Groundwater arsenic contamination in one of the 107 arsenic-affected blocks in West Bengal, India: Status, distribution, health effects and factors responsible for arsenic poisoning

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.

Appraisal of treated drinking water quality from arsenic removal units in West Bengal, India: Approach on safety, efficiency, sustainability, future health risk and socioeconomics

The present study depicts the true failed scenario of the arsenic (As) removal units (ARU) in West Bengal by evaluating their treated water quality. Annual As removal efficiency of the 12 studied ARUs range between 35.2% and 82.6%. A comprehensive physico-chemical parameters and trace elements analysis find almost 25% and 16.7% of treated drinking water samples with poor water quality index (WQI) and high heavy metal evaluation index (HEI), respectively. The pond-based water treatment plant maintains the production of continuous As-safe water with a range between 60.2% and 66.7% due to its high Fe/As ratio. It's a discontent concluding the treated drinking water of the groundwater based-ARUs were observed with sufficient As mediated cancer risk (3 ×10-3). The non-cancer risk (HQ) of As is safe for the surface water treatment plant (0.38), whereas it is threatening for the groundwater based-ARUs (7.44). However, the drinking water samples are safe in view of HQ from the other trace elements like Hg, Al, Cd, Cr, Pb, F- and NO3-. Small scale ARU could be a feasible mitigation strategy in reducing the As menace in the long run if the plants are maintained correctly. Nevertheless, surface treated water is the most sustainable solution as withdrawal of groundwater for drinking purpose is not a viable practice.

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.

Different levels of arsenic exposure through cooked rice and its associated benefit-risk assessment from rural and urban populations of West Bengal, India: a probabilistic approach with sensitivity analysis

Rice arsenic (As) contamination and its consumption poses a significant health threat to humans. The present study focuses on the contribution of arsenic, micronutrients, and associated benefit-risk assessment through cooked rice from rural (exposed and control) and urban (apparently control) populations. The mean decreased percentages of As from uncooked to cooked rice for exposed (Gaighata), apparently control (Kolkata), and control (Pingla) areas are 73.8, 78.5, and 61.3%, respectively. The margin of exposure through cooked rice (MoE_{cooked rice}) < 1 signifies the existence of health risk for all the studied exposed and control age groups. The respective contributions of iAs (inorganic arsenic) in uncooked and cooked rice are nearly 96.6, 94.7, and 100% and 92.2, 90.2, and 94.2% from exposed, apparently control, and control areas. LCR analysis for the exposed, apparently control, and control populations (adult male: 2.1 × 10^-3, 2.8 × 10^-4, 4.7 × 10^-4; adult female: 1.9 × 10^-3, 2.1 × 10^-4, 4.4 × 10^-4; and children: 5.8 × 10^-4, 4.9 × 10^-5, 1.1 × 10^-4) through cooked rice is higher than the recommended value, i.e., 1 × 10^-6, respectively, whereas HQ > 1 has been observed for all age groups from the exposed area and adult male group from the control area. Adults and children from rural area showed that ingestion rate (IR) and concentration are the respective influencing factors towards cooked rice As, whereas IR is solely responsible for all age groups from urban area. A vital suggestion is to reduce the IR of cooked rice for control population to avoid the As-induced health risks. The average intake (μg/day) of micronutrients is in the order of Zn > Se for all the studied populations and Se intake is lower for the exposed population (53.9) compared to the apparently control (140) and control (208) populations. Benefit-risk assessment supported that the Se-rich values in cooked rice are effective in avoiding the toxic effect and potential risk from the associated metal (As).

Iron oxide doped rice biochar reduces soil-plant arsenic stress, improves nutrient values: An amendment towards sustainable development goals

Arsenic (As) contamination in paddy soils and its further translocation to the rice is a serious global issue. Arsenic loading to the rice depends on soil physico-chemical parameters and agronomic practices. To minimize this natural threat, as a natural substance, rice straw was used to produce rice biochar (RBC) and doped with iron oxide (IO) nanoparticles, another eco-friendly composite. In this study, RBC was used at three different concentrations- 0.5%, 1%, and 1.5% alone as well as conjugated with fixed 20 ppm IO nanoparticles. These treatments were compared with the control soil and control plants that had only As in the setup, without any amendments. The application of these treatments was efficient in reducing soil As bioavailability by 43.9%, 60.5%, and 57.3% respectively. Experimental data proved a significant percentage of As was adsorbed onto the RBC + IO conjugate. Further, the 1% RBC + IO conjugate was found to be the best treatment in terms of making soil macro-nutrients bioavailable. Rice seedlings grown under this treatment was more stress tolerant and produced less antioxidant enzymes and stress markers compared to the control plants grown under As-stress only. Rice plants from these different growth setups were observed for internal anatomical integrity and found that the RBC alone and RBC + IO conjugate, both improved the internal vascular structure compared to the control plants. To minimize soil As stress in crops, IO-doped RBC was proven to be the best sustainable amendment for improving soil-crop quality and achieving the proposed motto of Sustainable Development Goals by the United Nations.

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.

Arsenic toxicity in livestock growing in arsenic endemic and control sites of West Bengal: risk for human and environment

The present study aims to estimate geochemical arsenic toxicity in the domestic livestock and possible risk for human and environment caused by them. Daily dietary arsenic intake of an exposed adult cow or bull is nearly 4.56 times higher than control populace and about 3.65 times higher than exposed goats. Arsenic toxicity is well exhibited in all the biomarkers through different statistical interpretations. Arsenic bioconcentration is faster through water compared to paddy straw and mostly manifested in faeces and tail hair in cattle. Cow dung and tail hair are the most pronounced pathways of arsenic biotransformation into environment. A considerable amount of arsenic has been observed in animal proteins such as cow milk, boiled egg yolk, albumen, liver and meat from the exposed livestock. Cow milk arsenic is mostly accumulated in casein (83%) due to the presence of phosphoserine units. SAMOE-risk thermometer, calculated for the most regularly consumed foodstuffs in the area, shows the human health risk in a distinct order: drinking water > rice grain > cow milk > chicken > egg > mutton ranging from class 5 to 1. USEPA health risk assessment model reveals more risk in adults than in children, subsisting severe cancer risk from the foodstuffs where the edible animal proteins cannot be ignored. Therefore, the domestic livestock should be urgently treated with surface water, while provision of both arsenic-free drinking water and nutritional supplements is mandatory for the affected human population to overcome the severe arsenic crisis situation.

Arsenic and Its Effect on Nutritional Properties of Oyster Mushrooms with Reference to Health Risk Assessment

Arsenic (As) contamination is endemic in West Bengal, India. Arsenic exposure through mushroom is lethal to health. Pleurotus sp. is globally consumed as food for its medicinal and nutritional values. This study was performed to evaluate the arsenic accumulation in mushroom through arsenic biomagnified rice straw substrate in relation to health risk assessment. Arsenic concentrations were higher in P. ostreatus (12.577 mg/kg DW) and Pleurotus sp. (12.446 mg/kg DW) cultivated in arsenic biomagnified rice straw as compared with P. ostreatus (0.472 mg/kg DW) and Pleurotus sp. (0.434 mg/kg DW) cultivated in non-contaminant rice straw; respectively. The bio-concentration factor (BCF) value of arsenic was highest in stem at 3rd flush for both P. ostreatus and Pleurotus sp. The health risk index (HRI) based on dietary intake of these arsenic biomagnified mushrooms was found moderately higher in both the species, so higher intake of these mushrooms will put people at health risk.

Monsoonal paddy cultivation with phase-wise arsenic distribution in exposed and control sites of West Bengal, alongside its assimilation in rice grain

The present study mainly deals with monsoonal paddy farming with respect to its phase-wise arsenic (As) accumulation and distribution throughout cultivation in As exposed sites and control areas of West Bengal for two consecutive years, 2017 and 2018. Arsenic uptake in paddy depends on the watering pattern with the help of groundwater (Madhusudhankati: 171 μg/l, Teghoria: 493 μg/l in Gaighata and Pingla: 10 μg/l in Medinipur), soil As phase-wise movement with its enrichment pattern and the variation of rainfall. Arsenic mobility is the highest in root and decreases with height of a plant. However, the synergistic effect of groundwater and rainwater makes a diffused approach to the nature of As flow in plants, because rainwater has a pivotal role in diluting the As content available for translocation. Reproductive phase accumulates maximum As compared to vegetative and ripening phases. Sequential extraction and SEM studies re-confirm no possibility of iron (Fe) plaque formation in root soils which sequestered As. Finally, we conclude that monsoonal cultivation provides least As enriched grain (exposed area: 350 μg/kg, control area: 224 μg/kg) irrespective of the variety of cultivar and area of cultivation, which amounts to one-third of pre-monsoonal grain (1120 μg/kg) and so, it is much safer for consumption with respect to As and micro-nutrient status.

Flow of arsenic between rice grain and water: Its interaction, accumulation and distribution in different fractions of cooked rice

Arsenic (As) contaminated water is a major threat to human health when used for drinking, cooking and irrigational purposes. Rice being consumed by 50% of the world's population, supplies considerable amount of As to the human body. Our study provides a detailed understanding of As distribution in each fraction of rice while cooking (viz. uncooked rice, cooking water, cooked rice and gruel/total discarded water), ultimately leading to a better explanation of As movement between rice grain and water. A significant decrease of As was observed in cooked rice (34-89% and 23-84% for sunned and parboiled rice respectively) when cooked with low-As containing water, <3 μg/l and moderate As-contaminated water, 36-58 μg/l (3-50% and 12-61% for sunned and parboiled rice respectively) with increasing selenium (Se) concentration. Movement of As from water to rice grain has been inferred with increasing water As (84-105 μg/l), which results in a significant increase of As in cooked rice (24-337% and 114% for sunned and parboiled rice, respectively) with decreasing Se concentration. Arsenic speciation study emphasizes the fact of similar reduction percentage of As (III), As (V) and total As in wet cooked rice when cooked with low-As containing water. The SAMOE value in 'risk thermometer' supports the higher risk of suffering from wet cooked rice (class 4) with increasing cooking water As concentration (class 3 to class 5).

Synthesis of novel adsorbent by intercalation of biopolymer in LDH for the removal of arsenic from synthetic and natural water

This study focuses on the synthesis of nanocomposites named CCA and CZA that were prepared by the incorporation of cellulose (CL) in the Ca/Al and Zn/Al layered double hydroxide (LDH), respectively. These materials were then used for the uptake of As(III) and As(V) from aqueous medium. Characterization of both nanocomposites (CCA and CZA) was done using FTIR and Raman analysis to identify the functional groups, N₂ adsorption-desorption isotherms to determine the specific surface area and pore geometry and XPS analysis to obtain the surface atomic composition. Some other characters were investigated using simultaneous TGA and DTA and elemental chemical analysis (CHNS/O). The crystallinity of the prepared nanocomposites was displayed by XRD patterns. Furthermore, the sheet-like structure of the LDHs and the irregularity of surface morphology with porous structure were observed by TEM and SEM microphotographs. Optimization of maximum adsorption capacity was adjusted using different parameters including pH, contact time and adsorbent dosage. The pseudo-second-order model was in good fitting with kinetics results. The adsorption isotherm results showed that CZA exhibits better adsorption capacity for As(III) than CCA and the Langmuir isotherm model described the data well for both nanocomposites. Thermodynamic studies illustrated the endothermic nature of CCA and exothermic nature on CZA, as well as the fact that the adsorption process is spontaneous. A real water sample collected from well located in Gabes (Tunisia), has also been treated. The obtained experimental results were confirmed that these sorbents are efficient for the treatment of hazardous toxic species such as.

Microbial and plant-assisted heavy metal remediation in aquatic ecosystems: a comprehensive review

Heavy metal (HM) pollution in aquatic ecosystems has an adverse effect on both aquatic life forms as well as terrestrial living beings, including humans. Since HMs are recalcitrant, they accumulate in the environment and are subsequently biomagnified through the food chain. Conventional physical and chemical methods used to remove the HMs from aquatic habitats are usually expensive, slow, non-environment friendly, and mostly inefficient. On the contrary, phytoremediation and microbe-assisted remediation technologies have attracted immense attention in recent years and offer a better solution to the problem. These newly emerged remediation technologies are eco-friendly, efficient and cost-effective. Both phytoremediation and microbe-assisted remediation technologies adopt different mechanisms for HM bioremediation in aquatic ecosystems. Recent advancement of molecular tools has contributed significantly to better understand the mechanisms of metal adsorption, translocation, sequestration, and tolerance in plants and microbes. Albeit immense possibilities to use such bioremediation as a successful environmental clean-up technology, it is yet to be successfully implemented in the field conditions. This review article comprehensively discusses HM accumulation in Indian aquatic environments. Furthermore, it describes the effect of HMs accumulation in the aquatic environment and the role of phytoremediation as well as microbe-assisted remediation in mitigation of the HM toxicity. Finally, the review concludes with a note on the challenges, opportunities and future directions for bioremediation in the aquatic ecosystems.

Characterization, concentration and risk assessment of airborne particles using car engine air filter (case study: Tehran metropolis)

Atmospheric elements released into the atmosphere can enter the human body through inhalation, ingestion and dermal contact and are then deposited in the body. Trace elements have potential risks to human health. For this purpose, the particulate matter accumulated by car air filters (CAFs) was studied. The morphology and distribution of particle size were examined using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The concentration of elements in CAFs and CAF-estimated air for 30 elements in Tehran, Iran, was analyzed in winter and summer, from February to July 2017. Samples were determined by inductively coupled mass plasma spectrometry. The most abundantly detected elements in both CAFs and air in both seasons were Ca, Mg, Na and Fe. The shape of the particles was mostly irregular and spherical. Most of the particles were between 0.5 and 1.0 µm. The carcinogenic risks of inhalation exposure to Cr and Co in winter and summer were higher than the acceptable level (< 1 × 10^-4) for children and adults. The carcinogenic risks of As and Cr in both seasons were higher than 1 × 10^-4 for children and adults via dermal contact. Also, the carcinogenic risks of Cr in both seasons of ingestion exposure were higher than 1.00E-04 for children and adults. The integrated noncarcinogenic risks of all trace elements were higher than the safe level (= 1) for children and adults in both seasons.

Removal of Pb (II), As (III), and Cr (VI) by nitrogen-starved Papiliotrema laurentii strain RY1

Heavy metals such as lead, chromium, and metalloid like arsenic dominate the pinnacle in posing a threat to life. Being environment-friendly, elucidating the mechanism by which microorganisms detoxify such elements has always been an active field of research hitherto. In the present study, we have investigated the capability of nitrogen-deprived Papiliotrema laurentii strain RY1 toward enhanced tolerance and neutralizing toxic elements. There were biosorption and bioprecipitation of lead and chromium at the cell surfaces. Bioprecipitation mechanisms included the formation of lead phosphates and pyromorphites from lead, grimaldite from chromium. Transcripts such as metallothionein, aquaporins, and arsenical pump-driving ATPase have been surmised to be involved in the detoxification of elements. Furthermore, activation of antioxidant defense mechanisms for the cells for each of the elements should contribute towards yeast's propagation. The efficiency of removal of elements for live cells and immobilized cells were high for lead and chromium. To the best of our knowledge, this is the first report of such high tolerance of lead, arsenic, and chromium for any yeast. The yeast showed such varied response under dual stress due to nitrogen starvation and in the presence of respective elements. The yeast possesses promising potentials in nitrogen deprived and enriched environments to aid in bioremediation sectors.

Arsenic contamination in Kolkata metropolitan city: perspective of transportation of agricultural products from arsenic-endemic areas

Arsenic exposure route for humans is through the drinking of contaminated water and intake of arsenic-contaminated foods, particularly in arsenic-exposed areas of Bengal delta. Transport of the arsenic-contaminated crops and vegetables grown using arsenic-contaminated groundwater and soil in arsenic-exposed areas to the uncontaminated sites and consequent dietary intakes leads to great threats for the population residing in non-endemic areas with respect to consumption of arsenic through drinking water. We have studied the food materials collected from 30 families and their dietary habits, apparently who consume arsenic-free drinking water as well as 9 well-known markets of Kolkata city. The total and inorganic arsenic intake has been estimated from the collected foodstuffs from the market basket survey (n = 93) and household survey (n = 139), respectively for human risk analysis. About 100% of the collected samples contained detectable amount of arsenic (range 24-324 μg/kg), since the origin of the food materials was somewhere from arsenic-endemic areas. The daily consumption of inorganic arsenic (iAs) from rice grain and vegetables for adult and children is 76 μg and 41.4 μg, respectively. Inorganic arsenic (mainly arsenite and arsenate) contributes approximately 88% of the total content of arsenic in vegetable. In most of the cases, insufficient nutrient intake by the studied population may lead to arsenic toxicity in the long run. An independent cancer risk assessment study on the same population indicates that the main risk of cancer might appear through the intake of arsenic-contaminated rice grain and cereals.

Arsenic accumulation in paddy plants at different phases of pre-monsoon cultivation

Geogenic arsenic (As) contamination in Bengal Delta Plain is a growing environmental and research concern. Cultivation of staple crops like paddy on these contaminated fields is one of the major routes for human dietary exposure. The present study investigates changes of arsenic concentrations in paddy plant parts, root soil and surface soil throughout the various phases of pre-monsoon (boro) cultivation. Arsenic uptake property of paddy plants collected from 10 fields was found to be dependent on the variety of paddy plant (like Minikit, Jaya) rather than arsenic levels in groundwater (0.074-0.301 mg/l) or soil (25.3-60 mg/kg). Arsenic is translocated from root to aerial parts in descending order. Leaf, stem, root, root soil and surface soil showed a similar trend in their change of arsenic concentration throughout the cultivation period. Arsenic concentration was highest in vegetative phase; sharply declined in reproductive phase; followed by moderate increase in ripening phase. The young root tissues in vegetative (primary) phase could uptake arsenic at a much faster rate than the older tissues in later phases. With the growth of the plant, higher concentrations of iron in root soil in the reproductive phase confirmed the formation of iron plaques on the surface of the root, which sequester arsenic and prevented its uptake by plants. Finally, co-precipitation of arsenic with iron released from crystallized iron plaques results in loosening of the iron plaques from root surface. Thus, soil arsenic concentration increases in the final phase of cultivation which in turn contributes to increased concentration in plant parts.

Impact of arsenic contaminated groundwater used during domestic scale post harvesting of paddy crop in West Bengal: Arsenic partitioning in raw and parboiled whole grain

The role of post harvesting procedures for producing parboiled rice grain using arsenic (As) contaminated groundwater in rural Bengal was investigated. Considerable high concentrations of As (mean: 186 μg/kg) were found in about 82% of parboiled rice grain samples compared to raw or non-parboiled rice grain samples (66 μg/kg in 75% samples) obtained from Deganga, a highly As affected zone located in West Bengal, India. This observation instigated to study the additional entry of As at various stages of parboiling. A maximum increase of 205% of As content in parboiled rice grain was observed. Significant increase in parboiled whole grain As concentration was dependent upon the large difference between As concentrations of the water and the raw whole grain used for parboiling. Arsenic concentrations of water samples collected at raw, half boiled and full boiled stages of parboiling increased, irrespective of their initial concentration due to reduction in final volume during parboiling process. Principle component analysis shows a positive correlation of As concentration of rice grain to that in the groundwater being used in post harvesting procedure. Moreover, partitioning studies of As in whole grain indicated higher accumulation of As content in individual rice grain than that in their respective husks implying higher risk of exposure on ingestion of these contaminated rice grains. It is therefore, suggested to employ novel methods such as rain water harvesting or surface water channelling to make As free water available for parboiling process to curtail the entry of additional As in parboiled rice.

Opportunities and challenges in the use of mineral nutrition for minimizing arsenic toxicity and accumulation in rice: A critical review

Growing rice on arsenic (As)-contaminated soil or irrigating with As-contaminated water leads to significant accumulation of As in grains. Moreover, rice accumulates more As into grains than other cereal crops. Thus, rice consumption has been identified as a major route of human exposure to As in many countries. Inorganic As species are carcinogenic and could pose a considerable health risk to humans even at low dietary concentration. Genotypic variation and concentration of nutrients such as iron, manganese, phosphate, sulfur and silicon are the two main factors that affect As accumulation in rice grains. Therefore, in addition to better growth and yield of plants, application of specific nutrients in optimum quantities offers an added benefit of decreasing As content in rice grains. These nutrient elements influence speciation of As in rhizosphere, compete with As for root uptake and interfere with As translocations to the shoot and ultimately accumulation in grains. This papers critically appraises the methods, forms and rate of application, mechanisms and extent of efficiency of different mineral nutrients in decreasing As accumulation in rice grains.

Using urine as a biomarker in human exposure risk associated with arsenic and other heavy metals contaminating drinking groundwater in intensively agricultural areas of Thailand

Urine used as a biomarker was collected and compared between two groups of participants: (1) a groundwater-drinking group and (2) a non-groundwater-drinking group in intensively agricultural areas in Ubon Ratchathani province, Thailand. The statistical relationship with the metal concentration in shallow groundwater wells was established with urine data. According to the groundwater data, the health risk assessment results for four metals appeared to be higher for participants who drank groundwater than for the other group. The carcinogenic risk and non-carcinogenic risk of arsenic (As) were found in 25.86 and 31.03% of participants, respectively. For lead (Pb), 13.79% of the participants had a non-carcinogenic risk. Moreover, 30 of the 58 participants in the groundwater-drinking group had As urine higher than the standard, and 26, 2 and 9 of the 58 participants had above-standard levels for cadmium (Cd), Pb and mercury (Hg) in urine, respectively. Both the risk assessment and biomarker level of groundwater-drinking participants were higher than in the other group. The results showed an average drinking rate of approximately 4.21 ± 2.73 L/day, which is twice as high as the standard. Interestingly, the As levels in the groundwater correlated with those in the urine of the groundwater-drinking participants, but not in the non-groundwater-drinking participants, as well as with the As-related cancer and non-carcinogenic risks. The hazard index (HI) of the 100 participants ranged from 0.00 to 25.86, with an average of 1.51 ± 3.63 higher than the acceptable level, revealing that 28 people appeared to have non-carcinogenic risk levels (24 and 4 people for groundwater-drinking participants and non-groundwater-drinking participants, respectively). Finally, the associated factors of heavy metals in urine were the drinking water source, body weight, smoking, sex and use of personal protective equipment.

Human exposure assessment of different arsenic species in household water sources in a high risk arsenic area

Understanding arsenic speciation in water is important for managing the potential health risks associated with chronic arsenic exposure. Most arsenic monitoring studies to date have only measured total arsenic, with few looking at arsenic species. This study assessed 228 ground water sources in six unstudied villages in Pakistan for total, inorganic and organic arsenic species using ion chromatography inductively coupled plasma collision reaction cell mass spectrometry. The concentration levels approached 3090μgL^-1 (95% CI, 130.31, 253.06) for total arsenic with a median of 57.55μgL^-1, 3430μgL^-1 (median=52) for arsenate (As⁺⁵) and 100μgL^-1 (median=0.37) for arsenite (As⁺³). Exceedance of the WHO provisional guideline value for arsenic in drinking water (10μgL^-1) occurred in 89% of water sources. Arsenic was present mainly as arsenate (As⁺⁵). Average daily intake of total arsenic for 398 residents living in the sampled houses was found up to 236.51μgkg^-1day^-1. This exposure estimate has indicated that 63% of rural residents exceeded the World Health Organization's provisional tolerable daily intake (PTDI) of 2.1μgkg^-1day^-1 body weight. Average daily intake of As⁺⁵ was found to be 15.63μgkg^-1day^-1 (95% CI, 5.53, 25.73) for children ≤16 and 15.07μgkg^-1day^-1 (95% CI, 10.33, 18.02) for adults. A mean daily intake of 0.09μgkg^-1day^-1 was determined for As⁺³ for children and 0.26μgkg^-1day^-1 for adults. Organic arsenic species such as monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and Arsenobetaine (AsB) were found to be below their method detection limits (MDLs).

Arsenic and dichlorvos: Possible interaction between two environmental contaminants

Metals are ubiquitously present in the environment and pesticides are widely used throughout the world. Environmental and occupational exposure to metal along with pesticide is an area of great concern to both the public and regulatory authorities. Our major concern is that combination of these toxicant present in environment may elicit toxicity either due to additive or synergistic interactions or 'joint toxic actions' among these toxicants. It poses a rising threat to human health. Water contamination particularly ground water contamination with arsenic is a serious problem in today's scenario since arsenic is associated with several kinds of health problems, such arsenic associated health anomalies are commonly called as 'Arsenism'. Uncontrolled use and spillage of pesticides into the environment has resulted in alarming situation. Moreover serious concerns are being addressed due to their persistence in the environmental matrices such as air, soil and surface water runoff resulting in continuous exposure of these harmful chemicals to human beings and animals. Bio-availability of these environmental toxicants has been enhanced much due to anthropological activities. Dreadfully very few studies are available on combined exposures to these toxicants on the animal or human system. Studies on the acute and chronic exposure to arsenic and DDVP are well reported and well defined. Arsenic is a common global ground water contaminant while dichlorvos is one of the most commonly and widely employed organophosphate based insecticide used in agriculture, horticulture etc. There is thus a real situation where a human may get exposed to these toxicants while working in a field. This review highlights the individual and combined exposure to arsenic and dichlorvos on health.

Arsenic(V) biosorption by charred orange peel in aqueous environments

Biosorption efficiency of natural orange peel (NOP) and charred orange peel (COP) was examined for the immobilization of arsenate (As(V)) in aqueous environments using batch sorption experiments. Sorption experiments were carried out as a function of pH, time, initial As(V) concentration and biosorbent dose, using NOP and COP (pretreated with sulfuric acid). Arsenate sorption was found to be maximum at pH 6.5, with higher As(V) removal percentage (98%) by COP than NOP (68%) at 4 g L(-1) optimum biosorbent dose. Sorption isotherm data exhibited a higher As(V) sorption (60.9 mg g(-1)) for COP than NOP (32.7 mg g(-1)). Langmuir model provided the best fit to describe As(V) sorption. Fourier transform infrared spectroscopy and scanning electron microscopy combined with energy dispersive X-ray spectroscopy analyses revealed that the -OH, -COOH, and -N-H surface functional groups were involved in As(V) biosorption and the meso- to micro-porous structure of COP sequestered significantly (2-times) higher As(V) than NOP, respectively. Arsenate desorption from COP was found to be lower (10%) than NOP (26%) up to the third regeneration cycle. The results highlight that this method has a great potential to produce unique 'charred' materials from the widely available biowastes, with enhanced As(V) sorption properties.

Levels of arsenic pollution in daily foodstuffs and soils and its associated human health risk in a town in Jiangsu Province, China

The development of industries in rural areas can aggravate the arsenic (As) contamination of the local environment, which may pose unacceptable health risks to the local residents. This paper estimated the health risk posed by inorganic As (iAs) to residents via ingestion of soil, skin contact with soil and consumption of foodstuffs in a typical rural- industrial developed town in southern Jiangsu, China. The average concentrations of total As in soil, rice, fish, shrimp and crab, pork and eggs, vegetables and fruits were detected to be 10.367, 0.104 mg/kg dw (dry weight), 0.050, 0.415, 0.011, 0.013 and 0.017 mg/kg fw (fresh weight), respectively. All of these values are below the maximum allowable concentration in food and soil in China. The deterministic estimation results showed that the hazard quotient (HQ) and excess lifetime cancer risk (R) were 1.28 (0.78-2.31) and 2.38 × 10(-4) (2.71 × 10(-5)-5.09 × 10(-4)) for all age groups, respectively. Males in the age range of 2-29 years and females in the age range of 2-13 years and 18-29 years exhibited non-carcinogenic risk (HQ>1). Carcinogenic risk exceeded the acceptable level of 1 × 10(-)(5) for both genders at all ages. Furthermore, this risk rose with age. The probabilistic estimation results showed that about 28% of residents had non-carcinogenic risk due to over ingestion of iAs. The R value of 90% of residents was greater than 10(-)(5). The sensitivity analysis indicated that the cancer slope factor (SF), the ingestion rates of rice and the iAs concentration in rice were the most relevant variables affecting the assessment outcome. Based on these results, it is recommended that residents reduce their consumption of rice, though it should be noted that the assessment outcome has uncertainty due to estimating iAs from foodstuffs and not considering the bioaccessibility of iAs in foodstuffs. Nevertheless, measures like reducing industrial As emissions, forbidding the use of pesticides, fertilizers and sludge which contain As and optimizing water management in rice paddy fields should be taken to mitigate the risks.

Assessing arsenic intake from groundwater and rice by residents in Prey Veng province, Cambodia

We investigated total daily intake of As by residents in Prey Veng province in the Mekong River basin of Cambodia. Groundwater (n = 11), rice (n = 11) and fingernail (n = 23) samples were randomly collected from the households and analyzed for total As by inductively coupled plasma mass spectrometry. Calculation indicated that daily dose of inorganic As was greater than the lower limits on the benchmark dose for a 0.5% increased incidence of lung cancer (BMDL0.5 equals to 3.0 μg d(-1) kg(-1)body wt.). Moreover, positive correlation between As in fingernail and daily dose of As from groundwater and rice and total daily dose of As were found. These results suggest that the Prey Veng residents are exposed to As in groundwater. As in rice is an additional source which is attributable to high As accumulation in human bodies in the Mekong River basin of Cambodia.

Biological oxidation of arsenite in synthetic groundwater using immobilised bacteria

Biological oxidation of arsenite (As(III)) in synthetic groundwater was examined by using arsenite oxidising bacteria (AOB) isolated from an activated sludge. The phylogenetic analysis indicated that the isolated AOB was closely related to Ensifer adhaerens. Batch experiments showed that for an As(III) oxidation with the isolated AOB the optimum ratio of nitrogen source (NH₄-N) concentration to As(III) concentration was 0.5 (52 mg/L-110 mg/L) and the isolated AOB preferred pH values ranging from 6 to 8, and water temperatures greater than 20 °C. Further continuous experiments were conducted using a bioreactor with immobilised AOB. With an initial As(III) concentration of 1 mg/L at a hydraulic retention time (HRT) of 1 h, an As(III) oxidation rate was around 1 × 10⁻⁹ μg/cell/min and an As(III) oxidation efficiency of 92% was achieved. Although the maximum oxidation rate measured at an HRT of 0.5 h was 2.1 × 10⁻⁹ μg/cell/min, the oxidation efficiency decreased to 87%. These results advocate that a biological process involving immobilised AOB may be useful as an economical and environmentally friendly pre-treatment step for As removal from groundwater.

Arsenic-contaminated cold-spring water in mountainous areas of Hui County, Northwest China: a new source of arsenic exposure

Although pump-well is the primary drinking water source in rural areas of China, there are still 8.4% of villages reliant on cold-spring. In this study, a survey of arsenic concentration in cold-springs and pump-wells was carried out in Hui County, Northwest China. A total of 352 drinking water samples, including 177 cold-springs and 175 pump-wells, were collected. The maximum arsenic concentrations in cold-springs and pump-wells were 0.482 mg/L and 0.067 mg/L, respectively. We found that 15.8% (28) of total cold-springs and 1.1% (2) of total pump-wells had arsenic concentrations exceeding the maximum allowable concentration of arsenic in drinking water of rural China (0.05 mg/L). Our findings show that 5 cold spring-contaminated villages are located in the mountainous areas of Hui County and 2224 inhabitants may be at risk of high arsenic exposure. This paper indicates that arsenic contamination of cold-springs may be more serious than expected in mountainous areas of Northwest China and extensive surveys and epidemiological studies should be carried out to investigate the potential contaminated areas and affected population.

Effects of abandoned arsenic mine on water resources pollution in north west of iran

BACKGROUND

Pollution due to mining activities could have an important role in health and welfare of people who are living in mining area. When mining operation finishes, environ-ment of mining area can be influenced by related pollution e.g. heavy metals emission to wa-ter resources. The present study was aimed to evaluate Valiloo abandoned arsenic mine ef-fects on drinking water resources quality and possible health effects on the residents of min-ing area in the North West of Iran.

METHODS

Water samples and some limited composite wheat samples in downstream of min-ing area were collected. Water samples were analyzed for chemical parameters according to standard methods. For determination of arsenic in water samples, Graphite Furnace Atomic Absorption Spectrometric Method (GFAAS) and for wheat samples X - Ray Fluorescence (XRF) and Inductively Coupled Plasma Method (ICP) were used. Information about possible health effects due to exposure to arsenic was collected through interviews in studied villages and health center of Herris City.

RESULTS

The highest concentrations of arsenic were measured near the mine (as high as 2000 µg/L in Valiloo mine opening water). With increasing distance from the mine, concentration was decreased. Arsenic was not detectable in any of wheat samples. Fortunately, no health effects had been reported between residents of studied area due to exposure to arsenic.

CONCLUSION

Valiloo abandoned arsenic mine has caused release of arsenic to the around en-vironment of the mine, so arsenic concentration has been increased in the groundwater and also downstream river that requires proper measures to mitigate spread of arsenic.

Arsenic-enriched groundwaters of India, Bangladesh and Taiwan--comparison of hydrochemical characteristics and mobility constraints

Arsenic (As) enrichment in groundwater has become a major global environmental disaster. Groundwater samples were collected from 64 sites located in the districts of 24-Parganas (S), and Nadia in West Bengal, India (Bhagirathi sub-basin), and 51 sites located in the districts of Comilla, Noakhali, Magura, Brahman baria, Laxmipur, Munshiganj, Faridpur and Jhenaida in Bangladesh (Padma-Meghna sub-basin). Groundwater samples were also collected from two As-affected areas (Chianan and Lanyang plains) of Taiwan (n = 26). The concentrations of major solutes in groundwater of the Padma-Meghna sub-basin are more variable than the Bhagirathi sub-basin, suggesting variations in the depositional and hydrological settings. Arsenic concentrations in groundwaters of the studied areas showed large variations, with mean As concentrations of 125 μg/L (range: 0.20 to 1,301 μg/L) in Bhagirathi sub-basin, 145 μg/L (range: 0.20 to 891 μg/L) in Padma-Meghna sub-basin, 209 μg/L (range: 1.3 to 575 μg/L) in Chianan plain, and 102 μg/L (range: 2.5 to 348 μg/L) in Lanyang plain groundwater. The concentrations of Fe, and Mn are also highly variable, and are mostly above the WHO-recommended guideline values and local (Indian and Bangladeshi) drinking water standard. Piper plot shows that groundwaters of both Bhagirathi and Padma-Meghna sub-basins are of Ca-HCO(3) type. The Chianan plain groundwaters are of Na-Cl type, suggesting seawater intrusion, whereas Lanyang plain groundwaters are mostly of Na-HCO(3) type. The study shows that reductive dissolution of Fe(III)-oxyhydroxides is the dominant geochemical process releasing As from sediment to groundwater in all studied areas.