Residential exposure to drinking water arsenic in Inner Mongolia, China

Detection of Phenylarsine Oxide in Drinking Water Using an Impedimetric Electrochemical Sensor with Gelatin-Based Solid Electrolyte Enriched with Mercaptoethanol: A Novel Prospective Green Biosensor Methodology

A simple, inexpensive, rapid, and label-free detection of phenylarsine oxide (PAO) in the field is a significant and unmet need because of its fatally acute and chronic effects on human health. A simple, fast, sensitive, and relatively low-cost arsenic detection system with an eco-friendly sensor could fill this gap. To monitor arsenic in situ, a reliable, portable impedimetric electrochemical sensor is the most suitable platform, which is real-time, fast, low-cost, and easy to design and use and has high sensitivity at low detection limits in the nanogram per mL range. The detection system in this study has a patent-applied green sensor with minimum harm to nature and the potential to dissolve in nature. The electrode containing 15 mL of distilled water (DIW) + 2 g gelatin + 1.75 g glycerol was determined to be the most suitable for determining the amount of inorganic arsenic in the range of 1-100 ng/mL using a gelatin-based solid electrochemical sensor enriched with 2-mercaptoethanol. Impedance measurements were performed to analyze the stability of the sensor in both deionized water and drinking water, as well as for arsenic detection. Among the procedures examined, the procedure prepared with 15 mL DIW + 2 g glycerol + 1.75 g gelatin resulted in the best stability in aqueous medium and in sensitivity with resistance changes (-ΔR _ct (%)) of 12% (±0.62%), 26% (±2.3%), and 40% (±3.8%) for the concentrations of 1, 10, and 100 ng/mL PAO in drinking water, respectively. With this detection methodology, there is the potential to detect not only arsenic but also other heavy metals in waters and different biomarkers in human fluids.

Life-long arsenic exposure damages the microstructure of the rat hippocampus

Epidemiological studies demonstrate that arsenic exposure is associated with cognitive dysfunction. Experimental arsenic exposure models showed learning and memory deficits and molecular changes resembling the functional and pathologic neurodegeneration features. The present work focuses on hippocampal pathological changes in Wistar rats induced by continuous arsenic exposure from in utero up to 12 months of age, evaluated by magnetic resonance imaging along with immunohistochemistry. Diffusion-weighted images revealed age-related lower fractional anisotropy and higher radial-axial and mean diffusivity at 6 and 12 months, indicating that arsenic exposure leads to hippocampal demyelination. These structural alterations were paralleled by immunohistochemical changes that showed a significant loss of myelin basic protein in CA1 and CA3 regions accompanied by increased glial fibrillary acidic protein expression at all time-points studied. Concomitantly, arsenic exposure induced an altered morphology of astrocytes at all studied ages, whereas increased synaptogenesis was only observed at two months of age. These results suggest that environmental arsenic exposure is linked to impaired hippocampal connectivity and perhaps early glial senescence, which together might resemble a premature aging phenomenon leading to cognitive deficits.

Linker-Free Magnetite-Decorated Gold Nanoparticles (Fe3O4-Au): Synthesis, Characterization, and Application for Electrochemical Detection of Arsenic (III)

Linker-free magnetite nanoparticles (Fe3O4NPs)-decorated gold nanoparticles (AuNPs) were grown using a new protocol that can be used as a new platform for synthesis of other intact metal-metal oxide nanocomposites without the need for linkers. This minimizes the distance between the metal and metal oxide nanoparticles and ensures the optimum combined effects between the two material interfaces. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy confirmed the successful synthesis of the Fe3O4-Au nanocomposite, without any change in the magnetite phase. Characterization, using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy, revealed the composite to consist of AuNPs of 70 ± 10 nm diameter decorated with tiny 10 ± 3 nm diameter Fe3O4NPs in Au:Fe mass ratio of 5:1. The prepared Fe3O4-Au nanocomposite was embedded in ionic liquid (IL) and applied for the modification of glassy carbon electrode (GCE) for the electrochemical detection of As(III) in water. By combining the excellent catalytic properties of the AuNPs with the high adsorption capacity of the tiny Fe3O4NPs towards As(III), as well as the good conductivity of IL, the Fe3O4-Au-IL nanocomposite showed excellent performance in the square wave anodic stripping voltammetry detection of As(III). Under the optimized conditions, a linear range of 1 to 100 μg/L was achieved with a detection limit of 0.22 μg/L (S/N = 3), and no interference from 100-fold higher concentrations of a wide variety of cations and anions found in water. A very low residual standard deviation of 1.16% confirmed the high precision/reproducibility of As(III) analysis and the reliability of the Fe3O4-Au-IL sensing interface. Finally, this proposed sensing interface was successfully applied to analyzing synthetic river and wastewater samples with a 95-101% recovery, demonstrating excellent accuracy, even in complex synthetic river and wastewater samples containing high concentrations of humic acid without any sample pretreatments.

Electrochemical Deposition of Gold Nanoparticles on Reduced Graphene Oxide by Fast Scan Cyclic Voltammetry for the Sensitive Determination of As(III)

In this study, a stable, sensitive electrochemical sensor was fabricated by the electrochemical codeposition of reduced graphene oxide (rGO) and gold nanoparticles on a glassy carbon electrode (rGO-Au_nano/GCE) using cyclic voltammetry (CV), which enabled a simple and controllable electrode modification strategy for the determination of trace As(III) by square wave anodic stripping voltammetry (SWASV). SWASV, CV, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the electrochemical properties and morphology of the proposed sensing platform. The number of sweep segments, the deposition potential and the deposition time were optimized to obtain ideal sensitivity. The presence of rGO from the electroreduction of graphene oxide on the sensing interface effectively enlarged the specific surface area and consequently improved the preconcentration capacity for As(III). The rGO-Au_nano/GCE sensor exhibited outstanding detection performance for As(III) due to the combined effect of Au_nano and rGO formed during the electroreduction process. Under the optimized conditions, a linear range from 13.375 × 10⁻⁹ to 668.75 × 10⁻⁹ mol/L (1.0 to 50.0 μg/L) was obtained with a detection limit of 1.07 × 10⁻⁹ mol/L (0.08 μg/L) (S/N = 3). The reproducibility and reliability of the rGO-Au_nano/GCE sensor were also verified by performing 8 repetitive measurements. Finally, the rGO-Au_nano/GCE sensor was used for the analysis of real samples with satisfactory results.

CeO2 Nanowire-BODIPY-Adenosine Triphosphate Fluorescent Sensing Platform for Highly Specific and Sensitive Detection of Arsenate

Effective and sensitive monitoring of arsenate in drinking water is significant for risk management of public health. Here, we demonstrated that a CeO₂ nanowire acted as an efficient quencher for small fluorescent molecules with a phosphate group, BODIPY-adenosine triphosphate (BODIPY-ATP) and riboflavin-5'-phosphate (Rf-P), and developed a CeO₂ nanowire-BODIPY-ATP platform for highly selective and sensitive detection of arsenate. The response strategy was based on the competitive coordination chemistry of CeO₂ nanowire between arsenate and phosphate group of BODIPY-ATP. Arsenate displaced adsorbed BODIPY-ATP to enhance fluorescence, allowing detection of arsenate down to 7.8 nM, which is lower than the WHO-defined limit of 130 nM. An excellent linear range of 20-150 and 150-1000 nM was obtained. Importantly, this system was simple in design and convenient in operation. Also, the platform exhibited excellent selectivity for arsenate without the interference of phosphate ions. Finally, the proposed method had been successfully employed for determination of arsenate in real water samples.

Arsenic Induces Members of the mmu-miR-466-669 Cluster Which Reduces NeuroD1 Expression

Chronic arsenic exposure can result in adverse development effects including decreased intellectual function, reduced birth weight, and altered locomotor activity. Previous in vitro studies have shown that arsenic inhibits stem cell differentiation. MicroRNAs (miRNAs) are small noncoding RNAs that regulate multiple cellular processes including embryonic development and cell differentiation. The purpose of this study was to examine whether altered miRNA expression was a mechanism by which arsenic inhibited cellular differentiation. The pluripotent P19 mouse embryonal carcinoma cells were exposed to 0 or 0.5 μM sodium arsenite for 9 days during cell differentiation, and changes in miRNA expression was analyzed using microarrays. We found that the expression of several miRNAs important in cellular differentiation, such as miR-9 and miR-199 were decreased by 1.9- and 1.6-fold, respectively, following arsenic exposure, while miR-92a, miR-291a, and miR-709 were increased by 3-, 3.7-, and 1.6-fold, respectively. The members of the miR-466-669 cluster and its host gene, Scm-like with 4 Mbt domains 2 (Sfmbt2), were significantly induced by arsenic from 1.5- to 4-fold in a time-dependent manner. Multiple miRNA target prediction programs revealed that several neurogenic transcription factors appear to be targets of the cluster. When consensus anti-miRNAs targeting the miR-466-669 cluster were transfected into P19 cells, arsenic-exposed cells were able to more effectively differentiate. The consensus anti-miRNAs appeared to rescue the inhibitory effects of arsenic on cell differentiation due to an increased expression of NeuroD1. Taken together, we conclude that arsenic induces the miR-466-669 cluster, and that this induction acts to inhibit cellular differentiation in part due to a repression of NeuroD1.

The problem of identifying arsenic anomalies in the basin of Sahand dam through risk-based 'soft modelling'

An investigation is undertaken to identify arsenic anomalies at the complex of Sahand dam, East Azerbaijan, northwest Iran. The complex acts as a system, in which the impounding reservoir catalyses system components related to Origin-Source-Pathways-Receptor-Consequence (OSPRC) viewed as a risk system. This 'conceptual framework' overlays a 'perceptual model' of the physical system, in which arsenic with geogenic origins diffused into the formations through extensive fractures swept through the region during the Miocene era. Impacts of arsenic anomalies were local until the provision of the impounding reservoir in the last 10years, which transformed it into active system-wide risk exposures. The paper uses existing technique of: statistical, graphical, multivariate analysis, geological survey and isotopic study, but these often seem ad hoc and without common knowledgebase. Risk analysis approaches are sought to treat existing fragmentation in practices of identifying and mitigating arsenic anomalies. The paper contributes towards next generation best practice through: (i) transferring and extending knowledge on the OSPRC framework; (ii) introducing 'OSPRC cells' to capture unique idiosyncrasies at each cell; and (iii) suggesting a 'soft modelling' procedure based on assembling knowledgebase of existing techniques with partially converging and partially diverging information levels, where knowledgebase invokes model equations with increasing resolutions. The data samples from the study area for the period of 2002-12 supports the study and indicates the following 'risk cells' for the study area: (i) local arsenic risk exposures at south of the reservoir, (ii) system-wide arsenic risks at its north; and (iii) system-wide arsenic risk exposures within the reservoir even after dilution.

Robust electrochemical analysis of As(III) integrating with interference tests: a case study in groundwater

In Togtoh region of Inner Mongolia, northern China, groundwater encountered high concentrations As contamination (greater than 50 μg L(-1)) causes an increasing concern. This work demonstrates an electrochemical protocol for robust (efficient and accurate) determination of As(III) in Togtoh water samples using Au microwire electrode without the need of pretreatment or clean-up steps. Considering the complicated conditions of Togtoh water, the efficiency of Au microwire electrode was systematically evaluated by a series of interference tests, stability and reproducibility measurements. No obvious interference on the determination of As(III) was observed. Especially, the influence of humic acid (HA) was intensively investigated. Electrode stability was also observed with long-term measurements (70 days) in Togtoh water solution and under different temperatures (0-35 °C). Excellent reproducibility (RSD:1.28%) was observed from different batches of Au microwire electrodes. The results obtained at Au microwire electrode were comparable to that obtained by inductively coupled plasma atomic emission spectroscopy (ICP-AES), indicating a good accuracy. These evaluations (efficiency, robustness, and accuracy) demonstrated that the Au microwire electrode was able to determine As(III) in application to real environmental samples.

Role of Fe(III) in preventing humic interference during As(III) detection on gold electrode: spectroscopic and voltammetric evidence

A drawback of As(III) detection using square wave anodic stripping voltammetry (SWASV) is that it is susceptible to interferences from various metals or organic compounds, especially in real sample water. This study attempts to understand the interference of co-existing of Fe(III) and humic acid (HA) molecules to the electrochemical detection of As(III) using Fourier transform infrared (FTIR) spectrum and X-ray photoelectron spectroscopy (XPS). The electrochemical experiments include stripping of As(III) in the solutions containing HA with different concentrations, cyclic voltammetry in 0.5M H2SO4 in the presence of HA or Fe(III) with/without addition of Fe(III) or HA, and stripping of As(III) in the presence of HA or Fe(III) with/without addition of Fe(III) or HA. FTIR and XPS are employed to confirm the affinity of HA to Fe(III) or As(III) in acidic condition.

Effect of therapeutic arsenic exposure on pulmonary function

AIM

Arsenic-contaminated drinking water has been associated with respiratory diseases and lung function impairment. Oral arsenic trioxide (ATO) is a standard treatment for acute promyelocytic leukaemia. This study aimed to explore the effect of therapeutic exposure to arsenic on lung function.

PATIENTS AND METHOD

This was a case-control cross-sectional study on patients with haematological malignancies with or without exposure to ATO. Full lung function tests and serum Clara cell protein 16 (CC16) were measured.

RESULTS

There were 57 cases (arsenic exposed) and 57 matched controls (arsenic non-exposed) recruited. Among cases, the median duration of ATO exposure was 519 (194-1259) days. The mean FEV(1)/FVC ratio, FEV(1) (% predicted), and RV/TLC (%), as well as % subjects with FEV(1)/FVC below lower limits of normal (LLN), were similar in the two groups with or without arsenic exposure. However the mean TLC (% predicted) and DLCO/VA were significantly higher in arsenic-exposed versus non-exposed group (p = 0.01 and p = 0.008 respectively). There were mildly reduced FEV(1)/FVC ratio and FEF(25-75) (% predicted), largely within normal limits, among high level arsenic exposure compared with non-exposure (p = 0.01 and p = 0.05 respectively). Serum CC16 was comparable among both arsenic exposed and non-exposed groups.

CONCLUSION

Therapeutic use of oral ATO for a median of around 1.5 years was not associated with clinically significant lung function impairment.

Environmental contaminant exposures and preterm birth: a comprehensive review

Preterm birth is a significant public health concern, as it is associated with high risk of infant mortality, various morbidities in both the neonatal period and later in life, and a significant societal economic burden. As many cases are of unknown etiology, identification of the contribution of environmental contaminant exposures is a priority in the study of preterm birth. This is a comprehensive review of all known studies published from 1992 through August 2012 linking maternal exposure to environmental chemicals during pregnancy with preterm birth. Using PubMed searches, studies were identified that examined associations between preterm birth and exposure to five categories of environmental toxicants, including persistent organic pollutants, drinking-water contaminants, atmospheric pollutants, metals and metalloids, and other environmental contaminants. Individual studies were summarized and specific suggestions were made for future work in regard to exposure and outcome assessment methods as well as study design, with the recommendation of focusing on potential mediating toxicological mechanisms. In conclusion, no consistent evidence was found for positive associations between individual chemical exposures and preterm birth. By identifying limitations and addressing the gaps that may have impeded the ability to identify true associations thus far, this review can guide future epidemiologic studies of environmental exposures and preterm birth.

Natural contamination with arsenic and other trace elements in groundwater of the Central-West region of Chaco, Argentina

This study covered the central agricultural region of the Chaco province, which lacks a permanent river networks. However, during the rainy period there is localized groundwater recharge. About 84 groundwater samples were taken during the period April-December 2007. These groundwater samples were collected from two different depths: 62 samples from shallow wells (4 to 20 m) and 24 samples from deep wells (20 to 100 m). Chemical variables were determined: pH, specific conductance, total dissolved solid, hardness, alkalinity, HCO(3)-, CO(3)(2-), SO(4)(2-), Cl-, NO(3)-, NO(2) -, NH(4)+, F-, As((tot)), Na+, K+, Ca2+, Mg2+, Fe, Cu, Ni, Pb and Zn. The chemical composition of groundwater in the study area is dominantly sodium bicarbonate and sodium chloride bicarbonate, comprising more than 60% (52/86) of shallow and deep groundwater samples. Of the 86 analyzed groundwater samples, 88% exceeded the WHO (World Health Organization) and CAA (Código Alimentario Argentino) standards (10 μg/L) for As (arsenic) and 9% exceeded the WHO standard (1.5 mg/L) for F(-).Groundwater highly contaminated with As (max. 1,073 μg/L) and F- (max. 4.2 mg/L) was found in shallow aquifer. The contaminated groundwater is characterized by high pH (max. 8.9), alkalinity (max. HCO(3)- 1,932 mg/L), SO(4)(2-) (max. 11,862 mg/L), Na(+) (max. 3,158 mg/L), Cl(-) (max. 10,493 mg/L) and electric conductivity greater than 33.3 μS/cm. Other associated elements (Ni, Pb, Cu and Zn) are present in low concentrations, except for Fe that in 32% of samples exceeded the guideline value of 0.3 mg/L suggested by the CAA.

Arsenic contamination of natural waters in San Juan and La Pampa, Argentina

Arsenic (As) speciation in surface and groundwater from two provinces in Argentina (San Juan and La Pampa) was investigated using solid phase extraction (SPE) cartridge methodology with comparison to total arsenic concentrations. A third province, Río Negro, was used as a control to the study. Strong cation exchange (SCX) and strong anion exchange (SAX) cartridges were utilised in series for the separation and preservation of arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MA(V)) and dimethylarsinic acid (DMA(V)). Samples were collected from a range of water outlets (rivers/streams, wells, untreated domestic taps, well water treatment works) to assess the relationship between total arsenic and arsenic species, water type and water parameters (pH, conductivity and total dissolved solids, TDS). Analysis of the waters for arsenic (total and species) was performed by inductively coupled plasma mass spectrometry (ICP-MS) in collision cell mode. Total arsenic concentrations in the surface and groundwater from Encon and the San José de Jáchal region of San Juan (north-west Argentina within the Cuyo region) ranged from 9 to 357 μg l(-1) As. Groundwater from Eduardo Castex (EC) and Ingeniero Luiggi (LU) in La Pampa (central Argentina within the Chaco-Pampean Plain) ranged from 3 to 1326 μg l(-1) As. The pH range for the provinces of San Juan (7.2-9.7) and La Pampa (7.0-9.9) are in agreement with other published literature. The highest total arsenic concentrations were found in La Pampa well waters (both rural farms and pre-treated urban sources), particularly where there was high pH (typically > 8.2), conductivity (>2,600 μS cm(-1)) and TDS (>1,400 mg l(-1)). Reverse osmosis (RO) treatment of well waters in La Pampa for domestic drinking water in EC and LU significantly reduced total arsenic concentrations from a range of 216-224 μg l(-1) As to 0.3-0.8 μg l(-1) As. Arsenic species for both provinces were predominantly As(III) and As(V). As(III) and As(V) concentrations in San Juan ranged from 4-138 μg l(-1) to <0.02-22 μg l(-1) for surface waters (in the San José de Jáchal region) and 23-346 μg l(-1) and 0.04-76 μg l(-1) for groundwater, respectively. This translates to a relative As(III) abundance of 69-100% of the total arsenic in surface waters and 32-100% in groundwater. This is unexpected because it is typically thought that in oxidising conditions (surface waters), the dominant arsenic species is As(V). However, data from the SPE methodology suggests that As(III) is the prevalent species in San Juan, indicating a greater influence from reductive processes. La Pampa groundwater had As(III) and As(V) concentrations of 5-1,332 μg l(-1) and 0.09-592 μg l(-1) for EC and 32-242 μg l(-1) and 30-277 μg l(-1) As for LU, respectively. Detectable levels of MA(V) were reported in both provinces up to a concentration of 79 μg l(-1) (equating to up to 33% of the total arsenic). Previously published literature has focused primarily on the inorganic arsenic species, however this study highlights the potentially significant concentrations of organoarsenicals present in natural waters. The potential for separating and preserving individual arsenic species in the field to avoid transformation during transport to the laboratory, enabling an accurate assessment of in situ arsenic speciation in water supplies is discussed.

Well water arsenic exposure, arsenic induced skin-lesions and self-reported morbidity in Inner Mongolia

Residents of the Bayingnormen region of Inner Mongolia have been exposed to arsenic-contaminated well water for over 20 years, but relatively few studies have investigated health effects in this region. We surveyed one village to document exposure to arsenic and assess the prevalence of arsenic-associated skin lesions and self-reported morbidity. Five-percent (632) of the 12,334 residents surveyed had skin lesions characteristics of arsenic exposure. Skin lesions were strongly associated with well water arsenic and there was an elevated prevalence among residents with water arsenic exposures as low as 5 μg/L-10 μg/L. The presence of skin lesions was also associated with self-reported cardiovascular disease.

Increased mortality associated with well-water arsenic exposure in Inner Mongolia, China

We conducted a retrospective mortality study in an Inner Mongolian village exposed to well water contaminated by arsenic since the 1980s. Deaths occurring between January 1, 1997 and December 1, 2004 were classified according to underlying cause and water samples from household wells were tested for total arsenic. Heart disease mortality was associated with arsenic exposure, and the association strengthened with time exposed to the water source. Cancer mortality and all-cause mortality were associated with well-water arsenic exposure among those exposed 10-20 years. This is the first study to document increased arsenic-associated mortality in the Bayingnormen region of Inner Mongolia.

Drinking water arsenic exposure and blood pressure in healthy women of reproductive age in Inner Mongolia, China

The extremely high exposure levels evaluated in prior investigations relating elevated levels of drinking water arsenic and hypertension prevalence make extrapolation to potential vascular effects at lower exposure levels very difficult. A cross-sectional study was conducted on 8790 women who had recently been pregnant in an area of Inner Mongolia, China known to have a gradient of drinking water arsenic exposure. This study observed increased systolic blood pressure levels with increasing drinking water arsenic, at lower exposure levels than previously reported in the literature. As compared to the referent category (below limit of detection to 20 microg of As/L), the overall population mean systolic blood pressure rose 1.29 mm Hg (95% CI 0.82, 1.75), 1.28 mm Hg (95% CI 0.49, 2.07), and 2.22 mm Hg (95% CI 1.46, 2.97) as drinking water arsenic concentration increased from 21 to 50, 51 to 100, and >100 microg of As/L, respectively. Controlling for age and body weight (n=3260), the population mean systolic blood pressure rose 1.88 mm Hg (95% CI 1.03, 2.73), 3.90 mm Hg (95% CI 2.52, 5.29), and 6.83 mm Hg (95% CI 5.39, 8.27) as drinking water arsenic concentration increased, respectively. For diastolic blood pressure effect, while statistically significant, was not as pronounced as systolic blood pressure. Mean diastolic blood pressure rose 0.78 mm Hg (95% CI 0.39, 1.16), 1.57 mm Hg (95% CI 0.91, 2.22) and 1.32 mm Hg (95% CI 0.70, 1.95), respectively, for the overall population and rose 2.11 mm Hg (95% CI 1.38, 2.84), 2.74 mm Hg (95% CI 1.55, 3.93), and 3.08 mm Hg (95% CI 1.84, 4.31), respectively, for the adjusted population (n=3260) at drinking water arsenic concentrations of 21 to 50, 51 to 100, and >100 microg of As/L. If our study results are confirmed in other populations, the potential burden of cardiovascular disease attributable to drinking water arsenic is significant.