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Lead Concentration (lead + concentration)
Selected AbstractsEpitaxial Sn1-xPbxS nanorods on iso-compositional thin filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2010K. Bente Abstract Based on SnS (Herzenbergite) , SnPbS2 (Teallite) mixed crystals with orthorhombic layer structures, thin films and lawns of Sn1-xPbxS nanorods were produced using hot wall vacuum deposition method (HWVD). The lawn was formed onto the surface of an underlying thin Sn1-xPbxS film which is build by differently oriented blocks. The density of rods arranged like a lawn depends on the metal ratio and substrate temperature. X-ray and TEM analysis of the epitaxial material showed preferential (001) orientation perpendicular to the surface of the glass substrate. The roughness of the films measured by atomic force microscopy was in the range of Rq = 49.5,86.3 nm depending on lead concentration The rods were about 500 nm high and 300 nm in diameter. As revealed by TEM-EDX experiments the droplet at the tip of rods consists of tin. Therefore it is assumed the rods grew via a self-consuming vapor,liquid,solid (VLS) mechanism. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Monitoring of DNA breakage in embryonic stages of the African catfish Clarias gariepinus (Burchell, 1822) after exposure to lead nitrate using alkaline comet assayENVIRONMENTAL TOXICOLOGY, Issue 6 2008Alaa G. M. Osman Abstract Increasing lead contamination in Egyptian ecosystems and high lead concentrations in food items have raised concern for human health and stimulated studies on monitoring ecotoxicological impact of lead-caused genotoxicity. In this work, the alkaline comet assay was modified for monitoring DNA strand breakage in sensitive early life stages of the African catfish Clarias gariepinus. Following exposure to 100, 300, and 500 ,g/L lead nitrate, DNA strand breakage was quantified in embryos at 30, 48, 96, 144, and 168 h post-fertilization (PFS). For quantitative analysis, four commonly used parameters (tail % DNA, %TDNA; head % DNA, %HDNA; tail length, TL; tail moment, TM) were analyzed in 96 nuclei (in triplicates) at each sampling point. The parameter %TDNA revealed highest resolution and lowest variation. A strong correlation between lead concentration, time of exposure, and DNA strand breakage was observed. Here, genotoxicity detected by comet assay preceded the manifested malformations assessed with conventional histology. Qualitative evaluation was carried out using five categories are as follows: undamaged (%TDNA , 10%), low damaged (10% < %TDNA , 25%), median damaged (25 < %TDNA , 50%), highly damaged (50 < %TDNA , 75%), and extremely damaged (%TDNA > 75%) nuclei confirming a dose and time-dependent shift towards increased frequencies of highly and extremely damaged nuclei. A protective capacity provided by a hardened chorion is a an interesting finding in this study as DNA damage in the prehatching stages 30 h-PFS and 48 h-PFS was low in all treatments (qualitative and quantitative analyses). These results clearly show that the comet assay is a sensitive tool for the detection of genotoxicity in vulnerable early life stages of the African catfish and is a method more sensitive than histological parameters for monitoring genotoxic effects. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source] Lead accumulation in feathers of nestling black-crowned night herons (Nycticorax nycticorax) experimentally treated in the fieldENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2003Nancy H. Golden Abstract Although lead can attain high concentrations in feathers, interpretation of the biological significance of this phenomenon is difficult. As part of an effort to develop and validate noninvasive methods to monitor contaminant exposure in free-ranging birds, lead uptake by feathers of nestling black-crowned night herons (Nycticorax nycticorax) was evaluated in a controlled exposure study. Four- to 6-d-old heron nestlings (one/nest) at Chincoteague Bay, Virginia (USA), received a single intraperitoneal injection of dosing vehicle (control, n = 7) or a dose of lead nitrate in water (0.01, 0.05, or 0.25 mg Pb/g body wt of nestling; n = 6 or 7/dose) chosen to yield feather lead concentrations found at low- to moderately polluted sites. Nestlings were euthanized at 15 d of age. Lead accumulation in feathers was associated with concentrations in bone, kidney, and liver (r = 0.32,0.74, p < 0.02) but exhibited only modest dose dependence. Blood delta-aminolevulinic acid dehydratase activity was inhibited by lead, although effects on other biochemical endpoints were marginal. Tarsus growth rate was inversely related to feather lead concentration. Culmen growth rate was depressed in nestlings treated with the highest dose of lead but not correlated with feather lead concentration. These findings provide evidence that feathers of nestling herons are a sensitive indicator of lead exposure and have potential application for the extrapolation of lead concentrations in other tissues and the estimation of environmental lead exposure in birds. [source] Comparative studies of Oryza sativa L. husk and chitosan as lead adsorbentJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2006Mohamed Mohamed Daud Zulkali Abstract The adsorption capacity of two low-cost adsorbents, Oryza sativa L. husk and chitosan, was studied. Lead solution was used as the adsorbate. The effect of initial lead concentration, pH, temperature, weight of adsorbent, particle size and contact time on lead uptake was investigated. It was found that the isotherm data were well described by the Freundlich isotherm for both adsorbents. The adsorption capacities of rice husk and chitosan were 5.69 and 8.31 mg g,1, respectively. It was shown that chitosan was more effective than rice husk. Copyright © 2005 Society of Chemical Industry [source] Changes in brain biogenic amines and haem biosynthesis and their response to combined administration of succimers and Centella asiatica in lead poisoned ratsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2006Geetu Saxena This study was designed to investigate the therapeutic potential of meso 2,3-dimercaptosuccinic acid (DMSA) and one of its monoesters, monoisoamyl DMSA (MiADMSA), individually or when administered in combination with an extract of Centella asiatica against experimental lead intoxication in rats. Biochemical variables indicative of alterations in the central nervous system and haem biosynthesis were investigated to determine the toxicity in male Wistar rats. Thirty five rats were exposed to 0.2% lead acetate for 10 weeks, followed by 10 days of treatment with DMSA and MiADMSA (50 mg kg,1, i.p., once daily) alone and in combination with C. asiatica (200 mg kg,1, p.o., once daily). Biochemical variables indicative of oxidative stress and brain biogenic amines, along with lead concentration in blood and brain, were measured. Lead exposure caused a significant depletion of blood and brain ,-aminolevulinic acid dehydratase (ALAD) activity, an important enzyme of the haem biosynthesis pathway, and glutathione (GSH) level. These changes were accompanied by a marked increase in reactive oxygen species (ROS) level, thiobarbituric acid reactive substances (TBARS), ,-aminolevulinic acid synthase (ALAS) and oxidized glutathione (GSSG) activity in blood and brain. Significant depletion of brain noradrenaline (norepinephrine, NE), 5-hydroxytryptamine (5-HT), dopamine (DA) and acetylcholinesterase (AChE) also were observed following lead exposure. Also seen was a significant depletion in brain glutathione peroxidase (GPx), glutathione S-transferase (GST) and monoamine oxidase activity, as well as blood and brain superoxide dismutase (SOD) activity. These biochemical changes were correlated with an increased uptake of lead in blood and brain. Combined administration of MiADMSA and C. asiatica was most effective in reducing these alterations, including biogenic amines, besides reducing body lead burden, compared with individual treatment with MiADMSA. Certain other biochemical variables responded favourably to combination therapy and monotherapy with MiADMSA. Thus, supplementation of C. asiatica during chelation could be recommended for achieving optimum effects of chelation therapy. [source] Effect of Lead Content on the Structure and Electrical Properties of Pb((Zn1/3Nb2/3)0.5(Zr0.47Ti0.53)0.5)O3 CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2001Huiqing Fan The effects of lead content on the structure and electrical properties of Pb((Zn1/3Nb2/3)0.5(Zr0.47Ti0.53)0.5)O3 ceramics were investigated. Specimens with various lead concentrations were prepared by the conventional oxide-mixing method. When the lead concentration was slightly less than the stoichiometric amount, a large amount of pyrochlore phase was formed along with the perovskite phase. On the other hand, excessive amounts of lead led to the formation of PbO on the surface of the specimen. These second phases were seriously detrimental to electromechanical properties. The highest piezoelectric properties were observed when an excess of 1 mol% lead was added. By optimizing the specimen composition, excellent piezoelectric and dielectric properties (kp= 0.7, d33= 490 pC/N, and ,m= 15000) were obtained. [source] Cadmium and lead in Hungarian porcine products and tissuesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2005Zoltan Gyõri Abstract Samples of kidney, blood, lungs, hair, heart, liver, spleen, muscle, ear, rib, skin and faeces were obtained from 200 fattened pigs in 10 abattoirs across Hungary. These were analysed in triplicate for cadmium and lead concentrations by atomic absorption spectrophotometry. The highest concentrations of cadmium were found in the kidney, followed by hair and faeces and then liver, heart and lungs. Lead concentrations were greater in the hair and faeces than other tissues. Both lead and cadmium concentrations in meat and offal were below the legal limits. There was more variation in lead than cadmium concentrations between abattoirs, and across abattoirs there was no correlation between concentrations of the two elements. Blood lead concentration was correlated with the lead concentration in bone, kidney, liver, spleen and lungs, and was a better indicator of lead contamination than hair lead concentration. The cadmium concentrations of the kidney, liver, spleen, lungs and faeces were highly correlated, and it is suggested that faeces is the best on-farm indicator of cadmium contamination. Across animals, blood cadmium correlated less closely with the cadmium concentration of the body tissues than it did with the lead concentration, demonstrating positive interaction between the two elements. By contrast, hair and to a lesser extent bone cadmium concentrations were negatively correlated with the lead concentration of most tissues. It is concluded that lead and cadmium concentrations in pigs are best monitored in blood and faeces concentrations, respectively. Copyright © 2005 Society of Chemical Industry [source] The effect of adding cadmium and lead alone or in combination to the diet of pigs on their growth, carcase composition and reproductionJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2003Clive Phillips Abstract Limits for cadmium and lead concentrations in food animal products have been established independently, whereas these two toxic metals often co-exist in polluted regions. Weaned pigs (60) were allocated to ten treatments: control; low (0.5 mg kg,1), medium (1 mg kg,1) or high cadmium (2.5 mg kg,1) in feed; low (5 mg kg,1) medium (10 mg kg,1) or high (25 mg kg,1) lead in feed; and low, medium and high cadmium plus lead in feed. Growth rates and concentrations of cadmium and lead in body tissues (kidney, liver, spleen, lungs, heart, testicle, ribs, hair and teeth) were measured after 137 days. There was a similar reduction in weight gain for pigs in the cadmium and lead treatments, compared with the control, and a greater reduction for the pigs in the cadmium plus lead treatments. The reduction increased with the level of metal included. There was an increase in cadmium concentration of all tissues and blood with increasing feed cadmium concentration, which was usually less when lead was also included in the feed. There was also an increase in tissue lead concentration with increasing dietary lead, and this was in most cases increased when cadmium was also included in the feed. The most sensitive tissues for cadmium and lead exposure were the kidney, liver, hair and teeth, and regression equations were developed for the accumulation rates in these tissues. Tissue and blood cadmium concentrations increased gradually with increasing dietary lead, whereas tissue lead concentration was not sensitive to dietary cadmium, except in the ribs and heart. In a second experiment, 10 sows were allocated to a control diet or the same diet but with a supplement of cadmium and lead. The birth weight of piglets was decreased by the supplement and their mortality increased. Lead accumulated most in the ovary and oviduct of the sows, and there were increases in the lead and, to a lesser extent, cadmium concentrations of tissues of the piglets from these sows. Copyright © 2003 Society of Chemical Industry [source] Lead,Natural rubber composites as gamma radiation shields.POLYMER COMPOSITES, Issue 4 2002II: High concentration Natural rubber composites were prepared by the incorporation of different lead concentration, namely: 100, 300, 500, 1000, 1500 and 2000 phr to be used as gamma radiation shields. A non-linear dependence of the attenuation coefficient upon the lead concentration was observed for both 60Co and 137Cs as gamma radiation sources. Sample containing the ultimate lead concentration (2000 phr) and thickness 1 mm was found to have 0.336 mm and 0.383 mm lead equivalent for 60Co and 137Cs respectively. Electrical and mechanical properties of the investigated composites were also measured. [source] Association between bone lead concentration and blood pressure among young adultsAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2002Fredric Gerr MD Abstract Background Occupational and environmental exposure to lead has been examined for its effect on blood pressure (BP) in adults with varying results. The present analyses assessed the association between bone lead concentration and BP in early adult life in persons exposed during childhood. Methods Study participants included young adult members of two cohorts with different past histories of lead exposure. Lead exposure was assessed using noninvasive K-X-ray fluorescence spectroscopy to quantify bone lead concentration, an index of long-term lead exposure superior to current blood lead concentration. Systolic and diastolic BP measurements were obtained using conventional clinical methods. Multiple linear regression models were constructed to allow for control of covariates of BP identified a priori. Results Analyses were performed on 508 participants. While controlling for potential confounders, systolic BP was 4.3 mm,Hg greater among members of the highest of four bone lead concentration groups (>,10 ,gPb/g bone) when compared with the lowest bone lead concentration group (<,1 ,gPb/g bone; P,=,0.004), and diastolic BP was 2.8 mm,Hg greater among members of the highest bone lead concentration group when compared with the lowest bone lead concentration group (P,=,0.03). Conclusions These results suggest that substantial lead exposure during childhood can increase BP during young adulthood. Am. J. Ind. Med. 42:98,106, 2002. © 2002 Wiley-Liss, Inc. [source] Evaluation of a soil-amendment process demonstration for reducing the bioavailability of leadREMEDIATION, Issue 4 2002Edwin F. Barth The U.S. Environmental Protection Agency (EPA) evaluated an in-situ application of a soil-amendment process at a residential site that was contaminated with lead. The goal of the evaluation was to determine if the soil-amendment process resulted in lower concentrations of bioavailable lead in the contaminated soils. The relative bioavailability of lead (bioaccessible lead) was measured by an in vitro test procedure that uses a highly acidic extraction procedure to simulate human digestive processes. The soil-amendment demonstration showed that the 11.2 percent mean reduction in bioavailable lead concentration between untreated and treated soils was not statistically different. © 2002 Wiley Periodicals, Inc. [source] Monitoring of DNA breakage in embryonic stages of the African catfish Clarias gariepinus (Burchell, 1822) after exposure to lead nitrate using alkaline comet assayENVIRONMENTAL TOXICOLOGY, Issue 6 2008Alaa G. M. Osman Abstract Increasing lead contamination in Egyptian ecosystems and high lead concentrations in food items have raised concern for human health and stimulated studies on monitoring ecotoxicological impact of lead-caused genotoxicity. In this work, the alkaline comet assay was modified for monitoring DNA strand breakage in sensitive early life stages of the African catfish Clarias gariepinus. Following exposure to 100, 300, and 500 ,g/L lead nitrate, DNA strand breakage was quantified in embryos at 30, 48, 96, 144, and 168 h post-fertilization (PFS). For quantitative analysis, four commonly used parameters (tail % DNA, %TDNA; head % DNA, %HDNA; tail length, TL; tail moment, TM) were analyzed in 96 nuclei (in triplicates) at each sampling point. The parameter %TDNA revealed highest resolution and lowest variation. A strong correlation between lead concentration, time of exposure, and DNA strand breakage was observed. Here, genotoxicity detected by comet assay preceded the manifested malformations assessed with conventional histology. Qualitative evaluation was carried out using five categories are as follows: undamaged (%TDNA , 10%), low damaged (10% < %TDNA , 25%), median damaged (25 < %TDNA , 50%), highly damaged (50 < %TDNA , 75%), and extremely damaged (%TDNA > 75%) nuclei confirming a dose and time-dependent shift towards increased frequencies of highly and extremely damaged nuclei. A protective capacity provided by a hardened chorion is a an interesting finding in this study as DNA damage in the prehatching stages 30 h-PFS and 48 h-PFS was low in all treatments (qualitative and quantitative analyses). These results clearly show that the comet assay is a sensitive tool for the detection of genotoxicity in vulnerable early life stages of the African catfish and is a method more sensitive than histological parameters for monitoring genotoxic effects. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source] Lead accumulation in feathers of nestling black-crowned night herons (Nycticorax nycticorax) experimentally treated in the fieldENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2003Nancy H. Golden Abstract Although lead can attain high concentrations in feathers, interpretation of the biological significance of this phenomenon is difficult. As part of an effort to develop and validate noninvasive methods to monitor contaminant exposure in free-ranging birds, lead uptake by feathers of nestling black-crowned night herons (Nycticorax nycticorax) was evaluated in a controlled exposure study. Four- to 6-d-old heron nestlings (one/nest) at Chincoteague Bay, Virginia (USA), received a single intraperitoneal injection of dosing vehicle (control, n = 7) or a dose of lead nitrate in water (0.01, 0.05, or 0.25 mg Pb/g body wt of nestling; n = 6 or 7/dose) chosen to yield feather lead concentrations found at low- to moderately polluted sites. Nestlings were euthanized at 15 d of age. Lead accumulation in feathers was associated with concentrations in bone, kidney, and liver (r = 0.32,0.74, p < 0.02) but exhibited only modest dose dependence. Blood delta-aminolevulinic acid dehydratase activity was inhibited by lead, although effects on other biochemical endpoints were marginal. Tarsus growth rate was inversely related to feather lead concentration. Culmen growth rate was depressed in nestlings treated with the highest dose of lead but not correlated with feather lead concentration. These findings provide evidence that feathers of nestling herons are a sensitive indicator of lead exposure and have potential application for the extrapolation of lead concentrations in other tissues and the estimation of environmental lead exposure in birds. [source] Spatial point-process statistics: concepts and application to the analysis of lead contamination in urban soil,ENVIRONMETRICS, Issue 4 2005Christian Walter Abstract This article explores the use of spatial point-process analysis as an aid to describe topsoil lead distribution in urban environments. The data used were collected in Glebe, an inner suburb of Sydney. The approach focuses on the locations of punctual events defining a point pattern, which can be statistically described through local intensity estimates and between-point distance functions. F -, G - and K -surfaces of a marked spatial point pattern were described and used to estimate nearest distance functions over a sliding band of quantiles belonging to the marking variable. This provided a continuous view of the point pattern properties as a function of the marking variable. Several random fields were simulated by selecting points from random, clustered or regular point processes and diffusing them. Recognition of the underlying point process using variograms derived from dense sampling was difficult because, structurally, the variograms were very similar. Point-event distance functions were useful complimentary tools that, in most cases, enabled clear recognition of the clustered processes. Spatial sampling quantile point pattern analysis was defined and applied to the Glebe data set. The analysis showed that the highest lead concentrations were strongly clustered. The comparison of this data set with the simulation confidence limits of a Poisson process, a short-radius clustered point process and a geostatistical simulation showed a random process for the third quartile of lead concentrations but strong clustering for the data in the upper quartile. Thus the distribution of topsoil lead concentrations over Glebe may have resulted from several contamination processes, mainly from regular or random processes with large diffusion ranges and short-range clustered processes for the hot spots. Point patterns with the same characteristics as the Glebe experimental pattern could be generated by separate additive geostatistical simulation. Spatial sampling quantile point patterns statistics can, in an easy and accurate way, be used complementarily with geostatistical methods. Copyright © 2005 John Wiley & Sons, Ltd. [source] Effect of Lead Content on the Structure and Electrical Properties of Pb((Zn1/3Nb2/3)0.5(Zr0.47Ti0.53)0.5)O3 CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2001Huiqing Fan The effects of lead content on the structure and electrical properties of Pb((Zn1/3Nb2/3)0.5(Zr0.47Ti0.53)0.5)O3 ceramics were investigated. Specimens with various lead concentrations were prepared by the conventional oxide-mixing method. When the lead concentration was slightly less than the stoichiometric amount, a large amount of pyrochlore phase was formed along with the perovskite phase. On the other hand, excessive amounts of lead led to the formation of PbO on the surface of the specimen. These second phases were seriously detrimental to electromechanical properties. The highest piezoelectric properties were observed when an excess of 1 mol% lead was added. By optimizing the specimen composition, excellent piezoelectric and dielectric properties (kp= 0.7, d33= 490 pC/N, and ,m= 15000) were obtained. [source] Cadmium and lead in Hungarian porcine products and tissuesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2005Zoltan Gyõri Abstract Samples of kidney, blood, lungs, hair, heart, liver, spleen, muscle, ear, rib, skin and faeces were obtained from 200 fattened pigs in 10 abattoirs across Hungary. These were analysed in triplicate for cadmium and lead concentrations by atomic absorption spectrophotometry. The highest concentrations of cadmium were found in the kidney, followed by hair and faeces and then liver, heart and lungs. Lead concentrations were greater in the hair and faeces than other tissues. Both lead and cadmium concentrations in meat and offal were below the legal limits. There was more variation in lead than cadmium concentrations between abattoirs, and across abattoirs there was no correlation between concentrations of the two elements. Blood lead concentration was correlated with the lead concentration in bone, kidney, liver, spleen and lungs, and was a better indicator of lead contamination than hair lead concentration. The cadmium concentrations of the kidney, liver, spleen, lungs and faeces were highly correlated, and it is suggested that faeces is the best on-farm indicator of cadmium contamination. Across animals, blood cadmium correlated less closely with the cadmium concentration of the body tissues than it did with the lead concentration, demonstrating positive interaction between the two elements. By contrast, hair and to a lesser extent bone cadmium concentrations were negatively correlated with the lead concentration of most tissues. It is concluded that lead and cadmium concentrations in pigs are best monitored in blood and faeces concentrations, respectively. Copyright © 2005 Society of Chemical Industry [source] The effect of adding cadmium and lead alone or in combination to the diet of pigs on their growth, carcase composition and reproductionJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2003Clive Phillips Abstract Limits for cadmium and lead concentrations in food animal products have been established independently, whereas these two toxic metals often co-exist in polluted regions. Weaned pigs (60) were allocated to ten treatments: control; low (0.5 mg kg,1), medium (1 mg kg,1) or high cadmium (2.5 mg kg,1) in feed; low (5 mg kg,1) medium (10 mg kg,1) or high (25 mg kg,1) lead in feed; and low, medium and high cadmium plus lead in feed. Growth rates and concentrations of cadmium and lead in body tissues (kidney, liver, spleen, lungs, heart, testicle, ribs, hair and teeth) were measured after 137 days. There was a similar reduction in weight gain for pigs in the cadmium and lead treatments, compared with the control, and a greater reduction for the pigs in the cadmium plus lead treatments. The reduction increased with the level of metal included. There was an increase in cadmium concentration of all tissues and blood with increasing feed cadmium concentration, which was usually less when lead was also included in the feed. There was also an increase in tissue lead concentration with increasing dietary lead, and this was in most cases increased when cadmium was also included in the feed. The most sensitive tissues for cadmium and lead exposure were the kidney, liver, hair and teeth, and regression equations were developed for the accumulation rates in these tissues. Tissue and blood cadmium concentrations increased gradually with increasing dietary lead, whereas tissue lead concentration was not sensitive to dietary cadmium, except in the ribs and heart. In a second experiment, 10 sows were allocated to a control diet or the same diet but with a supplement of cadmium and lead. The birth weight of piglets was decreased by the supplement and their mortality increased. Lead accumulated most in the ovary and oviduct of the sows, and there were increases in the lead and, to a lesser extent, cadmium concentrations of tissues of the piglets from these sows. Copyright © 2003 Society of Chemical Industry [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] Plasma-lead concentration: Investigations into its usefulness for biological monitoring of occupational lead exposureAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2006Ingvar A. Bergdahl Abstract Background The lead concentration in plasma is correlated to that in whole blood with a two to fourfold variation. It has never been investigated if this variation is inter-individual. Methods Lead and hemoglobin were determined in blood and plasma from 13 lead workers with a history of relatively high blood-lead concentrations, sampled three times during 1 day. The variation in the distribution of lead between cells and plasma was studied, but not the variation in the lead concentrations as such. Results Blood hemoglobin decreased with rising plasma lead (0.9,3.0 µg/L). Regarding the distribution of lead, no effect of current exposure during the day or of recent meals appeared. As much as 84% of the overall variance of the distribution of lead between cells and plasma could be attributed to individual factors. After adjustment for erythrocyte volume fraction this decreased to 67%. Plasma samples with elevated hemoglobin concentrations (due to in vitro hemolysis) had somewhat elevated lead concentrations. Conclusions Plasma lead is not significantly altered by variation in a single day's exposure and, therefore, the choice of time of the day is not critical for sampling. However, plasma lead is negatively correlated to blood hemoglobin and mild hemolysis (not visible by the eye) in a sample may increase plasma lead with up to 30%. Finally, plasma provides lead exposure information that differs from whole blood, but it is not clear which one of these is the biomarker with the closest relation to exposure and/or effects. Am. J. Ind. Med. 49:93,101, 2006. © 2006 Wiley-Liss, Inc. [source] A pilot evaluation of tibia lead concentrations in TaiwanAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 2 2001Andrew C. Todd Abstract Background The aims of this study were to examine some of the factors that influence tibia lead concentrations, tibia lead x-ray fluorescence measurement uncertainty and blood lead concentrations, and to compare tibia lead concentrations in Taiwanese lead workers to those observed in lead workers from other countries. Methods A pilot evaluation of 43 adult lead workers who underwent measurements of tibia lead and blood lead concentrations. Results Mean and maximum tibia lead concentrations were 54 ,g of Pb per g of bone mineral(,g/g) and 193 ,g/g, respectively. Mean and maximum blood lead concentrations were 44 ,g/dl and 92 ,g/dl, respectively. Conclusion Past occupational control of lead exposure in Taiwan, ROC, did not prevent these workers from accumulating tibia lead concentrations greater than those in similar workers elsewhere in the world. Am. J. Ind. Med. 40:127,132, 2001. © 2001 Wiley-Liss, Inc. [source] | |||||||||||||||||||