Arsenic contamination of groundwater and its induced health effects in Shahpur block, Bhojpur district, Bihar state, India: risk evaluation

Environmental contamination of arsenic: pathway analysis through water-soil-feed-livestock in Nadia District (India) and potential human health risk

This study investigated arsenic (As) concentrations in diverse environmental components and their potential impact on the health risks faced by residents of the arsenic (As)-contaminated Nadia district in West Bengal, India. A random selection of 182 cattle and 255 goats from 40 livestock farmers in the district revealed that both animals and humans were naturally exposed to elevated arsenic levels through contaminated drinking water, foods, grasses, concentrate feeds, various fodder tree leaves, and other food/feed resources. The mean As concentration in roughages (483.18 µg/kg DM) was significantly higher (p < 0.001) than in tree leaves (391.53 µg/kg DM), and concentrate feed/ingredients (186.66 µg/kg DM). Pond water exhibited higher arsenic levels (106.11 µg/L) compared to shallow tube well water (47.96 µg/L) and deep tube well water/tap water (10.64 µg/L and 10.04 µg/L, respectively). The mean arsenic concentration in soils DM of fodder fields, crop fields, and grassland was 10.25, 10.58, and 10.20 mg/kg, respectively. It was observed that protein-rich feeds had lower levels of arsenic accumulation (p < 0.048), while fiber-rich feeds containing more cellulose, hemicellulose, and lignin had higher arsenic levels (p < 0.017). Goats consumed 73.46% more arsenic per kg body weight compared to dairy cows. Although chronic and sub-chronic arsenic exposure in the district did not typically manifest symptoms or visible signs in ruminant animals, concentrations in the hair and feces of both cattle and goats exceeded normal values. Cattle feces had significantly higher arsenic (410.43 µg/kg DM) levels (p < 0.001) than goat feces (227.00 µg/kg DM), and arsenic concentration in cattle hair (1917.74 µg/kg DM) was also significantly greater (p < 0.001) than goat hair (1435.74 µg/kg DM). Arsenic levels in milk samples from both species were below 10 µg/kg. Liver (356.02 µg/kg DM) and kidney (317.22 µg/kg DM) contained significantly higher (p < 0.001) levels of arsenic compared to muscle (204.23 µg/kg DM), and bone (161.98 µg/kg DM) in local meat-type adult male goats. The skin accumulated the highest amount of arsenic (576.24 µg/kg DM) among the non-edible parts of the goat carcass. The cumulative cancer risk value for adults was 4.96 × 10-3, exceeding the threshold value (1 × 10-6). This suggests a significant risk of cancer development for the population in arsenic-affected areas. Non-cancer risks (hazard indexes) were estimated at 11.01 for adults. Our observations revealed that the highest bioaccumulation of arsenic occurred in the hair of cows, and goats in the examined localities. The biotransformation factor (BTF) for hair was much higher compared to other excreted samples from both species. The calculated BTF followed the order: hair > feces > milk for cows and goats. Livestock farmers in Nadia district are advised to carefully select feed resources, prioritizing those high in crude protein and low in neutral detergent fiber, and they should provide drinking water from deep aquifers to ensure the safety of milk and meat for human consumption.

An evaluation of arsenic contamination status and its potential health risk assessment in villages of Nadia and North 24 Parganas, West Bengal, India

The present study was conducted to evaluate the arsenic (As) contamination and possible associated health hazards to exposed population in four villages of two districts (Nadia and North 24 Parganas) of West Bengal, India. The study included two villages each from Nadia (Jaguli and Kugacchi) and North 24 Parganas (Chamta and Byaspur) districts. Groundwater, surface water, soil, rice grains and rice-based food samples were collected from these villages. The results revealed the presence of As in high concentrations in groundwater (35.00 to 186.00 µg L-1), surface water (30.00 to 61.00 µg L-1), soil (46.17 to 66.00 mg kg-1), rice grains (0.017 to 1.27 µg g-1) and rice-based food products (0.012 to 0.40 µg g-1). The maximum As levels were recorded in all types of samples collected from Kugacchi village. The rice grain samples included high-yielding and local varieties, and the level of As in high-yielding varieties was found to be higher (0.72 to 1.27 µg g-1) than in local varieties (0.25 to 1.06 µg g-1). The data of As concentrations was used for understanding the hazard quotient (HQ) and incremental lifetime cancer risk (ILCR) to the As-exposed population, and significant non-carcinogenic and carcinogenic risks were revealed considering consumption of rice grains at 400 g per day. The study demonstrates the severity of As contamination in the surveyed villages, which may pose a hindrance to attainment of sustainable development goals (SDGs) by 2030 and proposes the implementation of requisite safety measures.

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.

Assessing the health risks of coal-burning arsenic-induced skin damage: A 22-year follow-up study in Guizhou, China

Risk assessment of arsenic-induced skin damage has always received significant global attention. Theories derived from arsenic exposure in drinking water may not be applicable to the coal-burning type to arsenic-exposed area. Furthermore, very few studies have successfully determined the reference value of cumulative arsenic (CA) exposure that leads to specific skin lesions. In this study, we conducted a 22-year follow-up investigation to assess the risk of skin lesions and cancer resulting from long-term, multi-channel arsenic exposure from hazard identification, dose-response assessment, exposure assessment, and risk characterization. The results show that the arsenic exposure can significantly increase the prevalence of skin lesions. For each interquartile range increase of hair arsenic (HA) and CA, the risk of skin damage increased by 1.91 and 3.90 times, respectively. The lower confidence limit of the benchmark dose of HA of arsenic-induced various skin lesions ranged from 0.07 to 0.12 μg·g-1, and 932.57 to 1368.92 mg for CA. The chronic daily intake, lifetime average daily dose in the arsenic-exposed area after the comprehensive prevention and control measures have decreased significantly, but remained higher than the daily baseline level of 3.0 μg·kg-1·d-1. Even as recently as 2020, the hazard quotients and hazard index still exceeded 1, measuring 155.33 and 55.20, and the lifetime excess risk of skin cancer (2.80 × 10-3) remains significantly higher than the acceptable level of 10-6. Our study underscores the effectiveness of comprehensive prevention and control measures in managing high arsenic exposure in coal-burning arsenic poisoning areas. However, it is crucial to acknowledge that the risk of both non-carcinogenic and carcinogenic effects on the skin remains substantially higher than the acceptable level. We recommend setting reference limits for monitoring skin damage among individuals exposed to arsenic, with a recommended upper limit of 0.07 μg·g-1 for HA and a maximum acceptable level of 935.57 mg for CA.

Fluorescence 'Turn-on' Dual Sensor for Selective Detection of Cd2+ and H2AsO4- in Water

A multi responsive fluorescent probe, N',2-bis(E-4-(diethylamino)-2-hydroxybenzylidene)hydrazine-1-carbothiohydrazideV(H₂L) has been synthesized through one step condensation method. Probe, H₂L shows 'turn-on' dual sensing properties towards Cd²⁺ and H₂AsO₄^- at two distinct wavelength. The probe (H₂L) is spectroscopically characterized and the chemo-sensing mechanism has been demonstrated through ¹H NMR, absorption, steady state and time resolved emission study. The most promising advantage of the probe is its application in the one-pot detection of Cd²⁺ (λ_em = 462 nm) and H₂AsO₄^-(λ_em = 492 nm) where intense emission appears at two different wavelengths and the observed limit of detection (LOD) of H₂L towards Cd²⁺ and H₂AsO₄^- are 2.67 × 10^-8 M and 5.14 × 10^-6 M respectively. Further the 'turn-on' emission property of H₂L towards Cd²⁺ is applied to construct INHIBIT logic gate.

Appraisal of groundwater arsenic on opposite banks of River Ganges, West Bengal, India, and quantification of cancer risk using Monte Carlo simulations

This study was conducted to inspect the spatial distribution, source identification, and risk assessment of groundwater arsenic (As) in different blocks that lie on the opposite banks of river Bhagirathi (a distributary of river Ganges), Murshidabad, West Bengal, India. It has been observed that the blocks that lie towards the eastern bank of river Bhagirathi have elevated arsenic and comparatively more reducing groundwater (lower oxidation-reduction potential and high iron). About 66% of groundwater samples across the district have arsenic concentration higher than the World Health Organization (WHO) permissible limit. Speciation of groundwater arsenic reveals that about 90% of arsenic species were present as arsenic (III). Further, principal component analysis (PCA) was employed to identify the controlling factors that favor the release of arsenic. PC1 comprises EC, TDS, As, Fe, TOC, and HCO₃^- with moderate loadings, which suggests microbially mediated degradation of organic matter (OM), helps in reductive dissolution of arsenic-bearing Fe-Mn oxyhydroxides. Results pointed out severe groundwater arsenic poisoning; hence, a health risk assessment was performed for the exposure of arsenic in groundwater, using incremental lifetime cancer risk (ILCR) models coupled with Monte Carlo simulations. On the eastern bank of river Bhagirathi, incremental lifetime cancer risk (ILCR) due to oral exposure (5th to 95th percentile values) ranged from 1.30538E - 04 to 9.31398E - 03 with a mean of 2.84194E - 03 for adults, which is 2841 times higher than the USEPA high safety risk guidelines of one in 1 million. The outcomes of the results will be useful for the policymakers and regulatory boards in defining the actual impact and deciding the pre-remediation goals.

Drinking water and the implications for gender equity and empowerment: A systematic review of qualitative and quantitative evidence

BACKGROUND

Safe drinking water is a fundamental human right, yet more than 785 million people do not have access to it. The burden of water management disproportionately falls on women and young girls, and they suffer the health, psychosocial, political, educational, and economic effects. While water conditions and disease outcomes have been widely studied, few studies have summarized the research on drinking water and implications for gender equity and empowerment (GEE).

METHODS

A systematic review of primary literature published between 1980 and 2019 was conducted on drinking water exposures and management and the implications for GEE. Ten databases were utilized (EMBASE, PubMed, Web of Science, Cochrane, ProQuest, Campbell, the British Library for Development Studies, SSRN, 3ie International Initiative for Impact Evaluation, and clinicaltrials.gov). Drinking water studies with an all-female cohort or disaggregated findings according to gender were included.

RESULTS

A total of 1280 studies were included. GEE outcomes were summarized in five areas: health, psychosocial stress, political power and decision-making, social-educational conditions, and economic and time-use conditions. Water quality exposures and implications for women's health dominated the literature reviewed. Women experienced higher rates of bladder cancer when exposed to arsenic, trihalomethanes, and chlorine in drinking water and higher rates of breast cancer due to arsenic, trichloroethylene, and disinfection byproducts in drinking water, compared to men. Women that were exposed to arsenic experienced higher incidence rates of anemia and adverse pregnancy outcomes compared to those that were not exposed. Water-related skin diseases were associated with increased levels of psychosocial stress and social ostracization among women. Women had fewer decision-making responsibilities, economic independence, and employment opportunities around water compared to men.

CONCLUSION

This systematic review confirms the interconnected nature of gender and WaSH outcomes. With growing attention directed towards gender equity and empowerment within WaSH, this analysis provides key insights to inform future research and policy.

Protective efficacy of Coriandrum sativum seeds against arsenic induced toxicity in Swiss albino mice

Arsenic poisoning in ground water is one of the most sensitive environmental pollutant causing serious pollution all over the world. Chronic arsenic exposure through drinking water to humans leads to major public health related issues. There have been very meagre studies which reported that, the plant constituents proved to exhibit protective effect from arsenicosis. Therefore, the present study aims to evaluate the protective efficacy of Coriandrum sativum seeds extract against sodium arsenite induced toxicity in Swiss albino mice. In the present study twenty-four male healthy Swiss albino mice (30 ± 5 g) were divided into four groups (n = 6), where the control group received normal diet and water; group II and group III treated with sodium arsenite (2 mg per kg body weight per day) for 2 and 4 weeks respectively. The group IV mice were administered with C.sativum seeds extract at the dose of 150 mg per kg body weight per day for 4 weeks upon sodium arsenite pretreated (2 mg/kg body weight for 4 weeks per day) mice. After the complete dose duration, all the treatment group animals were sacrificed same day for haematological, biochemical and histopathological study. In the arsenic treated mice, there were significant (p < 0.0001) changes in the serum levels of ALT, AST, ALP, urea, uric acid and creatinine as well as in the haematological parameters. In contrast, after the administration with C.sativum seeds extract upon arsenic pretreated mice, there was significant (p < 0.0001) improvement observed in the hepatic and renal biomarker parameters as well as haematological variables. In the arsenic intoxicated mice,  after administration with C.sativum seeds extract there was significant (p < 0.0001) reduction in the arsenic concentration in blood, liver and kidney tissues as well as in the serum LPO levels. Furthermore, the histopathological study showed that, C.sativum seeds extract administrated group of mice significantly restored the liver and kidney at cellular level against arsenic induced toxicity. The entire study concludes that C.sativum seeds extract possesses the ameliorative effect against arsenic induced liver and kidney intoxication.

Arsenic contamination, induced symptoms, and health risk assessment in groundwater of Lahore, Pakistan

The purpose of this study is to evaluate the arsenic concentration and related health risks in groundwater extracted from tube wells. The physicochemical parameters, including arsenic (As), were investigated using standard procedures. The parameters were found within the permissible limits except for arsenic, which was 78 µg/L. Unfortunately, 82% of the collected water samples were found contaminated with arsenic and exceeded the permissible limit set by the world health organization (10 µg/L). The water intake and its relationship between arsenic concentration, time, and induced symptoms in the study area residents were observed. Skin pigmentation, skin irritation, and numbness of the body were recognized as the major symptoms, and these symptoms were significantly correlated with p-value ˂ 0.05. In comparison, individuals who intake As-contaminated water (> 50 µg/L) for a duration of > 20 years show severe symptoms. Furthermore, health risk assessment associated with arsenic in terms of chronic daily intake (CRI), hazard quotient (HQ), and cancer risk assessment probability (CR) in groundwater was also studied. The HQ of arsenic was 7.46, and the CR value of As on Ravi road was as high as 0.00149, which indicates a possibility of cancer risk in the community Ravi road, Lahore. Based on the findings, the study area needs special monitoring and management of groundwater to reduce health risks associated with contaminated drinking water. Moreover, suitable remediation methods for removing arsenic should be adopted to avoid arsenic exposure and related health risks.

Application of fingernail samples as a biomarker for human exposure to arsenic-contaminated drinking waters

This study evaluated the relationship between arsenic uptake via drinking water ingestion and arsenic concentration in fingernails as a biomarker for human exposure. For this purpose, we collected fingernail samples from 40 healthy participants of arsenic-affected rural regions of Kaboudrahang County, the west of Iran. A total of 49 fingernail samples were also collected from individuals who lived in areas where contamination of drinking water sources with arsenic had not been reported. It was found that the fingernails arsenic contents in 50 and 4.08% of the samples collected from arsenic-contaminated and reference villages were higher than the normal arsenic values of nails (0.43-1.08 µg/g), respectively. Based on the results of adjusted multiple linear regression, a significant association was found between groundwater and fingernails arsenic concentration (p < 0.001). Moreover, a statistically significant association was shown between arsenic in the fingernail samples and gender (p = 0.037). Fingernails arsenic contents were not significantly affected by other variables including age, smoking habits, and BMI (p > 0.05). In light of the results of this study, the use of biological indicators such as fingernail tissues due to easier sampling and less risk of external contamination is suitable for assessing exposure to heavy metals in contaminated areas.

Predicting sustainable arsenic mitigation using machine learning techniques

This study evaluates state-of-the-art machine learning models in predicting the most sustainable arsenic mitigation preference. A Gaussian distribution-based Naïve Bayes (NB) classifier scored the highest Area Under the Curve (AUC) of the Receiver Operating Characteristic curve (0.82), followed by Nu Support Vector Classification (0.80), and K-Neighbors (0.79). Ensemble classifiers scored higher than 70% AUC, with Random Forest being the top performer (0.77), and Decision Tree model ranked fourth with an AUC of 0.77. The multilayer perceptron model also achieved high performance (AUC=0.75). Most linear classifiers underperformed, with the Ridge classifier at the top (AUC=0.73) and perceptron at the bottom (AUC=0.57). A Bernoulli distribution-based Naïve Bayes classifier was the poorest model (AUC=0.50). The Gaussian NB was also the most robust ML model with the slightest variation of Kappa score on training (0.58) and test data (0.64). The results suggest that nonlinear or ensemble classifiers could more accurately understand the complex relationships of socio-environmental data and help develop accurate and robust prediction models of sustainable arsenic mitigation. Furthermore, Gaussian NB is the best option when data is scarce.

Arsenic and Human Health: Genotoxicity, Epigenomic Effects, and Cancer Signaling

Arsenic is a well-known element because of its toxicity. Humans as well as plants and animals are negatively affected by its exposure. Some countries suffer from high levels of arsenic in their tap water and soils, which is considered a primary arsenic-linked risk factor for living beings. Humans generally get exposed to arsenic by contaminated drinking waters, resulting in many health problems, ranging from cancer to skin diseases. On the other hand, the FDA-certified drug arsenic trioxide provides solutions for various diseases, including several types of cancers. This issue emphasizes the importance of speciation of the metalloid elements in terms of impacts on health. When species get exposed to arsenic, it affects the cells altering their involvement. It can lead to abnormalities in inflammatory mechanisms and the immune system which contribute to the negative impacts generated on the body. The poisoning originating from arsenic gives rise to various biological signs on the body which can be useful for the diagnosis. It is important to find true biomarkers for the detection of arsenic poisoning. In view of its application in medicine and biology, studies on understanding the biological activity of arsenic have increased. In this review, we aim at summarizing the current state of knowledge of arsenic and the mechanism behind its toxicity including genotoxicity, oxidative insults, epigenomic changes, and alterations in cellular signaling.

Detailed Analysis of Neurological Symptoms and Sensory Disturbances Due to Chronic Arsenic Exposure in Toroku, Japan

As a result of population growth and the development of tube wells, humans’ exposure to arsenic has increased over the past few decades. The natural course of organ damage secondary to arsenic exposure is not yet well understood. In Toroku, Japan, an arsenic mine was intermittently operated from 1920 to 1962, and residents were exposed to high concentrations of arsenic. In this paper, we analyzed 190 consecutive residents for whom detailed records of neurological symptoms and findings were obtained from 1974 to 2005. All participants were interviewed regarding the presence of general, skin, hearing, respiratory, and neurological symptoms. Neurological symptoms were classified into extremity numbness or pain, constipation, dyshidrosis, sensory loss, and muscle atrophy. Superficial and vibratory sensation was also evaluated. More than 80% of participants experienced extremity numbness, and numbness was the most common neurological symptom. Numbness was associated with superficial sensory disturbance, and was correlated with the subsequent development of other neurological symptoms, including autonomic and motor symptoms. No previous studies have investigated the natural course of chronic arsenic intoxication; thus, these data serve as a guide for detecting early symptoms due to arsenic exposure.

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.

Identification of processes mobilizing organic molecules and arsenic in geothermal confined groundwater from Pliocene aquifers

Organic matter (OM) has been accepted as an important trigger fueling Fe(III) oxide reduction and arsenic release in the late Pleistocene-Holocene anoxic aquifers, whereas its fates and roles on arsenic mobility in the Pliocene aquifer are unclear. To fill this gap, groundwaters from a confined Pliocene aquifer (CG) and an unconfined Holocene aquifer (UG) were sampled in the Guide Basin, China, to monitor evolutions of groundwater geochemistry and OM molecular signatures along the groundwater flow path. The outcomes showed that groundwater pH, temperature, and arsenic concentrations in the CG samples generally increased along the groundwater flow path, which were much higher than those in the UG samples. The numbers and intensities of recalcitrant molecules (polycyclic aromatics and polyphenols) in the CG samples remarkably increased along the path, but relatively labile molecules (highly unsaturated and phenolic compounds and aliphatic compounds) showed the opposite trends. The arsenic-poor (<10 μg/L) UG samples contained more labile molecules than the arsenic-rich CG samples. High groundwater pH, temperature, and sediment age in the confined aquifers may be responsible for the selective mobilization of the unique polycyclic aromatics and polyphenols. The mobilized recalcitrant organic molecules may enhance arsenic release via electron shuttling, complexation, and competition. Furthermore, high temperature and pH may also facilitate arsenic desorption. The study provides molecular-scale evidences that the mobilization of recalcitrant organic molecules and arsenic were concurrent in the geothermal confined groundwater.

The impact of chronic co-exposure to different heavy metals on small fibers of peripheral nerves. A study of metal industry workers

Background

Chronic exposure to heavy metals affects various organs, among them the brain and peripheral nerves. Polyneuropathy is mainly length-dependent with predominantly sensory symptoms. There have been few studies on small fiber neuropathy due to heavy metal intoxication.

Methods

We investigated 41 metal industry workers, mean age 51.3 ± 10.5 years, with at least 5 years’ professional exposure to heavy metals, and 36 age- and sex-matched healthy controls. We performed neurological examinations, and assessed blood levels of cadmium, lead, and zinc protoporphyrin, urine levels of arsenic, standard, sensory and motor electrophysiological tests in the ulnar and peroneal nerves, sympathetic skin responses from the palm and foot, and quantitative sensation testing from dermatomes C8 and S1.

Discussion

The results of standard conduction tests of all nerves significantly differed between groups. The latency of sympathetic skin responses achieved from the foot was also statistically significantly prolonged in the study group. Significant differences were seen in both C8 and S1 regions for temperature and pain thresholds, and for vibratory threshold only in the S1 region, while the dispersions of low and high temperatures were important exclusively in the C8 region.

Conclusions

We can conclude that co-exposure to many heavy metals results in explicit impairment of peripheral nerves. The lesion is more pronounced within small fibers and is predominantly connected with greater impairment of temperature-dependent pain thresholds. The evaluation of small fiber function should be considered in the early diagnosis of toxic polyneuropathy or in low-dose exposure to heavy metals.

Arsenic enrichment and its natural background in groundwater at the proximity of active floodplains of Ganga River, northern India

Arsenic contaminated groundwater is seen as one of the most critical routes of human exposure to geogenic pollutants. Recently around 40 million inhabitants of the world are living in the hazardous zone having groundwater As level >50 μg/L. As problem of groundwater in Bhagirathi-Ganga deltaic plain is well-known for over the last three decades. Hydrogeochemical analytical data related to the As concentration had been analysed to identify the As sources in groundwater of the active floodplains of the Ganga basin in Northern India. The natural background level of As was also estimated using Grubb's test and cumulative probability plots. The natural background level is a crucial parameter for identifying and quantifying groundwater pollution and assessing measures to control pollution. The anthropogenic addition of As in groundwater was separated by the estimated inflection point. The results show that the highest As concentration, which is 8-times more than the permissible limit, is observed at Gyantoli village in Begusarai district in Bihar state. Groundwater is alkaline with a high concentration of HCO₃^- as compared to other chemical parameters. Further, it indicates the dominance of carbonate weathering and relatively high pH values (range: 8.00-9.00) helps to release As in groundwater. The reducing environment of the aquifer system becomes oxic at the shallow depth due to comparatively shallow groundwater level, and impressive water level fluctuation resulting in vertical mixing of anthropogenic As contaminants.

Arsenic exposure from food exceeds that from drinking water in endemic area of Bihar, India

Extensive evidence of elevated arsenic (As) in the food-chain, mainly rice, wheat and vegetables exists. Nevertheless, the importance of exposure from food towards total As exposure and associated health risks in areas with natural occurring As in drinking water is still often neglected, and accordingly mitigations are largely focused on drinking water only. In this study, the contribution of food over drinking water to overall As exposure was estimated for As exposed populations in Bihar, India. Increased lifetime cancer risk was predicted using probabilistic methods with input parameters based on detailed dietary assessment and estimation of As in drinking water, cooked rice, wheat flour and potato collected from 91 households covering 19 villages. Median total exposure was 0.83 μg/kgBW/day (5th and 95th percentiles were 0.21 and 11.1 μg/kgBW/day) and contribution of food (median = 49%) to overall exposure was almost equal to that from drinking water (median = 51%). More importantly and contrary to previous studies, food was found to contribute more than drinking water to As exposure, even when drinking water As was above the WHO provisional guide value of 10 μg/L. Median and 95th percentile excess lifetime cancer risks from food intake were 1.89 × 10^-4 and 7.32 × 10^-4 respectively when drinking water As was below 10 μg/L and 4.00 × 10^-4 and 1.83 × 10^-3 respectively when drinking water As was above 10 μg/L. Our results emphasise the importance of food related exposure in As-endemic areas, and, perhaps surprisingly, particularly in areas with high As concentrations in drinking water - this being partly ascribed to increases in food As due to cooking in high As water. These findings are timely to stress the importance of removing As from the food chain and not just drinking water in endemic areas.

Comparative valuation of groundwater quality parameters in Bhojpur, Bihar for arsenic risk assessment

Arsenic endosmosis causes a severe threat to human health within the developing countries. This study assessed the levels of geogenic arsenic and other heavy metals affecting the release of As in the aquifers within the drinking water sources in Bhojpur district of Bihar, India. Eighteen water samples were collected in triplicates from hand-dug wells in six neighboring villages in proximity to the River Ganga namely Bakhorapur, Gaziapur, Parasrampur (or Kanhachhapara), Saraiya, Paiga and Gundiinin. The physicochemical parameters, ionic content and heavy metal analysis of the collected water samples indicated the region to be highly contaminated with arsenic, zinc, manganese and iron. The arsenic and iron concentration ranged between 24.3 and 168.07 μg/L and 0.17-1.16 mg/L respectively, indicating the excessive withdrawal of groundwater for domestic and irrigation purposes with a significant correlation between both the metals. Elevated concentration of zinc in the region attributed to the excessive application of chemical fertilizers and pesticides. Concentration of manganese was also in the higher range of 0.05-1.15 mg/L, primarily due to the urbanized industrial activities. Human health risk assessment within two population groups in the region indicated that the overall water quality is slightly contaminated but the risk associated with it is low. Water Quality Index ranged from 29 to 48, signifying the water quality to be poor. Residual sodium carbonate values indicated that few water sample sources are not suitable for irrigation purposes whereas, sodium adsorption ratio (SAR) values were within the acceptable limits to be used for irrigation.

Analysis of the qualitative evolution of groundwater in the Abouabou area in the Port-Bouët municipality (Abidjan, Côte d'Ivoire)

The study aimed to analyze the seasonal qualitative evolution of the Quaternary groundwater in the Abouabou area in order to see the capacity of this water to be used as a water supply by the populations. In-situ measurements (temperature, electrical conductivity, dissolved oxygen, turbidity and pH) and chemical parameter analyses (NH₄⁺, Ca²⁺, Mg²⁺, K⁺, Na⁺, NO₃^-, NO₂^-, PO₄^3-, SO₄^2-, Cl⁻ and HCO₃^-) were performed on the 24 samples collected during the four (4) seasons of the year. The use of Kruskal-Wallis and ANOVA tests has allowed the monitoring of seasonal variations in hydro-chemical parameters in well and borehole water. Also, the Piper diagram permit to identify the main hydrochemical facies according to the seasons. Finally, the Kohonen Self Organizing Maps (SOM) method was applied to physico-chemical parameters in order to highlight the spatial distribution of groundwater quality in the Abouabou area. The results show that, based on the physico-chemical parameters analysed, the groundwater is of good quality due to meeting WHO standards for drinking water consumption during all seasons of the year. Significant seasonal variations were recorded in the values of the parameters like turbidity, pH and Cl⁻ for well water and turbidity, PO₄^3-, NO₃^-, NH₄⁺, K⁺, Cl⁻ for borehole water. The hydrochemical facies shows a seasonal variation. Analysis of Abouabou's water reveals the variation of its hydrochemical facies. Thus, bicarbonate, calcium and magnesium facies during the long dry and rainy seasons move towards the chlorine, calcium and magnesium facies during the short dry and rainy seasons. Four water groups have been identified using SOM method, including heterogeneous groups composed mainly of borehole water (I and III) or of well water (II and IV). Borehole and well water acquire most of their mineralization by the infiltration of surface elements. Drinking water from boreholes is of good quality.

Remediation of carcinogenic arsenic by pyroaurite-based green adsorbent: isotherm, kinetic, mechanistic study, and applicability in real-life groundwater

The removal of the harmful carcinogen arsenic from drinking water by a green technology is a major concern in the field of environmental engineering. The sorptive profile of arsenic remediation by calcined Mg-Fe-layered double hydroxide, fabricated by a one-pot synthesis technique, was investigated to delineate its applicability in real-life water. The physicochemical properties of adsorbent, as demonstrated from spectroscopy and microscopy, which described the existence of amorphous material with significant surface roughness possess selectivity towards arsenic. The isotherm and kinetic along with thermodynamic modeling exhibited the occurrence of spontaneous (ΔG⁰ value = - 8.084 kJ/mol to - 10.942 kJ/mol), endothermic (ΔH⁰ value = 12.135 kJ/mol), and physisorption reactions (E_ad = 4.103-5.832 kJ/mol, E_a = 11.546 kJ/mol, S* = 0.0005 << 1, and ΔH_x = 9.23-16.29 kJ/mol) with high uptake rate and adsorption potential of adsorbent. The isotherm and kinetics were demonstrated by Temkin (R² = 0.944-0.969) and Elovich (R² = 0.996-0.998) models, respectively, with high statistical significance. The intraparticle diffusion model which established the rate-limiting step is the combination of both film and pore diffusions. The applicability of layered double hydroxide (LDH) material in the real-life water was confirmed by isotherm and kinetic modeling along with the regeneration/reuse potential. The adsorptive removal of arsenic by the LDH material exhibited to be a promising technique without creating any secondary hazard.

Groundwater Quality and Pollution Index for Heavy Metals in Saïs Plain, Morocco

BACKGROUND

Heavy metals contamination threatens groundwater resources in many areas around the world. Various methods to evaluate groundwater quality have been used to characterize sources of contamination and associated parameters. For assessment of heavy metals contamination, calculation of pollution indices is an effective tool for assessing water quality.

OBJECTIVES

The purpose of the present study was to assess heavy metal concentrations and determine distributions in Saïs plain, Morocco using multivariate analysis.

METHODS

A total of 144 groundwater samples were collected from twelve stations in Saïs from January 2018 to January 2019, and were analyzed for heavy metals (arsenic, cadmium, total chromium, lead, copper, iron, manganese and zinc) using atomic absorption spectrophotometry.

RESULTS

Chromium was found to be a major contaminant affecting water quality in Station 2 (0.057 mg/l) and Station 8 (0.065 mg/l), while elevated levels of iron were found in Station 7 (1.4 mg/l) and Station 11 (0.45 mg/l), and elevated levels of copper (2.9 mg/l) and zinc (3.39 mg/l) were found in Station 11, relative to other heavy metals. The high concentrations of these elements are related to anthropogenic pollutants. The factor analysis showed two components controlling groundwater chemistry. The results of the present study demonstrate that the concentrations of toxic metals, like Fe and Cr, are present in slight excess in one or two stations during one season. The calculated heavy metal pollution level for the groundwater of Saïs plain was below the index limit of 100.

CONCLUSIONS

The results show that groundwater is not polluted with respect to heavy metals and is acceptable for drinking. However, precautionary measures, such as managing the use of agricultural inputs and avoiding the use of wastewater in agriculture, are recommended in this area.

COMPETING INTERESTS

The authors declare no completing financial interests.

Valuing health damages due to groundwater arsenic contamination in Bihar, India

This paper estimates the health damages due to arsenicosis among people residing in two districts of Bihar, India. A primary survey of 388 households' comprises 3469 individuals from two arsenic-contaminated districts namely Patna and Bhojpur from Bihar was conducted to collect the data. Arsenic field test kits was used to test the arsenic level in drinking water of the sample households. The water test results indicate that 18.3% of the sample contained 50 ppb of arsenic, and 5.12% of the sample contained the arsenic between 300 and 500 ppb. Water source, doctor visits, work loss, and arsenic concentration levels are significant and positively related to arsenicosis, and awareness is significant but negatively related to arsenicosis. The incidence rate of arsenicosis was found to be more among females than males and children. Per-capita income, sanitation, awareness, and depth of water sources are significant and positively related to defensive activities, i.e., water purification. The annual wage loss, cost of treatment, and cost of illness for sample households are estimated as INR 2437.92 ($45.83), INR 5942.40 ($111.72) and INR 8380.32 ($157.55), respectively. The annual cost of illness for the society is estimated as INR 265.97 million ($5 million). Finally, the paper suggests policy implications of providing safe drinking water in the arsenic-affected areas in the State of Bihar, India, which can help reduce arsenicosis in sustainable manner, improve well-being and potential productivity.

Paternal exposure to arsenic resulted in oxidative stress, autophagy, and mitochondrial impairments in the HPG axis of pubertal male offspring

Despite the knowledge of AS-induced reprotoxicity, the literature concerning arsenic trioxide (As₂O₃)-induced oxidative stress and consequent intracellular events, like autophagy process, in the hypothalamic-pituitary- gonadal (HPG) axis of F1- pubertal male mice is sparse to date. Hence, we made an attempt to study the reproductive toxicities and the underlying mechanisms induced by As₂O₃ in the HPG axis of pubertal F1- male mice in correlation with oxidative stress-induced autophagy. Parental mice were challenged with As₂O₃ (0, 0.2, 2, and 20 ppm) from five weeks before mating, and continued till puberty age for the male pups. It was recorded that higher As₂O₃ doses (2 and 20 ppm) were a potent inducer of oxidative stress and autophagy in the HPG axis. Concomitant with a decrease on mean body weight, total antioxidant capacity, and stereology indices, an increase in the number of MDC-labeled autophagic vacuoles, and MDA/GSH ratio in HPG axis of pubertal F1- male mice which were exposed to higher As₂O₃ doses was observed. Meanwhile, concomitant with a dose-dependent increment in the gene expression of ATG3, ATG5, Beclin, as well as protein expression of P62, ATG12, and Beclin in HPG axis tissues; a dose-dependent decrease in PI3K and mTOR gene expression was recorded in the HPG tissues of pubertal F₁-males. Altogether, our observations suggest that higher doses of As₂O₃ have detrimental effects on the functionality of HPG axis in pubertal male mice offspring by increasing MDA/GSH ratio and autophagic cell death-related genes and proteins, as well as by reducing total antioxidant capacity.

Adsorption antagonism and synergy of arsenate(V) and cadmium(II) onto Fe-modified rice straw biochars

Arsenic-containing water poses a serious threat to human health. In this study, two types of Fe-modified rice straw biochars [(Fe-impregnated biochar (FeIm char) and pre-modified rice straw biochar (PMRS char)] were prepared, in which three ratios [1, 5, and 10% (w/w)] of Fe modification were evaluated, resulting in six different Fe-modified biochars. Then, a series of adsorption experiments, using single- and binary-metal solutions of As(V) and Cd(II), were conducted to investigate the performances of modified biochars on metal adsorption compared to pristine rice straw biochar (RS char). Results indicated Fe modification improved the As(V) adsorption capacity of biochar. PMRS char showed higher adsorption of As(V) than FeIm char. At the 5% Fe modification ratio (FMR), the As(V) removal by PMRS char (at 10 g/L dosage) from 100 mg/L As(V) solution was approximately 69.6%, which was higher than 46.1% of FeIm char or 22.6% of RS char. In contrast, the adsorption of Cd(II) was decreased after modified at 5 or 10% FMR. Interestingly, for treating solution containing As(V) and Cd(II) together, the adsorption of As(V) onto FeIm char or PMRS char prepared at 5 or 10% FMR remained higher than that onto RS char, while the simultaneous removal of Cd(II) ion by either modified biochar was kept over 50%. Thus, the finding of this study suggested Fe-modified biochars, especially prepared via the pyrolysis of FeCl₃ pre-soaking rice straw, could be a promising adsorbent for the remediation of complex As(V)-containing wastewater.

Predicting groundwater arsenic contamination: Regions at risk in highest populated state of India

Arsenic (As) contamination of groundwater is a public health concern, impacting the lives of approximately 100 million people in India. Chronic exposure to As significantly increases mortality due to the occurrence of several types of cancer, respiratory and cardiac diseases. Uttar Pradesh is a part of the middle Indo-Gangetic plains and has been found to be severely affected by As contamination of groundwater, as established by several small-scale studies. The current study incorporates a hybrid method based on a random forest ensemble algorithm and univariate feature selection using 1473 data points for predicting As in the region. Twenty direct/proxy predictor variables were considered to describe the geochemical environment, aquifer conditions and topography that are responsible for As enrichment in groundwater. The map of As predicted through the hybrid random forest ensemble model shows an overall accuracy of 84.67%. The hybrid random forest model performs better than the univariate, logistic, fuzzy, adaptive fuzzy and adaptive neuro fuzzy inference systems, which have been widely used for As prediction. The projected number of rural populations at risk due to high As exposure is 12% of the total population of the region, which accounts for 23.48 million people who are at risk. The predictive map provides insight for the regions where future testing campaigns and interventions for mitigation should be prioritized by policymakers.

Health risk assessment of drinking arsenic-containing groundwater in Hasilpur, Pakistan: effect of sampling area, depth, and source

Currently, several news channels and research publications have highlighted the dilemma of arsenic (As)-contaminated groundwater in Pakistan. However, there is lack of data regarding groundwater As content of various areas in Pakistan. The present study evaluated As contamination and associated health risks in previously unexplored groundwater of Hasilpur-Pakistan. Total of 61 groundwater samples were collected from different areas (rural and urban), sources (electric pump, hand pump, and tubewell) and depths (35-430 ft or 11-131 m). The water samples were analyzed for As level and other parameters such as pH, electrical conductivity, total dissolved solids, cations, and anions. It was found that 41% (25 out of 61) water samples contained As (≥ 5 μg/L). Out of 25 As-contaminated water samples, 13 water samples exceeded the permissible level of WHO (10 μg/L). High As contents have been found in tubewell samples and at high sampling depths (> 300 ft). The major As-contaminated groundwater in Hasilpur is found in urban areas. Furthermore, health risk and cancer risk due to As contamination were also assessed with respect to average daily dose (ADD), hazard quotient (HQ), and carcinogenic risk (CR). The values of HQ and CR of As in Hasilpur were up to 58 and 0.00231, respectively. Multivariate analysis revealed a positive correlation between groundwater As contents, pH, and depth in Hasilpur. The current study proposed the proper monitoring and management of well water in Hasilpur to minimize the As-associated health hazards.

Arsenic Contamination and Associated Health Risk (Brief Review)

The health risk assessment of residents consuming groundwater with high arsenic concentrations has attracted widespread concern. This study therefore is aimed at providing a framework to evaluate the risks imposed to local residents of Simaria Patti Ojha village of Bhojpur district, Bihar. Results showed that the mean values of ADD, HQ and CR were 5.1 µg/(Kg Day) (PTDI- 2.1 µg/(Kg Day), 5-17 (safe range <1) and 0.002-0.007(tolerable range, 10-6-10-4), respectively. Carcinogenic risk value was found as 4.7 × 10-3 around 100 times higher than safe range of 10−6–10−4, indicating high risks to the local residents. Hence, this study will help in suggesting suitable implementation measures on ground to deal with the risk of arsenic contamination and diseases caused due to its prolonged exposure.

Peripheral neuropathy induced by drinking water contaminated with low-dose arsenic in Myanmar

Background

More than 140 million people drink arsenic-contaminated groundwater. It is unknown how much arsenic exposure is necessary to cause neurological impairment. Here, we evaluate the relationship between neurological impairments and the arsenic concentration in drinking water (ACDW).

Participants and methods

A cross-sectional study design was employed. We performed medical examinations of 1867 residents in seven villages in the Thabaung township in Myanmar. Medical examinations consisted of interviews regarding subjective neurological symptoms and objective neurological examinations of sensory disturbances. For subjective neurological symptoms, we ascertained the presence or absence of defects in smell, vision, taste, and hearing; the feeling of weakness; and chronic numbness or pain. For objective sensory disturbances, we examined defects in pain sensation, vibration sensation, and two-point discrimination. We analyzed the relationship between the subjective symptoms, objective sensory disturbances, and ACDW.

Results

Residents with ACDW ≥ 10 parts per billion (ppb) had experienced a “feeling of weakness” and “chronic numbness or pain” significantly more often than those with ACDW < 10 ppb. Residents with ACDW ≥ 50 ppb had three types of sensory disturbances significantly more often than those with ACDW < 50 ppb. In children, there was no significant association between symptoms or signs and ACDW.

Conclusion

Subjective symptoms, probably due to peripheral neuropathy, occurred at very low ACDW (around 10 ppb). Objective peripheral nerve disturbances of both small and large fibers occurred at low ACDW (> 50 ppb). These data suggest a threshold for the occurrence of peripheral neuropathy due to arsenic exposure, and indicate that the arsenic concentration in drinking water should be less than 10 ppb to ensure human health.

High arsenic groundwater in the Guide basin, northwestern China: Distribution and genesis mechanisms

High arsenic (As) groundwater has been found in Pliocene confined aquifers at depths from 100 to 300 m of the Guide basin, but little is known on the main hydrogeochemical processes leading to its elevated concentrations. Ninety-seven water samples and fifty-three sediment samples were collected for chemical and/or isotopic analysis. Concentrations of As in groundwater of confined aquifer range from 9.9 to 377 μg/L (average 109 μg/L), which generally show a sharply increasing trend along with NH₄⁺, HCO₃^-, CO₃^2- and TOC along the inferred flow path, while NO₃^-, SO₄^2-/Cl^- and redox potential (Eh) have decreasing trends. Results of sequential extraction show that As bound to amorphous and crystalline Fe oxide minerals are the main As forms, accounting for around 50% of total As in sediments. Reductive dissolution of As-bearing Fe(III) oxide minerals under reducing conditions in confined aquifers lead to the mobilization of As in groundwater. In addition, alkaline environment and high concentrations of HCO₃^- and CO₃^2- may make contributions to As enrichment in groundwater. High As groundwater in confined aquifer continuously flows out on the ground surface through tens of artesian wells, which may potentially contaminate low As groundwater in unconfined aquifer. Thus, further investigation is needed to evaluate long-term variations of water chemistry of low As groundwater and assess vulnerability of unconfined aquifer to As contamination.

Developing robust arsenic awareness prediction models using machine learning algorithms

Arsenic awareness plays a vital role in ensuring the sustainability of arsenic mitigation technologies. Thus far, however, few studies have dealt with the sustainability of such technologies and its associated socioeconomic dimensions. As a result, arsenic awareness prediction has not yet been fully conceptualized. Accordingly, this study evaluated arsenic awareness among arsenic-affected communities in rural India, using a structured questionnaire to record socioeconomic, demographic, and other sociobehavioral factors with an eye to assessing their association with and influence on arsenic awareness. First a logistic regression model was applied and its results compared with those produced by six state-of-the-art machine-learning algorithms (Support Vector Machine [SVM], Kernel-SVM, Decision Tree [DT], k-Nearest Neighbor [k-NN], Naïve Bayes [NB], and Random Forests [RF]) as measured by their accuracy at predicting arsenic awareness. Most (63%) of the surveyed population was found to be arsenic-aware. Significant arsenic awareness predictors were divided into three types: (1) socioeconomic factors: caste, education level, and occupation; (2) water and sanitation behavior factors: number of family members involved in water collection, distance traveled and time spent for water collection, places for defecation, and materials used for handwashing after defecation; and (3) social capital and trust factors: presence of anganwadi and people's trust in other community members, NGOs, and private agencies. Moreover, individuals' having higher social network positively contributed to arsenic awareness in the communities. Results indicated that both the SVM and the RF algorithms outperformed at overall prediction of arsenic awareness-a nonlinear classification problem. Lower-caste, less educated, and unemployed members of the population were found to be the most vulnerable, requiring immediate arsenic mitigation. To this end, local social institutions and NGOs could play a crucial role in arsenic awareness and outreach programs. Use of SVM or RF or a combination of the two, together with use of a larger sample size, could enhance the accuracy of arsenic awareness prediction.

Groundwater Arsenic Contamination in the Ganga River Basin: A Future Health Danger

This study highlights the severity of arsenic contamination in the Ganga River basin (GRB), which encompasses significant geographic portions of India, Bangladesh, Nepal, and Tibet. The entire GRB experiences elevated levels of arsenic in the groundwater (up to 4730 µg/L), irrigation water (~1000 µg/L), and in food materials (up to 3947 µg/kg), all exceeding the World Health Organization’s standards for drinking water, the United Nations Food and Agricultural Organization’s standard for irrigation water (100 µg/L), and the Chinese Ministry of Health’s standard for food in South Asia (0.15 mg/kg), respectively. Several individuals demonstrated dermal, neurological, reproductive, cognitive, and cancerous effects; many children have been diagnosed with a range of arsenicosis symptoms, and numerous arsenic-induced deaths of youthful victims are reported in the GRB. Victims of arsenic exposure face critical social challenges in the form of social isolation and hatred by their respective communities. Reluctance to establish arsenic standards and unsustainable arsenic mitigation programs have aggravated the arsenic calamity in the GRB and put millions of lives in danger. This alarming situation resembles a ticking time bomb. We feel that after 29 years of arsenic research in the GRB, we have seen the tip of the iceberg with respect to the actual magnitude of the catastrophe; thus, a reduced arsenic standard for drinking water, testing all available drinking water sources, and sustainable and cost-effective arsenic mitigation programs that include the participation of the people are urgently needed.

Evaluation of water quality and human risk assessment due to heavy metals in groundwater around Muledane area of Vhembe District, Limpopo Province, South Africa

Groundwater is considered as good alternative to potable water because of its low turbidity and perceived low contamination. The study assessed the physio-chemical and heavy metals concentrations in eight randomly selected boreholes water at Muledane village in Limpopo Province of South Africa and the results were compared with South African National standard permissible limit. The impacts of heavy metals on human health was further determined by performing quantitative risk assessment through ingestion and dermal adsorption of heavy metals separately for adults and children in order to estimate the magnitude of heavy metals in the borehole samples. Parameters such as turbidity, nitrate, iron, manganese and chromium in some investigated boreholes did not comply with standard limits sets for domestic water use. Multivariate analyses using principal component analysis and hierarchical cluster analysis revealed natural and anthropogenic activities as sources of heavy metal contamination in the borehole water samples. The calculated non-carcinogenic effects using hazard quotient toxicity potential, cumulative hazard index and chronic daily intake of groundwater through ingestion and dermal adsorption pathways were less than a unity, which showed that consumption of the water could pose little or no significant health risk. However, maximum estimated values for an individual exceeded the risk limit of 10^-6 and 10^-4 with the highest estimated carcinogenic exposure risk (CR_ing) for Cr and Pb in the groundwater. This could pose potential health risk to both adults and children in the investigated area. Therefore, precaution needs to be taken to avoid potential CR_ing of people in Muledane area especially, children using the borehole water.

Human health risk constrained naphthalene-contaminated groundwater remediation management through an improved credibility method

In this study, a human health risk constrained groundwater remediation management program based on the improved credibility is developed for naphthalene contamination. The program integrates simulation, multivariate regression analysis, health risk assessment, uncertainty analysis, and nonlinear optimization into a general framework. The improved credibility-based optimization model for groundwater remediation management with consideration of human health risk (ICOM-HHR) is capable of not only effectively addressing parameter uncertainties and risk-exceeding possibility in human health risk but also providing a credibility level that indicates the satisfaction of the optimal groundwater remediation strategies with multiple contributions of possibility and necessity. The capabilities and effectiveness of ICOM-HHR are illustrated through a real-world case study in Anhui Province, China. Results indicate that the ICOM-HHR would generate double remediation cost yet reduce approximately 10 times of the naphthalene concentrations at monitoring wells, i.e., mostly less than 1 μg/L, which implies that the ICOM-HHR usually results in better environmental and health risk benefits. And it is acceptable to obtain a better environmental quality and a lower health risk level with sacrificing a certain economic benefit.

Arsenic-contaminated freshwater: assessing arsenate and arsenite toxicity and low-dose genotoxicity in Gammarus elvirae (Crustacea; Amphipoda)

Arsenic (As) contamination of freshwater is largely due to geogenic processes, but As is also released into the environment because of improper anthropic activities. The European regulatory limits in drinking water are of 10 μg L^-1 As. However, knowledge of the genotoxic effects induced by low doses of As in freshwater environments is still scanty. This study was designed to investigate arsenate (As(V)) and arsenite (As(III)) toxicity and low-dose genotoxicity in Gammarus elvirae, which has proved to be a useful organism for genotoxicity assays in freshwater. As(V) and As(III) toxicity was assessed on the basis of the median lethal concentration, LC(50), while estimates of DNA damage were based on the Comet assay. The G. elvirae LC (50-240 h) value we calculated was 1.55 mg L^-1 for As(V) and 1.72 mg L^-1 for As(III). Arsenic exposure (240 h) at 5, 10, and 50 µg L^-1 of As in assays with either arsenate or arsenite-induced DNA damage in hemocytes of G. elvirae in a concentration-dependent manner. Our study provides a basis for future genotoxic research on exposure to freshwater that contains low levels of arsenic.

Molecular insight of arsenic-induced carcinogenesis and its prevention

Population of India and Bangladesh and many other parts of the world are badly exposed to arsenic through drinking water. Due to non-availability of safe drinking water, they are dependent on arsenic-contaminated water. Generally, poverty level is high in those areas with lack of proper nutrition. Arsenic is considered to be an environmental contaminant and widely distributed in the environment due to its natural existence and anthropogenic applications. Contamination of arsenic in both human and animal could occur through air, soil, and other sources. Arsenic exposure mainly occurs in food materials through drinking water with high levels of arsenic in it. High levels of arsenic in groundwater have been found to be associated with various health-related problems including arsenicosis, skin lesions, cardiovascular diseases, reproductive problems, psychological, neurological, immunotoxic, and carcinogenesis. The mechanism of arsenic toxicity consists in its transformation in metaarsenite, which acylates protein sulfhydryl groups, affect on mitochondria by inhibiting succinic dehydrogenase activity and can uncouple oxidative phosphorylation with production of active oxygen species by tissues. A variety of dietary antioxidant supplements are useful to protect the carcinogenetic effects of arsenic. They play crucial role for counteracting oxidative damage and protect carcinogenesis by chelating with heavy metal moiety. Phytochemicals and chelating agents will be beneficial for combating heavy metal-induced carcinogenesis through its biopharmaceutical properties.

Determination of total arsenic and arsenic species in drinking water, surface water, wastewater, and snow from Wielkopolska, Kujawy-Pomerania, and Lower Silesia provinces, Poland

Arsenic is a ubiquitous element which may be found in surface water, groundwater, and drinking water. In higher concentrations, this element is considered genotoxic and carcinogenic; thus, its level must be strictly controlled. We investigated the concentration of total arsenic and arsenic species: As(III), As(V), MMA, DMA, and AsB in drinking water, surface water, wastewater, and snow collected from the provinces of Wielkopolska, Kujawy-Pomerania, and Lower Silesia (Poland). The total arsenic was analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and arsenic species were analyzed with use of high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC/ICP-MS). Obtained results revealed that maximum total arsenic concentration determined in drinking water samples was equal to 1.01 μg L(-1). The highest concentration of total arsenic in surface water, equal to 3778 μg L(-1) was determined in Trująca Stream situated in the area affected by geogenic arsenic contamination. Total arsenic concentration in wastewater samples was comparable to those determined in drinking water samples. However, significantly higher arsenic concentration, equal to 83.1 ± 5.9 μg L(-1), was found in a snow sample collected in Legnica. As(V) was present in all of the investigated samples, and in most of them, it was the sole species observed. However, in snow sample collected in Legnica, more than 97 % of the determined concentration, amounting to 81 ± 11 μg L(-1), was in the form of As(III), the most toxic arsenic species.