals interact with each other in a coexisting manner to produce complex combined toxicity to organisms. At present, the toxic effects of chronic co-exposure to heavy metals hexavalent chromium [Cr(VI)] and divalent nickel [Ni(II)] on organisms are seldom studied and the related mechanisms are poorly understood. In this study, we explored the mechanism of the colon injury in mice caused by chronic exposure to Cr or/and Ni. The results showed that, compared with the control group, Cr or/and Ni chronic exposure affected the body weight of mice, and led to infiltration of inflammatory cells in the colon, decreased the number of goblet cells, fusion of intracellular mucus particles and damaged cell structure of intestinal epithelial. In the Cr or/and Ni exposure group, the activity of nitric oxide synthase (iNOS) increased, the expression levels of MUC2 were significantly down-regulated, and those of ZO-1 and Occludin were significantly up-regulated. Interestingly, factorial analysis revealed an interaction between Cr and Ni, which was manifested as antagonistic effects on iNOS activity, ZO-1 and MUC2 mRNA expression levels. Transcriptome sequencing further revealed that the expression of genes-related to inflammation, intestinal mucus and tight junctions changed obviously. Moreover, the relative contents of Cr(VI) and Ni(II) in the Cr, Ni and Cr+Ni groups all changed with in-vitro gastrointestinal （IVG）digestion, especially in the Cr+Ni group. Our results indicated that the chronic exposure to Cr or/and Ni can lead to damage to the mice colon, and the relative content changes of Cr(VI) and Ni(II) might be the main reason for the antagonistic effect of Cr+Ni exposure on the colon damage.

Small-Molecule Fluorescent Probes for Binding- and Activity-Based Sensing of Redox-Active Biological Metals

Although transition metals constitute less than 0.1% of the total mass within a human body, they have a substantial impact on fundamental biological processes across all kingdoms of life. Indeed, these nutrients play crucial roles in the physiological functions of enzymes, with the redox properties of many of these metals being essential to their activity. At the same time, imbalances in transition metal pools can be detrimental to health. Modern analytical techniques are helping to illuminate the workings of metal homeostasis at a molecular and atomic level, their spatial localization in real time, and the implications of metal dysregulation in disease pathogenesis. Fluorescence microscopy has proven to be one of the most promising non-invasive methods for studying metal pools in biological samples. The accuracy and sensitivity of bioimaging experiments are predominantly determined by the fluorescent metal-responsive sensor, highlighting the importance of rational probe design for such measurements. This review covers activity- and binding-based fluorescent metal sensors that have been applied to cellular studies. We focus on the essential redox-active metals: iron, copper, manganese, cobalt, chromium, and nickel. We aim to encourage further targeted efforts in developing innovative approaches to understanding the biological chemistry of redox-active metals.

Microbiological Analysis and Content of Heavy Metals in Different Candies, Chocolates, and Their Wrappers in Bangladesh

Present study investigates 39 brands of candies, chocolate, and litchis, purchased from Dhaka City, Bangladesh, for their moisture content, sulphated ash value, heavy metal, and bacterial contamination. All the brands showed moisture content (0.64%-4.775%) within the BSTI range, but sulphated ash values (18.80%-25.72%) were beyond the accepted value. Pb, Cd, Ni, and Cr ranged from 0.24-2.40 μg/g, 0.071-0.44 μg/g, 0.38-48.10 μg/g, and 0.50-12.79 μg/g, respectively, in the tested brands. Most of the brands contained Pb and Cd beyond the acceptable limits of WHO/FDA. Pb (2.24-2586.75 μg/g) was found in high concentration in the packaging of most brands, and Ni and Cd ranged from 2.10-108.05 μg/g and 1.68-45 μg/g, respectively. Bacterial presence was found in 15 brands, and 4 of them had a total aerobic bacterial count of >1 log CFU/g. Consumption of such contaminated confectionaries holds significant public health risks, specially in children, and demands necessary precautionary steps.

Assessment of drinking water quality and health risk using water quality index and multiple computational models: a case study of Yangtze River in suburban areas of Wuhan, central China, from 2016 to 2021

Water quality, increasingly recognized for its significant impact on health, is garnering heightened attention. Previous studies were limited by the number of water quality indicators and the duration of analysis. This study assessed the drinking water quality and its associated health risk in suburban areas of Wuhan, a city in central China, from 2016 to 2021. We collected 368 finished water samples and 1090 tap water samples and tested these for 37 different indicators. The water quality was evaluated using the water quality index, with trends over time analyzed via the Mann-Kendall test. Furthermore, an artificial neural network model was employed for future water quality prediction. Our findings indicated that the water quality in rural Wuhan was generally good and had an improvement from 2016 to 2021. The qualification and excellent rates were 98.91% and 86.81% for finished water, and 97.89% and 78.07% for tap water, respectively. The drinking water quality was predicted to maintain satisfactory in 2022 and 2023. Additionally, principal component analysis revealed that the primary sanitary issues in the water were poor sensory properties, elevated metal contents, high levels of dissolved solids, and microbial contamination. These issues were likely attributable to domestic and industrial waste discharge and aging water pipelines. The health risks associated with the long-term consumption of this water have been steadily decreasing over the years, underscoring the effectiveness of Wuhan's ongoing water management efforts.

Hexavalent Chromium Induces Neurotoxicity by Triggering Mitochondrial Dysfunction and ROS-Mediated Signals

Hexavalent chromium (Cr (VI)), one of the most detrimental pollutants, has been ubiquitously present in the environment and causes serious toxicity to humans, such as hepatotoxicity, nephrotoxicity, pulmonary toxicity, and cardiotoxicity. However, Cr (VI)-induced neurotoxicity in primary neuron level has not been well explored yet. Herein, potassium dichromate (K2Cr2O7) was employed to examine the neurotoxicity of Cr (VI) in rat primary hippocampal neurons. MTT test was used to examine the neural viability. Mitochondrial dysfunction was assessed by the JC-1 probe and Mito-Tracker probe. DCFH-DA and Mito-SOX Red were utilized to evaluate the oxidative status. Bcl-2 family and MAPKs expression were investigated using Western blotting. The results demonstrated that Cr (VI) treatment dose- and time-dependently inhibited neural viability. Mechanism investigation found that Cr (VI) treatment causes mitochondrial dysfunction by affecting Bcl-2 family expression. Moreover, Cr (VI) treatment also induces intracellular reactive oxygen species (ROS) generation, DNA damage, and MAPKs activation in neurons. However, inhibition of ROS by glutathione (GSH) effectually balanced Bcl-2 family expression, attenuated DNA damage and the MAPKs activation, and eventually improved neural viability neurons. Collectively, these above results above suggest that Cr (VI) causes significant neurotoxicity by triggering mitochondrial dysfunction, ROS-mediated oxidative damage and MAKPs activation.

The role of metal ions in the occurrence, progression, drug resistance, and biological characteristics of gastric cancer

Metal ions exert pivotal functions within the human body, encompassing essential roles in upholding cell structure, gene expression regulation, and catalytic enzyme activity. Additionally, they significantly influence various pathways implicated in divergent mechanisms of cell death. Among the prevailing malignant tumors of the digestive tract worldwide, gastric cancer stands prominent, exhibiting persistent high mortality rates. A compelling body of evidence reveals conspicuous ion irregularities in tumor tissues, encompassing gastric cancer. Notably, metal ions have been observed to elicit distinct contributions to the progression, drug resistance, and biological attributes of gastric cancer. This review consolidates pertinent literature on the involvement of metal ions in the etiology and advancement of gastric cancer. Particular attention is directed towards metal ions, namely, Na, K, Mg, Ca, Fe, Cu, Zn, and Mn, elucidating their roles in the initiation and progression of gastric cancer, cellular demise processes, drug resistance phenomena, and therapeutic approaches.

The impact of toxic metal bioaccumulation on colorectal cancer: Unravelling the unexplored connection

Colorectal cancer is a major public health concern, with increasing incidence and mortality rates worldwide. Environmental factors, including exposure to toxic metals, such as lead, chromium, cadmium, aluminium, copper, arsenic and mercury, have been suggested to play a significant role in the development and progression of this neoplasia. In particular, the bioaccumulation of toxic metals can play a significant role in colorectal cancer by regulating biological phenomenon associated to both cancer occurrence and progression, such as cell death and proliferation. Also, frequently these metals can induce DNA mutations in well-known oncogenes. This review provides a critical analysis of the current evidence, highlighting the need for further research to fully grasp the complex interplay between toxic metal bioaccumulation and colorectal cancer. Understanding the contribution of toxic metals to colorectal cancer occurrence and progression is essential for the development of targeted preventive strategies and social interventions, with the ultimate goal of reducing the burden of this disease.

Biogeochemical behaviour and toxicology of chromium in the soil-water-human nexus: A review

Chromium (Cr) affects human health if it accumulates in organs to elevated concentrations. The toxicity risk of Cr in the ecosphere depends upon the dominant Cr species and their bioavailability in the lithosphere, hydrosphere, and biosphere. However, the soil-water-human nexus that controls the biogeochemical behaviour of Cr and its potential toxicity is not fully understood. This paper synthesizes information on different dimensions of Cr ecotoxicological hazards in the soil and water and their subsequent effects on human health. The various routes of environmental exposure of Cr to humans and other organisms are also discussed. Human exposure to Cr(VI) causes both carcinogenic and non-carcinogenic health effects via complicated reactions that include oxidative stress, chromosomal and DNA damage, and mutagenesis. Chromium (VI) inhalation can cause lung cancer; however, incidences of other types of cancer following Cr(VI) exposure are low but probable. The non-carcinogenic health consequences of Cr(VI) exposure are primarily respiratory and cutaneous. Research on the biogeochemical behaviour of Cr and its toxicological hazards on human and other biological routes is therefore urgently needed to develop a holistic approach to understanding the soil-water-human nexus that controls the toxicological hazards of Cr and its detoxification.

Synthesis and application of quantum dots in detection of environmental contaminants in food: A comprehensive review

Environmental pollutants can accumulate in the human body through the food chain, which may seriously impact human health. Therefore, it is of vital importance to develop quick, simple, accurate and sensitive (respond quickly) technologies to evaluate the concentration of environmental pollutants in food. Quantum dots (QDs)-based fluorescence detection methods have great potential to overcome the shortcomings of traditional detection methods, such as long detection time, cumbersome detection procedures, and low sensitivity. This paper reviews the types and synthesis methods of QDs with a focus on green synthesis and the research progress on rapid detection of environmental pollutants (e.g., heavy metals, pesticides, and antibiotics) in food. Metal-based QDs, carbon-based QDs, and "top-down" and "bottom-up" synthesis methods are discussed in detail. In addition, research progress of QDs in detecting different environmental pollutants in food is discussed, especially, the practical application of these methods is analyzed. Finally, current challenges and future research directions of QDs-based detection technologies are critically discussed. Hydrothermal synthesis of carbon-based QDs with low toxicity from natural materials has a promising future. Research is needed on green synthesis of QDs, direct detection without pre-processing, and simultaneous detection of multiple contaminants. Finally, how to keep the mobile sensor stable, sensitive and easy to store is a hot topic in the future.

Hexavalent chromium causes centrosome amplification by inhibiting the binding between TMOD2 and NPM2

BACKGROUND

Hexavalent chromium can promote centrosome amplification (CA) as well as tumorigenesis. Since CA can lead to tumorigenesis, it is plausible that the chromium promotes the development of cancer via CA. In the present study, we investigated the signaling pathways of the chromium-induced CA.

RESULTS

Our results showed that sub-toxic concentration of chromium was able to cause CA in HCT116 cells, and decrease the expression of TMOD2 and NPM2. Furthermore, TMOD2 and NPM2 interacted to each other via their C-terminal and the N-terminal, respectively, which was inhibited by the chromium. Overexpression of TMOD2 and NPM2 increased their binding and significantly attenuated the CA. Moreover, TMOD2 and NPM2 were co-localized with the centrosomes. The chromium inhibited the centrosomeal localization of NPM2, which was reversed by the overexpression of TMOD2, C-terminal of TMOD2, but not the N-terminal of NPM2.

CONCLUSION

Our results suggest that the chromium induces CA via inhibiting the binding between TMOD2 and NPM2 as well as the dissociation of NPM2 from centrosomes.

AVAILABILITY OF DATA AND MATERIALS

The data and materials are available from the corresponding authors.

HBM4EU chromates study - the measurement of hexavalent and trivalent chromium in exhaled breath condensate samples from occupationally exposed workers across Europe

The aim of this study was to investigate the practicability of exhaled breath condensate (EBC) as a biological matrix to detect and measure hexavalent chromium (Cr(VI)) and trivalent chromium (Cr(III)) in workers occupationally exposed to Cr(VI). EBC samples were collected from workers in France, Finland, Italy, The Netherlands and the United Kingdom from three different target activities: chrome platers, stainless steel welders and surface treatment workers. Pre and post working week EBC samples were collected from 177 exposed workers and 98 unexposed workers (control group). Hyphenated chromatography systems with inductively coupled plasma - mass spectrometry (ICP-MS) were for the analysis. The results showed that the occupationally exposed workers had significantly higher levels of Cr(VI) and Cr(III) than the control group. Chrome platers exhibited the highest Cr(VI) levels in their EBC samples, with a significant increase from their pre to post samples for both Cr(VI) and Cr(III). A significant difference was also found between pre and post EBC samples for Cr(III) in welders. This study has shown that EBC has the potential to be a valid, non-invasive biological matrix to assess occupational exposure to Cr(VI) and Cr(III) for biological monitoring assessment, with the ability to detect low level inhalation exposures.

Association of environmental exposure to chromium with differential DNA methylation: An epigenome-wide study

Introduction: Previous studies have reported that chromium (Cr)-induced epigenetic alterations and DNA methylation play a vital role in the pathogenesis of diseases induced by chromium exposure. Epigenomic analyses have been limited and mainly focused on occupational chromium exposure; their findings are not generalizable to populations with environmental Cr exposure. Methods: We identified the differential methylation of genes and regions to elucidate the mechanisms of toxicity related to environmental chromium exposure. DNA methylation was measured in blood samples collected from individuals in Cr-contaminated (n = 10) and unexposed areas (n = 10) by using the Illumina Infinium HumanMethylation850K array. To evaluate the relationship between chromium levels in urine and CpG methylation at 850 thousand sites, we investigated differentially methylated positions (DMPs) and differentially methylated regions (DMRs) by using linear models and DMRcate method, respectively. The model was adjusted for biologically relevant variables and estimated cell-type compositions. Results: At the epigenome-wide level, we identified five CpGs [cg20690919 (p _{FDR =}0.006), cg00704664 (p _{FDR =}0.024), cg10809143 (p _{FDR =}0.043), cg27057652 (p _{FDR =}0.047), cg05390480 (p _{FDR =}0.024)] and one DMR (chr17: 19,648,718-19,648,972), annotated to ALDH3A1 genes (p < 0.05) as being significantly associated with log₂ transformed urinary chromium levels. Discussion: Environmental chromium exposure is associated with DNA methylation, and the significant DMPs and DMR being annotated to cause DNA damage and genomic instability were found in this work. Research involving larger samples is required to further explore the epigenetic effect of environmental chromium exposure on health outcomes through DNA methylation.

Spatial and temporal distribution and influencing factor analysis of the malignant tumor mortality rate around the mining area

Mining activities can threaten residents' health even lives. Integrating spatial empirical Bayesian smoothing, joinpoint regression and spatiotemporal scanning methods, we analyzed aggregations and possible factors of four tumor mortality rates at township and village scales from 2012 to 2016 in Suxian district of Hunan Province, China. Results indicate: (1) Mortality rates were ranked: lung cancer > liver cancer > gastric cancer > colorectal cancer. (2) Lung cancer had a higher five-year mortality rate in the middle; relative risk (RR) of death from lung cancer from 2012 to 2015 in Xujiadong Village was 7.48. Liver cancer had a higher five-year mortality rate in the Middle West; RR in areas centered on Nanta Street with a radius of 9.87 km from 2015 to 2016, was 1.83. Gastric cancer had a higher five-year mortality rate in the east; RR in Xujiadong Village from 2012 to 2014 was 6.9. Five-year mortality rate of colorectal cancer was higher in the northwest; RR in regions centered on Huangcao Village with a radius of 12.11 km in 2016, was 2.88. (3) Pollution from ore mining and smelting, heavy metal and non-metallic, and mine transportation were the main possible factors. This research provides a method reference for studying spatiotemporal patterns of disease in China even the world.

Information needs, approaches, and case studies in human health risk communication

This article uses ten case studies to illustrate the information needs, various communication approaches, and the communicator's role in explaining environmental health risks from a variety of hazards, to a variety of audiences, over time frames from days to years, using in person consultation, lectures, zooms, and email formats. Events often had a long history before the communication began and may have had a long tail afterward. Audiences may be public officials, companies, workers, communities, or individuals. Each individual may have their own understanding or mental model regarding the hazard, exposure, and risk. The communicator's role or intention may be to reassure an audience that has unrealistic exaggerated concerns or fears or to protect a client if the fears are realistic. Or it may be altruistic to inform a complacent audience to take the risks it faces more seriously. Although risk assessment research has advanced the techniques for communicating abstruse probabilities to audiences with low numeracy, in my experience, audiences are unimpressed by precise-sounding probability numbers, and are more interested in whether exposure is occurring or may occur and how to stop it. Often audiences have reason to be outraged and may be more concerned about punishing wrong doers than about the hazard itself, particularly when the exposure is past and cannot be undone. Thus, there is a difference between discussing the riskiness of a situation (risk communication) and what you are going to do about the situation (risk management). Risk communication is successful when the audience responds as intended, calming down or taking action. These case studies are drawn from a large number of risk communication experiences that I and my Rutgers colleagues have engaged in over the past four decades. Through the 20th century, New Jersey was the most densely industrialized State in United States. New Jersey experienced growth of the chemical and petrochemical industries and the unfortunately profligate disposal of toxic wastes. Having the most Superfund sites of any state is a dubious distinction, but New Jersey also has the most experience in evaluating and responding to these hazards.

Topical issues of prevention of stomach cancer: A review

Prevention of gastric cancer, both primary and secondary, is an extremely important component of the management of gastroenterological patients. The correct collection of anamnesis with an assessment of the hereditary (family) cancer risk, the action of risk factors (eating disorders, habitual/chronic intoxication, obesity, Helicobacter pylori infection, etc.), as well as the use of gastroprotectors (in particular, the drug Regastim Gastro), especially in persons with potentially precancerous the condition is chronic atrophic gastritis. According to the data of a double-blind placebo-controlled randomized study Regastim Gastro (active ingredient alpha-glutamyl tryptophan) in the treatment of chronic atrophic gastritis, it was found that this drug has a powerful anti-inflammatory effect and regenerative activity. Taking the drug Regastim Gastro, compared with placebo, statistically significantly contributed to a decrease in the number of inflammatory infiltration cells per 1 mm2 of the gastric mucosa. Regastim Gastro decreases in eosinophilic (3 times) and neutrophilic (4 times) infiltration of the gastric mucosa and also reduced the number of macrophages, lymphocytes and plasmocytes. In addition to anti-inflammatory properties, the drug also had a pronounced regenerative effect. Taking of Regastim Gastro statistically significant (p=0.028) increases in the number of glands per 1 mm2 of the gastric mucosa by 26.1% compared with the initial screening indicators. In the group of patients taking placebo, on the contrary, there was a further progression of the pathological process, accompanied by a decrease in the number of glands per 1 mm2 of the gastric mucosa after the end of treatment in comparison with the initial indicators. After the course of therapy, the number of glands per 1 mm2 of the gastric mucosa in patients taking the drug Regastim Gastro was statistically significantly higher in comparison with the results in the placebo group (p=0.013). After the course of Regastim Gastro, there was an improvement in acid production: a shift in the acidic side of the average pH value (1.6 times) and an increase in the value of the acidity index, both when compared with the initial values (5.4 times) and in comparison with the placebo group (2.9 times). The intake of Regastim Gastro to patients with gastritis, both H. pylori (+) and H. pylori (-) before the development of atrophy of the gastric mucosa can reduce the inflammatory factor, prevent the occurrence of atrophy and may have maximum anti-carcinogenic action.

Natural source of Cr(VI) in soil: The anoxic oxidation of Cr(III) by Mn oxides

Cr(VI) from oxidation of geogenic Cr(III) minerals is gradually becoming the primary source of Cr(VI) in soils and groundwater instead of direct emissions. Thermodynamically, natural oxidants of Cr(III) are limited to O₂ and Mn oxides. The oxidation of Cr(III) occurs commonly in oxic soils but the difference in the oxidative dissolution of Cr(III) by Mn oxides in different redox soils (especially under anoxic conditions) is not fully understood and field evidence is lacking. Here, the relationship between Cr(VI) and Mn oxides in basalt-origin soil profiles under three different redox conditions (anoxic, suboxic and oxic) was studied. The oxidative dissolution of chromite was validated by synthesising δ-MnO₂ that was close to biogenic Mn oxides under anoxic and oxic conditions. In anoxic soils, high levels of Cr(VI) were detected in the same horizons as those where Cr(III)-minerals co-existed with Mn(III/IV) oxides, suggesting an exclusive pathway for Cr(VI) generation through oxidation by Mn oxides where there was a deficiency of other oxidants, such as O₂. In oxic soils, the highly abundant Fe oxides combined with Cr(III) to form Cr(III)-Fe(III) oxyhydroxides and Cr(VI) was generated mainly via slow oxidation by O₂. The chromite oxidation experiment results also indicated that a high abundance of Mn oxides could promote chromite oxidative dissolution to generate Cr(VI), even under anoxic conditions. Additionally, the form of Cr and the reactivity and abundance of Mn oxides and reducing agents controlled the net content of Cr(VI) in the soil. This study showed that, even under reducing conditions, Cr(III) is readily oxidised by Mn oxides to generate Cr(VI) in reductant-deficient and Mn-rich soils, which may lead to the continuous introduction of Cr(VI) into groundwater and agricultural soils.

A Review on Recent Progress in Organic Fluorimetric and Colorimetric Chemosensors for the Detection of Cr3+/6+Ions

Chromium occurs in the environment primarily in two valence states, trivalent Cr3+ and hexavalent Cr6+, which have different physicochemical and biochemical properties. However, the higher concentration of Cr3+/6+ can cause various adverse effects on human health. Therefore, detecting Cr3+/6+ ions is important in various samples. Colorimetric and fluorescent chemosensors are the most powerful tools for the detection of Cr3+/6+ ions. These chemosensors have excellent bioimaging capability and significant sensitivity and selectivity. In this article, different colorimetric and fluorescent chemosensors based on organic compounds, including Schiff base, antipyrine, diarylethene, pyrene, crown ether, dansyl, pyridine, thiazole, coumarin, boradiazaindacene, rhodamine, imidazole, hydrazone, and other functional groups for detection of Cr3+/6+ ions have been reviewed, classified them according to different fluorophore and recognition mode. I hope this article will help the readers for the future design of highly effective, sensitive, and selective chemosensors for the detection and determination of Cr3+/6+ ions.

Road sediment, an underutilized material in environmental science research: A review of perspectives on United States studies with international context

Road sediment is a pervasive environmental medium that acts as both source and sink for a variety of natural and anthropogenic particles and often is enriched in heavy metals. Road sediment is generally understudied in the United States (U.S.) relative to other environmental media and compared to countries such as China and the United Kingdom (U.K.). However, the U.S. is an ideal target for these studies due to the diverse climates and wealth of geochemical, socioeconomic, demographic, and health data. This review outlines the existing U.S. road sediment literature while also providing key international perspectives and context. Furthermore, the most comprehensive table of U.S. road sediment studies to date is presented, which includes elemental concentrations, sample size, size fraction, collection and analytical methods, as well as digestion procedure. Overall, there were observed differences in studies by sampling time period for elemental concentrations, but not necessarily by climate in the U.S. Other key concepts addressed in this road sediment review include the processes controlling its distribution, the variety of nomenclature used, anthropogenic enrichment of heavy metals, electron microscopy, health risk assessments, remediation, and future directions of road sediment investigations. Going forward, it is recommended that studies with a higher geographic diversity are performed that consider smaller cities and rural areas. Furthermore, environmental justice must be a focus as community science studies of road sediment can elucidate pollution issues impacting areas of high need. Finally, this review calls for consistency in sampling, data reporting, and nomenclature to effectively expand work on understudied elements, particles, and background sediments.

Hexavalent Chromium Causes Apoptosis and Autophagy by Inducing Mitochondrial Dysfunction and Oxidative Stress in Broiler Cardiomyocytes

Hexavalent chromium (Cr(VI)) is a common environmental pollutant, which has a strong toxic effect on humans and animals. However, the cardiac toxicity of Cr(VI) in broilers remains to be explored. The development of heart disease is often linked to mitochondrial dysfunction especially exposure to toxic substances. In order to investigate the role of mitochondrial dysfunction in apoptosis and autophagy of broiler cardiomyocytes induced by hexavalent chromium, broiler cardiomyocytes were cultured in potassium dichromate of 0 mM, 16 mM, and 32 mM medium for 24 h. The results showed that, compared with the control group, reactive oxygen species (ROS) and apoptosis rate in the Cr(VI) treatment group increased in a dose-dependent manner, the mRNA levels of apoptosis-related genes Bax and p53 were significantly increased, and the mRNA level of Bcl-2 was significantly decreased. Compared with the control group, the mRNA level of autophagy-related genes (LC3-I, LC3-II, and Beclin1) in the Cr(VI) treatment group was significantly increased, the mRNA level of mTOR was significantly decreased, and the protein level of p62/SQSTM1 was significantly decreased. The protein level of Beclin1 and the ratio of LC3-II/LC3-I significantly increased. In addition, compared with the control group, mitochondrial membrane potential decreased in a dose-dependent manner, and mitochondrial dynamics-related genes SIRT1, SIRT3, and Mfn2 mRNA decreased significantly in the Cr(VI) treatment group. In this study, we concluded that Cr(VI) could cause broiler myocardial apoptosis and autophagy by inducing mitochondrial dysfunction and oxidative stress.

Hexavalent chromium induces centrosome amplification through ROS-ATF6-PLK4 pathway in colon cancer cells

Centrosome amplification (CA) refers to a numerical increase in centrosomes resulting in cells with more than two centrosomes. CA has been shown to initiate tumorigenesis and increase the invasive potential of cancer cells in genetically modified experimental models. Hexavalent chromium is a recognized carcinogen that causes CA and tumorigenesis as well as promotes cancer metastasis. Thus, CA appears to be a biological link between chromium and cancer. In the present study we investigated how chromium triggers CA. Our results showed that a sub-toxic concentration of chromium induced CA in HCT116 colon cancer cells, resulted in the production of reactive oxygen species (ROS), activated ATF6 without causing endoplasmic reticulum stress, and upregulated the protein level of PLK4. Inhibition of ROS production, ATF6 activation, or PLK4 upregulation attenuated CA. Inhibition of ROS using N-acetyl-L-cysteine (NAC) inhibited chromium-induced activation of ATF6 and upregulation of PLK4. ATF6-specific siRNA knocked down the protein level and activation of ATF6, and upregulated PLK4, with no effect on ROS production. Knockdown of PLK4 protein had no effect on chromium-induced ROS production or activation of ATF6. In conclusion, our results suggest that hexavalent chromium induces CA via the ROS-ATF6-PLK4 pathway and provides molecular targets for inhibiting chromium-mediated CA, which may be useful for the assessment of CA in chromium-promoted tumorigenesis and cancer cell metastasis. This article is protected by copyright. All rights reserved.

Ultrasound Image-Guided Nerve Block Combined with General Anesthesia under an Artificial Intelligence Algorithm on Patients Undergoing Radical Gastrectomy for Gastric Cancer during and after Operation

This study was aimed at investigating the location of gastric cancer by using a gastroscope image based on an artificial intelligence algorithm for gastric cancer and the effect of ultrasonic-guided nerve block combined with general anesthesia on patients undergoing gastric cancer surgery. A total of 160 patients who were undergoing gastric cancer surgery from March 2019 to March 2021 were collected as the research objects, and the convolutional neural network (CNN) algorithm was used to segment the gastroscope image of gastric cancer. The patients were randomly divided into a simple general anesthesia group of 80 cases and a transversus abdominis plane block combined with rectus abdominis sheath block combined with the general anesthesia group of 80 cases. Then, compare the systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) at the four time points T0, T1, T2, and T3. The times of analgesic drug use within 48 hours after operation and postoperative adverse reactions were recorded. The visual analog scale (VAS) scores were also recorded at 4 h, 12 h, 24 h, and 48 h. The results show that the image quality after segmentation is good: the accuracy of tumor location is 75.67%, which is similar to that of professional endoscopists. Compared with the general anesthesia group, the transversus abdominis plane block combined with the rectus sheath block combined with the general anesthesia group had fewer anesthetics, and the difference was statistically significant (P < 0.05). Compared with the general anesthesia group, SBP, DBP, and HR were significantly reduced at T1, T2, and T3 in the transverse abdominis plane block combined with rectus sheath block and general anesthesia group (P < 0.05). Compared with the simple general anesthesia group, the VAS scores of the transversus abdominis plane block combined with rectus sheath block combined with the general anesthesia group decreased at 4 h, 12 h, and 24 h after surgery, and the difference was statistically significant (P < 0.05). The number of analgesics used in transversus abdominis plane block combined with the rectus sheath block combined with the general anesthesia group within 48 hours after operation was significantly less than that in the general anesthesia group, and the difference was statistically significant (P < 0.05). The average incidence of adverse reactions in the nerve block combined with the general anesthesia group was 2.5%, which was lower than the average incidence of 3.75% in the general anesthesia group. In summary, the CNN algorithm can accurately segment the lesions in the ultrasonic images of gastric cancer, which was convenient for doctors to make a more accurate judgment on the lesions, and provided a basis for the preoperative examination of radical gastrectomy for gastric cancer. Ultrasonic-guided nerve block combined with general anesthesia can effectively improve the analgesic effect of radical gastrectomy for gastric cancer, reduced intraoperative and postoperative adverse reactions and analgesic drug dosage, and had a good effect on postoperative recovery of patients. The combined application of these two methods can further improve the precision treatment of gastric cancer patients and accelerate postoperative recovery.

Assessment of intestinal injury of hexavalent chromium using a modified in vitro gastrointestinal digestion model

Intestinal injury assessment of hexavalent chromium (Cr-VI) in humans is crucial for quantifying assessment of adverse health risk posed by the intake of Cr (VI)-contaminated water. To overcome the deficiency in simulating human gastric reduction and intestinal absorption, we modified the constituents of simulated gastric fluid in in vitro digestion method by adding reductants glutathione (18 μM) and ascorbic acid (180 μM), which incorporated with human intestinal epithelial model to construct an in vitro gastrointestinal digestion (IVGD) model for intestinal injury assessment. Cr-VI bioaccessibility results from IVGD model showed that weak gastric acidity significantly increased the intestinal accessible Cr-VI dose by 22.41-38.43 folds. The time-course intestinal absorption indicated prolongation of intestinal exposure destroyed the intestinal epithelium, and 24 h after Cr-VI treatment was a good time point to perform intestinal absorption and toxicity assessment. A series of cell-based bioassays provided initial warning of adverse effect, suggesting that epithelial integrity exhibited greatest sensitivity to Cr-VI exposure and might be used as a sensitive marker for the toxicity assessment of oral exposure to Cr-VI. Notably, this study provides a feasible strategy for delineation of Cr-VI biotransformation and intestinal injury following ingestion exposure, which contributes to address the toxicity data gap of low-dose exposure in humans and puts forward a reference for intestinal toxicity assessment of other chemicals.

Enhanced removal of Cr(VI) by nitrogen-doped hydrochar prepared from bamboo and ammonium chloride

N-doped biochar can effectively eliminate toxic Cr(VI). Here, N-doped hydrochar (NHC) was successfully synthesized by one-pot hydrothermal carbonization (HTC) of NH₄Cl and bamboo, and employed to adsorb Cr(VI). The specific surface area, pore volume, and carbon and nitrogen contents of NHC all increase compared with the undoped hydrochar (HC). NH₄Cl acts as a cheap nitrogen source to enhance the nitrogen content of hydrochar and as an acid catalyst to accelerate hydrochar carbonization. Adsorption experiments show NHC has higher adsorption capacity than HC for Cr(VI). XPS and FTIR imply the dominant mechanisms of adsorbing Cr(VI) onto two hydrochars are electrostatic attraction, reduction and complexation, but the contributions of surface functional groups in two hydrochars for elimination of Cr(VI) differ. The doped nitrogen in NHC is pivotal in adsorbing and reducing Cr(VI). Hence, NHC prepared from bamboo and NH₄Cl by one-step HTC is a cheap and efficient adsorbent to eliminate aqueous Cr(VI).

Genome wide profiling of miRNAs relevant to the DNA damage response induced by hexavalent chromium exposure (DDR-related miRNAs in response to Cr (VI) exposure)

AIM

We aimed to explore the expression of miRNAs and their potential roles in the DNA damage response (DDR) induced by Cr (VI) exposure in human B lymphoblast cells (HMy2.CIR cells) and in a population of Cr (VI)-exposed humans.

METHODS

Differentially expressed miRNAs were found by a combination of miRNA sequencing and RT-qPCR validation in HMy2.CIR cells treated with K₂Cr₂O₇. Differentially expressed miRNAs related to DDR were selected for functional study. The expression levels of differential miRNAs were also investigated in chromate workers.

RESULTS

A total of 214 differentially expressed miRNAs were identified by sequencing, and the expression of 5 miRNAs among 25 associated with DDR was found to be consistent between sequencing and validation studies.Functional studies showed that miR-148a-3p, miR-21-5p, and miR-424-3p might be related to Cr (VI)-induced cell apoptosis, and miR-221-3p might participate in Cr (VI)-induced DDR. We also found that the expression of miR-21-5p and miR-424-3p was upregulated in chromate workers.

CONCLUSIONS

Cr (VI) exposure could significantly impact miRNAs expression in vitro and in chromate workers. Functional studies showed that miR-148a-3p, miR-21-5p and miR-221-3p might take a crucial role in the cellular DDR induced by Cr (VI) exposure.

Evaluating tissue levels of the eight trace elements and heavy metals among esophagus and gastric cancer patients: A comparison between cancerous and non-cancerous tissues

BACKGROUND

Considering the affecting role of environmental factors including trace elements and heavy metals on the upper gastrointestinal (GI) cancers, there is paucity of empirical research in tissue evaluations.

OBJECTIVES

The present study aimed to measure the tissue content of some trace elements and heavy metals such as zinc (Zn), chromium (Cr), manganese (Mn), tin (Sn), copper (Cu), aluminum (Al), lead (Pb), and iron (Fe) in esophagus and gastric cancerous tissues compared to the adjacent healthy tissues.

METHODS

In a cross-sectional study, the aforementioned trace elements and heavy metals were evaluated among patients with esophagus and gastric cancers. During endoscopy, multiple samples were taken from cancerous lesions and the adjacent healthy tissues. The classic flame atomic absorption spectroscopy (FAAS) method was employed as the study framework.

RESULTS

Fifty patients with the mean age of 53.92 ± 8.73 were enrolled in the current study. Thirteen patients suffered from esophageal cancer and thirty-seven patients were afflicted with gastric cancer. The results revealed significant differences in the median concentrations of Zn, Cr, Sn and, Cu (P < 0.05) between the two groups. Although there were no significant changes in the tissue content in the esophageal samples, in the median concentrations of Zn, Cr and, Sn (P < 0.05) in gastric tissues, significant differences were observed. Further, the results indicated that gender enacted an affecting role in the level of some trace elements and heavy metals.

CONCLUSION

The tissue contents of some elements were altered in gastric and esophageal cancers; this difference may reflect the underlying mechanism of cellular changing during the tumorigenesis or direct exposure of these elements. It seems that under the shade of other coexisting risk factors, larger cohort studies are suggested to be conducted to investigate other probable aspects in this area of interest.

Association between trace element concentrations in cancerous and non-cancerous tissues with the risk of gastrointestinal cancers in Eastern Iran

This study was conducted to investigate the association between trace elements including cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), nickel (Ni), selenium (Se), zinc (Zn), and arsenic (As) in gastrointestinal cancer tissue and non-cancerous tissue (suspected gastrointestinal cancer) in Eastern Iran. The samples of 63 gastrointestinal cancers (stomach (n = 20), esophageal (n = 19), and colorectal (n = 24) along with 63 controls in South Khorasan Province, Iran, were collected and analyzed using ICP-MS (Agilent 7900). Our results indicated that the concentrations of Co (1.3 ± 0.8, 1.3 ± 0.8 μg kg^-1), Cr (8.1 ± 7.3, 11.0 ± 14.8 μg kg^-1), Ni (29.0 ± 20.1, 39.5 ± 30.2 μg kg^-1), Pb (6.9 ± 4.0, 6.1 ± 4.6 μg kg^-1), and Zn (867.6 ± 159.1, 935.6 ± 196.2 μg kg^-1) were significantly higher among esophagus and colon cancer cases than controls (p < 0.05). Similarly, stomach cancer cases showed higher Co, Cr, Ni, Se, and Zn and lower Cu concentrations than their controls (p < 0.05). Moreover, the Spearman correlation between metals revealed a mostly low to moderate correlation between metals. Our finding illustrated that the significant risk differences of Cr, Ni, Pb, Se, and Zn metals on esophagus cancer when considered the single predictor unadjusted for other metals and covariates RD (95% CI) - Cr: -0.274 (-0.463, -0.086), Ni: -0.288 (-0.457, -0.118), Pb: -0.171 (-0.463, -0.086), Se: -0.243 (-0.434, -0.051), and Zn: -0.094 (-0.143, -0.045) respectively. This study suggests that the trace element's exposure may be associated with gastrointestinal cancer risk. Additional studies are needed to elucidate the mechanisms underlying trace element carcinogenesis further.

Occupational exposure to hexavalent chromium. Part II. Hazard assessment of carcinogenic effects

Hexavalent chromium (Cr(VI)) compounds have been studied extensively and several agencies have described their toxicological profile. In the past, personnel of the Dutch Ministry of Defence may have been exposed to Cr(VI) during maintenance activities on NATO equipment. To investigate if this exposure may have caused irreversible adverse health effects, the Dutch National Institute for Public Health and the Environment (RIVM) summarized all available knowledge from previous evaluations. This information was complemented with a scoping review to retrieve new scientific literature. All scientific evidence was evaluated in workshops with external experts to come to an overview of irreversible adverse health effects that could be caused by occupational exposure to Cr(VI) compounds. This review provides the hazard assessment for occupational exposure to Cr(VI) and carcinogenic effects by integrating and weighting evidence provided by international agencies complemented with newly published studies. It was concluded that occupational exposure to Cr(VI) can cause lung cancer, nose and nasal sinus cancer in humans. Cr(VI) is suspected to cause stomach cancer and laryngeal cancer in humans. It is currently insufficiently clear if Cr(VI) can cause cancer of the small intestine, oral cavity, pancreas, prostate or bladder in humans.

Direct embryotoxicity of chromium (III) exposure during preimplantation development

Chromium in its trivalent form (chromium (III)) is an essential component of a balanced diet, and its deficiency disturbs glucose and lipid metabolism in humans and animals. The prevailing view is that chromium (III) is notably less toxic than chromium (VI), which is genotoxic and carcinogenic. Thus, the biotransformation of environmental chromium (VI) to chromium (III) is a promising and environmentally friendly detoxification method. However, increasing evidence suggests that chromium (III) induces considerable cytotoxicity. However, the toxicity of chromium (III) to early embryos remains largely unknown. In the present study, we used in vitro fertilization (IVF) to produce mouse embryos and identified the direct embryotoxicity of chromium (III). On exposure to high concentrations of CrCl₃, blastocyst formation almost completely failed and a large proportion of embryos were arrested at the 2- to 4-cell stage. At low concentrations of CrCl₃, IVF embryos showed a significant decrease in blastocyst formation, reduced total cell numbers, aberrant lineage differentiation, increased oxidative stress, and apoptosis. We also found that chromium (III) exposure during the preimplantation stage, even at low concentrations, led to impaired post-implantation development. Thus, our study substantiates the direct embryotoxicity of chromium (III) during preimplantation development and prolonged impairment of development potential. The results further highlight the potential adverse effects of chromium (III) on public reproductive health with respect to increased environmental enrichment of and dietary supplementation with chromium (III) complexes.

Analysis of serum metabolome of workers occupationally exposed to hexavalent chromium: A preliminary study

Hexavalent chromium (Cr(VI)) compound is considered as a common environmental and occupational pollutant due to widespread application in industry and agriculture. Cr(VI) as a carcinogen poses a serious threat to human health and the underlying mechanisms need further investigation. Previous studies had demonstrated the characteristic expression profiling after Cr(VI) treatment in vitro and in vivo at the levels of gene and protein. The comprehensive metabolic signatures were also conducive to discover potential biomarkers for effects assessment of Cr(VI) toxicity. In the current study, Ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS) non-targeted metabolomics was applied to analyze serum metabolic changes in 77 chromate exposure workers and 62 controls. Thirteen metabolites were found significantly decreased and 41 metabolites were increased, which were involved in arginine and proline metabolism, and glycerophospholipid metabolism by bioinformatic analysis. Furthermore, there were significant negative correlations between blood Cr level and Arginine, PC(18:2/24:4) and PC(14:0/16:0), subgroup analyses indicated that these correlations were observed in male-only subgroups, and were not found among chromate workers and controls separately. Diet could be a potential confounder which was not controlled rigorously in this study. These findings provided preliminary clues to investigate the underlying mechanisms of Cr(VI)-induced toxicity and were required to be further verified in future researches.

Biomarkers of effect as determined in human biomonitoring studies on hexavalent chromium and cadmium in the period 2008-2020

A number of human biomonitoring (HBM) studies have presented data on exposure to hexavalent chromium [Cr(VI)] and cadmium (Cd), but comparatively few include results on effect biomarkers. The latter are needed to identify associations between exposure and adverse outcomes (AOs) in order to assess public health implications. To support improved derivation of EU regulation and policy making, it is of great importance to identify the most reliable effect biomarkers for these heavy metals that can be used in HBM studies. In the framework of the Human Biomonitoring for Europe (HBM4EU) initiative, our study aim was to identify effect biomarkers linking Cr(VI) and Cd exposure to selected AOs including cancer, immunotoxicity, oxidative stress, and omics/epigenetics. A comprehensive PubMed search identified recent HBM studies, in which effect biomarkers were examined. Validity and applicability of the markers in HBM studies are discussed. The most frequently analysed effect biomarkers regarding Cr(VI) exposure and its association with cancer were those indicating oxidative stress (e.g., 8-hydroxy-2'-deoxyguanosine (8-OHdG), malondialdehyde (MDA), glutathione (GSH)) and DNA or chromosomal damage (comet and micronucleus assays). With respect to Cd and to some extent Cr, β-2-microglobulin (B2-MG) and N-acetyl-β-D-glucosaminidase (NAG) are well-established, sensitive, and the most common effect biomarkers to relate Cd or Cr exposure to renal tubular dysfunction. Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule (KIM)-1 could serve as sensitive biomarkers of acute kidney injury in response to both metals, but need further investigation in HBM studies. Omics-based biomarkers, i.e., changes in the (epi-)genome, transcriptome, proteome, and metabolome associated with Cr and/or Cd exposure, are promising effect biomarkers, but more HBM data are needed to confirm their significance. The combination of established effect markers and omics biomarkers may represent the strongest approach, especially if based on knowledge of mechanistic principles. To this aim, also mechanistic data were collected to provide guidance on the use of more sensitive and specific effect biomarkers. This also led to the identification of knowledge gaps relevant to the direction of future research.

Formaldehyde and Brain Disorders: A Meta-Analysis and Bioinformatics Approach

While there is significant investigation and investment in brain and neurodegenerative disease research, current understanding of the etiologies of illnesses like Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and brain cancer remains limited. Environmental exposure to the pollutant formaldehyde, an emerging neurotoxin widely used in industry, is suspected to play a critical role in mediating these disorders, although findings are limited and inconsistent. Focusing on highly exposed groups, we performed a meta-analysis of human epidemiological studies of formaldehyde and neurodegenerative disease (N =  19) or brain tumors (N = 12). To assess the biological plausibility of observed associations, we then conducted a bioinformatics analysis using WikiPathways and the Comparative Toxicogenomics Database and identified candidate genes and pathways that may be related to these interactions. We reported the meta-relative risk (meta-RR) of ALS following high exposures to formaldehyde was increased by 78% (meta-RR = 1.78, 95% confidence interval, CI 1.20-2.65). Similarly, the meta-RR for brain cancer was increased by 71% (meta-RR = 1.71; 95% CI 1.07-2.73) among highly exposed individuals. Multiple sensitivity analyses did not reveal sources of heterogeneity or bias. Our bioinformatics analysis revealed that the oxidative stress genes superoxide dismutase (SOD1, SOD2) and the pro-inflammatory marker tumor necrosis factor (TNF) were identified as the top relevant genes, and the folate metabolism, vitamin B12 metabolism, and the ALS pathways were highly affected by formaldehyde and related to the most brain diseases of interest. Further inquiry revealed the two metabolic pathways are also intimately tied with the formaldehyde cycle. Overall, our bioinformatics analysis supports the link of formaldehyde exposure to ALS or brain tumor reported from our meta-analysis. This new multifactorial approach enabled us to both interrogate the robustness of the epidemiological data and identify genes and pathways that may be involved in these interactions, ultimately lending strong evidence and potential biological plausibility for the association between formaldehyde exposure and brain disease.

Smartphone-enabled field monitoring tool for rapid hexavalent chromium detection in water

Chromium contamination of soil and water is a serious environmental and public health concern as the hexavalent form of chromium [Cr(VI)] is readily soluble in water and is a confirmed carcinogen. There is an imminent need for a robust, low-cost, and simple analytical technique to facilitate in situ monitoring of Cr(VI) in water. Current quantitative methods of Cr(VI) detection are largely laboratory-based, time-consuming, expensive, and require training for implementation. In this contribution, a portable, easy-to-use, and compact measuring tool is presented that provides Cr(VI) concentration within 10 min of water sampling over a linear range of 0-3 mg L^-1. This tool utilizes a relatively inexpensive camera-enabled smartphone with a custom-made test chamber attachment to seamlessly perform Cr(VI) measurements on water samples in the field. For analysis, an android-based software application was developed that directs the user to perform a simple series of steps following the diphenylcarbazide-based colorimetric method prescribed by the American Public Health Association. The tool was validated against a standard UV-visible spectrophotometer for a variety of synthetic and naturally contaminated water samples, with correlation factors greater than 0.993 (p < .001). The colorimetric method was also validated against a non-colorimetric Cr(VI) detection technique-ion chromatography-inductively coupled plasma mass spectrometry. Furthermore, Cr(VI) detection limits for the smartphone-enabled colorimetric method were found to be within 1.3-11.6 μg L^-1, which were significantly better than reported for commercially available field test kits, and even surpassed the limits exhibited by a typical spectrophotometer (25-50 μg L^-1). Finally, real-time mapping of source waters at a contaminated site was demonstrated by remote logging of Cr(VI) water quality data and corresponding GPS coordinates into a cloud server. This study highlights the potential role of smartphone-based monitoring tool in providing information to the affected community and enabling safe access to drinking water. An accurate, robust, simple-to-use, and economic method to measure hexavalent chromium in water within 10 min of sampling at site.

Hexavalent chromium induced heart dysfunction via Sesn2-mediated impairment of mitochondrial function and energy supply

Hexavalent chromium (Cr(VI)), the most toxic valence state of chromium, is widely present in industrial effluents and wastes. Although previous study has reported that Cr(VI) can cause cytomembrane structure impairment by aggravating lipid peroxidation in the heart, the detailed mechanism of Cr(VI)-induced heart dysfunction is still unclear. Sesn2, a novel antioxidant and stress-inducible molecule, is evidenced to protect against various cardiometabolic diseases such as atherosclerosis and cardiomyopathy. To define the potential mechanism of heart dysfunction induced by chronic Cr(VI) exposure, Wistar rats were intraperitoneal injected with potassium dichromate (K₂Cr₂O₇) for 35 d in the present study. The data showed that chronic K₂Cr₂O₇ exposure caused dose-dependently hematological variations, oxidative stress, dysfunction, and disorganized structure of heart, cardiomyocyte apoptosis, ATP depletion, and mitochondria impairment in rats. In addition, the expressions of Drp1 and Bax were increased by K₂Cr₂O₇. However, the suppression of Mfn2, PGC-1α, Sesn2, nuclear Nrf2, HO-1, and NQO1 protein levels was observed in K₂Cr₂O₇-treated rat hearts. In conclusion, these results demonstrate that chronic K₂Cr₂O₇ exposure dose-dependently causes heart dysfunction, and the molecular mechanism of this event is associated with the loss of Sesn2 mediated mitochondrial function and energy supply impairment.

Challenges and recommendations on the conduct of systematic reviews of observational epidemiologic studies in environmental and occupational health

Systematic reviews are powerful tools for drawing causal inference for evidence-based decision-making. Published systematic reviews and meta-analyses of environmental and occupational epidemiology studies have increased dramatically in recent years; however, the quality and utility of published reviews are variable. Most methodologies were adapted from clinical epidemiology and have not been adequately modified to evaluate and integrate evidence from observational epidemiology studies assessing environmental and occupational hazards, especially in evaluating the quality of exposure assessments. Although many reviews conduct a systematic and transparent assessment for the potential for bias, they are often deficient in subsequently integrating across a body of evidence. A cohesive review considers the impact of the direction and magnitude of potential biases on the results, systematically evaluates important scientific issues such as study sensitivity and effect modifiers, identifies how different studies complement each other, and assesses other potential sources of heterogeneity. Given these challenges of conducting informative systematic reviews of observational studies, we provide a series of specific recommendations based on practical examples for cohesive evidence integration to reach an overall conclusion on a body of evidence to better support policy making in public health.

Mitophagy Induced by Mitochondrial Function Damage in Chicken Kidney Exposed to Cr(VI)

Cr(VI) is a heavy metal environmental pollutant and carcinogen. Excessive Cr(VI) exposure injures kidneys. This study aimed to investigate mitophagy induced by mitochondrial function damage in chicken kidney exposed to Cr(VI). To explore the mechanism involved, we randomly divided 40 one-day-old Hy-line Brown cockerels into four groups, with each group exposed to different concentrations of Cr(VI), i.e., 0, 10, 30 and 50 mg kg^-1, which were orally administered daily for 45 days. Excessive Cr(VI) increased tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and chemokine (C-X-C motif) ligand 1(CXCL1) expression and decreased Ca²⁺-adenosine triphosphatase (Ca²⁺-ATPase), Mg²⁺-ATPase and Na⁺/k⁺-ATPase activities in chicken kidney. Furthermore, Cr(VI) significantly increased reactive oxygen species (ROS) production and induced mitochondrial membrane potential (MMP) collapse and typical autophagosome formation. With the increase of Cr(VI) concentration, the Parkin translocation, value of LC3-II increased and decreased the content of p62/SQSTM1 and the translocase of outer mitochondrial membrane 20 (TOMM20). In summary, our findings explicated that mitochondrial function damage and mitophagy-related indicators were related to Cr(VI) concentration in chicken kidney.

Attenuation of potassium dichromate and sodium arsenite toxicities by methanol extract of Rauvolfia vomitoria in mice

OBJECTIVES

Exposure to arsenic and hexavalent chromium is a major public health concern especially in the developing part of the world and there is paucity of information on reliable treatment modalilities. It is in this regard that this study evaluates the efficacy of methanol leaf extract of Rauvolfia vomitoria (MRV) when used as pretreatment agent against potassium dichromate (K₂Cr₂O₇) and sodium arsenite (NaAsO₂) exposure.

METHODS

Swiss albino mice between 7 and 10 weeks old were divided into eight cohorts of five animals each. Treatment groups consisted of a distilled water control, MRV alone (275 mg/kg po daily), K₂Cr₂O₇ (12.0 mg/kg, single ip injection) +/- MRV pretreatment, NaAsO₂ (2.5 mg/kg, single ip injection) +/- MRV pretreatment, Na₂AsO₂ + K₂Cr₂O₇ +/- MRV pretreatment. MRV was given for seven consecutive days, while K₂Cr₂O₇ and NaAsO₂ were injected on day seven of the experiment. The frequency of micronucleated polychromatic erythrocytes (mPCEs) was determined in bone marrow cells, while aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were assessed in the plasma. Hepatic glutathione (GSH), malondialdehyde (MDA), catalase (CAT) and glutathione-S-transferase (GST) levels were also determined.

RESULTS

The NaAsO₂ and K₂Cr₂O₇ significantly (p<0.05) increased mPCE formation, AST, ALT, and CAT when compared with the control. Simultaneous exposure to NaAsO₂ and K₂Cr₂O₇ further increased the levels of the markers. Furthermore, GSH and GST were significantly reduced by NaAsO₂ or K₂Cr₂O₇ or their combination. Pretreatment with MRV reversed the markers towards that of control.

CONCLUSIONS

Methanol extract of Rauvolfia vomitoria may therefore ameliorate NaAsO₂ and K₂Cr₂O₇-induced toxicities via reduction of oxidative stress and fortification of anti-oxidant system.

A review on fly ash from coal-fired power plants: chemical composition, regulations, and health evidence

Throughout the world, coal is responsible for generating approximately 38% of power. Coal ash, a waste product, generated from the combustion of coal, consists of fly ash, bottom ash, boiler slag, and flue gas desulfurization material. Fly ash, which is the main component of coal ash, is composed of spherical particulate matter with diameters that range from 0.1 μm to >100 μm. Fly ash is predominately composed of silica, aluminum, iron, calcium, and oxygen, but the particles may also contain heavy metals such as arsenic and lead at trace levels. Most nations throughout the world do not consider fly ash a hazardous waste and therefore regulations on its disposal and storage are lacking. Fly ash that is not beneficially reused in products such as concrete is stored in landfills and surface impoundments. Fugitive dust emissions and leaching of metals into groundwater from landfills and surface impoundments may put people at risk for exposure. There are limited epidemiological studies regarding the health effects of fly ash exposure. In this article, the authors provide an overview of fly ash, its chemical composition, the regulations from nations generating the greatest amount of fly ash, and epidemiological evidence regarding the health impacts associated with exposure to fly ash.

Cancer risks of firefighters: a systematic review and meta-analysis of secular trends and region-specific differences

PURPOSE

The objective of this study was to conduct a systematic review and meta-analysis to evaluate the cancer risks among firefighters in the time course and from different geographical areas.

METHOD

A PubMed search was performed to identify cohort studies about cancer risk and firefighting presented with standardized incidence ratios (SIRs) or standardized mortality ratios (SMRs). Using random-effect models, meta-relative risk estimates (mSIRs, mSMRs) and 95% confidence intervals (CI) were assessed. Cohort studies with employment starting before 1950 were classified as "old", studies starting between 1950 and 1970 as "medium", and later studies as "new".

RESULTS

The general cancer risk of firefighters was similar to the general population, but mSMR decreased over time (new studies: mSMR = 0.81, 95% CI 0.70-0.92). We observed an increase of mSIR for melanoma of the skin and prostate cancer as well as a decrease of mSIR for stomach cancer with later employment onset. For those cancer sites, we did not observe a secular trend of mSMRs. Regional differences between relative cancer risks were particularly observed for bladder cancer.

CONCLUSIONS

Among other things, innovative firefighting techniques and better personal protective equipment have provided a safer and healthier working environment for firefighters over time leading to a reduction of overall cancer incidence and mortality ratios. Increased general preventive medical checkups and possible additional screenings for firefighters might have led to more findings of malignant melanoma of the skin and prostate cancer in the recent past.

Polyaniline@magnetic chitosan nanomaterials for highly efficient simultaneous adsorption and in-situ chemical reduction of hexavalent chromium: Removal efficacy and mechanisms

Devising new versatile nano-adsorbents for efficient capturing of heavy metals in water represents one important direction for environmental remediation. Here, the application of a novel polyaniline@magnetic chitosan (PANI@MCTS) composite consisting of numerous nitrogen-containing functional groups and magnetic Fe₃O₄ nanoparticles was reported for the efficient treatment of chromium-containing wastewater. This material exhibited a fast adsorption kinetics (80% removal efficiency within 15 min) and strong adsorption capacity (186.6 mg(Cr(VI))•g^-1(PANI@MCTS)) for removing Cr(VI) in water as well as an excellent magnetic separation ability. The adsorption of Cr(VI) was found to follow the Langmuir isotherm model and comply with the pseudo-second-order kinetics. More importantly, the PANI@MCTS could facilitate the in-situ chemical reduction of Cr(VI) to Cr(III) that enabled the detoxification treatment of Cr(VI) in water. XPS analysis revealed the simultaneous adsorption and in-situ chemical reduction of Cr(VI) on the PANI@MCTS, where the coordination and electrostatic interaction between Cr(VI) and the positively charged nitrogen containing functional groups contributed to the adsorption, and the = N-/-NH- groups served as active redox pair triggered the in-situ chemical reduction reaction. The recycle experiment showed an excellent stability of this material with >90% removal efficiency after five repeats of treatment. This work provides a promising alternative material for the effective treatment of chromium-containing wastewater.

Study of Trace Metal Imbalances in the Scalp Hair of Stomach Cancer Patients with Different Types and Stages

Stomach cancer is among the most common forms of cancers, and diet and environmental factors play important roles in its malignancy. This study was conducted to evaluate the trace metal contents in the scalp hair of stomach cancer patients and healthy donors to investigate probable relationship between metal imbalances and cancer. The samples were digested in HNO₃-HClO₄ mixture and the metals were quantified by flame atomic absorption spectrophotometry. Median level of Cr was found to be significantly higher in the patients than in the controls, while median levels of Fe, Mn and Cd were considerably reduced. The correlation pattern of metals in the patients manifested significantly divergent mutual relationships compared with the controls. Multivariate analyses showed appreciably diverse apportionment of the metals in the patients and healthy donors. Variations in the metal levels were also observed for various types (adenocarcinoma and gastrointestinal stromal tumour) as well as stages (I, II, III and IV) of stomach cancer patients. Most of the metals revealed noticeable disparities in their levels based on gender, habitat, dietary habit and smoking habit of patients and controls. Accordingly, the essential/toxic metals exhibited significant imbalance due to pathogenesis of stomach among the patients.

DNA-protein crosslinks from environmental exposure: Mechanisms of formation and repair

Many environmental carcinogens cause DNA damage, which can result in mutations and other alterations in genomic DNA if not repaired promptly. Because of the bulkiness of the lesions, DNA-protein crosslinks (DPCs) are one of the types of toxic DNA damage with potentially deleterious consequences. Despite the importance of DPCs, how cells remove these complex DNA adducts has been incompletely understood. However, major progress in the DPC repair field over the past 5 years now supports the view that cells are equipped with multiple mechanisms to cope with DPCs. Here, we first provide an overview of environmental substances that induce DPCs, describing the sources of exposure and mechanisms of DPC formation. We then review current models of DPC repair and discuss their significance for environmental carcinogens.

Ribosomal DNA copy number is associated with P53 status and levels of heavy metals in gastrectomy specimens from gastric cancer patients

The ribosomal DNA (rDNA) can act as a sensor and responder of cancer-associated stress. Here we investigated rDNA copy number in gastric cancers and its association with existing biomarkers and metals exposure. This study was performed on paired tumor and adjacent normal tissues obtained from 65 gastric cancer patients who underwent gastrectomy. Immunohistochemistry was used to assess HER-2, E-cadherin, EGFR, CK (pan), CK20, CK7, TopoⅡ, CAM5.2, P53, and Ki-67 expression. Inductively coupled plasma mass spectrometry (ICP-MS) was used to detect the concentrations of 17 metals in gastric tissues. rDNA copy number was detected by qPCR in genomic DNA isolated from tissue samples. Associations between the expression of existing markers, metal concentrations, and rDNA copy number were evaluated. Within patients with gastric cancer, the copy number of the 45S rDNA components (18S, 5.8S, 28S) and the 5S rDNA in tumor tissues were significantly higher than those in adjacent normal tissues, whereas mitochondrial DNA (mtDNA) copy number was significantly lower in tumor tissues than that in adjacent normal tissues. Further analysis revealed that the increase in 18S, 5.8S, and 28S rDNA copy number in tumor tissues was diminished in the context of EGFR and P53 loss. Moreover, analysis of metals revealed particularly high concentrations of As, Cd, Cr, Cu and Fe in the gastric tissues of these patients. Intriguingly, rDNA copy number variation across individuals was correlated with the concentrations of some metals. The rDNA was amplified in tumor tissues of gastric cancer patients, and its amplification may be associated with metals exposure. The expression of EGFR and P53 may influence rDNA copy number, with diminished amplification of the rDNA in cancers that were negative for these biomarkers. Our observation further our understanding of rDNA copy number in gastric cancer and its potential as a simple and useful marker in gastric cancer monitoring.

Heavy metals interfere with plasma metabolites, including lipids and amino acids, in patients with breast cancer

The aim of the present study was to examine the association between plasma heavy metals and the metabolome in patients with breast cancer (BC), and the association with cancer development. Nuclear magnetic resonance was used to determine the metabolites involved and an inductively coupled plasma mass spectrometry system was used to quantify the heavy metals in the plasma samples. It was indicated that cadmium was significantly higher in the plasma of patients with BC compared with that in the control population (~15-fold increase). Chromium, arsenic and lead were also elevated in the plasma of patients with BC by ~3.24, 2.14 and 1.52 fold, respectively. A number of small molecules, including amino acids and salts, were altered in the plasma of patients with BC compared with the control population. Another notable finding in this investigation was that plasma lipid levels were elevated in patients with BC compared with those in the control population. The findings of the present study suggest that exposure to heavy metals, including cadmium, arsenic, chromium and lead, may influence blood lipid levels and other small molecule metabolites, which in turn may be involved in BC development. Further studies surrounding urinary heavy metals and the metabolome are required to further determine the impact of metals on metabolism and on BC development.

Long-term hexavalent chromium exposure facilitates colorectal cancer in mice associated with changes in gut microbiota composition

Colorectal cancer (CRC) is among the leading causes of cancer-related mortality worldwide. Hexavalent chromium [Cr(VI)] is often present in groundwater. Chronic Cr(VI) exposure is suggested to be one of the main factors inducing cancer. However, the correlation between Cr(VI) and CRC remains unclear. In this study, we investigated the role of Cr(VI) in CRC by establishing a mouse CRC model induced by 1, 2-dimethylhydrazine (DMH). The results showed that Cr(VI) increased weight loss in DMH-induced mice and promoted the formation of tumors. Cr(VI) also increased DMH-induced proliferating cell nuclear antigen (PCNA) levels. Investigation of the underlying mechanisms found that Cr(VI) significantly decreased DMH-induced SOD, GSH and CAT levels, while, the MDA level increased. Metagenomic analyses found that the abundance of Firmicutes and Bacteroidetes in the DMH + Cr group was down-regulated. Interestingly, the combination of Cr(VI) and DMH significantly increased the abundance of Verrucomicrobia. At the family and genus levels, families Akkermansiaceae and Saccharimonadaceae and genus Akkermansia were more abundant in the DMH + Cr group, whereas the abundance of short-chain fatty acid (SCFA)-producing bacteria (family Muribaculaceae, family Lachnosipiraceae, genus Lachnospiraceae_NK4A136_group, and genus Roseburia) decreased. These results indicate that Cr(VI) might aggravate CRC by altering the composition of the gut microflora.

Evaluation of heavy metals and metabolites in the urine of patients with breast cancer

Epidemiologic studies demonstrated that the environment serves a crucial role in cancer development. Heavy metals, including arsenic (As), cadmium (cd), chromium (Cr), lead and mercury, are considered to be carcinogens or co-carcinogens. Furthermore, Cd has been detected in breast cancer (BC) tissue at high concentrations. The present study aimed to investigate the correlation between heavy metals detected in urine and urine metabolome of patients with BC, and their association with cancer development. Nuclear magnetic resonance was used to determine urine metabolites and an inductively coupled plasma mass spectrometry system was used to detect heavy metals in urine samples. The results demonstrated that Cd was markedly increased in the urine of patients with BC compared with the control population (approximately 2-fold). Cr and As were also increased in the urine of patients with BC. In addition, numerous small molecule metabolites were altered in the urine of patients with BC compared with the control population. This study also demonstrated that alterations in small molecule metabolites in the urine of patients with BC were very similar to results from a previous report. These findings indicated that environmental exposure to Cd, As, or Cr could influence the urine levels of metabolites, which may be involved in BC development. Further investigation is therefore required to examine a larger range of samples from different countries or areas in order to understand the impact of heavy metals on metabolism and BC development.

Sulforaphane attenuates hexavalent chromium-induced cardiotoxicity via the activation of the Sesn2/AMPK/Nrf2 signaling pathway

Hexavalent chromium (Cr(vi)), the most toxic valence state of chromium, is widely present in industrial effluents and wastes. Sulforaphane (SFN), rich in Brassica genus plants, bears multiple biological activity. Wistar rats were used to explore the protective role of SFN against the cardiotoxicity of chronic potassium dichromate (K2Cr2O7) exposure and reveal the potential molecular mechanism. The data showed that SFN alleviated hematological variations, oxidative stress, heart dysfunction and structure disorder, and cardiomyocyte apoptosis induced by K2Cr2O7. Moreover, SFN reduced p53, cleaved caspase-3, Bcl2-associated X protein, nuclear factor kappa-B, and interleukin-1β levels, and increased Sesn2, nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1, NAD(P)H quinone oxidoreductase-1, and phosphorylated adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) levels. This study demonstrates that SFN ameliorates Cr(vi)-induced cardiotoxicity via activation of the Sesn2/AMPK/Nrf2 signaling pathway. SFN may be a protector against Cr(vi)-induced heart injury and a novel therapy for chronic Cr(vi) exposure.