141 resultados para Arsenic in the body


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Irrigation with arsenic contaminated groundwater in the Bengal Delta may lead to As accumulation in the soil and rice grain. The dynamics of As concentration and speciation in paddy fields during dry season (boro) rice cultivation were investigated at 4 sites in Bangladesh and West Bengal, India. Three sites which were irrigated with high As groundwater had elevated As concentrations in the soils, showing a significant gradient from the irrigation inlet across the field. Arsenic concentration and speciation in soil pore water varied temporally and spatially; higher As concentrations were associated with an increasing percentage of arsenite, indicating a reductive mobilization. Concentrations of As in rice grain varied by 2-7 fold within individual fields and were poorly related with the soil As concentration. A field site employing alternating flooded-dry irrigation produced the lowest range of grain As concentration, suggesting a lower soil As availability caused by periodic aerobic conditions.

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In April 1998, a holding lagoon containing pyrite ore processing waste, failed and released 5-6 million m3 of highly polluting sludge and acidic water. Over 2650 ha of the internationally important Doñana Natural Park became contaminated, along with <100 ha of the more pristine Doñana National Park. In order to assess the affect of the spill on waterfowl from Doñana, bone and liver samples from 124 individuals have been analysed for As, Pb, Cu, Zn and Se. Five species have been studied, from the Rallidae (rails), Anatini (dabbling ducks) and Aythyini (pochards) families. Geometric mean bone concentrations 2-3 months after the spill were in the order of Zn > Cu > Pb > Se > As, while liver concentrations were in the order of Zn > Cu > Se > Pb > As. Dry weight bone concentrations ranged from n.d-1.76 mg kg(-1) As, 109.4-247.6 mg kg(-1) Zn, 0.06-1.27 mg kg(-1) Se, n.d-134.11 mg kg(-1) Pb, and 2.18-8.92 mg kg(-1) Cu. Wet weight liver concentrations ranged from n.d-0.34 mg kg(-1) As, 29.8-220.1 mg kg(-1) Zn, 0.15-0.85 mg kg(-1) Se, n.d-3.80 mg kg(-1) Pb, and 7.30-742.96 mg kg(-1) Cu. The most important factor related to the accumulation of these metals was commonly species; however, location and sex also had important effects on liver As levels, location and age affected Cu levels, while Zn and Pb were affected by age, sex and location. Birds from Natural Park areas were found to have significantly higher levels of bone Zn, Pb and Cu, and liver As and Cu than birds from National Park areas. Female birds had higher liver As, Zn and Pb than males; whilst adults appeared to have lower bone As and Zn but higher liver Pb than chicks/juveniles. Although metal concentrations were elevated in certain individuals, in the majority of birds studied, they did not reach levels widely considered to be toxic. However, it would appear that As and Cu liver levels (which may be indicative of short-medium term pollutant exposure) were elevated in waterbirds which died in the spill contaminated Natural Park, 2-3 months after the disaster.

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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.

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Consumption of arsenic (As) wine is a traditional activity during the classic Chinese festival of Duanwu, colloquially known worldwide as the Dragon Boat Day. Arsenic wine is drunk on the morning of the fifth day of the fifth lunar calendar month to commemorate the death of Qu Yuan, a famed Chinese poet who drowned himself in protest of a corrupt government, and to protect against ill fortune. Although realgar minerals are characteristically composed of sparingly soluble tetra-arsenic tetra-sulfides (As(4)S(4)), purity does vary with up to 10% of As being present as non-sulfur bound species, such as arsenate (As(v)) and arsenite (As(III)). Despite, the renewed interest in As speciation and the bioaccessibility of the active As components in realgar based Chinese medicines, little is known about the safety surrounding the cultural practice of drinking As wine. In a series of experiments the speciation and solubility of As in a range of wines were investigated. Furthermore, a simulated gastrointestinal system was employed to predict the impact of digestive processes on As bioavailability. The predominant soluble As species found in all the wines were As(III) and As(v). Based on typical As wine recipes employing 0.1 g realgar mL(-1) wine, the concentration of dissolved As ranged from ca. 100 to 400 mg L(-1) depending on the ethanol content of the preparation: with the As solubility found to be higher in wines with a lower proportion of ethanol. Based on a common 100 mL measure of wine with a concentration of 400 mg As L(-1), the amount of soluble As would equate to around half of the acute minimal lethal dose for adults. This is likely an underestimate of the bioaccessible concentration, as a three-fold increase in bioaccessibility could be observed in the intestinal phase based on the results from the stimulated gastrointestinal system. (C) 2011 Elsevier B.V. All rights reserved.

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Duckweeds are a common macrophyte in paddy and aquatic environments. Here, we investigated arsenic (As) accumulation, speciation and tolerance of the rootless duckweed Wolffia globosa and its potential for As phytofiltration.

When grown with 1 mu M arsenate, W. globosa accumulated two to 10 times more As than four other duckweed or Azolla species tested. W. globosa was able to accumulate > 1000 mg As kg(-1) in frond dry weight (DW), and tolerate up to 400 mg As kg-1 DW. At the low concentration range, uptake rate was similar for arsenate and arsenite, but at the high concentration range, arsenite was taken up at a faster rate.

Arsenite was the predominant As species (c. 90% of the total extractable As) in both arsenate-and arsenite-exposed duckweed. W. globosa was more resistant to external arsenate than arsenite, but showed a similar degree of tolerance internally. W. globosa decreased arsenate in solution rapidly, but also effluxed arsenite.

Wolffia globosa is a strong As accumulator and an interesting model plant to study As uptake and metabolism because of the lack of a root-to-frond translocation

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This study presents the findings of an empirical channel characterisation for an ultra-wideband off-body optic fibre-fed multiple-antenna array within an office and corridor environment. The results show that for received power experiments, the office and corridor were best modelled by lognormal and Rician distributions, respectively [for both line of sight (LOS) and non-LOS (NLOS) scenarios]. In the office, LOS measurements for t and tRMS were both described by the Normal distribution for all channels, whereas NLOS measurements for t and t were Nakagami and Weibull distributed, respectively. For the corridor measurements, LOS for t and t were either Nakagami or normally distributed for all channels, with NLOS measurements for t and t being Nakagami and normally distributed, respectively. This work also shows that achievable diversity gain was influenced by both mutual coupling and cross-correlation co-efficients. Although the best diversity gains were 1.8 dB for three-channel selective diversity combining, the authors present recommendations for improving these results. © The Institution of Engineering and Technology 2013.

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How animals manage time and expend energy has implications for survivorship. Being able to measure key metabolic costs of animals under natural conditions is therefore an important tool in behavioral ecology. One method for estimating activity-specific metabolic rate is via derived measures of acceleration, often 'overall dynamic body acceleration' (ODBA), recorded by an instrumented acceleration logger. ODBA has been shown to correlate well with rate of oxygen consumption (V ?o) in a range of species during activity in the laboratory. This study devised a method for attaching acceleration loggers to decapod crustaceans and then correlated ODBA against concurrent respirometry readings to assess accelerometry as a proxy for activity-specific energy expenditure in a model species, the American lobster Homarus americanus. Where the instrumented animals exhibited a sufficient range of activity levels, positive linear relationships were found between V ?o and ODBA over 20min periods at a range of ambient temperatures (6, 13 and 20°C). Mixed effect linear models based on these data and morphometrics provided reasonably strong predictive power for estimating activity-specific V ?o from ODBA. These V ?o-ODBA calibrations demonstrate the potential of accelerometry as an effective predictor of behavior-specific metabolic rate of crustaceans in the wild during periods of activity. © 2013 Elsevier Inc.

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Obesity has consistently been linked to an increased risk of colorectal cancer, particularly among men. Whether body mass index (BMI) differentially influences the risk across the stages of colorectal cancer development remains unclear. We evaluated the associations of BMI with colorectal adenoma incidence, adenoma recurrence, and cancer in the context of a large screening trial, in which cases and controls had an equal chance for disease detection.

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This chapter considers the radical re-imaginings of traditional Irish step dance in the recent works of Jean Butler and Colin Dunne. In Butler's Does She Take Sugar (2007) and Dunne's Out of Time (2008), the Irish step dancing body is separated from its historical roots in nationalism, from the exhibitionism required by the competitive form, and from the spectacularization of the commercialized theatrical format. In these works, which are both solo pieces performed by the choreographers themselves, the traditional form undergoes a critical interrogation in which the dancers attempt to depart from the determinacy of the traditional technique, while acknowledging its formation of their corporealities; the Irish step dance technique becomes a springboard for creative experimentation. In order to consider the importance of the creative potential revealed by these works, this chapter will contextualize them within the dance background from which they emerged, outlining the history of competitive step dancing in Ireland, the "modernization" of traditional Irish dance with the emergence of Riverdance (1994), and the experiments of Ireland's national folk theatre, Siamsa Tíre.

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This paper investigates the characteristics of the complex received signal in body area networks for two environments at the opposite ends of the multipath spectrum at 2.45 GHz. Important attributes of the complex channel such as the Gaussianity of the quadrature components and power imbalance, which form the basis of many popular fading models, are investigated. It is found that in anechoic environments the assumption of Gaussian distributed quadrature components will not always yield a satisfactory fit. Using a complex received signal model which considers a non-isotropic scattered signal contribution along with the presence of an optional dominant signal component, we use an autocorrelation function originally derived for mobile-to-mobile communications to model the temporal behavior of a range of dynamic body area network channels with considerable success. In reverberant environments, it was observed that the real part of the complex autocorrelation function for body area network channels decayed slightly quicker than that expected in traditional land mobile channels. © 2013 IEEE.

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Arsenic (As) species were quantified by HPLC-HG-AFS in water and vegetables from a rural area of West Bengal (India). Inorganic species predominated in vegetables (including rice) and drinking water; in fact, inorganic arsenic (i-As) represented more than 80% of the total arsenic (t-As) content. To evaluate i-As intake in an arsenic affected rural village, a food survey was carried out on 129 people (69 men and 60 women). The data from the survey showed that the basic diet, of this rural population, was mainly rice and vegetables, representing more than 50% of their total daily food intake. During the periods when nonvegetarian foods (fish and meat) were scarce, the importance of rice increased, and rice alone represented more than 70% of the total daily food intake. The food analysis and the food questionnaires administrated led us to establish a daily intake of i-As of about 170 mu g i-As day(-1), which was above the tolerable daily intake of 150 mu g i-As day(-1), generally admitted. Our results clearly demonstrated that food is a very important source of i-As and that this source should never be forgotten in populations depending heavily on vegetables (mainly rice) for their diet.

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Some retrieved CoCrMo hip implants have shown that abrasive wear is one of the possible wear mechanisms invoked within such joints. To date, little work has focused on the third body abrasion of CoCrMo and therefore there is a general lack of understanding of the effect of abrasive size and volume concentration on the tribo-corrosion performance of the CoCrMo alloys. The present work assessed the tribo-corrosion behaviour of cast CoCrMo (F-75) under various abrasion-corrosion conditions by using a modified microabrasion tester incorporating a three-electrode electrochemical cell. The effects of reduced abrasive size/hardness and volume concentration, as well as the role of proteins on the tribo-corrosion performance of the cast CoCrMo alloy were addressed. The correlation between electrochemical and mechanical processes for different abrasion-corrosion test conditions has been discussed in detail. Results show that the reduction in abrasive size and volume concentration can significantly affect the abrasion-corrosion wear mechanisms and the wear-induced corrosion response of the material. The finding of this study implies that the smaller/softer third body particles generated in vivo could also result in significant wear-induced corrosion and therefore potential metal ion release, which could be potentially detrimental to both the patient health and the life span of the implants. © 2009 Elsevier Ltd. All rights reserved.

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Background: The association between body size and head and neck cancers (HNCA) is unclear, partly because of the biases in case–control studies. Methods: In the prospective NIH–AARP cohort study, 218,854 participants (132,288 men and 86,566 women), aged 50 to 71 years, were cancer free at baseline (1995 and 1996), and had valid anthropometric data. Cox proportional hazards regression was used to examine the associations between body size and HNCA, adjusted for current and past smoking habits, alcohol intake, education, race, and fruit and vegetable consumption, and reported as HR and 95% confidence intervals (CI). Results: Until December 31, 2006, 779 incident HNCAs occurred: 342 in the oral cavity, 120 in the oro- and hypopharynx, 265 in the larynx, 12 in the nasopharynx, and 40 at overlapping sites. There was an inverse association between HNCA and body mass index, which was almost exclusively among current smokers (HR = 0.76 per each 5 U increase; 95% CI, 0.63–0.93), and diminished as initial years of follow-up were excluded. We observed a direct association with waist-to-hip ratio (HR = 1.16 per 0.1 U increase; 95% CI, 1.03–1.31), particularly for cancers of the oral cavity (HR, 1.40; 95% CI, 1.17–1.67). Height was also directly associated with total HNCAs (P = 0.02), and oro- and hypopharyngeal cancers (P < 0.01). Conclusions: The risk of HNCAs was associated inversely with leanness among current smokers, and directly with abdominal obesity and height. Impact: Our study provides evidence that the association between leanness and risk of HNCAs may be due to effect modification by smoking. Cancer Epidemiol Biomarkers Prev; 23(11); 2422–9. ©2014 AACR.

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Hydrogeochemical relationships and the level of arsenic (As) contamination of groundwater in the Haor Basin, a low-lying, semi-natural, region of remnant wetland environs to the northeast of Bangladesh, were studied to assess the As biogeochemical cycling. Most of the shallow and deep tubewells in the study area are contaminated with As (2-331 mu g/l). The relatively higher proportions of Na+ (8-156 mg/l) in groundwater suggest a mixing of connate marine water with freshwater aquifer. Non-significant association between As and PO43- has been found. Highly significant (P <0.001) relationship of As with DOC in groundwater indicates biodegradation of organic matter, creating an overall reducing environment in the aquifer sediments, which facilitates the release of As in the groundwater. The inverse As-Fe, As-Mn, As-Ca and As-Mg relationships in groundwater could be related to the precipitation of Fe-, Mn-, Ca-and Mg-minerals.