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Trace element concentrations in toenail clippings have increasingly been used to measure trace element exposure in epidemeological research. Conventional methods such as inductively coupled plasma mass spectrometry (ICP-MS) and high-performance liquid chromatography ICP-MS (HPLC-ICP-MS) are commonly used to measure trace elements and their speciation in toenails. However, the impact of the removal of external contamination on trace element quantification has not been thoroughly studied. In this work, the microdistribution of trace elements (As, Ca, Co, Cu, Fe, K, Mn, Ni, Rb, S, Sr, Ti, and Zn) in dirty and washed toenails and the speciation of As in situ in toenails were investigated using synchrotron X-ray fluorescence microscopy (XFM) and laterally resolved X-ray absorption near edge spectroscopy (XANES). XFM showed different distribution patterns for each trace element, consistent with their binding properties and nail structure. External (terrestrial) contamination was identified and distinguished from the endogenous accumulation of trace elements in toenails─contaminated areas were characterized by the co-occurrence of Co, Fe, and Mn with elements such as Ti and Rb (i.e., indicators of terrestrial contamination). The XANES spectra showed the presence of one As species in washed toenails, corresponding to As bound to sulfhydryl groups. In dirty specimens, a mixed speciation was found in localized areas, containing As III -S species and As V species. Arsenic V is thought to be associated with surface contamination and exogenous As. These findings provide new insights into the speciation of arsenic in toenails, the microdistribution of trace elements, and the effectiveness of a cleaning protocol in removing external contamination.

The inductively coupled plasma mass spectrometry (ICPMS) has been attracting increasing attention for many applications as an element-selective chromatographic detector. A major and fundamental limitation in coupling ICPMS with liquid chromatography is the limited compatibility with organic solvents, which has so far been addressed via a tedious approach, collectively referred to as the "organic ICPMS mode", that can decrease detection sensitivity by up to 100-fold. Herein, we report 1,2-hexanediol as a new eluent in high-performance liquid chromatography-ICPMS which enables avoiding the current limitations. Unlike commonly used eluents, 1,2-hexanediol was remarkably compatible with ICPMS detection at high flow rates of 1.5 mL min -1 and concentrations of at least 30% v/v, respectively, under the standard conditions and instrumental setup normally used with 100% aqueous media. Sensitivity for all tested elements (P, S, Cl, Br, Se, and As) was enhanced with 10% v/v 1,2-hexanediol relative to that of 100% aqueous media by 1.5-7-fold depending on the element. Concentrations of 1,2-hexanediol at ≤30% v/v were superior in elution strength to concentrations at >90% v/v of the common organic phases, which greatly decreases the amount of carbon required to elute highly hydrophobic compounds such as lipids and steroids, enabling detection at ultra-trace levels. The proposed approach was applied to detect arsenic-containing fatty acids in spiked human urine, and detection limits of <0.01 μg As L -1 were achieved, which is >100-fold lower than those previously reported using the organic ICPMS mode. Nontargeted speciation analysis in Allium sativum revealed the presence of a large number of hydrophobic sulfur-containing metabolomic features at trace levels.

Background: Shrimp is a worldwide food commodity, it is a source of several nutrients and vitamins; however, this food is one of the major sources of arsenic for humans. Legislation around the world set limits for the concentration of this element in crustaceans but is mainly concerned with total analysis. Although, arsenic species have different toxicities and total analysis could be ineffective for making decisions about food security., Methods: Samples of wild (Farfantepenaeus brasiliensis) and farmed shrimps (Litopenaeus vannamei) from NE Brazil were fractionated in subsamples of carapace, muscle tissue and viscera. The whole shrimp as well as the animal tissue fractions were decomposed using microwave digestion and total arsenic was analyzed by mass spectrometry inductively coupled plasm (ICP-MS). The water-soluble arsenic species were extracted, and the extract was carried for speciation analysis using HPLC-ICP-MS with an anionic and cationic column., Results: Total As in wild shrimp samples exceeded Brazilian and USA food legislation by one order of magnitude, with concentrations of 11.5 ± 0.5 mg kg -1 , while farmed shrimp had significantly lower total arsenic levels (0.53 ± 0.09 mg kg -1 ). More than 60% of the As was in the edible fraction in the wild shrimp, while in farmed shrimp this was less than 50%. The speciation analysis showed that arsenobetaine (AsB) was the predominant As form and iAs was below the Chinese legislation levels (iAs <0.50 mg kg -1 ) for shrimp in both species., Conclusion: The arsenic uptake in wild and farmed shrimp was discussed and some differences were found related to feed and salinity. About legislation, it has been concluded that most food legislations that consider only tAs are not appropriate to assess the toxicity of As in seafood. It is necessary to update the legislation of food control agencies to insert As speciation analysis in their protocols., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

Impact of zero valent iron (Fe°) amendment on grain-yield (GY) and grain-As and Cd accumulation in rice (Oryza sativa L.) cultivars Kilombero and Faya were investigated. Rice plants were amended with Fe° dosages of 0, 3.1, 6.2, and 12.4 g Fe°/kg soil in pots in greenhouse experiments under continuous flooding water regime. GY in each treatment was determined at maturity, grain-As and Cd and arsenic species concentrations were determined using ICP-MS and HPLC tandem ICP-MS respectively. Mean GY in Faya (5.5 ± 1.0 g/plant) and Kilombero (4.2 ± 0.4 g/plant) amended with at least 6.2 g Fe°/kg soil were at least 57% and 22% respectively significantly higher (F = 11; p = 0.003) than that in controls (3.7 ± 0.6 and 3.4 ± 0.4 g/plant). For As bioaccumulation, mean grain-As concentration in Faya T2 (≤227 ± 32 μg/kg) and Kilombero (≤218 ± 25 μg/kg) amended with at least 6.2 g Fe°/kg soil in were at least 83% and 77% respectively significantly lower (F = 7; p = 0.004) than that in controls (973 ± 43 μg/kg and 1278 ± 208 μg/kg). Mean grain-Cd concentrations in Faya (10 ± 2 μg/kg) and Kilombero (13 ± 3 μg/kg) amended with corresponding Fe° dosages were at least 26% and 39% significantly lower (F = 4; p < 0.05) than that in controls (18 ± 3 and 23 ± 1 μg/kg). Results indicated that amending Kilombero with at least 6.2 g/kg Fe° effectively optimally regulated both grain-As and Cd accumulation to values lower than the European Commission's legislated maximum contaminant limits (MCL) of 200 μg/kg without negating grain yield benefits. Our results suggest that bioaccumulation of both As and Cd in rice grains may be completely circumvented by adopting cultivar-specific Fe° amendment dosage., Competing Interests: Declaration of competing interest The authors have no conflict of interests to declare., (Crown Copyright © 2021. Published by Elsevier B.V. All rights reserved.)

With recently legislated maximum levels of inorganic arsenic (iAs) in white and brown rice in Canada, the regulatory bodies are evaluating the need for regulation of As levels in infant food products. Rice is a major part of infants' diet, and therefore, the presence of As in this staple food causes concerns. So far, the scientific community was lacking suitable certified reference material (CRM) which could be used to assess the accuracy of developed analytical methods for As speciation in infants' food products. As a result, we have developed BARI-1, a baby cereal coarse rice flour reference material which was certified for total arsenic (0.248 ± 0.018 mg kg -1 ), cadmium (0.0134 ± 0.0014 mg kg -1 ), mercury (0.0026 ± 0.0003 mg kg -1 ), lead (0.0064 ± 0.0016 mg kg -1 ), inorganic As (0.113 ± 0.016 mg kg -1 ) and dimethylarsinic acid (DMA) (0.115 ± 0.010 mg kg -1 ), and reference value for monomethylarsonic acid (MMA) (0.0045 ± 0.0008 mg kg -1 ) was reported. We also observed trace amounts of an unknown As compound, with chromatographic retention time close to DMA. Participating laboratories were allowed to use their in-house-validated extraction and/or digestion methods, and the detection of total metals was done by ICP-MS whereas HPLC-ICP-MS was used for As speciation. Despite the diversity in sample preparation and quantitation methods, reported values were in good agreement. For iAs measurement, the comparison between hydride generation ICP-MS and HPLC-ICP-MS found iAs overestimation with the former method, possibly due to interference from DMA. The certification was accomplished with a CRM rapid response approach in collaborative, focused effort completing the CRM development in few months instead of the typical multiyear project. This approach allowed to respond to measurement needs in a timely fashion. Graphical abstract.

Brazil is a major producer of rice, but there is not enough information about As and Cd in rice grown under different conditions in this country. Here, As and Cd were determined by ICP-MS and species of As by HPLC-ICP-MS in Brazilian husked rice, covering diverse cultivars and regions, as well as upland and flooded production systems. Significant differences were observed for contents of both elements according to the origin of rice. All samples were below the maximum limit for Cd (400 µg/kg) set by national legislation, while nine samples presented total As above the legislation limit (300 µg/kg). From 24 samples analyzed for As species, 42% showed iAs above the European limit for production of food to infants (100 µg/kg). The total As content in samples from Mato Grosso state presented a maximum value of 6 µg/kg, which combined with low Cd content make interesting further studies., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A commercial arsenic field kit designed to measure inorganic arsenic (iAs) in water was modified into a field deployable method (FDM) to measure iAs in rice. While the method has been validated to give precise and accurate results in the laboratory, its on-site field performance has not been evaluated. This study was designed to test the method on-site in Malawi in order to evaluate its accuracy and precision in determination of iAs on-site by comparing with a validated reference method and giving original data on inorganic arsenic in Malawian rice and rice-based products. The method was validated by using the established laboratory-based HPLC-ICPMS. Statistical tests indicated there were no significant differences between on-site and laboratory iAs measurements determined using the FDM (p = 0.263, ά = 0.05) and between on-site measurements and measurements determined using HPLC-ICP-MS (p = 0.299, ά = 0.05). This method allows quick (within 1 h) and efficient screening of rice containing iAs concentrations on-site., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: In the late twentieth century, emergence of high rates of treatment failure with antimonial compounds (SSG) for visceral leishmaniasis (VL) caused a public health crisis in Bihar, India. We hypothesize that exposure to arsenic through drinking contaminated groundwater may be associated with SSG treatment failure due to the development of antimony-resistant parasites., Methods: A retrospective cohort design was employed, as antimony treatment is no longer in routine use. The study was performed on patients treated with SSG between 2006 and 2010. Outcomes of treatment were assessed through a field questionnaire and treatment failure used as a proxy for parasite resistance. Arsenic exposure was quantified through analysis of 5 water samples from within and surrounding the patient's home. A logistic regression model was used to evaluate the association between arsenic exposure and treatment failure. In a secondary analysis survival curves and Cox regression models were applied to assess the risk of mortality in VL patients exposed to arsenic., Results: One hundred and ten VL patients treated with SSG were analysed. The failure rate with SSG was 59%. Patients with high mean local arsenic level had a non-statistically significant higher risk of treatment failure (OR = 1.78, 95% CI: 0.7-4.6, p = 0.23) than patients using wells with arsenic concentration <10 μg/L. Twenty one patients died in our cohort, 16 directly as a result of VL. Arsenic levels ≥ 10 μg/L increased the risk of all-cause (HR 3.27; 95% CI: 1.4-8.1) and VL related (HR 2.65; 95% CI: 0.96-7.65) deaths. This was time dependent: 3 months post VL symptom development, elevated risks of all-cause mortality (HR 8.56; 95% CI: 2.5-29.1) and of VL related mortality (HR 9.27; 95% CI: 1.8-49.0) were detected., Discussion/conclusion: This study indicates a trend towards increased treatment failure in arsenic exposed patients. The limitations of the retrospective study design may have masked a strong association between arsenic exposure and selection for antimonial resistance in the field. The unanticipated strong correlation between arsenic exposure and VL mortality warrants further investigation.

The Indian subcontinent is the only region where arsenic contamination of drinking water coexists with widespread resistance to antimonial drugs that are used to treat the parasitic disease visceral leishmaniasis. We have previously proposed that selection for parasite resistance within visceral leishmaniasis patients who have been exposed to trivalent arsenic results in cross-resistance to the related metalloid antimony, present in the pentavalent state as a complex in drugs such as sodium stibogluconate (Pentostam) and meglumine antimonate (Glucantime). To test this hypothesis, Leishmania donovani was serially passaged in mice exposed to arsenic in drinking water at environmentally relevant levels (10 or 100 ppm). Arsenic accumulation in organs and other tissues was proportional to the level of exposure and similar to that previously reported in human liver biopsies. After five monthly passages in mice exposed to arsenic, isolated parasites were found to be completely refractory to 500 μg · mL(-1) Pentostam compared with the control passage group (38.5 μg · mL(-1)) cultured in vitro in mouse peritoneal macrophages. Reassessment of resistant parasites following further passage for 4 mo in mice without arsenic exposure showed that resistance was stable. Treatment of infected mice with Pentostam confirmed that resistance observed in vitro also occurred in vivo. We conclude that arsenic contamination may have played a significant role in the development of Leishmania antimonial resistance in Bihar because inadequate treatment with antimonial drugs is not exclusive to India, whereas widespread antimonial resistance is.

A field and market basket study (~1300 samples) of locally grown fruits and vegetables from historically mined regions of southwest (SW) England (Cornwall and Devon), and as reference, a market basket study of similarly locally grown produce from the northeast (NE) of Scotland (Aberdeenshire) was conducted to determine the concentration of total and inorganic arsenic present in produce from these two geogenically different areas of the U.K. On average 98.5% of the total arsenic found was present in the inorganic form. For both the market basket and the field survey, the highest total arsenic was present in open leaf structure produce (i.e., kale, chard, lettuce, greens, and spinach) being most likely to soil/dust contamination of the open leaf structure. The concentration of total arsenic in potatoes, swedes, and carrots was lower in peeled produce compared to unpeeled produce. For baked potatoes, the concentration of total arsenic in the skin was higher compared to the total arsenic concentration of the potato flesh, this difference in localization being confirmed by laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS). For all above ground produce (e.g., apples), peeling did not have a significant effect on the concentration of total arsenic present.

Determination of the speciation of arsenic in groundwaters, using cathodic stripping voltammetry (CSV), is severely hampered by high levels of iron and manganese. Experiments showed that the interference is eliminated by addition of EDTA, making it possible to determine the arsenic speciation on-site by CSV. This work presents the CSV method to determine As(III) in high-iron or -manganese groundwaters in the field with only minor sample treatment. The method was field-tested in West-Bengal (India) on a series of groundwater samples. Total arsenic was subsequently determined after acidification to pH 1 by anodic stripping voltammetry (ASV). Comparative measurements by ICP-MS as reference method for total As, and by HPLC for its speciation, were used to corroborate the field data in stored samples. Most of the arsenic (78±0.02%) was found to occur as inorganic As(III) in the freshly collected waters, in accordance with previous studies. The data shows that the modified on-site CSV method for As(III) is a good measure of water contamination with As. The EDTA was also found to be effective in stabilising the arsenic speciation for longterm sample storage at room temperature. Without sample preservation, in water exposed to air and sunlight, the As(III) was found to become oxidised to As(V), and Fe(II) oxidised to Fe(III), removing the As(V) by adsorption on precipitating Fe(III)-hydroxides within a few hours., (Copyright © 2011 Elsevier B.V. All rights reserved.)

It has previously been shown that across different arsenic (As) soil environments, a decrease in grain selenium (Se), zinc (Zn), and nickel (Ni) concentrations is associated with an increase in grain As. In this study we aim to determine if there is a genetic element for this observation or if it is driven by the soil As environment. To determine the genetic and environmental effect on grain element composition, multielement analysis using ICP-MS was performed on rice grain from a range of rice cultivars grown in 4 different field sites (2 in Bangladesh and 2 in West Bengal). At all four sites a negative correlation was observed between grain As and grain Ni, while at three of the four sites a negative correlation was observed between grain As and grain Se and grain copper (Cu). For manganese, Ni, Cu, and Se there was also a significant genetic interaction with grain arsenic indicating some cultivars are more strongly affected by arsenic than others.

Arsenic (As) accumulation in rice grains is a risk to human health. The mechanism of transfer of As from the shoot into the grain during grain filling is unknown at present. In this study As speciation in the shoot and grains at maturity were examined, and the relationships between phosphorus (P) and As, and silicon (Si) and As were established in a wide range of cultivars grown in As contaminated field trials in Bangladesh and China. No correlations were observed between shoot and grain speciation, with the inorganic form comprising 93.0-97.0% of As in the shoot and 63.0-83.7% in the grains. The percentage of dimethylarsinic acid (DMA) was between 1.4 and 6.6% in the shoot and 14.6 and 37.0% in the grains; however, the concentrations were comparable, ranging from 0.07 to 0.26 mg kg(-1) in the shoots and 0.03 to 0.25 mg kg(-1) in the grains. A positive correlation was observed between shoot As and shoot Si, however, no correlation was observed between shoot Si and grain As. A significant negative correlation was observed between shoot P and grain As concentrations. These results suggest that the translocation of As into the grain from the shoots is potentially using P rather than Si transport mechanisms. The findings also indicate that inorganic As and DMA translocation to the grain differ considerably.

Rice (Oryza sativa) is the staple food for over half the world's population yet may represent a significant dietary source of inorganic arsenic (As), a nonthreshold, class 1 human carcinogen. Rice grain As is dominated by the inorganic species, and the organic species dimethylarsinic acid (DMA). To investigate how As species are unloaded into grain rice, panicles were excised during grain filling and hydroponically pulsed with arsenite, arsenate, glutathione-complexed As, or DMA. Total As concentrations in flag leaf, grain, and husk, were quantified by inductively coupled plasma mass spectroscopy and As speciation in the fresh grain was determined by x-ray absorption near-edge spectroscopy. The roles of phloem and xylem transport were investigated by applying a +/- stem-girdling treatment to a second set of panicles, limiting phloem transport to the grain in panicles pulsed with arsenite or DMA. The results demonstrate that DMA is translocated to the rice grain with over an order magnitude greater efficiency than inorganic species and is more mobile than arsenite in both the phloem and the xylem. Phloem transport accounted for 90% of arsenite, and 55% of DMA, transport to the grain. Synchrotron x-ray fluorescence mapping and fluorescence microtomography revealed marked differences in the pattern of As unloading into the grain between DMA and arsenite-challenged grain. Arsenite was retained in the ovular vascular trace and DMA dispersed throughout the external grain parts and into the endosperm. This study also demonstrates that DMA speciation is altered in planta, potentially through complexation with thiols.

The concentration of arsenic (As) in rice grains has been identified as a risk to human health. The high proportion of inorganic species of As (As(i)) is of particular concern as it is a nonthreshold, class 1 human carcinogen. To be able to breed rice with low grain As, an understanding of genetic variation and the effect of different environments on genetic variation is needed. In this study, 13 cultivars grown at two field sites each in Bangladesh, India, and China are evaluated for grain As. There was a significant site, genotype, and site by genotype interaction for total grain As. Correlations were observed only between sites in Bangladesh and India, not between countries or within the Chinese sites. For seven cultivars the As was speciated which revealed significant effects of site, genotype, and site by genotype interaction for percentage As(i). Breeding low grain As cultivars that will have consistently low grain As and low As(i), over multiple environments using traditional breeding approaches may be difficult, although CT9993-5-10-1-M, Lemont, Azucena, and Te-qing in general had low grain As across the field sites.

For the world's population, rice consumption is a major source of inorganic arsenic (As), a nonthreshold class 1 carcinogen. Reducing the amount of total and inorganic As within the rice grain would reduce the exposure risk. In this study, grain As was measured in 76 cultivars consisting of Bangladeshi landraces, improved Bangladesh Rice Research Institute (BRRI) cultivars, and parents of permanent mapping populations grown in two field sites in Bangladesh, Faridpur and Sonargaon, irrigated with As-contaminated tubewell water. Grain As ranged from 0.16 to 0.74 mg kg(-1) at Faridpur and from 0.07 to 0.28 mg kg(-1) at Sonargaon. Highly significant cultivar differences were detected and a significant correlation (r = 0.802) in the grain As between the two field sites was observed, indicating stable genetic differences in As accumulation. The cultivars with the highest concentration of grain As were the Bangladeshi landraces. Landraces with red bran had significantly more grain As than the cultivars with brown bran. The percent of inorganic As decreased linearly with increasing total As, but genetic variation within this trend was identified. A number of local cultivars with low grain As were identified. Some tropical japonica cultivars with low grain As have the potential to be used in breeding programs and genetic studies aiming to identify genes which decrease grain As.

Rice has been demonstrated to be one of the major contributors to arsenic (As) in human diets in addition to drinking water, but little is known about rice products as an additional source of As exposure. Rice products were analyzed for total As and a subset of samples were measured for arsenic speciation using high performance liquid chromatography interfaced with inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). A wide range of rice products had total and inorganic arsenic levels that typified those found in rice grain including, crisped rice, puffed rice, rice crackers, rice noodles and a range of Japanese rice condiments as well as rice products targeted at the macrobiotic, vegan, lactose intolerant and gluten intolerance food market. Most As in rice products are inorganic As (75.2-90.1%). This study provides a wider appreciation of how inorganic arsenic derived from rice products enters the human diet.

An extensive data set of total arsenic analysis for 901 polished (white) grain samples, originating from 10 countries from 4 continents, was compiled. The samples represented the baseline (i.e., notspecifically collected from arsenic contaminated areas), and all were for market sale in major conurbations. Median total arsenic contents of rice varied 7-fold, with Egypt (0.04 mg/kg) and India (0.07 mg/kg) having the lowest arsenic content while the U.S. (0.25 mg/kg) and France (0.28 mg/kg) had the highest content. Global distribution of total arsenic in rice was modeled by weighting each country's arsenic distribution by that country's contribution to global production. A subset of 63 samples from Bangladesh, China, India, Italy, and the U.S. was analyzed for arsenic species. The relationship between inorganic arsenic contentversus total arsenic contentsignificantly differed among countries, with Bangladesh and India having the steepest slope in linear regression, and the U.S. having the shallowest slope. Using country-specific rice consumption data, daily intake of inorganic arsenic was estimated and the associated internal cancer risk was calculated using the U.S. Environmental Protection Agency (EPA) cancer slope. Median excess internal cancer risks posed by inorganic arsenic ranged 30-fold for the 5 countries examined, being 0.7 per 10,000 for Italians to 22 per 10,000 for Bangladeshis, when a 60 kg person was considered.

Total arsenic and arsenic speciation was performed on different rice types (basmati, long-grain, polished ([white] and wholegrain [brown]) that had undergone various forms of cooking. The effect of rinse washing, low volume (2.5 : 1 water : rice) and high volume (6 : 1 water : rice) cooking, as well as steaming, were investigated. Rinse washing was effective at removing circa. 10% of the total and inorganic arsenic from basmati rice, but was less effective for other rice types. While steaming reduced total and inorganic arsenic rice content, it did not do so consistently across all rice types investigated. Low volume water cooking did not remove arsenic. High volume water : rice cooking did effectively remove both total and inorganic arsenic for the long-grain and basmati rice (parboiled was not investigated in high volume cooking water experiment), by 35% and 45% for total and inorganic arsenic content, respectively, compared to uncooked (raw) rice. To reduce arsenic content of cooked rice, specifically the inorganic component, rinse washing and high volume of cooking water are effective.

Isatis capadocica, a brassica collected from Iranian arsenic-contaminated mine spoils and control populations, was examined to determine arsenate tolerance, metabolism and accumulation. I. cappadocica exhibited arsenate hypertolerance in both mine and nonmine populations, actively growing at concentrations of > 1 mm arsenate in hydroponic solution. I. cappadocica had an ability to accumulate high concentrations of arsenic in its shoots, in excess of 100 mg kg(-1) DW, with a shoot : root transfer ratio of > 1. The ability to accumulate arsenic was exhibited in both hydroponics and contaminated soils. Tolerance in this species was not achieved through suppression of high-affinity phosphate/arsenate root transport, in contrast to other monocotyledons and dicotyledons. A high percentage (> 50%) of arsenic in the tissues was phytochelatin complexed; however, it is argued that this is a constitutive, rather than an adaptive, mechanism of tolerance.

Rice is more elevated in arsenic than all other grain crops tested to date, with whole grain (brown) rice having higher arsenic levels than polished (white). It is reported here that rice bran, both commercially purchased and specifically milled for this study, have levels of inorganic arsenic, a nonthreshold, class 1 carcinogen, reaching concentrations of approximately 1 mg/kg dry weight, around 10-20 fold higher than concentrations found in bulk grain. Although pure rice bran is used as a health food supplement, perhaps of more concern is rice bran solubles, which are marketed as a superfood and as a supplement to malnourished children in international aid programs. Five rice bran solubles products were tested, sourced from the United States and Japan, and were found to have 0.61-1.9 mg/kg inorganic arsenic. Manufactures recommend approximately 20 g servings of the rice bran solubles per day, which equates to a 0.012-0.038 mg intake of inorganic arsenic. There are no maximum concentration levels (MCLs) set for arsenic or its species in food stuffs. EU and U.S. water regulations, set at 0.01 mg/L total or inorganic arsenic, respectively, are based on the assumption that 1 L of water per day is consumed, i.e., 0.01 mg of arsenic/ day. At the manufacturers recommended rice bran solubles consumption rate, inorganic arsenic intake exceeds 0.01 mg/ day, remembering that rice bran solubles are targeted at malnourished children and that actual risk is based on mg kg(-1) day(-1) intake.

Inorganic arsenic is a chronic exposure carcinogen. Analysis of UK baby rice revealed a median inorganic arsenic content (n=17) of 0.11 mg/kg. By plotting inorganic arsenic against total arsenic, it was found that inorganic concentrations increased linearly up to 0.25 mg/kg total arsenic, then plateaued at 0.16 mg/kg at higher total arsenic concentrations. Inorganic arsenic intake by babies (4-12 months) was considered with respect to current dietary ingestion regulations. It was found that 35% of the baby rice samples analysed would be illegal for sale in China which has regulatory limit of 0.15 mg/kg inorganic arsenic. EU and US food regulations on arsenic are non-existent. When baby inorganic arsenic intake from rice was considered, median consumption (expressed as microg/kg/d) was higher than drinking water maximum exposures predicted for adults in these regions when water intake was expressed on a bodyweight basis.

Synchrotron-based X-ray fluorescence (S-XRF) was utilized to locate arsenic (As) in polished (white) and unpolished (brown) rice grains from the United States, China, and Bangladesh. In white rice As was generally dispersed throughout the grain, the bulk of which constitutes the endosperm. In brown rice As was found to be preferentially localized at the surface, in the region corresponding to the pericarp and aleurone layer. Copper, iron, manganese, and zinc localization followed that of arsenic in brown rice, while the location for cadmium and nickel was distinctly different, showing relatively even distribution throughout the endosperm. The localization of As in the outer grain of brown rice was confirmed by laser ablation ICP-MS. Arsenic speciation of all grains using spatially resolved X-ray absorption near edge structure (micro-XANES) and bulk extraction followed by anion exchange HPLC-ICP-MS revealed the presence of mainly inorganic As and dimethylarsinic acid (DMA). However, the two techniques indicated different proportions of inorganic:organic As species. A wider survey of whole grain speciation of white (n=39) and brown (n=45) rice samples from numerous sources (field collected, supermarket survey, and pot trials) showed that brown rice had a higher proportion of inorganic arsenic present than white rice. Furthermore, the percentage of DMA present in the grain increased along with total grain arsenic.

The mechanisms of arsenic (As) hyperaccumulation in Pteris vittata, the first identified As hyperaccumulator, are unknown. We investigated the interactions of arsenate and phosphate on the uptake and distribution of As and phosphorus (P), and As speciation in P. vittata. In an 18-d hydroponic experiment with varying concentrations of arsenate and phosphate, P. vittata accumulated As in the fronds up to 27,000 mg As kg(-1) dry weight, and the frond As to root As concentration ratio varied between 1.3 and 6.7. Increasing phosphate supply decreased As uptake markedly, with the effect being greater on root As concentration than on shoot As concentration. Increasing arsenate supply decreased the P concentration in the roots, but not in the fronds. Presence of phosphate in the uptake solution decreased arsenate influx markedly, whereas P starvation for 8 d increased the maximum net influx by 2.5-fold. The rate of arsenite uptake was 10% of that for arsenate in the absence of phosphate. Neither P starvation nor the presence of phosphate affected arsenite uptake. Within 8 h, 50% to 78% of the As taken up was distributed to the fronds, with a higher translocation efficiency for arsenite than for arsenate. In fronds, 49% to 94% of the As was extracted with a phosphate buffer (pH 5.6). Speciation analysis using high-performance liquid chromatography-inductively coupled plasma mass spectroscopy showed that >85% of the extracted As was in the form of arsenite, and the remaining mostly as arsenate. We conclude that arsenate is taken up by P. vittata via the phosphate transporters, reduced to arsenite, and sequestered in the fronds primarily as As(III).

Environmental context: The marine ecosystem is highly elevated in arsenic in comparison to the terrestrial environment. More than 100 different naturally occurring organoarsenic compounds have been found in different marine organisms. In order to understand how highly toxic AsHCs are formed and bioaccumulate in different marine organisms, large scale monitoring of AsHCs from a range of different laboratories is necessary. Despite their toxicity, AsHCs have not been extensively studied due in part to the lack of low-cost analytical methods and the lack of commercially available standards. Rational: This study aims to develop a new analytical method for the quantitative determination of arsenic-containing hydrocarbons (AsHCs) with gas chromatography–mass spectrometry (GC-MS). The new method is an alternative approach to determine these compounds in environmental samples. Methodology: AsHCs were extracted and purified from fish oil and seaweed samples. Due to the thermal conversion of oxo-AsHCs to their trivalent forms in the injection port of the GC, the conversion is incomplete resulting in low signal intensities and large carry overs. We therefore chemically reduced AsHCs to their trivalent forms and analysed them with GC-MS, gas chromatography–tandem mass spectrometry (GC-MS/MS) and high performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC-ICPMS). The possibility for compound independent quantification with commercially available standards was investigated. Results: After optimisation of conditions for reduction of AsHCs, these compounds could be determined in marine samples using authentic standards with the new method. Results showed good agreement with results from HPLC-ICPMS. The novel GC-MS method showed compound independent quantification using triphenylarsine (TPA) as a commercially available standard. Discussion: With the developed method we could demonstrate the applicability of GC-MS for the quantitative determination of AsHCs in marine samples for the first time. The compound independent quantification with TPA opens up a quantification for AsHCs species for which no standards are commercially available. The broad applicability might enhance screening for these toxic compounds in the environment. Environmental context. The marine ecosystem is highly elevated in arsenic in comparison to the terrestrial environment. More than 100 different naturally occurring organoarsenic compounds have been found in different marine organisms. In order to understand how highly toxic AsHCs are formed and bioaccumulate in different marine organisms, large scale monitoring of AsHCs from a range of different laboratories is necessary. Despite their toxicity, AsHCs have not been extensively studied due in part to the lack of low-cost analytical methods and the lack of commercially available standards. [ABSTRACT FROM AUTHOR]

Environmental context: Arsenic contamination has a disproportionate effect on marine ecosystems. Organisms such as some marine macroalgae, which accumulate potentially toxic elements from the surrounding environment, have developed an internal conversion process that is not yet fully understood. Are arsenic-containing sugars a product of detoxification, or simply the result of phospholipid degradation? Rationale: Arsenosugars (AsSugar) account for the majority of total arsenic in common seaweed species, yet it is unclear whether these are formed through some detoxification pathway for inorganic arsenic or are precursors/degradation products of arsenic-containing phospholipids in the cell wall. Methodology: Temporal and intra-thallus variations in water-soluble arsenic were measured by HPLC-ICP-MS, as well as total non-polar and polar arsenic-containing lipids by ICP-MS in Laminaria digitata to offer potential insight into the origins of arsenosugars. Water-soluble speciation with and without freeze-drying were also compared to determine whether freeze-drying changes the water-soluble As speciation. Results: In general, lower levels of total As were detected in the samples collected in May (39.2–74.5 mg kg−1) compared to those collected in February (72.6–151 mg kg−1). The concentration of arsenate was found to consistently increase along the thallus from the holdfast/stipe (0.78–1.82 mg kg−1) to the decaying fronds (44.4–61.0 mg kg−1) in both months, and AsSug-SO3 was the dominant AsSugar in the majority of samples. The extraction efficiency was lower in fresh samples (64–77%) than in freeze-dried (95–116%) from the same month. Water-soluble, polar AsLipids, and residual As concentrations, were generally highest in February, and the non-polar AsLipids accounted for <0.42% of totAs in all samples. Discussion: Our results suggest that the arsenosugars are not a product of arsenic detoxification, but a by-product of normal biological activity. It is probable that the arsenosugars are bound to the cell membrane within the Laminaria digitata cells, and lyophilisation is required to release them quantitatively. Future research should focus on speciation of polar lipid-soluble As extracted from fresh samples to determine if the lower extraction efficiency observed in this study is due to the As being in an unextractable form, i.e. lipids, and thus is not removed from cells during water-based extractions. Environmental context. Arsenic contamination has a disproportionate effect on marine ecosystems. Organisms such as some marine macroalgae, which accumulate potentially toxic elements from the surrounding environment, have developed an internal conversion process that is not yet fully understood. Are arsenic-containing sugars a product of detoxification, or simply the result of phospholipid degradation? [ABSTRACT FROM AUTHOR]

The symbiotic partnership of plants and fungi was a critical means of nutrient uptake during colonization of the terrestrial surface. The Lower Devonian Rhynie Chert shows evidence for extensive phosphorus mobilization in plant debris that was pervasively colonized by fungi. Sandy sediment entrapped with fungi‐rich phytodebris contains grains of the phosphate mineral monazite which exhibit alteration to highly porous and leached surfaces. Mixed manganese‐iron oxide precipitates contain up to 2% P2O5. The mobilization of Mn, Fe, and P are all features of mycorrhizal nutrient concentration. However, the ecosystem was also exposed to toxic elements from hot spring hydrothermal activity. The oxide precipitates include titanium and iron‐titanium oxide which sequestered potentially toxic tungsten and antimony. Abundant pyrite framboids in the Rhynie Chert indicate that plant decomposition included microbial sulfate reduction. This caused the removal of some of the arsenic from the groundwaters into the pyrite, which reduced toxicity while leaving enough for putative arsenic metabolism. These relationships show the mineral component of the ecosystem modified the geochemistry of ambient waters. Plain Language Summary: The symbiotic partnership of plants and fungi was a critical means of nutrient uptake during colonization of the terrestrial surface. The Lower Devonian Rhynie Chert shows evidence for extensive phosphorus mobilization in plant debris that was pervasively colonized by fungi. Sandy sediment entrapped with fungi‐rich organic matter contains grains of the phosphate mineral monazite which exhibit alteration to highly porous and leached surfaces. The ecosystem was also exposed to toxic elements from hot springs. Precipitates of oxide minerals sequestered potentially toxic tungsten and antimony. Iron sulfide allowed the removal of excess arsenic from the groundwaters. These relationships show the mineral component of the ecosystem modified the geochemistry of ambient waters. Key Points: The plant‐bearing Rhynie Chert contains authigenic mineral phases, including pyrite, and manganese‐iron and titanium oxidesAuthigenic phases may be products of bacterial and fungal components and sequestered potentially toxic elements, including As, Sb, and WDetrital monazite was leached to supply phosphate, which was required by fungi in symbiosis with plants [ABSTRACT FROM AUTHOR]

Inorganic arsenic (iAs) in 13 store-bought edible seaweed samples and 34 dried kelp ( Laminaria digitata) samples was determined by a newly developed, field-deployable method (FDM) with the aid of a field test kit for arsenic in water. Results from the FDM were compared to results from speciation analysis achieved by using high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The FDM consisted of a simple extraction method using diluted HNO to quantitatively extract iAs without decomposing the organoarsenicals to iAs followed by the selective volatilisation of iAs as arsine (AsH) and subsequent chemo-trapping on a filter paper soaked in mercury bromide (HgBr) solution. Method optimization with a sub-set of samples showed 80-94% iAs recovery with the FDM with no matrix effect from organo-arsenic species in the form of dimethylarsinic acid (DMA) on the iAs concentration. The method displayed good reproducibility with an average error of ±19% and validation by HPLC-ICP-MS showed that the results from the FDM were comparable (slope = 1.03, R = 0.70) to those from speciation analysis with no bias. The FDM can be conducted within an hour and the observed limit of quantification was around 0.05 mg kg (dry weight). This method is well suited for on-site monitoring of iAs in seaweed before it is harvested and can thus be recommended for use as a screening method for iAs in seaweed. [ABSTRACT FROM AUTHOR]

The biogeochemical cycle of arsenic (As) has been extensively studied over the past decades because As is an environmentally ubiquitous, nonthreshold carcinogen, which is often elevated in drinking water and food. It has been known for over a century that micro-organisms can volatilize inorganic As salts to arsines (arsine AsH3, mono-, di-, and trimethylarsines, MeAsH2, Me2AsH, and TMAs, respectively), but this part of the As cycle, with the exception of geothermal environs, has been almost entirely neglected because of a lack of suited field measurement approaches. Here, a validated, robust, and low-level field-deployable method employing arsine chemotrapping was used to quantify and qualify arsines emanating from soil surfaces in the field. Up to 240 mg/ha/y arsines was released from low-level polluted paddy soils (11.3 ± 0.9 mg/kg As), primarily as TMAs, whereas arsine flux below method detection limit was measured from a highly contaminated mine spoil (1359 ± 212 mg/kg As), indicating that soil chemistry is vital in understanding this phenomenon. In microcosm studies, we could show that under reducing conditions, induced by organic matter (OM) amendment, a range of soils varied in their properties, from natural upland peats to highly impacted mine-spoils, could all volatilize arsines. Volatilization rates from 0.5 to 70 μg/kg/y were measured, and AsH3, MeAsH2, Me2AsH, and TMAs were all identified. Addition of methylated oxidated pentavalent As, namely monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA), to soil resulted in elevated yearly rates of volatilization with up to 3.5% of the total As volatilized, suggesting that the initial conversion of inorganic As to MMAA limits the rate of arsine and methylarsines production by soils. The nature of OM amendment altered volatilization quantitatively and qualitatively, and total arsines release from soil showed correlation between the quantity of As and the concentration of dissolved organic carbon (DOC) in the soil porewater. The global flux of arsines emanating from soils was estimated and placed in the context of As atmospheric inputs, with arsines contributing from 0.9 to 2.6% of the global budget. [ABSTRACT FROM AUTHOR]

Macroalgae (seaweed) has been shown to be an effective environmental indicator. We investigate the trace element chemistry of macroalgae samples from locations along the Firth of Forth and Forth Estuary in Scotland. The overall trend in elemental abundance (Os ≪ Re < Ag < U < Cd < Co < Ni < Pb < Cu < As < Zn ≪ I), and changes along the estuary (seawards: increase As, I, Cd, U, Re, Os; decrease Pb, Cu; mid-estuary peak Zn; based on certain species), are controlled by a number of factors, including: salinity, mixing and macroalgal species differences. Within the same macroalgal species, some elemental abundances (As, I, Pb, Cu, Cd and U) are affected by mixing between freshwater riverine and North Sea marine saltwater. Additional mixing of natural and anthropogenic inputs from the surrounding geology and industry are also observed, affecting Zn, Ni, Co, Re and Os. Macroalgae is also an increasingly popular food, with some species harvested in the Firth of Forth. Iodine (67–5061 ppm), lead (0.047–4.1 ppm) and cadmium (0.006–0.93 ppm) macroalgal abundances are at safe levels for human consumption (WHO limits). However, many samples exceed the American (3 ppm) and Australian (1 ppm) limits for inorganic arsenic in macroalgae, with values ranging 0–67 ppm. In most of the samples, soaking and cooking the macroalgae reduced the inorganic arsenic content to within the American and Australian limits. However, this has further implications if the macroalgae is used to cook soups (e.g., Dashi), as the leached elements become a significant component of the soup. Unlabelled Image • Estuarine macroalgae elemental abundance controlled by a number of factors • Conservative and non-conservative mixing processes affect element enrichment. • Anthropogenic and geological inputs are observed. • Inorganic arsenic levels in macroalgae exceed American and Australian limits. • Levels of arsenic, iodine and others reduced in macroalgae when soaked and cooked. [ABSTRACT FROM AUTHOR]

Rice is more elevated in arsenic than all other grain crops tested to date, with whole grain (brown) rice having higher arsenic levels than polished (white). It is reported here that rice bran, both commercially purchased and specifically milled for this study, have levels of inorganic arsenic, a nonthreshold, class 1 carcinogen, reaching concentrations of ∼1 mg/kg dry weight, around 10-20 fold higher than concentrations found in bulk grain. Although pure rice bran is used as a health food supplement, perhaps of more concern is rice bran solubles, which are marketed as a superfood and as a supplement to malnourished children in international aid programs. Five rice bran solubles products were tested, sourced from the United States and Japan, and were found to have 0.61-1.9 mg/kg inorganic arsenic. Manufactures recommend ∼20 g servings of the rice bran solubles per day, which equates to a 0.01 2-0.038 mg intake of inorganic arsenic. There are no maximum concentration levels (MCLs) set for arsenic or its species in food stuffs. EU and U.S. water regulations, set at 0.01 mg/L total or inorganic arsenic, respectively, are based on the assumption that 1 L of water per day is consumed, i.e., 0.01 mg of arsenic! day. At the manufacturers recommended rice bran solubles consumption rate, inorganic arsenic intake exceeds 0.01 mg/day, remembering that rice bran solubles are targeted at malnourished children and that actual risk is based on mg kg-1 day-1 intake. [ABSTRACT FROM AUTHOR]

• We investigated simultaneous effect of Fe° and water managements on As and Cd accumulation in rice • Fe° increased percentage productive tillers and grain yield under AWD compared to that under CF. • Simultaneous use of Fe° and AWD significantly stimulated methylation of As in rice grains. • Fe° significantly inhibited Cd bioaccumulation in rice grains cultivated under AWD. Studies aiming to limit bioaccumulation of arsenic (As) and cadmium (Cd) in rice grain has attracted global attention. In this study, simultaneous impact of zero valent iron (Fe⁰) and various water management regimes (continuous flooding (CF), alternate wetting and drying (AWD) and low water (LW)) on rice grain yield (GYM) and bioaccumulation of As and Cd in unpolished rice grain (URG) were investigated. Compared to respective control treatments, Fe⁰ significantly reduced GYM under LW by 32% (p < 0.001) and significantly increased GYM under AWD by 24% (p = 0.009; F = 5.9) but had no significant effect on GYM under CF water management regime (p > 0.05). The grain harvest index was significantly higher in Fe⁰ amended rice under AWD (67%; p < 0.001) and CF (35%; p = 0.001) compared to those without Fe⁰ amendment. Fe⁰ significantly reduced tAs in URG under LW by 32% (p < 0.017) and significantly increased tAs in URG under AWD by 37% (p = 0.007) but had no significant effect on tAs in URG under CF (p > 0.05). The Cd concentrations were significantly reduced by 51% (p = 0.002) and 61% (p < 0.003) in URG under LW and AWD respectively compared to the respective control treatments. The Dimethylarsinic acid (DMA) in unpolished rice (URG) under AWD (+Fe⁰) was significantly higher (p < 0.01; F = 11.3) compared to that accumulated in URG under AWD(-Fe°). Despite increasing As accumulation in AWD water management, simultaneous use of AWD water management and Fe° increased grain yield, enhanced accumulation of less toxic methylated As in rice grains and accumulated low Cd concentrations comparable to that attainable with CF water management indicating that simultaneous use AWD and Fe° can be effective in controlling Cd accumulation in paddies highly contaminated with Cd. [ABSTRACT FROM AUTHOR]