Arsenic Speciation in the Environment (Foods + Ingested Particles) Objectives being InvestigatedFurther to the successful completion of our study that measured the arsenic and chromium levels on children s hands after playing in playgrounds, this study will extend to measure biomarkers of exposure. Chromium and arsenic speciation in saliva and urine samples from the participating children will be determined and will be used to assess children s overall exposure to arsenic and chromium. To address some concerns over arsenic in game meat and traditional foods of the First Nations, moose and deer meat as well as cattail plant samples collected from First Nations communities in Northern Alberta will be studied for arsenic speciation. The chromatography and mass spectrometry techniques that have been developed during the previous period will be applied to the characterization and quantitation of arsenic species in these food samples. The skin and starchy tuber of cattail plants will be analyzed separately because our preliminary results have shown that elevated arsenic levels are found to be localized on the surface (skin) and fine roots of cattail. This separate analysis is important because it is the starchy tuber that is usually consumed. The speciation techniques will further be adapted and applied to studies of vanadium speciation in oilsands and processing by-products. Release of relatively high levels of vanadium from oilsands is a potential environmental concern that requires attention. Study/Sampling Design(a) Initially, soil/sand samples were obtained from eight Edmonton playgrounds containing wood treated with chromated copper arsenate (CCA) and another eight playgrounds that did not contain CCA-treated wood. Hand-washing samples were then obtained from 66 children who played in the eight playgrounds containing CCA and 64 children who played in the other eight playgrounds that did not contain CCA-treated wood. We have recently collected urine and saliva samples from children following playing in the CCA and non-CCA playgrounds. Speciation analysis of arsenic and chromium in children s hand washing, urine, and saliva samples provides an assessment of children s exposure to arsenic and chromium.

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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.

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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.

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.

Both intensity and type of habitat management in grasslands and heathlands affect spider communities. With high intensity management, spider communities often lack diversity and are dominated by a few r-selected species af®liated with bare ground. Low intensity management produces more complex communities introducing more niches for aerial web spinners and climbing spiders. The preferred management will be site-dependent and may not be appropriate for all spiders in all situations, particularly for some rare or threatened species. Providing natural cover is recommended when using extreme forms of management or intensive grazing (particularly by sheep). In extreme cases, or where trampling is heavy, the litter layer should be conserved. We advocate research and survey before and after major management implementation. Habitat management for spiders should not be considered alone, but integrated into a holistic plan. Management for spiders may con¯ict with rare plant conservation and small reserves should examine the viability of providing two contrasting regimes.