Organoarsenic Species Research Articles

The relative importance of waterborne and dietborne arsenic exposure on survival and growth of juvenile rainbow trout

Previous work demonstrated reduced growth of rainbow trout receiving diets containing environmentally relevant concentrations of arsenic, but did not address the relative and combined potency of waterborne and dietborne exposures. In the current study, juvenile rainbow trout were exposed for 28 d to a range of arsenic concentrations in water and in a live oligochaete diet, separately and in combination. In clean water, fish fed worms previously exposed to arsenate at 4 or 8 mg As/L showed pronounced reductions in growth, but fish exposed to these same water concentrations and a clean diet experienced less or no effect. Increasing waterborne arsenate to 16 or 32 mg As/L had substantial effects on both growth and survival, and simultaneous exposure via both routes intensified growth effects, but not mortality. Growth reduction was strongly correlated to total arsenic accumulation in the fish tissue, regardless of the route of exposure, but mortality was better correlated to waterborne arsenic concentration. The relative concentration of total arsenic in fish viscera and in the remaining carcass was not a useful indicator of exposure route. Speciation analysis showed that most arsenate was converted to arsenite within the worms, but organoarsenic species were not found. The greater toxicity of dietborne exposure when fish and prey were exposed to the same waterborne arsenate concentration emphasizes the need to address dietborne exposure when assessing the aquatic risks of arsenic contamination. This is of particular concern because risk from dietary exposure may occur at even lower water concentrations than used here when prey organisms are exposed for longer periods and via multiple routes.

Surface-Enhanced Raman Scattering (SERS) Characterization of Trace Organoarsenic Antimicrobials Using Silver/Polydimethylsiloxane Nanocomposites

Organoarsenic drugs such as roxarsone and 4-arsanilic acid are poultry feed additives widely used in US broilers to prevent coccidosis and to enhance growth and pigmentation. Despite their veterinary benefits there has been growing concern about their use because over 90% of these drugs are released intact into litter, which is often sold as a fertilizing supplement. The biochemical degradation of these antimicrobials in the litter matrix can release significant amounts of soluble As(III) and As(V) to the environment, representing a potential environmental risk. Silver/polydimethylsiloxane (Ag/PDMS) nanocomposites are a class of surfaceenhanced Raman scattering (SERS) substrates that have proven effective for the sensitive, reproducible, and field-adaptable detection of aromatic acids in water. The work presented herein uses for the first time Ag/PDMS nanocomposites as substrates for the detection and characterization of trace amounts of roxarsone, 4-arsanilic acid, and acetarsone in water. The results gathered in this study show that organoarsenic species are distributed into the PDMS surface where the arsonic acid binds onto the embedded silver nanoparticles, enhancing its characteristic 792 cm(-1) stretching band. The chemisorption of the drugs to the metal facilitates its detection and characterization in the parts per million to parts per billion range. An extensive analysis of the distinct spectroscopic features of each drug is presented with emphasis on the interactions of the arsonic acid, amino, and nitro groups with the metal surface. The benefits of SERS based methods for the study of arsenic drugs are also discussed.

Uptake of methylated arsenic by a polymeric adsorbent: Process performance and adsorption chemistry

Methylated arsenic in groundwater has caused a series of health problems to human beings. A N-methylglucamine modified chitosan polymeric adsorbent was successfully developed for efficient adsorption of methylated arsenic from water solution. Adsorption behaviors of two common methylated arsenic species, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), onto the adsorbent were investigated in this paper. The surface modification increased the adsorption capabilities for the arsenic. The uptake of MMA was higher than that of DMA throughout all pH values. The maximum adsorption capacities were 15.4 mg/g for MMA and 7.1 mg/g for DMA, exhibiting competitive advantages with other reported materials. The affinity of these arsenic species for the adsorbent followed a pattern of MMA > DMA. The adsorption equilibrium was achieved within 20 h. The uptake of MMA and DMA was dependent upon the concentration of background electrolytes, indicating the formation of outer-sphere complexes of both organoarsenic species with the adsorbent during the adsorption. The existence of natural organic matter and competitive anions cause decrease in the uptake of both arsenic species. Furthermore, the simultaneous uptake of organic contaminants such as humic acid was observed. The spectroscopic analysis demonstrated the strong attachment of both organic arsenic species onto the amine functional group of the adsorbent.

Speciation analysis in healthcare

The development of speciation methods enabling quantification and identification of elemental species has largely been driven by the need to differentiate between species of the same element which may be more toxic or less toxic, or essential to nutrition, often depending on the concentration. Examples of relevance to healthcare include inorganic arsenic, arsenobetaine and arsenocholine; chromium (VI) and chromium (III) and methylmercury and inorganic mercury in a variety of matrices such as food/supplements, biological tissues and clinical and environmental samples. Regulators and legislators are increasingly aware that the toxicity, environmental impact and health benefits of certain trace elements are more dependent on the amount and identity of their chemical forms than on the total concentration. However, most existing regulations are based on total element amount, although a few refer to element species. This is, to a large extent, owing to the limited availability of toxicological data, which demands ‘fit-for-purpose’ speciation methods. Such methods will become invaluable tools to support emerging regulation and human risk assessment. For speciation analysis applied to healthcare, approaches combining a high-resolution separation method, either offline or online, with element-specific detectors have been used for many years. However, it was not until the late 1980s that speciation researchers could have access to the detection power needed to measure low parts-per-billion and parts-per-trillion levels of elemental species in environmental, food and bioclinical samples. Since then, highperformance liquid chromatography–inductively coupled plasma (ICP)–mass spectrometry (MS) techniques have become the centrepiece of most elemental speciation work in this area. Also, the multielement and multi-isotope detection capability of ICP-MS enabled for the first time monitoring of the degree of species transformation (through isotope ratio measurements), which is a challenge associated with most sample preparation procedures. It was mainly in the 1990s when Lobinski and other speciation experts stressed the need to use the combination of elemental and molecular MS and other complementary techniques for elemental species identification over previously reported retention time identification by ICP-MS detection. Today, speciation scientists are more aware of the potential and challenges of this combined approach and, especially, of the power of accurate mass measurement and have, therefore, used it successfully in many applications of speciation analysis to healthcare. Relevant examples include the identification of multiple selenium metabolites of relevance to cancer research and nutrition in food/ supplements, cancer cell lines and biological fluids and tissues, the identification of organoarsenic species (e.g. arsenosugars and arsenolipids) in food and arsenosugars and methylated arsenic species in urine. The introduction of new concepts, technologies and needs in modern clinical chemistry, such as understanding the role of metalloproteins in health and disease or the impact of metallodrugs in disease diagnosis or treatment, has led to major progress in healthcare elemental speciation but also to an increased number of analytical challenges. The possibility of measuring metal-to-sulfur ratios using interference-reducing ICP-MS opened a new door to the quantification and characterisation of metalloproteins and Published in the special issue Speciation Analysis in Healthcare with Guest Editor Heidi Goenaga Infante.

Chronic arsenicosis in cattle with special reference to its metabolism in arsenic endemic village of Nadia district West Bengal India

Thirty Milch cattle were selected randomly from a village of Nadia district of West Bengal, India containing high arsenic in water and soil samples. Milk, feces and hair samples were collected to analyze arsenic status in animals. Water and straw samples were also estimated for arsenic. Milk products prepared from milk of cattle rearing in arsenic prone village were also collected to quantify total arsenic and speciation of arsenic in milk and feces samples were also carried out. It was observed that high amount of arsenic was present in milk, feces, hair of cattle and water and straw samples in arsenic prone village. Milk product also contained significant amount of arsenic than that of milk product of control village. Speciation study revealed arsenite fraction was mainly eliminated through milk, whereas organoarsenic species were mainly excreted through feces.

Arsenic speciation in municipal landfill leachate

Arsenic species in municipal landfill leachates (MLL) were investigated by HPLC–DRC–ICPMS and LC–ESI-MS/MS. Various arsenic species including arsenate (iAs V), arsenite (iAs III), monomethylarsonic acid (MMA V), dimethylarsinic acid (DMA V), as well as sulfur-containing organoarsenic species were detected. Two sulfur-containing arsenic species in a MLL were positively identified as dimethyldithioarsinic acid (DMDTA V) and dimethylmonothioarsinic acid (DMMTA V) by comparing their molecular ions, fragment patterns and sulfur/arsenic ratios with in-house synthesised thiol-organoarsenic compounds. The findings demonstrated the potential for transformation of DMA V to DMDTA V and DMMTA V in a DMA V-spiked MLL in a landfill leachate environment.

Organoarsenicals. Uptake, metabolism, and toxicity.

Arsenic is categorized by the WHO as the most significant environmental contaminant of drinking water due to the prevalence of geogenic contamination of groundwaters. Arsenic and the compounds which it forms are considered to be carcinogenic. The mechanism of toxicity and in particular of carcinogenicity of arsenic is still not well understood. The complexity originates from the fact that arsenic can form a rich variety of species, which show a wide variability in their toxicological behavior. The process of biomethylation was for many years regarded as a detoxification process; however, more recent research has indicated that the reverse is in fact the case. In this book chapter we give a summary of the current state of knowledge on the toxicities and toxicological mechanisms of organoarsenic species in order to evaluate the role and significance of these regarding their adverse effects on human health.

Bioaccessibility and Transport by Caco-2 Cells of Organoarsenical Species Present in Seafood

Organoarsenical standards and raw and cooked seafood (DORM-2, sole, and Greenland halibut) were subjected to in vitro gastrointestinal digestion to estimate arsenic bioaccessibility (maximum soluble concentration in gastrointestinal medium). The in vitro digestion did not modify the chemical form of the organoarsenic species standards. In seafood, bioaccessibility was 67.5-100% for arsenobetaine (AB), 30% for dimethylarsinic acid (DMA), 45% for tetramethylarsonium ion (TETRA), and >50% for trimethylarsine oxide (TMAO). Cooking induced no changes in bioaccessible contents. In addition, transport by Caco-2 cells, an intestinal epithelia model, was evaluated from organoarsenical standards and DORM-2. For standards, transport ranged from 1.7% for AB to 15.5% for TETRA. In DORM-2, transport was observed for only AB (12%), with far higher efficiency than in the case of the standard solution, thus illustrating the interest of using whole foods for studying bioavailability.

Distribution and Fate of Inorganic and Organic Arsenic Species in Landfill Leachates and Biogases

The arsenic release from landfills requires special attention both due to its potential toxicity and due to the increasing global municipal solid waste production. The determination of arsenic species in both leachates and biogases has been performed in this work to determine the fate of arsenic in landfills. Both inorganic and methylated arsenic species occur in leachates with concentrations varying from 0.1 to 80 microg As L(-1). These species are representative of the leachate arsenic composition, as the mean recovery obtained for the speciation analyses is 67% of the total arsenic determined in elementary analyses. In biogases, both methylated and ethylated volatile arsenic species have been identified and semiquantified (0-15 microg As m(-3)). The landfill monitoring has emphasized close relationships between the concentrations of mono-, di-, and tri-methylated arsenic compounds in leachates. A biomethylation pathway has thus been proposed as a source of these methylated compounds in the leachates from waste arsenic, which is supposed to be in major part under inorganic forms. In addition, peralkylation mechanisms of both biomethylation and bioethylation have been suggested to explain the occurrence of the identified volatile species. This combined speciation approach provides a qualitative and quantitative characterization of the potential emissions of arsenic from domestic waste disposal in landfills. This work highlights the possible formation of less harmful organoarsenic species in both leachates and biogases during the waste degradation process.

Genotoxicity induced by arsenic compounds in peripheral human lymphocytes analysed by cytokinesis-block micronucleus assay

This work focuses on the analysis of genotoxic effects on human peripheral lymphocytes exposed in vitro to different arsenic (As) compounds by means of the cytokinesis-block micronucleus assay. The study was carried out by challenging peripheral human lymphocytes with six As compounds in trivalent or pentavalent forms such as arsenite (As(III)) and arsenate (As(V)) and organoarsenic species such as monomethylarsonous acid (MMAs(III)), monomethylarsonic acid (MMAs(V)), dimethylarsinic acid (DMAs(V)) and trymethylarsine oxide (TMAO(V)). For As(III) and As(V) at concentrations of 4 and 32 microM, respectively, an increase of micronuclei (MN) frequency was found. MMAs(III) and MMAs(V) induced a statistically significant increase of MN frequency at the dose of 2 and 500 microM, respectively. For DMAs(V), no significant increase of MN was observed, although a decrease of the nuclear division index (NDI) was evident, indicating a cytotoxic effect. The genotoxic mechanism of action of MMAs(III) was further evaluated by means of fluorescence in situ hybridization analysis. Due to a higher percentage of centromere-positive MN, MMAs(III) showed a clear aneuploidogenic property. Finally, for TMAO(V) no genotoxicity was observed up to 1 mM. These results show how speciation is important in determining the genotoxic and cytotoxic effects of As compounds in human peripheral lymphocytes and support the emerging hypothesis that the induction of aneuploidy could be a mechanism by which As exerts its carcinogenic properties.

Mapping of arsenic species and identification of a novel arsenosugar in giant clams Tridacna maxima and Tridacna derasa using advanced mass spectrometric techniques

Environmental context. Arsenic is known to accumulate in various marine organisms. The high acute toxicity of inorganic arsenic species and the potential chronic toxicity of some organoarsenic species require detailed knowledge about the occurrence and metabolism of arsenic compounds in marine organisms. The application of advanced analytical techniques still allows, even after decades of arsenic speciation, the identification of novel species. In addition, comprehensive mapping of all arsenic species present in marine organisms may allow for a more detailed understanding of arsenic metabolism. Abstract. Because of their symbiotic microalgae, giant clams (Tridacna species) exhibit a unique arsenic metabolism, which has been shown in previous studies to involve a large number of arsenic species. This study demonstrates the application of liquid chromatography (HPLC) online with electrospray tandem mass spectrometry (ES-MS/MS) as well as inductively coupled plasma mass spectrometry (ICP-MS) for arsenic speciation analysis in giant clam extracts. Selected reaction monitoring (SRM) was used for sensitive and selective detection of a large number of arsenic species in a single chromatographic run. Novel aspects are the analysis of 10 tissue fractions from one clam and the analysis of kidney extracts both from T. maxima and T. derasa with the same method thus offering the possibility for direct comparisons. Moreover, HPLC-ES-MS/MS in the precursor ion scan mode and product ion scan mode allowed the identification of a novel sulfonated dimethylarsenosugar and the partial characterisation of another unknown arsenic species. The results indicate that most arsenic species are accumulated in the kidneys. However, arsenobetaine was found at similar contents in all analysed tissue fractions of one T. maxima clam.

Development of a liquid chromatography/electrospray selected reaction monitoring method for the determination of organoarsenic species in marine and freshwater samples

Cation- and anion-exchange high-performance liquid chromatography/electrospray selected reaction monitoring (HPLC/ES-SRM) methods were developed for the determination of 15 organoarsenic compounds in marine and freshwater samples. The results demonstrate that the developed HPLC/ES-SRM methods are powerful approaches for the identification of organoarsenic species in crude sample extracts. The detection limits, linearity as well as reproducibility for most of the species are comparable or even better than those measured by the HPLC/inductively coupled plasma mass spectrometry (ICPMS) technique. The qualitative analysis of the extracts shows that the developed methods allow for the identification of arsenicals which were not detectable by ICPMS. It was also demonstrated that the signal suppression caused by matrix effects means a significant limitation in the quantification of arsenicals by ES-SRM detection. This drawback is manifested especially in the case of the slightly retained species. The three sample-cleanup chromatographic methods including off-line size-exclusion, on-line reversed-phase and on-line oppositely charged ion-exchange approaches proved to be ineffective for separation of the signal-suppressive matrix from the analytes. The standard addition calibration seems to be a suitable solution for such problems.

Arsenic speciation in arsenic-rich Brazilian soils from gold mining sites under anaerobic incubation

Arsenic speciation in environmental samples is essential for studying toxicity, mobility and bio-transformation of As in aquatic and terrestrial environments. Although the inorganic species As(III) and As(V) have been considered dominant in soils and sediments, organisms are able to metabolize inorganic forms of arsenic into organo-arsenic compounds. Arsenosugars and methylated As compounds can be found in terrestrial organisms, but they generally occur only as minor constituents. We investigated the dynamics of arsenic species under anaerobic conditions in soils surrounding gold mining areas from Minas Gerais State, Brazil to elucidate the arsenic biogeochemical cycle and water contamination mechanisms. Surface soil samples were collected at those sites, namely Paracatu Formation, Banded Iron Formation and Riacho dos Machados Sequence, and incubated in CaCl2 2.5 mmol L(-1) suspensions under anaerobic conditions for 1, 28, 56 and 112 days. After that, suspensions were centrifuged and supernatants analyzed for soluble As species by IC-ICPMS and HPLC-ICPMS. Easily exchangeable As was mainly arsenite, except when reducible manganese was present. Arsenate was mainly responsible for the increase in soluble arsenic due to the reductive dissolution of either iron or manganese in samples from the Paracatu Formation and Riacho dos Machados Sequence. On the other hand, organic species of As dominated in samples from the Banded Iron Formation during anaerobic incubation. Results are contrary to the expectation that, in anaerobic environments, As release due to the reductive dissolution of Fe is followed by As(V) reduction to As(III). The occurrence of organo-arsenic species was also found to be significant to the dynamics of soluble arsenic, mainly in soils from the Banded Iron Formation (BIF), under our experimental conditions. In general, As(V) and organic As were the dominant species in solution, which is surprising under anaerobic conditions in terrestrial environments. The unexpected occurrence of organic species of As was attributed to enrollment of ternary organic complexes or living organisms such as algae or cyanobacteria. These findings are believed to be useful for remediation strategies in mine-affected regions, as the organic As species are in general considered to be less toxic than inorganic ones and even As(V) is considered less mobile and toxic than As(III).

Improved Arsenic Speciation Analysis for Extracts of Commercially Available Edible Marine Algae Using HPLC-ES-MS/MS

Their increasing commercial availability and their rather high total arsenic contents necessitate a more detailed arsenic speciation analysis of marine algal products. Compared to current HPLC-ICPMS methods, HPLC on-line with electrospray tandem mass spectrometry in the selected reaction monitoring mode (HPLC-ES-SRM) offers much higher detection selectivity with similarly high sensitivity for most known organoarsenic species. This study demonstrates the advantages of HPLC-ES-SRM for the detection of the main as well as trace arsenic species in extracts of 12 commercially available marine algal powders. The main focus was the unambiguous identification of the detected arsenic species. Four quality control tools were applied for this purpose, including matching chromatographic retention times, comparing SRM transition ratios, recording product ion spectra, and determining accurate masses. As a result, evidence was obtained for the presence of 19 organoarsenic species in the analyzed algal extracts. The method of standard addition was used for quantification. Estimated matrix effects on the analyte signal were similar for most of the investigated arsenic species in extracts of different types of brown algae. This allowed the comparison of the contents of the arsenic species present in the 12 algal extracts on the basis of normalized peak areas. A partial correlation of the arsenic speciation pattern with the algal family or algal order, respectively, was found.

Arsenic speciation in moso bamboo shoot — A terrestrial plant that contains organoarsenic species

Arsenic is predominantly found as an inorganic species in most terrestrial plants. However, we found that a significant proportion of organic arsenic was present in moso bamboo (Phyllostachys pubescens Mazel) shoot in a market survey of arsenic species in edible terrestrial plants. Moso bamboo shoots from different producing areas in China were collected for analysis to confirm the ubiquity of methylated arsenic species. The total arsenic concentrations of bamboo shoots were determined by hydride generation coupled atomic fluorescence spectrometry (HG-AFS), ranging from 27.7 to 94.0 microg/kg. Information about arsenic species was acquired from cold trap-hydride generation-atomic absorption spectrometry (CT-HG-AAS). Dimethylarsinic acid (DMA) was present in the amount of 13.9% to 44.9% of sum of the arsenic species in all these samples. Monomethylarsonic acid (MMA) and trimethylarsine oxide (TMAO) were also detected in certain samples in the range of 4.2-16.5% and 11.8-18.4%, respectively. In addition, bamboo shoots collected in winter were found to have more total arsenic and organic arsenic than those collected in spring. To investigate the source of the organic arsenic in moso bamboo shoots, arsenic species in the rhizosphere soils of the plants were examined. The absence of organic arsenic in soils would suggest the possibility of formation of methylated arsenic in the plants. In addition, studies of arsenic speciation in the peel and core of winter bamboo shoots showed that all the cores contained organic arsenic while no organic arsenic was detected in the peels. The study provides useful information for better understanding of the distribution of arsenic species in terrestrial plants.

Optimisation of an HPLC selected reaction monitoring electrospray tandem mass spectrometry method for the detection of 50 arsenic species

Selected reaction monitoring (SRM) electrospray tandem mass spectrometry online with HPLC is routinely applied for organic trace analysis, e.g. drug metabolites and pesticide residues. However, it has so far found only limited application for the characterisation of trace element species. This is of particular relevance for arsenic speciation analysis because the structural diversity of arsenic species requires high detection selectivity which cannot be achieved with the predominantly applied HPLC online with inductively coupled plasma mass spectrometry. For this reason we have studied the collision induced dissociation behaviour of 50 organoarsenic species to optimize the conditions for their detection using anion exchange HPLC online with electrospray triple quadrupole mass spectrometry operated in the SRM mode. The effect of quadrupole scan time on peak area reproducibility was studied for selected arsenic species. The possibility of “cross talk” occurring between subsequently monitored transitions was also investigated. For quality control purposes SRM transition ratios (peak area) were calculated from the two transitions monitored for each arsenic species (except for monomethylarsonic acid). Calibration experiments were performed for four arsenic species using three different mass spectrometric scanning methods: first a method monitoring all 50 species (99 SRM transitions) in rapid sequence throughout the chromatographic run (non-segmented), second a two-segment method monitoring all species, 32 species in the first time segment and 18 in the second time segment, and third a four-segment method monitoring only one species per time segment. Linear regression parameters and limits of detection were not significantly different for the three methods. Finally, the non-segmented method was applied for the identification of arsenic species in a Tridacna (giant clam) kidney extract. In addition, arsenic species were characterised in the kidney extract following reaction with hydrogen sulfide or after methylation.

Release of Arsenic to the Environment from CCA-Treated Wood. 2. Leaching and Speciation during Disposal

Wood treated with chromated copper arsenate (CCA) is primarily disposed within construction and demolition (C&D) debris landfills, with wood monofills and municipal solid waste (MSW) landfills as alternative disposal options. This study evaluated the extent and speciation of arsenic leaching from landfills containing CCA-treated wood. In control lysimeters where untreated wood was used, dimethylarsinic acid (DMAA) represented the major arsenic species. The dominant arsenic species differed in the lysimeters containing CCA-treated wood, with As(V) greatest in the monofill and C&D lysimeters and As(III) greatest in the MSW lysimeters. In CCA-containing lysimeters, the organoarsenic species monomethylarsonic acid (MMAA) and DMAAwere virtually absent in the monofill lysimeter and observed in the C&D and MSW lysimeters. Overall arsenic leaching rate varied for the wood monofill (0.69% per meter of water added), C&D (0.36% per m), and MSW (0.84% per m) lysimeters. Utilizing these rates with annual disposal data, a mathematical model was developed to quantify arsenic leaching from CCA-treated wood disposed to Florida landfills. Model findings showed between 20 and 50 t of arsenic (depending on lysimeter type) had leached prior to 2000 with an expected increase between 350 and 830 t by 2040. Groundwater analysis from 21 Florida C&D landfills suspected of accepting CCA-treated wood showed that groundwater at 3 landfills was characterized by elevated arsenic concentrations with only 1 showing impacts from the C&D waste. The slow release of arsenic from disposed treated wood may account for the lack of significant impact to groundwater near most C&D facilities at this time. However, greater impacts are anticipated in the future given that the maximum releases of arsenic are expected by the year 2100.

Release of Arsenic to the Environment from CCA-Treated Wood. 1. Leaching and Speciation during Service

Insufficient information exists about the speciation of arsenic leaching from in-service chromated copper arsenate (CCA)-treated products and the overall impact to soils and groundwater. To address this issue, two decks were constructed, one from CCA-treated wood and the other from untreated wood. Both decks were placed in the open environment where they were impacted by rainfall. Over a one-year period, rainwater runoff from the decks and rainwater infiltrating through 0.7 m of sand below the decks was collected and analyzed for arsenic species by HPLC-ICP-MS. The average arsenic concentration in the runoff of the untreated deck was 2-3 microg/L, whereas from the CCA-treated deck it was 600 microg/L. Both inorganic As(III) and As(V) were detected in the runoff from both decks, with inorganic As(V) predominating. No detectable levels of organoarsenic species were observed. The total arsenic concentration in the infiltrated water of the treated deck had risen from a background concentration of 3 microg/L to a concentration of 18 microg/L at the end of the study. Data from the deck study were combined with annual CCA-treated wood production statistics to develop a mass balance model to estimate the extent of arsenic leaching from in-service CCA-treated wood structures to Florida soils. Results showed that during the year 2000, of the 28 000 t of arsenic imported into the state and utilized for in-service CCA-treated wood products, approximately 4600 t had already leached. Future projections suggest that an additional 11,000 t of arsenic will leach during in-service use within the next 40 years.

Transformation of Organoarsenical Species by the Microflora of Freshwater Crayfish

A study of the transformation of arsenic species by the microflora of the freshwater crayfish Procambarus clarkii was carried out. The study of the degradation of AB (arsenobetaine) was performed in aerobic conditions in two culture media (tryptic soy broth and saline medium) at two temperatures (30 and 8 degrees C). The microflora transformed AB into TMAO (trimethylarsine oxide), DMA (dimethylarsinate), MA (methylarsonate), and an unidentified compound (U1). The quickest transformations were carried out by microflora from hepatopancreas incubated in saline medium at 30 degrees C. The individualized study of other arsenic species [AC (arsenocholine), TETRA (tetramethylarsonium ion), TMAO, DMA, and MA] was also performed in saline medium. The only transformation observed was of AC into AB. The bacteria possibly responsible for AB degradation were isolated, identified by phenotypic and genotypic methods, and individually assayed for AB transformation. Only isolates allocated to the species Pseudomonas putida were able to metabolize AB.

Organoarsenical Species Contents in Cooked Seafood

The organoarsenical species arsenobetaine (AB), arsenocholine (AC), tetramethylarsonium ion (TMA+), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) were determined in 64 cooked seafood products (fish, bivalves, squid, crustaceans) included in a Total Diet Study carried out in the Basque Country (Spain). For cooking, various treatments were employed (grilling, roasting, baking, stewing, boiling, steaming, microwaving). The results obtained show that in cooked seafood AB is the major species, followed by DMA and TMA+. AC and MMA are minor species. The results in cooked seafood were compared with the arsenic species contents obtained for the same product raw. After cooking there was an increase in DMA for sardines and bivalves and an increase or appearance of TMA+ for meagrim, anchovy, Atlantic horse mackerel, and sardine. The data provided add to the very scant information available about organoarsenical species contents in cooked seafood.