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Metal Levels (metal + level)
Selected AbstractsUrinary metal and polycyclic aromatic hydrocarbon biomarkers in boilermakers exposed to metal fume and residual oil fly ashAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 6 2005Sutapa Mukherjee MBBS Abstract Background Boilermakers are occupationally exposed to known carcinogens. Methods The association of urinary 1-hydroxy-pyrene (1-OHP), a biomarker of polycyclic aromatic hydrocarbon (PAH) exposure, with biomarkers of metal exposure (vanadium, chromium, manganese, nickel, copper, and lead) in boilermakers exposed to metal fume from welding and dust particulates from residual oil fly ash (ROFA) was examined. A repeated measures cohort study was conducted during the overhaul of an oil-fired boiler. Twice-daily urine samples were obtained for 5 days and analyzed for cotinine, 1-OHP, and metals. Generalized estimating equations (GEE) were used to model the multivariate relationship of 1-OHP to the explanatory variables. Results Metal and 1-OHP levels were determined for 165 urine samples from 20 boilermakers and these levels increased during the workweek. However, the 1-OHP level was not significantly associated with any individual metal level at any time point. Conclusion This suggests that boilermakers were occupationally exposed to PAH and metals, but 1-OHP as a PAH biomarker was unable to serve as a surrogate marker of metal exposure for the metals measured in this study. Am. J. Ind. Med. 47:484,493, 2005. © 2005 Wiley-Liss, Inc. [source] Reliability Model for Polyimide,Metal Interconnect Shorts in GaAs ASICsQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 8 2004N. Strifas Abstract A physical reliability model has been developed to calculate the time to failure of polyimide,metal multilevel interconnected GaAs components due to the shorts between interconnect metallizations through a polyimide interlayer. The failure mechanism for the shorts between neighboring metals through the polyimide is described as a stress-assisted diffusion process along a polyimide microcrack due to the combination of process defect and high thermal stress concentration. The finite element method has been used to determine the temperature increase during operation and the resulting thermal stress due to the difference in coefficients of thermal expansion (CTEs) of the materials used in the multilevel metallization GaAs module of devices. Numerical methods have been used to solve the partial differential diffusion equations with stress gradients in order to obtain the time to failure of the devices. The time to failure for the shorts between metal level 4 and metal 2 at 123 °C operating temperature was calculated to be 20 h for the conditions analyzed. The activation energy for the failure of the shorts between two level metals was calculated to be 0.48 eV. Copyright © 2004 John Wiley & Sons, Ltd. [source] Assessing trace-metal exposure to American dippers in mountain streams of southwestern British Columbia, CanadaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2005Christy A. Morrissey Abstract To develop a suitable biomonitor of metal pollution in watersheds, we examined trends in exposure to nine trace elements in the diet (benthic invertebrates and fish), feathers (n = 104), and feces (n = 14) of an aquatic passerine, the American dipper (Cinclus mexicanus), from the Chilliwack watershed in British Columbia, Canada. We hypothesized that key differences may exist in exposure to metals for resident dippers that occupy the main river year-round and altitudinal migrants that breed on higher elevation tributaries because of differences in prey metal levels between locations or possible differences in diet composition. Metals most commonly detected in dipper feather samples in decreasing order were Zn > Cu > Hg > Se > Pb > Mn > Cd > Al > As. Resident dipper feathers contained significantly higher mean concentrations of mercury (0.64 ,g/g dry wt), cadmium (0.19 ,g/g dry wt), and copper (10.8 ,g/g dry wt) relative to migrants. Mass balance models used to predict daily metal exposure for dippers with different diets and breeding locations within a watershed showed that variation in metal levels primarily was attributed to differences in the proportion offish and invertebrates in the diet of residents and migrants. In comparing predicted metal exposure values to tolerable daily intakes (TDI), we found that most metals were below or within the range of TDI, except selenium, aluminum, and zinc. Other metals, such as cadmium, copper, and arsenic, were only of concern for dippers mainly feeding on insects; mercury was only of concern for dippers consuming high fish diets. The models were useful tools to demonstrate how shifts in diet and breeding location within a single watershed can result in changes in exposure that may be of toxicological significance. [source] Relationship between soil copper content and copper content of selected crop plants in central ChileENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2001Ricardo Badilla-Ohlbaum Abstract A survey of copper levels in agricultural soils of central Chile revealed two soil clusters,one with a mean copper level of 162 mg/kg and one with a mean copper level of 751 mg/kg of soil. Samples of soils from both soil clusters were characterized on the basis of physicochemical characteristics, and copper extractability was compared by saturation and CaCl2 extraction as well as an acid-leaching procedure (TCLP). We also measured the copper content of various tissues of tomato (Lycopersicon esculentum) and onion (Allium cepa) crops growing on these soils. Other than copper levels, soils from the two clusters were quite similar, with slightly greater levels of molybdenum and cadmium in the high-copper soils. Within each cluster, extracted copper levels and total soil copper levels were not correlated. However, the three extraction procedures solubilized significantly more copper from the high-Cu soils. Mineralogical characterization of the soil particles and depth profiles of soil metal levels in a subsample of sites suggested that highly insoluble copper ore and mining wastes might account for the high copper levels. Neither total nor extractable copper levels allowed statistical prediction of the levels of copper in plant tissue. The edible tissues of both crops had the same mean copper content, regardless of the copper soil level. However, copper contents of stems and leaves were significantly higher for plants growing on the high-Cu soils. These results show that in these soils, high copper levels are associated with very insoluble copper species and thus low bioavailability of copper to crop plants. [source] Current in vivo wear of metal-on-metal bearings assessed by exercise-related rise in plasma cobalt levelJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 11 2006Munir Khan Abstract Baseline metal ion levels are elevated in patients with metal-on-metal (MOM) hip arthroplasty. Interpretation of baseline levels is difficult as measurements are influenced by wear, corrosion, and metal ion release from stored metal in the body. Schmalzried et al. demonstrated that "wear is the function of use, not time." The specific research question we asked was: Does physiological exercise increase the wear of metal-on-metal articulation which can be measured from the plasma metal ion levels? Patients with three different well functioning MOM bearings [two types of resurfacing (BHR 46.8 mm and Cormet 48 mm) and Metasul 28 mm] were included. Blood samples were taken immediately before, immediately after, and 1 h after exercise to determine cobalt and chromium levels. A significant increase (p,<,0.005) in serum cobalt and chromium of 13% and 11%, respectively, was noticed after the exercise. Rise of cobalt levels in patients with a resurfacing MOM was 8.5 times (BHR group) or 6.5 times (Cormet group) larger than in those with a Metasul MOM (p,=,0.021 and p,=,0.047). Neither rise of metal levels nor baseline levels correlated with any other factor (p,>,0.27). Exercise-related elevations of plasma cobalt level provides information on current in vivo wear production that cannot be inferred from a baseline measurement of cobalt levels. Chromium levels cannot provide reliable information on the in vivo wear of the devices. Diameter was the important feature of the implant in determining exercise-related elevations of plasma cobalt level. Exercise-related elevations of plasma cobalt level is a potential in vivo tool to understand and improve the tribology of metal,metal bearings. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:2029,2035, 2006 [source] Four-year study of cobalt and chromium blood levels in patients managed with two different metal-on-metal total hip replacementsJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2003Christian Lhotka Abstract Background: Metal-on-metal total hip prostheses will produce a certain amount of wear debris. This results in increased whole-blood metal levels, which may cause adverse effects. It is not known to what extent the problem has been overcome by advances in alloy technology. Methods: In 259 patients who with total hip replacement, blood cobalt and chromium concentrations were measured with atomic absorption spectrophotometry over a period of four years after arthroplasty. Of the patients enrolled in the study, 131 had been managed with a METASUL® cobalt-chromium alloy metal-on-metal bearing combination, while 128 had been given a SIKOMET®-SM21® cobalt-chromium alloy metal-on-metal combination. The control group consisted of 31 age- and gender-matched subjects. Results: Compared with the controls, all the patients had higher cobalt and chromium levels. Cobalt concentrations were up to 50 times higher, while chromium concentrations were up to 100 times higher. Conclusions: Both systems showed evidence, in the whole-blood samples, of wear debris production by the implants. Therefore, patients managed with metal-on-metal bearing combinations should be carefully monitored in order to ensure that any local or systemic complications are detected early on. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Vitamin and trace metal levels in recessive dystrophic epidermolysis bullosaJOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 6 2004S Ingen-Housz-Oro ABSTRACT Background, In recessive dystrophic epidermolysis bullosa (RDEB), a good nutritional balance is necessary to obtain healing of the chronic wounds. However, involvement of the oral mucosa and oesophagus stenosis may be responsible for severe nutritional deficiencies. Objective, In order to propose an adapted nutritional management, we studied the vitamin and trace metal status of 14 RDEB patients. Methods, Height and weight were measured. Plasma levels of albumin, iron, ferritin, calcium, parathyroid hormone (PTH), folates, vitamins C, D, B12, A, E, B1, B6, PP and B2, zinc, selenium, carnitine and copper were measured. Results, Most patients had a significant growth retardation. We found iron, vitamin D, C, B6, PP, zinc and selenium deficiencies in 36,70% of the patients, without clinical expression, except in one case. Vitamin B1, 12, B2, A/RBP, E/lipids and carnitine were normal. The three patients with gastrostomy feeding had better growth but still a protein deficiency and sometimes vitamin C, B6, PP, zinc and carnitine deficiencies. Conclusion, Vitamin and trace metal deficiencies are frequent in RDEB, even in patients receiving gastrostomy feeding, and often go unrecognized. Regular nutritional evaluation is necessary. Dietary advice and supplements should be given. Enteral feeding by gastrostomy should be discussed in early childhood. [source] Variations in the contents of heavy metals in arable soils of a major urban wetland inlet drainage system of Lake Victoria, UgandaLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 2 2010Jolocam Mbabazi Abstract Little is known about the effects of urbanization on the chemical quality of soils in suburban wetland inlet drainage systems to the Uganda side of Lake Victoria, on which food crops are extensively grown. It is feared that pollution in the soils might eventually enter food chains through such crops being consumed by urban populations unaware of their occurrence. Soil samples were collected from cultivated areas of a major wetland drainage system (Nakivubo Channel), at Kampala, Ubanda, near Lake Victoria and from a rural control wetland site (Senge). The soil from this site had similar properties as those from the urban test site (i.e., soil texture; porosity; humus content). Analysis of heavy metals with atomic absorption spectrophotometry (AAS) yielded the following soil concentration ranges: manganese (190,780), cadmium (<0.001,1.0), zinc (6.0,10.0) and lead (10,20 mg kg,1) dry weight for the control site, and 450,900, 1.0,2.0, 131,185, 40,60 mg kg,1 dry weight, respectively, for the urban wetland, indicative of relatively heavy metal pollution in the suburban drainage system. Heavy metal levels in cocoyam (Colocasia Esculenta) and sugarcane (Saccharum Officinarum) grown on both wetland soils also were evaluated via AAS with a modified wet-acid-digestion technique. The results highlighted high cadium and lead levels (P , 0.0003) in the crops from urban wetland cultivation. Cadmium and lead concentrations in cocoyam from urban wetland soils exceeded those from the control site by 0.17 and 3.54 mg kg,1, respectively. The corresponding results for sugarcane indicated a similar increase of 0.56 and 2.14 mg kg,1 of juice extract. Cadmium and lead levels in both urban wetland crops were higher than the maximum permissible limits of the Codex Alimentarius Commission, indicating that these concentrations pose potential health risks to urban consumers, and call for early counter-measures to combat urban pollution entering the lake. [source] | |||||||||||||