Total Arsenic Levels Research Articles

Toxic effect of arsenite on the expression of liver multidrug resistance-associated protein 2 in rat

To investigate the role of multidrug resistance-associated protein 2 (MRP2) in the hepatic cell membrane of rats. Thirty healthy Wistar rats were divided randomly into six groups based on time of administration (2 w, 4 w, 6 w) of 20 mg/kg of sodium arsenite, and their corresponding control groups. Animals were administered every other day. Arsenic content in blood and bile were detected by atomic absorption spectroscopy (AAS), and the expression of MRP2 in the membrane of hepatocyte by Western blotting was determined. Total arsenic levels (including organic arsenic and inorganic arsenic) in blood and bile were significantly higher than control groups (P < 0.05) at all three different time points, especially in 2 w and 4 w group (16.8 and 13.8 fold greater than that in control). The expression of MRP2 increased 36.61%, 32.36%, 12.73% more respectively in 2 w, 4 w, 6 w groups than those in control groups (P < 0.05). The expression of MRP2 was correlated with total arsenic content in bile (r = 0.713, P < 0.05). Bile is one of the major routes for the excretion of arsenite and its metabolites, and the overexpression of MRP2 may play an important role in the bile excretion of them at early stage.

Arsenic levels in the soils and macrophytes of the ‘Entremuros’ after the Aznalcóllar mine spill

In April 1998, a holding lagoon containing pyrite ore processing waste rich in arsenic, failed and released 5–6 million m 3 of highly polluting sludge and acidic water. Over 2700 ha of the internationally important Doñana National and Natural Parks were contaminated. The area of Natural Park to sustain the greatest impact was known as the Entremuros. This paper presents 0–5 cm soil monitoring data from the Entremuros, from sampling campaigns 6 and 18 months after the disaster; as well as macrophyte root, rhizome and stem data from samples taken 18 months after the spill. Results show a clear, decreasing, north–south arsenic soil pollution trend, both 6 and 18 months after the spill, and suggest a small reduction in total soil arsenic levels occurred over time; although a significant increase in extractable arsenic is also noted. The two macrophytes ( Typha dominguensis and Scirpus maritimus) studied herein are not accumulating arsenic in stem parts, however, accumulation of arsenic on iron plaque on the roots of these plants may be occurring. Further work is recommended in order to determine the ecotoxicological significance of this process in relation to the avian food-chains of Doñana, and elsewhere.

Determination of total arsenic levels by hydride generation atomic absorption spectrometry in foods from south-east Spain: estimation of daily dietary intake

The total concentration of arsenic in different foods from south-east Spain was determined by hydride generation atomic absorption spectrometry. Mineralization was carried out with an HNO3-HClO4 mixture in a thermostated sand bath. Arsenic determination was performed by the standard addition method. Analyses of NIST and CBR-CEC reference materials demonstrated the reliability and accuracy of the technique. The highest arsenic levels were found in seafood, cereals, meat and meat by-products. In meat and meat by-products, the total arsenic measured in meat was significantly higher than that in sausages (p<0.05). In cereals, arsenic concentrations in corn and white rice samples were significantly higher (p<0.01) than those measured in wheat by-products. Mean arsenic concentrations in cheese were statistically lower than those in other dairy products (p<0.01). New data have been provided on the total arsenic content of a variety of foods in Spain, which is important for making exposure estimates. The estimated daily intake of total arsenic in the Spanish diet was 221 μg As day−1.

Arsenic speciation and reactivity in poultry litter.

Recent U.S. government action to lower the maximum concentration levels (MCL) of total arsenic (As) (10 ppb) in drinking water has raised serious concerns about the agricultural use of As-containing biosolids such as poultry litter (PL). In this study, solid-state chemical speciation, desorbability, and total levels of As in PL and long-term amended soils were investigated using novel synchrotron-based probing techniques (microfocused (micro) synchrotron X-ray fluorescence (SXRF) and micro-X-ray absorption near-edge structure (XANES) spectroscopies) coupled with chemical digestion and batch experiments. The total As levels in the PL were as high as approximately 50 mg kg(-1), and As(II/III and V) was always concentrated in abundant needle-shaped microscopic particles (approximately 20 microm x 850 microm) associated with Ca, Cu, and Fe and to a lesser extent with S, Cl, and Zn. Post-edge XANES features of litter particles are dissimilar to those of the organo-As(V) compound in poultry feed (i.e., roxarsone), suggesting possible degradation/transformation of roxarsone in the litter and/or in poultry digestive tracts. The extent of As desorption from the litter increased with increasing time and pH from 4.5 to 7, but at most 15% of the total As was released after 5 d at pH 7, indicating the presence of insoluble phases and/or strongly retained soluble compounds. No significant As accumulation (< 15 mg kg(-1)) was found in long-term PL-amended agricultural surface soils. This suggests that As in the PL may have undergone surface and subsurface transport processes. Our research results raise concerns about long-term PL amendment effects on As contamination in surrounding soil-water environments.

Arsenic species contents at aquaculture farm and in farmed mouthbreeder ( Oreochromis mossambicus) in blackfoot disease hyperendemic areas

A study was conducted to measure the arsenic species in farmed mouthbreeder ( Oreochromis mossambicus) and culture ponds in water in blackfoot disease (BFD) hyperendemic areas in Taiwan. The relationships between arsenic species of aquaculture ponds and farmed fish were also explored. Biota samples were extracted with methanol/water (1/1, v/v) using a Soxhlet extraction apparatus. The concentrations of arsenite As (III), arsenate As (V), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) of extracts were measured by high-performance liquid chromatography (HPLC) linked to a hydride generator and atomic absorption spectrometry (HG-AAS). Moreover, arsenobetaine (AB) was analyzed by HPLC linked to ultra violet (UV) and HG-AAS. Concentrations of arsenic species were determined in 68 mouthbreeder ( O. mossambicus) samples and 21 culture ponds from Putai and Yichu Townships of Chiayi County and Hsuehchia and Peimen Townships of Tainan County. The mean arsenic levels of culture ponds in Putai, Yichu, Hsuehchia, and Peimen were 75.8, 15.1, 14.4, and 221.0 μg/l, respectively. The water of culture ponds was dominated by As (V). The inorganic arsenic percentage of fish (7.4%) was higher than that reported by other seafood surveys. Except for the MMA and As (III) levels, As (V), DMA, AB, and total arsenic levels in fish significantly increased with inorganic and total arsenic concentrations of the pond water. Inorganic arsenic species are more toxic than methyl arsenic species. Therefore the effect of inorganic arsenic species might result in a greater number of adverse health effects to the general public. It is of importance to evaluate the inorganic arsenic levels of farmed seafood in arsenic-contaminated areas.

Geogenic arsenic in groundwaters from Terai Alluvial Plain of Nepal

The origin and mobility of arsenic (As) in the groundwater environment has received serious attention in recent years. Recent studies have reported naturally occurring As in groundwaters of the Terai Alluvial Plains (TAP) in southern Nepal, where groundwater exploitation has increased since the 1960s. The source of As in TAP is geogenic and leached primarily due to weathering of As bearing rocks and sediments in the Himalayas. In the present study, we have investigated the groundwater chemistry in the central part of the TAP in Nawalparasi district. TAP groundwaters are near-neutral to alkaline, with predominantly reducing character and high HCO 3 - , low SO 4 2- and NO 3 - concentrations. Elevated HCO 3 - levels possibly result due to the oxidation of organic matter, low SO 4 2- levels reflect sulfate reduction. Elevated NH 4 + concentrations in these groundwaters suggest dissimilatory nitrate reduction in the aquifers. Total arsenic (As tot ) levels in groundwater varied from 1.7 μg/L to as high as 404 μg/L with dominance of As(III) species and elevated levels of dissolved Fe and Mn. Arsenic is mobilized in groundwaters as a result of desorption of As-oxyanions adsorbed onto Fe- and Mn-oxides as well as reductive dissolution of these surface reactive phases from the sediments along with release of As in anoxic groundwaters.

Sequential hydride generation/pneumatic nebulisation inductively coupled plasma mass spectrometry for the fractionation of arsenic and selenium species

The toxicity of certain elements is known to be related to their organic substituents and/or oxidation states. As such, total elemental determinations do not always yield sufficient information for accurate risk assessments and therefore speciation or fractionation data are required. In order to obtain fractionation data for trace levels of arsenic and selenium, a novel sequential pneumatic nebulisation (PN)/hydride generation (HG) inductively coupled plasma mass spectrometry (ICP-MS) method was developed. The method offers the advantage of sample introduction via either PN or HG by simply rotating a 4-way switching valve while the system is in operation. In PN mode, the liquid sample is aspirated into ICP, allowing for the determination of the total amount of each element, whilst in HG mode only the arsenic and selenium species that form volatile hydrides are determined. Conveniently, in the case of arsenic, this allows for differentiation between the four most toxic arsenic species (arsenate, arsenite, monomethylarsonic acid and dimethylarsinic acid), which form volatile hydrides, and the virtually non-toxic forms (arsenobetaine, arsenosugars, etc.), which do not. This allows for the rapid estimation of the amounts of toxic and non-toxic arsenic species present in a sample. For arsenic, the technique gave detection limits of 36 ng l −1 in PN mode and 1 ng l −1 in HG mode. For selenium, detection limits of 150 ng l −1 were achieved in PN mode and 220 ng l −1 in HG mode. The technique also gave good long- and short-term stabilities of under 6% RSD for both elements. A variety of samples, including water and urine standard reference materials, were analysed in both modes, and the precision and accuracy of the results for total arsenic and selenium levels were assessed. Using the technique in both modes also allowed for the fractionation of As and Se species into their volatile hydride-forming and non-hydride-forming species. This was particularly informative, with respect to As species present, in the case of a kelp powder extract. Digested tobacco samples were only analysed for their total As levels, in which case results obtained via both sample introduction modes showed good agreement.

Risk assessment of chromium and arsenic in date palm leaves used as livestock feed

Appreciable levels of total chromium (Cr) and arsenic (As) were found (by emission spectroscopy) in date palm leaves, which form a significant ingredient in livestock feed. The levels in the fruit were considered safe for human consumption. Our work involved evaluation of the distribution of these elements in the leaves during the developmental stages of the fruiting season. Thirty-six leaf specimens of the Fard cultivar were collected 9, 15 and 20 weeks, respectively, after pollination and subjected to a standard digestion procedure. Sample masses of typically 1 g (dry weight) were prepared in 25 ml dilute acid solution and investigated for trace levels of Cr and As by ICP-AES. Eleven soil samples collected at random during the growth stages were subjected to a similar digestion procedure and analysis. According to the literature, the permissible mean levels of Cr and As in plants are 200 and 80 ng/g (dry weight), respectively. We used these values as our guideline to assess the “risk” levels in our samples of interest. In the case of Cr, about 45% of the specimens possessed levels between 250 and 700 ng/g, while a significant number produced levels between 1000 and 5000 ng/g. With regard to As, about 70% of the samples were above the documented permissible mean value. As a result of the unusually high Cr concentrations in some cases, the feasibility of Cr “accumulation” in the leaves was examined. Insects and other organisms subsist on the leaves and an added concern was the accumulation of these elements in the food chain. The study formed an interesting contribution to environmental research, and the impact of our assessment on the environment is discussed.

Total and toxic arsenic levels in north sea fish.

Levels of arsenic contamination in muscle and liver tissue of 25 sea fish and 4 shellfish species from the North Sea were determined. Analyses were done by both ICP-MS and HG-AFS to distinguish between nontoxic and toxic fractions of As. Highest total As concentrations were found in lemon sole, dogfish, ray, and witch. Average total As concentrations in these fish species were higher than 20 mg kg(-1) WW. The same species as well as the other flatfishes contained the highest amounts of toxic As (> 0.1 mg kg(-1) WW). Toxic fractions (AsTox/AsT%) above 2% were found in the following six species: seabass, ling, john dory, pouting, dab, and brill. No preferential concentration in the liver compared to the muscle was observed. In a worst-case scenario (when fish has been dried or smoked and the toxic As level is high; for example 0.5 mg kg(-1) WW), the As content of North Sea marine food may reach harmful levels. A normalization reflecting the toxic potential of sea fish was made. Shark and ray and most flatfish species have positive (high) normalized AsTox values.By ANOVA testing we compared the individual AsT concentrations of samples of the same species (intraspecies variability). Significant differences for some fish species were observed; significantly higher AsT concentrations were found in dogfish from the French coast versus the western North Sea and in common sole from the Bay of the Seine, in the north of France, versus the western North Sea.

Distribution of arsenic species in the freshwater crustacean Procambarus clarkii

AbstractThe concentrations of total arsenic and arsenic species in the complete organism of the crayfish Procambarus clarkii and its various parts (hepatopancreas, tail, and remaining parts) were analyzed in order to discover the distribution of arsenic and its species. With this information it will be possible to establish where the chemical forms of this metalloid tend to accumulate and what risks may derive from the contents and species present in the edible parts of this crustacean. The total arsenic content in the complete organism and in the various parts analyzed ranged from 2.5 to 12 µg g−1 dry mass (DM), with inorganic arsenic representing 18 to 34% of total arsenic. The arsenical composition varied according to the part of the crayfish considered. The hepatopancreas had the highest levels of total arsenic (9.2–12 µg g−1 DM) and inorganic arsenic (2.7–3.2 µg g−1 DM). The tail (edible part) had the lowest levels of both total arsenic (2.5–2.6 µg g−1 DM) and inorganic arsenic (0.46–0.64 µg g−1 DM). The predominant organoarsenical species were the dimethylarsinoylribosides: glycerol riboside in the hepatopancreas, sulfate riboside in the tail, and sulfonate and phosphate ribosides in the remaining parts. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Determination of total arsenic, inorganic and organic arsenic species in wine

Forty-five wine samples from the south of Spain of different alcoholic strength were analysed for total arsenic and its inorganic [As(III), As(V)] and organic (monomethylarsonic acid [MMAA], dimethylarsinic acid [DMAA]) species. The As levels of the wine samples ranged from 2.1 to 14.6 µg l-1. The possible effect of the alcoholic fermentation process on the levels of the total arsenic and arsenical species was studied. The average total arsenic levels for the different samples were very similar, without significant differences between all types of wines. In table wines and sherry, the percentages of total inorganic arsenic were 18.6 and 15.6%, with DMAA or MMAA being the predominant species, respectively. In most samples, DMAA was the most abundant species, but the total inorganic aresenic fraction was considerable, representing 25.4% of the total concentration of the element. The estimated daily intakes of total arsenic and total inorganic arsenic for average Spanish consumers were 0.78 and 0.15 µg/person day-1, respectively. The results suggest that the consumption of these types of wines makes no significant contribution to the total and inorganic arsenic intake for normal drinkers. However, wine consumption contributes a higher arsenic intake than through consumption of beers and sherry brandies.

Anthropogenic and natural levels of arsenic in PM10 in Central and Northern Chile

A few copper and gold smelters in Chile are behind a large fraction of global arsenic emissions, raising concerns for increased concentrations of arsenic in PM10 in Central and Northern Chile. This concern is amplified by the fact that Northern Chile soils and rivers in general are characterized by a high arsenic content. A monitoring and modeling study has been performed to quantify the regional impact of the smelter emissions. Measured atmospheric arsenic concentrations from 2.4 to 30.7 ng m −3 were found at seven rural stations, located tens to hundreds of kilometers away from the nearest smelter. Analyses of topsoil and subsoil samples taken from PM10 monitoring stations revealed levels up to 291 mg kg −1, the highest values found in the northern Atacama desert in Chile. An absolute principal component analysis of selected trace elements in PM10 shows that the regional impact of anthropogenic smelter emissions on airborne arsenic concentrations is more important than the effect of soil dust resuspension. The dominance of the smelter emissions is larger in Central Chile than in the northern parts. The impact of resuspended soil dust on airborne arsenic levels in rural areas was estimated not to exceed 5 ng m −3. The model calculations support the dominant role of anthropogenic emissions and give spatial and temporal variations in atmospheric concentrations consistent with the monitored levels at five of the seven stations. At two of the northernmost stations indications were found of unidentified sources other than the smelters and the resuspended soil dust, contributing to about 5 ng m −3 of total arsenic levels. The study confirms that a strong control or elimination of arsenic emissions from the smelters would lead to arsenic in PM10 levels in Northern and Central Chile comparable to non-polluted areas in other countries.

The Effect of Dietary 3-Nitro-4-Hydroxyphenylarsonic Acid (Roxarsone) on the Total Arsenic Level in Broiler Excreta and Broiler Litter

Broiler chickens are routinely fed diets containing the growth promotant 3-nitro-4-hydroxyphenylarsonic acid (roxarsone; ROX). Four trials were conducted to determine the amount of arsenic present in broiler excreta and broiler litter when broilers were fed a diet containing ROX. Two experimental diets were utilized in all four experiments: the control diet (CON) that contained no added ROX and the ROX diet that contained 45.4 g of ROX per ton. The CON and ROX diets were fed from 1 d of age until 42 d of age. From 42 to 47 d of age, both treatments received a withdrawal diet that contained no ROX. Weekly fecal samples were taken during Experiment 1. In Experiments 2, 3, and 4, litter samples were collected prior to each chick placement and at the end of each growout. All fecal and litter samples were analyzed for total arsenic content. In Trial 1, the total arsenic level in the feces of birds receiving the ROX diet increased from 1 to 4 wk; the total arsenic level decreased from 4 to 6 wk, and continued to decrease through the withdrawal period (42 to 47 d). In addition, the ROX birds exhibited a greater level of total arsenic in the feces than the CON birds during each week of Trial 1. The total arsenic level in the feces of the birds receiving the CON diet remained constant throughout Trial 1. In Trials 2, 3, and 4, the total arsenic level in ROX built-up litter did not exhibit a continuous increase with multiple growouts and remained constant in the CON built-up litter.

Urinary transforming growth factor-alpha in individuals exposed to arsenic in drinking water in Bangladesh

Recent evidence suggests that the development of skin lesions from arsenic exposure may be mediated by increases in the expression of various growth factors, including transforming growth factor-alpha (TGFα). To investigate this association in humans, levels of total urinary arsenic and urinary TGFα were determined in 41 individuals with and without arsenic-associated skin lesions from Bangladesh who have chronic exposure to arsenic in their drinking water. After adjusting for age and sex, total urinary arsenic was found to be correlated with urinary TGFα (R 2 = 0.37; p < 0.0001), particularly in those individuals with arsenic-associated skin lesions (R 2 = 0.70; p < 0.0001). Stratification of the cohort into quartiles based on urinary TGFα levels demonstrated a trend of increasing odds ratios for the presence of arsenic-associated skin lesions with increasing urinary TGFα, although this was not significant (p = 0.15). These results suggest that urinary TGFα may be a useful biomarker for the epidermal effects of arsenic exposure.

Organic and inorganic arsenic and lead in fish from the South Adriatic Sea, Italy

Total, organic and inorganic arsenic and lead were measured from the muscle of different kinds of fish: skate (Raje spp.), hake (Merluccius merluccius) and blue whiting (Micromesistius poutassou), caught in the South Adriatic Sea (South Italy) in the period June–August 1995. The highest levels of total arsenic were found in skate (Raje spp.) whose values ranged from 14.4 to 61.5mg/kg ww, followed by blue whiting (M. poutassou) and hake (M. merluccius) that showed lower levels ranging from 8.5 to 21.5mg/kg ww and from 5.9 to 16.1mg/kg ww, respectively. In all the species examined most of this element was present as organic compounds while inorganic arsenic was only a very modest percentage (0.47–3.5%) of the total arsenic present. Lead in all species analysed was at small concentrations with mean values ranging from 0.12 to 0.15mg/kg ww. According to the rules in force in Italy no samples showed concentrations of lead exceeding the peak value of 2 mg/kg.

Total and inorganic arsenic in fresh and processed fish products.

Total arsenic and inorganic arsenic contents were determined in 153 samples of seafood products consumed in the Basque Country (Spain): fish (white fish and blue fish), mollusks, crustaceans, and preserved fish. White fish presented higher levels of total arsenic and lower levels of inorganic arsenic than the blue fish, indicating possible differences in the metabolization of inorganic arsenic. For total arsenic, 66% of the samples exceeded the maximum permitted level by the strictest international legislation in seafood products [1 microg g(-)(1), wet weight (ww)]. The levels of inorganic arsenic were considerably lower than the maximum authorized in New Zealand (2 microg g(-)(1), ww), the only country with legislation for inorganic arsenic in fish and fish products. It is recommended that legislation based on levels of inorganic arsenic should be established.

Total arsenic, lead, and cadmium levels in vegetables cultivated at the Andean villages of northern Chile

Various vegetables (broad beans, corn, potato, alfalfa and onion) were sampled in northern Chile, Antofagasta Region. They are the basis of human nutrition in this region and of great relevance to human health. This region is characterized by volcanic events (eruptions, thermal springs, etc.). Most of the vegetables cultivated in this area enter the local markets for a population of approximately 4000 people, whose ancestors were mainly atacameños and quechuas (local indigenous people). The cadmium and lead in these foods was determined by differential pulse anodic stripping voltammetry (DPASV). Results indicate that the highest concentration of Pb and Cd are in the potato skin, while the edible part of the potatoes contained a lower concentration of these metals. The INAA analyses of As in the vegetables from Socaire and Talabre, two towns located close to active volcanoes (e.g. Lascar), show a very high As content: 1850 μg/kg in corn (Socaire) and 860 μg/kg in potatoes (+skin) (Talabre). These values exceed the National Standard for arsenic (500 μg/kg) by approximately 400% and 180%, respectively. In general, the data show a concentration of Pb greater than Cd with the potential for some vegetables to accumulate heavy metals. The values, expressed in fresh weight, vary from 0.2 to 40 μg/g for Cd and from 0.6 to 94 μg/g for Pb. These concentration intervals, except that of arsenic, are within the recommended standards in the Food Sanitary Regulation (Decree 977), which, expressed as fresh weight, must be equal to or smaller than 500 μg/kg for Pb. There is no legal standard for Cd.

Arsenic species in terrestrial fungi and lichens from Yellowknife, NWT, Canada

Levels of total arsenic and arsenic species were determined in fungi collected from Yellowknife, NWT, Canada, an area that has been affected by past mining activities and elevated arsenic levels. Lichens (belonging to Cladonia and Cladina genera), as well as the mushrooms Coprinus comatus, Paxillus involutus, Psathyrella candolleana and Leccinum scabrum, were studied for the first time. Most of the fungi contained elevated arsenic levels with respect to data found in the literature for background levels. Minor amounts of arsenobetaine were found in all lichen samples. The major water-soluble arsenic species in the fungi were inorganic arsenic for lichens and Psathyrella candolleana, arsenobetaine for Lycoperdon pyriforme and Coprinus comatus, and dimethylarsenate for Paxillus involutus and Leccinum scabrum. A large proportion of water-soluble arsenic in Paxillus involutus occurred as an unknown compound, which did not co-chromatograph with any of the available standard arsenic compounds. Low proportions of water-soluble arsenic species (made evident by low extraction efficiencies) were observed in the majority of fungi studied. Arsenic that is not extracted may be bound to lipids, cell components or proteins, or might exist on the surface of the fungus as minerals. Copyright © 2000 John Wiley & Sons, Ltd.

SYSTEMIC INDICATORS OF INORGANIC ARSENIC TOXICITY IN FOUR ANIMAL SPECIES

The effect of arsenic compounds depends on the chemical form and is specific for certain organs. The lack of specific biological indicators for the effects of each arsenic species makes it difficult to differentiate their toxicity. Five prospective biological indicators of system ic toxicity were examined at time points ranging from 15 m in to 24 h using male Sprague-Dawley rats, B6C3F1 mice, Golden-Syrian hamsters, and Hartley guinea pigs, following intraperitoneal dosing with 0.1 and 1 mg/kg sodium arsenite. Rats and mice were also dosed with 1 mg/kg sodium arsenate. Total blood arsenic levels were determined in all animal species to show that exposure occurred and as an index of the severity of the change is an indicator of toxicity. Total blood arsenic levels were increased in all animal species. This increase was dose, arsenic species, and animal dependent. Renal pyruvate dehydrogenase activity was significantly decreased at early time points in mice, hamsters, and guinea pigs, and at later time points in rats dosed with arsenite. Rats and mice dosed with arsenate also exhibited PDH decrease at early time points. Blood hematocrit and glucose were increased in the rat and guinea pig, respectively, after arsenite administration. Creatinine and urea nitrogen were found to be unresponsive to arsenic in most animal species. Data suggested that the mouse and secondly the hamster appear to be the most appropriate animal models for the study of acute arsenic toxicity. the acute toxicity of DMA is lower than that of the inorganic (Marafante et al., 1985). Each of these arsenic species has commercially and each has its own toxicity. Assigning toxic a particular species has been complicated by the finding that can, in some cases, metabolize one arsenic species to other et al., 1999). Environmental inorganic arsenic compounds metabolized, sometimes to other toxic intermediates (Cullen et Exposure to gallium arsenide (Webb et al., 1986) and exposure (Fowler & Weissberg, 1974) lead to pulmonary and blood toxicity, The arsenic species that induce toxicity in either case are not known. The development of biological indicators that differentiate As(III), As(V), and AsH3 toxicity could make it possible to the mechanisms of toxicity of some arsenic compounds. An indicator of arsenic exposure would show significant upon very-low-dose exposure and would respond quantitatively manner to each different chemical species of arsenic.

Total and inorganic arsenic in the fauna of the Guadalquivir estuary: environmental and human health implications

To evaluate the impact on fauna of the release of toxic waste from the tailings dam operated by the Boliden Apirsa S.L company at Aznalcóllar, Seville (Spain) a study was carried out of total and inorganic arsenic contents in 164 samples from six different estuary species, including molluscs, crustaceans and fish, collected at six sampling stations distributed along the estuary and mouth of the River Guadalquivir. The contents found, expressed in micrograms per gram wet weight, were as follows. Total arsenic: Crassostrea angulata — giant cupped oyster (2.44±0.45); Scrobicularia plana — peppery furrow (2.50±0.73); Palaemon longirostris — delta prawn (1.33±0.54); Uca tangeri — AfroEuropean fiddler crab (1.76±0.08); Melicertus kerathurus — shrimp (3.60±1.92); and Liza ramada — mullet (0.65±0.38). Inorganic arsenic: C. angulata (0.09±0.02); S. plana (0.38±0.23); P. longirostris (0.04±0.01); U. tangeri (0.22±0.03); M. kerathurus (0.03±0.01); and L. ramada (0.03±0.03). The levels of total As are comparable to those obtained by other authors. With respect to inorganic arsenic, only S. plana and U. tangeri present high levels of inorganic arsenic. This may be due to the fact that these organisms live in estuary sediments, reservoirs of inorganic arsenic, and ingest particles of sediments during feeding. Because of the lack of information for this area concerning previous levels of total and inorganic arsenic in the species analysed, it was not possible to establish the impact on the fauna of the River Guadalquivir estuary of the toxic spill resulting from the failure of the mine tailings dam at Aznalcóllar. With respect to the implications to human health as a result of consumption of species from the Guadalquivir estuary, only with the species Scrobicularia plana, as a high consumption of this mollusc might, in some cases, exceed the maximum tolerable intake for inorganic arsenic indicated by the FAO/WHO. Consumption of the liver of L. ramada does not appear to present problems to human health.