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PubMed1996

Speciation of arsenic in water samples by high-performance liquid chromatography-hydride generation-atomic absorption spectrometry at trace levels using a post-column reaction system.

Anion-exchange HPLC has been combined with hydride generation - atomic absorption spectrometry (HG-AAS) for the routine speciation of arsenite, arsenate, monomethylarsenic acid and dimethylarsinic acid. The sensitivity of the AAS-detection was increased by a post-column reaction system to achieve complete formation of volatile arsines from the methylated species and arsenate. The system allows the quantitative determination of 0.5 microg/l of each arsenic compound in water samples. The stability of synthetical and natural water containing arsenic at trace levels was investigated. To preserve stored water samples, a method for quantitative separation of arsenate at high pH-values with the basic anion-exchange resin Dowex 1x8 was developed.

Journal Article↗

PubMed1984

Significance of arsenic metabolic forms in urine. Part I: Chemical speciation.

The aim of this research has been to develop analytical procedures whereby the various chemical forms of arsenic present in urine can be distinguished and further data on the biotransformation of absorbed arsenic can be acquired. The separation of inorganic arsenic ( InAs ), monomethylarsonic acid ( MMAA ), and dimethylarsinic acid ( DMAA ) in urine was performed by ion-exchange chromatography on AG 50 W-X8 resin. Arsenic was then measured directly on the eluted fractions by atomic absorption spectrophotometry, after the reduction of arsenic to the correspondent arsine. In 160 subjects with no occupational exposure to arsenic compounds, InAs , MMAA , DMAA each accounted for about 10% of the total arsenic urinary excretion (17.2 +/- 11.1 micrograms/1), thus indicating that in the normal population over 60% of arsenic in urine is present in other organic forms. After eating marine food, there was a marked increase of urinary output of arsenic, but no increase was observed in InAs , MMAA and DMAA urinary excretion. In the biological monitoring of exposure to inorganic arsenic, particularly in the case of high urinary excretion values, the differentiation of the excreted forms of arsenic is necessary to establish with certainty the source (industrial or alimentary) of arsenic.

Adult↗

PubMed2005

Intracellular calcium disturbances induced by arsenic and its methylated derivatives in relation to genomic damage and apoptosis induction.

Arsenic and its methylated derivatives are contaminants of air, water, and food and are known as toxicants and carcinogens. Arsenic compounds are also being used as cancer chemotherapeutic agents. In humans, inorganic arsenic is metabolically methylated to mono-, di-, and trimethylated forms. Recent findings suggest that the methylation reactions represent a toxification rather than a detoxification pathway. In recent years, the correlation between arsenic exposure, cytotoxicity and genotoxicity, mutagenicity, and tumor promotion has been established, as well as the association of arsenic exposure with perturbation of physiologic processes, generation of reactive oxygen species, DNA damage, and apoptosis induction. Trivalent forms of arsenic have been found to induce apoptosis in several cellular systems with involvement of membrane-bound cell death receptors, activation of caspases, release of calcium stores, and changes of the intracellular glutathione level. It is well known that calcium ion deregulation plays a critical role in apoptotic cell death. A calcium increase in the nuclei might lead to toxic effects in the cell. In this review, we highlight the relationship between induced disturbances of calcium homeostasis, genomic damage, and apoptotic cell death caused by arsenic and its organic derivatives.

Animals↗

PubMed1977

Changes in the chemical speciation of arsenic following ingestion by man.

The concentrations of four chemical species of arsenic in urine were observed with time, after ingestion of three different chemical species of arsenic. The arsenic-rich substances ingested, including arsenite-rich wine, arsenate-rich drinking water, and crab meat which contained organo-arsenic compounds. After ingestion of arsenite-rich wine, approximately 10% of the arsenic was excreted as arsenite, but the majority of the arsenic was methylated to methylarsonic acid and dimethylarsinic acid and excreted. After ingestion of arsenate-rich water, elevated levels of both arsenate and dimethylarsinic acid were observed. When crab meat was ingested, none of these four arsenic species were observed at elevated levels until the urine was heated in 2N NaOH. After the hot base digestion, high levels of dimethylarsinic acid were detected in these samples. The apparent biological half-lives were on the order of 10 hr for inorganic arsenic and 30 hr for the methylated arsenic forms.

Arsenic↗

PubMed1999

[Arsenic efficient in acute promyelocytic leukemia].

Arsenic compounds have been utilised in medicine for over 2,000 years. Recently, arsenic trioxide has been shown to induce complete remission in up to 90% of patients with acute promyelocytic leukemia (APL), including those resistant to standard therapy. Randomised studies are currently investigating the potential clinical utility of this drug in APL. In vitro, arsenic trioxide exhibits antitumoral properties with respect to various other tumor species as well, although assessment of clinical effects will require further study. This article reviews clinical results and possible mechanisms of action of the drug.

Antineoplastic Agents↗

PubMed1995

[Duplicate study on the dietary intake of some metals/metalloids by children in Germany. I. Arsenic and mercury].

The dietary intake of arsenic and mercury by 47 children (aged 5-8 years) living in West-Germany (Duisburg) is reported. Duplicate portions of all food and beverages were obtained on 2 days. Arsenic and mercury were measured by atomic absorption spectrometry under careful quality control. Results of are shown in the following table. [table: see text] Fish was consumed at 3 of 94 sampling days only. The arsenic and mercury intake on days with fish consumption was much higher compared with the other days (median, range): arsenic 8821; 4431-11954; mercury 123.7; 80, 0-167.5 ng/kg b.w. and day. The dietary arsenic and mercury intake was much lower than the FAO/WHO PTWI. For mercury the median intake amounted to 1.7% on days without and to 16.6% on days with fish consumption, for arsenic on days without fish consumption to 5.2% PTWI (only for inorganic arsenic compounds established) and on days with fish consumption (in fish mainly organic arsenic occur) 411% of PTWI. Based on the PTWI our data indicate no health risks for German 5-8-year-old children due to arsenic and mercury dietary intake.

Animals↗

PubMed2004

Retention of arsenic and selenium compounds using limestone in a coal gasification flue gas.

Volatile arsenic and selenium compounds present in coals may cause environmental problems during coal combustion and gasification. A possible way to avoid such problems may be the use of solid sorbents capable of retaining these elements from flue gases in gas cleaning systems. Lime and limestone are materials that are extensively employed for the capture of sulfur during coal processing. Moreover, they have also proven to have good retention characteristics for arsenic and selenium during combustion. The aim of this work was to ascertain whether this sorbent is also useful for retaining arsenic and selenium species in gases produced in coal gasification. The study was carried out in a laboratory-scale reactor in which the sorbent was employed as a fixed bed, using synthetic gas mixtures. In these conditions, retention capacities for arsenic may reach 17 mg g(-1) in a gasification atmosphere free of H2S, whereas the presence of H2S implies a significant decrease in arsenic retention. In the case of selenium, H2S does not influence retention which may reach 65 mg g(-1). Post-retention sorbent characterization, thermal stability, and water solubility tests have shown that chemical reaction is one of the mechanisms responsible for the capture of arsenic and selenium, with Ca(AsO2)2 and CaSe being the main compounds formed.

Air Pollution↗

PubMed2006

On the first polyarsenic organic compound from nature: arsenicin A from the New Caledonian marine sponge Echinochalina bargibanti.

Reported here is the first polyarsenic compound ever found in nature. Denominated arsenicin A, it was isolated along a bioassay-guided fractionation of the organic extract of the poecilosclerid sponge Echinochalina bargibanti collected from the north-eastern coast of New Caledonia. In defining an adamantine-type polyarsenic structure for this compound, deceptively simple NMR spectra were complemented by extensive mass spectral analysis. However, it was only the synthesis of a model compound that provided the basis to discriminate structure 4 from other spectrally compatible structures for arsenicin A; to this end, a comparative ab initio simulation of IR spectra for the natural and the synthetic compounds was decisive. Arsenicin A is endowed with potent bactericidal and fungicidal activities on human pathogenic strains. All this may revive pharmacological interest in arsenic compounds while prompting us to rethink the arsenic cycle in nature.

Algorithms↗

PubMedDate not supplied

Understanding novel therapeutic agents for multiple myeloma.

Multiple myeloma, a B cell malignancy of the plasma cells, remains incurable. Advances in high-dose chemotherapy and stem cell transplantation have improved overall survival and event-free disease periods, but relapses are inevitable. New therapeutic agents have shown promising clinical use in patients with relapsed or refractory multiple myeloma. This article discusses the therapeutic applications of these novel agents with a focus on immunomodulatory drugs, proteasome inhibitors, and arsenic compounds.

Adjuvants, Immunologic↗

PubMed1991

Cytoprotective effect of reduced glutathione in arsenical-induced endothelial cell injury.

The effect of four arsenic compounds on cultured endothelial cell isolated from bovine carotid arteries was studied. Only trivalent arsenicals (arsenic trioxide and sodium m-arsenite), but not pentavalent arsenicals (arsenic acid and p-arsenilic acid), induced significant cell injury. Since the intracellular reduced glutathione (GSH) plays an important role in detoxication in mammalian cells, its effect on arsenical-induced cell injury was then studied. Pretreatment of cells with 500 microM GSH not only resulted in several-fold increase in the intracellular level of GSH but also effectively protected them against the injury caused by arsenic trioxide. After a pretreatment of cells with GSH for 3 h, the intracellular GSH reached a plateau. A longer pretreatment for 24 h still kept GSH at a very significant high level. The cell injury induced by arsenic trioxide was protected by GSH, and then cellular biosynthesis of PGI2 in culture was also increased. The cytoprotective effect and the stimulatory effect on PGI2 production, where both were dose-dependent on GSH, were in a strict reverse relationship. Aspirin treatment inhibited the PGI2 biosynthesis induced by GSH in the arsenic trioxide-induced cell injury, and significantly reduced the cytoprotective effect induced by GSH. These results suggest that the marked stimulation of endogenous PGI2 biosynthesis by GSH is the mechanism of the latter's cytoprotective effect on arsenic trioxide-induced endothelial cell injury.

Animals↗

PubMed1996

Role of arsenic as a reproductive toxin with particular attention to neural tube defects.

Arsenic has been recognized as a human toxicant for over 2000 years. More recently it has been readily accepted as a human carcinogen. Animal research has demonstrated arsenic's ability to have profound detrimental effects on the developing embryo in avian and mammalian species. This article comprehensively reviews the human and animal literature on the subject of the reproductive toxicity of arsenic. A variety of endpoints are considered, including spontaneous abortion, cardiovascular defects, and arsenic's role in the causation of neural tube defects (NTDs). A summary of the literature that has examined the various postulated mechanisms by which arsenic may produce NTDs is also considered. In addition, a discussion of literature relative to the presence of arsenic in the general environment and in the workplace is presented. This article reaches the conclusion that while further research is clearly needed, particularly on the potential toxicity of organic arsenical compounds, the current literature suggests it may be prudent and appropriate to treat inorganic arsenic as a probable human reproductive toxin.

Animals↗

PubMed2004

Arsenic trioxide for the treatment of myelodysplastic syndromes.

The impressive activity of arsenic trioxide in acute promyelocytic leukaemia (APL) has renewed the interest in this old compound. Arsenic trioxide targets the sulfhydryl groups present in many proteins involved in oncogenesis and has a broad spectrum of biological activities. This article will review the mechanisms of action of the drug and their relevance to the treatment of myelodysplastic syndrome (MDS), a disease for which no standard treatment currently exists. The early clinical experience has confirmed the activity of arsenic trioxide in MDS. The preliminary results of ongoing Phase II studies conducted in patients with MDS suggest that arsenic trioxide produces haematological improvement including durable transfusion independence in approximately 30% of patients. The current data are presented and discussed in this review.

Antineoplastic Agents↗

PubMed2005

Arsenic speciation in terrestrial birds from Yellowknife, Northwest Territories, Canada: the unexpected finding of arsenobetaine.

The surrounding area of Yellowknife, Northwest Territories, Canada, is known for naturally and anthropogenically elevated concentrations of arsenic. Five bird species (gray jay [Perisoreus canadensis], American tree sparrow [Spizella arborea], dark-eyed junco [Junco hyemalis], yellow-rumped warbler [Dendroica coronata], and spruce grouse [Dendragapus canadensis]) were collected from this area. Their tissues were analyzed for total arsenic and for arsenic species, allowing us to report, to our knowledge for the first time, the arsenic characterization in terrestrial birds. Total arsenic concentrations were determined in the terrestrial birds by inductively coupled plasma-optical emission spectrometry, whereas arsenic speciation analysis was performed using high-performance liquid chromatography-inductively coupled plasma-mass spectrometry. Total arsenic concentrations were substantially higher in the terrestrial bird species studied from Yellowknife compared with those reported previously in the literature. The primary arsenic species detected in two of the bird species studied was arsenobetaine. Normally, arsenobetaine is not formed or retained by terrestrial animals. Thus, the birds in the present study were thought to be highly adapted compared with other terrestrial animals, because they were able to form and/or retain this relatively nontoxic arsenic compound. This adaptation is thought to be a consequence of the elevated concentrations of arsenic in the Yellowknife area.

Animals↗

PubMed1985

Fate of foreign compounds in the environment.

The behavior of a foreign compound, once introduced into the environment, depends upon the nature of the compound and its interaction with the physical, chemical, and biological components of the ecosystem. It is important to understand the interaction of exogenous compounds with the ecosystem, because only in this way can the potential human health effects of these compounds be predicted. This paper outlines the various parameters that must be considered when predicting the fate of a compound in the environment. An example is then given which relates these factors to the distribution and fate of arsenical compounds.

Air Pollutants↗

PubMed2001

Arsenite is a cocarcinogen with solar ultraviolet radiation for mouse skin: an animal model for arsenic carcinogenesis.

Although epidemiological evidence shows an association between arsenic in drinking water and increased risk of skin, lung, and bladder cancers, arsenic compounds are not animal carcinogens. The lack of animal models has hindered mechanistic studies of arsenic carcinogenesis. Previously, this laboratory found that low concentrations of arsenite (the likely environmental carcinogen) which are not mutagenic can enhance the mutagenicity of other agents, including ultraviolet radiation (UVR). This enhancing effect appears to result from inhibition of DNA repair by arsenite. Recently we found that low concentrations of arsenite disrupted p53 function and upregulated cyclin D1. These results suggest that the failure to find an animal model for arsenic carcinogenesis is because arsenite is not a carcinogen per se, but rather acts as an enhancing agent (cocarcinogen) with a genotoxic partner. We tested this hypothesis with solar UVR as carcinogenic stimulus in hairless Skh1 mice. Mice given 10 mg/l sodium arsenite in drinking water for 26 weeks had a 2.4-fold increase in yield of tumors after 1.7 KJ/m(2) UVR three times weekly compared with mice given UVR alone. No tumors appeared in mice given arsenite alone. The tumors were mostly squamous cell carcinomas, and those occurring in mice given UVR plus arsenite appeared earlier and were much larger and more invasive than in mice given UVR alone. These results are consistent with the hypothesis that arsenic acts as a cocarcinogen with a second (genotoxic) agent by inhibiting DNA repair and/or enhancing positive growth signaling.

Animals↗

PubMed1990

Pathways of human exposure to arsenic in a community surrounding a copper smelter.

Several studies have found elevated levels of urinary arsenic among residents living near a copper smelter in Tacoma, Washington. To assess pathways of exposure to arsenic from the smelter, biological and environmental samples were collected longitudinally from 121 households up to 8 miles from the smelter. The concentration of inorganic and methylated arsenic compounds in spot urine samples was used as the primary measure of exposure to environmental arsenic. Urinary concentration of arsenic dropped off to a constant background level within one-half mile of the smelter in contrast to environmental concentrations, which decreased more steadily with increasing distance. Among all age-sex-specific groups in all areas, only children ages 0-6 living within one-half mile of the smelter had elevated levels of arsenic in urine. A separate analysis of data for these children suggests that hand-to-mouth activity was the primary source of exposure. Inhalation of ambient air and resuspension of contaminated soil were not important sources of exposure for children or adults.

Adolescent↗

PubMed2002

Arsenic species in an arsenic hyperaccumulating fern, Pityrogramma calomelanos: a potential phytoremediator of arsenic-contaminated soils.

The fern Pityrogramma calomelanos is a hyperaccumulator of arsenic that grows readily on arsenic-contaminated soils in the Ron Phibun district of southern Thailand. P. calomelanos accumulates arsenic mostly in the fronds (up to 8350 microg As g(-1) dry mass) while the rhizoids contain the lowest concentrations of arsenic (88-310 microg As g(-1) dry mass). The arsenic species in aqueous extracts of the fern and soil were determined by high performance liquid chromatography coupled to an inductively coupled plasma mass spectrometer (HPLC-ICPMS) which served as an arsenic specific detector. Only a small part of the arsenic (6.1-12%) in soil was extracted into water, and most of this arsenic (> 97%) was present as arsenate. The arsenic in the fern rhizoids was approximately 60% water-extractable, 95% of which was present as arsenate. In contrast, arsenic in the fern fronds was readily extracted into water (86-93%) and was present mainly as arsenite (60-72%) with the remainder being arsenate. Methylarsonate and dimethylarsinate were detected as trace constituents in only two fern samples. Preliminary estimates of phytoremediation potential suggest that P. calomelanos might remove approximately 2% of the soil arsenic load per year. With due consideration to the type of arsenic compounds present in the fern, and their water-solubility, the option of disposing high arsenic ferns at sea is raised for discussion.

Arsenic↗

PubMedDate not supplied

Speciation of arsenic in chicken meat by anion-exchange liquid chromatography with inductively coupled plasma-mass spectrometry.

A method was developed for speciation analysis of arsenic in chicken meat. Different procedures were optimized for the recovery of arsenic compounds without destroying the original compounds, and 2 anion-exchange liquid chromatography columns were compared for the separation of arsenic species prior to on-line detection by inductively coupled plasma-mass spectrometry. The 2 species found were dimethylarsinic acid (106 +/- 5 ng/g) and arsenobetaine (37 +/- 4 ng/g). The stability of arsenic species in a chicken meat candidate reference material for at least 12 months was demonstrated.

Animals↗