Dietary exposure and biomarkers of arsenic in consumers of fish and shellfish from France

Seafood, especially fish, is considered as a major dietary source of arsenic (As). Seafood consumption is recommended for nutritional properties but contaminant exposure should be considered. The objectives were to assess As intake of frequent French seafood consumers and exposure via biomarkers. Consumptions of 996 high consumers (18 and over) of 4 coastal areas were assessed using a validated food frequency questionnaire. Seafood samples were collected according to a total diet study (TDS) sampling method and analyzed for total As, arsenite (AsIII), arsenate (AsV), arsenobetaïne (AsB), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The average As dietary exposure is 94.7 ± 67.5 μg/kg bw/week in females and 77.3 ± 54.6 μg/kg bw/week in males (p < 0.001) and the inorganic As dietary exposure is respectively 3.34 ± 2.06 μg/kg bw/week and 3.04 ± 1.86 μg/kg bw/week (p < 0.05).Urine samples were collected from 382 of the subjects. The average urinary As concentration is 94.8 ± 250 μg/g creatinine for females and 59.7 ± 81.8 μg/g for males (p < 0.001). Samples having an As concentration above 75 μg/g creatinine (n = 101) were analyzed for inorganic As (As(III), As(V), MMA(V) and DMA(V)) which was 24.6 ± 27.9 μg/g creatinine for males and 27.1 ±20.6 μg/g for females. Analyses do not show any correlation between dietary exposure and urinary As.These results show that biological results should be interpreted cautiously. Diet recording seems to be the best way to assess dietary As exposure. Seafood is a high source of As exposure but even among high consumers it is not the main source of toxic As. From a public health point of view these results should be interpreted carefully in the absence of international consensus on the health-based guidance value.     

High levels of inorganic arsenic in rice in areas where arsenic-contaminated water is used for irrigation and cooking

Rice is the staple food for the people of arsenic endemic South (S) and South-East (SE) Asian countries. In this region, arsenic contaminated groundwater has been used not only for drinking and cooking purposes but also for rice cultivation during dry season. Irrigation of arsenic-contaminated groundwater for rice cultivation has resulted high deposition of arsenic in topsoil and uptake in rice grain posing a serious threat to the sustainable agriculture in this region. In addition, cooking rice with arsenic-contaminated water also increases arsenic burden in cooked rice. Inorganic arsenic is the main species of S and SE Asian rice (80 to 91% of the total arsenic), and the concentration of this toxic species is increased in cooked rice from inorganic arsenic-rich cooking water. The people of Bangladesh and West Bengal (India), the arsenic hot spots in the world, eat an average of 450 g rice a day. Therefore, in addition to drinking water, dietary intake of arsenic from rice is supposed to be another potential source of exposure, and to be a new disaster for the population of S and SE Asian countries. Arsenic speciation in raw and cooked rice, its bioavailability and the possible health hazard of inorganic arsenic in rice for the population of S and SE Asia have been discussed in this review.     

Inorganic arsenic in cooked rice and vegetables from Bangladeshi households

Many Bangladeshi suffer from arsenic-related health concerns. Most mitigation activities focus on identifying contaminated wells and reducing the amount of arsenic ingested from well water. Food as a source of arsenic exposure has been recently documented. The objectives of this study were to measure the main types of arsenic in commonly consumed foods in Bangladesh and estimate the average daily intake (ADI) of arsenic from food and water. Total, organic and inorganic, arsenic were measured in drinking water and in cooked rice and vegetables from Bangladeshi households. The mean total arsenic level in 46 rice samples was 358 microg/kg (range: 46 to 1,110 microg/kg dry weight) and 333 microg/kg (range: 19 to 2,334 microg/kg dry weight) in 39 vegetable samples. Inorganic arsenic calculated as arsenite and arsenate made up 87% of the total arsenic measured in rice, and 96% of the total arsenic in vegetables. Total arsenic in water ranged from 200 to 500 microg/L. Using individual, self-reported data on daily consumption of rice and drinking water the total arsenic ADI was 1,176 microg (range: 419 to 2,053 microg), 14% attributable to inorganic arsenic in cooked rice. The ADI is a conservative estimate; vegetable arsenic was not included due to limitations in self-reported daily consumption amounts. Given the arsenic levels measured in food and water and consumption of these items, cooked rice and vegetables are a substantial exposure pathway for inorganic arsenic. Intervention strategies must consider all sources of dietary arsenic intake.     

Assessment of arsenic exposure from groundwater and rice in Bengal Delta Region, West Bengal, India

Arsenic (As) induced identifiable health outcomes are now spreading across Indian subcontinent with continuous discovery of high As concentrations in groundwater. This study deals with groundwater hydrochemistry vis-à-vis As exposure assessment among rural population in Chakdaha block, West Bengal, India. The water quality survey reveals that 96% of the tubewells exceed WHO guideline value (10 μg/L of As). The groundwaters are generally anoxic (−283 to −22 mV) with circum-neutral pH (6.3 to 7.8). The hydrochemistry is dominated by HCO₃⁻ (208 to 440 mg/L), Ca²⁺ (79 to 178 mg/L) and Mg²⁺ (17 to 45 mg/L) ions along with high concentrations of As_T (As total, below detection limit to 0.29 mg/L), Fe_T (Fe total, 1.2 to 16 mg/L), and Fe(II) (0.74 to 16 mg/L). The result demonstrates that Fe(II)-Fe(III) cycling is the dominant process for the release of As from aquifer sediments to groundwater (and vice versa), which is mainly controlled by the local biogeochemical conditions. The exposure scenario reveals that the consumption of groundwater and rice are the major pathways of As accumulation in human body, which is explained by the dietary habit of the surveyed population. Finally, regular awareness campaign is essential as part of the management and prevention of health outcomes.     

Assessment of in vivo bioaccessibility of arsenic in dietary rice by a mass balance approach

A pilot dietary experiment was conducted over 10 days to evaluate whether a simple yet often underutilized approach of constructing mass balance of arsenic metabolites can be used to assess in vivo bioaccessibility of arsenic in cooked rice. Two volunteers were involved in this study. The quantity of drinking water, food and urine samples, together with arsenic concentration and speciation of these samples was monitored to construct a mass balance of arsenic intake and excretion. In the first five days, the two volunteers on a wheat diet had an average arsenic daily intake of 15.4 ± 2.6 µg and 9.6 ± 0.7 µg, respectively. In the next five days, these volunteers switched to a rice diet, increasing the average arsenic daily intake to 36.4 ± 2.8 µg and 34.1 ± 7.7 µg, respectively. Daily excretion of urinary arsenic, mostly as dimethylarsenic acid (DMA), doubled from 9.8 ± 0.3 µg to 21.0 ± 3.0 µg, and from 6.5 ± 0.8 µg to 11.6 ± 4.5 µg, respectively. The percentage of ingested arsenic excreted in urine remained constant at ∼ 58% for one volunteer before and after the rice diet, and was ∼ 69% for another. Mass balance established during a controlled dietary experiment over 10 days is shown to be a useful approach to evaluate in vivo bioaccessibility and metabolism of arsenic uptake from diet and is applicable to study with more subjects.     

Health risk assessment on dietary exposure to polycyclic aromatic hydrocarbons (PAHs) in Taiyuan, China

Twenty-five kinds of seven categories of foods were sampled in December 2008 and the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were determined. The highest level of total PAHs was detected in pork (195.30 ng/g) whereas the lowest concentration was found in milk (8.73 ng/g). The median values of B[a]P equivalent (B[a]P_eq) daily exposure doses for children, adolescents, adults and seniors of male were estimated to be 392.42, 511.01, 571.56 and 532.56 ng/d, respectively, whereas those for the above population groups of female were found to be 355.16, 440.51, 487.64 and 444.85 ng/d, respectively. The incremental lifetime cancer risk (ILCR) values at the 22.1th, 26.1th, 12.7th, 24.9th, 22.7th, 27.0th, 12.9th, and 25.5th percentiles for male children, male adolescents, male adults, male seniors, female children, female adolescents, female adults and female seniors, respectively, were larger than 10^− 6, indicating high potential carcinogenic risk, and were larger than 10^− 4 at the 74.5th, 78.7th, 60.6th, 77.4th, 75.3th, 79.5th, 60.8th and 77.9th percentiles for the above groups, respectively, which implied significant cancer risk. Sensitivity analysis found that the two variables of oral cancer slope factor of benzo(a) pyrene (SF) and the daily dietary PAH exposure level (ED) had the greater impact than that of body weight (BW) on the ILCR.     

Influence of traditional agricultural practices on mobilization of arsenic from sediments to groundwater in Bengal delta

In the wake of the idea that surface derived dissolved organic carbon (DOC) plays an important role in the mobilization of arsenic (As) from sediments to groundwater and may provide a vital tool in understanding the mechanism of As contamination (mobilization/fixation) in Bengal delta; a study has been carried out. Agricultural fields that mainly cultivate rice (paddy fields) leave significantly large quantities of organic matter/organic carbon on the surface of Bengal delta which during monsoon starts decomposing and produces DOC. The DOC thus produced percolates down with rain water and mobilizes As from the sediments. Investigations on sediment samples collected from a paddy field clearly indicate that As coming on to the surface along with the irrigation water accumulates itself in the top few meters of sediment profile. The column experiments carried out on a 9 m deep sediment profile demonstrates that DOC has a strong potential to mobilize As from the paddy fields and the water recharging the aquifer through such agricultural fields contain As well above the WHO limit thus contaminating the shallow groundwater. Experiment also demonstrates that decay of organic matter induces reducing condition in the sediments. Progressively increasing reducing conditions not only prevent the adsorption of As on mineral surfaces but also cause mobilization of previously sorbed arsenic. There seems to be a cyclic pattern where As from deeper levels comes to the surface with irrigational water, accumulates itself in the sediments, and ultimately moves down to the shallow groundwater. The extensive and continual exploitation of intermediate/deep groundwater accelerates this cyclic process and helps in the movement of shallow contaminated groundwater to the deeper levels.     

Prevalence of skin lesions and exposure to arsenic in drinking water in Iran

Prevalence of skin lesions was investigated among 752 participants in eight villages in Kurdistan province in Iran with emphasis on total lifetime intake of arsenic from drinking water (TLIA). The participants were selected from eight villages with different exposure levels using a cluster-sampling technique. TLIA was calculated for each individual taking into account the type of water supply and their mean annual arsenic concentration. The study showed that 49 persons (6.5%) were suffering from hyperkeratosis and 20 persons (2.7%) from hyperpigmentation. The correlation between hyperkeratosis and hyperpigmentation was significant (R=0.325, p<0.01). Using the logistic regression model it was found that the relationship between TLIA and hyperkeratosis (OR=1.14, 95% CI=1.039-1.249), and hyperpigmentation (OR=1.254, 95% CI=1.112-1.416) was also significant. In conclusion, TLIA can be applied as a reliable indicator for the assessment of exposure.     

Dominance of dietary intake of metals in marine elasmobranch and teleost fish

Metal accumulation in marine fish is a global public health concern, because the consumption of seafood provides the largest dose of many toxic metals to humans. While water quality criteria often rely on aqueous exposures of metals to fish in developing safety guidelines, it is increasingly recognized that marine fish obtain an important fraction of their metal body burden from their diet. Using experimental data, we modeled the accumulation of six metals (Am, Cd, Cs, Co, Mn, Zn) from diet and from the aqueous phase in two marine fish species, the teleost Psetta maxima and elasmobranch Scyliorhinus canicula. We estimated steady-state metal concentrations and calculated the relative contributions of dietary and aqueous intake in both species. For both species > 60% and often > 90% of Mn, Cd, and Zn derives from dietary intake in these species, even at the lowest ingestion rates reported for these fish. At low ingestion rates, Am was obtained predominantly from the aqueous phase and Cs varied considerably depending on prey selection. Inter-specific differences were noted, especially in Co uptake. Model predictions of steady-state tissue metal concentrations are within the range of field measurements for these species. Our findings underscore the importance of including dietary exposure in understanding metal accumulation in marine fish.     

Well-head arsenic removal units in remote villages of Indian subcontinent: field results and performance evaluation

Since 1997, over 135 well-head arsenic removal units have been installed in remote villages in the Indian state of West Bengal bordering Bangladesh. Every component of the arsenic removal treatment system including activated alumina sorbent is procured indigenously. Each unit serves approximately 200-300 households and contains about 100 L of activated alumina. No chemical addition, pH adjustment or electricity is required for operating these units. The arsenic concentration in the influent varies from around 100 μg/L to greater than 500 μg/L. In the treated water, arsenic concentration is consistently below 50 μg/L. The units are capable of removing both arsenites and arsenates from the contaminated groundwater for several months, often exceeding 10,000 bed volumes. In the top portion of the column, the dissolved iron present in ground water is oxidized by atmospheric oxygen into hydrated Fe(III) oxides or HFO particles which in turn selectively bind both As(III) and As(V). Upon exhaustion, these units are regenerated by caustic soda solution followed by acid wash. The arsenic-laden spent regenerant is converted into a small volume sludge (less than 500 g) and contained over a coarse sand filter in the same premise requiring no disposal. Many units have been operating for several years without any significant operational difficulty. The treated water is used for drinking and cooking. Most importantly, the villagers are responsible for the day to day operation and the upkeep of the units.     

Influence of operating parameters on the arsenic removal by nanofiltration

Arsenic contamination of surface and groundwater is a worldwide problem in a large number of Countries (Bangladesh, Argentina, Italy, USA, New Zealand, etc.). In many contaminated areas a continuous investigation of the available arsenic removal technologies is essential to develop economical and effective methods for removing arsenic in order to meet the new Maximum Contaminant Level (MCL) standard (10 μg/l) recommended by the World Health Organization (WHO).In this work the removal of pentavalent arsenic from synthetic water was studied on laboratory scale by using two commercial nanofiltration (NF) spiral-wound membrane modules (N30F by Microdyn-Nadir and NF90 by Dow Chemical). The influence of main operating parameters such as feed concentration, pH, pressure and temperature on the As rejection and permeate flux of both membranes, was investigated. An increase of pH and a decrease of operating temperature and As feed concentration led to higher As removal for both membranes, whereas higher transmembrane pressure (TMP) values slightly reduced the removal achievable with the N30F membrane. In both cases, the permeate flux increased with temperature and pressure and reached its maximum value at a pH of around 8.Among the parameters affecting the As rejection, feed concentration plays a key role for the production of a permeate stream respecting the limits imposed by WHO.     

Evolution of community-based arsenic removal systems in remote villages in West Bengal, India: Assessment of decade-long operation

In Bangladesh and the neighboring state of West Bengal, India, over 100 million people are affected by widespread arsenic poisoning through drinking water drawn from underground sources containing arsenic at concentrations well above the permissible limit of 50 μg/L. The health effects caused by arsenic poisoning in this area is as catastrophic as any other natural calamity that occurred throughout the world in recent times. Since 1997, over 200 community level arsenic removal units have been installed in Indian subcontinent through collaboration between Bengal Engineering and Science University (BESU), India and Lehigh University, USA. Approximately 200,000 villagers collect arsenic-safe potable water from these units on a daily basis. The treated water is also safe for drinking with regard to its total dissolved solids, hardness, iron and manganese content. The units use regenerable arsenic-selective adsorbents. Regular maintenance and upkeep of the units is administered by the villagers through formation of villagers’ water committee. The villagers contribute towards the cost of operation through collection of a small water tariff. Upon exhaustion, the adsorbents are regenerated in a central facility by a few trained villagers. The process of regeneration reduces the volume of disposable arsenic-laden solids by nearly two orders of magnitude and allows for the reuse of the adsorbent material. Finally, the arsenic-laden solids are contained on well-aerated coarse sand filters with minimum arsenic leaching. This disposal technique is scientifically more appropriate than dumping arsenic-loaded adsorbents in the reducing environment of landfills as currently practiced in developed countries including the United States. The design of the units underwent several modifications over last ten years to enhance the efficiency in terms of arsenic removal, ease of maintenance and ecologically safe containment and disposal of treatment residuals. The continued safe operation of these units has amply demonstrated that use of regenerable arsenic-selective adsorbents is quite viable in remote locations. The technology and associated socio-economic management of the units have matured over the years, generating promise for rapid replication in other severely arsenic-affected countries in Southeast Asia.     

Levels and patterns of Persistent Organic Pollutants (POPS) in selected food items from Northwest Russia (1998-2002) and implications for dietary exposure

Residues of persistent organic pollutants (POPs) were analysed in 70 selected food items from Northwest Russia in 1998-2002. Levels of PCBs ranged from 0.2 to 16 ng/g wet weight (ww) in dairy products and fats, 0.2 to 23 ng/g ww in meat products, 0.5 to 16 ng/g ww in eggs and 0.3 to 30 ng/g ww in fish. High levels of DDT (16 ng/g ww) were found in locally produced butter from Kola Peninsula, in pork fat from Arkhangels region (10 to 130 ng/g ww) and in some fish samples from White Sea and Kargopol region (17 and 30 ng/g ww). Findings of low DDE/DDT ratios in many of the studied food items indicated recent contamination to DDTs. Mean levels of sum TEQs_WHO1998 of dioxin-like mono-ortho PCBs: PCBs 105, 118, 156 and 157 (∑ mo-PCBs-TEQs_WHO1998) were highest in dairy products, chicken eggs and fish, with levels of 0.292, 0.245 and 0.254 pg/g ww, respectively. The estimated daily intake (EDI) for ∑ mo-PCBs-TEQs_WHO1998 was 0.74 pg/kgbw/day and in the same range as in Sweden and Denmark. Fish, dairy products, eggs and meat were the main contributors to the EDI of ∑ mo-PCBs-TEQs_WHO1998. The EDIs of DDTs, HCHs and HCB were several times higher than in Sweden and Denmark. Consumption of meat and poultry were important sources for intake of DDTs and HCHs, respectively. Contamination of animal feed and agricultural practice were assumed the most important causes for the results in the present study. However, increased control on maximum residue levels in food and feed may have resulted in large changes on levels and patterns of POPs in food in the studied areas.     

Household air pollution and personal exposure to nitrated and oxygenated polycyclic aromatics (PAHs) in rural households: Influence of household cooking energies

Residential solid fuels are widely consumed in rural China, contributing to severe household air pollution for many products of incomplete combustion, such as polycyclic aromatic hydrocarbons (PAHs) and their polar derivatives. In this study, concentrations of nitrated and oxygenated PAH derivatives (nPAHs and oPAHs) for household and personal air were measured and analyzed for influencing factors like smoking and cooking energy type. Concentrations of nPAHs and oPAHs in kitchens were higher than those in living rooms and in outdoor air. Exposure levels measured by personal samplers were lower than levels in indoor air, but higher than outdoor air levels. With increasing molecular weight, individual compounds tended to be more commonly partitioned to particulate matter (PM); moreover, higher molecular weight nPAHs and oPAHs were preferentially found in finer particles, suggesting a potential for increased health risks. Smoking behavior raised the concentrations of nPAHs and oPAHs in personal air significantly. People who cooked food also had higher personal exposures. Cooking and smoking have a significant interaction effect on personal exposure. Concentrations in kitchens and personal exposure to nPAHs and oPAHs for households using wood and peat were significantly higher than for those using electricity and liquid petroleum gas (LPG).     

Arsenic levels in wipe samples collected from play structures constructed with CCA-treated wood: Impact on exposure estimates

Lumber treated with chromated copper arsenate (CCA) has been used in residential outdoor wood structures and playgrounds. The U.S. EPA has conducted a probabilistic assessment of children's exposure to arsenic from CCA-treated structures using the Stochastic Human Exposure and Dose Simulation model for the wood preservative scenario (SHEDS-Wood). The EPA assessment relied on data from an experimental study using adult volunteers and designed to measure arsenic in maximum hand and wipe loadings. Analyses using arsenic handloading data from a study of children playing on CCA-treated play structures in Edmonton, Canada, indicate that the maximum handloading values significantly overestimate the exposure that occurs during actual play. The objective of our paper is to assess whether the dislodgeable arsenic residues from structures in the Edmonton study are comparable to those observed in other studies and whether they support the conclusion that the values derived by EPA using modeled maximum loading values overestimate hand exposures. We compared dislodgeable arsenic residue data from structures in the playgrounds in the Edmonton study to levels observed in studies used in EPA's assessment. Our analysis showed that the dislodgeable arsenic levels in the Edmonton playground structures are similar to those in the studies used by EPA. Hence, the exposure estimates derived using the handloading data from children playing on CCA-treated structures are more representative of children's actual exposures than the overestimates derived by EPA using modeled maximum values. Handloading data from children playing on CCA-treated structures should be used to reduce the uncertainty of modeled estimates derived using the SHEDS-Wood model.     

pH-dependent effect of zinc on arsenic adsorption to magnetite nanoparticles

The effect of Zn²⁺ on both the kinetic and equilibrium aspects of arsenic adsorption to magnetite nanoparticles was investigated at pH 4.5-8.0. At pH 8.0, adsorption of both arsenate and arsenite to magnetite nanoparticles was significantly enhanced by the presence of small amount of Zn²⁺ in the solution. With less than 3 mg/L of Zn²⁺ added to the arsenic solution prior to the addition of magnetite nanoparticles, the percentage of arsenic removal by magnetite nanoparticles increased from 66% to over 99% for arsenate, and from 80% to 95% for arsenite from an initial concentration of ∼100 μg/L As at pH 8.0. Adsorption rate also increased significantly in the presence of Zn²⁺. The adsorption-enhancement effect of Zn²⁺ was not observed at pH 4.5-6.0, nor with ZnO nanoparticles, nor with surface-coated Zn-magnetite nanoparticles. The enhanced arsenic adsorption in the presence of Zn²⁺ cannot be due to reduced negative charge of the magnetite nanoparticles surface by zinc adsorption. Other cations, such as Ca²⁺ and Ag⁺, failed to enhance arsenic adsorption. Several potential mechanisms that could have caused the enhanced adsorption of arsenic have been tested and ruled out. Formation of a ternary surface complex by zinc, arsenic and magnetite nanoparticles is a possible mechanism controlling the observed zinc effect. Zinc-facilitated adsorption provides further advantage for magnetite nanoparticle-enhanced arsenic removal over conventional treatment approaches.

Synopsis

Arsenic adsorption to magnetite nanoparticles at neutral or slightly basic pH can be significantly enhanced with trace amount of Zn²⁺ due to the formation of a ternary complex.     

Household air pollution and personal exposure risk of polycyclic aromatic hydrocarbons among rural residents in Shanxi,China

Polycyclic aromatic hydrocarbons (PAHs) are a group of pollutants of widespread concerns. Gaseous and size‐segregated particulate‐phase PAHs were collected in indoor and outdoor air in rural households. Personal exposure was measured and compared to the ingestion exposure. The average concentrations of 28 parent PAHs and benzo(a)pyrene (BaP) were 9000 ± 8390 and 131 ± 236 ng/m³ for kitchen, 2590 ± 2270 and 43 ± 95 ng/m³ for living room, and 2800 ± 3890 and 1.6 ± 0.7 ng/m³ for outdoor air, respectively. The mass percent of high molecular weight (HMW) compounds with 5–6 rings contributed 1.3% to total 28 parent PAHs. Relatively higher fractions of HMW PAHs were found in indoor air compared to outdoor air. Majorities of particle‐bound PAHs were found in the finest PM_0.25, and the highest levels of fine PM_0.25‐bound PAHs were in the kitchen using peat and wood as energy sources. The 24‐h personal PAH exposure concentration was 2100 ± 1300 ng/m³. Considering energies, exposures to those using wood were the highest. The PAH inhalation exposure comprised up to about 30% in total PAH exposure through food ingestion and inhalation, and the population attributable fraction (PAF) for lung cancer in the region was 0.85%. The risks for inhaled and ingested intakes of PAHs were 1.0 × 10^?5 and 1.1 × 10^?5, respectively.     

The magnitude of arsenic contamination in groundwater and its health effects to the inhabitants of the Jalangi--one of the 85 arsenic affected blocks in West Bengal, India

To better understand the magnitude of arsenic contamination in groundwater and its effects on human beings, a detailed study was carried out in Jalangi, one of the 85 arsenic affected blocks in West Bengal, India. Jalangi block is approximately 122 km2 in size and has a population of 215538. Of the 1916 water samples analyzed (about 31% of the total hand tubewells) from the Jalangi block, 77.8% were found to have arsenic above 10 microg l(-1) [the World Health Organization (WHO)-recommended level of arsenic in drinking water], 51% had arsenic above 50 microg l(-1) (the Indian standard of permissible limit of arsenic in drinking water) and 17% had arsenic at above 300 microg l(-1) (the concentration predicting overt arsenical skin lesions). From our preliminary medical screening, 1488 of the 7221 people examined in the 44 villages of Jalangi block exhibit definite arsenical skin lesions. An estimation of probable population that may suffer from arsenical skin lesions and cancer in the Jalangi block has been evaluated comparing along with international data. A total of 1600 biologic samples including hair, nail and urine have been analyzed from the affected villages of Jalangi block and on an average 88% of the biologic samples contain arsenic above the normal level. Thus, a vast population of the block may have arsenic body burden. Cases of Bowen's disease and cancer have been identified among adults who also show arsenical skin lesions and children in this block are also seriously affected. Obstetric examinations were also carried out in this block.     

Implications of organic matter on arsenic mobilization into groundwater: Evidence from northwestern (Chapai-Nawabganj), central (Manikganj) and southeastern (Chandpur) Bangladesh

Boreholes (50 m depth) and piezometers (50 m depth) were drilled and installed for collecting As-rich sediments and groundwater in the Ganges, Brahmaputra, and Meghna flood plains for geochemical analyses. Forty-one groundwater samples were collected from the three areas for the analyses of cations (Ca²⁺, Mg²⁺, K⁺, Na⁺), anions (Cl⁻, NO₃⁻, SO₄²⁻), total organic carbon (TOC), and trace elements (As, Mn, Fe, Sr, Se, Ni, Co, Cu, Mo, Sb, Pb). X-ray powder diffraction (XRD) and X-ray fluorescence (XRF) were performed to characterize the major mineral and chemical contents of aquifer sediments. In all three study areas, results of XRF analysis clearly show that fine-grained sediments contain higher amounts of trace element because of their high surface area for adsorption. Relative fluorescent intensity of humic substances in groundwater samples ranges from 30 to 102 (mean 58 ± 20, n = 20), 54-195 (mean 105 ± 48, n = 10), and 27-243 (mean 79 ± 71, n = 11) in the Ganges, Brahmaputra and Meghna flood plains, respectively. Arsenic concentration in groundwater (20-50 m of depth) ranges from 3 to 315 μg/L (mean 62.4 ± 93.1 μg/L, n = 20), 16.4-73.7 μg/L (mean 28.5 ± 22.4 μg/L, n = 10) and 4.6-215.4 μg/L (mean 30.7 ± 62.1 μg/L, n = 11) in the Ganges, Brahmaputra and Meghna flood plains, respectively. Specific ultra violet adsorption (SUVA) values (less than 3 m⁻¹ mg⁻¹ L) indicate that the groundwater in the Ganges flood plain has relatively low percentage of aromatic organic carbon compared to those in the Brahmaputra and Meghna flood plains. Arsenic content in sediments ranges from 1 to 11 mg/kg (mean 3.5 ± 2.7 mg/kg, n = 17) in the three flood plains. Total organic carbon content is 0.5-3.7 g/kg (mean 1.9 ± 1.1 g/kg) in the Ganges flood plain, 0.5-2.1 g/kg (mean: 1.1 ± 0.7 g/kg) in the Brahmaputra flood plain and 0.3-4.4 g/kg (mean 1.9 ± 1.9 g/kg) in the Meghna flood plain. Arsenic is positively correlated with TOC (R² = 0.50, 0.87, and 0.85) in sediments from the three areas. Fourier transform infrared (FT-IR) analysis of the sediments revealed that the functional groups of humic substances in three areas include amines, phenol, alkanes, and aromatic carbon. Arsenic and Fe speciation in sediments were determined using XANES and the results imply that As(V) and Fe(III) are the dominant species in most sediments. The results also imply that As (V) and Fe (III) in most of the sediment samples of the three areas are the dominant species. X-ray absorption fine structure (EXAFS) analysis shows that FeOOH is the main carrier of As in the sediments of three areas. In sediments, As is well correlated with Fe and Mn. However, there is no such correlation observed between As and Fe as well as As and Mn in groundwater, implying that mobilizations of Fe, Mn, and As are decoupled or their concentrations in groundwater have been affected by other geochemical processes following reductive dissolution of Fe or Mn-hydroxides. For example, dissolved Fe and Mn levels may be affected by precipitation of Fe- and Mn-carbonate minerals such as siderite, while liberated As remains in groundwater. The groundwaters of the Brahmaputra and Meghna flood plains contain higher humic substances in relative fluorescence intensity (or fluorescence index) and lower redox potential compared to the groundwater of Ganges flood plain. This leads to the release of arsenic and iron to groundwater of these three plains in considerable amounts, but their concentrations are distributed in spatial variations.     

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.