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Speciation of arsenic in biological samples
Abstract
Speciation of arsenicals in biological samples is an essential tool to gain insight into its distribution in tissues and its species-specific toxicity to target organs. Biological samples (urine, hair, fingernail) examined in the present study were collected from 41 people of West Bengal, India, who were drinking arsenic (As)-contaminated water, whereas 25 blood and urine samples were collected from a population who stopped drinking As contaminated water 2 years before the blood collection. Speciation of arsenicals in urine, water-methanol extract of freeze-dried red blood cells (RBCs), trichloroacetic acid treated plasma, and water extract of hair and fingernail was carried out by high-performance liquid chromatography (HPLC)-inductively coupled argon plasma mass spectrometry (ICP MS). Urine contained arsenobetaine (AsB, 1.0%), arsenite (iAs(III), 11.3), arsenate (iAs(V), 10.1), monomethylarsonous acid (MMA(III), 6.6), monomethylarsonic acid (MMA(V), 10.5), dimethylarsinous acid (DMA(III), 13.0), and dimethylarsinic acid (DMA(V), 47.5); fingernail contained iAs(III) (62.4%), iAs(V) (20.2), MMA(V) (5.7), DMA(III) (8.9), and DMA(V) (2.8); hair contained iAs(III) (58.9%), iAs(V) (34.8), MMA(V) (2.9), and DMA(V) (3.4); RBCs contained AsB (22.5%) and DMA(V) (77.5); and blood plasma contained AsB (16.7%), iAs(III) (21.1), MMA(V) (27.1), and DMA(V) (35.1). MMA(III), DMA(III), and iAs(V) were not found in any plasma and RBCs samples, but urine contained all of them. Arsenic in urine, fingernails, and hair are positively correlated with water As, suggesting that any of these measurements could be considered as a biomarker to As exposure. Status of urine and exogenous contamination of hair urgently need speciation of As in these samples, but speciation of As in nail is related to its total As (tAs) concentration. Therefore, total As concentrations of nails could be considered as biomarker to As exposure in the endemic areas.
... One limitation of the toenail matrix is that conventional analysis is limited to measurement of total As. Extraction of As species from the nail or hair matrix is labor intensive, could lead to interconversion of As species and is not amenable to the number of samples encountered in an epidemiological study[28]. Studies that have measured As species in nail and hair samples report that the majority of As in the hair and nail matrix reflects inorganic As[28,29]. The most common As biomarker of exposure is urine and reflects recent exposures[30]. ...
... Extraction of As species from the nail or hair matrix is labor intensive, could lead to interconversion of As species and is not amenable to the number of samples encountered in an epidemiological study[28]. Studies that have measured As species in nail and hair samples report that the majority of As in the hair and nail matrix reflects inorganic As[28,29]. The most common As biomarker of exposure is urine and reflects recent exposures[30]. ...
... A simple sample dilution preparation coupled with chromatography enables analysis of inorganic As, As metabolites and organoarsenic compounds. Inorganic and organic As species in urine samples have been measured using a hyphenated technique that couples high performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP-MS)[3,28,[31][32][33][34][35]. As speciation measurements have also been made by coupling liquid chromatography to hydride generation atomic absorption spectrometry (LC-HG AAS)[36], ion exchange chromatography coupled to hydride generation atomic fluorescence spectrometry (LC-HG-ICP-AFS)[37,38]and hydride generation inductively coupled plasma mass spectrometry (HG-ICPMS)[39]. ...
The speciation analysis of As in urine samples can provide important information for epidemiological studies. Considering that these studies involve hundreds or thousands of samples, a fast and reliable method using a simple LC system with short-length mixed bed ion exchange chromatographic column coupled to ICP-MS for As speciation in human urine samples was developed in this work. Separation of AB+TMAO, DMA, AC, MMA and AsIII + AsV was accomplished within 5 min with good resolution when ammonium carbonate solutions were used as mobile phases and H2O2 was added to samples to quantitatively convert AsIII to AsV. Repeatability studies yielded RSD values from 2.0 – 4.8% for all species evaluated. Limits of detection (LOD) for As species ranged from 0.003 – 0.051 ng g⁻¹. Application of the method to human urine samples from a non-contaminated area showed that the sum of species measured corresponded to 62–125% of the total As in the sample. The recovery values for these species in urine SRM 2669 were in the range of 89–112% and demonstrated the suitability of the proposed method for epidemiological studies.
... The participants had around 3-4 times higher concentrations of As in the cellular fraction than in plasma. Similar results were observed in Japan and Germany among subjects without occupational exposure [14,41], while 72 % was found in erythrocytes in subjects with little seafood consumption exposed mainly through drinking water in Bangladesh [42]. Data on speciation of As in erythrocytes of humans are sparse. ...
... Data on speciation of As in erythrocytes of humans are sparse. Mandal et al. [42] reported 22.5 % arsenobetaine and 77.5 % DMA in erythrocytes, but only 12.6 % of the As content was recovered. Also Shibata et al. [43] reported the presence of arsenobetaine in human erythrocytes. ...
Background:
Humans are exposed to inorganic and organic arsenic. The total arsenic (As) concentration in urine is a commonly used biomarker of exposure. However, little is known about variability of As in biological fluids and the diurnal variation of As excretion.
Objectives:
Main objectives were to assess the variability of As in urine, plasma (P-As), whole blood (B-As), and the blood cell fraction (C-As), and to assess diurnal variation of As excretion.
Methods:
Six urine samples were collected at fixed times during 24 h on two different days around one week apart among 29 men and 31 women. Blood samples were collected when the morning urine samples were delivered. The intra-class correlation coefficient (ICC) was calculated as the ratio of the between-individuals variance to the total observed variance.
Results:
Geometric mean (GM) 24 h urinary excretions of As (U-As24 h) were 41 and 39 µg/24 h on the two days of sampling. Concentrations of B-As, P-As and C-As were highly correlated with U-As24 h and As in first void morning urine. No statistically significant differences were observed for the urinary As excretion rate between the different sampling times. A high ICC was observed for As in the cellular blood fraction (0.803), while ICC for first morning urine corrected for creatine was low (0.316).
Conclusions:
The study suggests that C-As is the most reliable biomarker for use in exposure assessment of individual exposure. Morning urine samples have low reliability for such use. No apparent diurnal variation was observed in the urinary As excretion rate.
... In studies of non-pregnant adults, ICCs for repeated urinary arsenic measures ranged from 0.35 to 0.49 for inorganic species [69,70]. Urinary biomonitoring data are also potentially influenced by the time of collection, preservation methods, and transportation [71]. Urinary arsenic tends to be dominated by DMA. ...
... As V 33.2%, MMA V 2.2%, DMA V 3.6%) yet no detectable DMA III [101]. Hair may be more reflective of iAs than metabolites as it has been shown to adsorb 9-13% As III , and 12-16% As V [71]. Both toenail and hair concentrations are distal to the target organs of interest [88]. ...
Exposure assessment of inorganic arsenic is challenging due to the existence of multiple species, complexity of arsenic metabolism, and variety of exposure sources. Exposure assessment of arsenic during pregnancy is further complicated by the physiological changes that occur to support fetal growth. Given the well-established toxicity of inorganic arsenic at high concentrations, continued research into the potential health effects of low-level exposure on maternal and fetal health is necessary. Our objectives were to review the value of and challenges inherent in measuring inorganic arsenic species in pregnancy and highlight related research priorities. We discussed how the physiological changes of pregnancy influence arsenic metabolism and necessitate the need for pregnancy-specific data. We reviewed the biomonitoring challenges according to common and novel biological matrices and discussed how each matrix differs according to half-life, bioavailability, availability of laboratory methods, and interpretation within pregnancy. Exposure assessment in both established and novel matrices that accounts for the physiological changes of pregnancy and complexity of speciation is a research priority. Standardization of laboratory method for novel matrices will help address these data gaps. Research is particularly lacking in contemporary populations of pregnant women without naturally elevated arsenic drinking water concentrations (i.e. <10 µg/l).
... high toxic arsenic specie MMA III but not DMA III was detectable in the biological samples such as urine, blood, hair, nails and saliva from APL patients as shown in Fig. 2, implying that MMA III might be responsible for arsenic-induced toxicity. Furthermore, we compared the methylated arsenic species in biological samples from APL patients receiving ATO treatment (relatively high levels) and general population in arsenic affected area (relatively low levels) (Wang et al., 2004;Chen et al., 2018aMandal et al., 2004), as shown in Table 1. Interestingly, methylated arsenic species in APL patients were comparatively lower than general population in arsenic affected area, indicating that generation of methylated arsenic species can be inhibited by high levels of ATO in APL patients (Mandal et al., 2004). ...
... Furthermore, we compared the methylated arsenic species in biological samples from APL patients receiving ATO treatment (relatively high levels) and general population in arsenic affected area (relatively low levels) (Wang et al., 2004;Chen et al., 2018aMandal et al., 2004), as shown in Table 1. Interestingly, methylated arsenic species in APL patients were comparatively lower than general population in arsenic affected area, indicating that generation of methylated arsenic species can be inhibited by high levels of ATO in APL patients (Mandal et al., 2004). Thus, we assumed that decreasing of methylated arsenic species inhibited the apoptosis, while massive amount of iAs III induces excessive cellular differentiation, probably resulting in the production of numerous maturating meyloid cells and development of DS in some APL patients. ...
Arsenic trioxide (ATO) has a long history and it is recognized as both poison and drug for more than two thousand years. Since the establishment of ATO as a frontline therapeutic agent for acute promyelocytic leukemia (APL), the survival of APL patients have been greatly improved and APL is turned from highly fatal to highly curable disease. Mechanistically, ATO can induce PML/RARα fusion protein degradation, causing APL cell differentiation and apoptosis. On the other hand, the side effects such as differentiation syndrome, cardiac conduction abnormalities and liver toxicity are often observed during the ATO treatment of APL in clinic. It is likely that the therapeutic and adverse effects of ATO is probably associated with its distinct pattern of metabolism and direct or indirect effects on different organs. In this review, we provided a comprehensive and in-depth elaboration of the cytotoxic mechanisms of ATO and its methylated metabolites based on in vivo or in vitro studies, trying to clarify the importance of achieving balance between the toxicity and anti-leukemic activity of ATO in APL treatment.
... 91 Nail-clippings are therefore regarded as valuable biomarkers for such exposures. 93,94 The FINBAR (Factors Influencing Barrett's Adenocarcinoma Relationship) study group attempted to correlate trace element status in toenails with the risk of Barrett's oesophagus and oesophageal adenocarcinoma. 91 Toenail clippings from 638 participants and healthy controls were analyzed for eight trace elements. ...
... Further, external contamination of nails with arsenic is much less extensive compared to that of hair. 94 Long-term exposure to arsenic can lead to adverse health effects 95, 96 Lu et al. concluded that high arsenic exposure in humans promotes cancer initiation, 97 though the exact mechanism of arsenic's role in carcinogenesis remains unknown. 98, 99 Mechanisms responsible for arsenic accumulation in nails are poorly understood. ...
The nail is an important skin appendage, but not many dermatologists are aware of the importance it receives outside our specialty. This article focuses on the nail in non-dermatological contexts. The nail is a keratinized matrix capable of continuous growth with the ability to incorporate various compounds within its structure. Therefore it can be used to monitor long-term consumption of drugs. It is also an excellent source of germ-line DNA for genetic analyses. With an increased undrstanding of nail physiology, there is now a better understanding of its connection to various pathologies as well. Nails, being peripherally placed, are easy to sample without significant discomfort to the patient, making them a valuable diagnostic tool. For this narrative review, we carried out a PubMed search using the key words "nail clipping," "nail DNA," "nail diabetes mellitus;" "nail clipping oncology," and "nail forensics". Retrieved articles were searched for information pertaining to non-dermatologic uses of nail for evaluation, which is presented in a narrative fashion. It is clear from recent literature that the nail is not just an inert skin appendage, but a dynamic window into the ever-changing metabolic and genetic milieu. We highlight the numerous roles of nail specimens, as well as point towards future research needed therein.
... There are now many published ICP-MS methods for measuring As metabolites in urine. (219)(220)(221)(222)(223)(224)(225)(226)(227)(228)(229)(230)(231)(232)(233)(234)(235)(236)(237) Several reviews describe methods and applications for As speciation in clinical samples. (238)(239)(240)(241) LC-ICP-MS has been compared to LC-HG-atomic fluorescence spectrometry (AFS) (220,226,242) and to HG-AAS (220) for measuring iAs and As metabolites in urine. ...
Atomic absorption spectrometry (AAS) and optical emission spectrometry (OES) are two closely related instrumental techniques that have many applications in many different fields. In clinical chemistry, these techniques are well established for the quantitative measurement of essential and nonessential elements found in body tissues and fluids. For most practical purposes, the elements that are routinely measured with modern commercial instrumentation include almost all of the metallic elements of the s, d, and p blocks of the periodic table. The exceptions in the p block include the halogens, the noble gases, and the elements C, H, N, O, and S. Above atomic number 83 (Bi), only U is measured in absorption. Over the last two decades, the increasing use of inorganic mass spectrometry in clinical laboratories has opened up new possibilities and commercial instrumentation based on inductively coupled plasma mass spectrometry (ICPMS) is now the dominant technique. Clinical chemists are now able to measure the multielement composition of biological specimens at ultra‐trace concentrations, i.e. <10 μg L ⁻¹ . With ICPMS, the halogens become detectable, along with B, C, N, and Th. The coupling of ICPMS with separation technologies has opened up new possibilities in clinical laboratory medicine in the field of chemical speciation analysis. In some areas of clinical chemistry, older atomic spectrometric techniques may still be considered the reference method for selected clinical applications, e.g. the determination of serum K and serum Na by flame atomic emission spectrometry ( FAES ). In other areas, flame atomic absorption spectrometry (FAAS) remains feasible for serum Mg and serum Cu because of its sensitivity, rapid throughput, and the relatively low cost of instrumentation. Graphite furnace atomic absorption spectrometry (GFAAS), also known as electrothermal atomic absorption spectrometry ( ETAAS ), while more complex than flame atomization methods, is still fit for purpose for routine applications such as blood Pb and serum Al, where physiological concentrations are too low to be measured in the flame without laborious preconcentration efforts. Robust procedures for quality assurance (QA) and quality control (QC) are now well established within the clinical laboratory and cover the entire spectrum of clinical laboratory activities. These include preanalytical issues, personnel training, and education, and also the appropriate use of certified reference materials (CRMs) for method validation purposes. Participation in proficiency testing (PT) programs and external quality assessment schemes (EQAS) for trace elements in biological fluids have also contributed to improved clinical laboratory performance. Despite the advent of ever more sensitive techniques and robust procedures, the quality of results is still only as good as the specimen collected. Contamination can occur at the preanalytical stage of the analysis and also during the analysis. Selection of the appropriate specimen is critical to obtaining meaningful clinical information about nutritional trace element status or exposure to toxic elements.
... A study found arsenic was metabolically bio-transformed in the body that ultimately undergo urine, hair and fingernails, while study for arsenic excretion showed major in the urine (Xu et al., 2012). The human epidemiology studies found the significantly positive correlations between urinary total arsenic concentrations and drinking-water, food and soil concentrations of arsenic Calderon et al., 1999;Halder et al., 2013;Lindberg et al., 2006;Mandal et al., 2004;Ranft et al., 2003). Besides, the half-life of urinary arsenic in the body is about 4 days and urine has a simpler substrate than blood, so urinary arsenic is a biomarker reflecting a person's recent environmental exposure levels (National Research Council Subcommittee on Arsenic in Drinking, 1999). ...
Background
Prenatal exposure to arsenic and mercury have been associated with adverse pregnancy outcomes that might be in part mediated by dynamic modification of imprinting gene that are emerging mechanism.
Objectives
The objective of this study was to examine the impacts of paternal exposure to arsenic and co-exposure to arsenic and mercury on human sperm DNA methylation status of imprinting genes, respectively.
Methods
A total of 352 male subjects (23–52 years old) were recruited and demographic data were obtained through questionnaires. Urinary arsenic and mercury levels were measured using hydride generation-atomic fluorescence spectrometer. Multivariate regression model was employed to investigate the relationship between urinary arsenic levels and sperm DNA methylation status at H19, Meg3 and Peg3, measured by pyrosequencing, and evaluating the interaction with mercury.
Results
After adjusting potential confounds factors by multivariate regression model, the results indicated a significantly positive relationship between urinary arsenic levels and the methylation status of Meg3 at both mean level (β = + 0.125, p < 0.001) and all individual CpGs, i.e., CpG1 (β = + 0.094, p < 0.001), CpG2 (β = + 0.132, p < 0.001), CpG3 (β = + 0.121, p < 0.001), CpG4 (β = + 0.142, p < 0.001), CpG5 (β = + 0.111, p < 0.001), CpG6 (β = + 0.120, p < 0.001), CpG7 (β = + 0.143, p < 0.001), CpG8 (β = + 0.139, p < 0.001) of Meg3 DMRs. The interaction effects analysis indicated the interaction effects of arsenic and mercury on Meg3 were not existing.
Conclusions
Paternal nonoccupational exposure to arsenic induces the altered DNA methylation status of Meg3 in human sperm DNA. In addition, the interaction effects of arsenic and mercury on Meg3 were not existing. These findings would implicate the sensibility of sperm epigenome for environmental pollutions.
... The lack of correlation between total As and As speciation profiles in urine could be explained by the presence of organic As species, such as arsenobetaine (AsB), arsenosugars, and arsenolipids associated with seafood consumption, which may confound the association between total As and As speciation (59). Toenails contain smaller or sometimes undetectable proportions of AsB (60,61) and there is evidence that AsB and other organoarsenicals associated with seafood are efficiently excreted in urine and do not accumulate in the body (62). This suggests that total As in toenails only reflects exposure to iAs (46) which could make them a more viable biospecimen to use in ascertaining the effect of iAs exposure on iAs methylation capacity. ...
Chronic exposure to inorganic arsenic and trace metals has been linked to prostate cancer, and altered arsenic methylation capacity may have an important role in arsenic carcinogenesis. Biomarkers may be able to elucidate this role. Our objectives were to characterize profiles of arsenic species and metallome in toenails and urine samples, compare profiles between prostate cancer cases and controls, and determine the discriminant ability of toenail and urine biomarkers. Toenail samples (n = 576), urine samples (n = 152), and questionnaire data were sourced from the Atlantic Partnership for Tomorrow's Health (PATH) cohort study. Healthy controls were matched to prostate cancer cases (3:1 ratio) on sex, age, smoking status, and the province of residence. Metallome profiles and proportions of arsenic species were measured in toenail and urine samples. Analysis of covariance (ANCOVA) was used to compare the mean percent monomethylarsonic acid (%MMA), dimethylarsonic acid (%DMA), inorganic arsenic (%iAs), primary methylation index (PMI, MMA/iAs), and secondary methylation index (SMI, DMA/MMA). Multivariate analysis of covariance (MANCOVA) was used to compare selected metal concentrations. Mean %MMA was significantly lower and SMI was significantly higher in toenails from prostate cancer cases compared to controls in unadjusted and adjusted models. Proportions of arsenic species were correlated with total arsenic in toenails. Arsenic speciation in urine was not different between cases and controls, nor were metallome profiles in toenails and urine. Our results indicate that toenails are a viable biomarker for altered arsenic speciation in prostate cancer cases and may have greater utility than urine in this context.
... In 1984, the accumulation of methamphetamine and amphetamine in nails was reported from addicted users, indicating that nails can serve as reliable sample for forensic analysis [41]. "Since then, fingernails have proved to be valuable specimens for investigating poisoning caused by heavy metal such as thallium, arsenic and lead" [42][43][44][45][46][47]. "Numerous trace elements were found in considerably higher concentration in nails than in urine or blood" [48][49][50][51]. ...
Forensic toxicology is a field of science that deals with the detection, identification and isolation of drugs, chemicals and other xenobiotics in the biological specimens as well as interpreting the results for medical and other legal investigations. This field encompasses toxicologists and other experts in disciplines such as biochemistry, pharmacology, analytical and clinical chemistry and biology for the purpose of investigating death, drug abuse and poisoning medically and legally. Forensic toxicology has found application majorly in postmortem investigations, human performance, doping control and work place drug testing. Forensic analyses can be broadly divided into two categories: presumptive tests which do not specifically identify the compound present in the sample, but only indicate the type of substance present through signs such as colour change and; confirmatory tests that specifically identifies the substance. Confirmatory tests include chromatography techniques as well as combination of chromatography and mass spectrometry techniques. This article reviews the various biological specimens and analytical techniques used for qualitative and quantitative detection and identification of drugs of abuse, poisons and other xenobiotics and also recommends improvement in the present state of art and evolution of new innovations that can foster global use of forensic toxicology in the nearest future.
... The traditional biomarkers of blood, fingernails, urine and hair have been successfully utilized to determine As toxicity among affected individuals (Huyck et al. 2007;Samanta et al. 2007). Mandal et al. (2004) reported that As levels in urine, fingernails and hair were positively correlated with concentrations of the same in drinking water. Pandey et al. (2007) went on to observe that any one of these biomarkers could be utilized to document exposure to As. Gault et al. (2008) also concluded that As content in hair, nails and drinking water were highly correlated, and that such samples were easy to collect, store and analyse. ...
Open Access from DOI: https://doi.org/10.52905/hbph.v1.7
There is a close association between human biology, epidemiology and public health. Exposure to toxic elements is one area of such associations and global concerns. The Bengal Delta Plain (BDP) is a region where contamination of ground water by arsenic has assumed epidemic proportions. Apart from dermatological manifestations, chronic exposure to arsenic causes a heavy toll through several carcinogenic and non-carcinogenic disorders. This article provides a global overview of groundwater arsenic contamination in the BDP region, especially the sources, speciation, and mobility of arsenic, and critically reviews the effects of arsenic on human health. The present review also provides a summary of comprehensive knowledge on various measures required for mitigation and social consequences of the problem of arsenic contaminated groundwater in the BDP region.
... In the Brazilian territory, the studies carried out during the last two decades have been concentrated mainly in four regions: (i) "Iron Quadrangle" region, Minas Gerais state, in which As is released into the environment through activities related to gold mining Deschamps et al., 2002Deschamps et al., , 2003Borba et al., 2003;Mello et al., 2006;Deschamps and Matschullat, 2007;Bundschuh et al., 2012a;Silva et al., 2018;Carvalho et al., 2018;Paraguassú et al., 2019); (ii) Ribeira Valley region (Paraná, and São Paulo states), which is highly contaminated due to mining, processing and refining of "Pb-Zn-Ag" ores, in which As is naturally found in rocks and soils Abreu and Figueiredo, 2004;Akcil and Koldas, 2006;Blodau, 2006;Campaner and Luiz-Silva, 2009;Cha et al., 2018); (iii) the Amazonia region, including the area of the municipality of Santana, in the state of Amapá (AP), where As is associated with manganese (Mn) ores exploited during the last five decades (Santos et al., 2003;Mandal et al., 2004;J. Bundschuh et al., 2017;de Meyer et al., 2017;da Silva Júnior et al., 2019); and (iv) impact of coastal zone by As-laden river water discharging into the Atlantic Ocean (Mirlean et al., 2011(Mirlean et al., , 2012(Mirlean et al., , 2013(Mirlean et al., , 2014(Mirlean et al., , 2016Cagnin et al., 2017;de Meyer et al., 2017;Dolci et al., 2017;Gao et al., 2018;Baeyens et al., 2019). ...
This review presents a holistic overview of the occurrence, mobilization, and pathways of arsenic (As) from predominantly geogenic sources into different near-surface environmental compartments, together with the respective reported or potential impacts on human health in Latin America. The main sources and pathways of As pollution in this region include: (i) volcanism and geothermalism: (a) volcanic rocks, fluids (e.g., gases) and ash, including large-scale transport of the latter through different mechanisms, (b) geothermal fluids and their exploitation; (ii) natural lixiviation and accelerated mobilization from (mostly sulfidic) metal ore deposits by mining and related activities; (iii) coal deposits and their exploitation; (iv) hydrocarbon reservoirs and co-produced water during exploitation; (v) solute and sediment transport through rivers to the sea; (vi) atmospheric As (dust and aerosol); and (vii) As exposure through geophagy and involuntary ingestion. The two most important and well-recognized sources and mechanisms for As release into the Latin American population's environments are: (i) volcanism and geothermalism, and (ii) strongly accelerated As release from geogenic sources by mining and related activities. Several new analyses from As-endemic areas of Latin America emphasize that As-related mortality and morbidity continue to rise even after decadal efforts towards lowering As exposure. Several public health regulatory institutions have classified As and its compounds as carcinogenic chemicals, as As uptake can affect several organ systems, viz. dermal, gastrointestinal, peptic, neurological, respiratory, reproductive, following exposure. Accordingly, ingesting large amounts of As can damage the stomach, kidneys, liver, heart, and nervous system; and, in severe cases, may cause death. Moreover, breathing air with high As levels can cause lung damage, shortness of breath, chest pain, and cough. Further, As compounds, being corrosive, can also cause skin lesions or damage eyes, and long-term exposure to As can lead to cancer development in several organs.
... iii. The Amazon region (Figure 1, BR4-13), including the area of the Municipality of Santana, in the State of Amap a, where As is associated with manganese (Mn) ores exploited during the last five decades (Santos et al., 2003;Mandal et al., 2004;Bundschuh et al., 2017, de Meyer et al., 2017, da Silva Junior et al., 2019. iv. ...
Today (year 2020), the globally recognized problem of arsenic (As) contamination of water resources and other environments at toxic levels has been reported in all of the 20 Latin American countries. The present review indicates that As is prevalent in 200 areas across these countries. Arsenic is naturally released into the environment and mobilized from geogenic sources comprising: (i) volcanic rocks and emissions, the latter being transported over thousands of kilometers from the source, (ii) metallic mineral deposits, which get exposed to human beings and livestock through drinking water or food chain, and (iii) As-rich geothermal fluids ascending from deep geothermal reservoirs contaminate freshwater sources. The challenge for mitigation is increased manifold by mining and related activities, as As from mining sites is transported by rivers over long distances and even reaches and contaminates coastal environments. The recognition of the As problem by the authorities in several countries has led to various actions for remediation, but there is a lack of long-term strategies for such interventions. Often only total As concentration is reported, while data on As sources, mobilization, speciation, mobility and pathways are lacking which is imperative for assessing quality of any water source, i.e. public and private.
... It was found that inorganic arsenic is suggested to be more toxic than organic forms in terms of human health [15]. Most cases of arsenic-induced toxicity in humans are due to natural exposure to inorganic arsenic via air, water, soil, dust and food [16,17]. In the last centuries, the use of arsenical compounds was increased, namely: in pigments, dyes, preservatives of animal hides, glass manufacture, agricultural pesticides, and various pharmaceutical substances [18]. ...
The use of unconventional biological materials as biomarkers in trace element studies has increased in terms of published research studies. In the present study, human scalp hair samples (n ¼ 65) were used to be a possible biomarker for the arsenic level in the human body as no study has been published in Karbala city, Iraq yet. The level of arsenic was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The validity, precision and accuracy of the methodology were evaluated using a "pooled" sample and certified reference materials, respectively. The validation methods provided acceptable levels of precision and accuracy with lower range of RSD (1.1%) and acceptable range of elemental recovery (97.72%), respectively. The influence of various factors including health status, gender, smoking activity, interaction, individual's age and drinking water on arsenic levels in washed scalp hair was investigated using the analysis of covariance (ANCOVA), analysis of variance (ANOVA), F-test and a two-tailed pooled t-test. The arsenic levels in washed scalp hair of breast cancer patients (8.270 ± 4.345 mg/km) were significantly increased when compared with healthy individuals (6.266 ± 1.892 mg/km) (p < 0.05). It was found that the levels of As were significantly higher in washed scalp hair of males (12.395 ± 6.243 mg/kg) than those for females (7.637 ± 4.234 mg/kg) (P < 0.05). Hair of smokers (16.078 ± 4.245 mg/kg) was significantly contained more As than hair of non-smokers (6.532 ± 2.817 mg/kg). The levels of As in the age group (over 40 year) are significantly different when compared with the two remaining groups (under 20 year, and 20e40 year). The value of correlation coefficient (r ¼ 0.907, p < 0.001) was indicated that there is significant positive correlation between the arsenic level in the scalp hair and the arsenic level in the drinking water.
... Di samping itu, manusia boleh terdedah kepada logam berat arsenik melalui kedua-dua sumber antropogenik dan semula jadi (Colin & Micheal 2005). Kebanyakan kes keracunan akibat-arsenik dalam manusia adalah disebabkan oleh pendedahan semulajadi kepada arsenik bukan organik melalui udara, air (Jarup 2013), tanah, habuk dan makanan dan alam sekitar (Brima et al. 2006;Mandal et al. 2004). Meacher et al. (2002) dalam kajiannya menyatakan bahawa air minuman merupakan punca pendedahan manusia kepada logam berat arsenik bukan organik. ...
... The high As level at site AOB confirms earlier report that contaminated soils such as tailings were potential source of As exposure (Liu et al. 2005;Somerset et al. 2005;WHO 2001). Chronic exposure to arsenic results in unusual patterns of skin hyperpigmentation, peripheral nerve damage manifesting as numbness, weakness, and blood vessel damage resulting in a gangrenous condition affecting the extremities (Mandal et al. 2004;Ç öl et al. 1999). Similar high levels of As, Cu, Pb and Zn were reported by earlier researchers around Obuasi mining areas (AOB) of Ghana (Antwi-Agyei et al. 2009;Amonoo-Neizer et al. 1995;Asiam 1996;Smedley 1996;Smedley et al. 1996;Ahmad and Carboo 2000;Kumi-Boateng 2007). ...
Analysis of soil samples around pristine and major gold-mining areas in Ghana was carried out for heavy metals as part of a larger soil contamination and metal background study. The surface soil samples were digested using microwave digester (aqua regia) and analyzed with ICP-MS for As, Cd, Hg, Zn, Co, Cu, Mn, Fe, Al, V, Cr, and Pb. The average concentrations (mg/L) for the metals ranged from 0.01 ± 0.01 (Cd) to 86,859.36 ± 47.07 (Fe) for the pristine sites, and 0.01 ± 0.01 (Cd) to 59,006.95 ± 79.06 (Fe) for the mining sites. Mercury was below the detection limit of the analytical instrument (0.029). The concentrations of heavy metals from this study were used to assess their contamination levels, and health risks. The results showed that, the metals ranked by severity of health risks as As > Pb > Cr > Cd. Principal component analysis (PCA) and cluster analysis showed two groupings with the PCA showing metals variability explained by 79.02%. Results from the PCA and Cluster analysis indicate anthropogenic sources of the metals which may be emanating from gold-mining activities. Results from multi-criteria ranking and pattern recognition employing PROMETHEE and GAIA revealed major contribution of the metals from the mining sites with metal variability explained by 72.83%. This is the first time a multi-criteria approach is employed to characterize heavy metal contamination in Ghana, and the study nevertheless brought to light the impact of mining on human health and the environment with implications for other mineral areas around the globe.
... Furthermore, the studies considering various urinary arsenic profiles as an internal dose and exploring the effects of these metabolites on AD risk were scarce. Urinary and blood levels of As reflected the short-term and ongoing exposures, respectively; furthermore, blood As was not used to reflect the level of As metabolism (Mandal et al., 2004). Therefore, in the present study, we used the urinary As levels as the individual exposure to reflect the As metabolism capability. ...
... It was found that inorganic arsenic is suggested to be more toxic than organic forms in terms of human health 10 . Most cases of arsenicinduced toxicity in humans are due to natural exposure to inorganic arsenic via air, water, soil, dust and food 11,12 . In recent decades many studies have reported that arsenic plays a significant role in a number of diseases, such as cancer and diabetes 13,7 . ...
The use of unconventional biological materials as biomarkers in trace element studies has increased in terms of published research studies. In this study, human scalp hair and fingernails were used to be a possible biomarker for arsenic in the human body as no study has been published in Karbala yet. Samples were obtained from 56 healthy individuals resident in Karbala, Iraq. The level of arsenic was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The validity, precision and accuracy of the methodology were evaluated using a “pooled” sample for each media and certified reference materials. The validation methods provided acceptable levels of precision and accuracy with lower range of RSD (1.1%) and acceptable range of elemental recoveries (98.09 %), respectively. The results show that the arsenic levels of study sample are in general agreement with the literature ranges for scalp hair with exception reported for fingernails. It was found that there was no significant difference for arsenic between the two tissues (at P < 0.05). In addition, the value of correlation coefficient (r = 0.804, P = 0.05) was indicated that there is a significant positive correlations for arsenic level between scalp hair and fingernails.
(PDF) Determination of Arsenic in Human Scalp Hair and Fingernails of Healthy Individuals Resident in Karbala, Iraq by Using ICP-OES. Available from: https://www.researchgate.net/publication/322569055_Determination_of_Arsenic_in_Human_Scalp_Hair_and_Fingernails_of_Healthy_Individuals_Resident_in_Karbala_Iraq_by_Using_ICP-OES [accessed Jan 01 2021].
... HPLC technique is the most successful separation technique applied in arsenic speciation analysis. IC-ICP MS method has frequently been used for As speciation in various biological materials [64,65]. Arsenobetaine (AsB), inorganic arsenite (As III ), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), inorganic arsenate (As V ), 3-nitro-4hydroxyphenylarsonic acid (Roxarsone) and N-acetyl-4-hydroxy-m-arsanilic acid were identified in breast muscle tissues [66]. ...
... HPLC technique is the most successful separation technique applied in arsenic speciation analysis. IC-ICP MS method has frequently been used for As speciation in various biological materials [64,65]. Arsenobetaine (AsB), inorganic arsenite (As III ), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), inorganic arsenate (As V ), 3-nitro-4- hydroxyphenylarsonic acid (Roxarsone) and N-acetyl-4-hydroxy-m-arsanilic acid were identified in breast muscle tissues [66]. ...
... The biological impact of metals (Cr, As, Fe, Mn, etc.) can be completely changed by their oxidation states, their association with specific ligands, and their concentration in solution (Leonard and Lauwerys, 1980;Thomas et al., 2001). For instance, it is commonly stated that the toxicity from arsenic exposure varies in the order As 3þ > As 5þ > Asmethylated species (Hirano et al., 2004;Mandal et al., 2004;Repetto et al., 1994;Vahidnia et al., 2008). Similarly, it is well known that Cr 3þ is an essential micronutrient playing a role in glucose metabolism (Anderson, 1997;Zafra-Stone et al., 2007) whereas Cr 6þ is carcinogen and induces acute and chronic toxic effects (Manerikar et al., 2008;Wise et al., 2006). ...
The level of production of nanoparticles will inevitably lead to their appearance in air, water, soils, and organisms. A theoretical framework that relates properties of nanoparticles to their biological effects is needed to identify possible risks to human health and the environment. This paper considers the properties of dispersed metallic nanoparticles and highlights the relationship between the chemical stability of these nanoparticles and their in vitro toxicity. Analysis of published data suggests that chemically stable metallic nanoparticles have no significant cellular toxicity, whereas nanoparticles able to be oxidized, reduced or dissolved are cytotoxic and even genotoxic for cellular organisms.
... The elements found to be significant are As, Be, Bi, Cd, Cu, Cr, Ni, Pb, and Zn in smelting areas and Be, Cd, Co, Cu, Cr, Ni, and Zn. Urinary As concentrations in both the smelting (0.40 μg L −1 ) and mining (0.53 μg L −1 ) areas were not high compared with a control population (8.6 μg L −1 , Mandal et al. 2004). As levels in hair were 0.23 μg g −1 in the smelting areas and 0.40 μg g −1 in the mining area, compared with a lower 0.07 μg g −1 in a control population ). ...
Mining and smelting areas in Hezhang have generated a large amount of heavy metals into the environment. For that cause, an evaluative study on human exposure to heavy metals including Co, Ni, Cu, Zn, Cr, As, Cd, Pb, Sb, Bi, Be, and Hg in hair and urine was conducted for their concentrations and correlations. Daily exposure and non-carcinogenic and carcinogenic risk were estimated. Sixty-eight scalp hair and 66 urine samples were taken from participants of different ages (6–17, 18–40, 41–60, and ≥ 65 years) living in the vicinity of an agricultural soil near mine and smelting areas. The results compared to the earlier studies showed an elevated concentration of Pb, Be, Bi, Co, Cr, Ni, Sb, and Zn in hair and urine. These heavy metals were more elevated in mining than in smelting. Considering gender differences, females were likely to be more affected than male. By investigating age differences in this area, high heavy metal concentrations in male’s hair and urine existed in age of 18–40 and ≥ 66, respectively. However, females did not present homogeneous age distribution. Hair and urine showed a different distribution of heavy metals in different age and gender. In some cases, significant correlation was found between heavy metals in hair and urine (P > 0.05 and P > 0.01) in mining area. The estimated average daily intake of heavy metals in vegetables showed a great contribution compared to the soil and water. Non-carcinogenic and carcinogenic risk values of total pathways in mining and smelting areas were higher than 1 and exceeded the acceptable levels. Thus, the obtained data might be useful for further studies. They can serve as a basis of comparison and assessing the effect of simultaneous exposure from heavy metals in mining and smelting areas, and potential health risks from exposure to heavy metals in vegetables need more consideration.
... Approximately 70% of organic and inorganic arsenic is excreted through the kidney via urine 7 , and a small portion is excreted through the skin, hair, nails, and faeces 18 . Therefore, urinary arsenic speciation profiles are crucial for investigating the metabolism, toxicity, and transformation of ingested arsenic 19,20 , and they can be used as effective biomarkers for internal dosing 3 . By contrast, total arsenic in blood is an imprecise biomarker of exposure because of the relative toxicity and methylation efficiency of the different arsenic forms and the short-term effect of the exposure measure compared with total lead in blood 21 . ...
This case–control study identified the association between the arsenic methylation capacity and developmental delays and explored the association of this capacity with the health status of children. We recruited 120 children with developmental delays and 120 age- and sex-matched children without developmental delays. The health status of the children was assessed using the Pediatric Quality of Life Inventory (PedsQL) and Pediatric Outcomes Data Collection Instrument (PODCI). The arsenic methylation capacity was determined by the percentages of inorganic arsenic (InAs%), monomethylarsonic acid (MMAV%), and dimethylarsinic acid (DMAV%) through liquid chromatography and hydride generation atomic absorption spectrometry. Developmental delays were significantly positively associated with the total urinary arsenic concentration, InAs%, and MMAV%, and was significantly negatively associated with DMAV% in a dose-dependent manner. MMAV% was negatively associated with the health-related quality of life (HRQOL; −1.19 to −1.46, P < 0.01) and functional performance (−0.82 to −1.14, P < 0.01), whereas DMAV% was positively associated with HRQOL (0.33–0.35, P < 0.05) and functional performance (0.21–0.39, P < 0.01–0.05) in all children and in those with developmental delays. The arsenic methylation capacity is dose-dependently associated with developmental delays and with the health status of children, particularly those with developmental delays.
... AB was detected in the RBCs of healthy male volunteers [33]. AB and dimethylarsenical were detected in the RBCs of humans who stopped drinking As-contaminated water two and five years before blood collection [34,35]. ...
Less information is available on the metabolism of organic arsenicals compared to inorganic arsenic in mammals. In the present study, we investigated tissue distribution, metabolism and excretion in rats of organoarsenicals, dimethylarsinic acid (DMAV), arsenobetaine (AB), arsenocholine (AC) and trimethylarsine oxide (TMAOV). Among these animals, arsenic concentrations in red blood cells (RBCs) and spleen increased remarkably only in the DMAV group. Hepatic arsenic concentration increased significantly only in the AC group. Approximately 17%, 72% and 60% of the dose was excreted in urine in two days in the DMAV, AB and AC groups, respectively; virtually the entire dose was excreted in urine in one day in the TMAOV group. On the other hand, approximately 18%, 0.2%, 0.5% and 0.1% of the dose was excreted in feces in two days in the DMAV, AB, AC and TMAOV groups, respectively. A large amount of arsenic was accumulated in RBCs in the form of protein-bound dimethylarsinous acid (DMAIII), and dimethylmonothioarsinic acid (DMMTAV), a reportedly toxic thio-arsenical, was found in urine and fecal extract in the DMAV group. These results suggest that intake of DMAV is a potential health hazard, given that the metabolites of DMAV, such as DMAIII and DMMTAV, are known to be highly toxic.
... It was found that inorganic arsenic is suggested to be more toxic than organic forms in terms of human health [15]. Most cases of arsenic-induced toxicity in humans are due to natural exposure to inorganic arsenic via air, water, soil, dust and food [16,17]. In the last centuries, the use of arsenical compounds was increased, namely: in pigments, dyes, preservatives of animal hides, glass manufacture, agricultural pesticides, and various pharmaceutical substances [18]. ...
In this study, strontium levels in biological (human teeth and fingernails) samples collected from Iraqi individual residents in Karbala city, Iraq were determined by using inductively coupled plasma optical emission spectrometry. The determination of strontium was undertaken for human teeth (2.613 ± 0.450 mg/Kg) and fingernail samples (2.184 ± 0.636 mg/Kg). Significantly higher fingernail levels of strontium were found in carious patients (2.599 ± 0.234 mg/Kg) when compared with healthy individuals (1.363 ± 0.246 mg/Kg) at a probability level, p < 0.05. The influence of various factors including gender, smoking activity, health status, individual's age and drinking water on strontium levels was determined using a two tailed t-test. Significantly higher fingernail levels of strontium were found in carious patients and smokers when compared with healthy individuals and non-smokers, respectively at a probability level, p < 0.05. On the other hand, no significant effects were found for gender, smoking activity and age on the strontium levels in the human teeth carious samples. Similar results were also reported for fingernail samples in terms of the effect of gender and age. A strongly positive significant correlation was seen between fingernails strontium and drinking water strontium (r = 0.894, p < 0.05). In contrast, there is not any significant correlation between the level of strontium in teeth and washed fingernails (r = 0.195, p < 0.05).
... Those that do are limited by being restricted to a very small number of individuals (Lai et al., 2004;Hulle et al., 2004), or are based on epidemiological data on populations from different countries (Loffredo et al., 2003) and/or involve the study of exposed populations (Hopenhayn-Rich et al., 1996). Despite these drawbacks, our understanding of arsenic metabolism pathway is progressing thanks to studies investigating speciation of arsenicals in biological samples (Mandal et al., 2004;Steinmaus et al., 2005;Suzuki, 2005). ...
... It was found that inorganic arsenic is suggested to be more toxic than organic forms in terms of human health [15]. Most cases of arsenic-induced toxicity in humans are due to natural exposure to inorganic arsenic via air, water, soil, dust and food [16,17]. In the last centuries, the use of arsenical compounds was increased, namely: in pigments, dyes, preservatives of animal hides, glass manufacture, agricultural pesticides, and various pharmaceutical substances [18]. ...
The use of unconventional biological materials as biomarkers in trace element studies has increased in terms of published research studies. In the present study, human scalp hair samples (n = 65) were used to be a possible biomarker for the arsenic level in the human body as no study has been published in Karbala city, Iraq yet. The level of arsenic was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The validity, precision and accuracy of the methodology were evaluated using a “pooled” sample and certified reference materials, respectively. The validation methods provided acceptable levels of precision and accuracy with lower range of RSD (1.1%) and acceptable range of elemental recovery (97.72%), respectively. The influence of various factors including health status, gender, smoking activity, interaction, individual's age and drinking water on arsenic levels in washed scalp hair was investigated using the analysis of covariance (ANCOVA), analysis of variance (ANOVA), F-test and a two-tailed pooled t-test. The arsenic levels in washed scalp hair of breast cancer patients (8.270 ± 4.345 mg/km) were significantly increased when compared with healthy individuals (6.266 ± 1.892 mg/km) (p < 0.05). It was found that the levels of As were significantly higher in washed scalp hair of males (12.395 ± 6.243 mg/kg) than those for females (7.637 ± 4.234 mg/kg) (P < 0.05). Hair of smokers (16.078 ± 4.245 mg/kg) was significantly contained more As than hair of non-smokers (6.532 ± 2.817 mg/kg). The levels of As in the age group (over 40 year) are significantly different when compared with the two remaining groups (under 20 year, and 20–40 year). The value of correlation coefficient (r = 0.907, p < 0.001) was indicated that there is significant positive correlation between the arsenic level in the scalp hair and the arsenic level in the drinking water.
Hair analysis is a reliable and widely used tool to evaluate drug exposure in many fields, including workplace testing, drug abuse history and withdrawal control, post-mortem toxicology, doping control, therapeutic drug monitoring of pharmaceuticals and even environmental exposure to toxic agents. Compounds incorporated into the hair structure resist hair growth and regular washing for several months, leading to a potential chronological trace of exposure, with farther periods corresponding to the hair segments more distant from the hair root. The relentless improvement of analytical procedures and instrumental technologies, together with the continuous introduction of new psychoactive substances, have led to an increasing number of studies and practical applications of hair analysis.
This book is a comprehensive guide to hair analysis from general concepts, ideal for students and those new to the field, to interpretation and advanced methods for experts working in the area. With contributions from world-leading scientists in each field, this book describes state-of-the-art, emerging issues and recent analytical approaches to hair analysis that will serve as an essential tool to clinical and forensic toxicology laboratories across the globe.
Introduction
Chronic exposure to arsenic through drinking water has been linked to several cancers. The metabolism of arsenic is thought to play a key role in arsenic-related carcinogenesis as metabolites of varying toxicity are produced and either stored in or excreted from the body. Atlantic Canada has the highest age-standardized incidence rates of all cancers in the country. This may be due to its high levels of environmental arsenic and the prevalence of unregulated private wells for water consumption. Here, we aimed to characterize the profiles of arsenic species and metallome in the toenails of four cancer groups, compare them to healthy participants (N = 338), and assess potential associations between the profiles with cancer prevalence.
Methods
This study employed a case–control design. Toenail samples and questionnaire data from cases (breast, cervical, prostate, and skin cancers) and controls were sourced from the Atlantic Partnership for Tomorrow’s Health (PATH) cohort study. The levels of arsenic species were measured using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) paired with High Performance Liquid Chromatography (HPLC) and total concentrations of metallome (23 metals) were determined by ICP-MS separately. Multivariate analyses were conducted to compare cases with controls within each cancer group.
Results
Arsenic speciation profiles varied by cancer type and were significantly different between cases and controls in the breast (p = 0.0330), cervical (p = 0.0228), and skin (p = 0.0228) cancer groups. In addition, the profiles of metallome (nine metals) were significantly differentiated in the prostate (p = 0.0244) and skin (p = 0.0321) cancer groups, with higher zinc concentrations among cases compared to controls.
Conclusion
History of cancer diagnosis was associated with specific profiles of arsenic species and metallome. Our results indicate that arsenic methylation and zinc levels, as measured in toenails, may be an important biomarker for cancer prevalence. Further research is needed to use toenails as a prognostic measure of arsenic-and other metal-induced cancer.
Urine samples were collected from 75 subjects in the Lagunera area of Mexico. There were four groups, based on total arsenic concentrations in their drinking water (9-100μg/L). After collection, the samples were immediately put in a portable icebox containing dry ice, and they were kept frozen while being transported to the University of Arizona, Tucson where they were stored at-70°C before analysis. Arsenic metabolites, including MMA(III) and DMA(III), were measured in urine samples by using HPLC-ICP-MS. The average percentage of MMA(III) in urine samples of arsenic exposed people in the Lagunera area of Mexico were 0.44%, 0.26%, N.D. (Not Detectable), and 0.20% of total arsenic for the groups 4, 1, 3, and 2 where arsenic concentrations in their drinking water were 9, 17.5, 52, and 100 (µg/L), respectively. This small percentage of MMA(III) were detected only in 14 urine samples (~18%) out of total 75 samples. DMA(III) was not measured in any of these urine samples (n=75) but measured DMA(V) in all samples. The highest percentage of arsenic metabolites was DMA(V) (61% to 74%) of the total arsenic in urine. It indicates that most of the MMA(III) methylated to DMA(V) in tissues, but less percentage or most of the DMA(V) may be reduced to DMA(III) and due to its instability, it could be immediately oxidized to DMA(V) in tissues again or in urine after collection. These findings suggest that the +5-oxidation state of arsenic metabolite, DMA(V), could be the most dominant methylated arsenic metabolite in humans' urine of arsenic exposed population. In animal tissues, the +3-oxidation state of arsenic metabolites, MMA(III) and DMA(III), were measured in mice tissues after administering a single intra-muscular dose of sodium arsenate (4.16 mg As/kg body weight). Liver, kidneys, urinary bladder tissue, lungs, testes, and heart were removed at the following times, 0, 0.5, 1, 2, 4, 8, and 12 h. The tissues were homogenized at 4°C (cold room), and the homogenized samples were extracted immediately. After extraction, I measured the arsenic species as soon as possible by using HPLC-ICP-MS (Chowdhury, et al., 2006). The concentration of the very toxic MMA(III) was significantly higher than that of MMA(V) in all of the tissues tested (Liver, kidneys, urinary bladder tissue, lungs, testes, and heart). At 2 h, after injection, the highest concentration of MMA(III) was in the kidneys. Compared with the other species of arsenic, MMA(V) concentrations were the lowest in all tissues examined. On the other hand, the concentration of DMA(V) was higher than DMA(III) in the liver, kidneys, urinary bladder tissue, lungs, and testes at all times. DMA(V) accumulated at a higher concentration in the urinary bladder tissue and lungs, but the concentration of DMA(III) was the highest in the urinary bladder tissue, followed by the kidneys, lungs, heart, testes, and liver. In all of the tissues, both DMA(V) and DMA(III) were highest at 4 2 h for the WT (wildtype) mice. The concentration of DMA(III) was significantly higher in the urinary bladder tissue than in other tissues (p<0.05), except in the kidneys of the mice. The results indicate that MMA(V) reduced to MMA(III) faster, comparing to DMA(V) to DMA(III). It could be that most of the MMA(V) reduced to MMA(III) and methylated to DMA(V), but less/most of the MMA(III) converted to DMA(V)↔ DMA(III), but DMA(III) may be very instable and oxidized to DMA(V) very quickly. This might have been because the DMA(III) would be more instable in the tissues, comparing to MMA(III), and oxidized faster, compared to MMA(III). Also, it could be suitable for the bonding of MMA(III) to tissue components or proteins, compared to DMA(III). These results also indicate that due to the instability and faster oxidation of DMA(III), there was no detectable level of DMA(III), but low level of MMA(III) was measured in some urine samples due to its more stability and bonding capacity with proteins, compared to DMA(III). Both MMA(III) and DMA(III) were detected in tissues but not in urines, and these reports have suggested that tissue levels of MMA(III) and DMA(III) are both more relevant and less susceptible to oxidative artifacts than urine samples. In conclusion, the distribution of arsenic metabolites in urine was supported with the distribution of these species in mouse tissues. The trivalent MMA(III) compound could be the most dominant, very toxic arsenic metabolite in humans' tissues for a short period of time (e.g., MMA(III) was highest at 2 h in mouse tissues after injection of sodium arsenate) but not in urine because it methylated to DMA(V) in tissues, and some percentage of MMA(III) could also be oxidized to MMA(V) again. On the other hand, DMA(V), instead of DMA(III), would be another dominant arsenic metabolite in tissues as well as in urine because we found the final metabolites of arsenic in urine where most of the arsenic metabolite was DMA(V). The stability/instability of MMA(III) and DMA(III) may depend on biological environment, genetic variability, and other factors. However, more experiments are needed to understand the mechanism of inorganic arsenic biotransformation and stability or instability of highly toxic arsenic metabolites, MMA(III) and DMA(III).. 2023 Sciforce Publications. All rights reserved.
Within the past two decades, there have been many studies for quantitative analysis on human hair samples. Microscopical and chemical analysis techniques have been used to analyze various aspects of hair regarding biological, chemical, anthropological, cosmetic, and forensic applications. Studies have attempted to develop quantification methods to increase the evidentiary value of hair in forensic casework. The literature reviewed in this paper provides some of the current techniques used for forensic examinations and quantitative methods. Although microscopical analysis has been scrutinized in the past, using chemical and microscopical techniques can provide a myriad of information. The extraction of DNA from hair provides high-value evidence; however, it may not be readily available and may yield inconclusive results. Hair analysis can be used for many forensic applications such as comparison, toxicology, and exposure analysis. In this article, we will review published research material regarding chemical and microscopical techniques for human hair analysis. Aspects considered for this review were the sample size requirement for analysis and the destructive nature of the instrumental method. This review will focus on both macro and micro quantitative methods for human hair analysis.
Long term exposure to arsenic through consumption of contaminated groundwater has been a global issue since the last five decades; while from an alternate standpoint, arsenic compounds have emerged as unparallel chemotherapeutic drugs. This review highlights the contribution from arsenic speciation studies that have played a pivotal role in the progression of our understanding of the biological behaviour of arsenic in humans. We also discuss the limitations of the speciation studies and their association with the interpretation of arsenic metabolism. Chromatographic separation followed by spectroscopic detection as well as the utilization of biotinylated pull-down assays, protein microarray and radiolabelled arsenic have been instrumental in identifying hundreds of metabolic arsenic conjugates, while, computational modelling has predicted thousands of them. However, these species exhibit a variegated pattern, which supports more than one hypothesis for the metabolic pathway of arsenic. Thus, the arsenic species are yet to be integrated into a coherent mechanistic pathway depicting its chemicobiological fate. Novel biorelevant arsenic species have been identified due to significant evolution in experimental methodologies. However, these methods are specific for the identification of only a group of arsenicals sharing similar physiochemical properties; and may not be applicable to other constituents of the vast spectrum of arsenic species. Consequently, the identity of arsenic binding partners in vivo and the sequence of events in arsenic metabolism are still elusive. This resonates the need for additional focus on the extraction and characterization of both low and high molecular weight arsenicals in a combinative manner.
Arsenic speciation analysis was conducted on in oil and in brine canned solid tuna samples using ionic chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS). First, the method was optimized and validated. The extraction of water-soluble arsenic species (arsenobetaine (AsB), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), As (III), and As (V)) was performed with (NH4)2CO3 at pH 10.5. The presence of the sample matrix showed no effect on the selectivity of the method by a t-test (p<0.05) and an external calibration method was applied. The limits of quantification for the five arsenic species were 0.59 mg kg⁻¹ (AsB), 0.10 mg kg⁻¹ (DMA), 0.12 mg kg⁻¹ (As (III)), 0.07 mg kg⁻¹ (MMA) and 0.10 mg kg⁻¹ (As (V)). Method accuracy was tested through the analysis of the reference material BCR-627 (tuna fish muscle tissue) and a good agreement was obtained. Total arsenic in the solid canned tuna ranged from 2.65-5.81 mg kg⁻¹ in-oil samples and from 2.74-5.70 mg kg⁻¹ in the in-brine samples, levels higher than the limits established by the Brazilian sanitary standards. However, the speciation showed that the major species is the non-toxic arsenobetaine.
Arsenic in the environment occurs in both organic and inorganic compounds in their trivalent or pentavalent state. Certain fish and crustaceans contain very high levels of organic arsenic, often as arsenobetaine. In most other foodstuffs, levels of arsenic are low and the form is not known. The total daily intake of arsenic in the general population is reported to be approximately a few tenths of a milligram but varies to a great extent depending on the amount of fish consumed.
Both organic arsenic in seafood and inorganic arsenic in water, beverages, and drugs have been shown to be readily absorbed (70%–90%) by the gastrointestinal tract. Some reports also indicate a fairly high degree of absorption after the inhalation of arsenic.
Absorbed arsenic, irrespective of the form, is widely distributed in the body. After exposure to inorganic arsenic, clearance of arsenic from the skin, upper gastrointestinal tract, epididymis, thyroid, and skeleton is slower than from other organs. The highest levels of arsenic in humans are normally found in the hair, nails, and skin. The main route of excretion is through the kidneys. After ingestion of arsenite or arsenate, approximately 35% of the dose is excreted within 2 days. From animal experiments, it seems that insoluble inorganic arsenic inhaled through the airway is deposited and retained in lung tissue for a relatively long time. Animal data indicate arsenobetaine accumulation in cartilage, testes, epididymis, and muscle. Of ingested arsenobetaine, 50%–80% is excreted in the urine within 2 days.
Biotransformation of inorganic arsenic has been shown to occur in both animals and humans. Methylated compounds, such as methylarsonic acid and dimethylarsinic acid, have been detected in the urine after ingestion or inhalation of inorganic arsenic. Reduction of arsenate and oxidation of arsenite in vivo has been demonstrated in experimental animals. Recently, a human arsenic methyltransferase has been identified.
Medications, contaminated food, beverages, and drinking water have given rise to a number of episodes of arsenic poisoning.
Inorganic arsenic-induced skin lesions such as dermatoses, which may include eruption, pigmentation, or leukodermal hyperkeratosis, may ultimately lead to the development of skin cancer and Bowen disease. Effects on the nervous system (e.g., peripheral nervous disturbance), as well as on the heart and circulatory system (e.g., abnormal electrocardiograms, peripheral vascular disturbances with gangrene of the extremities, ischemic heart disease, cerebral infarction, and erectile dysfunction), have also been reported after chronic exposure to inorganic arsenic. Hematological changes after inorganic arsenic exposure are characterized by anemia and leukopenia. Chronic oral ingestion of inorganic arsenic in drinking water has also been reported to cause internal cancers (of the lung, bladder, kidney, and liver), diabetes, hypertension, cataract, pterygium, and developmental retardation.
Arsenic poisoning among industrial workers is characterized by perforation of the nasal septum, skin changes, and peripheral neuritis. There is substantial epidemiological evidence of an excessive risk of lung cancer among workers exposed to arsenic.
Arsine gas is a powerful hemolytic poison encountered under some industrial conditions. Arsine poisoning is characterized by nausea, vomiting, headache, shortness of breath, and hemoglobinuria.
The toxic metalloid inorganic arsenic (iAs) is widely distributed in the environment. Chronic exposure to iAs from environmental sources has been linked to a variety of human diseases. Methylation of iAs is the primary pathway for metabolism of iAs. In humans, methylation of iAs is catalyzed by arsenic (+ 3 oxidation state) methyltransferase (AS3MT). Conversion of iAs to mono- and di-methylated species (MAs and DMAs) detoxifies iAs by increasing the rate of whole body clearance of arsenic. Interindividual differences in iAs metabolism play key roles in pathogenesis of and susceptibility to a range of disease outcomes associated with iAs exposure. These adverse health effects are in part associated with the production of methylated trivalent arsenic species, methylarsonous acid (MAsIII) and dimethylarsinous acid (DMAsIII), during AS3MT-catalyzed methylation of iAs. The formation of these metabolites activates iAs to unique forms that cause disease initiation and progression. Taken together, the current evidence suggests that methylation of iAs is a pathway for detoxification and for activation of the metalloid. Beyond this general understanding of the consequences of iAs methylation, many questions remain unanswered. Our knowledge of metabolic targets for MAsIII and DMAsIII in human cells and mechanisms for interactions between these arsenicals and targets is incomplete. Development of novel analytical methods for quantitation of MAsIII and DMAsIII in biological samples promises to address some of these gaps. Here, we summarize current knowledge of the enzymatic basis of MAsIII and DMAsIII formation, the toxic actions of these metabolites, and methods available for their detection and quantification in biomatrices. Major knowledge gaps and future research directions are also discussed.
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This volume, closely related to MILS-6, deals mainly with metal(loid)-alkyl derivatives but also with the rarer aryl compounds. Most of these (commonly toxic) compounds are formed in the environment by microorganisms, but some anthropogenic input occurs as well. MILS-7, providing a most up-to-date view, is of special relevance for researchers in analytical and bioinorganic chemistry, enzymology, environmental chemistry, physiology, toxicology, and related medical fields.
Arsenicosis leads to various irreversible damages in several organs and is considered to be a carcinogen. The effects of chronic arsenic poisoning are a result of an imbalance between pro- and antioxidant homeostasis, oxidative stress, as well as DNA and protein damage. Curcumin, the polyphenolic pigment extracted from the rhizome of Curcuma longa, is well-known for its pleiotropic medicinal effects. Curcumin has been shown to have ameliorative effects in arsenic-induced genotoxicity, nephrotoxicity, hepatotoxicity, angiogenesis, skin diseases, reproductive toxicity, neurotoxicity, and immunotoxicity. This review aims to summarize the scientific evidence on arsenic toxicity in various organs and the ameliorative effects of curcumin on the arsenic toxicity.
Trace elements are present at low concentrations in biological samples and many of the analytes that need to be measured occur naturally not only in such specimens, but also in the environment. This chapter provides information on the sample requirements for measurements of metals/trace elements. The aims of sample preparation are to transform the specimen into a suitable form for introduction to the analytical instrument, with the analytes at concentrations that will produce a measurable response, and to reduce or eliminate possible interferences. The chapter describes the general principles of optical emission spectroscopy, atomic absorption spectrometry, atomic emission and atomic fluorescence spectrometry, inductively coupled plasma‐mass spectrometry, and X‐ray fluorescence. It discusses the applications of colorimetry, fluorimetry, electrochemical methods, and chromatographic methods in the detection of trace elements and toxic metals.
Setting regulatory limits for arsenic in food is complicated owing to the enormous diversity of arsenic metabolism in humans, lack of knowledge about the toxicity of these chemicals, and lack of accurate arsenic speciation data on foodstuffs. Identification and quantification of the toxic arsenic compounds is imperative to understanding the risk associated with exposure to arsenic from dietary intake, which in turn underscores the need for speciation analysis of the food. Arsenic speciation in seafood is challenging owing to its existence in myriads of chemical forms and oxidation states. Interconversions occurring between chemical forms, matrix complexity, lack of standards and certified reference materials, and lack of widely accepted measurement protocols present additional challenges. This review covers the current analytical techniques for diverse arsenic species. The requirement for high quality arsenic speciation data that is essential for establishing legislation and setting regulatory limits for arsenic in food is explored.
Antimony (Sb) is a useful metalloid in many industries and a therapeutic agent for leishmaniasis in developing countries. Thus, it is expected that humans and wild animals face the risk of exposure to Sb. Although Sb is generally recognized as a toxic element, the mechanisms underlying its toxicity have not been fully elucidated yet. The objective of this study was to evaluate species differences in Sb distribution in blood and urine between rat and hamster. Antimony was more preferably accumulated in rat red blood cells (RBCs) than hamster RBCs. On the other hand, it has been reported that arsenic is bound to a specific cysteine residue in rat hemoglobin, which results in the substantial accumulation of arsenic in rat RBCs. These have led us to formulate the hypothesis that Sb, which belongs to the same group in the periodic table as arsenic, is also accumulated in the same manner as arsenic. However, because Sb was less accumulated than arsenic even in rat RBCs, Sb seemed to have less affinity for the cysteine residue than arsenic. Trivalent Sb showed greater accumulation than pentavalent Sb in rat RBCs. Consequently, species differences in Sb distribution between rat and hamster could be attributed to the affinity for the specific cysteine residue in hemoglobin.
Correlations between the concentrations of arsenic in scalp hair and in drinking water as well as in blood and/or urine have been reported. These correlations clearly show exposure-absorption-excretion relationships. In addition, arsenic metabolites such as monomethylarsonic acid and dimethylarsinic acid have been identified and quantified in these tissues and fluids, leaving little doubt that elevated levels of arsenic in the hair can reflect systemic arsenic intoxication. Consequently, hair analysis has potential merit as a screening procedure for poisoning by arsenic. How ever, questions regarding the exogenous versus the endogenous deposit ion of arsenic in the hair, and uncertainties about the normal level of arse- nic in the hair remain unresolved. Pending their resolution, determination of arsenic in hair should remain a screening tool, and clinical signs and symptoms should be employed to complete the diagnosis of arsenic poisoning
Background: Arsenic trioxide (ATO) is widely applied to treat acute promyelocytic leukemia (APL). To elucidate metabolism and toxicity of arsenic, we analyzed time course of arsenic species in red blood cells (RBCs) of APL patients.
Methods: Nine APL patients received ATO (0.16 mg/kg/day) through 18-h infusion. Blood was collected before daily administration (days 2 to 9), and at different time points on day 8. Inorganic arsenic (iAs), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were detected by HPLC-ICP-MS.
Results: Arsenic species reached Cmax at 18 h on day 8. Arsenicals gradually accumulated from 62.09 to 100.60 ng/g (iAs), from 9.07 to 32.20 ng/g (MMA), and from 0.68 to 6.20 ng/g (DMA), whereas their percentages remained almost constant. The general trend in red blood cells (RBCs) was iAs > MMA > DMA (P < 0.05) during administration. MMA was consistently the predominant methylated arsenic metabolite in RBCs of the 9 patients (P < 0.0001). iAs, MMA, and tAs (tAs = iAs + DMA + MMA) concentrations (P < 0.0001), MMA/DMA ratios (P = 0.0016) and iAs% (P = 0.0013) were higher in RBCs than in plasma.
Conclusions: Time course of arsenic species reveal kinetic characteristic of ATO metabolites in RBCs. Arsenic species accumulated with administration frequency. Arsenic species in RBCs were remarkably different from those in plasma. Time course of arsenic species in RBCs is important in ATO clinical application.
: Arsenic is ubiquitous in the environment and human exposure can occur from multiple possible routes including diet. Occupational medicine physicians asked to evaluate workers with elevated urine arsenic levels may be unaware that many sources of arsenic exposure are not work related. In this paper, we address arsenic exposure sources and pathways, adverse health effects of arsenic exposure and those subpopulations at increased risk, and the evaluation and treatment of those exposed to elevated arsenic levels.
This paper reviews how active research in West Bengal has unmasked the endemic arsenism that has detrimental effects on the health of millions of people and their offspring. It documents how the pathways of exposure to this toxin/poison have been greatly expanded through intensive application of groundwater in agriculture in the region within the Green Revolution framework. A goal of this paper is to compare and contrast the similarities and differences in arsenic occurrence in West Bengal with those of other parts of the world and assess the unique socio-cultural factors that determine the risks of exposure to arsenic in local groundwater. Successful intervention options are also critically reviewed with emphasis on integrative strategies that ensure safe water to the population, proper nutrition, and effective ways to reduce the transfer of arsenic from soil to crops. While no universal model may be suited for the vast areas of the world affected with by natural contamination of groundwater with arsenic, we have emphasized community-specific sustainable options that can be adapted. Disseminating scientifically correct information among the population coupled with increased community level participation and education are recognized as necessary adjuncts for an engineering intervention to be successful and sustainable.
A method for analysis of toxicologically important arsenic species in blood plasma and whole blood by selective hydride generation with cryotrapping (HG-CT) coupled either to atomic absorption spectrometry (AAS) with a quartz multiatomizer or to inductively coupled plasma mass spectrometry (ICPMS) has been validated. Sample preparation, which involved only 5 times dilution with addition of Triton X-100, Antifoam B, and l-cysteine, suppressed excessive foaming in a hydride generator. Calibration slopes for whole blood and blood plasma spiked with arsenate, monomethylarsonate, and dimethylarsinate at 0.25–1 μg L–1 As and 0.025–0.1 μg L–1 As for AAS and ICPMS detection, respectively, did not differ from slopes in aqueous solutions. HG-CT-AAS was used to analyze samples with elevated levels of arsenic species-blood plasma from patients treated with arsenic trioxide for acute promyelocytic leukemia and whole blood from mice fed an arsenic-containing diet. A good agreement between results of the direct analysis and analysis after mild digestion in phosphoric acid proved the good efficiency of the direct HG-CT procedure for the arsenic species in these types of biological samples. In the next step, plasma and whole blood from healthy donors that were spiked with the plasma from leukemia patients at levels of 0.15–0.4 μg L–1 As were analyzed by direct HG-CT-ICPMS. Good recoveries for all species even at these low levels (88–104%) were obtained. Limits of detection in blood and plasma were 0.014 μg L–1 for inorganic arsenic and below 0.002 μg L–1 As for methylated arsenic species. Thus, the ultrasensitive direct HG-CT-ICPMS method is uniquely suited for analyses of blood plasma and whole blood from individuals at low exposure levels.
Arsenic (As) is a notoriously toxic pollutant of health concern worldwide with potential risk of cancer induction, but meanwhile it is used as medicines for the treatment of different conditions including hematological cancers. Arsenic can undergo extensive metabolism in biological systems, and both toxicological and therapeutic effects of arsenic compounds are closely related to their metabolism. Recent studies have identified methylated thioarsenicals as a new class of arsenic metabolites in biological systems after exposure of inorganic and organic arsenicals, including arsenite, dimethylarsinic acid (DMAV), dimethylarsinous glutathione (DMAIIIGS), and arsenosugars. The increasing detection of thiolated arsenicals, including monomethylmonothioarsonic acid (MMMTAV), dimethylmonothioarsinic acid (DMMTAV) and its glutathione conjugate (DMMTAV(GS)), and dimethyldithioarsinic acid (DMDTAV) suggests that thioarsenicals may be important metabolites and play important roles in arsenic toxicity and therapeutic effects. Here we summarized the reported occurrence of thioarsenicals in biological systems, the possible formation pathways of thioarsenicals, and their toxicity, and discussed the biological implications of thioarsenicals on arsenic metabolism, toxicity, and therapeutic effects.
Two key arsenic metabolites, monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII), have recently been detected in human urine. There is an increasing interest in the speciation of these metabolites in humans because of their demonstrated effects on cellular toxicity and DNA damage. However, there is no information on the oxidative stability of these arsenic species. It is not known whether and to what extent these trivalent metabolites are changed during sample handling and storage. The objective of this study was to demonstrate the oxidative conversion of these arsenic species during sample storage. We compared the effects of the storage temperature (25, 4, and −20°C) and storage duration (up to 5 months) on the stability of MMAIII and DMAIII in de-ionized water and in human urine. We used HPLC with hydride generation atomic fluorescence detection for the speciation
of arsenic. This method provided sub-µg L−1 to low-µg L−1 detection limits for each arsenic species. We found that the oxidation of MMAIII and DMAIII was matrix and temperature dependent. Low temperature conditions (4 and −20°C ) improved the stability of these arsenic species over the room temperature storage condition. MMAIII in de-ionized water was relatively stable for almost 4 months, when stored at 4 or −20°C with less than 10% of MMAIII oxidized to MMAV. In contrast, most of MMAIII
(>90%) in urine was oxidized to MMAV over the 5 month period under the 4 or −20°C storage condition. At 25°C, MMAIII in urine was completely oxidized to MMAV within a week. DMAIII in de-ionized water was stable for only 2–3 days,
being rapidly oxidized to DMAV. DMAIII in urine was completely oxidized to DMAV within a day at 4 or −20°C. The conversion of DMAIII to DMAV in urine at 25°C was complete in 17 h. These results show that MMAIII and DMAIII are much less stable than other arsenic species, and their stability depends on sample matrix and temperature.
Biomethylation is considered a major detoxification pathway for inorganic arsenicals (iAs). According to the postulated metabolic scheme, the methylation of iAs yields methylated metabolites in which arsenic is present in both pentavalent and trivalent forms. Pentavalent mono- and dimethylated arsenicals are less acutely toxic than iAs. However, little is known about the toxicity of trivalent methylated species. In the work reported here the toxicities of iAs and trivalent and pentavalent methylated arsenicals were examined in cultured human cells derived from tissues that are considered a major site for iAs methylation (liver) or targets for carcinogenic effects associated with exposure to iAs (skin, urinary bladder, and lung). To characterize the role of methylation in the protection against toxicity of arsenicals, the capacities of cells to produce methylated metabolites were also examined. In addition to human cells, primary rat hepatocytes were used as methylating controls. Among the arsenicals examined, trivalent monomethylated species were the most cytotoxic in all cell types. Trivalent dimethylated arsenicals were at least as cytotoxic as trivalent iAs (arsenite) for most cell types. Pentavalent arsenicals were significantly less cytotoxic than their trivalent analogs. Among the cell types examined, primary rat hepatocytes exhibited the greatest methylation capacity for iAs followed by primary human hepatocytes, epidermal keratinocytes, and bronchial epithelial cells. Cells derived from human bladder did not methylate iAs. There was no apparent correlation between susceptibility of cells to arsenic toxicity and their capacity to methylate iAs. These results suggest that (1) trivalent methylated arsenicals, intermediary products of arsenic methylation, may significantly contribute to the adverse effects associated with exposure to iAs, and (2) high methylation capacity does not protect cells from the acute toxicity of trivalent arsenicals.
The aim of this investigation was to study the distribution of arsenic species in human organs following fatal acute intoxication by arsenic trioxide. The collected autopsy samples of most organs were ground and dried, and the total arsenic was measured by electrothermal atomic absorption spectrometry (ETAAS). The arsenic species--inorganic arsenic, in the form of arsenite [As(III)] and arsenate [As(V)], and its metabolites [monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)]--were quantified by ETAAS after extraction with methanol/water (1:1, by volume) and separation by HPLC. The results indicate that after acute intoxication, the liver and kidneys show the highest concentrations of total arsenic and that the total concentration in blood is 7- to 350-fold less concentrated than in organs. In all organs, As(III) is the predominant species, and MMA is more concentrated than DMA. MMA and DMA are more prevalent in lipidic organs (49% of total arsenic) compared with other organs (25% of total arsenic). As(V) was found in small quantities in the liver, kidneys, and blood.
Stability of chemical speciation during sample handling and storage is a prerequisite to obtaining reliable results of trace element speciation analysis. There is no comprehensive information on the stability of common arsenic species, such as inorganic arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid, dimethylarsinic acid, and arsenobetaine, in human urine.
We compared the effects of the following storage conditions on the stability of these arsenic species: temperature (25, 4, and -20 degrees C), storage time (1, 2, 4, and 8 months), and the use of additives (HCl, sodium azide, benzoic acid, benzyltrimethylammonium chloride, and cetylpyridinium chloride). HPLC with both inductively coupled plasma mass spectrometry and hydride generation atomic fluorescence detection techniques were used for the speciation of arsenic.
We found that all five of the arsenic species were stable for up to 2 months when urine samples were stored at 4 and -20 degrees C without any additives. For longer period of storage (4 and 8 months), the stability of arsenic species was dependent on urine matrices. Whereas the arsenic speciation in some urine samples was stable for the entire 8 months at both 4 and -20 degrees C, other urine samples stored under identical conditions showed substantial changes in the concentration of As(III), As(V), monomethylarsonic acid, and dimethylarsinic acid. The use of additives did not improve the stability of arsenic speciation in urine. The addition of 0.1 mol/L HCl (final concentration) to urine samples produced relative changes in inorganic As(III) and As(V) concentrations.
Low temperature (4 and -20 degrees C) conditions are suitable for the storage of urine samples for up to 2 months. Untreated samples maintain their concentration of arsenic species, and additives have no particular benefit. Strong acidification is not appropriate for speciation analysis.
The enzymatically catalyzed oxidative methylation of As yields methylated arsenicals that contain pentavalent As (As(V)). Because trivalent As (As(III)) is the favored substrate for this methyltransferase, methylated arsenicals containing As(V) are reduced to trivalency in cells. Methylated arsenicals that contain As(III) are extremely potent inhibitors of NADPH-dependent flavoprotein oxidoreductases and potent cytotoxins in many cell types. Therefore, the formation of methylated arsenicals that contain As(III) may be properly regarded as an activation step, rather than a means of detoxification. Recognition of the role of methylated arsenicals that contain As(III) in the toxicity and metabolism of As emphasizes the need for analytical methods to detect and quantify these species in biological samples. Hence, a method was developed to exploit pH-dependent differences in the generation of arsines from inorganic and methylated arsenicals that contain either As(V) or As(III). Reduction with borohydride at pH 6 generated arsines from inorganic As(III), methyl As(III), and dimethyl As(III), but not from inorganic As(V), methyl As(V), and dimethyl As(V). Reduction with borohydride at pH 2 or lower generated arsines from arsenicals that contained either As(V) or As(III). Arsines are trapped in a liquid nitrogen-cooled gas chromatographic trap, which is subsequently warmed to allow separation of the hydrides by their boiling points. Atomic absorption spectrophotometry is used to detect and quantify the arsines. The detection limits (ng As ml(-1)) for inorganic As(III), methyl As(III), and dimethyl As(III) are 1.1, 1.2, and 6.5, respectively. This method has been applied to the analysis of arsenicals in water, human urine, and cultured cells. Both methyl As(III) and dimethyl As(III) are detected in urine samples from individuals who chronically consumed inorganic As-contaminated water and in human cells exposed in vitro to inorganic As(III). The reliable quantitation of inorganic and methylated arsenicals that contain As(III) in biological samples will aid the study of the toxicity of these species and may provide a new biomarker of the effects of chronic exposure to As.
Recent research of the metabolism and biological effects of arsenic has profoundly changed our understanding of the role of metabolism in modulation of toxicity and carcinogenicity of this metalloid. Historically, the enzymatic conversion of inorganic arsenic to mono- and dimethylated species has been considered a major mechanism for detoxification of inorganic arsenic. However, compelling experimental evidence obtained from several laboratories suggests that biomethylation, particularly the production of methylated metabolites that contain trivalent arsenic, is a process that activates arsenic as a toxin and a carcinogen. This article summarizes this evidence and provides new data on a) the toxicity of methylated trivalent arsenicals in mammalian cells, b) the effects of methylated trivalent arsenicals on gene transcription, and c) the mechanisms involved in arsenic methylation in animal and human tissues.
In this study we report on the finding of monomethylarsonous acid [MMA(III)] in human urine. This newly identified arsenic species is a key intermediate in the metabolic pathway of arsenic biomethylation, which involves stepwise reduction of pentavalent to trivalent arsenic species followed by oxidative addition of a methyl group. Arsenic speciation was carried out using ion-pair chromatographic separation of arsenic compounds with hydride generation atomic fluorescence spectrometry detection. Speciation of the inorganic arsenite [As(III)], inorganic arsenate [As(V)], monomethylarsonic acid [MMA(V)], dimethylarsinic acid [DMA(V)], and MMA(III) in a urine sample was complete in 5 min. Urine samples collected from humans before and after a single oral administration of 300 mg sodium 2,3-dimercapto-1-propane sulfonate (DMPS) were analyzed for arsenic species. MMA(III) was found in 51 out of 123 urine samples collected from 41 people in inner Mongolia 0-6 hr after the administration of DMPS. MMA(III)in urine samples did not arise from the reduction of MMA(V) by DMPS. DMPS probably assisted the release of MMA(III) that was formed in the body. Along with the presence of MMA(III), there was an increase in the relative concentration of MMA(V) and a decrease in DMA(V) in the urine samples collected after the DMPS ingestion.
A study of arsenic speciation in blood plasma of patients undergoing renal dialysis has been performed using HPLC coupled with ICP MS. It was found that the only detectable arsenic species present in the plasma was arsenobetaine. The limit of detection using an injection volume of 175 µl was found to be 0.25 ng of arsenic as arsenobetaine. Spiking experiments demonstrated recoveries of approximately 100%. In the absence of certified reference materials or an alternative technique, we believe this was the best way to demonstrate that the method was reliable and accurate. Arsenobetaine concentrations in pre-dialysis plasma were similar to those for the healthy volunteers, although after dialysis the concentrations were significantly reduced. It is thus concluded that, except for a few patients, dialysis removed the arsenobetaine efficiently (hence preventing an accumulation of arsenic) and that no biotransformations were occurring. The exceptions to this conclusion were in a few patients whose arsenobetaine levels increased marginally after dialysis, but this was attributed to the levels both pre- and post-dialysis being very close to the detection limit. Copyright © 1999 John Wiley & Sons, Ltd.
A study of arsenic speciation in blood plasma of patients undergoing renal dialysis has been performed using HPLC coupled with ICP MS. It was found that the only detectable arsenic species present in the plasma was arsenobetaine. The limit of detection using an injection volume of 175 µl was found to be 0.25 ng of arsenic as arsenobetaine. Spiking experiments demonstrated recoveries of approximately 100%. In the absence of certified reference materials or an alternative technique, we believe this was the best way to demonstrate that the method was reliable and accurate. Arsenobetaine concentrations in pre-dialysis plasma were similar to those for the healthy volunteers, although after dialysis the concentrations were significantly reduced. It is thus concluded that, except for a few patients, dialysis removed the arsenobetaine efficiently (hence preventing an accumulation of arsenic) and that no biotransformations were occurring. The exceptions to this conclusion were in a few patients whose arsenobetaine levels increased marginally after dialysis, but this was attributed to the levels both pre- and post-dialysis being very close to the detection limit.
This paper presents an organized system for element-specific sample collection and handling of human blood (whole blood, serum or plasma, packed cells or erythrocytes) and urine also indicating a proper definition of the subject and sample. Harmonized procedures for collection, preparation, analysis and quality control are suggested. The aim is to assist scientists worldwide to produce comparable data which will be useful on a regional, national and international scale. The guidelines are directed to the elements aluminium, arsenic, cadmium, chromium, cobalt, copper, lead, lithium, manganese, mercury, nickel, selenium and zinc. These include the most important elements measured for their occupational or clinical significance, and serve as examples of principles that will guide development of methods for other elements in the future.
A new approach is described for the speciation of arsenic species including trivalent methylarsenicals in natural waters. Arsenious acid [As(III)], monomethylarsonous acid [MMAA(III)], and dinethylasinous acid (DMAA(III)] are separated from pestavaleat species by solvent extraction using diethylammonium diethyldithiocarbamate (DDDC) and determined by hydride generation atomic absorption spectrometry (HG-AAS) after cold trapping and Chromatographic separation. The detection limits for the trivalent species are about 13-17 pM. The som of concentrations of the trivalent and pentavalent species are determined directly by HG- AAS in aliquote of the same samples. This is the first report of trivalent methylaneakals being found and measured in natural waters.
Arsenic compounds were determined in 21 urine samples collected from a male volunteer. The volunteer was exposed to arsenic through either consumption of codfish or inhalation of small amounts of (CH3)3As present in the laboratory air. The arsenic compounds in the urine were separated and quantified with an HPLC–ICP–MS system equipped with a hydraulic high-pressure nebulizer. This method has a determination limit of 0.5 μg As dm−3 urine. To eliminate the influence of the density of the urine, creatinine was determined and all concentrations of arsenic compounds were expressed in μg As g−1 creatinine. The concentrations of arsenite, arsenate and methylarsonic acid in the urine were not influenced by the consumption of seafood. Exposure to trimethylarsine doubled the concentration of arsenate and increased the concentration of methylarsonic acid drastically (0.5 to 5 μg As g−1 creatinine). The concentration of dimethylarsinic acid was elevated after the first consumption of fish (2.8 to 4.3 μg As g−1 creatinine), after the second consumption of fish (4.9 to 26.5 μg As g−1 creatinine) and after exposure to trimethyl- arsine (2.9 to 9.6 μg As g−1 creatinine). As expected, the concentration of arsenobetaine in the urine increased 30- to 50-fold after the first consumption of codfish. Surprisingly, the concentration of arsenobetaine also increased after exposure to trimethylarsine, from a background of approximately 1 μg As g−1 creatinine up to 33.1 μg As g−1 creatinine. Arsenobetaine was detected in all the urine samples investigated. The arsenobetaine in the urine not ascribable to consumed seafood could come from food items of terrestrial origin that—unknown to us—contain arsenobetaine. The possibility that the human body is capable of metabolizing trimethyl- arsine to arsenobetaine must be considered. © 1997 by John Wiley & Sons, Ltd.
Humans are exposed via air, water and food to a number of different arsenic compounds, the physical, chemical, and toxicological properties of which may vary considerably. In people eating much fish and shellfish the intake of organic arsenic compounds, mainly arsenobetaine, may exceed 1000 μg As per day, while the average daily intake of inorganic arsenic is in the order of 10–20 μg in most countries. Arsenobetaine, and most other arsenic compounds in food of marine origin, e.g. arsenocholine, trimethylarsine oxide and methylarsenic acids, are rapidly excreted in the urine and there seem to be only minor differences in metabolism between animal species. Trivalent inorganic arsenic (AsIII) is the main form of arsenic interacting with tissue constituents, due to its strong affinity for sulfhydryl groups. However, a substantial part of the absorbed AsIII is methylated in the body to less reactive metabolities, methylarsonic acid (MMA) and dimethylarsinic acid (DMA), which are rapidly excreted in the urine. All the different steps in the arsenic biotransformation in mammals have not yet been elucidated, but it seems likely that the methylation takes place mainly in the liver by transfer of methyl groups from S-adenosylmethionine to arsenic in its trivalent oxidation state. A substantial part of absorbed arsenate (AsV) is reduced to AsIII before being methylated in the liver. There are marked species differences in the methylation of inorganic arsenic. In most animal species DMA is the main metabolite. Compared with human subjects, very little MMA is produced. The marmoset monkey is the only species which has been shown unable to methylate inorganic arsenic. In contrast to other species, the rat shows a marked binding of DMA to the hemoglobin, which results in a low rate of urinary excretion of arsenic.
Arsenobetaine was detected and quantified unambiguously in human plasma, serum and red blood cells by the combination of HPLC with ICP MS. Three different column conditions, i.e. two ionpair chromatographies for anionic (LC-1) and cationic (LC-2) compounds and gel-permeation chromatography (LC-3), were employed to confirm the assignment. Arsenobetaine was detected in every sample as a major component of the water-soluble arsenic compounds, with an increasing concentration in plasma < serum < blood cell fractions. It was the sole detectable arsenic compound in LC-1 and LC-2, while a broad peak corresponding to high-molecular-weight compounds was identified in addition to arsenobetaine in LC-3.
A review of the literature shows that a variety of washing procedures to remove external contamination from hair have been proposed, but as yet no standardised procedures are available. In this study, methods for the pre-treatment and determination of antimony, arsenic, cadmium, chromium, lead, mercury and selenium in human hair by inductively coupled plasma mass spectrometry (ICP-MS) are developed.Investigations of various washing procedures to remove external contaminants show that in unexposed hair samples cadmium, lead and mercury are significantly removed from hair using a 0.1 M HCl wash, with 87, 73 and 5%, respectively being washed-off. The removal of antimony, arsenic and chromium from unexposed hair is, however, more efficient with 1% (v/v) sodium lauryl sulphate (SLS), with 43, 40 and 13% of each element, respectively being washed-off. Selenium is not removed from the hair by any of the washing methods studied. For the digestion of hair samples a digestion mixture of nitric acid and hydrogen peroxide is used.Experiments with simulated sweat spiked with each of these elements show that exogenously bound chromium, cadmium and lead are removed after washing with 0.1 M HCl. In contrast, antimony, arsenic, selenium and mercury irreversibly bind and, thus, are not removed with any of the washing solutions investigated. This work also compares hair levels of these elements in an unexposed and exposed group using the method developed.
Inorganic arsenic may occur in biological systems as arsenite or arsenate, these two forms of arsenic differing markedly in both their chemical and biological properties (1). Preparations of arsenic-74 sometimes contain arsenic in both oxidation states. Lunde (2) reported that a sample of 74As-labeled sodium arsenate contained 60% of the arsenic-74 as arsenite, while Chan et al. (3) found that labeled arsenate samples contained 0.1 to 1% of an impurity which did not migrate with authentic arsenate during paper electrophoresis.The present paper describes simple procedures for purifying labeled samples of arsenic III and V, and for interconverting these two forms of arsenic.
In an attempt to establish a method for biological monitoring of inorganic arsenic exposure, the chemical species of arsenic were measured in the urine and hair of gallium arsenide (GaAs) plant and copper smelter workers. Determination of urinary inorganic arsenic concentration proved sensitive enough to monitor the low-level inorganic arsenic exposure of the GaAs plant workers. The urinary inorganic arsenic concentration in the copper smelter workers was far higher than that of a control group and was associated with high urinary concentrations of the inorganic arsenic metabolites, methylarsonic acid (MAA) and dimethylarsinic acid (DMAA). The results established a method for exposure level-dependent biological monitoring of inorganic arsenic exposure. Low-level exposures could be monitored only by determining urinary inorganic arsenic concentration. High-level exposures clearly produced an increased urinary inorganic arsenic concentration, with an increased sum of urinary concentrations of inorganic arsenic and its metabolites (inorganic arsenic + MAA + DMAA). The determination of urinary arsenobetaine proved to determine specifically the seafood-derived arsenic, allowing this arsenic to be distinguished clearly from the arsenic from occupational exposure. Monitoring arsenic exposure by determining the arsenic in the hair appeared to be of value only when used for environmental monitoring of arsenic contamination rather than for biological monitoring.
Because marine products are rich in arsenic, the concentration of arsenic in the human urine varies greatly with the state of ingestion of marine products. It has been revealed that inorganic arsenic is methylated in the human body to form MAA (methylarsonic acid) and DMAA (dimethylarsinic acid). It appears therefore that the arsenic present in the human urine is a mixture of the arsenic originating from marine products and the arsenic metabolized in vivo. Recent studies have shown that inorganic arsenic and methylarsenic compounds are quite different in toxicity and effect on the living body due to their difference in chemical species. Finding the chemical species of arsenic in the urine and hair of normal subjects will therefore provide valuable basal data for the biological monitoring of arsenic exposure and for toxicological studies of arsenic.
In vitro incubation of [74As]arsenite, -arsenate or -dimethylarsinic acid (DMA, the main metabolite of inorganic arsenic) with liver, lung and kidney homogenate of mice and rabbits showed that arsenite is the main form of arsenic bound to tissues. Injection of arsenite in mice and rabbits (0.04 mg As/kg body wt.) caused higher concentration of arsenic in the liver and the lungs than did the same dose of arsenate. This was less marked in the mice than in the rabbits, mainly due to the faster methylation to DMA. The relatively high degree of binding of arsenic to tissue constituents which also followed injection of arsenate may be explained by in vivo reduction to arsenite. The similar binding pattern after exposure to arsenite and arsenate indicates further that one and the same form of arsenic, arsenite, is retained independent of the form of exposure to inorganic arsenic. In contrast to the liver and lungs the kidneys showed a higher retention of arsenic after injection of arsenate than after injection of arsenite. Following injection of [74As]DMA in the animals excretion was essentially completed within 24 h, indicating low affinity for the tissues in vivo.
The objective of this study was to assess the arsenic concentrations in blood, urine, hair and nail samples as indicators of exposure, and to evaluate if differences in concentrations could help to explain why only a fraction of chronically exposed populations suffer signs and symptoms produced by arsenic. Results showed that As concentrations in all samples from the problem town were significantly higher (p<0.001) than those from the control population. The comparison between arsenic content in samples and time of exposure in individuals from the exposed town did not show a relationship. Exposed individuals with cutaneous signs had higher mean arsenic content in all samples than individuals without them. However, the difference was statistically significant only for urine and hair.
The urinary elimination of the metabolites of arsenic has been followed up as a function of time in volunteers who ingested a single oral dose of arsenic (500 microgram As) either as sodium arsenite (Asi), monomethylarsonate (MMA), or cacodylate (DMA). The excretion rate increased in the order Asi less than DMA less than MMA. After 4 days, the amount of arsenic excreted in urine represents 46, 78, and 75% of the ingested dose in the case of Asi, MMA and DMA, respectively. With regard to the in vivo biotransformations, it is concluded that DMA is excreted unchanged; MMA is slightly (13%) methylated into DMA while roughly 75% of the arsenic excreted after ingestion of Asi is methylated arsenic (about 1/3 as MMA and about 2/3 as DMA).
A large number of residents on the southwest coast of Taiwan suffer from an endemic peripheral vascular disease called blackfoot disease. Although the etiology has been investigated since 1958, the cause of blackfoot disease remains unknown. Certain substances contained in artesian well water have been implicated as causal factors, including arsenic as the predominant element. Data in this study demonstrated that in the well water collected from blackfoot disease regions of Taiwan there was a marked increase in total arsenic concentrations, with the predominant species being inorganic arsenical compounds. The concentrations of organic methyl arsenicals were present in minimal amounts. The excretion of total arsenic, inorganic arsenic, monomethylarsonic acid, and trimethylarsenic acid in the urine of patients afflicted with blackfoot disease was significantly higher than for control subjects. Further, in patients with blackfoot disease the concentrations of total arsenic and inorganic arsenic were markedly elevated in the hair and fingernails. Data suggest that blackfoot disease is associated with individuals ingesting well, water contaminated with arsenic primarily in the inorganic form and that hair, fingernails, or urine specimens serve as equally effective biomarkers of exposure. The fact that arsenic intoxication as manifested by blackfoot disease is still prevalent despite the stoppage of well-water consumption for two decades illustrates the persistent nature of arsenic action.
Because of the lack of data on the exposure to and toxic effects of inorganic arsenic during early human development, the transfer of arsenic to the fetus and suckling infant was studied in a native Andean population, living in the village San Antonio de los Cobres in the North west of Argentina, where the drinking water contains about 200 micrograms/liter. The concentration of arsenic in cord blood (median, 9 micrograms/liter) was almost as high as in maternal blood (median, 11 micrograms/liter), and there was a significant correlation between the two. Thus, at least in late gestation, arsenic is easily transferred to the fetus. The median concentration of arsenic in the placenta was 34 micrograms/kg, compared with 7 micrograms/kg previously reported for nonexposed women. Interestingly, essentially all arsenic in the blood plasma of both the newborns and their mothers was in the form of dimethylarsinic acid (DMA), the end product of inorganic arsenic metabolism. Similarly, about 90% of the arsenic in the urine of both the newborns and mothers in late gestation was present as DMA, compared with about 70% in nonpregnant women (p < 0.001). This may indicate that methylation of arsenic is increased during pregnancy and that DMA is the major form of arsenic transferred to the fetus. The increased methylation in late gestation was associated with lower arsenic concentrations in blood and higher concentrations in urine, compared with a few months postpartum. The arsenic concentrations in the urine of the infants decreased from about 80 micrograms/liter during the first 2 days of life to less than 30 micrograms/liter at 4.4 months (p = 0.025). This could be explained by the low concentrations of arsenic in the breast milk, about 3 micrograms/kg.
Inorganic arsenic is considered a high-priority hazard, particularly because of its potential to be a human carcinogen. In exposed human populations, arsenic is associated with tumors of the lung, skin, bladder, and liver. While it is known to be a human carcinogen, carcinogenesis in laboratory animals by this metalloid has never been convincingly demonstrated. Therefore, no animal models exist for studying molecular mechanisms of arsenic carcinogenesis. The apparent human sensitivity, combined with our incomplete understanding about mechanisms of carcinogenic action, create important public health concerns and challenges in risk assessment, which could be met by understanding the role of metabolism in arsenic toxicity and carcinogenesis. This symposium summary covers three critical major areas involving arsenic metabolism: its biodiversity, the role of arsenic metabolism in molecular mechanisms of carcinogenesis, and the impact of arsenic metabolism on human risk assessment. In mammals, arsenic is metabolized to mono- and dimethylated species by methyltransferase enzymes in reactions that require S-adenosyl-methionine (SAM) as the methyl donating cofactor. A remarkable species diversity in arsenic methyltransferase activity may account for the wide variability in sensitivity of humans and animals to arsenic toxicity. Arsenic interferes with DNA methyltransferases, resulting in inactivation of tumor suppressor genes through DNA hypermethylation. Other studies suggest that arsenic-induced malignant transformation is linked to DNA hypomethylation subsequent to depletion of SAM, which results in aberrant gene activation, including oncogenes. Urinary profiles of arsenic metabolites may be a valuable tool for assessing human susceptibility to arsenic carcinogenesis. While controversial, the idea that unique arsenic metabolic properties may explain the apparent non-linear threshold response for arsenic carcinogenesis in humans. In order to address these outstanding issues, further efforts are required to identify an appropriate animal model to elucidate carcinogenic mechanisms of action, and to define dose-response relationships.
The liver is considered a major site for methylation of inorganic arsenic (iAs). However, there is little data on the capacity of human liver to methylate iAs. This work examined the metabolism of arsenite (iAs(III)), arsenate (iAs(V)), methylarsine oxide (MAs(III)O), methylarsonic acid (MAs(V)), dimethylarsinous acid (DMAs(III)), and dimethylarsinic acid (DMAs(V)) in primary cultures of normal human hepatocytes. Primary rat hepatocytes were used as methylating controls. iAs(III) and MAs(III)O were metabolized more extensively than iAs(V) and MAs(V) by either cell type. Neither human nor rat hepatocytes metabolized DMAs(III) or DMAs(V). Methylation of iAs(III) by human hepatocytes yielded methylarsenic (MAs) and dimethylarsenic (DMAs) species; MAs(III)O was converted to DMAs. The total methylation yield (MAs and DMAs) increased over the range of 0.1 to 4 microM iAs(III). However, DMAs production was inhibited by iAs(III) in a concentration-dependent manner, and the DMAs/MAs ratio decreased. iAs(III) (10 and 20 microM) inhibited both methylation reactions. Inhibition of DMAs synthesis resulted in accumulation of iAs and MAs in human hepatocytes, suggesting that dimethylation is required for iAs clearance from cells. Methylation capacities of human hepatocytes obtained from four donors ranged from 3.1 to 35.7 pmol of iAs(III) per 10(6) cells per hour and were substantially lower than the methylation capacity of rat hepatocytes (387 pmol of iAs(III) per 10(6) cells per hour). The maximal methylation rates for either rat or human hepatocytes were attained between 0.4 and 4 microM iAs(III). In summary, (i) human hepatocytes methylate iAs, (ii) the capacities for iAs methylation vary among individuals and are saturable, and (iii) moderate concentrations of iAs inhibit DMAs synthesis, resulting in an accumulation of iAs and MAs in cells.
Methylation has been considered to be the primary detoxication pathway of inorganic arsenic. Inorganic arsenic is methylated by many, but not all animal species, to monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)), and dimethylarsinic acid (DMA(V)). The As(V) derivatives have been assumed to produce low toxicity, but the relative toxicity of MMA(III) remains unknown. In vitro toxicities of arsenate, arsenite, MMA(V), MMA(III), and DMA(V) were determined in Chang human hepatocytes. Leakage of lactate dehydrogenase (LDH) and intracellular potassium (K(+)) and mitochondrial metabolism of the tetrazolium salt XTT were used to assess cytotoxicity due to arsenic exposure. The mean LC50 based on LDH assays in phosphate media was 6 microM for MMA(III) and 68 microM for arsenite. Using the assay for K(+) leakage in phosphate media, the mean LC50 was 6.3 microM for MMA(III) and 19.8 microM for arsenite. The mean LC50 based on the XTT assay in phosphate media was 13.6 microM for MMA(III) and 164 microM for arsenite. The results of the three cytotoxicity assays (LDH, K(+), and XTT) reveal the following order of toxicity in Chang human hepatocytes: MMA(III) > arsenite > arsenate > MMA(V) = DMA(V). Data demonstrate that MMA(III), an intermediate in inorganic arsenic methylation, is highly toxic and again raises the question as to whether methylation of inorganic arsenic is a detoxication process.
Prolonged exposure to arsenic results in peripheral and cardiovascular manifestations, as does impaired production of endothelial nitric oxide (NO). In vitro studies have indicated that endothelial cells undergo damage by arsenic. However, no information has been available on the relationship between NO synthesis and chronic arsenic poisoning in humans. The present study was designed to reveal this question. The subjects were 33 habitants who continued to drink well water containing high concentrations of inorganic arsenic (mean value = 0.41 microg/ml) for about 18 years in Inner Mongolia, China, and 10 other people who lived in this area but exposed to minimal concentrations of arsenic (mean value = 0.02 microg/ml) were employed as controls. Mean blood concentration of total arsenic was six times higher in exposed subjects than controls; 42.1 vs. 7.3 ng/ml, p <.001. Mean serum concentration of nitrite/nitrate, stable metabolites of endogenous NO, was lower in arsenic-exposed subjects than in controls: 24.7 vs. 51.6 microM, p<.001. In total samples, an inverse correlation with serum nitrite/nitrate levels was strong for blood inorganic arsenic (r = -0.52, p <.001) and less strong for its metabolites, monomethyl arsenic (r = -0.45, p<.005) and dimethyl arsenic (r = -0.37, p<.05). Furthermore, serum nitrite/nitrate concentration was significantly correlated with nonprotein sulfhydryl level in whole blood (r = 0.58, p<.001). In an in vitro study, we demonstrated that inorganic arsenite or arsenate suppresses the activity of endothelial NO synthase in human umbilical vein endothelial cells. These results suggest that long-term exposure to arsenic by drinking well water possibly reduces NO production in endothelial cells, resulting in a decrease in reduced nitrite/nitrate concentrations. Peripheral vascular disorders caused by arsenic may be attributable in part to impairment of NO production in vivo.
Monomethylarsonous acid (MMA(III)) has been detected for the first time in the urine of some humans exposed to inorganic arsenic in their drinking water. Our experiments have dealt with subjects in Romania who have been exposed to 2.8, 29, 84, or 161 microg of As/L in their drinking water. In the latter two groups, MMA(III) was 11 and 7% of the urinary arsenic while the monomethylarsonic acid (MMA(V)) was 14 and 13%, respectively. Of our 58 subjects, 17% had MMA(III) in their urine. MMA(III) was not found in urine of any members of the group with the lowest level of As exposure. If the lowest-level As exposure group is excluded, 23% of our subjects had MMA(III) in their urine. Our results indicate that (a) future studies concerning urinary arsenic profiles of arsenic-exposed humans must determine MMA(III) concentrations, (b) previous studies of urinary profiles dealing with humans exposed to arsenic need to be re-examined and re-evaluated, and (c) since MMA(III) is more toxic than inorganic arsenite, a re-examination is needed of the two hypotheses which hold that methylation is a detoxication process for inorganic arsenite and that inorganic arsenite is the major cause of the toxicity and carcinogenicity of inorganic arsenic.
Biomethylation is the major human metabolic pathway for inorganic arsenic, and the speciation of arsenic metabolites is essential to a better understanding of arsenic metabolism and health effects. Here we describe a technique for the speciation of arsenic in human urine and demonstrate its application to the discovery of key arsenic metabolic intermediates, monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII), in human urine. The study provides a direct evidence in support of the proposed arsenic methylation pathway in the human. The finding of MMAIII and DMAIII in human urine, along with recent studies showing the high toxicity of these arsenicals, suggests that the usual belief of arsenic detoxification by methylation needs to be reconsidered. The arsenic speciation technique is based on ion pair chromatographic separation of arsenic species on a 3-micron particle size column at 50 degrees C followed by hydride generation atomic fluorescence detection. Speciation of MMAIII, DMAIII, arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMAV), and dimethylarsinic acid (DMAV) in urine samples is complete in 6 min with detection limits of 0.5-2 micrograms/L. There is no need for any sample pretreatment. The capability of rapid analysis of trace levels of arsenic species, which resulted in the findings of the key metabolic intermediates, makes the technique useful for routine arsenic speciation analysis required for toxicological and epidemiological studies.
The formation of monomethylarsonous acid (MMA(III)) by tissue homogenates of brain, bladder, spleen, liver, lung, heart, skin, kidney, or testis of male Golden Syrian hamsters was assessed using [(14)C]monomethylarsonic acid (MMA(V)) as the substrate for MMA(V) reductase. The mean +/- SEM of MMA(V) reductase specific activities (nanomoles of MMA(III) per milligram of protein per hour) were as follows: brain, 91.4 +/- 3.0; bladder, 61.8 +/- 3.7; spleen, 30.2 +/- 5.4; liver, 29.8 +/- 1.4; lung, 21.5 +/- 0.8; heart, 19.4 +/- 1.5; skin, 14.7 +/- 1.6; kidney, 10.6 +/- 0.4; and testis, 9.8 +/- 0.6. The concentrations of MMA(III) in male Golden Syrian hamster livers were determined 15 h after administration of a single intraperitoneal dose of 145 microCi of [(73)As]arsenate (2 mg of As/kg of body weight). Trivalent arsenic species (arsenite, MMA(III), and dimethylarsinous acid, DMA(III)) were extracted from liver homogenates using carbon tetrachloride (CCl(4)) and 20 mM diethylammonium salt of diethyldithiocarbamic acid (DDDC). Pentavalent arsenicals (arsenate, MMA(V), and dimethylarsinic acid, DMA(V)) remained in the aqueous phase. The organic and the aqueous phases then were analyzed by HPLC. Metabolites of inorganic arsenate present in hamster liver after 15 h were observed in the following concentrations (nanograms per gram of liver +/- SEM): MMA(III), 38.5 +/- 2.9; DMA(III), 49.9 +/- 10.2; arsenite, 35.5 +/- 3.0; arsenate, 118.2 +/- 8.7; MMA(V), 31.4 +/- 2.8; and DMA(V), 83.5 +/- 6.7. This first-time identification of MMA(III) and DMA(III) in liver after arsenate exposure indicates that the significance of arsenic species in mammalian tissue needs to be re-examined and re-evaluated with respect to their role in the toxicity and carcinogenicity of inorganic arsenic.
A speciation technique for arsenic has been developed using an anion-exchange high-performance liquid chromatography/inductively coupled argon plasma mass spectrometer (HPLC/ICP MS). Under optimized conditions, eight arsenic species [arsenocholine, arsenobetaine, dimethylarsinic acid (DMA(V)), dimethylarsinous acid (DMA(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)), arsenite (As(III)), and arsenate (As(V))] can be separated with isocratic elution within 10 min. The detection limit of arsenic compounds was 0.14-0.33 microg/L. To validate the method, Standard Reference Material in freeze-dried urine, SRM-2670, containing both normal and elevated levels of arsenic was analyzed. The method was applied to determine arsenic species in urine samples from three arsenic-affected districts of West Bengal, India. Both DMA(III) and MMA(III) were detected directly (i.e., without any prechemical treatment) for the first time in the urine of some humans exposed to inorganic arsenic through their drinking water. Of 428 subjects, MMA(III) was found in 48% and DMA(III) in 72%. Our results indicate the following. (1) Since MMA(III) and DMA(III) are more toxic than inorganic arsenic, it is essential to re-evaluate the hypothesis that methylation is the detoxification pathway for inorganic arsenic. (2) Since MMA(V) reductase with glutathione (GSH) is responsible for conversion of MMA(V) to MMA(III) in vivo, is DMA(V) reductase with GSH responsible for conversion of DMA(V) to DMA(III) in vivo? (3) Since DMA(III) forms iron-dependent reactive oxygen species (ROS) which causes DNA damage in vivo, DMA(III) may be responsible for arsenic carcinogenesis in human.
The reactivities of methyloxoarsine (MAs(III)) and iododimethylarsine (DMAs(III)), two methylated trivalent arsenicals, toward supercoiled phiX174 RFI DNA were assessed using a DNA nicking assay. The induction of DNA damage by these compounds in vitro in human peripheral lymphocytes was assessed using a single-cell gel (SCG, "comet") assay. Both methylated trivalent arsenicals were able to nick and/or completely degrade phiX174 DNA in vitro in 2 h incubations at 37 degrees C (pH 7.4) depending on concentration. MAs(III) was effective at nicking phiX174 DNA at 30 mM; however, at 150 microM DMAs(III), nicking could be observed. Exposure of phiX174 DNA to sodium arsenite (iAs(III); from 1 nM up to 300 mM), sodium arsenate (from 1 microM to 1 M), and the pentavalent arsenicals, monomethylarsonic acid (from 1 microM to 3 M) and dimethylarsinic acid (from 0.1 to 300 mM), did not nick or degrade phiX174 DNA under these conditions. In the SCG assay in human lymphocytes, methylated trivalent arsenicals were much more potent than any other arsenicals that were tested. On the basis of the slopes of the concentration-response curve for the tail moment in the SCG assay, MAs(III) and DMAs(III) were 77 and 386 times more potent than iAs(III), respectively. Because methylated trivalent arsenicals were the only arsenic compounds that were observed to damage naked DNA and required no exogenously added enzymatic or chemical activation systems, they are considered here to be direct-acting forms of arsenic that are genotoxic, though they are not, necessarily, the only genotoxic species of arsenic that could exist.
There is strong evidence from epidemiologic studies of an association between chronic exposure to inorganic arsenic (iAs) and hyperpigmentation, hyperkeratosis, and neoplasia in the skin. Although it is generally accepted that methylation is a mechanism of arsenic detoxification, recent studies have suggested that methylated arsenicals also have deleterious biological effects. In these studies we compare the effects of inorganic arsenicals (arsenite (iAs(III)) and arsenate (iAs(V))) and trivalent and pentavalent methylated arsenicals (methylarsine oxide (MAs(III)O), complex of dimethylarsinous acid with glutathione (DMAs(III)GS), methylarsonic acid (MAs(V)), and dimethylarsinic acid (DMAs(V))) in human keratinocyte cultures. Viability testing showed that the relative toxicities of the arsenicals were as follows: iAs(III) > MAs(III)O > DMAs(III)GS > DMAs(V) > MAs(V) > iAs(V). Trivalent arsenicals induced an increase in cell proliferation at concentrations in the 0.001 to 0.01 microM range, while at high concentrations (>0.5 microM) cell proliferation was inhibited. Pentavalent arsenicals did not stimulate cell proliferation. As seen in the viability studies, the methylated forms of As(V) were more cytotoxic than iAs(V). Exposure to low doses of trivalent arsenicals stimulated secretion of the growth-promoting cytokines, granulocyte macrophage colony stimulating factor and tumor necrosis factor-alpha. DMAs(V) reduced cytokine secretion at concentrations at which proliferation and viability were not affected. These data suggest that methylated arsenicals, products of the metabolic conversion of inorganic arsenic, can significantly affect viability and proliferation of human keratinocytes and modify their secretion of inflammatory and growth-promoting cytokines.
The animal species difference in the metabolism of arsenic was studied from the viewpoint of the mechanism underlying its distribution in the form of dimethylated arsenic in red blood cells (RBCs). Dimethylarsinic (DMA(V)) and dimethylarsinous (DMA(III)) acids were incubated with rat, hamster, mouse, and human RBCs, and the uptake rates and chemical forms of arsenic were determined. Although DMA(V) was practically not or taken up slowly by RBCs of all the present animal species, DMA(III) was taken efficiently in the order of rat > hamster > human, RBCs of mice taking it up less efficiently and with a different pattern from the former three animals. Further, although DMA(III) taken up by rat RBCs was retained, that by hamster ones was effluxed in the form of DMA(V). The uptake of DMA(III) and efflux of DMA(V) took place much more slowly in human RBCs than rat and hamster ones. The uptake of DMA(III) by RBCs was inhibited on the oxidation of glutathione with diamide. Incubation of DMA(III), but not of DMA(V), with a hemolysate produced a high molecular weight complex, which increases in the presence of glutathione, suggesting that DMA(III) taken up by RBCs is retained through the formation of a complex with protein(s) specific to animal species, and effluxed from RBCs after being oxidized to DMA(V). These results indicate that DMA is taken up by RBCs in the form of DMA(III), and that the uptake and efflux rates are dependent on the animal species, the effluxed arsenic being DMA(V). The present results suggest that the uptake of DMA by RBCs is an additional contributing factor to the animal species difference in the metabolism of arsenic in addition to the reduction and methylation capacity in the liver.
Although it has been known for decades that humans and many other species convert inorganic arsenic to mono- and dimethylated metabolites, relatively little attention has been given to the biological effects of these methylated products. It has been widely held that inorganic arsenicals were the species that accounted for the toxic and carcinogenic effects of this metalloid and that methylation was properly regarded as a mechanism for detoxification of arsenic. Elucidation of the metabolic pathway for arsenic has changed our understanding of the significance of methylation. Both methylated and dimethylated arsenicals that contain arsenic in the trivalent oxidation state have been identified as intermediates in the metabolic pathway. These compounds have been detected in human cells cultured in the presence of inorganic arsenic and in urine of individuals who were chronically exposed to inorganic arsenic. Methylated and dimethylated arsenicals that contain arsenic in the trivalent oxidation state are more cytotoxic, more genotoxic, and more potent inhibitors of the activities of some enzymes than are inorganic arsenicals that contain arsenic in the trivalent oxidation state. Hence, it is reasonable to describe the methylation of arsenic as a pathway for its activation, not as a mode of detoxification. This review summarizes the current knowledge of the processes that control the formation and fate of the methylated metabolites of arsenic and of the biological effects of these compounds. Given the considerable interest in the dose-response relationships for arsenic as a toxin and a carcinogen, understanding the metabolism of arsenic may be critical to assessing the risk associated with chronic exposure to this element.
The metabolic pathways for arsenic were precisely studied by determining the metabolic balance and chemical species of arsenic to gain an insight into the mechanisms underlying the animal species difference in the metabolism and preferential accumulation of arsenic in red blood cells (RBCs) in rats. Male Wistar rats were injected intravenously with a single dose of arsenite (iAs III) at 2.0 mg of As/kg of body weight, and then the time-dependent changes in the concentrations of arsenic in organs and body fluids were determined. Furthermore, arsenic in the bile was analyzed on anion and cation exchange columns by high-performance liquid chromatography-inductively coupled argon plasma mass spectrometry (HPLC-ICP MS). The metabolic balance and speciation studies revealed that arsenic is potentially transferred to the hepato-enteric circulation through excretion from the liver in a form conjugated with glutathione (GSH). iAs III is methylated to mono (MMA)- and dimethylated (DMA) arsenics in the liver during circulation in the conjugated form [iAs III(GS) 3], and a part of MMA is excreted into the bile in the forms of MMA III and MMA v, the former being mostly in the conjugated form [CH 3As III(GS) 2], and the latter being in the nonconjugated free form. DMA III and DMA v were not detected in the bile. In the urine, arsenic was detected in the forms of iAs III, arsenate, MMA v, and DMA v, iAs III being the major arsenic in the first 6-h-urine, and DMA v being increased in the second 6-h-urine. The present metabolic balance and speciation study suggests that iAs III is methylated in the liver during its hepato-enteric circulation through the formation of the GSH-cojugated form [iAs III(GS) 3], and MMA III and MMA v are partly excreted into the bile, the former being in the conjugated form [CH 3As III(GS) 2]. DMA is not excreted into the bile but into the bloodstream, accumulating in RBCs, and then excreted into the urine mostly in the form of DMA v in rats.
The diagnosis and evaluation of chronic arsenic poisoning remains a difficult task. Clinical indicators are crude measures, and electromyography adds little to the picture. Blood arsenic levels are transitory, however urine levels are useful for monitoring ongoing exposure. Hair arsenic is useful as a confirmatory feature in chronic arsenic poisoning provided external contamination by arsenic can be excluded. The distribution of arsenic in cross sections or along the length of a shaft of hair cannot distinguish external contamination from arsenic derived from ingestion.
Although most edible vegetables do not accumulate As at a high rate, rice, carrots and certain others are exceptions. In addition to nutritional or toxicological considerations, the relatively high level and variety of As species present in rice make it a very suitable matrix for a candidate reference material representative of terrestrial biological samples.An analytical procedure was developed for As speciation in rice based on the use of a 1:1 methanol-water mixture for species extraction, an anion Hamilton PRPX-100 column (at pH 6, and phosphate mobile phase 10 mM), and a cation Hamilton PRP-X200 column (at pH 2.8 in pyridine formiate 4 mM) for species separation and final determination by HPLC-ICP-MS. The detection limits for dry flour rice expressed as As were 2 and 3 ng g(-1) for As(III) and AsB on the cation column and 3, 6 and 5 ng g(-1) for As(V), MMA and DMA, respectively, on the anion column. The methodology developed was applied to check the stability of As species in the water-methanol extract and also under different processing steps and storage time and temperature conditions. It was demonstrated that the As species in the water-methanol extracts stored at +4 degrees C remained stable for at least one month. Once the rice grains are ground, the MMA and As(V) species are not stable under any storage conditions probably due to microbiological activity. When ground rice is gamma-irradiated species remain stable although the AsB does not appear.
Nail and hair are rich in fibrous proteins, i.e., alpha-keratins that contain abundant cysteine residues (up to 22% in nail and 10-14% in hair). Although they are metabolically dead materials in the epidermis, the roots are highly influenced by the health status of the living beings and their analyses are used as a tool to monitor occupational and environmental exposure to toxic elements. The aims of the present study are to speciate arsenicals in human nail and hair and also to judge whether they should be used as a biomarker to arsenic (As) exposure and/or toxicity. All human fingernail and hair samples (n = 47) were collected from the As-affected area of West Bengal, India. Speciation of arsenicals in water extracts of fingernails and hair at 90 degrees C was carried out by HPLC-inductively coupled argon plasma mass spectrometer (ICP MS). Fingernails contained iAs(III) (58.6%), iAs(V) (21.5), MMA(V) (7.7), DMA(III) (9.2), and DMA(V) (3.0), and hair contained iAs(III) (60.9%), iAs(V) (33.2), MMA(V) (2.2), and DMA(V) (3.6). Fingernails contained DMA(III), but hair did not. The higher percentage of iAs(III) both in fingernails and hair than that of iAs(V) suggests more affinity of iAs(III) to keratin. Although all arsenicals in fingernails and hair correlate to As exposure positively, As speciation in fingernails seems to be more correlated with arsenism than that in hair. Exogenous contamination is a confounding factor for hair to consider it as a biomarker, whereas this is mostly absent in fingernails, which recommends it to be a better biomarker to arsenic exposure. DMA(III) content in fingernails and DMA(V) contents in both fingernails and hair could be the biomarker to As exposure.
Although the accumulation of arsenic (As) in human blood is linked with some diseases and with occupational exposure, there are few reports on speciation of As in blood. On the basis of our earlier article,[ 1 1.
Mandal , B. K. ,
Ogra , Y. ,
Anzai , K. and
Suzuki , K. T. 2004. Speciation of As in biological samples. Toxicol. Appl. Pharmacol., 198(4): 307–318. [CrossRef], [PubMed]View all references ] elevated level of arsenicals in human urine and blood were found in the ex-exposed population via As-containing drinking water. The aim of the present study was to get an insight on impact of As in foodstuffs on the people living in the As-affected areas. Moreover, speciation of arsenicals in urine, and water-samples found in arsenobetaine (AsB). Since sampling population (n = 25) was not taking any seafood, As in foodstuffs was thought to be the prime source for this discrepancy. So, speciation of methanol extract of freeze-dried red blood cells (RBCs) and foodstuffs, and trichloro acetic acid (TCA) treated plasma by high performance liquid chromatography-inductively coupled argon plasma mass spectrometer (HPLC-ICP MS) collected from the study population (n = 33) was carried out to support our hypothesis. Results showed that urine contained AsB (1.7%), arsenite (iAsIII) (14.3), arsenate (iAsV) (4.9), monomethylarsonous acid (MMAIII) (0.64), monomethylarsonic acid (MMAV) (13.6), dimethylarsinous acid (DMAIII) (7.7), and dimethylarsinic acid (DMAV) (65.4). Blood contained 21.3 μ g L− 1 (mean) As and of which 27.3% was in plasma and 72.7% in RBCs. RBCs contained AsB (21.6%) and DMAV (78.4) and blood plasma contained AsB (12.4%), iAsIII (25.9), MMAV (30.3), and DMAV (31.4). Furthermore, speciation of As in foodstuffs showed that most of them contained AsB (3.54–25.81 μ g kg− 1) (25.81–312.44 μ g kg− 1) along with iAsIII (9.62–194.93), iAsV (17.63–78.33), MMAV (9.47–73.22) and DMAV (13.43–101.15) that supported the presence of AsB and elevated As in urine and blood samples of the present study group. Inorganic As (iAs) predominates in rice (67.17–86.62%) and in spices (40–90.35%), respectively over organic As. So, As in the food chain is a real threat to human health.
Trivalent As compounds: preservation, and interaction with proteins
- X C Le
- Z Gong
- G Jiang
- X Lu
Le, X.C., Gong, Z., Jiang, G., Lu, X., 2002. Trivalent As compounds: preservation, and interaction with proteins. Paper presented at the Fifth International Conference on As Exposure and Health Effects, 14 – 18
Impact of foodarsenic on the people living in the arsenic-affected areas
- B K Mandal
- Y Ogra
- K Anzai
- K T Suzuki
Mandal, B.K., Ogra, Y., Anzai, K., Suzuki, K.T., 2003b. Impact of foodarsenic on the people living in the arsenic-affected areas. Unpublished
Data.
Arsenic and arsenic compounds
World Health Organisation (WHO), 2001. Arsenic and arsenic compounds.
Environmental Health Criteria No. 224, 2nd ed. World Health Organisation, Geneva, p. 521.
Arsenic in Drinking Water
National Research Council (NRC), 1999. Arsenic in Drinking Water. National Academy Press, Washington, DC, p. 330.
National Research Council (NRC), 2001. Arsenic in Drinking Water:
2001 Update. National Academy Press, Washington, DC, p. 244.