Mechanisms of chromium toxicity, carcinogenicity and allergenicity: review of the literature from 1985 to 2000

Associations between atmospheric PM2.5 exposure and carcinogenic health risks: Surveillance data from the year of lowest recorded levels in Beijing, China

Scant research has pinpointed the year of minimum PM2.5 concentration through extensive, uninterrupted monitoring, nor has it thoroughly assessed carcinogenic risks associated with analyzing numerous components during this nadir in Beijing. This study endeavored to delineate the atmospheric PM2.5 pollution in Beijing from 2015 to 2022 and to undertake comprehensive evaluation of carcinogenic risks associated with the composition of atmospheric PM2.5 during the year exhibiting the lowest concentration. PM2.5 concentrations were monitored gradually in 9 districts of Beijing for 7 consecutive days per month from 2015 to 2022, and 32 kinds of PM2.5 components collected in the lowest PM2.5 concentration year were analyzed. This comprehensive dataset served as the basis for carcinogenic risk assessment using Monte Carlo simulation. And we applied the Positive Matrix Factorization (PMF) method to identity the sources of atmospheric PM2.5. Furthermore, we integrated this source appointment model with risk assessment model to discern the origins of these risks. The findings revealed that the annual average PM2.5 concentration in 2022 stood at 43.1 μg/m3, marking the lowest level recorded. The mean carcinogenic risks of atmospheric PM2.5 exposure calculated at 6.30E-6 (empirical 95% CI 1.09E-6 to 2.25E-5) in 2022. The PMF model suggested that secondary sources (35.4%), coal combustion (25.6%), resuspended dust (15.1%), biomass combustion (14.1%), vehicle emissions (7.1%), industrial emissions (2.0%) and others (0.7%) were the main sources of atmospheric PM2.5 in Beijing. The mixed model revealed that coal combustion (2.41E-6), vehicle emissions (1.90E-6) and industrial emissions (1.32E-6) were the main sources of carcinogenic risks with caution. Despite a continual decrease in atmospheric PM2.5 concentration in recent years, the lowest concentration levels still pose non-negligible carcinogenic risks. Notably, the carcinogenic risks associated with metals and metalloids exceeded that of PAHs. And the distribution of risk sources did not align proportionally with the distribution of PM2.5 mass concentration.

A novel zwitterionic magnetic nanocomposite developed for non-invasive speciation analysis of inorganic chromium

3-(2-Aminoethylamino)propyltriethoxysilane and carboxyethylsilanetriol sodium salt were grafted on silica-coated Fe3O4 nanoparticles via sol-gel process to prepare novel amine- and carboxyl-bifunctionalized magnetic nanocomposites (SMNPs-(NH2 + COOH)). After well characterized, this doubly functionalized material was used as magnetic solid-phase extraction (MSPE) adsorbent to separate and enrich inorganic chromium species followed by inductively coupled plasma-mass spectrometry detection. The optimization of MSPE operation parameters including pH was conducted. It is reasonably elucidated that the adsorption mechanisms of zwitterionic SMNPs-(NH2 + COOH) towards chromium species are electrostatic and/or coordination interactions. Cr(VI) and Cr(III) can be adsorbed around pH 3.0 and around 10.0 respectively with strong anti-interference ability not only from other co-existing ions but also from the two labile species each other, and eluted by dilute nitric acid solution. With a 15-fold enrichment factor, the limits of detection of Cr(VI) and Cr(III) were 0.008 and 0.009 μg L-1, respectively, profiting from the maximum adsorption capacities of 7.52 and 6.11 mg g-1. The just one magnetic extraction matrix based speciation scheme possesses excellent convenience and friendliness to Cr(VI) and Cr(III) without any oxidation or reduction prior to capture of these two species. This protocol has been successfully applied to the speciation analysis of inorganic chromium in real-world environmental water samples.

Evaluating the Impact of Airborne Fine Particulate Matter and Heavy Metals on Oxidative Stress via Vitamin Supplementation

This cross-sectional study aimed to assess the interrelationships between PM2.5 exposure, heavy metal concentrations, and oxidative stress indicators, while evaluating the impact of antioxidant intake, such as vitamins, on these associations. PM2.5 exposure assessments were conducted using portable sensor-based monitors; biomarker analyses for heavy metals and oxidative stress were performed in 114 non-smoking adults. We observed that personal or ambient PM2.5 exposure levels were not associated with increased levels of heavy metals in blood and urine, nor with oxidative stress levels in urine. However, the concentrations of cadmium and lead in blood, and those of chromium and nickel in urine, were significantly associated with the urinary malondialdehyde (MDA) concentration. Additionally, increases in blood cadmium, urinary chromium, and nickel levels were significantly associated with higher urinary MDA concentrations in the non-vitamin-supplement group, but this trend was not observed in the regular vitamin supplement group. Our findings suggest that a regular intake of vitamin supplements might modulate the relationship between heavy metal exposure and oxidative stress, indicating potential protective effects against oxidative damage induced by PM2.5 and heavy metals. This study highlights the complexity of environmental pollutant exposure and its impact on human health, emphasizing the need for further research to elucidate the underlying mechanisms and explore potential protective strategies.

Aerogels of Polypyrrole/Tannic Acid with Nanofibrillated Cellulose for the Removal of Hexavalent Chromium Ions

The preparation of conducting polymer aerogels is an effective strategy to produce innovative materials with enhanced physicochemical properties. Herein, polypyrrole (PPy) aerogels were oxidatively prepared in the presence of tannic acid (TA) with different concentrations (2.5, 5, and 10% mole ratio to pyrrole monomer) under freezing conditions. Nanofibrillated cellulose (NFC) was added during the PPy/TA synthesis to enhance mechanical stability. The effect of TA concentration on the aerogels' morphology, conductivity, thermal stability, and adsorption capacity was investigated. The conductivity of 9.6 ± 1.7 S cm-1 was achieved for PPy/TA prepared with 2.5% TA, which decreased to 0.07 ± 0.01 S cm-1 when 10% TA was used. PPy/TA aerogels have shown high efficacy in removing Cr(VI) ions from aqueous solutions. Adsorption experiments revealed that all the aerogels follow pseudo-second-order kinetics. PPy/TA prepared with NFC has a maximum adsorption capacity of 549.5 mg g-1.

Sustainable carbon sequestration via olivine based ocean alkalinity enhancement in the east and South China Sea: Adhering to environmental norms for nickel and chromium

Enhancing silicate weathering to increase oceanic alkalinity, thereby facilitating the absorption of atmospheric carbon dioxide (CO2), is considered a highly promising technique for carbon sequestration. This study aims to evaluate the feasibility and potential of olivine-based ocean alkalinity enhancement (OAE) for the removal of atmospheric CO2 and its storage in seawater as bicarbonates in the East and South China Seas (ESCS). A particular focus is placed on the potential ecological impacts arising from the release of nickel (Ni) and chromium (Cr) during the olivine weathering process. We considered two extreme scenarios: one where Ni and Cr are entirely retained in seawater, and another where they are completely deposited in sediments. These scenarios respectively represent the maximum permissible concentrations of Ni and Cr in seawater and sediments during the OAE process. Current marine environmental quality standards (EQS) were utilized as the threshold limits for Ni and Cr in both seawater and sediment, with concentrations exceeding these EQS potentially leading to significant adverse effects on marine life. When all released Ni is retained in seawater, the allowable dosage of olivine varies from 0.05 to 13.7 kg/m2 (depending on olivine particle size, temperature, and water depth); when all released Ni is captured by sediment, the permissible addition of olivine ranges from 0.21 to 2.1 kg/m2 (depending on mixing depth). Given the low solubility of Cr, it is not necessary to consider the scenario where Cr exceeds the limit in seawater. The allowable amount of Cr entirely retained in sediments ranges from 0.69 to 47.2 kg/m2.In most scenarios, the accumulation of metals in sediments preferentially exceeds the corresponding threshold value rather than remaining in seawater. Therefore, we recommend using alkalization equipment to fully dissolve olivine before discharging into the sea, enabling a larger-scale application of olivine without significant negative ecological impacts.

Evaluation of Aflatoxins and Heavy Metals Exposure in the Local Feeds of Fish and Shrimp in Bangladesh

This study aims to comprehensively assess the presence of aflatoxins, pervasive fungal toxins, and heavy metals (lead, chromium, cadmium) in the local feed of fish and shrimp. Forty-eight samples of the fish and shrimp feed were collected from the Dhaka and Sathkhira districts of Bangladesh respectively. Aflatoxins (B1, B2, G1, G2) were analyzed by high-performance liquid chromatography (HPLC) with fluorescence detector, and atomic absorption spectrophotometry (AAS) was used for the heavy metal detection after sample digestion. The standard analytical methods of the Association of Official Analytical Chemists were followed for analyzing the proximate composition of the feed samples. The findings revealed the high toxic concentration of total aflatoxins particularly in fish feed (196.25 μg/kg). Concurrently, varying concentrations of heavy metals, including lead (Pb) and chromium (Cr), were detected, with the highest levels found in shrimp feed at 3.324 and 174.6 mg/kg, respectively. In comparison, highest contamination of cadmium (Cd) was found in fish feed at 0.398 mg/kg. The outcomes are growing concerns regarding the quality of locally sourced feed and emphasizing the need for prompt corrective actions. Otherwise, neglecting this concern may lead to the possibility of both fish and, ultimately, humans who consume them being vulnerable to the absorption and accumulation of these assessed toxic compounds.

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.

Semi-quantitative health risk assessment of heavy metal dust exposure among nail technicians using the SQRA technique and Monte Carlo simulation

Nail technology, including the application of artificial nails and nail care, is a developing sector of the global beauty industry. Nail technicians are exposed to a variety of chemical substances through inhalation, as they spend extended periods of time in close proximity to these materials. This study aimed to evaluate the semi-quantitative health risk of dust-containing heavy metals among nail technicians. This analytical descriptive study employed the risk assessment method provided by the Singapore Occupational Health Department to evaluate the health hazards of lead, cadmium, nickel, chromium, and manganese. Dust samples from nail filing were collected from the respiratory zone of 20 nail technicians following the NIOSH 7300 method. The samples were analyzed using ICP-OES instrumentation. Monte Carlo simulation was utilized to characterize the risk and its uncertainties. Manganese and cadmium had the highest and lowest mean concentrations, respectively. The risk scores of the metals ranked from highest to lowest were as follows: N i > C r > C d > M n > P b . All five metals had risk rankings below 2.8, signifying a minimal risk level. Sensitivity analysis using Spearman's correlation coefficient demonstrated a positive relationship between concentration, daily hours of exposure, and the number of workdays per week with the risk score (RR) and exposure level (ER). Conversely, the variable of weekly working hours (W) showed a negative correlation with these parameters. Despite the low-risk level of the examined metals, continuous exposure and potential long-term effects on nail technicians warrant preventive measures. Recommendations include implementing local exhaust ventilation systems, using table fans, establishing work-rest cycles, wearing N95 dust masks, and using reputable and high-quality nail polishes.

Heavy Metal Exposure and Cardiovascular Disease

Heavy metals are harmful environmental pollutants that have attracted widespread attention due to their health hazards to human cardiovascular disease. Heavy metals, including lead, cadmium, mercury, arsenic, and chromium, are found in various sources such as air, water, soil, food, and industrial products. Recent research strongly suggests a connection between cardiovascular disease and exposure to toxic heavy metals. Epidemiological, basic, and clinical studies have revealed that heavy metals can promote the production of reactive oxygen species, which can then exacerbate reactive oxygen species generation and induce inflammation, resulting in endothelial dysfunction, lipid metabolism distribution, disruption of ion homeostasis, and epigenetic changes. Over time, heavy metal exposure eventually results in an increased risk of hypertension, arrhythmia, and atherosclerosis. Strengthening public health prevention and the application of chelation or antioxidants, such as vitamins and beta-carotene, along with minerals, such as selenium and zinc, can diminish the burden of cardiovascular disease attributable to metal exposure.

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.

Concentration, spatial distribution, and non-carcinogenic risk assessment of arsenic, cadmium, chromium, and lead in drinking water in rural areas of eight cities of West Azarbaijan province, Iran

Exposure to heavy metals through drinking water can cause significant adverse health effects. The aim of the present study was to investigate the concentration, spatial distribution, and assessment of non-carcinogenic risk attributed to exposure to arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb) in rural areas of eight cities of the West Azerbaijan province of Iran. Eighty-five water samples were taken from randomly selected drinking water wells in the rural areas, and the concentration of the heavy metals was measured by using standard methods. The concentration distribution maps were drawn, and the non-carcinogenic health risks for ingestion and dermal exposure pathways were calculated in four age groups (including infants, children, teenagers, and adults). According to the obtained results, arsenic is considered as the most worrying pollutant among the investigated heavy metals. The maximum measured concentration for arsenic was 371.9 μg/L, which is 37 times the maximum permissible limit. The results of the health risk assessment illustrate that exposure to heavy metals via dermal contact do not pose significant non-carcinogenic risks. However, the calculated non-carcinogenic risks for oral exposure to arsenic were very high and concerning. The highest hazard quotient for oral exposure to arsenic was related to rural of city G (82.64). It is recommended to take the necessary measures as soon as possible regarding the supply of safe drinking water in the studied areas.

Control priority based on source-specific DALYs of PM2.5-bound heavy metals by PMF-PSCF-IsoSource model in urban and suburban Beijing

To determine the priority control sources, an approach was proposed to evaluate the source-specific contribution to health risks from inhaling PM2.5-bound heavy metals (PBHMs). A total of 482 daily PM2.5 samples were collected from urban and suburban areas of Beijing, China, between 2018 and 2019. In addition to the PMF-PSCF model, a Pb isotopic IsoSource model was built for more reliable source apportionment. By using the comprehensive indicator of disability-adjusted life years (DALYs), carcinogenic and noncarcinogenic health risks could be compared on a unified scale. The study found that the annual average concentrations of the total PBHMs were significantly higher in suburban areas than in urban areas, with significantly higher concentrations during the heating season than during the nonheating season. Comprehensive dust accounted for the largest contribution to the concentration of PBHMs, while coal combustion contributed the most to the DALYs associated with PBHMs. These results suggest that prioritizing the control of coal combustion could effectively reduce the disease burden associated with PBHMs, leading to notable public health benefits.

Determination of hexavalent chromium in textiles of daily use by ion chromatography and dermal risk assessment

The determination of hexavalent chromium in textiles and clothes is challenging since during extraction, the original oxidation state should not be altered. Since, as a matter of fact, current analytical methods are focused only on total chromium determination, the purpose of this research is to develop a reliable analytical method for the determination of Cr(VI) in textiles and tissues of daily use for a reliable application of risk analysis models, which are usually based on total Cr data. After optimization, a 0.0025 M Na3PO4 extraction solution was selected for the extraction of Cr(VI) from textiles. This solution minimizes possible interconversion redox reactions and interference, and provides good extraction recoveries (88.4 ± 2.5% - 105.5 ± 0.6 %, according to Cr(VI) concentration) and quantitation limits (0.017 mg/kg), fully complying the current limits set for Cr(VI) in textiles in contact with skin, and for leachable Cr(VI). The developed method was validated investigating intra-day repeatability (n = 10) and inter-day repeatability (n = 30) which were below 12%, and matrix effect which was below 6% confirming the precision of the method and the negligibility of a matrix interference during the whole analysis. The method, which was proved to be suited also for bioaccessibility studies in saliva and sweat, was applied to the analysis of tank top, coloured paper napkin, polyamide tights, panties, highlighting Cr(VI) content in the panties only at very low concentration (0.028 mg/kg). As verified by ECHA and US EPA approaches, this amount does not pose a non-carcinogenic risk for human health. As regards carcinogenic risk, considering both adult and child exposure, the dermal contact with the panties poses an acceptable risk (R ≤ 10-6).

Inhalation exposure to toxic heavy metals in nail salon technicians and health risk assessment using Monte Carlo simulation

OBJECTIVE

Nail salons offer a developing and diverse occupation for many women, especially the new generation. Due to the increasing apprehension surrounding heavy metals in dust caused by filing nails containing dried nail polish, the present study was designed aimed to health risk assessment of heavy metals in breathing zone of nail salon technicians (NSTs).

METHODS

This is a cross-sectional study that was conducted in NSTs. The concentration of Cadmium (Cd), Lead (Pb), Nickel (Ni), Chromium (Cr) and Manganese (Mn)in breathing zone of 20 NSTs was determined using ICP-OES.

RESULTS

The metal concentrations were in the following order: Mn > Pb > Ni > Cr > Cd with corresponding arithmetic mean values of0.008, 0.0023, 0.0021, 0.001 and 0.0006 mg m-3, respectively, which are exceeded the recommended levels stated in the indoor air guidelines. The average lifetime carcinogenic risk (LCR) for Cr, Cd, Ni and Pb was calculated 0.0084, 0.00054, 0.00026 and 1.44 E - 05, respectively. The LCR values of all metals (except Pb) exceeded the acceptable level set by the USEPA. The mean of Hazard quotients (HQ) for Mn, Cd, Cr, Ni and Pb were calculated to be23.7, 4.74, 2.19, 0.51 and 0.0.24, respectively. The sensitivity analysis showed that, the exposure frequency (EF) for Cr and Ni had the strong effects on generation of both LCR and HQ. Furthermore, the concentrations of Mn, Cd and Pb had strong impacts on the HQ generation and the concentration of Cd and Pb had main effects on LCR generation.

CONCLUSION

To effectively reduce pollutant concentration, it is recommended to install a ventilation system near nail salon work tables and conduct continuous monitoring and quality control of nail products.

Reactivity of metal-oxo clusters towards biomolecules: from discrete polyoxometalates to metal-organic frameworks

Metal-oxo clusters hold great potential in several fields such as catalysis, materials science, energy storage, medicine, and biotechnology. These nanoclusters of transition metals with oxygen-based ligands have also shown promising reactivity towards several classes of biomolecules, including proteins, nucleic acids, nucleotides, sugars, and lipids. This reactivity can be leveraged to address some of the most pressing challenges we face today, from fighting various diseases, such as cancer and viral infections, to the development of sustainable and environmentally friendly energy sources. For instance, metal-oxo clusters and related materials have been shown to be effective catalysts for biomass conversion into renewable fuels and platform chemicals. Furthermore, their reactivity towards biomolecules has also attracted interest in the development of inorganic drugs and bioanalytical tools. Additionally, the structural versatility of metal-oxo clusters allows for the efficiency and selectivity of the biomolecular reactions they promote to be readily tuned, thereby providing a pathway towards reaction optimization. The properties of the catalyst can also be improved through incorporation into solid supports or by linking metal-oxo clusters together to form Metal-Organic Frameworks (MOFs), which have been demonstrated to be powerful heterogeneous catalysts. Therefore, this review aims to provide a comprehensive and critical analysis of the state of the art on biomolecular transformations promoted by metal-oxo clusters and their applications, with a particular focus on structure-activity relationships.

Synergistic/antagonistic toxicity characterization and source-apportionment of heavy metals and organophosphorus pesticides by the biospectroscopy-bioreporter-coupling approach

Many anthropogenic chemicals are manufactured and eventually enter the surrounding environment, threatening food security and human health. Considering the additive or synergistic effects of pollutant mixtures, there is an expanding need for rapid, cost-effective and field-portable screening methods in environmental monitoring. This study used a recently developed biospectroscopy-bioreporter-coupling (BBC) approach to investigate the binary toxicity of Ag(I), Cr(VI) and four organophosphorus pesticides (dichlorvos, parathion, omethoate and monocrotophos). Ag(I) and Cr(VI) altered the toxicity mechanisms of pesticides, explained by the synergistic or antagonistic effect of Ag/Cr-induced cytotoxicity and pesticide-induced genotoxicity. The discriminating Raman spectral peaks associated with organophosphorus pesticides were 1585 and 1682 cm-1, but 750, 1004, 1306 and 1131 cm-1 were found in heavy metal and pesticide mixtures. More spectral alterations were related to pesticides rather than Ag(I) or Cr(VI), hinting at the dominant toxicity mechanisms of pesticides in mixtures. Ag(I) supplement significantly increased the levels of reactive oxygen species induced by organophosphorus pesticides, attributing to the increased permeability of cell membrane and entrance of toxic substances into the cells by the oligodynamic actions. This study lends deeper insights into the interactions between microbes and pollutant mixtures, offering clues to assess the cocktail effects of multiple pollutants comprehensively.

Advances in Group VI Metal-Catalyzed Homogeneous Hydrogenation and Dehydrogenation Reactions

Transition metal-catalyzed homogeneous hydrogenation and dehydrogenation reactions for attaining plethora of organic scaffolds have evolved as a key domain of research in academia and industry. These protocols are atom-economic, greener, in line with the goal of sustainability, eventually pave the way for numerous novel environmentally benign methodologies. Appealing progress has been achieved in the realm of homogeneous catalysis utilizing noble metals. Owing to their high cost, less abundance along with toxicity issues led the scientific community to search for sustainable alternatives. In this context, earth- abundant base metals have gained substantial attention culminating enormous progress in recent years, predominantly with pincer-type complexes of nickel, cobalt, iron, and manganese. In this regard, group VI chromium, molybdenum and tungsten complexes have been overlooked and remain underdeveloped despite their earth-abundance and bio-compatibility. This review delineates a comprehensive overview in the arena of homogeneously catalysed (de)hydrogenation reactions using group VI base metals chromium, molybdenum, and tungsten till date. Various reactions have been described; hydrogenation, transfer hydrogenation, dehydrogenation, acceptorless dehydrogenative coupling, hydrogen auto transfer, along with their scope and brief mechanistic insights.

Effects of chromate on nitrogen removal and microbial community in two-stage vertical-flow constructed wetlands

Nitrogen and chromium (Cr(VI)) pollution in waterbodies pose great threats to human health, and a cost-effective alternative with Cr(VI) and nitrogen simultaneous removal is still needed. This study investigated the influence of Cr(VI) on nitrogen removal in the two-stage vertical-flow constructed wetlands (TS-VFCWs) along with iron ore and woodchip, and explored relationship between Cr(VI) and nitrogen removal. The results showed that efficient Cr(VI) and nitrogen removal were simultaneously achieved in TS-VFCWs together with iron-ore and woodchip under 2 mg/L-Cr(VI), whereas 10 mg/L-Cr(VI) gave significant and recoverable inhibition of nitrogen removal. Cr(VI) supplementation promoted the beneficiation of Cr(VI)-reducing/resistant bacteria IMCC26207 and Bryobacter on iron-ore. Woodchip enriched Cr(VI)-reducing bacteria Streptomyces and Thiobacillus. XRD and XPS showed that abundant bound-Cr existed in the surface of iron ore and woodchip, and Cr(III) precipitation/oxide was the major product. High abundances of nitrifying and autotrophic/heterotrophic denitrifying bacteria ensured good nitrogen removal at Cr(VI) stress.

Exploring the potential function of trace elements in human health: a therapeutic perspective

A trace element, known as a minor element, is a chemical element whose concentration is very low. They are divided into essential and non-essential classes. Numerous physiological and metabolic processes in both plants and animals require essential trace elements. These essential trace elements are so directly related to the metabolic and physiologic processes of the organism that either their excess or deficiency can result in severe bodily malfunction or, in the worst situations, death. Elements can be found in nature in various forms and are essential for the body to carry out its varied functions. Trace elements are crucial for biological, chemical, and molecular cell activity. Nutritional deficits can lead to weakened immunity, increased susceptibility to oral and systemic infections, delayed physical and mental development, and lower productivity. Trace element enzymes are involved in many biological and chemical processes. These compounds act as co-factors for a number of enzymes and serve as centers for stabilizing the structures of proteins and enzymes, allowing them to mediate crucial biological processes. Some trace elements control vital biological processes by attaching to molecules on the cell membrane's receptor site or altering the structure of the membrane to prevent specific molecules from entering the cell. Some trace elements are engaged in redox reactions. Trace elements have two purposes. They are required for the regular stability of cellular structures, but when lacking, they might activate alternate routes and induce disorders. Therefore, thoroughly understanding these trace elements is essential for maintaining optimal health and preventing disease.

Porous MgNiO2 Chrysanthemum Flower Nanostructure Electrode for Toxic Hg2+ Ion Monitoring in Aquatic Media

A simple hydrothermal synthesis approach was used to synthesize porous MgNiO2 Chrysanthemum Flowers (CFs) nanostructures and applied as a sensing electrode for quick detection of hazardous mercury (Hg2+ ions). The morphological, structural, and electrochemical properties of MgNiO2 CFs were investigated. The morphological characteristic of MgNiO2 CFs, with a specific surface area of 45.618 m2/g, demonstrated strong electrochemical characteristics, including cations in different oxidation states of Ni3+/Ni2+. Using a three-electrode system for electrochemical detection, the MgNiO2 CFs based electrode revealed a good correlation coefficient (R2) of ~0.9721, a limit of detection (LOD) of ~11.7 μM, a quick response time (10 s), and a sensitivity of 8.22 μA∙μM-1∙cm-2 for Hg2+ ions over a broad linear range of 10-100 μM. Moreover, the selectivity for Hg2+ ions in tap water and drinking water was determined, and a promising stability of 25 days by MgNiO2 CFs electrode was exhibited. The obtained results indicate that the developed MgNiO2 CFs are a promising electrode for detecting hazardous Hg2+ ions in water and have the potential to be commercialized in the future.

Hourglass shaped polyoxometalate-based materials as electrochemical sensors for the detection of trace Cr(VI) in a wide pH range

Due to Chromium hexavalent Cr(VI) is one of the most carcinogenic toxic ions, it is essential for finding a low-cost, efficient and highly selective detection method. Considering the wide range of pH detection in water, a major issue is exploring high sensitive electrocatalyst. Thus, two crystalline materials with hourglass {P₄Mo₆} clusters in different metal centers were synthesized and had fabulous Cr(VI) detection performance in a wide pH range. At pH = 0, the sensitivities of CUST-572 and CUST-573 were 133.89 μA μM^-1 and 30.05 μA μM^-1, and the detection limits (LODs) of Cr(VI) were 26.81 nM and 50.63 nM which met World Health Organization (WHO) standard for drinking water. CUST-572 and CUST-573 also had good detection performance at pH = 1-4. In actual water samples, CUST-572 and CUST-573 also possessed sensitivities of 94.79 μA μM^-1 and 20.09 μA μM^-1 and LODs were 28.25 nM and 52.24 nM, showing high selectivity and chemical stability. The difference of the detection performance of CUST-572 and CUST-573 were mainly attributed to the interaction between {P₄Mo₆} and different metal centers of crystalline materials. In this work, electrochemical sensors for Cr(VI) detection in a wide pH range were explored, providing important guidance for the design of efficient electrochemical sensors for ultra-trace detection of heavy metal ions in practical environments.

Disease-associated metabolic pathways affected by heavy metals and metalloid

Increased exposure to environmental heavy metals and metalloids and their associated toxicities has become a major threat to human health. Hence, the association of these metals and metalloids with chronic, age-related metabolic disorders has gained much interest. The underlying molecular mechanisms that mediate these effects are often complex and incompletely understood. In this review, we summarize the currently known disease-associated metabolic and signaling pathways that are altered following different heavy metals and metalloids exposure, alongside a brief summary of the mechanisms of their impacts. The main focus of this study is to explore how these affected pathways are associated with chronic multifactorial diseases including diabetes, cardiovascular diseases, cancer, neurodegeneration, inflammation, and allergic responses upon exposure to arsenic (As), cadmium (Cd), chromium (Cr), iron (Fe), mercury (Hg), nickel (Ni), and vanadium (V). Although there is considerable overlap among the different heavy metals and metalloids-affected cellular pathways, these affect distinct metabolic pathways as well. The common pathways may be explored further to find common targets for treatment of the associated pathologic conditions.

Toxicity Characterization of Environment-Related Pollutants Using a Biospectroscopy-Bioreporter-Coupling Approach: Potential for Real-World Toxicity Determination and Source Apportionment of Multiple Pollutants

Exposure to environmental pollutants occurs ubiquitously and poses many risks to human health and the ecosystem. Although many analytical methods have been developed to assess such jeopardies, the circumstances applying these means are restricted to linking the toxicities to compositions in the pollutant mixtures. The present study proposes a novel analytical approach, namely, biospectroscopy-bioreporter-coupling (BBC), to quantify and apportion the toxicities of metal ions and organic pollutants. Using a toxicity bioreporter ADPWH_recA and Raman spectroscopy, both bioluminescent signals and spectral alterations had similar dosage- and time-response behavior to the toxic compounds, validating the possibility of coupling these two methods from practical aspects. Raman spectral alterations successfully distinguished the biomarkers for different toxicity mechanisms of individual pollutants, such as ring breathing mode of DNA/RNA bases (1373 cm^-1) by Cr, reactive oxygen species-induced peaks of proteins (1243 cm^-1), collagen (813 cm^-1), and lipids (1255 cm^-1) by most metal ions, and indicative fingerprints of organic toxins. The support vector machine model had a satisfactory performance in distinguishing and apportioning toxicities of individual toxins from all input data, achieving a sensitivity of 88.54% and a specificity of 97.80%. This work set a preliminary database for Raman spectral alterations of whole-cell bioreporter response to multiple pollutants. It proved the state-of-the-art concept that the BBC approach is feasible to rapidly quantify and precisely apportion toxicities of numerous pollutant mixtures.

Perspectives of nanomaterials in microbial remediation of heavy metals and their environmental consequences: A review

Nanomaterials (NMs) have diverse applications in various sectors, such as decontaminating heavy metals from drinking water, wastewater, and soil. Their degradation efficiency can be enhanced through the application of microbes. As microbial strain releases enzymes, which leads to the degradation of HMs. Therefore, nanotechnology and microbial-assisted remediation-based methods help us develop a remediation process with practical utility, speed, and less environmental toxicity. This review focuses on the success achieved for the bioremediation of heavy metals by nanoparticles and microbial strains and in their integrated approach. Still, the use of NMs and heavy metals (HMs) can negatively affect the health of living organisms. This review describes various aspects of the bioremediation of heavy materials using microbial nanotechnology. Their safe and specific use supported by bio-based technology paves the way for their better remediation. We discuss the utility of nanomaterials for removing heavy metals from wastewater, toxicity studies and issues to the environment with their practical implications. Nanomaterial assisted heavy metal degradation coupled with microbial technology and disposal issues are described along with detection methods. Environmental impact of nanomaterials is also discussed based on the recent work conducted by the researchers. Therefore, this review opens new avenues for future research with an impact on the environment and toxicity issues. Also, applying new biotechnological tools will help us develop better heavy metal degradation routes.

Bioreduction of Cr(VI) using a propane-based membrane biofilm reactor

The strong physiological toxicity of Cr(VI) makes it widely concerned in wastewater treatment. At present, the simplest and harmless method for treating Cr(VI) is known to be biologically reducing it to Cr(III), making it precipitate as Cr(OH)₃(s), and then removing Cr(III) by solid separation technology. Studies have shown that Cr(VI) reduction bacteria can use CH₄ and H₂ as electron donors to reduce Cr(VI). Based on this, in this study, C₃H₈ was used as the only electron donor to investigate the potential of C₃H₈ matrix membrane bioreactor in the Cr(VI) wastewater treatment. The experiment was divided into three stages, each of which run stably for at least 30 days, and the whole process run for 120 days in total. The experiment is divided into three stages, each stage runs stably for at least 30 days, for a total of 120 days. With the increase of the Cr(VI) load, the removal rate gradually decreased. In stage 3, when Cr(VI) concentration was 2.0 mg·L^-1, the removal rate was reduced from 90% in the first stage to 75%. According to X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis, it is known that Cr(III) is the main product during this process and it is adsorbed on the biofilm as Cr(OH)₃ precipitate. During the experiment, the amount of extracellular polymeric substance (EPS) produced by microorganisms increased initially and then decreased, and the amount of polysaccharides (PS) was always more than protein (PN). By analyzing the microbial community structure after inoculating sludge and adding Cr(VI), Nocardia and Rhodococcus dominate the biofilm samples. Chromate reductase, cytochrome c, nitrate reductase, and other functional genes related to chromate reductase increased gradually during the experiment.

Chromium toxicity and tolerance mechanisms in plants through cross-talk of secondary messengers: An overview of pathways and mechanisms

Environmental sources of chromium (Cr) such as solid waste, battery chemicals, industrial /waste, automotive exhaust emissions, mineral mining, fertilizers, and pesticides, have detrimental effects on plants. An excessive amount of Cr exposure can lead to toxic accumulations in human, animal, and plant tissues. In plants, diverse signaling molecules like hydrogen sulfide (H₂S) and nitric oxide (NO) play multiple roles during Cr stress. Consequently, the molecular mechanisms of Cr toxicity in plants, such as metal binding, modifying enzyme activity, and damaging cells are examined by several studies. The reactive oxygen species (ROS) that are formed when Cr reacts with lipids, membranes, DNA, proteins, and carbohydrates are all responsible for damage caused by Cr. ROS regulate plant growth, programmed cell death (PCD), cell cycle, pathogen defense, systemic communication, abiotic stress responses, and growth. Plants accumulate Cr mostly through the root system, with very little movement to the shoots. The characterization of stress-inducible proteins and metabolites involved in Cr tolerance and cross-talk messengers has been made possible due to recent advances in metabolomics, transcriptomics, and proteomics. This review discusses Cr absorption, translocation, subcellular distribution, and cross-talk between secondary messengers as mechanisms responsible for Cr toxicity and tolerance in plants. To mitigate this problem, soil-plant systems need to be monitored for the biogeochemical behavior of Cr and the identification of secondary messengers in plants.

Highly Selective MOF-Based Turn-Off Luminescence Detection of Hg2+ Ions in an Aqueous Medium and Its Dual Functional Catalytic Activity toward Aldol Condensation and β-Enamination Reactions

A new organic ligand, 5-(carboxyformamido)isophthalic acid (5-CFIA), was prepared and employed for the synthesis of two compounds [M₃(C₁₀H₄O₇N₁)₂(8H₂O)]·H₂O (M = Cd, Mn). The compounds have three-dimensionally extended structures. Both the compounds were found to be luminescent at room temperature. The luminescence nature was exploited for the detection of Hg²⁺ ions in an aqueous medium with good selectivity. The interactions between Hg²⁺ ions and the compounds quench the luminescence intensity and act as a turn-off sensor. Both the compounds exhibited low limits for the detection of Hg²⁺ ions and in the range mandated by the WHO. The interactions between Hg²⁺ ions and the compound involve the -NH group, which was probed using Raman and IR spectroscopic techniques. These studies provide important pointers toward the mechanism of this turn-off luminescence behavior. The compounds were explored for base-catalyzed aldol condensation and Lewis acid-promoted β-enaminoester formation reactions. The aldol condensation reaction uses the -NH functionality as a base. The studies indicate that the electron-withdrawing group produces products with higher yields. The β-enaminoester reaction uses the Lewis acid centers, and the studies reveal that the electron-withdrawing groups produce lesser yields of the products. The catalytic nature of the reaction and recyclability of the catalysts were also established. The catalytic reactions employ ethanol (aldol condensation) and no solvent (β-enaminoester), which suggests that the reactions are green and environmentally friendly. The Mn compound was observed to be anti-ferromagnetic.

Pollution characteristics and risk assessment of potentially toxic elements of fine street dust during COVID-19 lockdown in Bangladesh

Due to the COVID-19 pandemic, Bangladesh government took the measure like partial lockdown (PL) and complete lockdown (CL) to curb the spread. These measures gave a chance for environmental restoration. In this study, street dust samples were collected during PL and CL from four main urban land use categories in Dhaka city, such as industrial area (IA), commercial area (CA), public facilities area (PFA), and residential area (RA). Ten potentially toxic elements (Cr, Mn, Zn, Fe, Pb, Cu, Co, Ni, As, and Cd) in fine street dust particles (diameter < 20 μm) were determined following aqua-regia digestion and measured by inductively coupled plasma mass spectrometry (ICP-MS) to evaluate distribution, pollution sources, and potential risks to ecological systems and human health. Results showed that during PL, the concentrations of toxic elements in the dust were higher than that of CL. Cd and Fe were lowest and highest in concentration with 1.56 to 41,970 µg/g and 0.82 to 39,330 µg/g in partial and complete lockdown period respectively. All toxic elements were detected at high levels above background values where Fe with the highest and Cd with lowest concentrations, respectively. By land use, the levels of toxic elements pollution followed IA > PFA > RA > CA. Correlation analysis (CA), principal component analysis (PCA), and hierarchal cluster analysis (HCA) revealed that the sources of these analyzed toxic elements were mainly from anthropogenic which are related to industrial and vehicular or traffic emissions. Enrichment factor (EF), geoaccumulation index (I_geo), contamination factor (CF), and pollution load index (PLI) also suggested that the dust was more polluted during PL. Exposure of toxic elements to human was mainly via skin contact followed by ingestion and inhalation. Hazard quotient (HQ) values were < 1 except for Mn through dermal contact at all sites during partial and complete lockdown, similar to hazard index (HI), while Cr further showed high non-carcinogenic risks to children. Generally, children HI values were about 5-6 times higher than those of adults, suggesting a greater vulnerability of children to the health concerns caused by toxic elements in street dust. Carcinogenic risk (CR) values via ingestion pathway indicated all elements (except Pb) had significant health effect, while CR value by inhalation results showed no significant health effect. Cumulative carcinogenic risk (CCR) value had significant health effect except Pb in all land use categories. CCR values decreased during CL and reached at acceptable limit for most of the cases. This research provides a message to the local governments and environmental authorities to have a complete assessment of toxic elements in the street dust of Dhaka megacity in order to assuring public health safety and ecological sustainability.

The Potential Contribution of Hexavalent Chromium to the Carcinogenicity of Chrysotile Asbestos

Chrysotile asbestos is a carcinogenic mineral that has abundantly been used in industrial and consumer applications. The carcinogenicity of the fibers is partly governed by reactive Fe surface sites that catalyze the generation of highly toxic hydroxyl radicals (HO^•) from extracellular hydrogen peroxide (H₂O₂). Chrysotile also contains Cr, typically in the low mass permille range. In this study, we examined the leaching of Cr from fibers at the physiological lung pH of 7.4 in the presence and absence of H₂O₂. Furthermore, we investigated the potential of cells from typical asbestos-burdened tissues and cancers to take up Cr leached from chrysotile in PCR expression, immunoblot, and cellular Cr uptake experiments. Finally, the contribution of Cr to fiber-mediated H₂O₂ decomposition and HO^• generation was studied. Chromium readily dissolved from chrysotile fibers in its genotoxic and carcinogenic hexavalent redox state upon oxidation by H₂O₂. Lung epithelial, mesothelial, lung carcinoma, and mesothelioma cells expressed membrane-bound Cr(VI) transporters and accumulated Cr up to 10-fold relative to the Cr(VI) concentration in the spiked medium. Conversely, anion transporter inhibitors decreased cellular Cr(VI) uptake up to 45-fold. Finally, chromium associated with chrysotile neither decomposed H₂O₂ nor contributed to fiber-mediated HO^• generation. Altogether, our results support the hypothesis that Cr may leach from inhaled chrysotile in its hexavalent state and subsequently accumulate in cells of typically asbestos-burdened tissues, which could contribute to the carcinogenicity of chrysotile fibers. However, unlike Fe, Cr did not significantly contribute to the adverse radical production of chrysotile.

Multivariable modeling, optimization and experimental study of Cr(VI) removal from aqueous solution using peanut shell biochar

Peanut shell biomass was selected and utilized to produce biochar through pyrolysis under N₂ atmosphere at 923 K. After studying various effects of experimental parameters and by statistical modeling and optimization by RSM using Box-Benken design, optimized conditions of pH 2.0 ± 0.1, temperature 303 K, and adsorbent dose used of 2.5 g L^-1 were obtained giving almost 99.99% removal for Cr(VI) from the solution. FESEM, FTIR, XRD, XPS, EDX, elemental mapping, and pH_zpc were used for the evaluation of the surface characteristics of peanut shell biochar (PSB). Studies revealed C-O, C-H, CO, and O-H functional groups' presence with the help of FTIR, majorly in control of adsorption mechanism and the EDX confirmed the presence of Cr(VI) onto peanut shell biochar (PSB). Further adsorption mechanism for Cr(VI) adsorption followed the pseudo-second-order rate with adsorption capacity of 29.38 mg g^-1 given by the Langmuir isotherm. The thermodynamic study confirmed the exothermic and spontaneous nature of the process for Cr(VI) adsorption onto PSB. The adsorption mechanism showed electrostatic attraction, reduction, and complexation mainly responsible for Cr(VI) adsorption by PSB. Thus, PSB effectively removes Cr(VI) is confirmed by the present study.

A Comparative Study of Chromium: Therapeutic Uses and Toxicological Effects on Human Health

Chromium is an essential trace element whose deficiency can cause impairment of glucose tolerance, growth and various biological functions. There are two isotopes of chromium-trivalent chromium and hexavalent chromium. Both the isotopes of chromium have quite different effects on the human body. The objective of this narrative review is to compile the different effects of the two isotopes of chromium and give a comprehensive analysis of the effects of hexavalent and trivalent chromium. Data from various studies across different forums were compared to provide a concrete analysis of the therapeutic and harmful effects of two isotopes of chromium on human health. Chromium plays a vital role in the biological functions of the body. It might be helpful in balancing the glycaemic levels, triglyceride levels and cholesterol levels in the body. Excessive intake of chromium is harmful for health. Overexposure to chromium can lead to carcinogenic effects. Consumption of an insufficient amount of chromium might not be adequate as well. Trivalent chromium can be quite beneficial if taken in proper quantities. Hexavalent chromium can cause cancer. Trivalent chromium is beneficial, while hexavalent chromium is harmful to human health.

A Highly Selective MOF-Based Probe for Turn-On Luminescent Detection of Al3+, Cr3+, and Fe3+ in Solution and Test Paper Strips through Absorbance Caused Enhancement Mechanism

Trivalent metal ions (Cr³⁺, Al³⁺, and Fe³⁺) constitute a major section of the environmental pollutants, and their excess accumulation has a detrimental effect on health, so their detection in trace quantity has been a hot topic of research. A highly scalable 3D porous Zn-based luminescent metal-organic framework (MOF) has been synthesized by exploiting the mixed ligand synthesis concept. The strategic selection of an aromatic π-conjugated organic linker and N-rich spacer containing the azine functionality as metal ion binding sites immobilized across the pore spaces, have made this MOF an ideal turn-on sensor for Al³⁺, Cr³⁺, and Fe³⁺ ions with very high sensitivity, selectivity, and recyclability. An in-depth study revealed absorbance caused enhancement mechanism (ACE) responsible for such turn-on phenomena. In order to make the detection process straightforward, convenient, portable, and economically viable, we have fabricated MOF test paper strips (the MOF could be simply immobilized onto the paper strips) for naked eye visual detection under UV light, which, thus, manifests its potential as a real-time smart sensor for these trivalent ions.

A comprehensive review on human health effects of chromium: insights on induced toxicity

The growing use of heavy metals in most industrial activities has led to it being considered as the most important environmental pollutant that may cause harm and toxicity to animals and humans. Chromium has been found in the environment in different oxidation states such as Cr⁰, Cr(III), and Cr(VI) and is released from a variety of anthropogenic and natural activities. At among, trivalent and hexavalent chromium are the most stable forms. Considerably, Cr(VI) is frequently more toxic than Cr(III) because of its particular solubility and high mobility. Chronic exposure and bioaccumulation of chromium, as a heavy metal, can cause toxicity and numerous pathophysiological defects, including allergic reactions, anemia, burns, and sores especially in the stomach and small intestine, damage to sperm along with the male reproductive system, and affect various biological systems. Chromium pollution can have severe consequences for water and the soil environment. This article reviews the toxicological effects of Cr(VI) and Cr(III) and their mechanisms of toxicity and carcinogenicity.

On the Determination of Cr(VI) in Cr(III)-Rich Particulates: From the Failure of Official Methods to the Development of an Alternative Protocol

The goals of this work are the evaluation of the performances of official methods in the challenging determination of Cr(VI) in Cr(III)-rich particulate matter, and the development of a novel and robust analytical protocol for this issue. A liquid chromatography inductively coupled plasma mass spectrometry apparatus (LC-ICP-MS), together with an isotope-enriched spike addition technique, was used to allow the study of Cr(III)/Cr(VI) interconversions during the extraction step. An original separation strategy based on Cr(OH)₃ head-column stacking was developed to tolerate high concentrations of Cr(III) (up to 10 mg/kg, with a Cr(VI) limit of detection of 0.51 µg/kg) without the need of any sample pretreatment. After observing, the official extraction protocols always yield false positive values in the challenging situation of particulate matter of leather industries (where huge amounts of Cr(III) are present), a new extraction strategy was developed. The novel procedure involves a 48-h extraction at room temperature using a pH-8 phosphate buffer, which demonstrated that no Cr(III)/Cr(VI) interconversions occur during this phase. To get rid of any possible interference caused by co-extracted substances, the measurement of the redox potential, together with the addition of a Fe(II)/Fe(III) redox buffer was performed to fix chromium speciation during the overall analytical protocol.

Determination of some heavy metals and their health risk in T-shirts printed for a special program

Heavy metals often are used in different textile processes, like dyeing and printing. When the toxic elements are present in more than recommended in textile materials they may impose potential risk to human health by absorption through the skin. In this study concentrations of some heavy metals (Co, Cu, Cr, Cd, and Pb) were analyzed in skin contact fading T-shirts printed for a special program at Mettu town using Atomic Absorption Spectroscopy with a microwave digestion method technique for sample preparation. High levels of Cu were found in black, green, blue, and red-colored T-shirts ranging from 26.726–179.315mg/kg. Cr exceeded the recommended limits in most samples of T-shirts and was mostly in yellow, black, and blue colors. Cd levels were found to be within normal ranges. However, all T-shirt samples had low levels of cobalt, ranging from 1.33±2.13 to3.94±0.21. Maximum lead concentrations were found to be 3.40 ± 0.19 mg/kg for red-colored samples and 2.71 ± 0.13 mg/kg for blue colored samples. The metal concentrations in the T-shirts investigated were also compared to the OEKO Tex standard 100 limits. In this investigation, the concentrations of Pb, Cu, and Cr in red and green colored T-shirt samples were above the OEKO Tex suggested standard value. Therefore a strict local and international regulation and measures need to be taken to avoid toxicity of the studied metals.

A visual and reversible nanoprobe for rapid and on-site determination of hexavalent chromium and lysine based on dual-emission carbon quantum dots coupled with smartphone

A straightforward, largely instrument-free, smartphone-based analytical strategy for hexavalent chromium and lysine (Lys) on-site detection via exploitation of dual-emission carbon quantum dots (DECQDs) has been demonstrated. DECQDs show dual-emission peaks at 439 and 630 nm with the excitation at 375 nm. As a dual-mode detection probe, the fluorescence and ultraviolet adsorption spectra of DECQDs vary with hexavalent chromium concentrations. Most importantly, Lys can restore the fluorescence of the hexavalent chromium added DECQD nanoprobe and change the color of the probe under natural light. At the same time, based on the participation of smartphones, the prepared DECQD probes favor the establishment of visual smart sensors that can also be used for the in-situ detection of targets. The on-site quantitative analysis exhibited a linear range of 5.3-320 μM with a detection limit of 1.6 μM towards Cr(VI) and the differentiation of Lys variation from 1 to 75 mM with a detection limit of 0.3 mM. The probe has been applied for the first time to enable vision-based colorimetric in complex samples such as water, milk and egg. The recoveries of Cr(VI) and Lys in real samples were between 90 and 104%, and the relative standard deviation (RSD) was as low as 0.4%. This work offers new perspectives for fundamental understanding and new design of functional luminescent materials that are applicable for food-safety and rapid and intelligent inspection. A straightforward, large instrument-free, smartphone-based analytical strategy with dual-emission carbon quantum dots was developed for hexavalent chromium and Lys on-site detection via fluorescent and colorimetric twofold readout measure.

Water toxicants: a comprehension on their health concerns, detection, and remediation

Water is an essential moiety for the human use since a long time. Availability of good-quality water is very essential, as it is used in almost all the industrial, agricultural, and household activities. However, several factors such as increased urbanization and industrialization, extensive use of chemicals, natural weathering of rocks, and human ignorance led to incorporation of enormous toxicants into the water. The water toxicants are broadly classified as inorganic, organic, and radiological toxicants. Inorganic toxicants include heavy metals (As, Cr, Cd, Hg, Ni, Pb) and metalloids, ammonia, nitrate, and fluoride. Uranium is included in radiological toxicants which also causes chemical toxicity. Organic pollutants include polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phenolic compounds, phthalate esters, pesticides, pharmaceutical and personal care products, perchlorates, and flame retardants. These toxicants are harmful for the ecosystem as well as for the human beings causing different types of health complications like lung cancer, nasal cancer, gingivitis, severe vomiting and abdominal pain, hormonal imbalance, skeletal damage, neurotoxicity like Alzheimer and Parkinson disease, renal toxicity, nephrotoxicity, etc. The USEPA and WHO specified the permissible concentration of these pollutants in the drinking water. Determination techniques having high sensitivity, low cost, rapid onsite, and real-time detection of traces of water pollutants are discussed. This review also covers in depth about the remediation techniques, for the control of water toxicants, such as chelation of the heavy metals, intoxication of pollutants using various plants, adsorption of toxicants using different sorbent medias, and photocatalytic breakdown of persistent organic pollutants (POPs).

Reviewing variables and their implications affecting adsorption of Cr(VI) onto activated carbon: an in-depth statistical case study

Removal of Cr(VI) from the aqueous phase using numerous activated carbons (AC) has been broadly studied in the last decades. Nevertheless, the diversity of activation methods, AC properties, and adsorption conditions precludes the standardization of specific characteristics required to achieve better adsorption results. This work reviewed the pertinent literature on Cr(VI) adsorption onto AC published over the past four decades. Pearson's correlation matrix and principal component analysis (PCA) assisted in identifying the parameters and AC characteristics that have the greatest influence on the maximum adsorption capacity (q_m). Two hundred thirty-six adsorption assays were found reporting data on 110 ACs and different parameters. Of these, 39.8% of the studies contemplated the variables q_m, pH, temperature (T), surface area (S_BET), micropore volume (V_micro), and mesopore volume (V_meso), and only 19.5% reported the point of zero charge (pH_PZC). Statistical analysis disclosed that S_BET and V_micro have a strong positive correlation with q_m, while V_meso, T, and pH show little or no correlation. The difference between pH and pH_PZC (PZC_diff) indicated a significant anticorrelation with q_m, thus evidencing that lower PZC_diff values enhance adsorption. The findings are useful for all researchers that work with Cr(VI) adsorption on AC since they provide a start point concerning the required adsorbent characteristics and process conditions to be employed.

Disaster Risk Management, Ventilated Improved Pit Latrines, and Sanitation Challenges in South Africa

The current paper provides a review and meta-analysis of the practical implications of disaster risk management related to the ventilated improved latrines in South Africa. This technology is evaluated through its legacy and novel challenges of disaster risk reduction. In the current article, the methodology adopted was a literature review and meta-analyses. The results indicate that the in-situ treatment and breakdown of faecal sludge in the ventilated improved pit latrines is not always taking place and that anaerobic digestion might not always be feasible. New strategies are proposed to manage the sanitation-related risks in South Africa by specifying more exact dimensions for the newly built ventilated improved pit latrines by suggesting the use of novel sanitation additives such as fly ash to enhance on-site and in situ treatment, as well as ex situ treatment of the pit latrine faecal sludge. Regular maintenance can lead to prevention of the dysfunctional character of the ventilated improved pit latrines as a functional sanitation technology and a user-friendly hygiene barrier to the spread of sanitation/WASH-related epidemics or infectious diseases. The implementation of the novel strategies should be enhanced by the application of the (Environmental) Technology Assessment in sanitation service delivery in South Africa.

Metal biomonitoring using fractioned dust to investigate urinary and oxidative stress biomarkers among occupationally exposed chromite mine workers

Exposure to heavy metals has been associated with the generation of reactive oxygen species (ROS) among exposed individuals in occupational and environmental settings. Dust is considered a significant contributor to airborne metal exposure, and previous data suggest that their levels in dust may vary based on its particle sizes. However, no biomonitoring study has been reported so far to address the metal-induced oxidative stress using different dust fractions, particularly in occupational settings. We designed a systematic cross-sectional study involving 110 chromite mine workers stratified into loaders (n = 28), extractors (n = 47) and operators (n = 35), and controls (n = 30) to find out the association between dust-bound metal exposure and oxidative stress using urinary creatinine-adjusted metal level as a biomarker of metal exposure. Results suggested elevated urinary levels of Cr 51.34 ± 8.6 along with Pb 34.29 ± 4.39, Cd 21.1 ± 2.6, and Ni 18.98 ± 3.01 µg/g creatinine in exposed (extractor group) workers. Correlating metal levels with oxidative stress revealed elevated malondialdehyde (MDA) levels of 62.28 ± 5.52 nM/dl among the extractors showing high levels of lipid peroxidation. Furthermore, blood superoxide dismutase (SOD) was also found significantly correlated (P = 0.000) with urinary toxic metal levels among exposed workers. We report the association between metal exposure and oxidative stress in exposed mining workers that may give rise to workers' susceptibility towards genetic and non-genetic health implications. The current study emphasized on the need for exposure control measures in the chromite ore mining activity areas.

The Content and Toxicological Risk Assessment of Trace Elemental Impurities (Pb and Cr) in Snacks from Ogun State, Southwestern Nigeria

The monitoring of food contamination by trace elemental impurities (TEIs) are major health challenges in developing countries. The present study evaluated the content and toxicological risk assessment of TEIs in commonly consumed snack/junk foods from Ogun State, Nigeria. TEIs (Pb and Cr) were determined in sixty snack food samples purchased from Ijebu Ode, Ogun State, southwestern Nigeria. The TEIs were analysed in quadruplicates using atomic absorption spectrometry with flame atomization. TEI data were subjected to simple descriptive and inferential statistics. The toxicological risk assessment of TEIs was evaluated for hazard quotient (HQ), hazard index (HI) and cancer risk (CR) using the United States Environmental Protection Agency-Integrated Risk Information System (USEPA-IRIS) model. Data showed the varying Pb levels of 8.22 ± 1.57 mg/kg in sausage to 12.25 ± 4.27 mg/kg in cocoyam chips higher than the permissible limit of the Codex Alimentarius of the Joint World Health Organization and Food and Agriculture Organization. The toxicological risk assessment revealed the HQs greater than 1.0 for Pb and Cr in most snack foods consumed by adults and children, indicating adverse health problems. The CRs of Pb (children) and Cr (adults and children) also breached the acceptable limit of 1.0 × 10^-4, signifying possible lifetime development of cancer. It is therefore necessary to periodically monitor the TEIs in snacks to protect the public health.

The effects of soil organic matter on leaching of hexavalent chromium from concrete waste: Batch and column experiments

Concrete is one of the most common building materials in the world and in accordance with the world's shift to a circular economy, there is a need of an increase in concrete reuse and recycling. One of the environmental concerns linked to concrete recycling is the leaching and spread of hexavalent chromium (Cr(VI)). In the present study the Cr(VI) leaching from crushed concrete waste and the effects of soil organic matter (SOM) on chromium (Cr) speciation has been investigated in realistic reuse scenarios by the means of batch shale tests and layered column tests. The effects of concrete properties (pH, grain size and age) on Cr(VI) leaching was also studied. Cr leaching from concrete alone is mainly in the form of Cr(VI), with the pH of the leachate being >10. The smaller the grainsize of the concrete, the higher the Cr(VI) concentration is in the leachate. There was no correlation between the age of the concrete and concrete leaching. When exposed to SOM the Total-Cr concentration in the leachate was reduced. The reduction increased with higher TOC level, with a 99% reduction at very high TOC (25%). The results indicate that Cr(VI) leaching from recycled concrete waste can be mitigated by exposing it to SOM in the desired recycling scenario.

A Comparative Analysis of Heavy Metal Effects on Medicinal Plants

Popularity of herbal drugs has always been in high demand, but recently it has been increasing all over the world, especially in India, because of the lower range of adverse health effects as compared to synthetic or man-made drugs. Not only this but their cost-effectiveness and easy availability to the poor people and the masses, particularly in developing countries, are major causes for their demand. But there lies a huge problem during the process of plant collection that affects their medicinal properties to certain degrees. This is caused by heavy metal toxicity in soil in different locations of the Indian subcontinent. This was correlated with their potential to cause health damage. Exposure of humans to heavy metals includes diverse pathways from food to water to consumption and inhalation of polluted air to permanent damage to exposed skin and even by occupational exposure at workplaces. As we can understand, the main mechanisms of heavy metal toxicity include the production of free radicals to affect the host by oxidative stress, damaging biological molecules such as enzymes, proteins, lipids, and even nucleic acids and finally damaging DNA which is the fastest way to carcinogenesis and in addition, neurotoxicity. Therefore, in this paper, we have researched how the plants/herbs are affected due to heavy metal deposition in their habitat and how it can lead to serious clinical complications.

Toxicity and Metabolomic Impact of Cobalt, Chromium, and Nickel Exposure on HepaRG Hepatocytes

Cobalt, chromium, and nickel are used in orthopedic prostheses. They can be released, accumulate in many organs, and be toxic. The aim of this study is to evaluate the cytotoxicity of these metals on human hepatocytes and to improve our knowledge of their cellular toxicity mechanisms by metabolomic analysis. HepaRG cells were incubated for 48 h with increasing concentrations of metals to determine their IC₅₀. Then, a nontargeted metabolomic study using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) was done at IC₅₀ and at a lower concentration (100 nM), near to those found in the blood and liver of patients with prostheses. IC₅₀ were defined at 940, 2, and 1380 μM for Co, Cr, and Ni, respectively. In vitro, Cr appears to be much more toxic than Co and Ni. Metabolomic analysis revealed the disruption of metabolic pathways from the low concentration of 100 nM, in particular tryptophan metabolism and lipid metabolism illustrated by an increase in phenylacetylglycine, a marker of phospholipidosis, for all three metals. They also appear to be responsible for oxidative stress. Dysregulation of these pathways impacts hepatocyte metabolism and may result in hepatotoxicity. Further investigations on accessible biological matrices should be conducted to correlate our in vitro results with the clinical data of prostheses-bearing patients.

HBM4EU Chromates Study: Urinary Metabolomics Study of Workers Exposed to Hexavalent Chromium

Exposure to hexavalent chromium Cr(VI) may occur in several occupational activities, placing workers in many industries at risk for potential related health outcomes. Untargeted metabolomics was applied to investigate changes in metabolic pathways in response to Cr(VI) exposure. We obtained our data from a study population of 220 male workers with exposure to Cr(VI) and 102 male controls from Belgium, Finland, Poland, Portugal and the Netherlands within the HBM4EU Chromates Study. Urinary metabolite profiles were determined using liquid chromatography mass spectrometry, and differences between post-shift exposed workers and controls were analyzed using principal component analysis. Based on the first two principal components, we observed clustering by industrial chromate application, such as welding, chrome plating, and surface treatment, distinct from controls and not explained by smoking status or alcohol use. The changes in the abundancy of excreted metabolites observed in workers reflect fatty acid and monoamine neurotransmitter metabolism, oxidative modifications of amino acid residues, the excessive formation of abnormal amino acid metabolites and changes in steroid and thyrotropin-releasing hormones. The observed responses could also have resulted from work-related factors other than Cr(VI). Further targeted metabolomics studies are needed to better understand the observed modifications and further explore the suitability of urinary metabolites as early indicators of adverse effects associated with exposure to Cr(VI).

Effectiveness of Direct Laser Interference Patterning and Peptide Immobilization on Endothelial Cell Migration for Cardio-Vascular Applications: An In Vitro Study

Endothelial coverage of an exposed cardiovascular stent surface leads to the occurrence of restenosis and late-stent thrombosis several months after implantation. To overcome this difficulty, modification of stent surfaces with topographical or biochemical features may be performed to increase endothelial cells’ (ECs) adhesion and/or migration. This work combines both strategies on cobalt-chromium (CoCr) alloy and studies the potential synergistic effect of linear patterned surfaces that are obtained by direct laser interference patterning (DLIP), coupled with the use of Arg-Gly-Asp (RGD) and Tyr-Ile-Gly-Ser-Arg (YIGSR) peptides. An extensive characterization of the modified surfaces was performed by using AFM, XPS, surface charge, electrochemical analysis and fluorescent methods. The biological response was studied in terms of EC adhesion, migration and proliferation assays. CoCr surfaces were successfully patterned with a periodicity of 10 µm and two different depths, D (≈79 and 762 nm). RGD and YIGSR were immobilized on the surfaces by CPTES silanization. Early EC adhesion was increased on the peptide-functionalized surfaces, especially for YIGSR compared to RGD. High-depth patterns generated 80% of ECs’ alignment within the topographical lines and enhanced EC migration. It is noteworthy that the combined use of the two strategies synergistically accelerated the ECs’ migration and proliferation, proving the potential of this strategy to enhance stent endothelialization.