Extraction and determination of arsenic species in leafy vegetables: Method development and application

Dominant role of soil iron and organic matters in arsenic transfer from soil to plant in a mine area in Hunan Province, Central China

The transfer of arsenic (As) from soil to plant could be significantly influenced by soil parameters through regulating soil As bioavailability. To distinguish the bioavailable As provided by soil and the As uptaken by plants, herein two different soil bioavailable were defined, namely potential soil bioavailable As (evaluated through the bioavailable fraction of As) and actual soil bioavailable As (assessed through plant bioaccumulation factor, BF, and BFavailable). To identify the dominant soil parameters for the two soil bioavailable As forms, soil and plant samples were collected from a former As mine site. The results showed that the potential bioavailable As only accounted for 1.77 to 11.43% in the sampled soils, while the BF and BFavailable in the sampled vegetables ranged from 0.00 to 1.01 and 0.01 to 17.87, respectively. Despite a similar proportion of As in the residual fraction, soil with higher pH and organic matter (OM) content and lower iron (Fe) content showed a higher potential soil bioavailable As. Correlation analysis indicated a relationship between the soil pH and potential soil bioavailable As (r = 0.543, p < 0.01) and between the soil Fe and actual soil bioavailable As (r =  - 0.644, p < 0.05, r =  - 0.594, p < 0.05). Stepwise multiple linear regression (SMLR) analysis was employed to identify the dominant soil parameters and showed that soil pH and phosphorus (P) content could be used to predict the potential soil bioavailable As (R2 = 0.69, p < 0.001). On the other hand, soil Fe and OM could be used to predict the actual soil bioavailable As (R2 = 0.18-0.86, p < 0.001-0.015, in different vegetables). These results suggest that different soil parameters affect potential and actual soil bioavailable As. Hence, soil Fe and OM are the most important parameters controlling As transfer from soil to plant in the investigated area.

Unveiling New Arsenic Compounds in Plants via Tailored 2D-RP-HPLC Separation with ICP and ESI MS Detection

Arsenic (As) speciation analysis is scientifically relevant due to the pivotal role the As chemical form plays in toxicity, which, in turn, directly influences the effect it has on the environment. The objective of this study was to develop and optimize a method tailored for studying As compounds in plant samples. Different extraction procedures and HPLC methods were explored to assess their efficiency, determine mass balance, and improve the resolution of compounds in the chromatograms. Conventionally applied anion-exchange chromatography facilitated the separation of well-documented As compounds in the extracts corresponding to 19 to 82% of As present in extracts. To gain insight into compounds which remain undetectable by anion chromatography (18 to 81% of As in the extracts), but still possibly metabolically relevant, we explored an alternative chromatographic approach. The procedure of sample purification and preconcentration through solid-phase extraction, facilitating the detection of those minor As compounds, was developed. The system was further refined to achieve an online 2D-RP-HPLC system, which was employed to analyze the extracts more comprehensively with ICP and ESI MS. Using this newly developed method, As(III)-phytochelatins, along with other arseno-thio-compounds, were detected and identified in extracts derived from the tree roots of seedlings grown in the presence of As(III) and As(V), and a group of arseno lipids was detected in the roots of plants exposed to As(V).

Pollution characteristics and prospective risk of microplastics in the Zhengzhou section of Yellow River, China

The ubiquitous occurrence of microplastics (MPs) in the freshwater has attracted widespread attention. The Zhengzhou section of the Yellow River was the most prosperous region in ancient China, and the rapid urbanization, industrialization, and agricultural practices contributed to MPs pollution in aquatic systems recently, whereas the contamination status of MPs in the area is still not available. In this study, a total of fourteen sampling cross-sections were selected in the region to collect water samples systematically for the analysis of MPs pollution characteristics and potential risks. Results showed that abundance of MPs in the water were ranged from 2.33 to 15.50 n/L, with an average value of 6.40 ± 3.40 n/L, which was higher than it in other inland rivers from China. Moreover, the MPs of 0.5-2 mm were the dominant sizes in Yellow River of Zhengzhou region, and most of them were black fibres. The top three polymers were Polyethylene terephthalate (PET), Polyamide (PA) and Polypropylene (PP). High diversity indices of MPs observed at S3, S4, S5, S6, S7, and S8 for size, colour, polymer and shape indicated diverse and complex sources of MPs in those cross-sections. The MPs in water from Zhengzhou area of Yellow River probably degraded from textiles, fishing net, plastic bags, mulching film, packaging bags, and tire wear. The chemical risk assessment revealed a level III risk for study area, while S8 and S11 in which PVA or PAN with higher hazard score detected were categorised as class V risk. Coincidentally, probabilistic risk assessment showed a considerable ecological risk of MPs from Yellow River in Zhengzhou City, with possibility of 99.48 and 98.01 % adverse effect for food dilution and translocation-mediated mechanism, respectively. The results are expected to assistance for development of policies and ultimately combating MPs pollution.

Assessment of health risks associated with prediction of vegetable inorganic arsenic concentrations given different soil properties

Inorganic arsenic (iAs) is a carcinogen. Vegetables such as water spinach (Ipomoea aquatica Forssk.) and amaranth (Amaranthus mangostanus L.) are recognized as high-risk sources of iAs exposure because they can accumulate significant amounts of iAs and are widely consumed. To ensure safe cultivation conditions, this study aimed to establish prediction models for iAs concentration in the edible parts of water spinach and amaranth based on soil properties. Subsequently, health risk assessments associated with iAs exposure through the consumption of these vegetables were conducted using prediction models. Soil samples were collected from agricultural fields in Taiwan and used in the pot experiments. Pearson correlation and partial correlation analyses were used to explore the relationship between soil properties, including total As, clay, organic matter, iron oxides and available phosphates, and iAs concentration in edible parts of water spinach and amaranth. Prediction models based on soil properties were developed by stepwise multiple linear regression. Health risk assessments were conducted using the Monte Carlo algorithm. The results indicate that total As and organic matter contents in soil were major predictors of iAs concentration in water spinach, whereas those in amaranth were total As and clay contents. Therefore, higher health risks for consuming water spinach and amaranth are associated with higher levels of organic matter and clay contents in soil, respectively, and these are crucial factors to consider to ensure food safety. This study suggested that As-elevated soils enriched with organic matter and clay contents should be avoided when growing water spinach and amaranth, respectively.

Toxicity, arsenic speciation and characteristics of hyphenated techniques used for arsenic determination in vegetables. A review

Arsenic (As) speciation is an interesting topic because it is well recognized that the toxicity of this metalloid ultimately depends on its chemical form. More than 300 arsenicals exist naturally. However, As can be present in four oxidation states: As-III, As0, AsIII and AsV. Long-term exposure to As from different sources, such as anthropogenic processes, or water, fauna and flora contaminated with As, has put human health at risk for decades. There are many side-effects correlated with exposure to InAs species, such as skin problems, respiratory diseases, kidney problems, cardiovascular diseases and even cancer. There are different levels and types of As in foods, particularly in vegetables. Furthermore, different chemical methods and techniques have been developed. Therefore, this review focuses on the general properties of various approaches used to identify As species in vegetation samples published worldwide. This includes various approaches (different solvents and techniques) used to extract As species from the matrix. Then, versatile chromatographic and non-chromatographic systems to separate different forms of As are reviewed. Finally, the general properties of the most common instruments used to detect As species from samples of interest are listed.

Effects of Transporter Inhibitors and Chemical Analogs on the Uptake of Antimonite and Antimonate by Boehmeria nivea L

Antimony (Sb) is a non-essential metalloid that can be taken up by plants from contaminated soils and thus enter the food chain and threaten human health. Boehmeria nivea L. (ramie) is a promising phytoremediation plant for Sb-polluted soils. However, the mechanisms of antimonite (SbIII) and antimonate (SbV) uptake by ramie remain unclear. In this study, a hydroponic system was established to investigate how different substances affect the uptake of SbIII or SbV by ramie, including an energy inhibitor (malonic acid), an aquaglyceroporin inhibitor (silver nitrate), an SbV analog (phosphate-PV), and SbIII analogs (arsenite-AsIII, glycerol, silicic acid-Si, and glucose). The results indicated that ramie primarily transported Sb by increasing the Sb concentration in the bleeding sap, rather than increasing the weight of the bleeding sap. After 16 h of Sb exposure, the absolute amount of transported Sb from the roots to the aboveground parts was 1.90 times higher under SbIII than under SbV. The addition of malonic acid significantly inhibited the uptake of SbV but had limited effects on SbIII, indicating that SbV uptake was energy dependent. PV addition significantly reduced SbV uptake, while the addition of AsIII, glycerol, and Si obviously inhibited SbIII uptake. This suggested that the uptake of SbV might be via low-affinity P transporters and SbIII might use aquaglyceroporins. These findings deepen the understanding of Sb uptake pathways in ramie, contribute to a better comprehension of Sb toxicity mechanisms in ramie, and establish a foundation for identifying the most effective Sb uptake pathways, which could further improve the efficiency of phytoremediation of Sb-polluted soils.

Advancing herbal medicine: enhancing product quality and safety through robust quality control practices

This manuscript provides an in-depth review of the significance of quality control in herbal medication products, focusing on its role in maintaining efficiency and safety. With a historical foundation in traditional medicine systems, herbal remedies have gained widespread popularity as natural alternatives to conventional treatments. However, the increasing demand for these products necessitates stringent quality control measures to ensure consistency and safety. This comprehensive review explores the importance of quality control methods in monitoring various aspects of herbal product development, manufacturing, and distribution. Emphasizing the need for standardized processes, the manuscript delves into the detection and prevention of contaminants, the authentication of herbal ingredients, and the adherence to regulatory standards. Additionally, it highlights the integration of traditional knowledge and modern scientific approaches in achieving optimal quality control outcomes. By emphasizing the role of quality control in herbal medicine, this manuscript contributes to promoting consumer trust, safeguarding public health, and fostering the responsible use of herbal medication products.

Extraction methods optimization of available heavy metals and the health risk assessment of the suburb soil in China

Heavy metal pollution has attracted increasing concern due to its high toxicity and persistence. A suitable extraction procedure for available heavy metals in soil is necessary for assessing the ecological risk. In this work, the single extraction methods aided by shaking and microwaves were investigated and analyzed for their ability to extract available heavy metals from soil samples, and a total of 42 soil samples were collected from suburbs of Zhengzhou city in China. The extraction efficiency of Cu, Zn, As, and Cd in the certified fluvo-aquic soil was compared using eight different types of solutions: CaCl2, CH3COONH4, NH4NO3, CH3COOH, Na2EDTA, DTPA, HNO3, and NH4H2PO4. Results indicated that the shaking-assisted method that utilized Na2EDTA as an extractant demonstrated satisfactory efficiency and was chosen for further optimization and that the optimal conditions were obtained using 0.05 M Na2EDTA at pH 7, soil-liquid ratio 1:20, and extraction duration 2 h, which gained the perfect extraction efficiency ranging from 85.8 to 109.5%. The proposed approach has been applied to extract available Cu, Zn, As, and Cd in soils of Zhengzhou suburbs, where the mean values varied from 0.129 to 6.881 mg/kg. The bioavailability of different heavy metals in the soil varies greatly, with Cd having the highest activity in the survey region. Significant (p < 0.01) positive relationships were observed between the available state and the total amount of all the heavy metals. The assessment of health risks associated with heavy metals indicated that there was no risk for chronic non-carcinogenic effects. Even though the total amount of metal elements in suburban soil of Zhengzhou is 1.6% with high carcinogenic risk, the risk of available elements is still within the acceptable range, which verified that the risk grade obtained by the total amount is higher than the actual risk.

Association between mediterranean diet and metal(loid) exposure in 4-5-year-old children living in Spain

Even relatively low levels of metals exposure may impact health, particularly among vulnerable populations such as infants and young children. However, little is known about the interplay between simultaneous metal exposures, common in real-life scenarios, and their association with specific dietary patterns. In this study, we have evaluated the association between adherence to Mediterranean diet (MD) and urinary metal concentrations individually and as an exposure mixture in 713 children aged 4-5-years from the INMA cohort study. We used a validated food frequency questionnaire to calculate two MD indexes scores: aMED and rMED. These indexes gather information on various food groups within the MD and score differently. To measure urinary concentrations of cobalt, copper, zinc, molybdenum, selenium, lead, and cadmium as exposure biomarkers, we used inductively coupled plasma mass spectrometry (ICP-MS), coupled with an ion chromatography (IC) equipment for arsenic speciation analysis. We applied linear regression and quantile g-computation, adjusted for confounders, to analyse the association between MD adherence and exposure to the metal mixture. High adherence to MD such as the quintile (Q) 5 MD was associated with higher urinary arsenobetaine (AsB) levels than Q1, with β values of 0.55 (confidence interval - CI 95% 0.01; 1.09) for aMED and 0.73 (CI 95% 0.13; 1.33) for rMED. Consumption of fish was associated with increased urinary AsB but reduced inorganic arsenic concentrations. In contrast, the aMED vegetables consumption increased urinary inorganic arsenic content. A moderate level of adherence to MD (Q2 and Q3) was associated with lower copper urinary concentrations than Q1, with β values of -0.42 (CI 95% -0.72; -0.11) for Q2 and -0.33 (CI 95% -0.63; -0.02) for Q3, but only with aMED. Our study, conducted in Spain, revealed that adhering to the MD reduces exposure to certain metals while increasing exposure to others. Specifically, we observed increase in exposure to non-toxic AsB, highlighting the significance of consuming fish/seafood. However, it is crucial to emphasize the necessity for additional efforts in reducing early-life exposure to toxic metals, even when adhering to certain food components of the MD.

Detoxification and removal of arsenite by Pseudomonas sp. SMS11: Oxidation, biosorption and bioaccumulation

Arsenite [As(III)] oxidizing bacteria have been widely studied for their detoxification ability through transforming As(III) into arsenate [As(V)]. However, few was focused on removal capacity of arsenic (As). In the current study, As(III) oxidation accompanied with removal of total As was observed in Pseudomonas sp. SMS11. The biosorption (unbinding and surface binding) and bioaccumulation (intracellular uptake) of As by the cells were investigated. Biosorption isotherm was defined adequately by Langmuir and Freundlich models. Biosorption kinetics was recommended by pseudo second-order model. For comparison, the bacteria were inoculated in pure water or culture media amended with different concentrations of As(III) to evaluate the remediation capacity without or with bacterial growth. After removing unbound As, surface bound and intracellular As were sequentially separated using EDTA elution and acidic extraction from bacterial cells. Without bacterial growth, oxidation of As(III) was retarded and the maximum values of surface bound and intracellular As were 4.8 and 10.5 mg/g, respectively. Efficient oxidation and high adsorption capacity were observed after bacterial growth. The surface bound and intracellular As achieved up to 555.0 and 2421.5 mg/g, respectively. Strain SMS11 exhibited great accumulation capacity of As in aqueous solutions, indicating potential application in detoxification and removal of As(III) contamination. The results also suggested that bioremediation via bacteria should be based on living cells and bacterial growth rate.

Transcriptomic analysis reveals the molecular mechanisms of Boehmeria nivea L. in response to antimonite and antimonate stresses

Soil antimony (Sb) pollution is a global concern that threatens food security and human health. Boehmeria nivea L. (ramie) is a promising phytoremediation plant exhibiting high tolerance and enrichment capacity for Sb. To reveal the molecular mechanisms and thus enhance the ramie uptake, transport, and detoxification of Sb with practical strategies, a hydroponic experiment was conducted to compare the physiological and transcriptomic responses of ramie towards antimonite (Sb(Ⅲ)) and antimonate (Sb(Ⅴ)). Phenotypic results showed that Sb(Ⅲ) had a stronger inhibitory effect on the growth of ramie. Root Sb content under Sb(Ⅲ) was 2.43 times higher than that in Sb(Ⅴ) treatment. Based on the ribonucleic acid sequencing (RNA-Seq) technique, 3915 and 999 significant differentially expressed genes (DEGs) were identified under Sb(Ⅲ) and Sb(Ⅴ), respectively. Transcriptomic analysis revealed that ramie showed different adaptation strategies to Sb(Ⅲ) and Sb(V). Key DEGs and their involved pathways such as catalytic activity, carbohydrate metabolisms, phenylpropanoid biosynthesis, and cell wall modification were identified to perform crucial roles in Sb tolerance and detoxification. Two heavy metal-associated domain-type genes, six heavy metal-associated isoprenylated plant proteins, and nine ABC transporters showed possible roles in the transport and detoxification of Sb. The significant upregulation of NRAMP5 and three NIPs suggested their roles in the transport of Sb(V). This study is the basis for future research to identify the exact genes and biological processes that can effectively enhance Sb accumulation or improve plant tolerance to Sb, thereby promoting the phytoremediation of Sb-polluted soils.

Uptake, tolerance, and detoxification mechanisms of antimonite and antimonate in Boehmeria nivea L

Boehmeria nivea L. (ramie) is a promising phytoremediation plant for antimony (Sb)-contaminated soils. However, the uptake, tolerance, and detoxification mechanisms of ramie to Sb, which are the basis for finding efficient phytoremediation strategies, remain unclear. In the present study, ramie was exposed to 0, 1, 10, 50, 100, and 200 mg/L of antimonite (Sb(III)) or antimonate (Sb(V)) for 14 days in hydroponic culture. The Sb concentration, speciation, subcellular distribution, and antioxidant and ionomic responses in ramie were investigated. The results illustrated that ramie was more effective in the uptake of Sb(III) than Sb(V). Most of the Sb accumulated in ramie roots, with the highest level reaching 7883.58 mg/kg. Sb(V) was the predominant species in leaves, with 80.77-96.38% and 100% in the Sb(III) and Sb(V) treatments, respectively. Immobilization of Sb on the cell wall and leaf cytosol was the primary mechanism of accumulation. Superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) contributed significantly to root defense against Sb(III), while CAT and glutathione peroxidase (GPX) were the major antioxidants in leaves. CAT and POD played crucial roles in the defense against Sb(V). B, Ca, K, Mg, and Mn in Sb(V)-treated leaves and K and Cu in Sb(III)-treated leaves may be related to the biological processes of Sb toxicity mitigation. This study is the first to investigate the ionomic responses of plants toward Sb and could provide valuable information for the phytoremediation of Sb-polluted soils.

Coupling phytotoxicity and human health risk assessment to refine the soil quality standard for As in farmlands

In the present study, a field experiment was conducted to investigate arsenic (As) concentrations in soils and in grains of 15 rice varieties in a contaminated site in Taiwan. The studied site was divided into two experimental units, namely plot A and plot B. The results showed that mean total As concentrations were 70.94 and 61.80 mg kg^-1 in plot A and plot B, respectively, and thus greater than or approximate to the soil quality standard for total As in Taiwan (60 mg kg^-1). The As levels in rhizosphere soil in plot A (19.71-32.33 mg kg^-1) were much higher than in plot B (6.41-8.60 mg kg^-1); however, As accumulation in brown rice did not significantly differ between the plots. These results implied that a significant variation in the bioconcentration factor (BCF) value of As existed among different rice genotypes, and a negative correlation was observed between BCF value and rhizosphere As level in the soil. In phytotoxicity, the median values of the ecological risk indicator were 104.85 and 103.89 in plot A and plot B, respectively, indicating considerable risk. In human health risk assessment, the median and 97.5%-tile values for cancer risk for both male and female residents were markedly higher than the acceptable risk (1 × 10^-4). Furthermore, non-cancer and cancer risks were higher for males than females, mainly due to the greater rice ingestion rate of males. Sensitivity analysis showed that total As concentration in soil was the main factor affecting health risks, suggesting that priority should be given to the reduction of soil As levels. To better manage the phytotoxicity of As on rice, as well as the health risk to residents resulting from exposure to As-contaminated soils, the soil quality standard for As in farmland soils should be set between 5 and 10 mg kg^-1. The methodology developed in this study could also be applied to provide the basis for refining and revising the soil quality standard for heavy metals in farmland in other regions and countries.

Characterization and Quantification of Arsenic Species in Foodstuffs of Plant Origin by HPLC/ICP-MS

Arsenic is a well-known carcinogenic, mutagenic and toxic element and occurs in the environment both as inorganic arsenic (iAs) and organoarsenical compounds (oAsCs). Since the toxicity of arsenic compounds depends on their chemical form, the identification and determination of arsenic species are essential. Recently, the European Food Safety Authority, following the European Commission request, published a report on chronic dietary exposure to iAs and recommended the development and validation of analytical methods with adequate sensitivity and refined extraction procedures for this determination. Moreover, the authority called upon new arsenic speciation data for complex food matrices such as seaweeds, grains and grain-based products. Looking at this context, an optimized, sensitive and fast analytical method using high performance liquid chromatography followed by inductively coupled plasma-mass spectrometry (HPLC/ICP-MS) was developed for the determination of iAs (sum of arsenite-As^III and arsenate-As^V) and the most relevant oAsCs, arsenobetaine, dimethylarsinic acid and monomethylarsonic acid. The method was validated with satisfactory results in terms of linearity, sensitivity, selectivity, precision, recovery, uncertainty, ruggedness and matrix effect, and then successfully applied for the analysis of several matrices, i.e., processed and unprocessed cereal and cereal products, fruits, vegetables, legumes, seaweeds, nuts and seeds. The results obtained indicate that not only seaweed and rice matrices but also many cereals, legumes and plant-based foods for infants and young children contain significant concentrations of iAs and oAsCs. These findings contribute to the data collection necessary to assess the role of these matrices in the total arsenic exposure and if specific maximum limits have to be established.

Use of compost in the uptake mitigation of arsenic in Beta vulgaris L. var. cicla

BACKGROUND

Arsenic (As) may represent a risk for crop yield quality and human health since it may accumulate in the edible plant organs with the potential of leading to acute or chronic toxic effects in varied segments of the population. Management of soil fertility through compost has proven to be a valuable practice for increasing and maintaining soil organic matter, with nutritional benefits for crops. This work aimed to evaluate Swiss chard yield and the change in the bioavailability, bioaccumulation, and partitioning of As in the response of the use of compost or conventional mineral fertilization in an open-field trial conducted in a volcanic area in central Italy characterized by the natural contamination of As in soil.

RESULTS

Compost treatment led to a short-term increase trend in soil organic carbon, total nitrogen, and available phosphorus in a significant way. In the compost-amended plots, the mitigation of the As uptake was detected in leaves, which are the edible part of Swiss chard. The As bioaccumulation factor in leaves of Swiss chard and the translocation factor for leaves/roots were also decreased using compost.

CONCLUSION

Fertilization by compost can improve soil fertility, sustain Swiss chard production, and mitigate As accumulation in leaves of this crop grown in a naturally As-contaminated soil. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Field experiments for evaluating the effects of water management and phosphate application on inorganic arsenic accumulation in water spinach (Ipomoea aquatica Forssk.)

Water spinach (Ipomoea aquatica Forssk.) is a commonly planted vegetable in the Southeast Asia; it is a semi-aquatic leafy vegetable with high inorganic arsenic (As) accumulation capability and can be planted under both upland and flooding cultivation conditions. To date, a limited number of field studies have investigated the effect of soil management on As phytotoxicity and accumulation of water spinach. Therefore, in this study, a field experiment was conducted to investigate the effects of water management and phosphate (P) application on the As phytotoxicity and accumulation of water spinach grown in As-contaminated fields (121 mg As kg^-1). Water spinach was planted in the study field with two water management (flooding and upland cultivation) and two P application rates (90 and 180 kg P₂O₅ ha^-1), and continuously harvested three times. Results reveal that the concentration and estimated daily intake (EDI) of inorganic As in the edible parts of water spinach under flooding cultivation were approximately twofold higher than those under upland cultivation. It was also found that the accumulation of As in the shoot of water spinach was strongly related to the As concentrations, rather than P/As molar ratio in pore water due to that P application rates were lower than the maximum capacity for P retention of the tested soil. Moreover, the As phytotoxicity and accumulation of water spinach were reduced at the third harvest relative to the first two harvests because of the increase in iron plaque formation on the root surface and the decrease in the growing temperature during the experimental period. Our results suggest that upland cultivation is the better practice than flooding cultivation for reducing inorganic As accumulation in the edible parts of water spinach grown in As-contaminated soils. Further, ratooning may be a feasible cultivation approach to reducing inorganic As accumulation in water spinach.

Occurrence, accumulation, and health risks of heavy metals in Chinese market baskets

Residual levels and accumulation characteristics of six hazardous heavy metal elements (As, Cd, Hg, Tl, Pb, and U) and seven essential heavy metal elements (Cr, Mn, Fe, Ni, Cu, Zn, and Se) were investigated in 17 kinds of frequently consumed foodstuffs collected from 33 cities distributed in five regions of China. The concentrations of the detected metals were lower than the maximum limits promulgated by the Chinese government except Pb and inorganic As (iAs). Foods of aquatic origin and terrestrial plant origin exhibited high potentials to accumulate heavy metals, especially algae and shellfish. The calculated hazard index (HI) of heavy metal exposure via consumption of foodstuffs were 2.93-5.01 for adults in the five surveyed region, implying the co-exposure of heavy metals via food consumption would lead to potential non-carcinogenic risks. iAs was the predominant contributor to HI values with the average contribution of 40.5% in all five regions. Consumption of terrestrial plant origin foods contributed 76.9% of HI values induced by heavy metal exposure. The calculated target cancer risks of iAs in the five regions were 5 × 10^-4-1 × 10^-3, all exceeding the acceptable level of 10^-4, indicating it is necessary and urgent to reduce the contamination of iAs in foodstuffs on the Chinese markets.

Comparative evaluation of in vivo relative bioavailability and in vitro bioaccessibility of arsenic in leafy vegetables and its implication in human exposure assessment

Arsenic (As) contamination in vegetables is a severe threat to human health. However, the evaluation of As relative bioavailability (As-RBA) or bioaccessibility in vegetables is still unexplored. The study sought to evaluate the As-RBA in commonly consumed ten leaf vegetables collected from As-polluted farmlands. Additionally, the As-RBA was determined using rat bioassay and compared with As bioaccessibility through five commonly used in vitro methods, including UBM (Unified BARGE Method), SBRC (Solubility Bioavailability Research Consortium), DIN (Deutsches Institut für Normung e.V.), IVG (In Vitro Gastrointestinal), and PBET (Physiologically Based Extraction Test). Results showed that the As-RBA values were 14.3-54.0% among different vegetables. Notably, significant in vivo-in vitro correlations (IVIVC) were observed between the As-RBA and the As bioaccessibility determined by the PBET assay (r² = 0.763-0.847). However, the other assays (r² = 0.417-0.788) showed a comparatively weaker relationship. The estimation of As-RBA using derived IVIVC to assess As exposure risk via vegetable consumption confirmed that As exposure risk based on As-RBA was lower than that the total As concentrations. Therefore, it was concluded that PBET could better predict the As-RBA in vegetables than other in vitro assays. Furthermore, As-RBA values should be considered for accurate health risk assessment of As in vegetables.

Comparison of As accumulation and speciation in water spinach (Ipomoea aquatica Forssk.) grown in As-elevated soils under flooding versus upland conditions

Water spinach (Ipomoea aquatica Forssk.) is a popular semi-aquatic vegetable with high arsenic (As) accumulation capability in tropical and subtropical areas, and it can grow under both flooding and upland conditions. Because only few studies addressed the dietary As risk of vegetable consumption, this study investigated the accumulation and speciation of As in the water spinach, and the human health risk of consuming this crop grown in different water managements. Pot experiments were conducted in two soils with different As levels under both flooded and upland conditions. The results showed that As concentrations, mainly inorganic As, in soil pore water and shoots under flooded conditions increased 2.05- to 5.11-fold and 1.30- to 2.55-fold respectively as compared with upland conditions. Even though Fe plaque formation on the root surface was higher under flooded conditions than under upland conditions, it still cannot act as an effective barrier to sequester As released from flooded soils into plant tissue. The dietary risk of consuming inorganic As through water spinach planted in flooded soils was higher than in upland soils, especially in high-As-level soils. This suggests that in As-elevated soils, water spinach should be planted in upland conditions rather than in flooding conditions.

Antioxidant defense system in lettuces tissues upon various As species exposure

Characterization of antioxidant response is essential to elucidate the mechanism for plants tolerating arsenic (As) stress. Ten-day old lettuces were exposed to 50, 100, and 200 μg L-1 of arsenite (As(III)), arsenate (As(V)) or dimethylarsinic acid (DMA) for 50 days in hydroponic culture. The activities of superoxide dismutase, catalase, peroxidase, glutathione peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase, as well as the glutathione concentration in tissues, were monitored. And the speciation and occurrence of As were concurrently analyzed in roots and leaves. The results showed that As(III) was the predominant As species in lettuces upon inorganic As exposure, while DMA was the primary As species upon DMA exposure. DMA presented higher mobility than inorganic As. The reduction of As(V) in roots upon As(V) exposure and in leaves upon As(III) exposure were suggested. The alterations of enzymatic antioxidant activities and non-enzymatic antioxidant contents showed that the antioxidant responses were As species-dependent, dose-dependent and tissue-dependent. And upon As(V) and DMA exposures, antioxidant responses were more intense than that upon As(III) exposure. Further the results indicated that the antioxidant responses in lettuce were associated with the conversion and transport of As species.

Protective role of nitric oxide on nitrogen-thiol metabolism and amino acids profiling during arsenic exposure in Oryza sativa L

Nitric oxide (NO) being a signaling molecule inside the plant cells, play significant role in signaling cascades and protection against environmental stresses. However, the protective role of NO in alleviating As toxicity in rice plants is currently not available. In the present study, the level of NO, nitrogen (N), inorganic N (nitrate, ammonium), thiols {TT (Total thiols), NPT (Nonprotein thiol)} and AAs contents along with N assimilating enzymes (NR, GDH, GOGAT) were analyzed after exposure of As^III/NO treatment alone, and in combination. NO supplementation enhanced the content of N, inorganic N & thiol contents, NR, GOGAT activities, when compared with As^III exposure alone. In As^III exposed rice seedlings, content of AAs (except His, Arg, Met) reduced over the control, while supplementation of SNP improved AAs contents, compared to As^III treatment alone. In conclusion, rice seedlings supplemented with NO tolerate the As^III toxicity by reducing the N related parameters, thiol contents, altering the AA profile and enhanced the nutritional quality by increasing EAAs (essential amino acids) and NEAAs (non-essential amino acids).

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.

Ionomic responses of rice plants to the stresses of different arsenic species in hydroponics

Different ionomic profiles of plants are associated with different external stresses to which they are exposed. Investigation of ionomic variation is necessary for understanding the migration and detoxification of toxic elements in plants. In the current study, rice plants were treated with arsenite, arsenate, monomethylarsonic acid and dimethylarsinic acid in hydroponics. The ionomic responses of the rice plants to different arsenic (As) species stresses were measured and analyzed. The multielement approach is more sensitive at detecting significant variations from external environmental stresses than the consideration of several individual elements. The pairs of significant correlations between elements varied based on the rice tissues and As species used in treatment, resulting in specific correlation networks. However, some pairs of correlations existed regardless of As species treatment used in this study. Positive correlations between P and Fe were observed in rice roots treated with any of the As species, implying that P and Fe share similar biological processes. The heatmap from hierarchical cluster analysis (HCA) agreed with the principal component analysis (PCA) results in ionomic differentiation between roots and shoots. Furthermore, ionomic differences between rice plants treated with different As species were identified through PCA. This study revealed that the ionomic profiles in rice plants are sufficient to detect responses to environmental perturbations. Association studies between ionomics and genomics are necessary to further understand the potential mechanisms that promote uptake or exclusion of elements in plants.

Rapid extraction of arsenic species from traditional Chinese herbal by dual-frequency ultrasound-assisted enzymatic digestion prior to spectral analysis

Considering the huge difference of biological toxicity, it is extremely significant to recognize the exact content of arsenic species in actual samples. In this paper, a novel pretreatment technique for the efficient extraction of arsenic species from herbal samples is developed by dual-frequency ultrasound-assisted enzymatic digestion (DUED). The preservation of arsenic original form, reduction of the actual analysis time, environmental friendliness and free-interference in subsequent detection make this method over the traditional method such as wet digestion, ashing and some solvent extraction technologies. The combination of DUED and atomic fluorescence spectrometry realize the speciation analysis of arsenic in traditional Chinese medicine. The optimizations of experimental parameters have been achieved, and the potential mechanism is discussed. The experimental data showed that cellulase is suitable for the digestion of herbal matrix than α-amylase and papain. Ultrasound can significantly increase the rate of enzymatic hydrolysis of biological molecules, especially under dual-frequency ultrasound irradiation. The highest relative extraction efficiency can be obtained by combining 40 kHz ultrasonic bath (UB) with 20 kHz ultrasonic probe (UP). Two certified reference materials [CRMs, GBW(E)090066 and GBW(E)090067] and four practical herbs were used to evaluate the accuracy and practicability of the method. Inorganic arsenic, including trivalent arsenic and pentavalent arsenic, was the main species in the four herbal samples.

The speciation of inorganic arsenic in soil and vegetables irrigated with treated municipal wastewater

An efficient method using vortex-assisted microextraction based on a deep eutectic solvent followed by graphite furnace atomic absorption spectrometry was developed for the determination of arsenic species in soil and vegetables irrigated with treated wastewater.

Influence of different arsenic species on uptake, speciation and efflux of arsenic in hydroponic rice plants

Uptake, translocation and speciation of As in rice plants have been investigated through hydroponic cultivations under stress from different As species. After germination, rice seedlings were treated with arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMA) or dimethylarsinic acid (DMA) at concentrations of 50, 100, 150, 200 and 250 μg/L for 24 days. Only inorganic As species were detected in the rice plants treated with As(III) or As(V), indicating that rice seedlings could not methylate inorganic As in hydroponic culture. As(V) in the rice roots was readily reduced to As(III) after uptake; thus, As(III) was the dominant species in the rice roots (>60%) and shoots (>80%) regardless of As(III) or As(V) treatment. The increased As(III) proportion in the nutrient solutions was due to the efflux of As(III) from the rice roots. MMA with relatively low stability in the blank nutrient solution was demethylated to As(III). Moreover, demethylation and methylation of MMA might occur simultaneously in rice plants. Specific proportions of MMA and AsB were observed in the rice roots treated with DMA, implying that MMA and AsB were the DMA metabolites in rice roots after detoxification.

An improved rapid analytical method for the arsenic speciation analysis of marine environmental samples using high-performance liquid chromatography/inductively coupled plasma mass spectrometry

Arsenic contamination in marine environments is a serious issue because some arsenicals are very toxic, increasing the health risks associated with the consumption of marine products. This study describes the development of an improved rapid method for the quantification of arsenic species, including arsenite (As^III), arsenate (As^V), arsenocholine (AsC), arsenobetaine (AsB), dimethylarsinic acid (DMA), and monomethyl arsonic acid (MMA), in seaweed, sediment, and seawater samples using high-performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS). ICP-MS based on dynamic reaction cells was used to eliminate spectral interference. Ammonium nitrate- and phosphate-based eluents were used as the mobile phases for HPLC analysis, leading to shorter overall retention time (6 min) and improved peak separation. Arsenicals were extracted with a 1% HNO₃ solution that required no clean-up process and exhibited reasonable sensitivity and peak resolution. The optimized method was verified by applying it to hijiki seaweed certified reference material (CRM, NMIJ 7405-a) and to spiked blank samples of sediment and seawater. The proposed method measured the concentration of As^V in the CRM as 9.6 ± 0.6 μg/kg dry weight (dw), which is close to the certified concentration (10.1 ± 0.5 μg/kg dw). The recovery of the six arsenicals was 87-113% for the sediment and 99-101% for the seawater. In the analysis of real samples, As^V was the most abundant arsenical in hijiki and gulfweed, whereas AsB was dominant in other seaweed species. The two inorganic arsenicals (As^III and As^V) and As^V were the most dominant in the sediment and seawater samples, respectively.

Arsenic accumulation in lettuce (Lactuca sativa L.) and broad bean (Vicia faba L.) crops and its potential risk for human consumption

Exposure to arsenic (As) is considered one of the primary health risks humans face worldwide. This study was conducted to determine As absorption by broad beans and lettuce crops grown in soil with As contents and irrigated with water contaminated with this toxic element, in Pastos Chicos, Jujuy (Argentina). Total dry biomass (TDB) and total As were determined in soils, roots, leaves, pods and seeds. These data were used to determine several parameters, such as translocation (TF) and bioconcentration (BCF) factors, target hazard quotient (THQ), and carcinogenic risk (CR). Broad bean plants had the lowest biomass production when exposed to As in irrigation water and soil. Lettuce plants presented TDB reductions of 33.3 and 42.8% when grown in soil polluted with As, and in control soil under irrigation with contaminated water, respectively. The presence of this toxicant in broad bean seeds and lettuce leaves (edible parts) exceeded the limits established by Código Alimentario Argentino, i.e. 0.10 and 0.30 mg/kg, respectively. THQ values for lettuce leaves were higher than 1, the same as those for broad bean seeds when grown in soil with As contents and irrigated with arsenic-contaminated water, thus suggesting that consumers would run significant risks when consuming these vegetables. Furthermore, this type of exposure to As implied a CR that exceeded the acceptable 1 × 10^-4 risk level. Hence, we may conclude that consuming lettuce and broad beans grown at the evaluated site brings about considerable health risks for local residents.

Occurrence, toxicity, and speciation analysis of arsenic in edible mushrooms

Owing to the strong concentration and biotransformation of arsenic, the influence of some edible mushrooms on human health has attracted widespread attention. The toxicity of arsenic greatly depends on its species, so the speciation analysis of arsenic is of critical importance. The aim of the present review is to highlight recent advances in arsenic speciation analysis in edible mushrooms. We summarized the contents and distribution of arsenic species in some edible mushrooms, the methods of sample preparation, and the techniques for their identification and quantification. Stability of the arsenic species during sample pretreatment and storage is also briefly discussed.

The role of submerged macrophytes in phytoremediation of arsenic from contaminated water: A case study on Vallisneria natans (Lour.) Hara

Arsenic contamination of water is a global concern due to its heavy threat to human health. In this study, the submerged macrophyte Vallisneria natans (Lour.) Hara was used to remove environmentally relevant concentrations of arsenic in the binary As(III)/As(V) system. The concentrations of total arsenic (tAs) and As(III) in water dropped rapidly within 3 days, while As(V) first increased slightly within 3 days and then gradually decreased. About 1.2% dimethylarsinate (DMA) was detected at the 14th day of treatment. These findings indicated that As(III) could be oxidized to As(V) and methylated to DMA in water with V. natans. In relation to V. natans, both tAs and As(V) were much higher in roots compared to leaves. Arsenate was the predominant species (≥ 95.65 ± 0.10%) in roots, and As(III) was only found at the 14th day (3.45-6.96 mg kg^-1). In leaves, As(III) significantly increased (P < 0.05) as the treatment duration increased. The proportions of As(V) (27.99-40.03%) were lower than those of As(III) and arsenobetaine (AsB) was detected (0.52-1.87 mg kg^-1) after 7 d. The results of arsenic speciation demonstrated that the transformation of arsenic species in V. natans included As(V) reduction and As(III) methylation to AsB. There were a decrease in chlorophyll content, and an increase in MDA level and antioxidant enzymes (SOD, CAT, and POD) activities. The MDA level was much higher in leaves than roots, whereas the activities of SOD, CAT, and POD were the opposite, suggesting their possible role in arsenic resistance and detoxification. Our results indicate the potential of V. natans in phytoremediation of arsenic-contaminated water.

Dietary intake and urinary metals among pregnant women in the Pacific Northwest

Pregnancy is a period when the mother and her offspring are susceptible to the toxic effects of metals. We investigated associations of intake of frequently consumed foods with urinary metals concentrations among pregnant women in the Pacific Northwest. We measured urinary cadmium (U-Cd), arsenic (U-As) and molybdenum (U-Mo) concentrations from spot urine samples in early pregnancy (15 weeks of gestation, on average) among 558 women from Seattle and Tacoma, Washington. We assessed periconceptional dietary intake using a semi-quantitative food frequency questionnaire (FFQ). We also determined early pregnancy zinc concentrations in serum. Statistical analyses involved multivariable linear regression models, adjusted for smoking status, age, race/ethnicity, multivitamin and supplement use, education, estimated total energy intake, and gravidity. The geometric mean and range in μg/g creatinine for U-Cd, U-As and U-Mo were 0.29 (0.1-8.2), 18.95 (3-550), and 72.1 (15-467), respectively. U-Cd was positively associated with dietary zinc intake (P-value = 0.004) and serum zinc (P-value<0.001) while it was negatively associated with coffee intake (P-value = 0.03). U-As was positively associated with dietary fish [(Lean fish, fatty fish, shellfish and non-fried fish) (P-values<0.01)], selenium (P-value = 0.004), zinc (P-value = 0.017), vegetables (P-value = 0.004), and low-fat yogurt (P-value = 0.03). Women who reported higher intake of dietary magnesium (Mg)(P-value = 0.04), insoluble fiber (P-value = 0.03), and low-fat yogurt (P-value = 0.04) had higher U-Mo concentrations. Our study suggests that vegetables, fish, fiber and yogurt might be significant dietary sources of metals. Future studies aimed at investigating the risk of exposure to metals from other various food sources among reproductive-age and pregnant women are needed.

Determination of Arsenic Species in Ophiocordyceps sinensis from Major Habitats in China by HPLC-ICP-MS and the Edible Hazard Assessment

This study sought to determine the concentration and distribution of arsenic (As) species in Ophiocordyceps sinensis (O. sinensis), and to assess its edible hazard for long term consumption. The total arsenic concentrations, measured through inductively coupled plasma mass spectrometry (ICP-MS), ranged from 4.00 mg/kg to 5.25 mg/kg. As determined by HPLC-ICP-MS, the most concerning arsenic species—AsB, MMA^V, DMA^V, As^V, and As^Ш—were either not detected (MMA^V and DMA^V) or were detected as minor As species (AsB: 1.4⁻2.9%; As^V: 1.3⁻3.2%, and As^Ш: 4.1⁻6.0%). The major components were a cluster of unknown organic As (uAs) compounds with As^Ш, which accounted for 91.7⁻94.0% of the As content. Based on the H₂O₂ test and the chromatography behavior, it can be inferred that, the uAs might not be toxic organic As. Estimated daily intake (EDI), hazard quotient (HQ), and cancer risk (CR) caused by the total As content; the sum of inorganic As (iAs) and uAs, namely i+uAs; and iAs exposure from long term O. sinensis consumption were calculated and evaluated through equations from the US Environmental Protection Agency and the uncertainties were analyzed by Monte-Carlo Simulation (MCS). EDI_{total As} and EDI_i+uAs are approximately ten times more than EDI_iAs; HQ_totalAs and HQ_i+uAs > 1 while HQ_iAs < 1; and CR_{total As} and CR_i+uAs > 1 × 10⁻⁴ while CR_iAs < 1 × 10⁻⁴. Thus, if the uAs is non-toxic, there is no particular risk to local consumers and the carcinogenic risk is acceptable for consumption of O. sinensis because the concentration of toxic iAs is very low.

Speciation analysis of six arsenic species in marketed shellfish: Extraction optimization and health risk assessment

A comparative study between microwave assisted and sonication methods was carried out to extract arsenic (As) species in shellfish samples using different extractants. Six As species including arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB) and arsenocholine (AsC) were simultaneously separated and determined by the HPLC-ICP-MS method. The microwave assisted method exhibited higher efficiency than sonication, especially using diluted HNO₃ as extractant. By compromising extraction efficiency, pretreatment time and stability of As species, the microwave assisted method using 1% HNO₃ at 100°C for 1.5h was selected to extract As from real samples. The proposed method has been applied to extract and determine As species in shellfish samples. The result of correlation analysis indicated that the proportion of AsB in the shellfish samples was decreased with total As concentration increasing due to the biotransformation threshold from inorganic As to AsB.

Accumulation, translocation and conversion of six arsenic species in rice plants grown near a mine impacted city

Paddy rice (Oryza sativa L.) as the staple food in China was found to be efficient in accumulating arsenic (As) due to cultivated in flooded paddy soil. Uptake and translocation of As in rice plant depended on the As species. In this work, rice plant samples including roots, straws and grains as well as rhizosphere soils were collected from paddy fields near Changsha, a mine impacted city in Southern China. The total As concentrations in the collected samples were observed in the descending order as root > soil > straw > grain. The predominant As species detected in rice plants were inorganic forms: arsenite [As(III)] and arsenate [As(V)]. Except monomethylarsonate (MMA) and dimethylarsinate (DMA), other two organoarsenicals, arsenobetaine (AsB) and arsenocholine (AsC), were also detected in rice plants. DMA and AsB were mainly formed in rice roots with the assistance of microorganisms. MMA and AsC detected in straws might be derived from methylation and oxidation of As(III). The results of multiple linear regressions indicated that the straw As species were remarkable predictors of the corresponding grain As species. Demethylation or degradation of MMA, DMA and AsC were predicted when translocated from straw to grain.

Arsenic accumulation and physiological attributes of spinach in the presence of amendments: an implication to reduce health risk

The current study examined the effect of calcium (Ca) and ethylenediaminetetraacetic acid (EDTA) on arsenic (As) uptake and toxicity to spinach (Spinacia oleracea) as well as assessed the potential human health risks. Spinach seedlings were exposed to three levels of As (25, 125, and 250 μM) alone or together with three levels of EDTA (25, 125, and 250 μM) and Ca (1, 5, and 10 mM). The effect of EDTA and Ca was assessed in terms of As contents in roots and shoots, hydrogen peroxide production, chlorophyll contents, and lipid peroxidation. The accumulation and toxicity of As to spinach plants increased with increasing As levels in nutrient solution. Exposure to As resulted in lipid peroxidation and reduced chlorophyll contents. The highest level of As alone (250 μM) showed highest human health risk (hazard quotient of 7.09 at As-250). Addition of EDTA enhanced As accumulation by spinach, while reduced As toxicity to spinach, as well as human health risk (hazard quotient of 4.01 at As-250). Similarly, Ca significantly reduced As toxicity to spinach and the human health risks (hazard quotient of 3.79 at As-250) by reducing its accumulation in spinach. Higher levels of Ca were more effective in reducing As uptake and toxicity as well as enhancing chlorophyll contents.