Groundwater arsenic contamination in Bangladesh and West Bengal, India

Arsenic Exposure-Related Hypertension in Bangladesh and Reduced Circulating Nitric Oxide Bioavailability

BACKGROUND

Hypertension is a major cause of death worldwide. Although arsenic exposure has been associated with the risk of hypertension, this association appears nonuniform due to inconsistent results from studies conducted in different populations. Moreover, hypertension is a complex condition with multiple underlying mechanisms and factors. One factor is impaired production and bioavailability of vascular nitric oxide (NO). However, the implications of the effects of arsenic exposure on circulating NO and its association with hypertension in humans are largely unknown.

OBJECTIVE

We investigated the dose-response relationship between arsenic exposure and hypertension with vascular NO levels as a potential mediator of arsenic-related hypertension in individuals exposed to a broad range of arsenic.

METHODS

A total of 828 participants were recruited from low- and high-arsenic exposure areas in Bangladesh. Participants' drinking water, hair, and nail arsenic concentrations were measured by inductively coupled plasma mass spectroscopy. Hypertension was defined as a systolic blood pressure (SBP) value of ≥ 140 and a diastolic (DBP) value of ≥ 90  mmHg . Serum NO levels reflected by total serum nitrite concentrations were measured by immunoassay. A formal causal mediation analysis was used to assess NO as a mediator of the association between arsenic level and hypertension.

RESULTS

Increasing concentrations of arsenic measured in drinking water, hair, and nails were associated with the increasing levels of SBP and DBP. The odds of hypertension were dose-dependently increased by arsenic even in participants exposed to relatively low to moderate levels (10 - 50 μ g / L ) of water arsenic [odds ratios (ORs) and 95% confidence intervals (CIs): 2.87 (95% CI: 1.28, 6.44), 2.67 (95% CI: 1.27, 5.60), and 5.04 (95% CI: 2.71, 9.35) for the 10 - 50 μ g / L , 50.01 - 150 μ g / L , and > 150 μ g / L groups, respectively]. Causal mediation analysis showed a significant mediating effect of NO on arsenic-related SBP, DBP, and hypertension.

CONCLUSION

Increasing exposure to arsenic was associated with increasing odds of hypertension. The association was mediated through the reduction of vascular NO bioavailability, suggesting that impaired NO bioavailability was a plausible underlying mechanism of arsenic-induced hypertension in this Bangladeshi population. https://doi.org/10.1289/EHP13018.

A comprehensive review of human health risks of arsenic and fluoride contamination of groundwater in the South Asia region

The present study found that ∼80 million people in India, ∼60 million people in Pakistan, ∼70 million people in Bangladesh, and ∼3 million people in Nepal are exposed to arsenic groundwater contamination above 10 μg/L, while Sri Lanka remains moderately affected. In the case of fluoride contamination, ∼120 million in India, >2 million in Pakistan, and ∼0.5 million in Sri Lanka are exposed to the risk of fluoride above 1.5 mg/L, while Bangladesh and Nepal are mildly affected. The hazard quotient (HQ) for arsenic varied from 0 to 822 in India, 0 to 33 in Pakistan, 0 to 1,051 in Bangladesh, 0 to 582 in Nepal, and 0 to 89 in Sri Lanka. The cancer risk of arsenic varied from 0 to 1.64 × 1-1 in India, 0 to 1.07 × 10-1 in Pakistan, 0 to 2.10 × 10-1 in Bangladesh, 0 to 1.16 × 10-1 in Nepal, and 0 to 1.78 × 10-2 in Sri Lanka. In the case of fluoride, the HQ ranged from 0 to 21 in India, 0 to 33 in Pakistan, 0 to 18 in Bangladesh, 0 to 10 in Nepal, and 0 to 10 in Sri Lanka. Arsenic and fluoride have adverse effects on animals, resulting in chemical poisoning and skeletal fluorosis. Adsorption and membrane filtration have demonstrated outstanding treatment outcomes.

Methylation of arsenic in rice: Mechanisms, factors, and mitigation strategies

Arsenic contamination in rice poses a significant health risk to rice consumers across the globe. This review examines the impact of water source and type on the speciation and methylation of arsenic in rice. The review highlights that groundwater used for irrigation in arsenic-affected regions can lead to higher total arsenic content in rice grains and lower proportions of methylated arsenic species. The methylation of As in rice is influenced by microbial activity in groundwater, which can methylate arsenic that is taken up by rice plants. Reclaimed water irrigation can also increase the risk of arsenic accumulation in rice crops, although the use of organic amendments and proper water management practices can reduce arsenic accumulation. Different water management regimes, such as continuous flooding irrigation, alternate wetting and drying, aerobic rice cultivation, and subsurface drip irrigation, can affect the speciation and methylation of As in rice. Continuous flooding irrigation reduces methylation of As due to anaerobic conditions, while alternate wetting and drying and aerobic rice cultivation promote methylation by creating aerobic conditions that stimulate the activity of arsenic-methylating microorganisms. Subsurface drip irrigation reduces total arsenic content in rice grains and increases the proportion of less toxic methylated arsenic species. The review also discusses the complex mechanisms of As-methylation and transport in rice, emphasizing the importance of understanding these mechanisms to develop strategies for reducing arsenic uptake in rice plants and mitigating health risks. The review addresses the impact of water source and type on arsenic speciation and methylation in rice and highlights the need for proper water management and treatment measures to ensure the safety of the food supply as well as aiding future research and policies to reduce health risks from rice consumption. The critical information gaps that this review addresses include the specific effects of different water management regimes on As-methylation, the role of microbial communities in groundwater in As-methylation, and the potential risks associated with the use of reclaimed water for irrigation.

Organic Remobilization of zinc and phosphorus availability to plants by application of mineral solubilizing bacteria Pseudomonas aeruginosa

Incessant utilization of chemical fertilizers leads to the accumulation of minerals in the soil, rendering them unavailable to plants. Unaware of the mineral reserves present in the soil, farming communities employ chemical fertilizers once during each cultivation, a practice that causes elevated levels of insoluble minerals within the soil. The use of biofertilizers on the other hand, reduces the impact of chemical fertilizers through the action of microorganisms in the product, which dissolves minerals and makes them readily available for plant uptake, helping to create a sustainable environment for continuous agricultural production. In the current investigation, a field trial employing Arachis hypogaea L was conducted to evaluate the ability of Pseudomonas aeruginosa to enhance plant growth and development by solubilizing minerals present in the soil (such as zinc and phosphorus). A Randomized Complete Block Design (RCBD) included five different treatments as T1: Un inoculated Control; T2: Seeds treated with a liquid formulation of P. aeruginosa; T3: Seeds treated with a liquid formulation of P. aeruginosa and the soil amended with organic manure (farmyard); T4: Soil amended with organic manure (farmyard) alone; T5: Seeds treated with lignite (solid) based formulation of P. aeruginosa were used for the study. Efficacy was determined based on the plant's morphological characters and mineral contents (Zn and P) of plants and soil. Survival of P. aeruginosa in the field was validated using Antibiotic Intrinsic patterns (AIP). The results indicated that the combination treatment of P. aeruginosa liquid formulation and organic fertilizer (farmyard) (T3) produced the highest biometric parameters and mineral (Zn and P) content of the groundnut plants and the soil. This outcome is likely attributed to the mineral solubilizing capability of P. aeruginosa. Furthermore, the presence of farmyard manure increased the metabolic activity of P. aeruginosa by inducing its heterotrophic activity, leading to higher mineral content in T3 soil compared to other soil treatments. The AIP data confirmed the presence of the applied liquid inoculant by exhibiting a similar intrinsic pattern between the in vitro isolate and the isolate obtained from the fields. In summary, the Zn and P solubilization ability of P. aeruginosa facilitates the conversion of soil-unavailable mineral form into a form accessible to plants. It further proposes the utilization of the liquid formulation of P. aeruginosa as a viable solution to mitigate the challenges linked to solid-based biofertilizers and the reliance on mineral-based chemical fertilizers.

Temporal groundwater quality, health risks and source point management zonation of multi-aquifers in Jilin Qian'an, Northeastern China

Jilin Qian'an, located in Northeastern China's Songnen Plain, relies almost exclusively on groundwater for drinking. The quaternary phreatic aquifer (Q3) is distinguished by high geogenic fluoride and arsenic concentrations, which necessitates reliance on quaternary confined (Q1) and neogene confined (N) aquifers (deeper aquifers) as source point management (SPM) alternatives. However, deeper aquifers are contaminated, necessitating temporal monitoring and unique management strategies. Using 165 samples, this study investigated the appropriateness of deeper restricted aquifers as a continuous SPM alternative by assessing the spatiotemporal groundwater quality and human health risk of the multi-aquifers in Jilin Qian'an from the 1980s to the 2010s. In addition, a source point management zonation (SPMZ) was implemented to define the specific intervention necessary in various portions of the study area. Results indicate water quality parameters were within recommended limits for most samples except fluoride, while arsenic was the most significant heavy metal pollutant. Mean groundwater mineralization in all the aquifers increased with time. Deeper aquifers are still a better alternative to the shallow phreatic aquifer as groundwater quality in the study is of the order N > Q1 > Q3 in the respective aquifers. Cancer risk assessment (CR) shows increases from 2001 to the 2010s in all aquifers except in Q3. SPMZ delineated: High As and high F zones; high As and low F zones; high As zones; high F zones; low F zones; and safe zones. Localized intervention based on SPMZ is recommended, along with the use of alternative water sources.

Significance of the prime factors regulating arsenic toxicity and associated health risk: a hypothesis-based investigation in a critically exposed population of West Bengal, India

The suffering from arsenic toxicity is a long-standing concern in Asian countries. The role of the key factors (arsenic intake, age and sex) regulating arsenic toxicity is aimed to evaluate for a severely exposed population from Murshidabad district, West Bengal. Mean arsenic concentrations in drinking water supplied through tube well, Sajaldhara treatment plant and pipeline were observed as 208, 27 and 54 µg/l, respectively. Urinary arsenic concentration had been observed as < 3-42.1, < 3-56.2 and < 3-80 µg/l in children, teenagers and adults, respectively. Mean concentrations of hair and nail arsenic were found to be 0.84 and 2.38 mg/kg; 3.07 and 6.18 mg/kg; and 4.41 and 9.07 mg/kg, respectively, for the studied age-groups. Water arsenic was found to be associated with hair and nail (r = 0.57 and 0.60), higher than urine (r = 0.37). Arsenic deposition in biomarkers appeared to be dependent on age; however, it is independent of sex. Principal component analysis showed a direct relationship between dietary intake of arsenic and chronic biomarkers. Nail was proved as the most fitted biomarker of arsenic toxicity by Dunn's post hoc test. Monte Carlo sensitivity analysis and cluster analysis showed that the most significant factor regulating health risk is 'concentration of arsenic' than 'exposure duration', 'body weight' and 'intake rate'. The contribution of arsenic concentration towards calculated health risk was highest in teenagers (45.5-61.2%), followed by adults (47.8-49%) and children (21-27.6%). Regular and sufficient access to arsenic-safe drinking water is an immediate need for the affected population.

Arsenic contamination in groundwater and food chain with mitigation options in Bengal delta with special reference to Bangladesh

Bangladesh, situated in Bengal delta, is one of the worst affected countries by arsenic contamination in groundwater. Most of the people in the country are dependent on groundwater for domestic and irrigation purposes. Currently, 61 districts out of 64 districts of Bangladesh are affected by arsenic contamination. Drinking arsenic contaminated groundwater is the main pathway of arsenic exposure in the population. Additionally, the use of arsenic-contaminated groundwater for irrigation purpose in crop fields in Bangladesh has elevated arsenic concentration in surface soil and in the plants. In many arsenic-affected countries, including Bangladesh, rice is reported to be one of the significant sources of arsenic contamination. This review discussed scenario of groundwater arsenic contamination and transmission of arsenic through food chain in Bangladesh. The study further highlighted the human health perspectives of arsenic exposure in Bangladesh with possible mitigation and remediation options employed in the country.

Arsenic in Drinking Water and Diabetes

Arsenic is ubiquitous in soil and water environments and is consistently at the top of the Agency for Toxic Substances Disease Registry (ATSDR) substance priority list. It has been shown to induce toxicity even at low levels of exposure. One of the major routes of exposure to arsenic is through drinking water. This review presents current information related to the distribution of arsenic in the environment, the resultant impacts on human health, especially related to diabetes, which is one of the most prevalent chronic diseases, regulation of arsenic in drinking water, and approaches for treatment of arsenic in drinking water for both public utilities and private wells. Taken together, this information points out the existing challenges to understanding both the complex health impacts of arsenic and to implementing the treatment strategies needed to effectively reduce arsenic exposure at different scales.

Heavy metal contamination along different tidal zones of a tropical Bay of Bengal coastal environment influenced by various anthropogenic activities

The spatiotemporal variations of five heavy metals (Cd, Cu, Cr, Pb, and Zn) in the beach sediments along the Tamil Nadu coast sourced from various anthropogenic activities were assessed using atomic absorption spectrophotometry (AAS). Various pollution monitoring indices were computed to clearly understand the metal pollution status along the Tamil Nadu coastline. The metal concentrations in sediments were typically higher in the summer season than in the monsoon season. In the monsoon season, metal concentration followed a decreasing order of Zn > Cr > Cu > Pb > Cd, and in the summer season, the order was Cr > Zn > Cu > Pb > Cd. During the monsoon season, freshwater runoff from the rainfall dilutes the sediments and their trace element load. However, due to a lack of freshwater influx during the summer season, the heavy metals in the sediments get concentrated and showed elevated levels. Geo-accumulation index, ecological risk index, pollution load index, and contamination degree clearly depict that Cd and Pb have higher accumulation and pose greater hazard when compared with other metals. The rivers flowing in the region also transport the heavy metals from the mainland to the estuaries and coastal environments. Metal levels along the Tamil Nadu coast are influenced by various anthropogenic activities persistent along the coastline. Some of the activities that cause metal contamination are mining, milling, electroplating, furnishing, pharmaceutical industries, fishing, harbor activities, urban runoff, and agricultural runoff, which release a variety of toxic metals into the coastal environment.

Changes in arsenic accumulation and metabolic capacity after environmental management measures in mining area

Due to the public health concern of arsenic, environmental management measures in mining areas had been implemented. To assess the effect of environmental management measures in the mining area comprehensively, arsenic accumulation in the urine, hair, nails, and urinary metabolites of residents in a realgar mining area in Hunan province, China were investigated in 2019, and the changes in arsenic levels in the biomarkers during 2012-2019 were tracked. The importance of confounding factors (age, sex, occupation, residence, clinical history, vegetable source, cooking fuel, smoking, alcohol consumption, BMI) was analyzed using the Boruta algorithm. After the implementation of environmental management measures (including ceasing mining and smelting activities, building landfills, adjusting the planting structure, and soil restoration), urine, hair, and nail arsenic concentration decreased drastically but were still excessive. Arsenic accumulation was highest in older male miners who were long settled in the mining area and consumed homegrown vegetables. The only factor for changes in urinary arsenic levels was the cooking fuel type; residents using wood as cooking fuel experienced sustained arsenic exposure. Occupation and sex were important for determining arsenic changes in the hair and nails. Short-term arsenic accumulation in urine was affected by arsenic exposure, while long-term accumulation in hair and nails by arsenic metabolic capacity. The percentage of urinary arsenic metabolism and arsenic methylation indices of the participants in the mining area were within the normal range (%iAs: 10-30 %, %MMA: 10-20 %, % DMA: 60-80 %); samples indicated worse metabolic capacity than the reference population. The arsenic metabolic capacity of male miners was relatively weak, probably aggravated by alcohol drinking and smoking. Without soil remediation, arsenic exposure will continue. Homegrown vegetables and biomass fuels should be abandoned; reduced cigarette and alcohol consumption is recommended. Urinary arsenic would be more proper for assessing environmental remediation in mining areas.

The dark side of NRF2 in arsenic carcinogenesis

Arsenic is an environmental toxicant that significantly enhances the risk of developing disease, including several cancers. While the epidemiological evidence supporting increased cancer risk due to chronic arsenic exposure is strong, therapies tailored to treat exposed populations are lacking. This can be accredited in large part to the chronic nature and pleiotropic pathological effects associated with prolonged arsenic exposure. Despite this fact, several putative mediators of arsenic promotion of cancer have been identified. Among these, the critical transcription factor NRF2 has been shown to be a key mediator of arsenic's pro-carcinogenic effects. Importantly, the dependence of arsenic-transformed cancer cells on NRF2 upregulation exposes a targetable liability that could be utilized to treat arsenic-promoted cancers. In this chapter, we briefly introduce the "light" vs "dark" side of the NRF2 pathway. We then give a brief overview of arsenic metabolism, and discuss the epidemiological and experimental evidence that support arsenic promotion of different cancers, with a specific emphasis on mechanisms mediated by chronic, non-canonical activation of NRF2 (i.e., the "dark" side). Finally, we briefly highlight how the non-canonical NRF2 pathway plays a role in other arsenic-promoted diseases, as well as research directions that warrant further investigation.

Exploring mitigating role of zinc nanoparticles on arsenic, ammonia and temperature stress using molecular signature in fish

BACKGROUND

The pollution and climate change in aquatic ecosystems are major problems threatening the aquatic organisms for existence in the recent timeline, which promotes the extinction of the fish species. However, the present study dealt with zinc nanoparticles (Zn-NPs) in mitigating arsenic, ammonia and high temperature stresses in Pangasianodon hypophthalmus.

MATERIALS AND METHODS

To studying different gene expressions, an experiment was conducted to mitigate the multiple stressors using dietary Zn-NPs at 0, 2, 4, and 6 mg kg^-1 diets. In the present investigation, the gene expressions studies were performed for growth hormone regulator 1 (GHR1), growth hormone regulator β (GHRβ), growth hormone (GR) in liver and gill tissue as well as myostatin (MYST) and somatostatin (SMT) in the muscle tissue. The anti-oxidative genes CAT, SOD and GPx in liver and gill tissues were also analysed. Expression studies for stress responsive heat shock protein gene (HSP70), DNA damage inducible protein, inducible nitric oxide synthase (iNOS), immune related genes such as interleukin (IL), tumour necrosis factor (TNFα), toll like receptor (TLR) and immunoglobulin were performed. At the end of the experiment the fish were infected with Aeromonas hydrophila to evaluate the immunomodulatory role of Zn-NPs.

RESULTS

In the present investigation, the growth hormone regulator 1 (GHR1), growth hormone regulator β (GHRβ), growth hormone (GR) in liver and gill as well as myostatin (MYST) and somatostatin (SMT) in muscle were noticeably altered, whereas, Zn-NPs at 4 mg kg^-1 diet improved gene expressions. The anti-oxidant gene viz. CAT, SOD and GPx in liver and gill tissues were upregulated by stressors such as As, NH₃, NH₃+T. As+T and As+NH₃+T. Therefore, anti-oxidant genes were noticeably improved with dietary Zn-NPs diet. The stress protein gene (HSP70), DNA damage inducible protein, inducible nitric oxide synthase (iNOS) was significantly upregulated, whereas, Zn-NPs diet was applied to the corrected gene regulation. Similarly, immune related genes such as interleukin (IL), tumour necrosis factor (TNFα), toll like receptor (TLR) and immunoglobulin were highly affected by stressors. Dietary Zn-NPs at 4 mg kg^-1 diet was improved all the immune related gene expression and mitigate arsenic, ammonia and high temperature stress in fish.

CONCLUSION

The present investigation revealed that Zn-NPs at 4.0 mg kg^-1 diet has enormous potential to modulates arsenic, ammonia and high temperature stress, and protect against pathogenic infections in fish.

Inherited genetic effects on arsenic metabolism: A comparison of effects on arsenic species measured in urine and in blood

Inorganic arsenic (iAs) is a carcinogen, and chronic exposure is associated with adverse health outcomes, including cancer and cardiovascular disease. Consumed iAs can undergo two methylation reactions catalyzed by arsenic methyltransferase (AS3MT), producing monomethylated and dimethylated forms of arsenic (MMA and DMA). Methylation of iAs helps facilitate excretion of arsenic in urine, with DMA composing the majority of arsenic species excreted. Past studies have identified genetic variation in the AS3MT (10q24.32) and FTCD (21q22.3) regions associated with arsenic metabolism efficiency (AME), measured as the proportion of each species present in urine (iAs%, MMA%, and DMA%), but their association with arsenic species present in blood has not been examined. We use data from three studies nested within the Health Effects and Longitudinal Study (HEALS)-the Nutritional Influences on Arsenic Toxicity Study, the Folate and Oxidative Stress study, and the Folic Acid and Creatine Trial-to examine the association of previously identified genetic variants with arsenic species in both urine and blood of 334 individuals. We confirm that the genetic variants in AS3MT and FTCD known to effect arsenic species composition in urine (an excreted byproduct of metabolism) have similar effects on arsenic species in blood (a tissue type that directly interacts with many organs, including those prone to arsenic toxicity). This consistency we observe provides further support for the hypothesis the AME SNPs identified to date impact the efficiency of arsenic metabolism and elimination, thereby influencing internal dose of arsenic and the dose delivered to toxicity-prone organs and tissues.

Human health impact due to arsenic contaminated rice and vegetables consumption in naturally arsenic endemic regions

Rice and vegetables cultivated in naturally arsenic (As) endemic areas are the substantial source of As body loading for persons using safe drinking water. However, tracing As intake, particularly from rice and vegetables by biomarker analysis, has been poorly addressed. This field investigation was conducted to trace the As transfer pathway and measure health risk associated with consuming As enriched rice and vegetables. Purposively selected 100 farmers from five sub-districts of Chandpur, Bangladesh fulfilling specific requirements constituted the subjects of this study. A total of 100 Irrigation water, soils, rice, and vegetable samples were collected from those farmers' who donated scalp hair. Socio-demographic and food consumption data were collected face to face through questionnaire administration. The mean As level in irrigation water, soils, rice, vegetables, and scalp hairs exceeded the acceptable limit, while As content was significant at 0.1%, 5%, 0.1%, 1%, and 0.1% probability levels, respectively, in all five locations. Arsenic in scalp hair is significantly (p ≤ 0.01) correlated with that in rice and vegetables. The bioconcentration factor (BCF) for rice and vegetables is less than one and significant at a 1% probability level. The average daily intake (ADI) is higher than the RfD limit for As. Both grains and vegetables have an HQ (hazard quotient) > 1. Maximum incremental lifetime cancer risk (ILCR) showed 2.8 per 100 people and 1.6 per 1000 people are at considerable and threshold risk, respectively. However, proteinaceous and nutritious food consumption might have kept the participants asymptomatic. The PCA analysis showed that the first principle component (PC1) explains 91.1% of the total variance dominated by As in irrigation water, grain, and vegetables. The dendrogram shows greater variations in similarity in rice and vegetables As, while the latter has been found to contribute more to human body loading compared to grain As.

Household and community systems for groundwater remediation in Bihar, India: Arsenic and inorganic contaminant removal, controls and implications for remediation selection

The presence of arsenic (As) and other inorganic contaminants in groundwater is a key public health issue in India and many other parts of the world. Whilst a broad range of remediation technologies exist, performance can be highly variable, and appropriate selection and management of remediation approaches remains challenging. Here, we have identified and tested the performance of a range of small-scale remediation technologies (e.g. sand filters, multi-stage filtration and reverse osmosis (RO)-based systems; n = 38) which have been implemented in Bihar, India. We have undertaken spot-assessments of system performance under typical operating conditions in household and non-household (e.g. community, hospital, hostel/hotel) settings. The removal of As and other inorganic contaminants varied widely (ranging from ~0-100%), with some solutes generally more challenging to remove than others. We have evaluated the relative importance of technology type (e.g. RO-based versus non-RO systems), implementation setting (e.g. household versus non-household) and source water geochemistry (particularly concentrations and ratios of As, Fe, P, Si and Ca), as potential controls on remediation effectiveness. Source water composition, particularly the ratio ([Fe] - 1.8[P])/[As], is a statistically significant control on As removal (p < 0.01), with higher ratios associated with higher removal, regardless of technology type (under the site-specific conditions observed). This ratio provides a theoretical input which could be used to identify the extent to which natural groundwater composition may be geochemically compatible with higher levels of As removal. In Bihar, we illustrate how this ratio could be used to identify spatial patterns in theoretical geochemical compatibility for As removal, and to identify where additional Fe may theoretically facilitate improved remediation. This geochemical approach could be used to inform optimal selection of groundwater remediation approaches, when considered alongside other important considerations (e.g. technical, managerial and socio-economic) known to impact the effective implementation and sustainability of successful groundwater remediation approaches.

Hydrogeochemical and health risk assessment in and around a Ramsar-designated wetland, the Ganges River Basin, India: Implications for natural and human interactions

Wetlands are the most productive and dynamic ecosystems, which have continuously been influenced by social and economic development. As a result, the pollution of wetland surface water and groundwater in adjacent regions has become an emerging global issue that requires constant monitoring and assessment. The current study investigates the natural and anthropogenic processes that influence surface and groundwater chemistry in and around Saman wetland (a Ramsar site) in the Ganges River Basin, India. Various physicochemical parameters are analyzed, and different hydrochemical indices are utilized to evaluate surface and groundwater quality for domestic and irrigation purposes. It is observed that the waters are alkaline in nature and dominated by moderately hard to hard types. An increase in the concentration of nitrate (NO₃^-) in Saman wetland water is noted, which is possibly due to the leaching of nitrogen ions primarily from fertilizers, pesticides, animal and human waste, and wastewater drained from brick and other factories. The elevated fluoride (F^-) content in studied groundwater samples is mainly governed by geogenic processes. Furthermore, surface and groundwater chemistry are mainly controlled by weathering reaction (rock-water interaction), excluding a few wetland surface water samples that are placed outside the boomerang-shaped boundaries of Gibb's diagram, which suggests evaporated dominance. Water Quality Index (WQI) estimation suggests that around 57% of groundwater samples have poor groundwater quality for drinking purposes. Estimation of irrigation water quality indices suggests that surface water of Saman wetland is permissible for irrigation purposes; however, none of the samples have excellent and good class as per sodium (alkali) hazard. Furthermore, health risk assessment showed that NO₃^- and F^- levels in the groundwater pose noncarcinogenic health effects, preferably to children, and thus is unfit for drinking purposes. For long-term water resource management and conservation of the Saman wetland, this study suggests proper awareness, appropriate remedial measures, and regular monitoring of the surface as well as groundwater quality monitoring in the study region.

Effects of carnosic acid on arsenic-induced liver injury in mice: A comparative transcriptomics analysis

BACKGROUND

Long-term chronic exposure to arsenic can cause different degrees of liver injury. Till date, its molecular mechanism has not meant fully elucidated. Evidence indicates that Carnosic acid (CA) has a protective role in arsenic-induced liver injury. This study aimed to reveal the potential targets and evaluate the potential effect of CA intervention at transcriptional level, and provide reference for the intervention of arsenic-induced liver injury.

METHODS

Arsenic-induced liver injury and CA intervention models were established in C57BL/6 mice. RNA sequencing technique was carried out to obtain the differentially expressed gene (DEG) profiles. The common covariant DEGs between arsenic induction and CA intervention was screened by comparative transcriptomic analysis methods. QRT-PCR was used to verify the covariant DEGs.

RESULTS

Transcriptome results showed that 220 DEGs were identified after arsenic induction. 267 DEGs were identified after CA intervention (|fold change| > 2.0 and adjusted P < 0.05). 42 covariant DEGs were discovered between the comparison of "AS vs Control" and "AS & CA vs AS". In addition, hub gene analysis revealed a total of 8 covariant DEGs (Ehhadh, Fgf21, Cyp2b10, Plin2, Aacs, Cyp7a1, Per2 and Mylip). The mRNA expressions of Fgf21 and Plin2 were significantly increased (P < 0.05) and the mRNA expressions of Cyp2b10, Cyp7a1, Per2 and Mylip were significantly decreased (P < 0.05) after arsenic induction. On the contrary, the changes of these DEGs were reversed after CA intervention.

CONCLUSION

The present study would be helpful to understand the potential health effects of arsenic-induced liver injury and identify new potential targets, and provide a reference for the intervention of CA.

Removal of As(V) from wastewaters using magnetic iron oxides formed by zero-valent iron electrocoagulation

Electrocoagulation of zero-valent iron has been widely applied to the removal of dissolved arsenic, but the solid-liquid separation of arsenic-containing precipitates remains technically challenging. In this work, zero-valent iron was electrochemically oxidized to magnetic iron oxides for the removal of As(Ⅴ) from simulated and actual mining wastewaters. The results indicated that lepidocrocite was formed when zero-valent iron was oxidized by dissolved oxygen, but ferrihydrite and green rust were first formed and then transformed to magnetic iron oxides (mainly magnetite and maghemite) in the electrochemical oxidation from 0 to 0.9 V (vs. SCE), which facilitates the adsorption of As(V) and subsequent solid-liquid separation under a magnetic field. In simulated As(V)-containing solution with initial pH 7.0, zero-valent iron was electrochemically oxidized to magnetite and maghemite at 0.6 V (vs. SCE) for 2 h. The As(V) concentration first decreased from 5127.5 to 26.8 μg L^-1 with a removal ratio of 99.5%. In actual mining wastewaters, zero-valent iron was electrochemically oxidized to maghemite at 0.6 V (vs. SCE) for 24 h, and the As(V) concentration decreased from 5486.4 to 3.6 μg L^-1 with a removal ratio of 99.9%. The removal ratio of As(V) increased slightly with increasing potential, and increased first and then decreased with increasing initial pH. Compared with that of SO₄^2- and NO₃^-, the presence of Cl^- significantly enhanced the removal of As(V). This work provides a highly efficient, facile and low-cost technique for the treatment of arsenic-containing wastewaters.

Assessment of disease burden in the arsenic exposed population of Chapar village of Samastipur district, Bihar, India, and related mitigation initiative

Fast growing arsenic menace is causing serious health hazards in Bihar, India, with an estimated 10 million people at risk. The exposed population is often unaware of the problem, which only amplifies the burden of arsenic health effects. In the present study, we have assessed the current situation of arsenic exposure in Chapar village of Samastipur district, Bihar. The health of the inhabitants was assessed and correlated with (1) arsenic concentrations in the groundwater of individual wells and (2) arsenic concentration found in their hair and urine. Altogether, 113 inhabitants were assessed, and 113 hair, urine and groundwater samples were collected. The health study reveals that the exposure to arsenic has caused serious health hazard amongst the exposed population with pronounced skin manifestations, loss of appetite, anaemia, constipation, diarrhoea, general body weakness, raised blood pressure, breathlessness, diabetes, mental disabilities, diabetes, lumps in the body and few cancer incidences. It was found that 52% of the total collected groundwater samples had arsenic levels higher than the WHO limit of 10 µg/l (with a maximum arsenic concentration of 1212 µg/l) and the reduced arsenite was the predominant form in samples tested for speciation (N = 19). In the case of hair samples, 29% of the samples had arsenic concentrations higher than the permissible limit of 0.2 mg/kg, with a maximum arsenic concentration of 46 µg/l, while in 20% exposed population, there was significant arsenic contamination in urine samples > 50 µg/l. In Chapar village, the probability of carcinogenic-related risk in the exposed population consuming arsenic contaminated water is 100% for children, 99.1% for females and 97.3% for male subjects. The assessment report shared to the government enabled the village population to receive two arsenic filter units. These units are currently operational and catering 250 households providing arsenic-free water through piped water scheme. This study therefore identified a significant solution for this arsenic-exposed population.

The stability of poorly crystalline arsenical ferrihydrite after long-term soil suspension incubation

2- Line ferrihydrite (Fh) is widely used as a robust amendment for rapid arsenic removal or remediation in water or soil. However, the poorly crystalline phase of Fh is unstable and leads to arsenic leaching after long-term submergence in reductive aquatic and soil environments. In this study, the synthesized As(V)-bound Fh was characterized by various spectral approaches to investigate the factors that may affect the variation in As(V)-Fh in long-term continuously submerged soil suspensions. The X-ray diffraction (XRD) results showed that hematite was the main product and that goethite was the byproduct after 360 d of incubation. Approximately 12-17% and 4-5% Fh were transformed at As/Fe mole ratios of 0.005 and 0.05, respectively. After 360 d of incubation, the hematite morphology was clearly observed by scanning electron microscopy (SEM), and the As(V)-Fh surface areas were also decreased by 17.3-27.6% and 11.9-16.6% for As/Fe mole ratios of 0.005 and 0.05, respectively. In a comparison of the two tested soils (soils sampled in Sichuan Province (SC) and Hunan Province (HN)), As(V)-Fh transformed faster in HN soil suspensions, and more hematite and goethite were formed. Furthermore, during the incubation period, As(V) was transformed to As(III), and both species were released into the suspension from the As(V)-Fh surface. It was suggested that soil pH and Fe(II) concentration were key factors controlling the As(V)-Fh transformation process, and the differences between the two soils were due to the different soil pH values and contents of available Fe. Arsenic release was mainly caused by Fh transformation and ligand competition with soil organic matter (SOM).

Nanomaterials as adsorbents for As(III) and As(V) removal from water: A review

Freshwater demand will rise in the next couple of decades, with an increase in worldwide population growth and industrial development. The development activities, on one side, have increased the freshwater demand. However, the ground water has been degraded. Among the various organic and inorganic contaminants, arsenic is one of the most toxic elements. Arsenic contamination in ground waters is a major issue worldwide, especially in South and Southeast Asia. Various methods have been applied to provide a remedy to arsenic contamination, including adsorption, ion exchange, oxidation, coagulation-precipitation and filtration, and membrane filtration. Out of these methods, adsorption of As(III)/As(V) using nanomaterials and biopolymers has been used on a wide scale. The present review focuses on recently used nanomaterials and biopolymer composites for As(III)/As(V) sorptive removal. As(III)/As(V) adsorption mechanisms have been explored for various sorbents. The impacts of environmental factors such as pH and co-existing ions on As(III)/As(V) removal, have been discussed. Comparison of various nanosorbents and biopolymer composites for As(III)/As(V) adsorption and regeneration of exhausted materials has been included. Overall, this review will be useful to understand the sorption mechanisms involved in As(III)/As(V) removal by nanomaterials and biopolymer composites and their comparative sorption performances.

Comparison of concentrations of toxic elements in the hair of first-year students of RUDN University from different regions of the world: a cross-sectional study

Due to the development of the metallurgical and energy industries and the operation of incinerators, more and more environmental pollution is occurring. Toxic elements accumulate in the biosphere and affect the state of the population of the regions of large-scale production or the disposal of industrial waste. The main goal of this study was to compare the toxic elements hair composition in people from different regions of the world. The concentrations of toxic and potentially toxic elements (Al, As, Be, Cd, Hg, Pb, Sn) in 198 people, first-year students of People's Friendship University of Russia, who arrived from different regions of the world, were measured with inductively coupled plasma mass spectrometry. Students were divided into 6 groups: from South and East Asia, from Latin America, from Arab countries, Central Asia and Afghanistan, from South and Central Africa, from Iran and Azerbaijan, and from Russia, Ukraine, and Moldova. Medians of the concentrations of elements in the hair in the general group were 5.8 μg/g for Al, 30 ng/g for As, 0.6 ng/g for Be, 9.0 ng/g for Cd, 0.11 μg/g for Hg, 0.24 μg/g for Pb, and 0.11 μg/g for Sn. All these values fall within the normal range. Students from Russia, Moldova, and Ukraine showed a significantly higher Sn content (0.28 μg/g) in their hair than subjects from other regions except for Latin America, p<0,05. Except for As, cases of exceeding their recommended concentrations in the hair were identified. However, the proportion of subjects with deviations in each group was not high - not more than 7%. In all regions, a positive correlation was found between Cd, Pb, and Sn, p<0.05, r>0.5 for all. Cases of exceeding the maximum permissible concentrations of various toxic elements in the hair were detected in people from all regions of the Earth included in the study. And although the overall picture of the content of toxic elements in the hair of students from all regions in our study does not look critical, the results of previous studies, as well as information about the total deterioration of the environmental situation throughout the Earth, necessitate further large-scale environmental studies.

Heavy Metal Contamination of Natural Foods Is a Serious Health Issue: A Review

Heavy metals play an important role in the homeostasis of living cells. However, these elements induce several adverse environmental effects and toxicities, and therefore seriously affect living cells and organisms. In recent years, some heavy metal pollutants have been reported to cause harmful effects on crop quality, and thus affect both food security and human health. For example, chromium, cadmium, copper, lead, and mercury were detected in natural foods. Evidence suggests that these elements are environmental contaminants in natural foods. Consequently, this review highlights the risks of heavy metal contamination of the soil and food crops, and their impact on human health. The data were retrieved from different databases such as Science Direct, PubMed, Google scholar, and the Directory of Open Access Journals. Results show that vegetable and fruit crops grown in polluted soil accumulate higher levels of heavy metals than crops grown in unpolluted soil. Moreover, heavy metals in water, air, and soil can reduce the benefits of eating fruits and vegetables. A healthy diet requires a rational consumption of foods. Physical, chemical, and biological processes have been developed to reduce heavy metal concentration and bioavailability to reduce heavy metal aggregation in the ecosystem. However, mechanisms by which these heavy metals exhibit their action on human health are not well elucidated. In addition, the positive and negative effects of heavy metals are not very well established, suggesting the need for further investigation.

Molecular Mechanism of Arsenic-Induced Neurotoxicity including Neuronal Dysfunctions

Arsenic is a key environmental toxicant having significant impacts on human health. Millions of people in developing countries such as Bangladesh, Mexico, Taiwan, and India are affected by arsenic contamination through groundwater. Environmental contamination of arsenic leads to leads to various types of cancers, coronary and neurological ailments in human. There are several sources of arsenic exposure such as drinking water, diet, wood preservatives, smoking, air and cosmetics, while, drinking water is the most explored route. Inorganic arsenic exhibits higher levels of toxicity compared its organic forms. Exposure to inorganic arsenic is known to cause major neurological effects such as cytotoxicity, chromosomal aberration, damage to cellular DNA and genotoxicity. On the other hand, long-term exposure to arsenic may cause neurobehavioral effects in the juvenile stage, which may have detrimental effects in the later stages of life. Thus, it is important to understand the toxicology and underlying molecular mechanism of arsenic which will help to mitigate its detrimental effects. The present review focuses on the epidemiology, and the toxic mechanisms responsible for arsenic induced neurobehavioral diseases, including strategies for its management from water, community and household premises. The review also provides a critical analysis of epigenetic and transgenerational modifications, mitochondrial oxidative stress, molecular mechanisms of arsenic-induced oxidative stress, and neuronal dysfunction.

Influence of low temperature on comparative arsenic accumulation and release by three Pteris hyperaccumulators

Arsenic (As) hyperaccumulator Pteris ferns are renowned for their capacity to accumulate As and have been used to remediate As-contaminated environmental. However, there is less information on how they perform under low temperature though it is important for practical phytoremediation. The purpose of this study was to identify the effect of temperature on As accumulation by three As hyperaccumulators, Pteris multifida, Pteris cretica and Pteris vittata. Ferns were cultured with 5 mg/L As addition under 25 °C to 5 °C for 15 days. The results showed that dropping of temperatures reduced As accumulation by P. vittata moderately but not P. multifida and P. cretica until 10 °C. At 5 °C, all ferns discontinued As accumulation, and the morphology showed necrosis in P. vittata, wherein P. multifida and P. cretica kept healthy. The As distribution showed that As was mainly accumulated in fronds, while P. multifida stored partial As in its root. Both translocation factor and As efflux showed that temperate zone ferns manage As more strictly as compared to P. vittata. Our findings demonstrated that temperature should be considered when applying Pteris ferns for As phytoremediation, and P. multifida could be the most suitable fern for treating As-contaminated water in temperate zone area.

Assessment of arsenic exposure in the population of Sabalpur village of Saran District of Bihar with mitigation approach

Arsenic poisoning through groundwater is the world's greatest normal groundwater catastrophe which got an immense effect on worldwide general wellbeing. India is confronting the outcomes of arsenic poisoning in the zone of Ganga Brahmaputra alluvial plains. In Bihar, out of 38 districts, 18 districts are exceptionally influenced with groundwater arsenic defilement. In the present study, we have assessed the current situation of arsenic exposure in Sabalpur village of Saran district of Bihar after reporting of breast, renal, skin and thyroid cancer cases from this village along with typical symptoms of arsenicosis. Such cancer patients were identified at our institute and were taken for the study. The present investigation deals with the quantification of arsenic in groundwater, hair and nail samples of subjects as well as the survey of entire village to know the overall health status of the village people. A total of n=128 household handpump water samples as well as n=128 human hair and nail samples were collected from over n=520 households. Using the graphite furnace atomic absorption spectrophotometer (GF-AAS), all the samples were analysed. The investigation resulted that the 61% of the analysed samples particularly the groundwater had the arsenic levels more than the permissible limit of WHO (> 10 μg/L) with 244.20 μg/L as the highest arsenic contamination in one of the handpump water sample. The exposure effect of hair sample was worst as 88% of all the collected samples were having high arsenic levels more than the permissible limit (> 0.2 mg/Kg). In case of nail samples, 92% of the samples were having high arsenic concentration more than the permissible limit (> 0.5 mg/Kg). The health survey study revealed high magnitude of disease burden in the exposed population with symptoms such as asthma, anaemia, hepatomegaly, diabetes, cardiac problem, skin fungal infections, breathlessness and mental disability. Few cancer cases of renal, skin, breast and cervix were also found among the exposed population of this village. The percentage of cancer cases in this village was 0.94% that was low, but it would be an aggravated situation in the near future if people will continue drinking arsenic-contaminated water. Therefore, a mitigation intervention was carried out in March 2020 by installing an arsenic filter plant. The health situation in the village in the present scenario is hope to improve in the coming years. However, motivation and awareness among the village population are still required.

Health effect and risk assessment of the populations exposed to different arsenic levels in drinking water and foodstuffs from four villages in arsenic endemic Gaighata block, West Bengal, India

Health exposure and perception of risk assessment have been evaluated on the populations exposed to different arsenic levels in drinking water (615, 301, 48, 20 µg/l), rice grain (792, 487, 588, 569 µg/kg) and vegetables (283, 187, 238, 300 µg/kg) from four villages in arsenic endemic Gaighata block, West Bengal. Dietary arsenic intake rates for the studied populations from extremely highly, highly, moderately, and mild arsenic-exposed areas were 56.03, 28.73, 11.30, and 9.13 μg/kg bw/day, respectively. Acute and chronic effects of arsenic toxicity were observed in ascending order from mild to extremely highly exposed populations. Statistical interpretation using 'ANOVA' proves a significant relationship between drinking water and biomarkers, whereas "two-tailed paired t test" justifies that the consumption of arsenic-contaminated dietary intakes is the considerable pathway of health risk exposure. According to the risk thermometer (SAMOE), drinking water belongs to risk class 5 (extremely highly and highly exposed area) and 4 (moderately and mild exposed area) category, whereas rice grain and vegetables belong to risk class 5 and 4, respectively, for all the differently exposed populations. The carcinogenic (ILCR) and non-carcinogenic risks (HQ) through dietary intakes for adults were much higher than the recommended threshold level, compared to the children. Supplementation of arsenic-safe drinking water and nutritional food is strictly recommended to overcome the severe arsenic crisis.

Stability, preservation and storage of As(iii), DMA, MMA and As(v) in water samples

Correct handling and preservation of water samples is crucial to ensure their integrity for arsenic speciation measurements. ISO TS 19620:2018 is a method for the determination of arsenic(iii) and arsenic(v) species in waters by liquid chromatography (LC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) or hydride generation atomic fluorescence spectrometry (HG-AFS). During the development of this method, a study was performed to establish the best practices for storage and preservation of samples to maintain the integrity of the arsenic speciation and stability. Four arsenic species were studied: arsenite (As(iii)), arsenate (As(v)), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in three different water types: deionised water, mineral water and natural river water. The effect of sample bottle material, light, storage temperature, and acidification were evaluated. When samples are acidified and refrigerated, they can reliably be stored for up to 12 weeks without significantly affecting the arsenic concentration and speciation. The sample bottle material and light had no affect on the speciation integrity or stability.

Geostatistical model of the spatial distribution of arsenic in groundwaters in Gujarat State, India

Geogenic arsenic contamination in groundwaters poses a severe health risk to hundreds of millions of people globally. Notwithstanding the particular risks to exposed populations in the Indian sub-continent, at the time of writing, there was a paucity of geostatistically based models of the spatial distribution of groundwater hazard in India. In this study, we used logistic regression models of secondary groundwater arsenic data with research-informed secondary soil, climate and topographic variables as principal predictors generate hazard and risk maps of groundwater arsenic at a resolution of 1 km across Gujarat State. By combining models based on different arsenic concentrations, we have generated a pseudo-contour map of groundwater arsenic concentrations, which indicates greater arsenic hazard (> 10 μg/L) in the northwest, northeast and south-east parts of Kachchh District as well as northwest and southwest Banas Kantha District. The total number of people living in areas in Gujarat with groundwater arsenic concentration exceeding 10 μg/L is estimated to be around 122,000, of which we estimate approximately 49,000 people consume groundwater exceeding 10 µg/L. Using simple previously published dose-response relationships, this is estimated to have given rise to 700 (prevalence) cases of skin cancer and around 10 cases of premature avoidable mortality/annum from internal (lung, liver, bladder) cancers-that latter value is on the order of just 0.001% of internal cancers in Gujarat, reflecting the relative low groundwater arsenic hazard in Gujarat State.

Progress in the prevention and control of water-borne arsenicosis in China

In this report, we provided an overview of the prevalence, control, and prevention of water-borne arsenicosis in China during 2001-2016. Random sampling was continuously performed during 2001-2010 to find villages having high levels of arsenic (>50 µg/L) in drinking water. The high-arsenic-exposure villages with more geographically dispersed water supplies were subsequently analyzed for characteristics of arsenic distribution, and villages with relatively large populations were investigated for arsenicosis. The results showed that among 32,673,677 inhabitants in 36,820 villages, 1,894,587 inhabitants in 2,476 villages were at risk of high arsenic exposure. Among the 33,318 drinking water sources surveyed in 625 high-arsenic-exposure villages, 9,807 drinking water sources that contained high levels of arsenic (>50 µg/L) were identified. The overall prevalence rate of arsenicosis was 1.93%. Further, some representative villages were chosen to monitor arsenicosis annually, showing that the prevalence rate of arsenicosis was lower in villages with arsenic-safe water supplies than in villages without arsenic-safe water supplies. To the best of our knowledge, this report provides the most comprehensive assessment of the distribution of high arsenic exposure and arsenicosis in China until now.

Sensing Atrazine Herbicide Degradation Products through Their Interactions with Humic Substances by Surface-Enhanced Raman Scattering

In this work, we have developed a simple method to carry out the quantitative analysis of deethylhydroxyatrazine (DEHA), the most abundant metabolite of atrazine herbicide (ATZ), based on the surface-enhanced Raman scattering technique. Since this ATZ product can undergo pH-dependent tautomerization, a previous characterization of the DEHA vibrational spectrum was accomplished. This study consisted of the Raman scattering study, both experimental and theoretical, of the enolic and ketonic tautomers of this molecule. SERS spectra were recorded at different pH in order to assess the effect of the metal surface in nanoparticles along with the pH on the structure of DEHA and to find the optimal experimental conditions of the quantitative detection of DEHA. Additionally, the interaction of DEHA with two types of humic acid reference standards, the Elliot humic and leonardite humic ones, was also performed by SERS. This interaction was conducted with two different objectives: to evaluate the interaction mechanism of the ATZ degradation product with humic substances and to check if this interaction can modify the sensitivity of the SERS detection of DEHA. The results presented in this study have clearly demonstrated that SERS spectroscopy is a very powerful technique for characterizing DEHA and other triazine sub-products at a very low concentration in water and also for analyzing the interaction of these important pollutants with humic substances.

Residual pollutants in treated pulp paper mill wastewater and their phytotoxicity and cytotoxicity in Allium cepa

Discharged pulp and paper mill wastewater (PPMW) were collected near M/s K. R. pulp and papers Limited, Shahjahanpur, India. Chemical analysis of the wastewater showed high BOD (3653-4180 mg L^-1) and COD (17,890-19100 mg L^-1) values from two different sampling sites. The levels of total phenol were in the range of 389-432 mg L^-1; nitrogen (125-234 mg L^-1), sulfate (1926-2098 mg L^-1), chloride (3.12-5.43 mg L^-1) and lignin (38,950-39,000 mg L^-1) along with various heavy metals (Fe, 87-79; Zn, 34-22; Cu, 3.28-2.57; Cd, 1.90-0.36; Ni, 6-5, and Pb, 41.23-36.54 mg L^-1) were above the permissible limits recommended by the CPCB and the USEPA. The BOD/COD ratio was  < 0.2 which indicated very low biodegradability of the organic matters present in the effluent. The organometallic complex generated from the pulp and paper industry persists in the environment and might be toxic to aquatic organisms. The organic polymers, lignin, metals and ions present in the PPMW were characterized using SEM, EDAX, FTIR, and UV-VIS spectroscopy. The major pollutants detected in the discharged PPMW included nonacosane, heptacosane, octadecanoic acid, hexadecane, and 6-benzamide- 3- [2- [1-(phenylmethyl)-4-piperidinyl] ethyl]-1, 2-benzisoxazole, as well as a group of plant fatty acids classified as EDCs, and mutagenic pollutants. The cytotoxic and androgenic properties of these complex organics were examined. The seed germination test with Phaseolus mungo and cytotoxicity test with Allium cepa showed that at > 20% concentration of PPMW, α-amylase production was inhibited and chromosomal segregation at metaphase and anaphase during cell division was disturbed, which resulted in c-mitosis, sticky chromosomes, and laggard chromosomes. In addition, SEM of the root of A. cepa showed fissures and fractured tissues of the root cap, probably due to the inhibition of auxins that were responsible for root cap formation. The findings indicated A. cepa as a good test model for examining the DNA damage and cytotoxicity by PPMW, and the discharged effluent should be treated at a tertiary stage for environmental protection.

Scalable synthesis and purification of functionalized graphene nanosheets for water remediation

Microwave (MW) accelerated synthesis combined with microfiltration (MF) on commercial hollow fiber modules enables fast and scalable preparation of highly pure modified graphene oxide nanosheets. The MW-MF procedure is demonstrated on polyethylenimine (PEI) modified GO, and the so-obtained GOPEI is used for simultaneous removal of arsenic and lead from water.

Therapeutic effects of biochanin A, phloretin, and epigallocatechin-3-gallate in reducing oxidative stress in arsenic-intoxicated mice

One of the most common toxicant prevailing in our environment is the arsenic. The present study is an attempt to investigate the effects of some of the common flavonoids, such as biochanin A (BCA), phloretin, and epigallocatechin-3-gallate (EGCG), on arsenic toxicity in the Swiss albino mice. For this purpose, mice were orally treated with sodium meta-arsenite (20 mg/kg bw/day), along with co-administration of BCA (50 mg/kg bw/day), phloretin (50 mg/kg bw/day), and EGCG (40 mg/kg bw/day) for the 2-week duration. All the mice were euthanized at the end of the treatment period, and the observations were made in the following parameters. Arsenic reduced the sperm motility as compared with the control (p < 0.05) and was restored back to the normal status with the flavonoids treatment significantly (p < 0.05). The arsenic concentrations in the kidney and liver tissues were found significantly reduced with all the flavonoids co-treatment (p < 0.001). There was a reduction in the levels of superoxide dismutase (SOD), reduced glutathione (GSH), and glutathione S-transferase (GST) antioxidant markers, with the increased lipid peroxidation (LPO), protein carbonyl content (PCC), and catalase (CAT) levels in the arsenic-intoxicated mice performed in the different tissues. The biochemical homeostasis alterations were well correlated with the estimations of cholinesterase enzyme levels in the brain tissues (p < 0.05) along with DNA damage analysis (Comet) carried out in the blood cells (p < 0.05). These above results are well corroborated with the histopathological findings performed in the brain tissue, along with the increased upregulation seen in the Nrf2 signalling, with all the flavonoid co-treatment carried in the kidney tissue. The administration of BCA, phloretin, and EGCG, in a major way, reversed the alterations in the abovementioned parameters in the arsenic-intoxicated mice. Our findings revealed the beneficial effects of the flavonoids against the arsenic-induced toxicity, due to their ability to enhance the intracellular antioxidant response system by modulating the Nrf2 signaling pathway.

Electropositive Nanodiamond-Coated Quartz Microfiber Membranes for Virus and Dye Filtration

Electropositive membranes demonstrating high flux at low pressure differentials show great promise as universal separation platforms for viruses and other charged entities when centralized systems of water and power are scarce. However, the fabrication of a suitably stable membrane with optimal electrostatic characteristics remains a challenge. Here, hydrogenated detonation nanodiamond was loaded onto a quartz microfiber support membrane and coupled to the membrane surface under a high vacuum annealing process. The fabricated membranes display a zeta potential of +45 mV at pH 7 and an isoelectric point around pH 11. We show that the nanodiamond coating is robust to prolonged periods of pressurized water flow by performing extensive zeta potential measurements over time, and water filtration tests demonstrated excellent membrane retention for the electronegative dye molecule acid black 2, and at least a 6.2 log10 reduction in MS2 bacteriophage from feed waters (>99.9999%).

Preparation of GO/Fe3O4@PMDA/AuNPs nanocomposite for simultaneous determination of As3+ and Cu2+ by stripping voltammetry

One of the critical challenges in the simultaneous determination of As³⁺ and Cu²⁺ by stripping voltammetry is the overlapping of their oxidation peaks. Therefore, the engineering of nanostructured sensors in order to uplift their electrochemical performance is a significant issue for the codetection of As³⁺ and Cu²⁺. Herein, we modified a glassy carbon electrode with a new nanocomposite based on poly methyldopa along with gold nanoparticles immobilized on the surface of magnetic graphene oxide (GCE/GO/Fe₃O₄@PMDA/AuNPs) that can determine As³⁺ and Cu²⁺ with great sensitivity. Optimization of the measurement conditions by square wave stripping voltammetry (SWSV) caused the oxidation peaks of As³⁺ and Cu²⁺ to be distinguished significantly from each other, while the peak currents of As³⁺ and Cu²⁺ increased 9-12 fold, respectively, compared to the bare electrode. The proposed electrode exhibits low detection limits (S/N ≥ 3): 0.15 ppb for As³⁺ and 0.11 ppb for Cu²⁺. The GCE/GO/Fe₃O₄@PMDA/AuNPs also has good linearity over a wide concentration range from 5 to 500 ppb for As³⁺ and 0.5-750 ppb for Cu²⁺. The good recovery values were obtained for the analysis of As³⁺ and Cu²⁺ in pool and drinking water samples.

Recent development of chromogenic and fluorogenic chemosensors for the detection of arsenic species: Environmental and biological applications

Due to biological and environmental significance of highly toxic arsenic species, the design, synthesis and development of chemosensors for arsenic species has been a very active research field in recent times. In this review, we summarize recent works on the sensing mechanisms employed by fluorometric/colorimetric chemosensors and their applications in arsenic detection. Various types of sensing strategies can be categorized into six types including (i) chemosensors based on hydrogen bonding interactions; (ii) aggregation induced emission (AIE) based chemosensors; (iii) chemodosimetric approach (reaction-based chemosensors); (iv) metal coordination-based sensing strategy; (v) chemosensors based on metal complex displacement approach and (vi) metal complex as chemosensor. All these sensing strategies are very much simple and sensitive for use in the design of arsenic selective chromogenic and fluorogenic probes.

Fluoride and arsenic contamination in drinking water due to mining activities and its impact on local area population

Contamination of arsenic and fluoride in drinking water reservoirs is a serious health issue in the Sibi district, Balochistan, Pakistan. The contamination has already been affecting a large population of the district. Dental fluorosis and dermatitis are the most common reported illnesses in the area. This study focused on the evaluation of the root causes and pathway by which it reached to the body. Questioner analysis, simple examination, and pictorial representation were used to study the prevalence of diseases caused by As and F. People of the Sibi district were found to consume both surface and groundwater, which were highly contaminated with arsenic and fluoride. The saturation index, ranging from 1 to 7, showed high enrichment of contaminants in both types of water. Geochemical calculations and the sodium absorption ratio were evaluated. High values of the saturation index of different salts showed high saturation of salts in water. The principal component analysis grouped the data into three clusters, showing that the surface water has no resemblance with the control water. High degree of contamination was observed for most of the samples, whereas, some samples of ground water were closed to the control group; a group of samples within WHO limits. The correlation studies and other calculations also revealed that the F and As reached lethal limits in the drinking water and thus caused severe health damage to the local area population. The diseases found in the area are fluorosis, keratosis, dermatitis, and melanosis.

Field demonstration of solar-powered electrocoagulation water treatment system for purifying groundwater contaminated by both total coliforms and arsenic

People who drink groundwater in rural areas of Southeast Asia are exposed to pathogens and arsenic (As)-related health problems. A water treatment system consisting of electrocoagulation reactors, using iron (Fe) electrodes and a filtration tank, was designed to treat complex contaminated groundwater for drinking. Its applicability was demonstrated near the Red River in Vietnam. The water treatment system reduced 10.3 CFU/mL of total coliform and 376 μg/L of As(III) in the groundwater to 0 CFU/mL and 6.68 μg/L, respectively. Total coliforms were attenuated by Fe(II) infiltration or enmeshed during Fe precipitate formation. Of the total As, 43% formed As(III) complexation with the Fe precipitates and the other 57% was oxidized to As(V) then adsorbed to Fe precipitates. The Fe precipitates, containing total coliforms and As, were separated from the discharge water in the filtration tank. The system required 49 W of power to operate, which equates to 423 kWh/year, to continuously purify 0.5 t water/day. This requirement was powered by a 380-750 W solar panel, without external energy supply, making the water treatment system an appropriate option for addressing drinking water problems in rural areas.

Influence of basin-wide geomorphology on arsenic distribution in Nadia district

The present study depicts the geospatial relation between basinal geomorphology and heterogeneous arsenic (As) distribution in the Bengal Delta Plain (BDP). The distribution pattern largely varies throughout the study area (higher: Karimpur-II As_T average 214.73 μgL^-1; lower: Tehatta As_T average 27.84 μgL^-1). Both safe (low As) and unsafe (high As) areas are identified within the single shallow aquifer (<50 m), where they are in close vicinity. Statistical analysis shows that Padma river basin is the most contaminated (As_T avg. 214.7 ± 160 μgL^-1) and Churni-Ichhamati river basin (As_T avg. 108.54 ± 89.43 μgL^-1) is the least contaminated with groundwater As. Moreover, the role of geomorphological features influencing the geospatial distribution of As has been studied and meandering features are found to correlate with high As wells (r² = 0.52), whereas, natural levees are correlated with safer wells (r² = 0.57). In the meandering features, the deposition of sedimentary organic matter (SOM) facilitates the reduction of As bearing Fe(III) oxy-hydroxides and subsequent higher As mobilization. In natural levees, surface derived labile organic matter (DOC and FOM, Fresh Organic Matter) from different land-use patterns (Habitation, degraded waterbodies, cattle dwelling, sanitation, etc.) is transported to shallow aquifers (notably protein rich leakage sewage). The fresh organic carbon transported to the shallow aquifers, thereby triggering As release by microbe-mediated reductive dissolution of hydrated Fe(III)-oxides (HFO). Iron reduction (mostly amorphous) is playing an important role in the release of As depending on basin-wise sedimentation pattern, local recharge, accumulation of silt/clay/micas at the top with corresponding reactive oxidation of organic carbon. These are important components and often helping the cyclic water-rock interaction of As causing such heterogeneous geospatial distribution. The delineation of aquifer with regard to safer and unsafe areas would immensely help to supply safe drinking water to the rural community.

Effects of organic selenium on absorption and bioaccessibility of arsenic in radish under arsenic stress

Arsenic (As) exposure poses a serious threat to human health. The present study investigated the effects of organic Se on As accumulation, migration, and As bioaccessibility in As-stressed radish. The results showed that organic Se can effectively block the accumulation of As in radish, reduce As bioaccessibility, and promote the conversion of As from inorganic to organic form. The total As content decreased with increasing Se application in raw radish roots, the gastric fraction and the gastrointestinal fraction. Compared to the control (CK) group, the As bioaccessibility in the 24Se treatment of the yeast Se and malt Se groups decreased by 26% and 37%, respectively. These findings provide new comprehensive information for the application of organic Se to alleviate the toxicological effects of As and reduce the health risks of As in edible plants. In the future, it is necessary to carry out a deeper study of the interaction between Se and As through advanced analytical methods.

Arsenic Exposure and Incident Hypertension of Adult Residents Living in Rural Areas Along the Yangtze River, Anhui, China

OBJECTIVE

As a widespread toxic metal, arsenic had potential effect for hypertensive. We evaluated the association between urinary arsenic and the incidence of hypertension in adult residents along the Yangtze River of China.

METHODS

We conducted the study of 1358 adults 18 to 74 years of age from Chizhou, Maanshan, and Tongling of Anhui province, who participated in the baseline study in 2014 to 2015. Inductively coupled plasma optical emission spectrometry was used to measure urinary as of residents, and follow-up extended through 2016 to 2017.

RESULTS

We identified 275 hypertension events. The hazard ratios (HRs) of highest quartile arsenic compared with lowest quartile was 1.49 for hypertension events (95% confidence interval [CI] = 1.05 to 2.12), and HRs (≥P20 vs <P20) was 1.37 (95% CI = 1.02 to 1.84).

CONCLUSIONS

Higher level of arsenic exposure might play a role in increasing the incidence of hypertension.

Elemental concentration and migratability in bioplastics derived from organic waste

In line with the Circular Economy approach, the production of polyhydroxyalkanoate (PHA) with organic waste as the feedstock may a biotechnological application to reduce waste and recover high-value materials. The potential contaminants that could transfer from bio-waste to a PHA include inorganic elements, such as heavy metals. Hence, the total content and migratability of certain elements were evaluated in several PHA samples produced from different origins and following different methods. The total content of certain elements in PHA ranged between 0.0001 (Be) and 49,500 mg kg^-1 (Na). The concentrations of some alkaline (Na and K) and alkaline earth (Ca and Mg) metals were highest, which are of little environmental concern. The feedstock type and PHA stabilisation and extraction procedures affected the element contents. Several sets of experiments were conducted to evaluate the migration of elements from the PHA samples under different storage times, temperatures, and pH levels. The total contents of some heavy metals (As, Cd, Fe, Hg, Ni, Pb, and Zn) in PHA produced from fruit waste or crops (commercial PHA) were lower than those in the PHA samples produced from the mixture of the organic fraction of municipal waste and sludge from wastewater treatment. Both the PHA obtained by extraction from wet biomass (acid storage) with aqueous phase extraction reagents and commercial PHA were below the migration limits stipulated by the current Toy Safety Directive and by Commission Regulation (EU) October 2011 on plastic materials and articles intended to come into contact with food under frozen and refrigerated conditions.

Long-term observational study on 6223 survivors of arsenic poisoning due to contaminated milk powder during infancy

In 1955, an outbreak of arsenic poisoning caused by the ingestion of arsenic‐contaminated Morinaga Dry Milk occurred in western Japan. This study aimed to assess the mortality and cancer incidence risk among Japanese individuals who were poisoned during this time as infants. In total, 6223 survivors (mean age at enrollment, 27.5 y) who had ingested contaminated milk when they were aged ≤ 2 y participated in this study. Follow‐up was conducted from 1982 to 2018 (mean follow‐up duration, 30.3 y). Standardized mortality ratio (SMR) and standardized incidence ratio (SIR) were used to compare mortality and cancer incidence rates of subjects with the respective Japanese population rates, and 95% confidence intervals (95% CIs) of the SMR and SIR were also calculated. In total, 561 deaths and 524 new cancer cases were observed. A statistically significant increase in mortality rate was observed for all causes (SMR, 1.15; 1.01‐1.19), nervous system disease (2.83, 1.62‐4.19), respiratory disease (2.02, 1.37‐2.62), genitourinary system disease (2.25, 1.10‐3.73), and traffic accident (2.03, 1.14‐3.04). In contrast, a significant decrease in cancer incidence rate was observed for all cancers (SIR, 0.96; 0.84‐0.99), stomach cancer (0.77, 0.57‐0.92), colon cancer (0.63, 0.41‐0.85), rectum cancer (0.69, 0.43‐0.95), and breast cancer (0.72, 0.52‐0.89). Liver cancer showed a high mortality rate (SMR, 1.68; 1.06‐2.31). In this study, after the long‐term follow‐up we revealed overall and cause‐specific mortality and cancer incidence risk among survivors who ingested arsenic‐contaminated dry milk as infants.

Density Functional Theory Investigation of As(III) S-Adenosylmethionine Methyltransferase

Arsenic is one of the most pervasive environmental toxins. It enters our water and food supply through many different routes, including the burning of fossil fuels, the application of arsenic-based herbicides, and natural sources. Using a density functional theory (DFT) cluster approach, the mechanism of arsenic (III) S-adenosylmethionine methyltransferases and various selenium-containing analogues was investigated. Notably, the methylation of arsenic by arsenic (III) S-adenosylmethionine is proposed to be a way to remove arsenic from contaminated water or soil. From the DFT cluster results, it was found that the selective substitution of the active-site Cys44, Cys72, and Cys174 residues with selenocysteines had a marginal effect on the barrier for CH₃ transfer. Specifically, the average Gibbs activation energy was calculated to be only 4.2 kJ mol^-1 lower than the Gibbs activation energy of 107.4 kJ mol^-1 for the WT enzyme. However, importantly, it was found that with selective mutation, the methylation process becomes considerably more exergonic, where the methylation reaction can be made to be 26.4 kJ mol^-1 more exergonic than the reaction catalyzed by the WT enzyme. Therefore, we propose that the selective substitution of the active-site Cys44, Cys72 and Cys174 residues with selenocysteines could make the process of methylation and volatilization more advantageous for bioremediation.

Association of arsenic with recurrence of urinary bladder cancer

Arsenic is known to be an important aetiological factor for the development of urinary bladder cancer. It is known to be found excessively in ground water in certain geographical areas, including West Bengal. We have studied patients with recurrent bladder cancer from different areas of this Indian state and correlated arsenic as a causative aetiological factor for development and aggressiveness of the biological behaviour of urinary cancer. We included 31 patients from various parts of West Bengal state with recurrent bladder cancer who were operated in our institute. Their clinical and residential data and their arsenic content of tumour tissue were measured. Statistical analysis was performed to test the association of tissue arsenic with clinicopathological features of recurrent disease. We found very high levels of arsenic in tumour tissue in all residents of the districts with high prevalence of arsenic in the drinking water. We also observed more aggressive clinicopathological progression and early recurrence in patients with high arsenic content. We conclude that arsenic is a causal factor in the clinicopathological progression of recurrent urinary bladder cancer. Measures to decrease the level of arsenic in drinking water should be taken as this may both improve clinicopathological outcomes in the recurrence of urinary bladder carcinoma, as well as reducing its overall incidence.