Impact of sedimentary arsenic through irrigated groundwater on soil, plant, crops and human continuum from Bengal delta: Special reference to raw and cooked rice

An extensive review of arsenic dynamics and its distribution in soil-aqueous-rice plant systems in south and Southeast Asia with bibliographic and meta-data analysis

Millions of people worldwide are affected by arsenic (As) contamination, particularly in South and Southeast Asian countries, where large-scale dependence on the usage of As-contaminated groundwater in drinking and irrigation is a familiar practice. Rice (Oryza sativa) cultivation is commonly done in South and Southeast Asian countries as a preferable crop which takes up more As than any other cereals. The present article has performed a scientific meta-data analysis and extensive bibliometric analysis to demonstrate the research trend in global rice As contamination scenario in the timeframe of 1980-2023. This study identified that China contributes most with the maximum number of publications followed by India, USA, UK and Bangladesh. The two words 'arsenic' and 'rice' have been identified as the most dominant keywords used by the authors, found through co-occurrence cluster analysis with author keyword association study. The comprehensive perceptive attained about the factors affecting As load in plant tissue and the nature of the micro-environment augment the contamination of rice cultivars in the region. This extensive review analyses soil parameters through meta-data regression assessment that influence and control As dynamics in soil with its further loading into rice grains and presents that As content and OM are inversely related and slightly correlated to the pH increment of the soil. Additionally, irrigation and water management practices have been found as a potential modulator of soil As concentration and bioavailability, presented through a linear fit with 95% confidence interval method.

Arsenic uptake and accumulation in bean and lettuce plants at different developmental stages

The pattern of arsenic (As) uptake at different developmental stages in plants and its consequent influence on the growth of plants was investigated in bean and lettuce. Further, the human health risk from the consumption of these As-laced vegetables was determined. The irrigation water was contaminated with As at concentrations of 0.1, 0.25, and 0.5 mg/L. The As concentration in the plant parts (root, stem, leaves, and flower/fruit) was determined in bean at the young, flowering, and fruiting stages and lettuce at the young and mature stages. At the different growth stages, As had an impact on the biomass of bean and lettuce plant parts, but none of the biomass changes were significant (p>0.05). The increase in As concentration of the irrigation water elevated the As concentration of plant parts of both plants at all growth stages, with the exception of the bean fruit. The As concentration in the developmental stages was in the order: lettuce (young>mature) and bean (fruiting>young>flowering). In lettuce, the transfer factor was higher at the young stage (0.09-0.19, in the control and 0.1 mg/L As treatment), while in bean, it was highest at the flowering stage (0.09-0.41, in all treatments). In the edible part, lettuce possessed substantially elevated As concentrations (0.30, 0.61, and 1.21 mg/kg DW) compared to bean (0.008, 0.005, and 0.022 mg/kg DW) at As treatments of 0.1, 0.25, and 0.5 mg/L, respectively, and posed significant health risks at all applied As concentrations.

Evaluating the efficacy and feasibility of post harvest methods for arsenic removal from rice grain and reduction of arsenic induced cancer risk from rice-based diet

Food-chain arsenic (As) contamination is a severe environmental and health problem worldwide, and its intake through rice affects billions of people. In this review, we have summarized the post harvest As removal methods from rice and their efficacy and feasibility. Rice grain subspecies (indica and japonica), size (short, medium and long), type (husked, parboiled or polished), soaking time, temperature and rice to water ratio (r/w) during washing and cooking are the major factors that affect the removal of total arsenic (tAs) from rice grain. The reduction in tAs was greater in japonica than indica rice and was directly proportional to As in husked rice. For the removal of As, a low water volume (1:2 r/w) was more effective during washing due to friction between rice grains, while high water (≥4 times water) during cooking was more effective. Up to 80 % As was removed by cooking in 1:10 (rice: water). Soaking rice in edible acids such as vinegar, acetic and ascorbic acid was not effective, except citric acid, which removes tAs up to 63 %. Human-health risk assessment showed that these post harvest and cooking methods reduce the non-carcinogenic and incremental lifetime cancer risk by up to 5-fold, as calculated on the basis of bioaccessible inorganic As. These post harvest methods also remove nutrient elements and vitamins. The recommended dietary intake (RDI) of Zn and Cu was particularly affected (up to 40 and 83 %). The levels of P, Mo, Mn and Co were still sufficient to meet the RDI through the rice-based diet, while rice is already poor in the RDI of Ca, K, Fe and Se, and their levels were further reduced by 0.22-44 %. In conclusion, these post harvest and cooking methods may significantly reduce As induced health risks; however, other dietary sources of nutrients need to be carefully evaluated and supplemented.

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).

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

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

Rapid detection of ultratrace urinary arsenic by direct sampling microplasma vaporization based on silicon nitride

At present, immediate monitoring urinary arsenic is still a challenge for treating arsenic poisoning patients. Thus, a fast, reliable and accurate analytical approach is indispensable to monitor ultratrace arsenic in urine sample for health warning. In this work, a silicon nitride (SN) rod was first integrally utilized as a sample carrier for ≤50 μL urinary aliquot, an electric heater for removing water and ashing sample as well as a high voltage electrode for dielectric barrier discharge vaporization (DBDV). The direct analytical method of arsenic in urine without sample digestion was thus developed using atomic fluorescence spectrometer (AFS) as a model detector. After 4 V electrically heating the SN rod for 60 s, urine sample was dehydrated and ashed outside; then, DBD was exerted under 0.8 A with 0.8 L/min H₂ + Ar (1:9, v:v) for 20 s to vaporize arsenic analyte from the SN rod. After optimization, 0.014 μg/L arsenic detection limit (LOD) was reached with favorable analytical precision (RSD <5%) and accuracy (91-110% recoveries) for real sample analysis. As a result, the whole analysis process only consumes <3 min to exclude complicated sample preparation; furthermore, the designed DBDV system only occupies 25 W and <2 kg, which renders a miniature sampling component to hyphenate with a miniature detector to detect arsenic. Thus, this direct sampling DBDV method extremely fulfills the fast, sensitive and precise detection of ultratrace arsenic in urine sample.

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

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

Effect of foliage applied chitosan-based silicon nanoparticles on arsenic uptake and translocation in rice (Oryza sativa L.)

In this study, chitosan-based silicon nanoparticles (Chsi-NPs) are prepared that primarily consists of C (57.9%), O (31.3%), N (5.6%), and Si (3.5%) and are 10-180 nm in size. We then explore the effect on the foliage applied on rice planted on soil contaminated with 104 mg·kg^-1 arsenic (As); low (3 mg·L^-1)and high (15 mg·L^-1) doses of the foliar Chsi-NPs are administered during the rice grain filling stage. The results showed that the higher dose foliar Chsi-NPs treatment reduced the As concentration in the grain by 61.2% but increased As concentration in the leaves by 47.1% compared to the control treatment. The foliar spraying of the Chsi-NPs inhibited As transport to the grain by facilitating the attachment of As to the cell wall, with higher doses of the foliar Chsi-NPs treatment increased by 8.7%. The foliar spraying of Chsi-NPs increased the malondialdehyde levels by 18.4%, the catalase activity by 49.0%, and the glutathione activity by 99.0%. These results indicated that the foliar Chsi-NPs application was effective for alleviating As toxicity and accumulation in rice. This study provides a novel method for effectively alleviating As accumulation in rice.

Arsenic contamination, impact and mitigation strategies in rice agro-environment: An inclusive insight

Arsenic (As) contamination and its adverse consequences on rice agroecosystem are well known. Rice has the credit to feed more than 50% of the world population but concurrently, rice accumulates a substantial amount of As, thereby compromising food security. The gravity of the situation lays in the fact that the population in theAs uncontaminated areas may be accidentally exposed to toxic levels of As from rice consumption. In this review, we are trying to summarize the documents on the impact of As contamination and phytotoxicity in past two decades. The unique feature of this attempt is wide spectrum coverages of topics, and that makes it truly an interdisciplinary review. Aprat from the behaviour of As in rice field soil, we have documented the cellular and molecular response of rice plant upon exposure to As. The potential of various mitigation strategies with particular emphasis on using biochar, seed priming technology, irrigation management, transgenic variety development and other agronomic methods have been critically explored. The review attempts to give a comprehensive and multidiciplinary insight into the behaviour of As in Paddy -Water - Soil - Plate prospective from molecular to post-harvest phase. From the comprehensive literature review, we may conclude that considerable emphasis on rice grain, nutritional and anti-nutritional components, and grain quality traits under arsenic stress condition is yet to be given. Besides these, some emerging mitigation options like seed priming technology, adoption of nanotechnological strategies, applications of biochar should be fortified in large scale without interfering with the proper use of biodiversity.

Novel Dielectric Barrier Discharge Trap for Arsenic Introduced by Electrothermal Vaporization: Possible Mechanism and Its Application

In this work, a novel integrated dielectric barrier discharge (IDBD) reactor coupled to an electrothermal vaporizer (ETV) was established for arsenic determination. It is for the first time gas-phase enrichment (GPE) was fulfilled based on the hyphenation of ETV and DBD. The mechanisms of evolution of arsenic atomic and molecular species during vaporization, transportation, trapping, and release processes were investigated via X-ray photoelectron spectroscopy (XPS) and other approaches. Tentative mechanisms were deduced as follows: the newly designed DBD atomizer (DBDA) tube upstream to the air inlet fulfills the atomization of arsenic nanoparticles in vaporized aerosol, leading to free arsenic atoms that are indispensable for forming arsenic oxides; the DBD trap (DBDT) tube traps arsenic oxides under an O₂-domininating atmosphere and then releases arsenic atoms under H₂-dominating atmospheres. In essence, this process is a physical-chemical process rather than an electrostatic particle deposition. Such a trap and release sequence separates matrix interference and enhances analytical sensitivity. Under the optimized conditions, the method detection limit (LOD) was 0.04 mg/kg and the relative standard deviations (RSDs) were within 6% for As standard solution and real seafood samples, indicating adequate analytical sensitivity and precision. The mean spiked recoveries for laver, kelp, and Undaria pinnatifida samples were 95-110%, and the results of the certified reference materials (CRMs) were consistent with certified values. This ETV-DBD preconcentration scheme is easy and green and has low cost for As analysis in seafood samples. DBD was proved a novel ETV transportation enhancement and preconcentration technique for arsenic, revealing its potential in rapid arsenic analysis based on direct solid sampling ETV instrumentation.

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.

Effect of arsenic-contaminated irrigation water on growth and elemental composition of tomato and cabbage cultivated in three different soils, and related health risk assessment

This study was carried out to determine the effect of arsenic on tomato and cabbage cultivated in sand, sandy silt, and silt soil, and irrigated with water containing arsenic at concentrations 0.05 and 0.2 mg/L. Increasing arsenic in irrigation water did not affect the photosynthetic machinery. The chlorophyll content index increased in case of all soils and was dependent on the soil nitrogen, phosphorous, and plant biomass. Arsenic concentrations of 0.05 and 0.2 mg/L did not display any phytotoxic symptoms other than reduction in biomass in some cases. In cabbage, arsenic treatment of 0.2 mg/L increased the overall plant biomass production, while in tomato there was a decrease in aerial part and fruit biomass. The biomass production of both plants treated with different concentrations of arsenic, in the three soils was in the following order: silt > sand > sandy silt. Increase of arsenic in the irrigation water resulted in increase in arsenic concentration in the root and aerial part of both plants, at the same cultivation parameters. But tomato fruits displayed a decrease in arsenic accumulation with higher arsenic treatment. In both plants, the arsenic concentration in the plant parts changed in the following order: root > aerial part > fruit. Cabbage accumulated approximately twenty-fold more arsenic in the edible part (0.10-0.25 mg/kg DW) as compared to tomato (0.006-0.011 mg/kg DW) and displayed a good correlation with soil extractable arsenic. When cabbage was cultivated in three different soils applying the same irrigation water, it accumulated arsenic in the following order: sand > sandy silt > silt (p < 0.001 at 0.05 mg/L and p < 0.01 at 0.2 mg/L arsenic treatment). In tomato, the difference in arsenic accumulation among different soil types was highly significant (p < 0.001) but the accumulation pattern varied with the arsenic treatment applied. Sandy soil with the lowest total soil arsenic (4.32 mg/kg) resulted in the highest arsenic concentration in both plants. Among all soils and plants, the transfer factors and bioaccumulation factors were higher in sandy soil, and in cabbage. The estimated daily intake and hazard quotient values for arsenic were lower than 1 in all cases, implying no non-cancerous health risks at the arsenic concentrations applied in our study. Among nutrients only P showed a slight decline with increasing arsenic concentration while all other elements (Mg, K, Ca, S, Si, Fe, Mn, Cu, Zn) did not display any significant changes.

Impact of Water Regimes and Amendments on Inorganic Arsenic Exposure to Rice

Rice-based diet faces an important public health concern due to arsenic (As) accumulation in rice grain, which is toxic to humans. Rice crops are prone to assimilate As due to continuously flooded cultivation. In this study, the objective was to determine how water regimes (flooded and aerobic) in rice cultivation impact total As and inorganic As speciation in rice on the basis of a field-scale trial in the post-monsoon season. Iron and silicon with NPK/organic manure were amended in each regime. We hypothesised that aerobic practice receiving amendments would reduce As uptake in rice grain with a subsequent decrease in accumulation of inorganic As species relative to flooded conditions (control). Continuously flooded conditions enhanced soil As availability by 32% compared to aerobic conditions. Under aerobic conditions, total As concentrations in rice decreased by 62% compared to flooded conditions. Speciation analyses revealed that aerobic conditions significantly reduced (p < 0.05) arsenite (68%) and arsenate (61%) accumulation in rice grains. Iron and silicon exhibited significant impact on reducing arsenate and arsenite uptake in rice, respectively. The study indicates that aerobic rice cultivation with minimum use of irrigation water can lead to lower risk of inorganic As exposure to rice relative to flooded practice.

Heavy metal(loid)s contamination and health risk assessment of soil-rice system in rural and peri-urban areas of lower brahmaputra valley, northeast India

The soil-rice system in rural and peri-urban areas of the lower Brahmaputra valley, northeast India was investigated for heavy metal(loid)s using Nemerow's pollution index (PI_N) and potential ecological risk index (RI). Potential health risk due to rice consumption grown in the region was assessed in terms of carcinogenic and non-carcinogenic risks. Around 95% of the soil showed acidic nature that ranged from weakly acidic to strongly acidic soil. In terms of PI_N, 27.3% of the sampling sites were heavily polluted (PI_N≥3), 34.8% moderately, and 37.9% were slightly polluted. The Pb concentration was comparably higher in 57.1% of the rice grain samples and the mean As level (0.17 mg kg^-1) was close to the WHO limit. The non-carcinogenic risk in terms of hazard quotient (HQ) was high primarily due to As (HQ > 1), whereas other metals had limited contribution (HQ < 1). The carcinogenic risk based on total cancer risk (TCR) values for adults and children ranged between 0.0039 - 0.019 and 0.0043-0.0211, respectively, exceeding the maximum acceptable level of 1 × 10^-4. Among the rice varieties, for non-carcinogenic risks, the maximum hazard index (HI) was noticed for Bahadur and the minimum for Ranjit. Whereas for carcinogenic risks, the maximum TCR was observed for Mahsuri and the minimum for Moynagiri.

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.

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).

Paddy soil geochemistry, uptake of trace elements by rice grains (Oryza sativa) and resulting health risks in the Mekong River Delta, Vietnam

Soil geochemistry and phytoavailable trace elements were investigated in 80 paddy soil samples and corresponding rice grains from the Mekong River Delta in Vietnam. Soil parameters like Fe-, Al-, and Mn-phases, organic matter, and pH-value determine element concentrations in soil and affect their transfer into rice grains. Arsenic exceeded the allowed limit for Vietnamese agricultural soils in 11% of the samples, presumably caused by natural processes. Lead surpassed the limit in one soil sample. Other toxic elements were close to their natural concentrations and far below allowable limits for agricultural soil. There was no clear correlation of trace element concentrations in soils with those in corresponding grains, even if the different soil parameters and the large pH-range between 3.7 and 6.8 were considered. To assess health risks of critical elements in rice, the thresholds of tolerable upper intake level for total food and drinking water (UL) and of permissible maximum concentration (MC) for rice grains were evaluated. Surprisingly, rice grains grown on non- or low-polluted soils can surpass the upper limits. According to the UL concept, 12% of the grains exceeded the UL of As, 29% that of Cd, and 27% that of Pb for each gender. According to the MC concept, 5% of the rice grains exceeded the MC of inorganic As for adults and 38% that for young children. 24% of the grains surpassed the MC of Pb, while Cd in all grains was below the MC. The differing results of the UL and MC approaches show an urgent need for revision and harmonization concerning As, Cd, and Pb limits, especially regarding countries with high rice consumption.

Bioaccumulations and potential human health risks assessment of heavy metals in ppk-expressing transgenic rice

In order to reduce the phosphorus (P) resource consume, the polyphosphatekinase (ppk)-expressing transgenic rice (ETR) with high utilization efficiency of P fertilizer had been constructed. However, synthesis polyphosphates (polyP) mediated byppkin the plants have the ability of chelating heavy metals, so the potential hazards of the new elite rice variety have raised concerns. In the study, we planted ETR and wild-type Nipponbare (WT) in paddy fields in southern China. After harvest, the concentrations of eight heavy metals in rice tissues were measured, and health risks assessments were performed. The field experiment showed that the ppkexpressions were detected in the roots and straws of ETR plants but did not increase the concentrations of As, Cd, Cr, Ni and Pb in rice tissues. The Hg concentration in the ETRD root was 1.70-fold higher than that in WT, but the abundant Hg bioaccumulation in ETRD only occurred in the root. The bioaccumulation factors (BAFs) of all the detected heavy metals in the ETRS were no different from WT except for Cu and Zn. The results of human health risks assessment of heavy metals in brown rice showed that the non-carcinogenic risks of Cu or Zn in ETRD were higher than that in WT, while there was no difference in the total noncarcinogenic risk of the eight heavy metals in ETR. The carcinogenic risks of heavy metals in ETR were also comparable to that in WT. The results of this study indicated that the ppk expression in rice did not increase human health risks of heavy metals by consuming brown rice, which would provide a safety guarantee for agricultural and environmental applications of ETR not only with single-copy line but also with double-copy line.

Accumulation of essential and non-essential trace elements in rice grain: Possible health impacts on rice consumers in West Bengal, India

Rice is the major staple food to the population in rural West Bengal, India and Bangladesh. Depletion and excess accumulation of different trace elements, which are essential and non-essential to the human body, in rice can have a detrimental impact on the rice consumer. Therefore, this study has investigated the accumulation of different trace elements in rice consumed in rural households in West Bengal. The mean concentration (mg kg^-1) of essential elements in rice follows the order of Fe (39.4) > Zn (9.79) > Mn (4.40) > Cu (3.26) > Se (0.28) > Co (0.03), while this order for non-essential elements is Pb (1.70) > As (0.34) > Ni (0.22) > Cd (0.04). In general, accumulation in rice is higher for elements that show higher mobility under reducing conditions (e.g. Fe, Mn, As, etc.) compared to elements with lower mobility under such conditions (e.g. Se, Cd, etc.). These orders of accumulation can be attributed to the irrigation practice of continuous flooding of the soil during rice cultivation and the abundance of these elements in the paddy soil itself. By combining these analytical results to the data obtained from questionnaire survey it is estimated that rice consumption can be either enough or a major source to fulfill the daily requirement of Fe, Cu, Se, Mn, and Zn necessary for different physiological functions in the human body for the population in rural Bengal. At the same time, it can be a potential route of As, Cd, Ni, and Pb exposure to develop their non-carcinogenic and carcinogenic health effects among the population. This study highlights that attempts should be made to reduce the accumulation of other non-essential elements together with As in rice grain to ensure the health safety of the people who rarely get a balanced diet and relay on rice consumption to meet the daily calorific intake in rural Bengal.

South Asian Health: Inflammation, Infection, Exposure, and the Human Microbiome

This paper presents the results of the literature review conducted for the working group topic on inflammation, infection, exposure, and the human microbiome. Infection and chronic inflammation can elevate risk for cardiovascular disease and cancer. Environmental exposures common among South Asian (SA) subgroups, such as arsenic exposure among Bangladeshis and particulate matter air pollution among taxi drivers, also pose risks. This review explores the effects of exposure to arsenic and particulate matter, as well as other infections common among SAs, including human papillomavirus (HPV) and hepatitis B/C infection. Emerging research on the human microbiome, and the effect of microbiome changes on obesity and diabetes risk among SAs are also explored.

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 in cooked rice foods: Assessing health risks and mitigation options

Human exposure to arsenic (As) through the consumption of rice (Oryza sativa L.) is a worldwide health concern. In this paper, we evaluated the major causes for high inorganic As levels in cooked rice foods, and the potential of post-harvesting and cooking options for decreasing inorganic As content in cooked rice, focusing particularly on As endemic areas. The key factors for high As concentration in cooked rice in As endemic areas are: (1) rice cultivation on As-contaminated paddy soils; (2) use of raw rice grains which exceed 200 μg kg^-1 of inorganic As to cook rice; and (3) use of As-contaminated water for cooking rice. In vitro and in vivo methods can provide useful information regarding the bioaccessibility of As in the gastrointestinal tract. Urinary levels of As can also be used as a valid measure of As exposure in humans. Polishing of raw rice grains has been found to be a method to decrease total As content in cooked rice. Sequential washing of raw rice grains and use of an excess volume of water for cooking also decrease As content in cooked rice. The major concern with those methods (i.e. polishing of raw rice, sequential washing of raw rice, and use of excess volume of water for cooking rice) is the decreased nutrient content in the cooked rice. Cooking rice in percolating water has recently gained significant attention as a way to decrease As content in cooked rice. Introducing and promoting rainwater harvesting systems in As endemic areas may be a sustainable way of reducing the use of As-contaminated water for cooking purposes. In conclusion, post-harvesting methods and changes in cooking practices could reduce As content in cooked rice to a greater extent. Research gaps and directions for future studies in relation to different post-harvesting and cooking practices, and rainwater harvesting systems are also discussed in this review.

Geographical variation of arsenic distribution in paddy soil, rice and rice-based products: A meta-analytic approach and implications to human health

Arsenic is considered as ubiquitous toxic element belonging to the highest health hazard category. Wide ranges of natural as well as anthropogenic activities are subject to create global arsenic distribution in the broad sense. Rice is the major staple food consumed by world's population on the maximum scale. Growing environment of rice typically attributed by geographical origin may influence on arsenic bioavailability in rice grain. Over exploitation of arsenic contaminated, groundwater resources have recognised as major concern in agricultural perspective for rice production. On the other hand, biogeochemical weathering of arsenic bearing rocks as the geogenic origin, mining activities and application arsenical pesticides are recognised to be well known factors responsible to increase the soil arsenic level. Transfer of arsenic into rice is rightly acquainted from these possible sources of contamination in different regions around the world. Consequently, such substantial geographical variation reflects bioavailability as well as speciation of arsenic in rice. In this manuscript, we discuss the contribution of different arsenic entering pathways in soil-rice systems from regional variability. Furthermore, we attempted to apply the meta-analysis in order to predict the comparative risk assessment on distribution pattern of total and inorganic arsenic in rice commercialised from various rice producing regions of Asia, Europe and US by considering a selected number of data set an extensive range of market basket and field survey. In addition, we finally focus on health risk assessment associated by the consumption of rice and rice-based infant products as the dietary intake from the different of origin. Furthermore, we must detect and categorize the possible source of contamination, which may critically enhance the bioavailability of arsenic in rice in order to minimize the risk. These are the major aspects reviewed here.

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.

Arsenic in groundwater of West Bengal, India: A review of human health risks and assessment of possible intervention options

This paper reviews how active research in West Bengal has unmasked the endemic arsenism that has detrimental effects on the health of millions of people and their offspring. It documents how the pathways of exposure to this toxin/poison have been greatly expanded through intensive application of groundwater in agriculture in the region within the Green Revolution framework. A goal of this paper is to compare and contrast the similarities and differences in arsenic occurrence in West Bengal with those of other parts of the world and assess the unique socio-cultural factors that determine the risks of exposure to arsenic in local groundwater. Successful intervention options are also critically reviewed with emphasis on integrative strategies that ensure safe water to the population, proper nutrition, and effective ways to reduce the transfer of arsenic from soil to crops. While no universal model may be suited for the vast areas of the world affected with by natural contamination of groundwater with arsenic, we have emphasized community-specific sustainable options that can be adapted. Disseminating scientifically correct information among the population coupled with increased community level participation and education are recognized as necessary adjuncts for an engineering intervention to be successful and sustainable.

Arsenic and other elements in drinking water and dietary components from the middle Gangetic plain of Bihar, India: Health risk index

This study investigates the level of contamination and health risk assessment for arsenic (As) and other elements in drinking water, vegetables and other food components in two blocks (Mohiuddinagar and Mohanpur) from the Samastipur district, Bihar, India. Groundwater (80%) samples exceeded the World Health Organization (WHO) guideline value (10μg/L) of As while Mn exceeded the previous WHO limit of 400μg/L in 28% samples. The estimated daily intake of As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn from drinking water and food components were 169, 19, 26, 882, 4645, 14582, 474, 1449 and 12,955μg, respectively (estimated exposure 3.70, 0.41, 0.57, 19.61, 103.22, 324.05, 10.53, 32.21 and 287.90μg per kg bw, respectively). Twelve of 15 cooked rice contained high As concentration compared to uncooked rice. Water contributes (67%) considerable As to daily exposure followed by rice and vegetables. Whereas food is the major contributor of other elements to the dietary exposure. Correlation and principal component analysis (PCA) indicated natural source for As but for other elements, presence of diffused anthropogenic activities were responsible. The chronic daily intake (CDI) and health risk index (HRI) were also estimated from the generated data. The HRI were >1 for As in drinking water, vegetables and rice, for Mn in drinking water, vegetables, rice and wheat, for Pb in rice and wheat indicated the potential health risk to the local population. An assessment of As and other elements of other food components should be conducted to understand the actual health hazards caused by ingestion of food in people residing in the middle Gangetic plain.

Arsenic species in raw and cooked rice: implications for human health in rural Bengal

This study compares the concentrations of total and different species of arsenic (As) in 29 pairs of raw and cooked rice samples collected from households in an area of West Bengal affected by endemic arsenicism. The aim is to investigate the effects of indigenous cooking practice of the rural villagers on As accumulation and speciation in cooked rice. It is found that inorganic As is the predominant species in both raw (93.8%) and cooked rice (88.1%). Cooking of rice with water low in As (<10 μg L(-1)) significantly decreases the total and inorganic As content in cooked rice compared to raw rice. Arsenic concentration is mainly decreased during boiling of rice grains with excess water. Washing of rice grains with low As water has negligible effect on grain As concentration. The study suggests that rice cooking with low As water by the villagers is a beneficial risk reduction strategy. Despite reductions in As content in cooked rice because of cooking with low As water, the consumption of cooked rice represents a significant health threat (in terms of chronic As toxicity) to the study population.

Arsenic contamination in the food chain and its risk assessment of populations residing in the Mekong River basin of Cambodia

In the present study, we investigated the potential arsenic exposure of Cambodian residents from their daily food consumption. Environmental and ecological samples such as paddy soils, paddy rice (unhusked), staple rice (uncooked and cooked), fish and vegetables were collected from Kandal, Kratie and Kampong Cham provinces in the Mekong River basin of Cambodia. After acid-digestion, digestates were chemically analyzed by inductively coupled plasma mass spectrometry. Results revealed that the means of total arsenic concentration ([As]tot) in paddy soils and paddy rice from Kandal were significantly higher than those from Kampong Cham province (t-test, p<0.05). Moreover, a significant positive correlation between the [As]tot in paddy soils and paddy rice was found (r(14) = 0.826, p<0.01). Calculations of arsenic intake from food consumption indicated that the upper end of the range of the daily dose of inorganic arsenic for Kandal residents (0.089-8.386 μg d(-1) kg(-1) body wt.) was greater than the lower limits on the benchmark dose for a 0.5% increased incidence of lung cancer (BMDL0.5 is equal to 3.0 μg d(-1) kg(-1) body wt.). The present study suggests that the residents in Kandal are at risk of arsenic intake from their daily food consumption. However, the residents in Kratie and Kampong Cham provinces are less likely to be exposed to arsenic through their daily dietary intake. To the best of our knowledge, this is the first report estimating the daily intake and daily dose of inorganic arsenic from food consumption in the Mekong River basin of Cambodia.

Assessing mixed trace elements in groundwater and their health risk of residents living in the Mekong River basin of Cambodia

We investigated the potential contamination of trace elements in shallow Cambodian groundwater. Groundwater and hair samples were collected from three provinces in the Mekong River basin of Cambodia and analyzed by ICP-MS. Groundwater from Kandal (n = 46) and Kraite (n = 12) were enriched in As, Mn, Ba and Fe whereas none of tube wells in Kampong Cham (n = 18) had trace elements higher than Cambodian permissible limits. Risk computations indicated that 98.7% and 12.4% of residents in the study areas of Kandal (n = 297) and Kratie (n = 89) were at risk of non-carcinogenic effects from exposure to multiple elements, yet none were at risk in Kampong Cham (n = 184). Arsenic contributed 99.5%, 60.3% and 84.2% of the aggregate risk in Kandal, Kratie and Kampong Cham, respectively. Sustainable and appropriate treatment technologies must therefore be implemented in order for Cambodian groundwater to be used as potable water.

Effect of carbon sources and of sulfate on microbial arsenic mobilization in sediments of West Bengal, India

Arsenic (As) dissolution from sediments into groundwater in the Bengal Delta/West India was investigated. Two experimental sites were choosen with contrasting As concentrations in shallow groundwater. Apparently patches of high-As and low-As sediments occured in close neigbourhood. A fast As mobilization with lactate or ethanol as carbon sources and sulfate as an electron acceptor and a possible influence of indigenous flora because of higher As amounts and an increasing total cell count was observed over a peroid of 110 days. Sucrose was a less suitable carbon source. Inoculation of an arsenate-reducing Pseudomonas putida WB, that was isolated from the sediments did not improve arsenic mobilization. Maximal arsenic concentrations up to 160μg/l were leached out from sediment columns with lactate or ethanol+sulfate in the water at natural groundwater flow, but the majority of the As remained in the sandy sediments. Some correlation of arsenic with Fe, but not with Mn dissolution seems to exist.

Risk of arsenic exposure from drinking water and dietary components: implications for risk management in rural Bengal

This study investigates the risk of arsenic (As) exposure to the communities in rural Bengal, even when they have been supplied with As safe drinking water. The estimates of exposure via dietary and drinking water routes show that, when people are consuming water with an As concentration of less than 10 μg L(-1), the total daily intake of inorganic As (TDI-iAs) exceeds the previous provisional tolerable daily intake (PTDI) value of 2.1 μg day(-1) kg(-1) BW, recommended by the World Health Organization (WHO) in 35% of the cases due to consumption of rice. When the level of As concentration in drinking water is above 10 μg L(-1), the TDI-iAs exceeds the previous PTDI for all the participants. These results imply that, when rice consumption is a significant contributor to the TDI-iAs, supplying water with an As concentration at the current national drinking water standard for India and Bangladesh would place many people above the safety threshold of PTDI. We also found that the consumption of vegetables in rural Bengal does not pose a significant health threat to the population independently. This study suggests that any effort to mitigate the As exposure of the villagers in Bengal must consider the risk of As exposure from rice consumption together with drinking water.

Arsenic exposure to dairy cows in Bangladesh

Food-chain contamination by arsenic (As) is a newly uncovered disaster. Effects of As-contaminated drinking water and paddy straw on the excretion of As through milk, urine, and dung of dairy cows (n = 240) were studied in As-prone areas of Bangladesh. Mean (±SEM) total As (inorganic plus organic) concentration in drinking water, paddy straw [dry weight dw)], cow's urine (specific gravity adjusted to 1.035), dung (dw), and milk (wet weight) were 89.6 ± 6.5 μg/l, 1,114.4 ± 57.3 μg/kg, 123.6 ± 7.6 μg/l, 1,693.0 ± 65.1 μg/kg, and 26.2 ± 2.8 μg/l, respectively. Significantly (p < 0.01) greater As was in Boro straw (1,386.9 ± 71.8 μg/kg) than Aus (702.4 ± 67.1 μg/kg) and Aman (431.7 ± 28.8 μg/kg) straw and in straw irrigated with shallow (1,697.3 ± 81.9 μg/kg) than deep well water (583.6 ± 62.7 μg/kg) and surface water (511.8 ± 30.0 μg/kg). Significant (p < 0.01) positive correlations were found between As contents of cow's urine and drinking water (r = 0.92) as well as cow dung and straw (r = 0.82). Concentrations of As in cow urine, dung, and milk were increased with the relative increment of As in drinking water and/or straw. These results provide evidence that dairy cows excrete ingested As mainly through urine and dung; thus, As biotransformation through milk remains low. This low concentration of As in milk may be of concern when humans are exposed to multiple sources of As simultaneously. Moreover, As in cow dung could be an environmental issue in Bangladesh.

Processing conditions, rice properties, health and environment

Rice is the staple food for nearly two-thirds of the world’s population. Food components and environmental load of rice depends on the rice form that is resulted by different processing conditions. Brown rice (BR), germinated brown rice (GBR) and partially-milled rice (PMR) contains more health beneficial food components compared to the well milled rice (WMR). Although the arsenic concentration in cooked rice depends on the cooking methods, parboiled rice (PBR) seems to be relatively prone to arsenic contamination compared to that of untreated rice, if contaminated water is used for parboiling and cooking. A change in consumption patterns from PBR to untreated rice (non-parboiled), and WMR to PMR or BR may conserve about 43–54 million tons of rice and reduce the risk from arsenic contamination in the arsenic prone area. This study also reveals that a change in rice consumption patterns not only supply more food components but also reduces environmental loads. A switch in production and consumption patterns would improve food security where food grains are scarce, and provide more health beneficial food components, may prevent some diseases and ease the burden on the Earth. However, motivation and awareness of the environment and health, and even a nominal incentive may require for a method switching which may help in building a sustainable society.

Comparison of drinking water, raw rice and cooking of rice as arsenic exposure routes in three contrasting areas of West Bengal, India

Remediation aimed at reducing human exposure to groundwater arsenic in West Bengal, one of the regions most impacted by this environmental hazard, are currently largely focussed on reducing arsenic in drinking water. Rice and cooking of rice, however, have also been identified as important or potentially important exposure routes. Quantifying the relative importance of these exposure routes is critically required to inform the prioritisation and selection of remediation strategies. The aim of our study, therefore, was to determine the relative contributions of drinking water, rice and cooking of rice to human exposure in three contrasting areas of West Bengal with different overall levels of exposure to arsenic, viz. high (Bhawangola-I Block, Murshidibad District), moderate (Chakdha Block, Nadia District) and low (Khejuri-I Block, Midnapur District). Arsenic exposure from water was highly variable, median exposures being 0.02 μg/kg/d (Midnapur), 0.77 μg/kg/d (Nadia) and 2.03 μg/kg/d (Murshidabad). In contrast arsenic exposure from cooked rice was relatively uniform, with median exposures being 0.30 μg/kg/d (Midnapur), 0.50 μg/kg/d (Nadia) and 0.84 μg/kg/d (Murshidabad). Cooking rice typically resulted in arsenic exposures of lower magnitude, indeed in Midnapur, median exposure from cooking was slightly negative. Water was the dominant route of exposure in Murshidabad, both water and rice were major exposure routes in Nadia, whereas rice was the dominant exposure route in Midnapur. Notwithstanding the differences in balance of exposure routes, median excess lifetime cancer risk for all the blocks were found to exceed the USEPA regulatory threshold target cancer risk level of 10(-4)-10(-6). The difference in balance of exposure routes indicate a difference in balance of remediation approaches in the three districts.