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Mercury Concentrations (mercury + concentration)

Distribution by Scientific Domains

Medical Sciences	23%
Earth and Environmental Science	15%
Chemistry	11%

Selected Abstracts

Protective effect of Copalite surface coating on mercury release from dental amalgam following treatment with carbamide peroxide

DENTAL TRAUMATOLOGY, Issue 3 2000
I. Rotstein
Abstract , The effect of Copalite coating on mercury release from dental amalgam following treatment with 10%, 20%, 30% and 40% carbamide peroxide was assessed in vitro, using a cold-vapour atomic absorption Mercury Analyzer System. Eighty samples of dental amalgam were automatically mixed in a dental amalgamator and condensed into silicon embedding molds. Forty amalgam samples were coated with three uniform layers of Copalite intermediary varnish and the other 40 samples were left uncoated. The coated and non-coated amalgam samples were exposed for 24 h to 10%, 20%, 30% or 40% carbamide peroxide preparations and compared with samples exposed to phosphate buffer. In the non-coated samples a significant increase of mercury concentration in solution was found following exposure to all carbamide peroxide preparations tested. Mercury concentration was directly related to carbamide peroxide concentration. In the Copalite-coated samples, significantly lower concentrations of mercury in solution were found as compared to the non-coated samples (P<0.01). In conclusion, exposure of amalgam restorations to 10%,40% carbamide peroxide-based bleaching agents increased the mercury release. Pre-coating of the external amalgam surfaces with Copalite significantly reduced the release of mercury. [source]

Concentrations of selenium and mercury in eared grebes (Podiceps nigricollis) from Utah's great Salt Lake, USA

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2009
Michael R. Conover
Abstract We examined selenium and mercury concentrations in eared grebes (Podiceps nigricollis) that spent the fall of 2006 on the Great Salt Lake (UT, USA), where their diet consisted mainly of brine shrimp (Artemia franciscana). Selenium concentrations in livers varied based on when the grebes were collected (lower in September [mean ± standard error, 9.4 ± 0.7 ,g/g dry wt] than in November [14.5 ± 1.4 ,g/g]), on where the birds were collected on the Great Salt Lake (Antelope Island, 8.6 ± 0.5 ,g/g; Stansbury Island, 15.2 ± 1.4 ,g/g), and on the grebe's age (juveniles, 8.5 ± 1.5 ,g/g; adults, 15.8 ± 1.3 ,g/g), but not by sex. Selenium concentrations in blood differed only by collection site (Antelope Island, 16.8 ± 2.3 ,g/g; Stansbury Island, 25.4 ± 3.0 ,g/g). Mercury concentration in the blood of grebes varied by when the grebes were collected (September, 5.6 ± 0.5 ,g/g; November, 8.4 ± 1.2 ,g/g), where the birds were collected (Antelope Island, 4.3 ± 0.5 ,g/g; Stansbury Island, 10.1 ± 2.6 ,g/g), and the grebe's age (juveniles, 5.5 ± 0.8 ,g/g; adults, 8.4 ± 1.0 ,g/g), but not by sex. Selenium concentrations in blood were correlated with selenium concentrations in the liver and with mercury concentrations in both blood and liver. Body mass of grebes increased dramatically from September (381 ± 14 g wet wt) to November (591 ± 11 g). Body, liver, and spleen mass either were not correlated with selenium or mercury concentrations or the relationship was positive. These results suggest that high mercury and selenium levels were not preventing grebes from increasing or maintaining mass. [source]

Detoxification and antioxidant effects of curcumin in rats experimentally exposed to mercury

JOURNAL OF APPLIED TOXICOLOGY, Issue 5 2010
Rakhi Agarwal
Abstract Curcumin, a safe nutritional component and a highly promising natural antioxidant with a wide spectrum of biological functions, has been examined in several metal toxicity studies, but its role in protection against mercury toxicity has not been investigated. Therefore, the detoxification and antioxidant effects of curcumin were examined to determine its prophylactic/therapeutic role in rats experimentally exposed to mercury (in the from of mercuric chloride-HgCl2, 12,µmol,kg,1 b.w. single intraperitoneal injection). Curcumin treatment (80,mg,kg,1 b.w. daily for 3 days, orally) was found to have a protective effect on mercury-induced oxidative stress parameters, namely, lipid peroxidation and glutathione levels and superoxide dismutase, glutathione peroxidase and catalase activities in the liver, kidney and brain. Curcumin treatment was also effective for reversing mercury-induced serum biochemical changes, which are the markers of liver and kidney injury. Mercury concentration in the tissues was also decreased by the pre/post-treatment with curcumin. However, histopathological alterations in the liver and kidney were not reversed by curcumin treatment. Mercury exposure resulted in the induction of metallothionein (MT) mRNA expressions in the liver and kidney. Metallothionein mRNA expression levels were found to decrease after the pre-treatment with curcumin, whereas post-treatment with curcumin further increased MT mRNA expression levels. Our findings suggest that curcumin pretreatment has a protective effect and that curcumin can be used as a therapeutic agent in mercury intoxication. The study indicates that curcumin, an effective antioxidant, may have a protective effect through its routine dietary intake against mercury exposure. [source]

Organochlorine pesticides and mercury in cottonmouths (Agkistrodon piscivorus) from northeastern Texas, USA,

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2005
Thomas R. Rainwater
Abstract Dspite their ecological importance andglobal decline, snakes remain poorly studied in ecotoxicology. In this study, we examined organochlorine (OC) pesticide and mercury accumulation in cottonmouths (Agkistrodon piscivorus) living on a contaminated site in northeastern Texas (USA). Mercury and p,p,-dichlorodiphenyldichloroethylene (p,p,-DDE) were detected in all snakes examined. Other OCs, including p,p,-dichlorodiphenyltrichloroethane (p,p,-DDT), methoxychlor, aldrin, and heptachlor, also were detected, but less frequently. Concentrations of p,p,-DDE were higher in fat than in liver, while mercury concentrations were highest in liver, followed by kidney and tail clips. One animal contained the highest mercury concentration yet reported for a snake (8,610 ng/g). Mercury concentrations in liver and kidney were higher in males than females, while no intersex differences in p,p,-DDE concentrations were observed. Concentrations of p,p,-DDE in fat were correlated positively with body size in male cottonmouths but not females, suggesting a slower rate of accumulation in females. Body size strongly predicted mercury concentrations in liver, kidney, and tail clips of both sexes. Tail clips were strong predictors of mercury in liver and kidney in males but not females, suggesting possible sex-dependent differences in mercury toxicokinetics. Both long-term field studies and controlled laboratory investigations are needed to adequately assess the response of cottonmouths to chronic contaminant exposure. [source]

Exposure, health complaints and cognitive performance among employees of an MRI scanners manufacturing department

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2006
Frank de Vocht MSc
Abstract Purpose To assess sensory effects and other health complaints that are reported by system testers working near magnetic resonance imaging (MRI) magnets, realizing that it is believed that exposure up to 8 T is safe for humans. Materials and Methods Levels of exposure to static magnetic fields (SMFs), movement speed during exposure, health complaints, and cognitive performance among employees in an MRI-manufacturing department and at a reference department have been analyzed. Mercury concentrations in urine samples were determined to analyze whether they depend on exposure to SMFs. Results Average exposure of system testers was 25.9 mT/8 hours at a 1.0-T system and 40.4 mT/8 hours at a 1.5-T system. Vertigo, metallic taste, and concentration problems were more reported among workers of MRI-fabrication than in the reference department. Cognitive performance was tested outside the SMF, and no significant changes were detected. Conclusion This study suggests that any effects on cognitive functions are acute and transient and disappear rapidly after exposure has ended. All complaints, except for headaches, were more frequently reported by "fast movers" than by "slow movers," and depended on field strength and duration of exposure. Mercury-levels in urine were not affected. J. Magn. Reson. Imaging 2006. © 2005 Wiley-Liss, Inc. [source]

Mercury comparisons between farmed and wild Atlantic salmon (Salmo salar L.) and Atlantic cod (Gadus morhua L.)

AQUACULTURE RESEARCH, Issue 10 2009
L B Jardine
Abstract Wild and farmed Atlantic salmon (Salmo salar L.) and Atlantic cod (Gadus morhua L.) were collected to assess changes in mercury with size in wild vs. farmed fish. Mercury concentrations were compared with Health Canada and United States Environmental Protection Agency consumption guidelines. Lipid dilution of mercury was examined by comparing lipid-extracted (LE) and non-lipid-extracted (NLE) flesh samples in both farmed and wild fish. Mercury concentrations in the flesh and liver of farmed salmon were significantly lower than concentrations in wild salmon of similar fork length (P<0.001), possibly due to growth dilution in rapidly growing farmed fish. Mercury concentrations were higher in LE tissue compared with NLE (P<0.05), suggesting lipid dilution of mercury in farmed fish with a high lipid content. Farmed cod, which do not grow more rapidly than wild cod, did not have significantly different flesh and liver concentrations compared with wild cod of similar fork length (P>0.05). Between species of farmed fish, cod had significantly higher mercury concentrations than salmon (P<0.05), but neither farmed nor wild salmon mercury concentrations exceeded federal consumption guidelines. These results suggest that rapid growth rates and a high lipid content may play important roles in regulating concentrations of contaminants such as mercury. [source]

Protective effect of Copalite surface coating on mercury release from dental amalgam following treatment with carbamide peroxide

A nonlethal microsampling technique to monitor the effects of mercury on wild bird eggs

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2009
Katherine R. Stebbins
Abstract Methylmercury is the predominant chemical form of mercury reported in the eggs of wild birds, and the embryo is the most sensitive life stage to methylmercury toxicity. Protective guidelines have been based mainly on captive-breeding studies with chickens (Gallus gallus), mallards (Anas platyrhynchos), and ring-necked pheasants (Phasianus colchicus) or on field studies where whole eggs were collected and analyzed and the effects of the mercury were measured based on the reproductive success of the remaining eggs. However, both of these methods have limitations. As an alternative, we developed a technique that involves extracting a small sample of albumen from a live egg, sealing the egg, returning the egg to its nest to be naturally incubated by the parents, and then relating the hatching success of this microsampled egg to its mercury concentration. After first developing this technique in the laboratory using chicken and mallard eggs, we selected the laughing gull (Larus atricilla) and black-necked stilt (Himantopus mexicanus) as test subjects in the field. We found that 92% of the microsampled laughing gull eggs met our reproductive endpoint of survival to the beginning of hatching compared to 100% for the paired control eggs within the same nests. Microsampled black-necked stilt eggs exhibited 100% hatching success compared to 93% for the paired control eggs. Our results indicate that microsampling is an effective tool for nonlethally sampling mercury concentrations in eggs and, as such, can be used for monitoring sensitive species, as well as for improving studies that examine the effects of mercury on avian reproduction. [source]

High within-individual variation in total mercury concentration in seabird feathers

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2008
Alexander L. Bond
Abstract To our knowledge, no rigorous assessment of the variation in mercury concentrations within individual seabirds has been made using multiple body feathers. We analyzed five feathers from individual Arctic terns (Sterna paradisaea Pontoppidan), common terns (Sterna hirundo L.), and Leach's storm-petrels (Oceanodroma leucorhoa Veillot) and found levels of within-individual variability higher than population or time-series variation. Using a randomization procedure, we found a large range of possible mercury concentrations if only one feather per individual had been sampled. Researchers should report within-individual variability in future studies. [source]

Organochlorine pesticides and mercury in cottonmouths (Agkistrodon piscivorus) from northeastern Texas, USA,

Total imprecision of exposure biomarkers: implications for calculating exposure limits

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 10 2007
Philippe Grandjean MD
Abstract Background Assessment of the imprecision of exposure biomarkers usually focuses on laboratory performance only. Unrecognized imprecision leads to underestimation of the true toxicity of the exposure. We have assessed the total imprecision of exposure biomarkers and the implications for calculation of exposure limits. Methods In a birth cohort study, mercury concentrations in cord blood, cord tissue, and maternal hair were used as biomarkers of prenatal methylmercury exposure. We determined their mutual correlations and their associations with the child's neurobehavioral outcome variables at age 7 years. With at least three exposure parameters available, factor analysis and structural equation modeling could be applied to determine the total imprecision of each biomarker. The estimated imprecision was then applied to adjust benchmark dose calculations and the derived exposure limits. Results The exposure biomarkers correlated well with one another, but the cord blood mercury concentration showed the best associations with neurobehavioral deficits. Factor analysis and structural equation models showed a total imprecision of the cord-blood parameter of 25,30%, and almost twice as much for maternal hair. These imprecisions led to inflated benchmark dose levels. Adjusted calculations resulted in an exposure limit 50% below the level recommended by the U.S. National Research Council. Conclusions The biomarker imprecisions of 25,50% much exceeded normal laboratory variability. Such imprecision causes underestimation of dose-related toxicity and therefore must be considered in the data analysis and when deriving exposure limits. Future studies should ideally include at least three exposure parameters to allow independent assessment of total imprecision. Am. J. Ind. Med. 50:712,719, 2007. © 2007 Wiley-Liss, Inc. [source]

Thimerosal exposure (from tetanus-diphtheria vaccine) during pregnancy and neurodevelopment of breastfed infants at 6 months

ACTA PAEDIATRICA, Issue 6 2010
RC Marques
Abstract Aim:, We studied the effect on neurodevelopment of infants who are exposed to thimerosal in tetanus-diphtheria (Td) vaccines during pregnancy. Methods:, We compared Gesell Developmental Schedules (GDS) of exclusive breastfed infants at 6 months born to mothers who received Td (1 to 3 doses) against those who were born to mothers who did not take such vaccines. Results:, Compared with the group of infants not exposed to ethylmercury in utero, the infants of exposed mothers showed no significant difference in neurodevelopment delays. Although there was a significant correlation between hair-Hg of mothers and hair-Hg of neonates (Spearman r = 0.353; p = 0.0011), there was no significant correlation between the level of in utero exposure to ethylmercury in Td vaccines and neonate's hair-Hg concentrations (Spearman r = 0.060; p = 0.5922). However, regression analysis showed that GDS at 6 months was significantly associated with total mercury concentration of neonate's hair but was not sensitive to the number of vaccines taken by the mother. Conclusion:, Early neurodevelopment of exclusively breastfed infants is sensitive to in utero exposure to mercury, but maternal thimerosal exposure in tetanus-diphtheria vaccines per se cannot portend clinical neurodevelopment delays measured by GDS at 6 months. [source]

Concentrations of selenium and mercury in eared grebes (Podiceps nigricollis) from Utah's great Salt Lake, USA

A nonlethal microsampling technique to monitor the effects of mercury on wild bird eggs

Selenium and mercury concentrations in California gulls breeding on the Great Salt Lake, Utah, USA

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2009
Michael R. Conover
Abstract We examined selenium (Se) and mercury (Hg) concentrations in adult California gulls (Larus californicus) nesting on the Great Salt Lake, Utah, USA, during 2006 and 2007. During 2006, the mean Se concentration (± standard error) was 18.1 ± 1.5 ,g/g in blood on a dry-weight basis and 8.1 ± 0.4 ,g/g in liver. During 2007, Se concentrations were 15.7 ± 1.5 ,g/g in blood and 8.3 ± 0.4 ,g/g in liver; Hg concentrations were 2.4 ± 0.3 ,g/g in blood and 4.1 ± 0.5 ,g/g in liver. Gulls collected from a freshwater colony located within the watershed of the Great Salt Lake had similar levels of Se in the blood and liver as gulls collected on the Great Salt Lake but lower Hg concentrations. Body mass of adult gulls was not correlated with Se or Hg concentrations in their blood or liver. Selenium concentration in California gull eggs collected during 2006 was 3.0 ± 0.10 ,g/g. Of 72 eggs randomly collected from Great Salt Lake colonies, only one was infertile, and none of the embryos exhibited signs of malposition or deformities. We examined 100 newly hatched California gull chicks from Great Salt Lake colonies for teratogenesis; all chicks appeared normal. Hence, the elevated Se and Hg concentrations in adult gulls nesting on the Great Salt Lake did not appear to impair gulls' health or reproductive ability. [source]

High within-individual variation in total mercury concentration in seabird feathers

Influence of feeding ecology on blood mercury concentrations in four species of turtles

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2007
Christine M. Bergeron
Abstract Mercury is a relatively well-studied pollutant because of its global distribution, toxicity, and ability to bioaccumulate and biomagnify in food webs; however, little is known about bioaccumulation and toxicity of Hg in turtles. Total Hg (THg) concentrations in blood were determined for 552 turtles representing four different species (Chelydra serpentina, Sternotherus odoratus, Chrysemys picta, and Pseudemys rubriventris) from a Hg-contaminated site on the South River (VA, USA) and upstream reference sites. Methylmercury and Se concentrations also were determined in a subset of samples. Because the feeding ecology of these species differs drastically, stable isotopes of carbon (,13C) and nitrogen (,15N) were employed to infer the relationship between relative trophic position and Hg concentrations. Significant differences were found among sites and species, suggesting that blood can be used as a bioindicator of Hg exposure in turtles. We found differences in THg concentrations in turtles from the contaminated site that were consistent with their known feeding ecology: C. serpentina , S. odoratus > C. picta > P. rubriventris. This trend was generally supported by the isotope data, which suggested that individual turtles were feeding at more than one trophic level. Methylmercury followed similar spatial patterns as THg and was the predominant Hg species in blood for all turtles. Blood Se concentrations were low in the system, but a marginally positive relationship was found between THg and Se when species were pooled. The blood THg concentrations for the turtles in the present study are some of the highest reported in reptiles, necessitating further studies to investigate potential adverse effects of these high concentrations. [source]

Organochlorine pesticides and mercury in cottonmouths (Agkistrodon piscivorus) from northeastern Texas, USA,

Validity of methyl mercury hair analysis: mercury monitoring in human scalp/nude mouse model

JOURNAL OF APPLIED TOXICOLOGY, Issue 4 2008
Grazyna Zareba
Abstract Objective. The grafting of human scalp hair was used as a new application of this method to explore methyl mercury incorporation into human hair and to validate this model for mercury monitoring in hair. Methods. Human scalp grafts were transplanted to athymic BALB/c nude mice. The animals were exposed to methyl mercury either as a single dose i.p. or continuously for 4 months, using ALZET osmotic pumps. The mercury concentration in hair was determined using x-ray fluorescence (XRF) spectrometry by segmental (2 mm) analysis of a single strand, and tissue concentrations were measured by cold vapor atomic absorption analysis. Results. Human scalp hair grown in nude mice showed long-term persistence of human features including the expression of histocompatibility antigens (KAB 3, W 6/32, SF 1-1.1.1) and normal hair morphometry. The disposition of methyl mercury in nude mice followed a one-compartment model with a whole body elimination half-life of 6.7 days (elimination constant, k = 0.1/day). Autoradiographic studies revealed that methyl mercury was rapidly incorporated into areas of the hair follicle undergoing active keratinization. Methyl mercury concentrations in human hair transplanted onto nude mice were two orders of magnitude higher than in blood and attained a mean hair: blood ratio of 217 : 1, similar to ratios reported only in human studies. Conclusions. This study demonstrated that human hair grown on nude mice can record the level of exposure to methyl mercury and can serve as a valuable research tool to study mercury incorporation into human hair. Copyright © 2007 John Wiley & Sons, Ltd. [source]

MERCURY IN WATER AND SEDIMENT OF STEAMBOAT CREEK, NEVADA: IMPLICATIONS FOR STREAM RESTORATION,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2001
Mitchell Blum
ABSTRACT: The objective of this study was to characterize the sources, concentrations, and distribution of total and methylmercury in water, and channel and bank sediments of Steamboat Creek, Nevada. This information was needed to begin to assess the potential impacts of stream restoration on mercury pollution in this tributary to the Truckee River. The Truckee River flows into Pyramid Lake, a terminal water body home to one endangered and one threatened fish species, where stable pollutants will accumulate over time. Mercury in Steamboat Creek was originally derived from its headwaters, Washoe Lake, where several gold and silver mills that utilized mercury were located. In the 100 plus years since ore processing occurred, mercury-laden alluvium has been deposited in the stream channel and on streambanks where it is available for remobilization. Total mercury concentrations measured in unfiltered water from the creek ranged from 82 to 419 ng/L, with greater than 90 percent of this mercury being particle-bound (> 0.45 (m). Mercury in sediments ranged from 0.26 to 10.2 pg/g. Methylmercury concentrations in sediments of Steamboat Creek were highest in wetlands, lower in the stream channel, and still lower in streambank settings. Methylmercury concentrations in water were 0.63 to 1.4 ng/L. A streambank restoration plan, which includes alterations to channel geometry and wetland creation or expansion, has been initiated for the creek. Data developed indicate that streambank stabilization could reduce the mercury loading to the Creek and that wetland construction could exacerbate methylmercury production. [source]

Using bald eagles to indicate the health of the Great Lakes' environment

LAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 3 2002
William W. Bowerman
Abstract The bald eagle (Haliaeetus leucocephalus) is one of the most studied birds of North America, and a great amount of natural life-history information, including the response of various stressors on the eagles' ability to reproduce, are well known. In Michigan, the eagle has been chosen to track the trends of bioaccumulative compounds of concern across watersheds in the state. The state has been divided into major watersheds, and 20% of these are surveyed each year. A control area in northern Minnesota, Voyageurs National Park, is also sampled annually. We report here on the methods used, the preliminary results of the 1999 field season, and how differences in mercury concentrations varied over a 10-year period. Mercury in feathers of nestling eagles declined over time only in Lakes Michigan and Huron, but have not decreased among other subpopulations in Michigan. Concentrations of polychlorinated biphenyls (PCBs) and 4,4,-DDE in blood plasma from nestling eagles have declined over time for most subpopulations; however, they remain greater for breeding areas associated with the Great Lakes' food web. Sea eagles of the genus Haliaeetus are a good sentinel species to track trends in bioaccumulative compounds in aquatic systems. [source]

Total imprecision of exposure biomarkers: implications for calculating exposure limits

Metallothionein as a biomarker for mercury in tissues of rat fed orally with cinnabar

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 6 2004
Zhi-Yong Huang
Abstract Cinnabar, as one of the most widely used mineral drugs in traditional Chinese medicines, has been proven to have prominent curative effects in clinical use for more than 2000 years. But the safety and toxicity of the drug has been under constant debate in clinic usage. Metallothionein (MT) contains about 30% of cysteine in the molecule, and plays an important detoxification role against heavy metals. In this study, it was used as a biomarker to assess mercurial accumulation in rats fed orally with cinnabar. After feeding rats with cinnabar by gastric gavage at different dosages and at different times, the distribution of heavy metals (including mercury, copper and zinc) and MT was investigated among rat tissues, including liver, kidney, heart, brain, testis and blood. Metals and MT determinations were carried out using inductively coupled plasma mass spectrometry (ICP-MS) and a modified mercury saturation assay technique respectively. The results indicated that mercury was easily accumulated in the tissues of rats exposed to cinnabar, especially in kidney. For example: at a feeding dosage of 5 g kg,1 (bw) for 4 weeks, the mercury concentrations in kidney were 13, 8.7, 21.6 and 26 times those in liver, testis, brain and heart respectively; and at 2.5 g kg,1 (bw) for 2 weeks, the mercury concentrations in kidney were 21, 2.1, 3 and 21 times those in liver, testis, brain and heart respectively. In addition, mercury in kidney and liver of all cinnabar groups was significantly higher than that of the control group (P < 0.01). A high positive correlation observed between MT concentrations and mercury levels in both liver and kidney (R2 = 0.9299, P < 0.02 for liver; R2 = 0.9923, P < 0.0008 for kidney) indicated that MT could be used as a biomarker for mercury in tissues. Copyright © 2004 John Wiley & Sons, Ltd. [source]