Total Arsenic Concentrations Research Articles

Spatial patterns and environmental factors related to arsenic bioaccumulation in boreal freshwater fish

To better understand the spatial patterns in arsenic (As) bioaccumulation in freshwater systems, we investigated ecological, physical, and chemical factors associated with total arsenic concentrations ([As]) in lacustrine and riverine fish across Ontario, Canada, using a dataset of 3200 fish across 152 waterbodies. Assembled data of water chemistry, landscape characteristics, and stable carbon and nitrogen isotope ratios in muscle tissue were then used to assess factors related to As bioaccumulation. Results show that [As] were generally low across most species and waterbodies (i.e., <1 µg·g−1 wet in many inland fish). However, fish from northern coastal rivers had up to 23-fold higher [As] when compared with fish from landlocked sites. As concentrations increased slightly with the proportion of pelagic carbon in a fish's diet, although relationships varied among species and sites. Furthermore, principal component scores, representing landscape and water chemistry variables, were related to [As] in fish, but these relationships varied among species. These results will help improve the efficacy of fish contaminant monitoring by further identifying key physical and ecological variables related to higher [As] in fish.

A survey of toxic elements in ready to eat baby foods in the US market 2021

ABSTRACT A non-targeted convenience survey was conducted in 2021 to estimate the range of total arsenic (As), cadmium (Cd), total mercury (Hg) and lead (Pb) concentrations in ready-to-eat baby foods. Four hundred samples were purchased both online and in brick-and-mortar retail. Samples included both organic and non-organic products, packaged in glass or plastic jars and foil or plastic pouches. Samples were analysed by acid assisted microwave digestion and ICP-MS with an emphasis on ultra-low detection limits. Limits of quantification were 2.26, 1.31, 0.72, and 3.14 µg/kg (ppb) for As, Cd, Hg and Pb, respectively. The median concentrations of As, Cd, Hg, and Pb in tested products were 2.60, 1.81, 0.09, and 1.38 µg/kg, respectively. Foods containing rice were more likely to contain arsenic. Foods with leafy greens, such as spinach and kale, were more likely to contain cadmium and foods with root vegetables had the highest concentrations of lead.

Co-variate adjusted associations between serum concentrations of selected perfluoroalkyl substances and urinary concentrations of selected arsenic species.

Data from National Health and Nutrition Examination Survey for 2011-2012 were used to estimate associations of the serum concentrations of perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), perfluoroundecanoic acid (PFUnDA), and 2-(N-methyl-perfluorooctane sulfonamido) acetic acid (Me-PFOSA) with urinary concentrations of total arsenic (UAS), inorganic arsenic (IAS), arsenobetaine (UAB), and dimethyl arsinic acid (UDMA) among US adults aged > = 20years. Concentrations of PFNA were positively associated with all four arsenic variables but statistical significance was observed for IAS only (β = 0.33364, P = 0.04). Concentrations of PFDA were positively associated with UAS (β = 0.20688, P = 0.01), IAS (β = 0.23712, P = 0.02), and UAB (β = 0.26049, P = 0.02). Concentrations of PFUnDA were positively associated with UAS (β = 0.49946, P < 0.01), IAS (β = 0.51782, P < 0.01), UAB (β = 0.62924, P < 0.01), and UDMA (β = 0.26375, P < 0.01). Concentrations of Me-PFOSA with PFAS were inversely associated with every PFAS but statistical significance was observed for UDMA only (β = - 0.05613, P = 0.03). PFOA, PFHxS, and PFOS were, in general, negatively associated with concentrations of all four arsenic variables but without reaching statistical significance. Positive associations of PFDA, PFNA, and PFUnDA with arsenic necessitate investigation about impact of the co-exposure of these PFAS with arsenic and their impact on health. Fluorinated carbon chain length > 8 as opposed to ≤ 8 may have a role in defining associations of PFAS with arsenic.

Sediment-associated heavy metal contamination and potential ecological risk along an urban river in South Africa

Sediment contamination by heavy metals poses one of the worst environmental risks to aquatic ecosystems worldwide. The study explored sediment-associated heavy metal contamination and potential ecological risk along the Molopo River in Mahikeng, South Africa. Total concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn) were analysed using inductively coupled plasma mass spectrometry. Various indices were applied to assess the level of contamination and ecological risk. Most heavy metal concentrations at selected upstream and downstream sites were below average shale, except Cr, Cu, Hg, Pb, and Zn. The contamination factor (CF) indicates that the level of contamination was low (CF < 1) at most sampling sites, except Cr, Cu, Pb and Zn, which varied from moderate (1 CF < 3) to considerable (3 ≤ CF < 6) contamination. The enrichment factor (EF) shows that Cd, Cr, Cu, and Zn were moderate (2 EF < 5) to significantly enriched (5 EF < 20) at the affected sites. The results suggest anthropogenic enrichment (EF > 2) of Cd, Cr, Cu, and Zn. The threshold effect concentration and probable effect concentration sediment quality guidelines predicted that Cr, Cu, and Ni concentrations were more likely to have harmful effects on bottom-dwelling organisms. Pearson correlation and principal component analysis reveal that Cd, Cr, Cu, Ni, Pb, and Zn had a common anthropogenic source. We attribute the source to industrial and wastewater effluent, vehicle traffic, and runoff from various urban surfaces in the city. The study provides baseline data for heavy metal monitoring in the study area. Future research and monitoring should focus on heavy metals that cause concern because of their concentrations (Cr, Cu, Pb, and Zn) and potential ecological risk (Cr, Cu, and Ni).

Speciation and source changes of atmospheric arsenic in Qingdao from 2016 to 2020 - Response to control policies in China

Arsenic (As) is a toxic pollutant in the atmosphere. The atmospheric As concentration is high over the East Asian continent. At present, there is less research on the long-term trend of atmospheric arsenic pollution, which is not conducive to understanding its behavior. Total suspended particulate matter (TSP) samples were collected in Qingdao in autumn and winter from 2016 to 2020 to analyze total arsenic (TAs), As(V) and As(III). The interannual variation patterns, influencing factors and health risks of arsenic concentrations in aerosols were discussed. The results showed that As(V) is the dominant species of arsenic in aerosols. The average concentration of TAs gradually decreased and the proportion of As(III) increased during autumn and winter from 2016 to 2020. The levels of TAs, As(V) and As(III) in aerosols increased during the heating period and on polluted days. Negative correlation between TAs/TSP and TSP indicated that higher concentrations of TSP in the atmosphere would reduce the content of TAs in particulate matter. The increase of secondary aerosol particles played a dilution effect. Mobile source emissions, biomass and coal combustion were main sources of atmospheric arsenic. The distribution range of large potential sources of atmospheric arsenic decreased from 2016 to 2020, and concentrated, mainly in parts of Shandong province and its offshore areas. Local sources contributed the most to atmospheric arsenic pollution in Qingdao in autumn and winter. TAs, As(V) and As(III) posed a low non-carcinogenic risk and a negligible carcinogenic risk to adults and children. This study reveals the influence of strict air pollution control policies on the speciation and source of arsenic in aerosols.

Jute Fibers Synergy with nZVI/GO: Superficial Properties Enhancement for Arsenic Removal in Water with Possible Application in Dynamic Flow Filtration Systems.

Groundwater is one of the primary sources of water for both drinking and industrial use in northeastern Mexican territory, around 46% of the total, due to the lack of precipitation during the year and solar radiation index. The presence of arsenic in brackish soil and groundwater is a severe health issue, specifically in semi-arid and arid regions in the north of Mexico. Additionally, it represents the only source of drinking water in communities far from big cities, mainly due to the absence of hydric infrastructure. This work presents a new approach to treating polluted water with arsenic. The system based on activating jute fiber with nanoparticles of zero-valent iron immobilized over graphene oxide will allow nZVI particles to preserve their unique qualities for water sanitization. A dynamic flow test was designed to determine the effectivity of activated jute fibers as a water sanitation system. The results showed a reduction in the total arsenic content from 350 ppb to 34 ppb with a filtrate flow of 20 mL/min. The above represents 90% adsorption by the activated fiber. The analyzed sample corresponds to contaminated groundwater taken from Coahuila, Mexico. This sanitation system could be applied to low-income populations lacking robust infrastructure, such arsenic treatment plants.

Arsenic exposure induces urinary metabolome disruption in Pakistani male population

Millions of people are at risk of consuming arsenic (As) contaminated drinking water in Pakistan. The current study aimed to investigate urinary arsenic species [iAsIII, iAsV, dimethylarsinic acid (DMA), methylarsonic acid (MMA)] and their potential toxicity biomarkers (based on urinary metabolome) in order to characterize the health effects in general adult male participants (n = 588) exposed to various levels of arsenic in different floodplain areas of Pakistan. The total urinary arsenic concentration (mean; 161 μg/L) of studied participants was lower and/or comparable than those values reported from other highly contaminated regions, but exceeded the Agency for Toxic Substances and Disease Registry (ATSDR) limits. For all the participants, the most excreted species was DMA accounting for 65% of the total arsenic, followed by MMA (20%) and iAs (16%). The percentage of MMA detected in this study was higher than those of previously reported data from other countries. These results suggested that studied population might have high risk of developing arsenic exposure related adverse health outcomes. Furthermore, random forest machine learning algorithm, partial correlation and binary logistic regression analysis were performed to screen the arsenic species-related urinary metabolites. A total of thirty-eight metabolites were extracted from 2776 metabolic features and identified as the potential arsenic toxicity biomarkers. The metabolites were mainly classified into xanthines, purines, and amino acids, which provided the clues linking the arsenic exposure with oxidative stress, one-carbon metabolism, purine metabolism, caffeine metabolism and hormone metabolism. These results would be helpful to develop early health warning system in context of arsenic exposure among the general populations of Pakistan.

Arsenic removal using electrocoagulation followed by hematite granular filter

Abstract Drinking water contaminated with arsenic is a threat to human health. The present study attempts to remove arsenic using electrocoagulation with iron electrodes (ECFe) in continuous flow mode. Two experimental runs were separately conducted using untreated and treated (acid treatment followed by pH neutralization step) hematite as granular bed. The treatment of the hematite formed ferric oxy-hydroxides on hematite surface which was beneficial for arsenic removal. Total arsenic concentration reduced below 10 ppb from initial concentration of 500 ppb [As(III): As(V) = 1:1] with Fe dose of 5 mg/L after 48 h and 2 h of run conducted with untreated and treated hematite granular bed, respectively. The required Fe/As ratio of 10 was much lesser than the reported requirement of 250 in conventional systems. In the filter prototype using market-available filter cartridge, arsenic concentration reduced below 10 ppb from an initial concentration of 500 ppb [As(III): As(V) of 1:1] in both the absence and presence of phosphate (2 ppm) and silicate (30 ppm).

Species composition and health risk assessment of arsenic in Agaricus blazei Murrill and Tricholoma matsutake from Yunnan Province, China

High concentrations of total arsenic (As) has been found in Agaricus blazei Murrill and Tricholoma matsutake samples. It is important to study the As species in A. blazei and T. matsutake for accurate health risk assessment. Total As was measured by inductively coupled plasma-mass spectrometry (ICP-MS). An analytical method was developed to determine As species in mushroom by using anion exchange and cation exchange chromatography coupled to ICP-MS. Total As contents ranged from 5.25 to 69.5 mg kg1. Arsenobetaine (AsB), inorganic arsenic (iAs), and monomethylarsenic acid (MMA) were the main form of As in A. blazei samples, which accounted for 42.7–88.8 %, 1.59–26.2 %, and 0.74–1.12 % of the extractable As, respectively. AsB, and dimethylarsenic acid (DMA) were the main form of As in T. matsutake samples, which accounted for 88.9–97.9 %, and 1.79–3.80 % of the extractable As, respectively. Arsenocholine (AsC), trimethylarsine oxide (TMAO), and tetramethylarsonium cation (TMA+) were present as well, but only at trace concentrations. The health risk index estimation results indicated that no particular risk of iAs exposure to consumers existed in T. matsutake. The iAs exposure in A. blazei can poses certain health risks.

Highly efficient in-situ purification of Fe(II)-rich high-arsenic groundwater under anoxic conditions: Promotion mechanisms of PMS on oxidation and adsorption

Dissolved Fe(II) widely exists in high-arsenic (high-As) groundwater, whose concentration (12–518 µM) is positively correlated with that of As(III). In order to realize the environmental-friendly and highly efficient in-situ simultaneous oxidation and adsorption of As(III) under anoxic conditions, peroxymonosulfate (PMS) was directly dosed into Fe(II)-rich high-As groundwater. Compared with hydrogen peroxide (88.2%) and peroxydisulfate (66.6%), the involvement of PMS gave the best As(III) removal efficiency of 98.8% after 1 min treatment, owing to the dual aspects of the best oxidation of As(III) and the best adsorption of As(V). During As(III) oxidation process, more SO4•− and 1O2 generated and unactivated PMS in Fe(II)-PMS process were responsible for the most efficient oxidation. During the enhanced As(V) adsorption process, the presence of PMS changed the structure of the in-situ formed Fe(III) colloid to provide more adsorption sites. Besides, the higher PMS concentration caused better As(III) oxidation, As(III) immobilization, and As(V) adsorption efficiencies. A wide range of Fe(II) (125–500 µM) coupled with PMS (244 µM) could immobilize more than 90% of As(III) (C0 = 1000 µg/L), and As(III) ranging from 0.2 mg/L to 2.0 mg/L also could be removed over 90% in Fe(II)-PMS process. The coexistence of HCO3–, Cl−, and humic acid slightly affected As(III) immobilization. Furthermore, after treatment, residual Fe ions concentration, residual total arsenic concentration, sulfate ions concentration, and pH value met the drinking water standard. This study could provide a very promising and attractive technology for a fast and efficient in-situ purification of Fe(II)-rich high-As groundwater.

Arsenosugar extracted from algae: Isolation by anionic exchange solid‐phase extraction

Obtaining reliable speciation data for evaluating dietary exposure, and increasing understanding of arsenic biochemistry in algae, are hindered by the availability of suitable standards of arsenosugars, the major species in these types of samples. Moreover, chemical syntheses of such compounds have been reported to be complex and tedious. The aim of this work was to investigate the feasibility of the anionic exchange SPE cartridges (SAX and WAX) as an easy and quick alternative for the isolation and preconcentration of arsenosugars. Two commercial silica-based SPE cartridges strong anion exchange sorbent (DSC-SAX) and weak anion exchange sorbent (DSC-NH2) were compared for the SPE of three arsenosugars (PO4-Sug, SO3-Sug and SO4-Sug). The effect of pH, ionic strength, type of salt and elution solvent on the elution protocols of these arsenosugars are studied. Eluted solutions from SPE were analyzed by ICP-MS for total arsenic content and IC-ICP-MS for the study of arsenic speciation.The developed SPE procedure allows to obtain a solution containing the three arsenosugars isolated from other arsenic species with recoveries over 75% for SO3-Sug and SO4-Sug, whereas for PO4-Sug were around 45%.

Identification of Microcrustaceans as Potential Bioindicators of Arsenic in Tropical Water Bodies.

We investigated microcrustaceans inhabiting arsenic contaminated and non-contaminated freshwater to identify potential bioindicators of arsenic contamination in the tropical freshwater of Matehuala in northern Mexico. We collected water, sediment, and zooplankton, at five sampling points during three sampling campaigns. We determined water temperature, pH, electrical conductivity, dissolved oxygen, alkalinity, salinity, and total arsenic concentration in water. Additionally, we determined total arsenic and arsenic speciation in sediment samples. We identified microcrustaceans and determined abundance, richness, and Shannon Index. We also investigated relationships and correlations between physiochemical and ecological variables. Results showed that arsenic concentrations in freshwater ranged from 0.001 to 53.23mg/L, while total arsenic in sediments ranged from 10.37 to 2472.84mg/kg as As + 5. Six microcrustacean species were found in highly and moderately contaminated water (Latonopsis australis, Eucyclops chihuahuensis, Acanthocyclops americanus, Pleuroxus (Picripleuroxus) quasidenticulatus, Macrocyclops albidus, and Paracyclops chiltoni), while five species were found in arsenic-free water (Simocephalus punctatus, Alona glabra, Eucyclops leptacanthus, M. albidus, and P. quasidenticulatus). An inverse relationship was observed between microcrustacean richness and arsenic. However, the scope of the data did not allow for a strong and significant correlation. Nevertheless, among the species inhabiting As-free water, S. punctatus showed potential to be further tested as a bioindicator of As contamination in Matehuala. Identification of potential bioindicators could help monitor water quality and increase understanding of the incorporation and toxicity of As in freshwater-sensitive and freshwater-metallotolerant microcrustaceans, which, in turn, might help us to understand As incorporation in the food web.

Exposure of the Portuguese population to metals and metalloids: results from a national study

Metals and metalloids are elements present in the environment that can originate from natural and anthropogenic sources. However, exposure to some of these elements can cause adverse health effects due to their toxicological potential. As such, it is important to assess their levels in the human body, which can be done through human biomonitoring. Several studies assessed these elements’ levels in the Portuguese population, but were mainly focused on hotspots or specific groups. As such, the aim of this work was to assess the exposure to metals and metalloids in the Portuguese population using samples collected in the study &amp;#x22;Exposure of the Portuguese Population to Environmental Chemicals: a study nested in INSEF 2015&amp;#x22; (INSEF-ExpoQuim). INSEF-ExpoQuim was an epidemiologic study including 297 participants aged 28-39 years, living in Portugal for &amp;#x2265; 12 months and able to follow an interview in Portuguese. Fieldwork was developed between June 2019 and February 2020 following the guidelines of the HBM4EU project. First morning urine samples were collected along with data on sociodemographic characteristics, living conditions and residential history, habits/lifestyle, nutrition, health, occupation and substance specific information. Total concentrations of arsenic (As), lead (Pb), cobalt (Co), copper (Cu), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se) and zinc (Zn) were determined by inductively coupled plasma mass spectrometry. As, Cu, Mo, Se and Zn were detected in the majority of the samples analysed, while Mn was detected in around half and Pb, Co and Ni were detected in less than half. Results will be presented, including a description of the biomarkers’ levels in the Portuguese population. This study is the first developed in Portugal to provide an assessment of the exposure at a national level and its results may support the development and implementation of policy measures aimed at minimizing exposure and improving the population’s health.

Dashboard charting for online compliance monitoring of heavy metals in school-meal chicken and pork in Taiwan

The use of dashboard monitoring is increasingly desirable for modern food safety management. Therefore, a customized dashboard was developed with three components: Traceable timing chart, Violation Table, and Statistical Table. Raw and cooked chicken (n = 84) and pork samples (n = 96) were taken from a major school-meal supplier in central Taiwan for ten months. The concentrations of lead (Pb), cadmium (Cd), total mercury (tHg) and total arsenic (tAs) were analyzed. Pb and tAs were detected in 12 – 46% and 73 – 76 % of samples, respectively, while Cd and tHg were detected at levels of minor concern. For the geometric mean, Pb, Cd, Hg and tAs were detected at 17.6, < LOD, 5.5 and 27.6 μg/kg in raw chicken, respectively, and at 12.1, 7.0, 5.9 and 13.3 μg/kg in raw pork, respectively. Fried and grilled samples had higher detection rates and concentrations than their uncooked samples. Pb was close to that reported in literature. Total arsenic was detected at a noticeably higher amount than the geometric mean (3 μg/kg) reported in the United States. The monitoring results of raw samples were in compliance with the regulations. Of all the samples, only two cooked chicken samples exceeded the regulatory standard of Pb (100 μg/kg).

Arsenic species in mesopelagic organisms and their fate during aquafeed processing.

A responsible harvest of mesopelagic species as aquafeed ingredients has the potential to address the United Nations Sustainable Development Goal 14, which calls for sustainable use of marine resources. Prior to utilization, the levels of undesirable substances need to be examined, and earlier studies on mesopelagic species have reported on total arsenic (As) content. However, the total As content does not give a complete basis for risk assessment since As can occur in different chemical species with varying toxicity. In this work, As speciation was conducted in single-species samples of the five most abundant mesopelagic organisms in Norwegian fjords. In addition, As species were studied in mesopelagic mixed biomass and in the resulting oil and meal feed ingredients after lab-scale feed processing. Water-soluble As species were determined based on ion-exchange high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). This was supplemented by extracting arsenolipids (AsLipids) and determining total As in this fraction. The non-toxic arsenobetaine (AB) was the dominant form in mesopelagic crustaceans and fish species, accounting for approximately 70% and 50% of total As, respectively. Other water-soluble species were present in minor fractions, including carcinogenic inorganic As, which, in most samples, was below limit of quantification. The fish species had a higher proportion of AsLipids, approximately 35% of total As, compared to crustaceans which contained 20% on average. The feed processing simulation revealed generally low levels of water-soluble As species besides AB, but considerable fractions of potentially toxic AsLipids were found in the biomass, and transferred to the mesopelagic meal and oil. This study is the first to report occurrence data of at least 12 As species in mesopelagic organisms, thereby providing valuable information for future risk assessments on the feasibility of harnessing mesopelagic biomass as feed ingredients.

The effect of rock lithology on the background concentrations of trace elements in alluvial soils: Implications for environmental regulation

To assess the extent of soil contamination with a potentially toxic element, it is important to determine the background concentration of that element in the soil. In this study we decided to investigate the relationship between trace element concentrations in soils and the lithology of their parent rocks. We collected 85 topsoils (0–20 cm) samples from the Petorca, La Ligua, Aconcagua, and Casablanca River basins (Valparaiso region, central Chile). For soil sampling, we chose 11 tributary watersheds free of anthropogenic influence. The areas that contributed to the formation of each alluvial soil were delineated and the parent lithologies were acquired from 1:250,000 geological maps. The results show that the total concentrations of arsenic (As), copper (Cu), lead (Pb), and zinc (Zn) in soil vary considerably among the four river basins studied. Soil concentrations of all elements under study are positively correlated with the presence of andesitic volcanic rocks. Furthermore, soils formed from marine sediments and felsic volcanic rocks had the highest concentrations of Pb and As. The carbonate-bearing marine sediments may have adsorbed As and Pb released by weathering of felsic volcanic rocks found upstream of the study area. In contrast, lithologies dominated by continental sedimentary and plutonic rocks showed negative correlations with the concentrations of As, Cu, Pb, and Zn in the soil. Thus, the differences in soil element concentrations in the watersheds under study were due to the different rock types present in the area. We argue that absolute “one-limit-fits-all” background trace element values may be inadequate to assess the extent of soil contamination. Therefore, it is important to determine background concentrations of soil elements in each river basin in the anthropogenically impacted areas. In contrast, erroneous conclusions can be drawn when background concentrations are determined in one region and then applied in another region that is lithologically different.

The speciation of arsenic in the muscle tissue of inland and coastal freshwater fish from a remote boreal region

Elevated concentrations of total arsenic (As) have been reported in boreal freshwater fish in both human-impacted and relatively pristine areas. We assessed the arsenic speciation profiles in muscle tissue of six fish species (n = 300) sampled from nine locations across a remote freshwater watershed in northern Ontario, Canada, extending from inland headwater lakes to the coastal marine confluence. Of the five arsenic species measured, only arsenobetaine (AsB) and dimethylarsinic acid (DMA) were detected in these fish. Riverine fish had up to 10-fold higher total [As] when compared to lacustrine fish. On average, these riverine fish also had higher percentages of AsB (%AsB, 60 ± 26%) and lower percentages of unmeasured arsenic (%UNM, 20 ± 21%), compared to lacustrine fish (28 ± 18% and 52 ± 21% %AsB and %UNM, respectively). DMA percentages (%DMA) were relatively consistent across the watershed, averaging 20 ± 21% across all fish. We examined ecological drivers of As speciation and found that %AsB increased slightly with fish weight in large-body predatory fish, but not in forage fish or insectivores. Furthermore, %AsB was positively related to trophic elevation (inferred from δ15N) in lacustrine fish across 3 out of 4 communities and within some populations. Lastly, riverine fish with a more marine-based diet had markedly higher %AsB when compared to fish with more freshwater-based diets, indicating an effect of anadromy on arsenic speciation. Overall, knowledge on arsenic speciation in freshwater fish has been limited and these results indicate potential drivers that can be considered in future studies. Furthermore, the absence of toxic inorganic As species in these boreal fish is an important consideration for future environmental monitoring practices and risk assessments, some of which assume 10–20% of total [As] in fish is present as toxic inorganic As. Additional studies on As bioaccumulation and biotransformation are needed in freshwater systems, particularly at the base of aquatic food webs.

Study on the Absorption of Arsenic Species in Realgar Based on the Form and Valence.

At present, several experiments have been carried out to study the changes in total arsenic content of realgar and its prescription, but few researches on its form and valence. We evaluated the change in arsenic species concentration in realgar from the perspective of absorption by using an in vitro dissolution study, an in vivo unidirectional intestinal perfusion study, transmembrane transport in Caco-2 cells, and a pharmacokinetic study in rats. In the gastrointestinal tract, arsenic species are mainly present inorganic forms of AsIII and AsV. The cumulative dissolution rates of soluble arsenic in 4 h artificial gastric fluid and 8 h artificial intestinal fluid were 21.99% and 59.20%, respectively. The Papp values of soluble arsenic in realgar in the duodenum, jejunum, and ileum of rats were 5.4 × 10−3, 6.1 × 10−3 and 5.8 × 10−3 cm/min, respectively. In the process of small intestine perfusion, the AsIII of realgar was partially converted into AsV in the duodenum and jejunum. As the transport time increased, the transmembrane transport rate and Papp value of soluble arsenic in realgar were increased in Caco-2 cells, and it also suggested that arsenic species may be passively transported across the Caco-2 cell monolayer. The Cmax and AUC (0-24) of AsIII, AsV, and DMA in plasma of realgar were 41.26 ng L−1/343.977 ng h mL−1, 21.626 ng L−1/47.310 ng h mL−1, and 2.372 ng L−1/30.429 ng h mL−1, respectively. Tmax and MRT (0-∞) of AsIII, AsV, and DMA were 2.571 h/9.649 h, 0.393 h/2.790 h, and 3.143 h/23.145 h, respectively. It is hoped to provide a basis for clarifying the arsenic species in realgar.

Postmortem reference concentrations of elements in blood and urine

To establish postmortem reference concentrations of elements. Fatal intoxications, both accidental and intentional, are a global issue. In the western world intoxications with pharmaceuticals dominate, but in other parts of the world other substances are more common. Intoxication with elemental compounds is generally considered to be uncommon. In a forensic setting, elemental intoxications are of great importance when investigating both accidental, suicidal, and homicidal deaths. Arsenic, for example, is a classical poison which also has relevance in the modern era. Unlike for pharmaceuticals, postmortem reference concentrations for elements are scarce. For many elements it is therefore unknown if, and to what extent, they are affected by postmortem redistribution. The current study presents normal postmortem reference concentrations of 68 elements in femoral blood and urine. In addition, possible sources of error such as contamination from collection tubes, preservative potassium fluoride solution and storage time are evaluated. Paired blood and urine samples from 120 cases of death by suicidal hanging in Sweden were collected. 20 cases from each of the six local units of forensic medicine were used to account for possible regional differences. Additionally, the included cases reflected both short and long storage times. To account for possible elemental contamination from collection tubes and the added potassium fluoride solution, multiple batches of tubes and multiple samples of potassium fluoride solution were also analysed. Concentrations of elements were determined by double focusing sector field ICP-MS. Key descriptive statistics for all 68 elements are provided (including mean, median and percentiles) in blood and urine. Forensic highlights include blood concentrations of total arsenic (mean: 4.25 μg/g), thallium (mean: 0.14 μg/g) and antimony (mean: 14.82 μg/g). For several elements in blood and urine ( n = 24 and n = 25, respectively) a majority of elemental concentrations were below the limit of detection. The contribution of contamination from collection tubes were minor compared to the overall mean elemental concentrations in both blood and urine. Though the added solution of potassium fluoride contained a large assortment of elements, given the small amounts of this solution added to samples, the overall contribution is minor for most elements relative to the overall mean. However, there was a significant difference between samples with short and long storage time for 22 elements in blood and 17 elements in urine. These differences reflected both increases and decreases in concentration. Relative to antemortem elemental concentrations the postmortem concentrations show both increases and decreases. Of special note are markedly higher concentrations for several elements in blood (such as cadmium, chromium, manganese and antimony) compared to several antemortem populations. In general, it can be assumed the phenomenon of postmortem redistribution is as large for elements as it is for drugs and other substances. When evaluating individual concentrations, it is important to be aware of potential sources of contamination and the potential influence of storage time. Concentrations indicating overexposure must be evaluated together with autopsy findings and case circumstances to form a holistic view of the case as a whole. The present study provides an important tool when evaluating postmortem elemental concentrations. It fills a needed gap between large antemortem population studies and postmortem case reports or small case series of elemental intoxications. Together with the forensic autopsy and circumstantial information the present references will aid in diagnosing cases of potential elemental overexposure.

Influence of geological faults on dissolved arsenic concentrations in an overexploited aquifer with shallow geothermal heat

Hydrochemical and mineralogical analyses were performed to identify the main processes that contribute to the concentration of total inorganic arsenic (iAs) in groundwater within the northern portion of the Laguna Seca aquifer in Guanajuato State, Mexico. The spatial extent of the study area spans across a large graben with pore-waters that contain the highest dissolved arsenic concentrations in the basin. This scale of study was chosen to test the hypothesis that normal faults act as conduits for rising geothermal waters carrying arsenic into the shallow aquifer that has been historically depressurized by irrigation pumping. The arsenic content in outcrops ranged from 3.5 to 19.5 ppm. The major minerals are quartz, plagioclase, micas, and zeolites. Multivariate cluster and Principal Components Analyses on the chemical composition and temperature of 15 wells in the study area suggest that silicate weathering is the dominant water-rock interaction that explains the observed concentrations of major ions and arsenic in groundwater. The sampled irrigation and municipal wells ranged from 190 to 550 m in depth and had temperatures ranging from 28.3 to 45.2 °C. Cluster II had the highest temperature, and greatest mineralization (total dissolved solids), and it was more influenced by regional flow than Cluster I. The concentration of iAs ranged from 16 to 229 μgL−1, all of the samples exceeded the maximum concentration suggested by the World Health Organization (10 μgL−1). Four samples belonging to Cluster II exceeded the maximum concentration set by Mexican regulations (25 μgL−1) by at least five times. The highest concentration of arsenic in surface rock coincides spatially with Cluster II wells. Geothermal heat and long pore-water-residence times enables the dissolution of silicate minerals which increases the pH (from 7.3 to 9.1) and consequently drives desorption of arsenic from mineral surfaces. During the dry season the iAs content increased in all wells from 6 to 138 μgL−1 compared to the wet season. This could be attributed to the increase in pumping that occurs then. The close proximity of Cluster II wells to newly mapped faults within the graben supports the hypothesis that Cluster II wells intercept regional groundwater flow that ascends through those previously unmapped faults.