Arsenic species in wheat, raw and cooked rice: Exposure and associated health implications

The behavior of arsenic accumulation in onion (Allium cepa) structures by irrigation water: effect of phosphates and arsenic on the total bioactive compounds and antioxidant capacity

The presence of arsenic (As) in irrigation water is a threat to agricultural crops as well as human health. The presence of arsenic and phosphorous in irrigation water influences the behavior of bioaccumulation, biotransfer, and total bioactive compounds in the distinct parts of the onion structure. The present work evaluates the behavior of the bioaccumulation and biotransfer of As in the structures of onion (Allium cepa) through a composite central design and response surface method. The factors employed include the concentration of arsenic (V) and phosphate (V) in the nutritive solution. Additionally, this study analyzes the behavior of the effect that the induced stress has on the total bioactive compounds (phenols and flavonoids) and antioxidant capacity (ABTS and DPPH) in the onion roots. The results showed that the physiological properties, bioaccumulation factors, As transference, and the total bioactive compounds in the onion structure are affected by the competition of As and phosphates (P(V)) in the irrigation water. For concentrations of As and phosphorous of 450 μg L-1 and 0.30 mg L-1 respectively in irrigation water, there are negative effects on the equatorial diameter of the bulb (DE), length, weight of the leaf, and weight of the bulb. Besides, the transference and bioaccumulation factors range from 0.02 to 0.22 and from 2.15 to 7.81, respectively, suggesting that the plant has the ability to accumulate As but exhibits a low translocation ability of As from the root to aerial organs. Besides, it is found for central concentrations of As and phosphorous (450 μg L-1 and 0.30 mg L-1, respectively) in irrigation water, a greater production occurs in total phenolic compounds and antioxidant capacity (ABTS and DPPH) as a response to the stress generated by As.

Iono-metabolomic guided elucidation of arsenic induced physiological and metabolic dynamics in wheat genotypes

Despite the growing concerns about arsenic (As) toxicity, information on wheat adaptability in such an aggravating environment is limited. Thus, the present investigation based on an iono-metabolomic approach is aimed to decipher the response of wheat genotypes towards As toxicity. Wheat genotypes procured from natural conditions were characterized as high As-contaminated (Shri ram-303 and HD-2967) and low As-contaminated (Malviya-234 and DBW-17) based on ICP-MS As accumulation analysis. Reduced chlorophyll fluorescence attributes, grain yield and quality traits, and low grain nutrient status were accompanied by remarkable grain As accumulation in high As-contaminated genotypes, thus imposing a higher potential cancer risk and hazard quotient. Contrarily, in low As-contaminated genotypes, the richness of Zn, N, Fe, Mn, Na, K, Mg, and Ca could probably have supported less grain As accumulation, imparting better agronomic and grain quality traits. Additionally, from metabolomic analysis (LC-MS/MS and UHPLC), abundances of alanine, aspartate, glutamate, quercetin, isoliquiritigenin, trans-ferrulic, cinnamic, caffeic, and syringic bestow Malviya-234 as the best edible wheat genotype. Further, the multivariate statistical analysis (HCA, PCA, and PLS-DA) revealed certain other key metabolites (rutin, nobletin, myricetin, catechin, and naringenin) based genotypic discrimination that imparts strength to genotypes for better adaptation in harsh conditions. Out of the 5 metabolic pathways ascertained through topological analysis, the two main pathways vital for plant's metabolic adjustments in an As-induced environment were: 1. The alanine, aspartate and glutamate metabolism pathway, and 2. The flavonoid biosynthesis pathway. This is also evident from network analysis, which stipulates amino acid metabolism as a prominent As regulatory factor closely associated with flavonoids and phenolics. Therefore, the present findings are useful for wheat breeding programs to develop As adaptive genotypes that are beneficial for crop improvement and human health.

Monitoring arsenic species concentration in rice-based processed products distributed in South Korean markets and related risk assessment

Rice is an important grain as a major source of carbohydrates in Asia but contains more arsenic (As) than other grains. A total of 239 rice-based processed foods (rice, n = 30; rice cake, n = 30; porridge, n = 39; noodles, n = 33; bread, n = 20; snack, n = 59; powder, n = 28) were purchased in 2019 from domestic markets to measure total As (tAs) and As species. The average tAs and inorganic As (iAs) in each sample group ranged from 20 to 180 μg/kg (porridge for baby to noodle) and 4.4-85 μg/kg (porridge for baby to powder), respectively. The correlation between the iAs and tAs was affected by the variety of ingredients, such as the presence of seaweed (tAs) and the milling type of rice (iAs). Although rice cakes and baby rice-based powders are a source of concern for both adults and children, respectively, risk assessments indicate that most rice-based foods are generally safe to consume in South Korea.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01270-9.

Key factors influencing arsenic phytotoxicity thresholds in south China acidic soils

Arsenic (As) toxicity threshold values (TTVs) for plants are fundamental to both establishing regional As reference values in soil and performing risk assessment. However, TTVs vary with plant species and soil types. In this study, a hydroponic experiment with 16 plant species was conducted to screen the most As-sensitive plant species. The results showed that the EC20 (available As concentration at which shoot biomass or height is inhibited by 20%) values were 1.38-104.4 mg L-1 for shoot height and 0.24-42.87 mg L-1 for shoot fresh biomass. Rice was more sensitive to As toxicity than the other species. Therefore, it was chosen as the ecological receptor in the pot experiment on As phytotoxicity in nine types of soils collected from Fujian Province in South China. The EC10 and EC20 with respect to rice shoot height were 3.72-29.11 mg kg-1 and 7.12-45.60 mg kg-1, respectively. Stepwise regression analysis indicated that free iron oxide concentration is the major factor that affects As bioavailability in soil, and ECx (x = 10, 20, and 50) of soil available As for shoot height was positively related to free iron oxide concentration in soil. In addition, soil cation exchange capacity, clay (<0.002 mm) content, and exchangeable magnesium content are also important factors influencing As phytotoxicity in acidic soils. The regression models can be used to predict As phytotoxicity in acidic soils.

Spatiotemporal distribution and probabilistic health risk assessment of arsenic in drinking water and wheat in Northwest China

Drinking water arsenic poisoning has been a health concern, however the importance of dietary arsenic exposure to health also needs to be taken into account. The aim of this study was to conduct a comprehensive health risk assessment of arsenic-contaminated substances in drinking water and wheat-based food intake in the Guanzhong Plain, China. 87 samples of wheat and 150 samples of water were randomly selected from the research region and examined. The level of arsenic in 89.33% of the water samples in the region exceeded the limit for drinking water (10 μg/L), with an average concentration of 29.98 μg/L. The arsenic in 2.13% of the wheat samples exceeded the food limit (0.5 mg/kg) with an average concentration of 0.24 mg/kg. Under the situation of different exposure pathways, two scenarios of deterministic and probabilistic health risk assessments were compared and analyzed. By contrast, the probabilistic health risk assessment can ensure a certain degree of confidence in the assessment results. The findings of this study indicated that the total cancer risk value faced by the population aged 3-79 years, except for those aged 4-6 years, was 1.03E-4-1.21E-3, which exceeded the 10E-6-10E-4 range of thresholds usually used by USEPA as guidance recommendations for determination. And the non-cancer risk experienced by the population aged 6 months to 79 years was higher than the acceptable threshold (1), with children aged 9 months to 1 year having the highest total non-cancer risk of 7.25. The potential health risks of the exposed population were mainly due to the drinking water route, and consumption of arsenic-containing wheat increased both carcinogenic and non-carcinogenic risks. Finally, the sensitivity analysis revealed that the assessment findings were most significantly influenced by exposure time. The amount of intake was the second influencing factor in the health risk assessment from drinking water and dietary intakes of arsenic, and arsenic concentration was the second influencing factor in the health risk assessment due to dermal exposure to arsenic. The findings of this study can aid in understanding the negative health consequences of arsenic pollution to local residents and in adopting focused remediation strategies to alleviate environmental concerns.

Assessing the risk of human exposure to bioaccessible arsenic from total diet through market food consumption in Chengdu, China

To assess the daily intake of total arsenic (tAs) and arsenic speciation and their potential health risks, different food groups, including vegetables, rice, meat, viscera, freshwater fish, and seafood from Chengdu, China were analyzed. The concentrations of tAs ranged from 41.3 to 1185 μg kg^-1 with a median of 238 μg kg^-1, and 26.0% of tAs in the food groups was of inorganic toxic form. The median concentration of As(V) in rice (184 ± 21.6 μg kg^-1) was approximately 2 to 6 times higher than those in other food groups. The bioaccessible inorganic arsenic (iAs) concentrations of the food items obtained from the local markets of Chengdu ranged from 1.07 to 24.6 μg kg^-1 (mean of 6.04 μg kg^-1). Rice contributed toward the largest amount of daily iAs intake (66.2%). The mean daily iAs intake from vegetable, meat and viscera contributed 10.7%, 12.5% and 6.04% of total iAs intake, respectively. The actual concentration of arsenic in the food exposed to the human body depends on oral bioaccessible fraction. The oral bioaccessibility estimated daily intake (μg kg^-1 bw d^-1) of tAs and iAs for the residents of Chengdu was 0.32 and 0.16. Health risk assessments carried out based on bioaccessible iAs concentrations showed that the food items were safe for consumption from the iAs perspective.

Chronic dietary exposure to total arsenic, inorganic arsenic and water-soluble organic arsenic species based on results of the first German total diet study

For risk assessment purposes, the dietary exposure to total arsenic and inorganic arsenic was estimated within the first German total diet study (BfR MEAL Study) for the whole population in Germany. Therefore, occurrence data of 356 different foods from the BfR MEAL Study were combined with consumption data from German nutrition surveys. Due to the different toxicological potentials of other water-soluble organic arsenic species present in rice-based foods, fish and seafood, dietary exposure to dimethylarsinic acid, monomethylarsonic acid and arsenobetaine was assessed in consumers in Germany through such foods for the first time. Related to the bodyweight, dietary exposure to total arsenic and inorganic arsenic in infants and young children (0.5-<5 years) were higher than in adolescents/adults (≥14 years). The highest median exposure estimates to inorganic arsenic resulted for the age group of infants from 0.5 to <1 year under modified lower bound conditions and for young children from 1 to <2 years under upper bound conditions (0.17 μg kg^-1 bodyweight day^-1-0.24 μg kg^-1 bodyweight day^-1 and 0.26 μg kg^-1 bodyweight day^-1-0.34 μg kg^-1 bodyweight day^-1, respectively). 'Grains and grain-based products' (especially rice) were identified as the main contributors for dietary exposure to total arsenic and inorganic arsenic for all age classes. Especially, for infants and young children, high consumption of rice-based foods and fish fingers is driving the dietary exposure to dimethylarsinic acid. The dietary exposure calculations indicate that a further reduction of dietary exposure to inorganic arsenic and further investigations to water-soluble organic arsenic species are necessary.

Assessment of cause-specific mortality and disability-adjusted life years (DALYs) induced by exposure to inorganic arsenic through drinking water and foodstuffs in Iran

The health risk and burden of disease induced by exposure to inorganic arsenic (iAs) through drinking water and foodstuffs in Iran were assessed. The iAs levels in drinking water and foodstuffs (15 food groups) in the country were determined through systematic review of three international databases (PubMed, Scopus, and Web of Science) and meta-analysis. Based on the results of the systematic review and meta-analysis, the average iAs levels in drinking water and all the food groups at the national level were lower than the maximum permissible levels. The total average non-carcinogenic risk of dietary exposure to iAs in terms of hazard index (HI) was 3.4. The average incremental lifetime cancer risk (ILCR) values of dietary exposure to iAs were determined to be 1.5 × 10^-3 for skin cancer, 1.0 × 10^-3 for lung cancer, and 4.0 × 10^-4 for bladder cancer. Over two-thirds of the non-carcinogenic and carcinogenic risk of dietary exposure to iAs was attributed to bread and cereals, drinking water, and rice. The total annual cancer incidence, deaths, disability-adjusted life years (DALYs), death rate, and DALY rate (per 100,000 people) were assessed to be 3347 (95 % uncertainty interval: 1791 to 5999), 1302 (697 to 2336), 72,606 (38,833 to 130,228), 1.6 (0.87 to 2.9), and 91 (49 to 160). The contribution of mortality in the attributable burden of disease was 95.1 %. The contributions of the causes in the attributable burden of disease were 72 % for lung cancer, 16 % for bladder cancer, and 12 % for skin cancer. Due to the significant attributable burden of disease, national and subnational action plans consisting of multi-disciplinary approaches for risk management of dietary exposure to iAs, especially for the higher arsenic-affected areas and high-risk population groups in the country are recommended.

Contemporary Comprehensive Review on Arsenic-Induced Male Reproductive Toxicity and Mechanisms of Phytonutrient Intervention

Arsenic (As) is a poisonous metalloid that is toxic to both humans and animals. Drinking water contamination has been linked to the development of cancer (skin, lung, urinary bladder, and liver), as well as other disorders such as diabetes and cardiovascular, gastrointestinal, neurological, and developmental damage. According to epidemiological studies, As contributes to male infertility, sexual dysfunction, poor sperm quality, and developmental consequences such as low birth weight, spontaneous abortion, and small for gestational age (SGA). Arsenic exposure negatively affected male reproductive systems by lowering testicular and accessory organ weights, and sperm counts, increasing sperm abnormalities and causing apoptotic cell death in Leydig and Sertoli cells, which resulted in decreased testosterone synthesis. Furthermore, during male reproductive toxicity, several molecular signalling pathways, such as apoptosis, inflammation, and autophagy are involved. Phytonutrient intervention in arsenic-induced male reproductive toxicity in various species has received a lot of attention over the years. The current review provides an in-depth summary of the available literature on arsenic-induced male toxicity, as well as therapeutic approaches and future directions.

Recent advancements in toxicology, modern technology for detection, and remedial measures for arsenic exposure: review

Arsenic toxicity has become a major global health concern for humans and animals due to extensive environmental and occupational exposure to arsenic-contaminated water, air, soil, and plant and animal origin food. It has a wide range of detrimental effects on animals, humans, and the environment. As a result, various experimental and clinical studies were undertaken and are undergoing to understand its source of exposures, pathogenesis, identify key biomarkers, the medical and economic impact on affected populations and ecosystems, and their timely detection and control measures. Despite these extensive studies, no conclusive information for the prevention and control of arsenic toxicity is available, owing to complex epidemiology and pathogenesis, including an imprecise approach and repetitive work. As a result, there is a need for literature that focuses on recent studies on the epidemiology, pathogenesis, detection, and ameliorative measures of arsenic toxicity to assist researchers and policymakers in the practical future planning of research and community control programs. According to the preceding viewpoint, this review article provides an extensive analysis of the recent progress on arsenic exposure to humans through the environment, livestock, and fish, arsenic toxicopathology, nano-biotechnology-based detection, and current remedial measures for the benefit of researchers, academicians, and policymakers in controlling arsenic eco-toxicology and directing future research. Arsenic epidemiology should therefore place the greatest emphasis on the prevalence of different direct and indirect sources in the afflicted areas, followed by control strategies.

Sulfur reduces the root-to-shoot translocation of arsenic and cadmium by regulating their vacuolar sequestration in wheat (Triticum aestivum L.)

Accumulation of arsenic (As) and cadmium (Cd) in wheat grain is a serious threat to human health. Sulfur (S) can simultaneously decrease wheat grain As and Cd concentrations by decreasing their translocation in wheat; however, the mechanisms are unclear. We conducted hydroponic experiments to explore the mechanisms by which S modulates As and Cd translocation and their toxicity in wheat. Wheat seedlings were grown in deficient sulfate (2.5 µM) or sufficient sulfate (1.0 mM) nutrient solutions for 6 days and then exposed to zero (control), low As+Cd (1 µM As plus 0.5 µM Cd), or high As+Cd (50 µM As plus 30 µM Cd) for another 6 days. Compared with the control, plant growth was not affected by low As+Cd, but was significantly inhibited by high As+Cd. In the low As+Cd treatment, S supply had no significant effect on plant growth or root-to-shoot As and Cd translocation. In the high As+Cd treatment, sufficient S supply significantly alleviated As and Cd toxicity and their translocation by increasing phytochelatin (PC) synthesis and the subsequent vacuolar sequestration of As and Cd in roots, compared with deficient S supply. The use of _L-buthionine sulfoximine (a specific inhibitor of γ-glutamylcysteine synthetase) confirmed that the alleviation of As and Cd translocation and toxicity in wheat by S is mediated by increased PC production. Also, TaHMA3 gene expression in wheat root was not affected by the As+Cd and S treatments, but the expression of TaABCC1 was upregulated by the high As+Cd treatment and further increased by sufficient S supply and high As+Cd treatment. These results indicate that S-induced As and Cd subcellular changes affect As and Cd translocation mainly by regulating thiol metabolism and ABCC1 expression in wheat under As and Cd stress.

Arsenic contribution of poultry manure towards soils and food plants contamination and associated cancer risk in Khyber Pakhtunkhwa, Pakistan

Exposure to high level of arsenic (As) through the ingestion of contaminated soil, dust and food plants can pose health risk to humans. This study investigates the total arsenic (As), arsenobetaine (AsB), monomethylarsenate (MMA), dimethylarsenate (DMA), arsenite (As³⁺) and arsenate (As⁵⁺) concentrations in poultry feed, manure, agricultural soils and food plants collected from Khyber Pakhtunkhwa Province, Pakistan. The total mean As concentrations in the edible parts of food plants ranged from 0.096 mg kg^-1 to 1.25 mg kg^-1 with percentile (P) values (P25-0.039, P50-0.0765, P75-0.165 1 mg kg^-1 to P25-0.95, P50-1.23, P75-1.6 1 mg kg^-1) and exceeded the food safety limit (0.1 mg kg^-1) of Food & Agriculture Organization (FAO) and World Health Organization (WHO) in all plant species except Pisum sativum (pea) and Mentha arvensis (mint). The risk to human health was assessed through the average daily intake (ADI), hazards quotient (HQ), health risk index (HRI) and lifetime cancer risk (LTCR). The highest average daily intake of As via the ingestion of Malva neglecta (mallow, a leafy plant) was observed for adults and children. The ADI for adults and children (2.36 × 10^-4 mg kg^-1 day^-1 and 6.33 × 10^-4 mg kg^-1 day^-1) was about 13% and 5%, respectively, of the Bench Mark Dose Limit (BMDL_0.5) of 3.00 × 10^-3 mg kg^-1 day^-1 set by WHO. The HRI was 3 times more in the children (2.1) than the adults (0.79), posing non-cancer health risks (health risk index > 1) for children. The LTCR values were slightly higher (1.53 × 10^-4) relative to USEPA and WHO limits (1 × 10^-6 to 1 × 10^-4) for children whereas a minimal cancer risk was observed for adults via consumption of selected food plants. The results showed that poultry manure can contaminate food plants that may lead to cancer and non-cancer risks in agricultural areas, Pakistan. Thus, it is important to minimize As concentration in poultry feed to safeguard human health and environment from adverse effects.

Hydrogeochemical analysis of groundwater quality for drinking and irrigation with elevated arsenic and potential impact on agro-ecosystem in the upper Brahmaputra plain, India

The upper Brahmaputra floodplain is considerably enriched with geogenic contaminants, mainly Arsenic (As) exhibiting high spatial heterogeneity. With this concern, the present study was conducted in Lakhimpur district located in the upper Brahmaputra floodplain aiming to assess the groundwater (GW) suitability for drinking and irrigation. Chemical analysis of 78 GW samples revealed significantly high As (max 0.12 mgL^-1, mean 0.02 mgL^-1) followed by iron (max 62.2 mgL^-1, mean 19.94 mgL^-1) showing uneven distribution. Hydrogeochemical analysis of the GW samples revealed that majority of the water samples belong to mixed Ca²⁺- Na⁺- HCO₃^- type with weathering and forward ion exchange as the dominant processes in the aquifer system. Positive correlation among iron (Fe) and As, together with close grouping in hierarchical cluster analysis and principal components analysis, indicated the involvement of reductive hydrolysis process. Calculation of saturation indices indicated that, precipitation of Fe minerals may lead to de-coupling of Fe and As contributing to the enrichment of both the elements in the GW. Further, assessment of key parameters for irrigation water quality including water quality index indicated the GW to be suitable for irrigation purpose. Finally, toxicity implications of crops produced from As contaminated water indicated higher accumulation potential of As in the food grains implying significant impacts on the agro-ecosystem and associated health hazards.

Effects of low molecular weight organic acids with different functional groups on arsenate adsorption on birnessite

In an aquatic ecosystem, especially constructed wetlands receiving arsenic (As)-containing wastewater, the fate and mobility of As is influenced by manganese (Mn) oxides and organic matter. Although Mn oxides have been extensively investigated for As(V) adsorption, effects of low molecular weight organic acids (LMWOAs) with different functional groups on As(V) adsorption onto birnessite and underlying mechanisms remain elusive. In this study, LMWOAs with two carboxyl groups (including tartaric (TA), malate (MA), and succinic acids (SA) with two, one and zero hydroxyl groups, respectively) were used. Results showed that more As(V) was adsorbed on birnessite with the presence of LMWOA, indicating that the LMWOA promoted As(V) adsorption via birnessite-carboxyl-As(V) ternary complex. Before birnessite dissolution, TA and MA facilitated As(V) adsorption more efficiently than SA, indicating that hydroxyl group enhanced the coordination among carboxyl groups, As(V) and birnessite. However, within high TA/MA batches, As(V) concentrations decreased sharply and then gradually increased, but Mn(II) concentrations continuously increased, showing the initial reductive dissolution of birnessite promoted As adsorption, while further dissolution was conducive to As mobilization. This study identifies the mechanisms of As adsorption in the presence of LMWOAs and highlights the importance of functional groups in As fate and mobility in aqueous environments.

Widespread Occurrence of the Highly Toxic Dimethylated Monothioarsenate (DMMTA) in Rice Globally

Arsenic (As) accumulation in rice is of global concern for human health and international trade. Rice is typically reported to contain inorganic As (iAs) and dimethylated arsenate (DMA), with current food guidelines limiting toxic iAs but not less-toxic DMA. Here, we show that the highly toxic dimethylated monothioarsenate (DMMTA) is also found in rice worldwide and has been unknowingly determined as less-toxic DMA by previous routine analytical methods. Using enzymatic extraction followed by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) analysis with a C18 column, DMMTA was detected in rice grains (n = 103) from a field survey from China and in polished rice grains (n = 140) from a global market-basket survey. Concentration ranged from <0.20 to 34.8 μg/kg (median 10.3 μg/kg), accounting for 0 to 21% of total As. A strong linear correlation was observed in all rice samples between DMA and DMMTA (being 30 ± 8% of DMA) concentrations. This robust relationship allows an estimation of DMMTA in rice grains from the DMA data reported in previous market-basket surveys, showing a general global geographical pattern with DMMTA concentration increasing from the equator toward high-latitude regions. Based on the global occurrence and potential high toxicity, DMMTA in rice should be considered in health risk assessments and for setting food regulations.

Biological Properties of Vitamins of the B-Complex, Part 1: Vitamins B1, B2, B3, and B5

This review summarizes the current knowledge on essential vitamins B₁, B₂, B₃, and B₅. These B-complex vitamins must be taken from diet, with the exception of vitamin B₃, that can also be synthetized from amino acid tryptophan. All of these vitamins are water soluble, which determines their main properties, namely: they are partly lost when food is washed or boiled since they migrate to the water; the requirement of membrane transporters for their permeation into the cells; and their safety since any excess is rapidly eliminated via the kidney. The therapeutic use of B-complex vitamins is mostly limited to hypovitaminoses or similar conditions, but, as they are generally very safe, they have also been examined in other pathological conditions. Nicotinic acid, a form of vitamin B₃, is the only exception because it is a known hypolipidemic agent in gram doses. The article also sums up: (i) the current methods for detection of the vitamins of the B-complex in biological fluids; (ii) the food and other sources of these vitamins including the effect of common processing and storage methods on their content; and (iii) their physiological function.

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.

Impact of organic and inorganic amendments on arsenic accumulation by rice genotypes under paddy soil conditions: A pilot-scale investigation to assess health risk

In this study, we investigated the distinct effects of organic (farmyard manure (FYM), cow dung (CD), biogas slurry (BGS), sugarcane bagasse (SCB)) and inorganic (gypsum and lignite) amendments on arsenic (As) accumulation by two rice genotypes, Kainat (fine) and Basmati-385 (coarse), under As stress. Results showed that shoot As concentration was ~2-time greater in Kainat compared to Basmati-385 (3.1-28 vs. 1.7-16 mg kg^-1 DW, respectively), with the minimum shoot As content observed with CD and SCB. In contrast to gypsum and lignite, grain As concentration was significantly reduced with CD and SCB for Kainat (0.29 and 0.24 mg kg^-1 DW) and Basmati-385 (0.04 and 0.09 mg kg^-1 DW). Data indicated that the CD and SCB also improved chlorophyll a and b contents, reduced lipid peroxidation and hydrogen peroxide production in both rice genotypes. Significantly, the CD and SCB decreased grain As concentration below the FAO safe As limit in rice grain (0.2 mg kg^-1 DW), especially in coarse rice genotype (Basmati-385), resulting in negligible As-induced human health risk. This study highlights the significance of amendments and rice genotypes controlling As accumulation in rice grain, which should be considered prior to As remediation program of paddy soils for limiting exposure of humans to As via rice grain.

Arsenate and Arsenite Sorption Using Biogenic Iron Compounds: Treatment of Real Polluted Waters in Batch and Continuous Systems

Arsenic pollution in waters is due to natural and anthropogenic sources. Human exposure to arsenic is associated with acute health problems in areas with high concentrations of this element. Nanometric iron compounds with large specific surface areas and higher binding energy produced by some anaerobic microorganisms are thus expected to be more efficient adsorbents for the removal of harmful metals and metalloids than chemically produced iron oxides. In this study, a natural consortium from an abandoned mine site containing mainly Clostridium species was used to biosynthesize solid Fe(II) compounds, siderite (FeCO3) and iron oxides. Biogenic precipitates were used as adsorbents in contact with solutions containing arsenate and arsenite. The adsorption of As(V) fitted to the Langmuir model (qmax = 0.64 mmol/g, KL = 0.019 mmol/L) at the optimal pH value (pH 2), while the As(III) adsorption mechanism was better represented by the Freundlich model (KF = 0.476 L/g, n = 2.13) at pH 10. Water samples from the Caracarani River (Chile) with high contents of arsenic and zinc were treated with a biogenic precipitate encapsulated in alginate beads in continuous systems. The optimal operation conditions were low feed flow rate and the up-flow system, which significantly improved the contaminant uptake. This study demonstrates the feasibility of the application of biogenic iron compounds in the treatment of polluted waters.

Screening of Pioneer Metallophyte Plant Species with Phytoremediation Potential at a Severely Contaminated Hg and As Mining Site

Phytoremediation of mine soils contaminated by potentially toxic elements (PTEs) requires the use of tolerant plants given the specific conditions of toxicity in the altered soil ecosystems. In this sense, a survey was conducted in an ancient Hg-mining area named “El Terronal” (Asturias, Spain) which is severely affected by PTE contamination (As, Hg, Pb) to obtain an inventory of the spontaneous natural vegetation. A detailed habitat classification was performed and a specific index of coverage was applied after a one-year quadrat study in various sampling stations; seven species were finally selected (Agrostis tenuis, Betula celtiberica, Calluna vulgaris, Dactylis glomerata, Plantago lanceolata, Salix atrocinerea and Trifolium repens). A total of 21 samples (3 per plant) of the soil–plant system were collected and analyzed for the available and total concentrations of contaminants in soil and plants (roots and aerial parts). Most of the studied plant species were classified as non-accumulating plants, with particular exceptions as Calluna vulgaris for Pb and Dactylis glomerata for As. Overall, the results revealed interest for phytoremediation treatments, especially phytostabilization, as most of the plants studied were classified as excluder metallophytes.

Depletion of S-adenosylmethionine pool and promoter hypermethylation of Arsenite methyltransferase in arsenic-induced skin lesion individuals: A case-control study from West Bengal, India

Methylation of arsenic compounds in the human body occurs following a series of biochemical reactions in the presence of methyl donor S-adenosylmethionine (SAM) and catalyzed by arsenite methyltransferase (AS3MT). However, the extent and pattern of methylation differs among the arsenic exposed individuals leading to differential susceptibility. The mechanism for such inter-individual difference is enigmatic. In the present case-control study we recruited exposed individuals with and without arsenic induced skin lesion (WSL and WOSL), and an unexposed cohort, each having 120 individuals. Using ELISA, we observed a reduction in SAM levels (p < 0.05) in WSL compared to WOSL. Linear regression analysis revealed a negative correlation between urinary arsenic concentration and SAM concentration between the study groups. qRT-PCR revealed a significant down-regulation (p < 0.01) of key regulatory genes like MTHFR, MTR, MAT2A and MAT2B of SAM biogenesis pathway in WSL cohort. Methylation-specific PCR revealed significant promoter hypermethylation of AS3MT (WSL vs. WOSL: p < 0.01) which resulted in its subsequent transcriptional repression (WSL vs. WOSL: p < 0.001). Linear regression analysis also showed a negative correlation between SAM concentration and percentage of promoter methylation. Taken together, these results indicate that reduction in SAM biogenesis along with a higher utilization of SAM results in a decreased availability of methyl donor. These along with epigenetic down-regulation of AS3MT may be responsible for higher susceptibility in arsenic exposed individuals.

Total arsenic and water-soluble arsenic species in foods of the first German total diet study (BfR MEAL Study)

Arsenic can occur in foods as inorganic and organic forms. Inorganic arsenic is more toxic than most water-soluble organic arsenic compounds such as arsenobetaine, which is presumed to be harmless for humans. Within the first German total diet study, total arsenic, inorganic arsenic, arsenobetaine, dimethylarsinic acid and monomethylarsonic acid were analyzed in various foods. Highest levels of total arsenic were found in fish, fish products and seafood (mean: 1.43 mg kg-1; n = 39; min-max: 0.01-6.15 mg kg-1), with arsenobetaine confirmed as the predominant arsenic species (1.233 mg kg-1; n = 39; min-max: 0.01-6.23 mg kg-1). In contrast, inorganic arsenic was determined as prevalent arsenic species in terrestrial foods (0.02 mg kg-1; n = 38; min-max: 0-0.11 mg kg-1). However, the toxicity of arsenic species varies and measurements are necessary to gain information about the composition and changes of arsenic species in foods due to household processing of foods.

Brazilian Genetic Diversity for Desirable and Undesirable Elements in the Wheat Grain

Micronutrient deficiency affects billions of people, especially in countries where the diet is low in diversity with inadequate consumption of fruits, vegetables, and animal-source foods, and higher consumption of staple food, i.e., cereals, that have low concentrations of micronutrients. Genetic biofortification is a strategy to mitigate this problem and ensure nutritional security. Wheat is a target of genetic biofortification since it contributes significantly to the caloric requirement. The biofortification process involves a screening related to the presence of genetic variability for grain mineral content. Also, the accumulation of toxic elements must be considered to ensure food safety, because if ingested above the allowed concentrations, it represents health risks. In this sense, this study aimed to quantify the micronutrients iron, zinc, copper, selenium, and manganese and toxic elements arsenic and cadmium in a Brazilian wheat panel grown in Southern Brazil. The presence of genetic variability for the accumulation of micronutrients in the grain was detected; however, we observed that only the copper and manganese accumulation meet the human daily requirements. Iron, zinc, and selenium were detected in insufficient concentration to meet the daily demand. Arsenic and cadmium accumulation were not detected in wheat grain. The wheat genotypes grown in Brazil displayed a similar profile to that found in other countries which may be due to common high-yield breeding goals and the narrowing of the genetic variability, observed worldwide. Thus, the wheat genetic biofortification success in Brazil depends on the introduction of foreign genotypes, landraces, and wild relatives.

Decreases in arsenic accumulation by the plasma membrane intrinsic protein PIP2;2 in Arabidopsis and yeast

Arsenic (As) is a toxic pollutant that mainly enters the human body via plants. Therefore, understanding the strategy for reducing arsenic accumulation in plants is important to human health and the environment. Aquaporins are ubiquitous water channel proteins that bidirectionally transport water across cell membranes and play a role in the transportation of other molecules, such as glycerol, ammonia, boric acid, and arsenic acid. Previously, we observed that Arabidopsis PIP2;2, encoding a plasma membrane intrinsic protein, is highly expressed in NtCyc07-expressing Arabidopsis, which shows a higher tolerance to arsenite (As(III)). In this study, we report that the overexpression of AtPIP2;2 enhanced As(III) tolerance and reduced As(III) levels in yeast. Likewise, AtPIP2;2-overexpressing Arabidopsis exhibited improved As(III) tolerance and lower accumulation of As(III). In contrast, atpip2;2 knockout Arabidopsis showed reduced As(III) tolerance but no significant change in As(III) levels. Interestingly, the AtPIP2;2 transcript and protein levels were increased in roots and shoots of Arabidopsis in response to As(III). Furthermore, As(III) efflux was enhanced and As(III) influx/accumulation was reduced in AtPIP2;2-expressing plants. The expression of AtPIP2;2 rescued the As(III)-sensitive phenotype of acr3 mutant yeast by reducing As levels and slightly reduced the As(III)-tolerant phenotype of fps1 mutant yeast by enhancing As content, suggesting that AtPIP2; 2 functions as a bidirectional channel of As(III), while the As(III) exporter activity is higher than the As(III) importer activity. All these results indicate that AtPIP2;2 expression promotes As(III) tolerance by decreasing As(III) accumulation through enhancing As(III) efflux in Arabidopsis. This finding can be applied to the generation of low arsenic crops for human health.

Variety-specific arsenic accumulation in 44 different rice cultivars (O. sativa L.) and human health risks due to co-exposure of arsenic-contaminated rice and drinking water

Arsenic (carcinogenic) is a global health concern due to its presence in groundwater and subsequent accumulation in cultivated-rice via irrigation. The present work focused on the evaluation of arsenic concentration in groundwater, different cultivated-rice varieties (studied together for the first-time) and related health-risks. Arsenic in groundwater (0.26-0.73 mg/L) exceeded the World Health Organization limit for drinking water (0.01 mg/L). Arsenic concentration in rice-grains was found in the range: < 0.0003-2.6 mg/kg dry-weights, where 42 rice varieties (out of total 44) exceeded the Codex Alimentarius Commission limit of polished-rice (0.2 mg/kg). The variety-specific differential-response of arsenic-accumulation was observed (first-time report), where high yielding rice varieties (HYV) were more prone to accumulate arsenic in comparison to local varieties (LV), however, 'Radhunipagol' (an aromatic LV) exhibited as a moderate arsenic-accumulator (BCF = 2.8). The cumulative estimated-daily-intakes (EDI_Cumulative) of arsenic in central-tendency-exposure were observed to be 0.029, 0.031 and 0.04 mg/kg-day among children, teenagers and adults, respectively. The EDI_Cumulative for possible reasonable-maximum-exposure among the above mentioned subpopulation was 0.038, 0.04 and 0.05 mg/kg-day, respectively. The evaluated Cumulative Hazard Index and Individual Excess Lifetime Cancer Risk values suggested that the studied population is under extremely severe cancerous and noncancerous risks to arsenic co-exposures via drinking water and rice.

Arbuscular Mycorrhiza Improves Photosynthesis and Restores Alteration in Sugar Metabolism in Triticum aestivum L. Grown in Arsenic Contaminated Soil

Contamination of agricultural soil by arsenic (As) is a serious menace to environmental safety and global food security. Symbiotic plant-microbe interaction, such as arbuscular mycorrhiza (AM), is a promising approach to minimize hazards of As contamination in agricultural soil. Even though the potential of AM fungi (AMF) in redeeming As tolerance and improving growth is well recognized, the detailed metabolic and physiological mechanisms behind such beneficial effects are far from being completely unraveled. The present study investigated the ability of an AM fungus, Rhizophagus intraradices, in mitigating As-mediated negative effects on photosynthesis and sugar metabolism in wheat (Triticum aestivum) subjected to three levels of As, viz., 0, 25, and 50 mg As kg-1 of soil, supplied as sodium arsenate. As exposure caused significant decrease in photosynthetic pigments, Hill reaction activity, and gas exchange parameters such as net photosynthetic rate, stomatal conductance, transpiration rate, and intercellular CO2 concentration. In addition, As exposure also altered the activities of starch-hydrolyzing, sucrose-synthesizing, and sucrose-degrading enzymes in leaves. Colonization by R. intraradices not only promoted plant growth but also restored As-mediated impairments in plant physiology. The symbiosis augmented the concentration of photosynthetic pigments, enhanced Hill reaction activity, and improved leaf gas exchange parameters and water use efficiency of T. aestivum even at high dose of 50 mg As kg-1 of soil. Furthermore, inoculation with R. intraradices also restored As-mediated alteration in sugar metabolism by modulating the activities of starch phosphorylase, α-amylase, β-amylase, acid invertase, sucrose synthase, and sucrose-phosphate synthase in leaves. This ensured improved sugar and starch levels in mycorrhizal plants. Overall, the study advocates the potential of R. intraradices in bio-amelioration of As-induced physiological disturbances in wheat plant.

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.

Comparison of Plasma Concentrations of Mercury, Cadmium, and Arsenic among Women in 2005 and 2012 in a Historically Contaminated Area in China

Mercury (Hg), cadmium (Cd), and arsenic (As) concentrations in women were measured and compared to evaluate the effects of environmental heavy-metal pollution control on internal exposure levels. In 2005 and 2012, 200 and 182 women, respectively, were enrolled in the study. Demographic and diet information were collected using a questionnaire. Fasting venous blood samples were collected, and plasma concentrations of Hg, Cd, and As were measured using inductive coupled plasma mass spectrometry. The median concentrations (P₂₅-P₇₅) of Hg, Cd, and As decreased from 0.56 (0.46-0.75) ng/mL, 0.14 (0.09-0.21) ng/mL, and 0.83 (0.66-1.09) ng/mL in 2005 to 0.39 (0.19-0.66) ng/mL, 0.09 (0.05-0.13) ng/mL, and 0.48 (0.29-0.72) ng/mL in 2012, respectively. The difference in plasma metal concentrations between measurements in 2005 and 2012 remained statistically significant after we adjusted for confounders. The adjusted ORs were 0.31 (0.16-0.60), 0.24 (0.12-0.48), and 0.25 (0.13-0.50) for Hg, Cd, and As concentrations, respectively, in 2012, relative to those in 2005. The levels of Hg, Cd, and As were 30% to 40% lower in 2012 than in 2005, indicative of lower human internal exposure to these contaminants due to the implementation of environmental pollution control. Engagement with agriculture and high-frequency water product consumption were associated with high Hg levels, and a high frequency of consumption of fresh fruit and eggs was negatively associated with lower levels of Cd in plasma.

Geographical variations in arsenic contents in rice plants from Latin America and the Iberian Peninsula in relation to soil conditions

Arsenic is a ubiquitous, toxic element that is efficiently accumulated by rice plants. This study assessed the spatial variability in the total As (tAs) contents and organic and inorganic forms in different types of rice, plant parts (husk, stem, leaves and phytoliths) and residues. Samples were collected in different countries in Latin America (Ecuador, Brazil and Peru) and the Iberian Peninsula (Spain and Portugal). The tAs content in commercial polished rice from the Latin American countries was similar (0.130-0.166 mg kg^-1) and significantly lower than in the rice from the Iberian countries (0.191 ± 0.066 mg kg^-1), and together, the tAs concentration in brown rice (236 ± 0.093 mg kg^-1) was significantly higher than in polished and parboiled rice. The inorganic As (iAs) content in rice was similar in both geographical regions, and the aforementioned difference was attributed to dimethylarsinic acid (DMA). The relative abundance of organic species increased as the tAs content in rice grain increased. A meta-analysis of our and previously reported data confirmed the negative correlation between iAs/tAs and tAs. At low tAs concentrations, inorganic forms are dominant, while at higher values (tAs > 0.300 mg kg^-1) the concentration of organic As increases substantially and DMA becomes the dominant form in rice grain. On the contrary, inorganic arsenic was always the dominant form, mainly as arsenate [As(V)], in leaves and stems. The presence in soils of high concentrations of amorphous Fe and Al oxides and hydroxides, which are capable of strongly adsorbing oxyanions (i.e. arsenate), was associated with low concentrations of As in rice plants. In addition, the presence of high concentrations of As(V) in stems and leaves, low concentration of As in phytoliths, and the As associated with organic matter in stems and husk, together suggest that rice plants take up more As(V) than As(III).

Biochar-driven reduction of As(V) and Cr(VI): Effects of pyrolysis temperature and low-molecular-weight organic acids

Batch experiments were conducted to examine the differential effects of biochar pyrolysis temperature and low-molecular-weight organic acids on the reduction of As(V) and Cr(VI) driven by Pennisetum hydridum biochar. The results showed that pyrolysis temperature significantly affected the reducing strength of the biochar. Biochar produced at 500 °C had a stronger electron-donating capacity than did the biochars produced at 300 and 700 °C. In the co-presence of the biochar and a low-molecular-weight organic acid, arsenic and chromium behaved differently. Oxalic acid and malic acid tended to have better effects on enhancing biochar-driven Cr(VI) reduction, as compared to citric acid while the opposite was observed for biochar-driven As(V) reduction. Biochar produced at 300 °C was more favourable for Cr(VI) reduction, as compared to the higher-temperature biochars while the opposite was observed for As(V) reduction in the presence of low-molecular-weight organic acids. This may make the lower-temperature biochar ideal for remediating contaminated soils containing both As(V) and Cr(VI) since it could maximize Cr(VI) reduction while minimizing As(V) reduction.

Assessing inorganic arsenic in rice and its health risk to consumers in Ho Chi Minh City, Vietnam

Purpose

The consumption of rice that contains high levels of inorganic arsenic may cause human health risk. This study aims to determine As species concentrations, particularly iAs, in raw rice in Ho Chi Minh (HCM) City and its health risks.

Design/methodology/approach

A total of 60 polished raw composite samples of rice were purchased from traditional markets and supermarkets in HCM City. All samples were analyzed by HPLC-ICPMS for As species determination.

Findings

Mean concentrations of inorganic arsenic in all samples, which were purchased from supermarket and traditional market, were 88.8 µg/kg and 80.6 µg/kg, respectively. Overall, inorganic arsenic level was 84.7 µg/kg and contributed the highest proportion of arsenic species in rice with 67.7%. The proportion profiles for arsenic species were: As (III) (60 %); dimethylarsinic acid (32.2 %); As (V) (7.7 %) and methylarsonic acid (0.1 %). Inorganic arsenic level in raw rice was below the recommendation of World Health Organization. Using the benchmark dose recommended by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), all exposure doses were lower than BMDL05. However, as the doses ranged from 3.0 to 8.6 of Margin of Exposure (MOE), the health risk of iAs from rice consumption remains public health concern.

Originality/value

The study results report on the surveillance data of the presence of inorganic arsenic in raw rice products, which are available in the supermarkets and traditional markets, and its health risk to consumers in a metropolitan city in Vietnam.

Dietary exposure to arsenic and human health risks in western Tibet

The health effects of drinking water exposure to inorganic arsenic are well known but are less well defined for dietary exposure. The rising concerns of arsenic risks from diet motivated this study of arsenic concentrations in highland barley, vegetables, meat, and dairy products to evaluate arsenic exposure source and to assess health risks among rural residents of Ngari area, western Tibet. Total arsenic and arsenic speciation were measured by inductively coupled plasma mass spectrometry (ICP-MS) and high-performance liquid chromatography combined with ICP-MS (HPLC-ICP-MS) respectively. Average total arsenic concentrations of 0.18 ± 0.21 (n = 45, median: 0.07 mg·kg^-1), 0.40 ± 0.57 (n = 17, median: 0.15 mg·kg^-1), 0.21 ± 0.16 (n = 12, median: 0.17 mg·kg^-1), and 0.18 ± 0.08 (n = 11, median: 0.22 mg·kg^-1) were observed in highland barley, vegetables, meat, and dairy products, respectively. Inorganic arsenic was determined to be the main species of arsenic in highland barley, accounting for about 64.4 to 99.3% (average 83.3%) of total arsenic. Nearly half (44.4%) of the local residents had ingested >3.0 × 10^-4 mg·kg^-1·d^-1 daily dose of arsenic from highland barley alone, above the maximum oral reference dose recommended by the United States Environmental Protection Agency (USEPA). The inorganic arsenic daily intake from highland barley was 3.6 × 10^-4 mg·kg^-1·d^-1. Dietary exposure to inorganic arsenic alone increased the cancer risk probability to 5.4 in 10,000, assuming that the inorganic arsenic in highland barley has the same carcinogenic effects as that in water.

Public health risk of toxic metal(loid) pollution to the population living near an abandoned small-scale polymetallic mine

Small-scale mining activities in many developing countries have caused severe environmental issues to the surrounding areas, which ultimately threatened the health of local populations. Based on detailed characterization of the local drinking water and surface soil, as well as foodstuffs, this study comprehensively assessed the public health risk of toxic metal(loid)s to the population living in three villages surrounding an abandoned small-scale polymetallic mine in southern China. The agricultural soils contained elevated levels of Cu, Zn, As, Cd, and Pb, which originated from the mining district, and as expected, the locally cultivated rice and vegetables were contaminated by As, Cd, and Pb to varying extents. Arsenic occurred in both inorganic and organic forms in the rice and vegetables, with inorganic As (i-As) accounting for 82.2% (45.4-100%) and 94.7% (65.2-100%) of the total As contents in rice and vegetables, respectively. Results of health risk assessment indicate that the residents in the impacted villages had serious non-carcinogenic and carcinogenic risk. Dietary exposure to i-As and Cd through rice and vegetable consumption was the primary cause of non-carcinogenic risk, while i-As intake was the dominant contributor of carcinogenic risk. These findings suggest that significant environmental pollution by toxic metal(loid)s could result from small-scale metal mines, even after being abandoned, and the accumulation of the toxic metal(loid)s in food crops could pose significant health risk to the local residents. Immediate actions should be taken to discourage them from consuming the locally produced food crops, while long-term control measures for containment of toxic metal(loid) pollution are being developed, and high priority should be given to the remediation of Cd and As in the contaminated soils.

Soil arsenic but not rice arsenic increasing with arsenic in irrigation water in the Punjab plains of Pakistan

AIM

Irrigating rice with groundwater can lead to As accumulation in soil and rice grains. Matched sets of irrigation water, paddy soil, and rice grains were collected to assess the scale of the problem in the Punjab plains of Pakistan.

METHODS

From a total of 60 sites, irrigation water and rice grains as well as 103 soil samples were collected and analyzed in the laboratory. Irrigation water and 660 soil samples were also analyzed in the field using a field kit.

RESULTS

Concentrations of As in irrigation water (65±32 μg/L) are higher in the floodplain of the Ravi River compared to the Chenab (13±9 μg/L) and Jhelum (4±5 μg/L) rivers, as well as the intervening Rechna (6±6 μg/L) and Chaj doabs (0.8±0.2 μg/L). Area-weighted mean soil As concentrations are 12±3 mg/kg along the Ravi, 8.9±2 and 8.1±2 mg/kg along the Chenab and Jhelum, respectively, and 6.2±0.2 mg/kg within the Rachna and 6.1±0.1 mg/kg in Chaj doabs. The As content of polished grains export-quality basmati rice of 0.09±0.05 mg/kg, however, is low across the entire area.

CONCLUSIONS

Groundwater irrigation leads to elevated As concentrations in paddy soil of some rice-growing regions of Punjab but does not result in increased uptake of As in basmati rice grains.

Sulfate application decreases translocation of arsenic and cadmium within wheat (Triticum aestivum L.) plant

Arsenic (As) and cadmium (Cd) typically exhibit divergent fates in soil, which complicates efforts to decrease As and Cd accumulation in the edible parts of crops. Here, we performed pot experiments to examine the effect of sulfate application on As and Cd accumulation in the grain of wheat grown in contaminated soil. Compared to the control (no sodium sulfate addition), application of 120 mg kg^-1 sodium sulfate decreased the rhizosphere soil pH from 7.27 to 7.10 and increased the soil extractable Cd concentration; however, it did not significantly influence the soil extractable As concentration. However, sodium sulfate addition decreased As and Cd concentrations in wheat grain, in association with decreased As and Cd translocation from root and straw to grain, rather than from soil to root. Furthermore, sodium sulfate addition significantly decreased membrane lipid peroxidation and enhanced photosynthesis, while increasing the uptake of nitrogen, phosphorus, and sulfur. These effects increased the growth and grain weight of plants grown in As and Cd co-contaminated soil. Our findings provide insight into the mechanisms by which sulfate modulates As and Cd uptake and translocation in wheat; moreover, our findings will enable formulation of strategies to decrease As and Cd concentrations in the grain of wheat grown in As and Cd co-contaminated soil.

Effect of cooking on arsenic concentration in rice

This study assessed the effect of rinsing and boiling on total content of As (tAs) and of its inorganic and organic forms in different types of rice (polished and brown) from Spain and Ecuador. Rice was subjected to five different treatments. The results showed that the treatment consisting of three grain rinsing cycles followed by boiling in excess water showed a significant decrease in tAs content compared with raw rice. Regarding As species, it is worth noting that the different treatments significantly reduced the content of the most toxic forms of As. The estimated lifetime health risks indicate that pre-rinsing alone can reduce the risk by 50%, while combining it with discarding excess water can reduce the risk by 83%; therefore, the latter would be the preferable method.

Renal accumulation of prooxidant mineral elements and CKD in domestic cats

Felids have a high incidence of chronic kidney disease (CKD), for which the most common renal lesion is chronic interstitial nephritis (CIN). CIN can be induced by tissue oxidative stress, which is determined by the cellular balance of pro- and anti-oxidant metabolites. Fish-flavoured foods are more often fed to cats than dogs, and such foods tend to have higher arsenic content. Arsenic is a pro-oxidant metallic element. We propose that renal accumulation of pro-oxidant elements such as arsenic and depletion of anti-oxidant elements such as zinc, underpin the high incidence of CIN in domestic cats. Total arsenic and other redox-reactive metal elements were measured in kidneys (after acid-digestion) and urine (both by inductively-coupled plasma-mass spectrometry) of domestic cats (kidneys, n = 56; urine, n = 21), domestic dogs (kidneys, n = 54; urine, n = 28) and non-domesticated Scottish Wildcats (kidneys, n = 17). Renal lesions were graded by severity of CIN. In our randomly sampled population, CIN was more prevalent in domestic cat versus domestic dog (51%, n = 32 of 62 cats; 15%, 11 of 70 dogs were positive for CIN, respectively). CIN was absent from all Scottish wildcats. Tissue and urinary (corrected for creatinine) arsenic content was higher in domestic cats, relative to domestic dogs and wildcats. Urine arsenic was higher in domestic cats and dogs with CIN. Arsenobetaine, an organic and relatively harmless species of arsenic, was the primary form of arsenic found in pet foods. In summary, the kidneys of domestic cats appear to have greater levels of pro-oxidant trace elements, as compared to dogs and wildcats. Since there was no difference in renal arsenic levels in cats with or without CIN, renal arsenic accumulation does not appear a primary driver of excess CIN in cats. Given clear differences in renal handling of pro vs. anti-oxidant minerals between cats and dogs, further in vivo balance studies are warranted. These may then inform species-specific guidelines for trace element incorporation into commercial diets.

Wheat is an emerging exposure route for arsenic in Bihar, India

In arsenic (As) endemic areas of south-east Asia, where a subsistence rice-based diet is prevalent, As exposure from food is mainly focused on rice intake. However, consumption of wheat is substantial and increasing. We present a probabilistic assessment of increased cancer risk from wheat-based food intake in a study population of rural Bihar, India where As exposure is endemic. Total As in wheat grains (43.64 ± 48.19 µg/kg, n = 72) collected from 77 households across 19 villages was found to be lower than reported As in wheat grains from other south-east Asian countries but higher than a previous study from Bihar. This is the first study where As concentration in wheat flour was used for risk estimation, bearing in mind that it was the flour obtained after indigenous household processing of the grains that was used for making the home-made bread (chapati) which contributed 95% of wheat intake for the studied population. Interestingly, while 78% of the surveyed participants (n = 154) consumed rice every day, chapati was consumed every day by 99.5% of the participants. In contrast to previous studies, where As concentration in wheat grains was found to be lower than the flour due to the removal of the bran on grinding, we did not find any appreciable lowering of arsenic in the wheat flour (49.80 ± 74.08 µg/kg, n = 58), most likely due to external contamination during processing and grinding. Estimated gender adjusted excess lifetime cancer risk of 1.23 × 10^-4 for the studied rural population of Bihar indicated risk higher than the 10^-4-10^-6 range, typically used by the USEPA as a threshold to guide regulatory values. Hence, our findings suggest As exposure from wheat-based food intake to be of concern not only in As endemic areas of rural Bihar but also in non-endemic areas with similar wheat-based diet due to public distribution of the wheat across India.

An assessment of arsenic hazard in groundwater-soil-rice system in two villages of Nadia district, West Bengal, India

The present study measured arsenic (As) concentrations in soil, groundwater and rice grain samples in two villages, Sarapur and Chinili, under Chakdaha block, Nadia district, West Bengal, India. This study also included a survey of the two villages to understand the knowledge among villagers about the As problem. Soil and groundwater samples were collected from fields in two villages while rice grain samples were collected from villagers' houses. The results revealed the presence of As in higher concentrations than the maximum permissible limit of As in drinking water (10 µg L^-1 and 50 µg L^-1 by WHO and Indian standard, respectively) in groundwater [124.50 ± 1.11 µg L^-1 (Sarapur) and 138.20 ± 1.34 µg L^-1 (Chinili)]. The level of As in soil was found to range from 47.7 ± 0.14 to 49.3 ± 0.19 mg Kg^-1 in Sarapur and from 57.5 ± 0.25 to 62.5 ± 0.44 mg Kg^-1 in Chinili which are also higher than European Union maximum acceptable limit in agricultural soil (i.e. 20 mg Kg^-1). The analysis of As in rice grains of five varieties, collected from residents of two villages, showed the presence of higher than recommended safe level of As in rice by FAO/WHO (0.2 mg Kg^-1). The As concentration order was Gosai (0.95 ± 0.044 mg kg^-1), Satabdi (0.79 ± 0.038 mg kg^-1), Banskathi (0.60 ± 0.026 mg kg^-1), Kunti (0.47 ± 0.018 mg kg^-1) and Ranjit (0.29 ± 0.021 mg kg^-1). Importantly, Gosai and Satabdi were the most popular varieties being consumed by local people. The data of consumption of rice per day in the survey was used for the measurement of average daily dose and hazard quotient. It was seen that the As hazard was negatively correlated to the age of residents. Therefore, children and toddlers were at higher risk of As exposure than elderly people. In addition, people with skin related As toxicity symptoms were also cited in the two villages. The study emphasized the severity of As problem in remote areas of West Bengal, India where people consume As tainted rice due to lack of awareness about the As problem and associated health issues.

A deterministic and stochastic assessment for exposure and risk of arsenic via ingestion of edible crops

Natural arsenic contamination is a critical problem for various places around the world. Simav Plain (Kutahya, Turkey) is one such area that was shown to have natural arsenic contamination in its waters and soils. Arsenic exposure through ingestion of edible crops cultivated in Simav Plain and associated health risks were assessed in this study. To achieve this objective, arsenic levels in 18 crop species were estimated based on measured soil arsenic concentrations. Individual and aggregate non-carcinogenic and carcinogenic risks associated with ingestion of arsenic-contaminated crops were then assessed with scenario-based deterministic point estimates and stochastic population estimates. Monte Carlo simulation was used for the estimation of population health risks. Accordingly, wheat was found as the highest-ranked crop specie for the both types of health risks, followed by tomato and potato, which are three of the most consumed crops in the region. The risk levels estimated in this study were relatively high, indicating consumption of crops grown in the plain may be posing significant health risks even at lower-bound estimates. Consuming wheat, tomato, potato, and their products from uncontaminated sources was found to reduce the aggregate risks up to 88% implicating the importance of proposing suitable management measures for similar risk-prone areas.

Accumulation and distribution of arsenic and cadmium in winter wheat (Triticum aestivum L.) at different developmental stages

Arsenic (As) and cadmium (Cd) are known to be toxic to humans, and elevated concentrations have been documented in food crops worldwide. However, little is known regarding their uptake, translocation, and distribution in wheat plants during plant development. A series of experiments were conducted to investigate the spatial distribution and dynamics of As and Cd in two wheat cultivars (cv. JN12 and JM85; the latter is a low grain Cd accumulator) at different developmental stages. Root concentrations of As decreased by 84%, and those of Cd by 67%, from tillering to maturity. In contrast, As concentrations in the stems increased 3.1-fold. A significant decrease in root As accumulation was observed at the mature stage, whereas root Cd accumulation decreased largely at the elongation stage. The concentrations of Cd in all leaves and As in new leaves increased as plant growth advanced. However, As concentrations in old leaves decreased significantly from grain filling to maturity. In both cultivars, the upward transfer toward younger parts of shoots was greater in the case of Cd than of As. The remobilization of As and Cd from stems and roots differed between the two cultivars. Arsenic concentrations in rachis, glumes, and grain in JM85 were significantly higher than those in JN12, whereas As concentrations in roots and stems did not differ between the cultivars. Grain Cd was significantly higher in JN12 than in JM85, but Cd concentrations in rachis and glumes were similar between the cultivars. The difference in grain Cd concentration between the two cultivars depended on root and stem Cd remobilization and redistribution from rachis to glumes and grain; in contrast, accumulation of As in grain was influenced by As remobilization from the leaves and stem to the spike.

Arsenic Contamination and Associated Health Risk (Brief Review)

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

Speciation Analysis of Arsenic Compounds by High-Performance Liquid Chromatography in Combination with Inductively Coupled Plasma Dynamic Reaction Cell Quadrupole Mass Spectrometry: Application for Vietnamese Rice Samples

In this work, high-performance liquid chromatography in combination with inductively coupled plasma dynamic reaction cell quadrupole mass spectrometry was introduced and optimized for speciation analysis of five major arsenic species including arsenobetain (AsB), arsenite (As(III)), monomethylarsonic (MMA), dimethylarsenonic acid (DMA), and arsenate (As(V)) in rice samples. Five arsenic compounds were separated on a Hamilton PRP X100 strong anion-exchange column employed with the mobile phase that is compatible with mass spectrometry, containing ammonium carbonate, methanol, and disodium ethylenediaminetetraacetic acid. Arsenic compounds were detected online by inductively coupled plasma dynamic reaction cell quadrupole mass spectrometry utilizing oxygen as the reaction gas at a flow rate of 0.7 mL·min^-1. Five selected arsenic species were baseline separated at the optimum experimental conditions. The excellent LOD and LOQ values of the developed method were achieved in the range of 0.5 to 2.9 μg·kg^-1 and 1.7 to 9.6 μg·kg^-1 for all species of arsenic, respectively. The ionization effect in plasma during chromatographic gradient elution was systematically investigated by using postcolumn injector. Arsenic compounds in rice samples were extracted by diluted nitric acid at elevated temperature. The extraction efficiency and the interconversion of target compounds during sample preparation were also assessed. The full validation of the developed method was performed by using certified reference material, BRC 211, from European Institute of Reference and Standard for speciation analysis. The recovery of all selected arsenic species was in the range of 70 to 135.5%. The validated method was also applied to analyze rice samples collected from some contaminated rice fields. The results showed that As(III), DMA, and As(V) were found in all rice samples. Average concentration (range) of inorganic arsenic and DMA in all rice samples were 130.3 (65.5-228.1) and 32 (8.2-133.01) μg·kg^-1, respectively. However, total concentration of inorganic arsenic in most of investigated rice samples was below the maximum residual level according to US-FDA and European Union standards.