Arsenic Acid Research Articles

Pharmacognostical Assessment, Antioxidant Ability and Determination of Phytomolecules using GC-MS in Gloriosa superba Linn.

Gloriosa superba Linn (family Colchicaceae) is a tendril climber with cylindrical and V or L shaped rhizomes that has received much attention due to its ancient pharmacological uses and being a rich source of colchicine. The pharmacognostical profile of leaf, stem and rhizome were analysed to assure the grade of raw material in the proposed investigation. Moreover, the antioxidant capacity of ethanolic rhizome extract of G. superba (EREG) was assessed using DPPH radical scavenging assay. Simultaneously, we have evaluated the phytochemical profile of EREG by GC-MS and total phenolic content was performed as well. Transverse section (TS) of rhizome revealed thin layer of brownish scales that fabricate the outer skin. In addition, the cortical area made up of homogeneous fleshy and parenchymal cells filled with starch granules which is one of the superabundant diagnostic features of this plant. Pharmacognostical profile of leaf, stem and rhizome of the plant demonstrated the evidence of authenticity of this plant. Anti-scavenging capacity (IC50) and total phenolic content was 77.20% and 9.54 mg, GAE/g, respectively. The GC-MS library identified two phytoconstituents as diethyl phthalate (100% peak area) and arsenous acid, tris(trimethylsilyl) ester (22.68% peak area) whose vast benefits are reported in the fields of pharmaceuticals, industry and personal care products. Frivolous research work in the field of pharmacognosy, antioxidant ability and instrumental analysis for phytomolecules provides a vast avenue for research on G. superba.

Exposure to arsenic, polycyclic aromatic hydrocarbons, metals, and association with skin cancers in the US adults.

Worldwide, skin cancer affects millions of people yearly and is broadly classified into melanoma and nonmelanoma types of skin cancer. The toxicity of metals to human health is a public and clinical health problem due to their widespread use in tools, machinery, and appliances as well as their widespread distribution in the air, water, and soil. Arsenic is a carcinogenic metalloid and available in the Earth's crust. Polycyclic aromatic hydrocarbons (PAHs) are toxic to humans, and incomplete combustion of fossil fuels is the main source of PAHs. Human populations exposed to metals from various sources can lead to various diseases including cancer. Limited studies are conducted to simultaneously assess the correlation of multiple arsenic, PAHs, metals with the occurrence of skin cancer. This study aimed to analyze the association between six PAHs compounds, seven types of arsenic, and fourteen metals from urine specimen with skin cancer in US adults. We performed a cross-sectional analysis using data from a total of 14,716 adults from the National Health Examination and Nutrition Survey (NHANES) database for three cycles ranging from 2011-2012 to 2015-2016. Specialized weighted complex survey logit regressions were conducted. Linear logit regression models using only main effects were performed first to identify the correlation between the selected demographic and lifestyle variables and melanoma, nonmelanoma, and unknown types of skin cancer. A second set of linear, main-effects logit regression models were constructed to examine the correlation between melanoma, nonmelanoma, and other types of skin cancers and seven types of arsenic (arsenous acid, arsenic acid, arsenobetaine, arsenocholine, dimethylarsinic acid, monomethylacrsonic acid, and total arsenic), six PAHs (1-hydroxynaphthalene, 2-hydroxynaphthalene, 3-hydroxyfluorene, 2-hydroxyfluorene, 1-hydroxyphenathrene, and 1-hydroxypyrene), and fourteen metals (barium, cadmium, cobalt, cesium, molybdenum, manganese, lead, antimony, tin, strontium, thallium, tungsten, uranium, and mercury) when adjusted for the selected covariates. The statistical analysis was conducted using R software, version 4.0.4. A marginal positive significant correlation between total arsenic and nonmelanoma was observed. This study identified a significant positive association between barium, cadmium, cesium, mercury, tin, and melanoma development. Cesium showed a significant positive statistical association for nonmelanoma, and thallium showed a borderline significant statistical association for nonmelanoma. A statistically significant positive association was found between cadmium and an unknown type of skin cancer. The findings of this study indicated a statistically significant positive association between skin cancer and barium, cadmium, cesium, tin, mercury, and thallium. Further studies are recommended in humans to refute or confirm these findings.

Stable and efficient As2O3 removal from simulated flue gas using Al2O3/CaSiO3 prepared by anhydrous grinding and calcination method

CaSiO3 exhibits good arsenic capture performance, but it falls short of meeting the actual needs of power plants due to its susceptibility to acidic gases that inhibit its arsenic capture ability. In this study, an Al2O3/CaSiO3 adsorbent was prepared by combining the anhydrous grinding and calcining methods. Arsenic vapor capture was conducted in flue gas containing or free of SO2 and HCl within the temperature range of 800–1000 ℃. The research indicated that the preparation method used in this study resulted in uniform Al2O3 doping that was less prone to agglomeration, thereby creating a good pore structure. The Al2O3/CaSiO3 adsorbent exhibited the strongest arsenic capture capacity when the atomic molar ratio of Al/Si was 1:5, with an arsenic capture amount of 871.2 mg/kg, which was significantly higher than the capture capacity of the control group calcium silicate. The doping of Al atoms altered the structure and charge distribution of CaSiO3 silica-oxygen chains, resulting in the formation of Al active sites with higher adsorption energy, which is more favorable for the adsorption of arsenic. Although the Al2O3/CaSiO3 adsorbent reacts with acidic gases to form CaSO4 and CaCl2, which can inhibit arsenic capture, it still maintains a high arsenic capture rate. Al2O3/CaSiO3 has excellent arsenic removal, sintering resistance, and acid resistance, making it a promising composite adsorption material for arsenic removal.

Evaluation of azo dyes degradation potential of fungal strains and their role in wastewater treatment

In the present investigation, two fungal strains were exploited to evaluate their degradation capability on Synozol Red, Yellow, and Navy-Blue dyes which gave the utmost decolorization such as 40%, 70%, 90% by Aspergillus niger, and 36%, 73%, 87% by Trichoderma viride, respectively for 60 days. The Gas Chromatography-Mass Spectrometry (GC–MS) analysis of the decolorized dyes suggested that various compounds such as Caprolactam, Furazan-3-carboxamide, oxime, 4-amino-N, N-dimethyl, 6H-Pyrazolo[1,2-a] [1,2,4,5]tetrazine, Hexahydro-2,3-dimethyl, Benzene, 1-propenyl, Dihydroxymaleic acid, Arsenous acid, tris(trimethylsilyl) ester were produced by the fungi which helped in the removal of dyes from the wastewater. The laccase activity of the degraded dyes was proof that both of the strains positively produced the enzyme that helped in the biodegradation of carcinogenic dyes into less harmful products. The A. niger extracted laccase relative activity was 262%, 265%, and 145.7% for Synozol Yellow, Synozol Red, and Navy Blue, respectively. Similarly, laccase, obtained from T. viride, showed relative activity of 187.5% against Synozol Yellow, 215% against Synozol Red, and 202% against Navy Blue. Furthermore, the supernatant extracted from fungi-decolorized wastewater was used to check phytotoxicity on Vigna radiata, which gave excellent results. Both fungal strains, on the basis of their dye degradation potential, can be used to ameliorate wastewater contaminated with azo dyes.

Effects of Varied Forms of Arsenic Stress on Seedling Growth and Arsenic Distribution in Honeysuckle Plants

At present, soil arsenic contamination is one of the prominent environmental problems. The arsenic concentration in honeysuckle exceeds the standard levels, thus affecting the quality of traditional Chinese medicine. In this study, the hydroponic method was employed to explore the effect of organic arsenic (dimethyl arsenic) and trivalent inorganic arsenic (NaAsO2) on the growth of honeysuckle plants. The study demonstrated that low concentrations of inorganic arsenic (10–20 mg/L) and 10–50 mg/L organic arsenic had a stimulating effect on the growth of honeysuckle plants. The activities of antioxidant enzymes (peroxidase and catalase) increased correspondingly. However, the antioxidant system in honeysuckle plants was damaged under high concentrations of inorganic arsenic (20–40 mg/L) and 50–70 mg/L organic arsenic. On exposure to 30 mg/L NaAsO2 or 50 mg/L dimethyl arsenic acid for 10 days, the activities of peroxidase and catalase, as well as the malondialdehyde content, increased with prolonged exposure. The micro X-ray fluorescence analysis revealed that the accumulated arsenic in the roots was transported from the central vascular cylinders to the outer part of the root with the increase in concentration and exposure duration of inorganic arsenic. However, organic arsenic stress did not result in significant variations in the distribution of arsenic with increasing concentrations of arsenic. The arsenic element was predominantly located in the middle woody part of the root. The distributions of arsenic in the stems and leaves, in terms of organic and inorganic arsenic stresses, were similar, with accumulation primarily in the cortex of the stem and veins of the leaves. As a commonly used bulk traditional Chinese medicine, honeysuckle has a wide range of product quality issues. Hence, exploring the absorption, distribution, and transport trends of heavy metals such as arsenic in the plant body is of great significance for scientifically evaluating the impact of heavy metal pollution on the quality of medicinal materials and exploring ways to reduce the accumulation of heavy metals in the medicinal parts of plants.

Potential use of nanoparticles produced from byproducts of drinking water industry in stabilizing arsenic in alkaline-contaminated soils.

The stabilization of heavy metals in soils is considered a cost-effective and environmentally sustainable remediation approach. In the current study, the applicability of water treatment residual nanoparticles (nWTRs) with the particle size ranged from 45 to 96nm was evaluated for its efficacy in reducing arsenic mobility in clayey and sandy contaminated alkaline soils. Sorption isotherms, kinetics, speciation and fractionation studies were performed. Sorption equilibrium and kinetics studies revealed that As sorption by nWTRs-amended soils followed Langmuir and second-order/power function models. The maximum As sorption capacity (qmax) of Langmuir increased up to 21- and 15-folds in clayey and sandy soils, respectively, as a result of nWTRs application at 0.3% rate. A drastic reduction in non-residual (NORS) As fraction from 80.2 and 51.49% to 11.25 and 14.42% for clayey and sandy soils, respectively, at 0.3% nWTRs application rate was observed, whereas residual (RS) As fraction in both studied soils strongly increased following nWTRs application. The decline in percentage of As mobile form (arsenious acid) in both soils after nWTRs application indicated the strong effect of nWTRs on As immobilization in contaminated soils. Furthermore, Fourier transmission infrared spectroscopy analysis suggested reaction mechanisms between As and the surfaces of amorphous Fe and Al oxides of nWTRs through OH groups. This study highlights the effective management approach of using nWTRs as soil amendment to stabilize As in contaminated alkaline soils.

As3MT via consuming SAM is involved in arsenic-induced nonalcoholic fatty liver disease by blocking m6A-mediated miR-142-5p maturation

Arsenic, a common environmental hazard, is a risk factor for nonalcoholic fatty liver disease (NAFLD). However, the mechanism remains unclear. Here, we found that chronic exposure to environmental-related doses of arsenic disturbed fatty acid and methionine metabolism in mice, caused liver steatosis, increased arsenic (3) methyltransferase (As3MT), sterol regulatory element binding protein 1 (SREBP1) and lipogenic gene levels, and decreased N6-methyladenosine (m6A) and S-adenosylmethionine (SAM) levels. Mechanistically, arsenic blocks m6A-mediated miR-142-5p maturation by consuming SAM via As3MT. miR-142-5p was involved in arsenic-induced cellular lipid accumulation by targeting SREBP1. SAM supplementation or As3MT deficiency blocked arsenic-induced lipid accumulation by promoting the maturation of miR-142-5p. Moreover, in mice, folic acid (FA) and vitamin B12 (VB12) supplementation blocked arsenic-induced lipid accumulation by restoring SAM levels. Arsenic-exposed heterozygous As3MT mice showed low liver lipid accumulation. Our study demonstrates that SAM consumption caused by arsenic, through As3MT, blocks m6A-mediated miR-142-5p maturation, thereby elevating the levels of SREBP1 and lipogenic genes, leading to NAFLD, which provides a new mechanism and biological insights into the therapy of NAFLD induced by environmental factors.

Fertilization Enhances Grain Inorganic Arsenic Assimilation in Rice

To investigate how soil fertilization/amendments alters arsenic speciation grain off-take in paddy rice, rice was grown to maturity in growth chambers fertilized with standard mineral fertilizer, wood ash (rich in silica), pig slurry (rich in organic matter), and non-amended control. The soil was sourced from a Chinese paddy field. The primary fertilized elements (nitrogen, phosphorus, potassium) were kept constant across treatments. Porewater chemistry and soil microbiology were monitored throughout the experiments. Total grain arsenic, sum of inorganic arsenic and dimethylarsinic acid (DMA), was significantly different between treatments (P = 0.024), with inorganic arsenic varying from 0.025 to 0.08 mg/kg and DMA from 0.08 to 0.16 mg/kg for control compared to fertilized, respectively. Fertilizer source made no difference to arsenic speciation concentration in grain. Porewater analysis found that as anaerobism set in, inorganic arsenic, phosphorus and manganese greatly lowered in concentration. Methylated arsenic species concentrations increased over time, concurrent with an increase in pH, decrease in Eh, and increase in total organic carbon and iron, with no strong treatment effects, except for pig slurry that enhanced pH and decreased Eh. Methanogenic archaea, sulfate-reducing bacteria and Acidobacteria increased with time and some Actinobacteria and Firmicutes increased due to slurry, but then decreased with time (P < 0.01). Methanogenic archaea and sulphate-reducing bacteria correlated positively with porewater DMA and negatively with porewater inorganic arsenic (P < 0.05). Genera within the Actinobacteria and Burkholderiaceae correlated negatively with DMA, while genera with iron-reducing capacity (Clostridiales) correlated positively with porewater inorganic arsenic and DMA (P < 0.05).

Modulating the electronic structures derived by neighbouring hetero-diatomic FeCoN6-Gra for prominent electrocatalysis of arsenious acid

Single atom catalysts (SACs) have been widely studied in the field of electrocatalytic reduction, but in the complex multi-step proton-electron reactions, the metal active site is easy to be weakened or even poisoned. Therefore, how to improve the adsorption-desorption capacity and rapid surface reaction to obtain superior electrocatalytic performance remains a great challenge. We indicate the electron synergism of neighbouring Fe and Co diatoms on graphene (FeCoN6-Gra) to promote the electrocatalytic reduction of arsenious acid (As(III)), which is superior to single-atomic catalysts containing only Fe or Co. It is found that the new electron allocation mechanism associated with the injection of Co is beneficial to trigger the two-site adsorption and effectively regulate electron transport between surface sites and As(III). Moreover, the dynamic migration of As(III) driven by Co atom during the reduction process is emphasized, which contributes to break the As-O bond, thus achieving efficient catalysis of the diatomic model.

Structural assessment of OsNIP2;1 highlighted critical residues defining solute specificity and functionality of NIP class aquaporins

IntroductionNodulin-26-like intrinsic proteins (NIPs) are integral membrane proteins belonging to the aquaporin family, that facilitate the transport of neutral solutes across the bilayer. The OsNIP2;1 a member of NIP-III class of aquaporins is permeable to beneficial elements like silicon and hazardous arsenic. However, the atomistic cross-talk of these molecules traversing the OsNIP2;1 channel is not well understood. ObjectiveDue to the lack of genomic variation but the availability of high confidence crystal structure, this study aims to highlight structural determinants of metalloid permeation through OsNIP2;1. MethodsThe molecular simulations, combined with site-directed mutagenesis were used to probe the role of specific residues in the metalloid transport activity of OsNIP2;1. ResultsWe drew energetic landscape of OsNIP2;1, for silicic and arsenous acid transport. Potential Mean Force (PMF) construction illuminate three prominent energetic barriers for metalloid passage through the pore. One corresponds to the extracellular molecular entry in the channel, the second located on ar/R filter, and the third size constriction in the cytoplasmic half. Comparative PMF for silicic acid and arsenous acid elucidate a higher barrier for silicic acid at the cytoplasmic constrict resulting in longer residence time for silicon. Furthermore, our simulation studies explained the importance of conserved residues in loop-C and loop-D with a direct effect on pore dynamics and metalloid transport. Next we assessed contribution of predicted key residues for arsenic uptake, by functional complementation in yeast. With the aim of reducing arsenic uptake while maintaining beneficial elements uptake, we identified novel OsNIP2;1 mutants with substantial reduction in arsenic uptake in yeast. ConclusionWe provide a comprehensive assessment of pore lining residues of OsNIP2;1 with respect to metalloid uptake. The findings will expand mechanistic understanding of aquaporin’s metalloid selectivity and facilitate variant interpretation to develop novel alleles with preference for beneficial metalloid species and reducing hazardous ones.

First principles investigation on adsorption mechanism of As(OH)3 on the kaolinite (001) surface

The environmental fate of arsenic (As) and arsenic-containing compounds are garnering more attention as a result of the global As contamination. Arsenous acid (As(OH)3) exists as a common arsenic-containing compound in the aqueous phase. Natural clay minerals like kaolinite have the potential to be adsorbents. First-principles calculations based on DFT were used to investigate the adsorption mechanism between As(OH)3 molecules and the kaolinite (001) surface. The two-fold bridge sites of the kaolinite (001) surface were found to be most stable for As(OH)3 adsorption. Three representative stable adsorption configurations, B2, H6, and T3, were selected to analyze. Strong hydrogen bonds formed between As(OH)3 molecules and the kaolinite (001) surfaces made the main contribution to the adsorption. The coverage (Θ) dependence to the adsorption stability was methodically investigated with a wide coverage range of 0 < Θ ≤ 1.0 monolayers (ML). The adsorption energy of As(OH)3 increased in the coverage range of 0 < Θ ≤ 0.5 ML and then decreased in the coverage range of 0.5 < Θ ≤ 1.0 ML. Other properties of the As(OH)3/kaolinite (001) system, including the bonding interaction, atom population/charge, electronic density of states, and lattice relaxation were also discussed and analyzed in detail.

On the mechanism of the Tattersall test for morphine

Being morphine a restricted drug, a rapid colour test for its detection is very useful. Tattersall employed as reagent trisodium ortho-arsenate in sulphuric acid. However, the more common disodiumhydrogen ortho-arsenate heptahydrate can be used also because both salts yield the same reactive species, that is, protonated arsenic acid and a cation with arsenic(IV). An arsenate is formed with the phenolic group in morphine. Dehydration of this organometallic ester yields a cationic intermediate that induces reaction with arsenic acid at ortho-position (electromeric effect), and a concerted mechanism takes place. A dienone is formed and there is elimination of meta-arsenous acid. Aromatization followed by acidolysis of the new arsenate gives water, meta-arsenous acid, and morphine ortho-quinone, via a six-member concerted mechanism. The colours observed in the test are due to halochromism.

Tristhiolato Pseudopeptides Bind Arsenic(III) in an AsS3 Coordination Environment Imitating Metalloid Binding Sites in Proteins.

The AsIII binding of two NTA-based tripodal pseudopeptides, possessing three cysteine (ligand L1) or d-penicillamine residues (ligand L2) as potential coordinating groups for soft semimetals or metal ions, was studied by experimental (UV, CD, NMR, and ESI-MS) and theoretical (DFT) methods. All of the experimental data, obtained with the variation of the AsIII:ligand concentration ratios or pH values in some instances, evidence the exclusive formation of species with an AsS3-type coordination mode. The UV-monitored titration of the ligands with arsenous acid at pH = 7.0 provided an absorbance data set that allowed for the determination of apparent stability constants of the forming species. The obtained stabilities (logK' = 5.26 (AsL1) and logK' = 3.04 (AsL2)) reflect high affinities, especially for the sterically less restricted cysteine derivative. DFT calculated structures correlate well with the spectroscopic results and, in line with the 1H NMR data, indicate a preference for the all-endo conformers resembling the AsIII environment at the semimetal binding sites in various metalloproteins.

Prenatal arsenic exposure, arsenic metabolism and neurocognitive development of 2-year-old children in low-arsenic areas

BackgroundThere is limited evidence on the effects of arsenic species and metabolic capacity on child neurodevelopment, particularly at low levels. Further, little is known about the critical window of exposure. ObjectiveTo estimate the associations of arsenic exposure and arsenic metabolism in different pregnancy periods with neurodevelopment of two-year-old children. MethodsConcentrations of arsenobetaine (AsB), arsenite, arsenate, monomethyl arsenic acid (MMA), and dimethyl arsenic acid (DMA) in urine samples collected in three trimesters from 1006 mothers were measured using HPLC − ICPMS. Inorganic arsenic (iAs) was calculated as the sum of arsenite and arsenate. Total arsenic (tAs) was calculated as the sum of iAs, MMA and DMA. Child neurodevelopment was assessed with the Bayley Scales of Infant Development. ResultsThe geometric mean (GM) of SG-adjusted tAs in the first, second, third trimester was 16.37, 12.94, 13.04 μg/L, respectively. The mental development index (MDI) score was inversely associated with iAs and tAs. Compared to the 1st quartile, the MDI score decreased 0.43 (95%CI: −4.22, 3.36) for the 2nd, 6.50 (95%CI: −11.73, −1.27) for the 3rd, 5.42 (95%CI: −10.74, −0.10) for the 4th quartiles of iAs, and decreased 4.03 (95%CI: −7.90, −0.15) in the 4th quartile of tAs. In trimester-specific models, negative associations of DMA [−1.94 (95%CI: −3.18, −0.71)] and tAs [−1.61 (95%CI: −3.02, −0.20)] with the psychomotor development index (PDI) were only observed in 1st trimester. ConclusionsOur study found inverse associations between prenatal arsenic exposure, especially in early pregnancy, and neurodevelopment of children at two years old, even at low exposure levels.

Application of infrared spectroscopy and its theoretical simulation to arsenic adsorption processes.

Accurate detection and analysis of arsenic pollutants are an important means to enhance the ability to manage arsenic pollution. Infrared (IR) spectroscopy technology has the advantages of fast analysis speed, high resolution, and high sensitivity and can be monitored by real-time in situ analysis. This paper reviews the application of IR spectroscopy in the qualitative and quantitative analysis of inorganic and organic arsenic acid adsorbed by major minerals such as ferrihydrite (FH), hematite, goethite, and titanium dioxide. The IR spectroscopy technique cannot only identify different arsenic contaminants but also obtain the content and adsorption rate of arsenic contaminants in the solid phase. The reaction equilibrium constants and the degree of reaction conversion can be determined by constructing adsorption isotherms or combining them with modeling techniques. Theoretical calculations of IR spectra of mineral adsorbed arsenic pollutant systems based on density functional theory (DFT) and analysis and comparison of the measured and theoretically calculated characteristic peaks of IR spectra can reveal the microscopic mechanism and surface chemical morphology of the arsenic adsorption process. This paper systematically summarizes the qualitative and quantitative studies and theoretical calculations of IR spectroscopy in inorganic and organic arsenic pollutant adsorption systems, which provides new insights for accurate detection and analysis of arsenic pollutants and arsenic pollution control. PRACTITIONER POINTS: This paper reviews the application of infrared spectroscopy in the qualitative and quantitative analyses of inorganic and organic arsenic acid adsorbed by major minerals such as ferrihydrite, hematite, goethite, and titanium dioxide, which can help identify and evaluate the type and concentration of arsenic pollutants in water bodies. In this paper, theoretical calculations of infrared spectra of mineral adsorbed arsenic pollutant systems based on density functional theory reveal the adsorption mechanism of arsenic pollutants in water at the solid-liquid interface and help to develop targeted arsenic pollution control technologies. This paper provides a new and reliable analytical detection technique for the study of arsenic contaminants in water bodies.

Fate of 14 C-MSMA in a soil column study simulating herbicide use environments.

Monosodium methanearsonate (MSMA), a selective contact herbicide, is a sodium salt of monomethyl arsenic acid (MMA or MAA). This paper focuses on the environmental fate of MMA. Decades of research have shown that a significant portion of applied MSMA drips to soil and is sorbed quickly. The fraction available for leaching or biological uptake decreases at a biphasic rate, first rapidly and then at a slower rate. A soil column study was designed to obtain quantitative information about MMA sorption and transformation and the effects of different environmental variables on these processes, in conditions simulating the environment of MSMA use on cotton and turf. Using 14 C-MSMA, this study quantified MSMA-derived arsenic species and differentiated between added arsenic and soil background levels. Similar behavior of MSMA was observed across all test systems with respect to sorption, transformation, and mobility, despite differences in soil type and rainfall treatment. All soil columns exhibited a rapid sorption of added MMA followed by continual sorption of residues into the soil matrix. Within the first 2 days, only 20%-25% of radioactivity was extracted by water. On day 90, less than 3.1% of added MMA was in a water extractable phase. MMA sorption was most rapid in the soil with the higher clay content. Dominant extractable arsenic species were MMA, dimethylarsinic acid, and arsenate, indicating that methylation and demethylation occurred. In all MSMA-treated columns, arsenite concentrations were negligible and indiscernible from those in untreated columns.

Speciated and Total Urinary Arsenic Levels in Belo Horizonte, the Largest Brazilian City within the Mineral-Rich Region “Iron Quadrangle”

The “Quadrilátero Ferrífero” (Iron Quadrangle) is a mineral-rich province in Brazil, where arsenic anomalies are associated with gold mining and tailings dam failures. Urine samples were randomly collected from residents of Belo Horizonte (BH) city (N = 506 total/138 speciation) and the metropolitan area (N = 35 total/10 speciation), with stratifications in age, female-male and geopolitical regions. Creatinine, acid-digested total arsenic (TAs), and five inorganic and organic arsenic species were measured: arsenobetaine (AsB); arsenous (AsIII) and arsenic (AsV) acids and their dissociation products; monomethylarsonic acid (MMA); and dimethylarsinic acid DMA). Overall, the TAs GM (μg/g creat) of all stratification groups indicated no statistical difference. The TAs geometric mean (GM) of BH was 9.68 [9.17–10.2] μg/g creat, being AsB (43.8%) and DMA (20.7%) the major components. The toxic arsenic (ToxAs) fraction (i.e., AsIII + AsV + MMA + DMA) was 5.23 [4.45–6.15] μg/L. These TAs and ToxAs values are lower than international benchmarks and the Brazilian legislated standard of 35 μg/L for ToxAs. The TAs GM (μg/L) and creatinine were 36% higher for males than for females (p < 0.0001), making TAs GMs comparable, after creatinine correction. Similarly, though the 10–19 age group showed significantly higher ToxAs GM (12.7 [6.49–24.8] μg/L) (p = 0.048) and creatinine (p < 0.001), the ToxAs GM (7.22 [2.92–17.9] μg/g creat), was not statistically different than those from the other age groups. The study, the first one in Brazil, identifies the relative contribution of inorganic and organic arsenic and provides a baseline level for clinical reference and bio-monitoring studies, particularly applicable to both occupational and non-occupational populations in a mineral-rich region.Graphical abstract

Risk of Environmental Chemicals on Bone Fractures Is Independent of Low Bone Mass in US Adults: Insights from 2017 to 2018 NHANES

To assess the association of environmental chemical factors with osteopenia and/or bone fractures. All data were extracted from the National Health and Nutrition Survey (NHANES) 2017-2018 of American adults aged 20-59 years old; invalid data were excluded based on dual-energy X-ray absorptiometry. For the ultimate valid data set, multivariate logistic regression models were applied to evaluate the association of environmental chemical factors with osteopenia and bone fractures. The valid dataset was obtained from 2640 individuals, who completed a questionnaire of demographic characteristics. Urinary manganese and monomethylarsonic acid were positively associated with osteopenia in American adults, but not bone fracture. However, several environmental factors (e.g., arsenous acid, arsenocholine, dimethylarsinic acid, and 2-thioxothiazolidine-4-carboxylic acid) did not affect bone mineral density, but were significantly associated with bone fracture. Multiple environmental chemical factors significantly affect bone mass or fracture risk. However, the risk of environmental chemical factors on fractures is independent of osteopenia in US Adults. The influence of environmental chemical factors on bone quality should be considered and monitored.

Associations of arsenic exposure with liver injury in US adults: NHANES 2003-2018.

Arsenic is a natural element with complex toxicity. Long-term exposure to arsenic can cause a variety of health damage. In recent years, there are some studies on arsenic exposure and liver injury. But few of them tried to measure the quantitative relationship between arsenic exposure and indicators of liver injury in adult. Therefore, this study aimed to elucidate the relationship between them. This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES) in 2003-2018. Arsenic exposure was assessed using total urinary arsenic and dimethylarsenate acid (DMA). We selected alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), total protein (TP), ALT/AST, total bilirubin (TBIL), and albumin (ALB) as markers of liver injury. Multiple linear regression was used to explore the relationship between urinary arsenic concentrations and these markers of liver function injury. In addition, six covariables (age, sex, smoker, alcohol user, BMI, diabetes) were further analyzed in subgroups. A total of 13,420 adults were included in the analysis. The multivariate linear regression analyses showed that urinary DMA was positively correlated with ALT (β 0.135, 95%CI 0.090, 0.180, p < 0.001), AST (β 0.053, 95%CI 0.014, 0.092, p < 0.01), ALT/AST (β 0.052, 95%CI 0.030, 0.074, p < 0.001), TBIL (β 0.061, 95%CI 0.034, 0.089, p < 0.001), and GGT (β 0.178, 95%CI 0.110, 0.246, p < 0.001). Similar results were observed for total urinary arsenic, suggesting a positive association with AST (β 0.048, 95%CI 0.016, 0.081, p < 0.01), ALT (β 0.090, 95%CI 0.049, 0.132, p < 0.001), and TBIL (β 0.062, 95%CI 0.037, 0.088, p < 0.001). In subgroup analysis, sex and smoker showed significant differences between subgroups. Our results demonstrate a positive association between urinary arsenic exposure and liver injury in adults. Sex and smokers may be related to arsenic pathogenicity.

Difference of solidophilic atoms in collectors: Enlightenments for flotation separation of spodumene and feldspar

In this paper, the effect of benzyl arsenic acid (BAA) and sodium oleate (NaOl) on mineral flotation was studied for the first time from the perspective of the difference of solidophilic atom. Compared with NaOl, the solidophilic O atoms of BAA had stronger electronegativity and the bonding strength of As-O was lower than that of CO. Thus, when BAA adsorbed on the mineral surfaces, the bonding strength of the solidophilic O atoms with the adsorption sites would be higher. The DFT calculation of adsorption model indicated that after activation by Ca(OH)+, the adsorption capacity of BAA on spodumene surface was significantly higher than that of NaOl, while the adsorption strength on feldspar was similar to that of NaOl. This result was corroborated by flotation experiment and adsorption capacity test. Thus, compared with NaOl, BAA could separate and recover spodumene more effectively.