Displaying publications 61 - 80 of 114 in total

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  1. Fulltext A new electrochemical sensor based on task-specific ionic liquids-modified palm shell activated carbon for the determination of mercury in water samples
    Abu Ismaiel A, Aroua MK, Yusoff R
    Sensors (Basel), 2014 Jul 21;14(7):13102-13.
    PMID: 25051034 DOI: 10.3390/s140713102
    In this study, a potentiometric sensor composed of palm shell activated carbon modified with trioctylmethylammonium thiosalicylate (TOMATS) was used for the potentiometric determination of mercury ions in water samples. The proposed potentiometric sensor has good operating characteristics towards Hg (II), including a relatively high selectivity; a Nernstian response to Hg (II) ions in a concentration range of 1.0 × 10(-9) to 1.0 × 10(-2) M, with a detection limit of 1 × 10(-10) M and a slope of 44.08 ± 1.0 mV/decade; and a fast response time (~5 s). No significant changes in electrode potential were observed when the pH was varied over the range of 3-9. Additionally, the proposed electrode was characterized by good selectivity towards Hg (II) and no significant interferences from other cationic or anionic species.
    Matched MeSH terms: Mercury/chemistry*
  2. Mercury accumulation in bats near hydroelectric reservoirs in Peninsular Malaysia
    Syaripuddin K, Kumar A, Sing KW, Halim MR, Nursyereen MN, Wilson JJ
    Ecotoxicology, 2014 Sep;23(7):1164-71.
    PMID: 24840106 DOI: 10.1007/s10646-014-1258-y
    In large man-made reservoirs such as those resulting from hydroelectric dam construction, bacteria transform the relatively harmless inorganic mercury naturally present in soil and the submerged plant matter into toxic methylmercury. Methylmercury then enters food webs and can accumulate in organisms at higher trophic levels. Bats feeding on insects emerging from aquatic systems can show accumulation of mercury consumed through their insect prey. In this study, we investigated whether the concentration of mercury in the fur of insectivorous bat species was significantly higher than that in the fur of frugivorous bat species, sampled near hydroelectric reservoirs in Peninsular Malaysia. Bats were sampled at Temenggor Lake and Kenyir Lake and fur samples from the most abundant genera of the two feeding guilds-insectivorous (Hipposideros and Rhinolophus) and frugivorous (Cynopterus and Megaerops) were collected for mercury analysis. We found significantly higher concentrations of total mercury in the fur of insectivorous bats. Mercury concentrations also differed significantly between insectivorous bats sampled at the two sites, with bats from Kenyir Lake, the younger reservoir, showing higher mercury concentrations, and between the insectivorous genera, with Hipposideros bats showing higher mercury concentrations. Ten bats (H. cf. larvatus) sampled at Kenyir Lake had mercury concentrations approaching or exceeding 10 mg/kg, which is the threshold at which detrimental effects occur in humans, bats and mice.
    Matched MeSH terms: Mercury/analysis*
  3. Heavy metals in spices and herbs from wholesale markets in Malaysia
    Nordin N, Selamat J
    Food Addit Contam Part B Surveill, 2013;6(1):36-41.
    PMID: 24786623 DOI: 10.1080/19393210.2012.721140
    As, Cd, Pb and Hg were analysed in commonly consumed spices and herbs in Malaysia. The range of As, Cd, Pb and Hg content was 0.24-2.54, 0.23-8.07, 1.54-8.94 and 0.06-0.52 µg g(-1), respectively. The highest concentration of Cd, Pb and Hg in spices and herbs exceeded the maximum permitted proportion, which are 1, 2 and 0.05 µg g(-1), respectively. This study suggests further monitoring of Cd, Pb and Hg on daily consumption of spices and herbs and its toxicological implication for consumers since only the amount of As was lower than the permitted concentration.
    Matched MeSH terms: Mercury/analysis
  4. Analysis of heavy metal concentrations in sediments of selected estuaries of Malaysia--a statistical assessment
    Alkarkhi AF, Ismail N, Ahmed A, Easa Am
    Environ Monit Assess, 2009 Jun;153(1-4):179-85.
    PMID: 18504644 DOI: 10.1007/s10661-008-0347-x
    Statistical analysis of heavy metal concentrations in sediment was studied to understand the interrelationship between different parameters and also to identify probable source component in order to explain the pollution status of selected estuaries. Concentrations of heavy metals (Cu, Zn, Cd, Fe, Pb, Cr, Hg and Mn) were analyzed in sediments from Juru and Jejawi Estuaries in Malaysia with ten sampling points of each estuary. The results of multivariate statistical techniques showed that the two regions have different characteristics in terms of heavy metals selected and indicates that each region receives pollution from different sources. The results also showed that Fe, Mn, Cd, Hg, and Cu are responsible for large spatial variations explaining 51.15% of the total variance, whilst Zn and Pb explain only 18.93 of the total variance. This study illustrates the usefulness of multivariate statistical techniques for evaluation and interpretation of large complex data sets to get better information about the heavy metal concentrations and design of monitoring network.
    Matched MeSH terms: Mercury/analysis
  5. Optimizing conditions for methylmercury extraction from fish samples for GC analysis using response surface methodology
    Hajeb P, Jinap S, Abu Bakar F, Bakar J
    Food Addit Contam Part A Chem Anal Control Expo Risk Assess, 2009 Jun;26(6):829-38.
    PMID: 19680957 DOI: 10.1080/02652030902751704
    Response surface methodology (RSM) was used to determine the optimum experimental conditions to extract methylmercury from fish samples for GC analysis. The influence of four variables - acid concentration (3-12 M), cysteine concentration (0.5-2% w/v), solvent volume (3-9 ml) and extraction time (10-30 min) - on recovery of methylmercury was evaluated. The detection limit for methylmercury analysis using a microelectron capture detector was 7 ng g(-1) in fish samples. The mean recovery under optimum conditions was 94%. Experimental data were adequately fitted into a second-order polynomial model with multiple regression coefficients (r(2)) of 0.977. The four variables had a significant effect (p < 0.05) on the recovery of methylmercury from a reference material (BCR-463). Optimum conditions for methylmercury extraction were found using an acid concentration of 12.2 M, cysteine concentration of 2.4%, solvent volume of 1.5 ml and extraction time of 35 min. The validation of the developed method to analyze methylmercury in fish samples exhibited good agreement with mercury content in the samples.
    Matched MeSH terms: Mercury/analysis*; Methylmercury Compounds/analysis*
  6. Fulltext Surface plasmon resonance sensing detection of mercury and lead ions based on conducting polymer composite
    Abdi MM, Abdullah LC, Sadrolhosseini AR, Mat Yunus WM, Moksin MM, Tahir PM
    PLoS One, 2011;6(9):e24578.
    PMID: 21931763 DOI: 10.1371/journal.pone.0024578
    A new sensing area for a sensor based on surface plasmon resonance (SPR) was fabricated to detect trace amounts of mercury and lead ions. The gold surface used for SPR measurements were modified with polypyrrole-chitosan (PPy-CHI) conducting polymer composite. The polymer layer was deposited on the gold surface by electrodeposition. This optical sensor was used for monitoring toxic metal ions with and without sensitivity enhancement by chitosan in water samples. The higher amounts of resonance angle unit (ΔRU) were obtained for PPy-CHI film due to a specific binding of chitosan with Pb(2+) and Hg(2+) ions. The Pb(2+) ion bind to the polymer films most strongly, and the sensor was more sensitive to Pb(2+) compared to Hg(2+). The concentrations of ions in the parts per million range produced the changes in the SPR angle minimum in the region of 0.03 to 0.07. Data analysis was done by Matlab software using Fresnel formula for multilayer system.
    Matched MeSH terms: Mercury/chemistry
  7. Biomagnifications of mercury and methylmercury in tuna and mackerel
    Hajeb P, Jinap S, Ahmad I
    Environ Monit Assess, 2010 Dec;171(1-4):205-17.
    PMID: 20041345 DOI: 10.1007/s10661-009-1272-3
    Seawater may be contaminated by harmful substances, including toxic elements released by human activities. The present study evaluates the total mercury and methylmercury concentrations and their correlations to fish body size in longtail tuna and short-bodied mackerel from Chendring, Kuantan, at east coast and Kuala Perlis at west costs of Peninsular Malaysia during May to November 2007. Total mercury and methylmercury in muscle tissue of 69 samples of longtail tuna and short-bodied mackerel, ranged from 0.180 to 1.460 μg/g and 0.0.169-0.973 μg/g and 0.251-1.470 μg/g and 0.202-1.352, whereas the methylmercury to total mercury ratio ranged from 70% to 83%, respectively. Samples of both species from the east coast showed higher levels of mercury compared to those from west coast. In all of the locations, significant positive correlations were found between fish body weight and mercury content (R(2) > 0.470). The estimated weekly intake of total mercury and methylmercury from the consumption 66.33 g/week of short-bodied mackerel and 18.34 g/week of longtail tuna (based on local dietry survey) was found to be lower than the maximum limit of 5 and 1.5 μg/kg bodyweight established by FAO/WHO and codex, respectively.
    Matched MeSH terms: Mercury/analysis*; Methylmercury Compounds/analysis*
  8. Effect of mercury and cadmium on early life stages of Java medaka (Oryzias javanicus): a potential tropical test fish
    Ismail A, Yusof S
    Mar Pollut Bull, 2011;63(5-12):347-9.
    PMID: 21377175 DOI: 10.1016/j.marpolbul.2011.02.014
    Several organisms have been used as indicators, bio-monitoring agents or test organisms in ecotoxicological studies. A close relative of the well established Japanese medaka, the Java medaka (Oryzias javanicus), has the potential to be a test organism. The fish is native to the estuaries of the Malaysian Peninsula, Thailand, Indonesia and Singapore. In this study, newly fertilised eggs were exposed to different concentrations of Cd and Hg. Observations were done on the development of the embryos. Exposure to low levels of Cd and Hg (0.01-0.05 ppm) resulted in several developmental disorders that led to death. Exposure to ≥1.0 ppm Cd resulted in immediate developmental arrest. The embryos of Java medaka showed tolerance to a certain extent when exposed to ≥1.0 ppm Hg compared to Cd. Based on the sensitivity of the embryos, Java medaka is a suitable test organism for ecotoxicology in the tropical region.
    Matched MeSH terms: Mercury/toxicity*
  9. Removal performance of elemental mercury by low-cost adsorbents prepared through facile methods of carbonisation and activation of coconut husk
    Johari K, Alias AS, Saman N, Song ST, Mat H
    Waste Manag Res, 2015 Jan;33(1):81-8.
    PMID: 25492720 DOI: 10.1177/0734242X14562660
    The preparation of chars and activated carbon as low-cost elemental mercury adsorbents was carried out through the carbonisation of coconut husk (pith and fibre) and the activation of chars with potassium hydroxide (KOH), respectively. The synthesised adsorbents were characterised by using scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The elemental mercury removal performance was measured using a conventional flow type packed-bed adsorber. The physical and chemical properties of the adsorbents changed as a result of the carbonisation and activation process, hence affecting on the extent of elemental mercury adsorption. The highest elemental mercury (Hg°) adsorption capacity was obtained for the CP-CHAR (3142.57 µg g(-1)), which significantly outperformed the pristine and activated carbon adsorbents, as well as higher than some adsorbents reported in the literature.
    Matched MeSH terms: Mercury/chemistry*
  10. Fulltext Mercury levels of marine fish commonly consumed in Peninsular Malaysia
    Ahmad NI, Noh MF, Mahiyuddin WR, Jaafar H, Ishak I, Azmi WN, et al.
    Environ Sci Pollut Res Int, 2015 Mar;22(5):3672-86.
    PMID: 25256581 DOI: 10.1007/s11356-014-3538-8
    This study was conducted to determine the concentration of total mercury in the edible portion of 46 species of marine fish (n = 297) collected from selected major fish landing ports and wholesale markets throughout Peninsular Malaysia. Samples were collected in June to December 2009. Prior to analysis, the fish samples were processed which consisted of drying at 65 °C until a constant weight was attained; then, it was grounded and digested by a microwave digestion system. The analytical determination was carried out by using a mercury analysis system. Total mercury concentration among fish species was examined. The results showed that mercury concentrations were found significantly higher (p 20 cm) and were positively related with fish size (length and weight) in all fish samples. Despite the results, the level of mercury in marine fish did not exceed the permitted levels of Malaysian and JECFA guideline values at 0.5 mg/kg methylmercury in fish.
    Matched MeSH terms: Mercury/analysis*; Methylmercury Compounds/analysis*
  11. Potential human health risks from toxic metals via mangrove snail consumption and their ecological risk assessments in the habitat sediment from Peninsular Malaysia
    Cheng WH, Yap CK
    Chemosphere, 2015 Sep;135:156-65.
    PMID: 25950409 DOI: 10.1016/j.chemosphere.2015.04.013
    Samples of mangrove snails Nerita lineata and surface sediments were collected from nine geographical sampling sites in Peninsular Malaysia to determine the concentrations of eight metals. For the soft tissues, the ranges of metal concentrations (μg g(-1) dry weight (dw)) were 3.49-9.02 for As, 0.69-6.25 for Cd, 6.33-25.82 for Cu, 0.71-6.53 for Cr, 221-1285 for Fe, 1.03-50.47 for Pb, and 102.7-130.7 for Zn while Hg as 4.00-64.0 μg kg(-1) dw(-1). For sediments, the ranges were 21.81-59.49 for As, 1.11-2.00 for Cd, 5.59-28.71 for Cu, 18.93-62.91 for Cr, 12973-48916 for Fe, 25.36-172.57 for Pb, and 29.35-130.34 for Zn while for Hg as 2.66-312 μg kg(-1) dw(-1). To determine the ecological risks on the surface habitat sediments, sediment quality guidelines (SQGs), the geochemical indices, and potential ecological risk index (PERI) were used. Based on the SQGs, all the metals investigated were most unlikely to cause any adverse effects. Based on geoaccumulation index and enrichment factor, the sediments were also not polluted by the studied metals. The PERI values based on As, Cd, Cu, Cr, Hg, Pb and Zn in this study were found as 'low ecological risk'. In order to assess the potential health risks, the estimated daily intakes (EDI) of snails were found to be all lower than the RfD guidelines for all metals, except for Pb in some sites investigated. Furthermore, the calculated target hazard quotients (THQ) were found to be less than 1. However, the calculated total target hazard quotients (TTHQ) from all sites were found to be more than 1 for high level consumers except KPPuteh. Therefore, moderate amount of intake is advisable to avoid human health risks to the consumers.
    Matched MeSH terms: Mercury/toxicity
  12. Fulltext An inhibitive enzyme assay to detect mercury and zinc using protease from Coriandrum sativum
    Baskaran G, Masdor NA, Syed MA, Shukor MY
    ScientificWorldJournal, 2013;2013:678356.
    PMID: 24194687 DOI: 10.1155/2013/678356
    Heavy metals pollution has become a great threat to the world. Since instrumental methods are expensive and need skilled technician, a simple and fast method is needed to determine the presence of heavy metals in the environment. In this study, an inhibitive enzyme assay for heavy metals has been developed using crude proteases from Coriandrum sativum. In this assay, casein was used as a substrate and Coomassie dye was used to denote the completion of casein hydrolysis. In the absence of inhibitors, casein was hydrolysed and the solution became brown, while in the presence of metal ions such as Hg²⁺ and Zn²⁺, the hydrolysis of casein was inhibited and the solution remained blue. Both Hg²⁺ and Zn²⁺ exhibited one-phase binding curve with IC₅₀ values of 3.217 mg/L and 0.727 mg/L, respectively. The limits of detection (LOD) and limits of quantitation (LOQ) for Hg were 0.241 and 0.802 mg/L, respectively, while the LOD and LOQ for Zn were 0.228 and 0.761 mg/L, respectively. The enzyme exhibited broad pH ranges for activity. The crude proteases extracted from Coriandrum sativum showed good potential for the development of a rapid, sensitive, and economic inhibitive assay for the biomonitoring of Hg²⁺ and Zn²⁺ in the aquatic environments.
    Matched MeSH terms: Mercury/analysis*
  13. Mercury in dental amalgam: Are our health care workers at risk?
    Sahani M, Sulaiman NS, Tan BS, Yahya NA, Anual ZF, Mahiyuddin WR, et al.
    J Air Waste Manag Assoc, 2016 Nov;66(11):1077-1083.
    PMID: 27192328 DOI: 10.1080/10962247.2016.1188866
    Dental amalgam in fillings exposes workers to mercury. The exposure to mercury was investigated among 1871 dental health care workers. The aim of the study was to evaluate the risk of mercury exposure among dental compared to nondental health care workers and to determine other risk factors for mercury exposure. Respondents answered questionnaires to obtain demographic, personal, professional, and workplace information and were examined for their own amalgam fillings. Chronic mercury exposure was assessed through urinary mercury levels. In total, 1409 dental and 462 nondental health care workers participated in the study. Median urine mercury levels for dental and nondental health care workers were 2.75 μg/L (interquartile range [IQR] = 3.0175) and 2.66 μg/L (IQR = 3.04) respectively. For mercury exposure, there were no significant risk factor found among the workers involved within the dental care. The Mann-Whitney test showed that urine mercury levels were significantly different between respondents who eat seafood more than 5 times per week compared to those who eat it less frequently or not at all (p = 0.003). The urinary mercury levels indicated significant difference between dental workers in their practice using squeeze cloths (Mann-Whitney test, p = 0.03). Multiple logistic regression showed that only the usage of cosmetic products that might contain mercury was found to be significantly associated with the urinary mercury levels (odds ratio [OR] = 15.237; CI: 3.612-64.276). Therefore, mean urinary mercury levels of health care workers were low. Exposure to dental amalgam is not associated with high mercury exposure. However, usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.

    IMPLICATIONS: Exposure to the high levels of mercury from dental amalgam can lead to serious health effects among the dental health care workers. Nationwide chronic mercury exposure among dental personnel was assessed through urinary mercury levels. Findings suggest low urinary mercury levels of these health care workers. Exposure to dental amalgam is not associated with high mercury exposure. However, the usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.
    Matched MeSH terms: Mercury/urine*
  14. Fulltext InSitu Anodization of WO₃-Decorated TiO₂ Nanotube Arrays for Efficient Mercury Removal
    Lee WH, Lai CW, Hamid SBA
    Materials (Basel), 2015 Aug 28;8(9):5702-5714.
    PMID: 28793530 DOI: 10.3390/ma8095270
    WO₃-decorated TiO₂ nanotube arrays were successfully synthesized using an in situ anodization method in ethylene glycol electrolyte with dissolved H₂O₂ and ammonium fluoride in amounts ranging from 0 to 0.5 wt %. Anodization was carried out at a voltage of 40 V for a duration of 60 min. By using the less stable tungsten as the cathode material instead of the conventionally used platinum electrode, tungsten will form dissolved ions (W(6+)) in the electrolyte which will then move toward the titanium foil and form a coherent deposit on the titanium foil. The fluoride ion content was controlled to determine the optimum chemical dissolution rate of TiO₂ during anodization to produce a uniform nanotubular structure of TiO₂ film. Nanotube arrays were then characterized using FESEM, EDAX, XRD, as well as Raman spectroscopy. Based on the FESEM images obtained, nanotube arrays with an average pore diameter of up to 65 nm and a length of 1.8 µm were produced. The tungsten element in the samples was confirmed by EDAX results which showed varying tungsten content from 0.22 to 2.30 at%. XRD and Raman results showed the anatase phase of TiO₂ after calcination at 400 °C for 4 h in air atmosphere. The mercury removal efficiency of the nanotube arrays was investigated by photoirradiating samples dipped in mercury chloride solution with TUV (Tube ultraviolet) 96W UV-B Germicidal light. The nanotubes with the highest aspect ratio (15.9) and geometric surface area factor (92.0) exhibited the best mercury removal performance due to a larger active surface area, which enables more Hg(2+) to adsorb onto the catalyst surface to undergo reduction to Hg⁰. The incorporation of WO₃ species onto TiO₂ nanotubes also improved the mercury removal performance due to improved charge separation and decreased charge carrier recombination because of the charge transfer from the conduction band of TiO₂ to the conduction band of WO₃.
    Matched MeSH terms: Mercury
  15. Characterization of edible bird's nest of different production, species and geographical origins using nutritional composition, physicochemical properties and antioxidant activities
    Quek MC, Chin NL, Yusof YA, Law CL, Tan SW
    Food Res Int, 2018 07;109:35-43.
    PMID: 29803459 DOI: 10.1016/j.foodres.2018.03.078
    Edible bird's nest (EBN) is a precious food made from the solidified saliva of swiftlets. EBN from three types of origin, namely production, swiftlet species and geographical were characterised based on its nutritional composition, physicochemical properties and antioxidant properties. Proximate composition, total phenolic content (TPC) and antioxidant activities were determined following official methods, while mineral and heavy metal contents were obtained by respective atomic adsorption spectrometry (AAS) and inductively coupled plasma-mass spectrometry (ICP-MS). Amino acids profile and sialic acid were determined using high performance liquid chromatography (HPLC). Calcium and sodium were the major elements in EBN samples at averages of 17,267 mg/kg and 13,681 mg/kg, respectively. Despite protein contents were not significantly different; interestingly the total amino acids in A. fuciphagus EBN, 64.57 g/100 g was found to be 23% higher than in A. maximus EBN. EBN from house, A. fuciphagus and Peninsular Malaysia had greater antioxidant activities, 2.33-3.49 mg AAE/g and higher sialic acid, 13.57 g/100 g while those from cave, A. maximus and East Malaysia contained more minerals like calcium and magnesium. The 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and ferric ion reducing antioxidant power (FRAP) of house, A. fuciphagus and Peninsular Malaysia EBNs were approximately 2 times greater than the others. All samples were complied with the Malaysian Standard MS 2334:2011, except for mercury and nitrite. The overall findings suggest that the quality of EBN was varied following the production, species and geographical origins.
    Matched MeSH terms: Mercury
  16. Fulltext Kinetic studies of the partially purified molybdenum-reducing enzyme from Bacillus pumilus strain Lbna
    Abo-Shakeer, L.K.A., Rahman, M.F.A., Yakasai, H., Syed, M.A., Shukor M.Y., Bakar, N.A., et al.
    Bioremediation Science and Technology Research, 2017;5(1):18-23.
    MyJurnal
    Bacterial based remediation of environmental toxicants is a promising innovative technology
    for molybdenum pollution. To date, the enzyme responsible for molybdate reduction to Moblue
    from bacteria show that the Michaelis-Menten constants varies by one order of magnitude.
    It is important that the constants from newer enzyme sources be characterized so that a
    comparison can be made. The aim of this study is to characterize kinetically the enzyme from a
    previously isolated Mo-reducing bacterium; Bacillus pumilus strain Lbna. The maximum
    activity of this enzyme occurred at pH 5.5 and in between 25 and 35 oC. The Km and Vmax of
    NADH were 6.646 mM and 0.057 unit/mg enzyme, while the Km and Vmax of LPPM were 3.399
    mM and 0.106 unit/mg enzyme. The results showed that the enzyme activity for Bacillus
    pumilus strain Lbna were inhibited by all heavy metals used. Zinc, copper, silver, chromium,
    cadmium and mercury all caused more than 50% inhibition to the Mo-reducing enzyme activity
    with copper being the most potent with an almost complete inhibition of enzyme activity
    observed.
    Matched MeSH terms: Mercury
  17. Fulltext Isolation and characterization of a molybdenum-reducing and Orange G-decolorizing Enterobacter sp. strain Zeid-6 in soils from Sudan
    Othman, A.R., Rahman, M.F., Shukor, M.Y., Abu Zeid, I.M., Ariffin, F.
    Bioremediation Science and Technology Research, 2015;3(2):13-19.
    MyJurnal
    Chemical toxins and organic contaminants such as hydrocarbons and dyes are major global
    contaminants with countless tones of those chemicals are created yearly with a significant
    amount release to the environment. In this work we screen the ability of a molybdenum-reducing
    bacterium isolated from contaminated soil to decolorize various azo and triphenyl methane dyes
    independent of molybdenum reduction. Biochemical analysis resulted in a tentative identification
    of the bacterium as Enterobacter sp. strain Zeid-6. The bacterium was able to decolorize the azo
    dye Orange G. The bacterium reduces molybdate to Mo-blue optimally at pH between 5.5 and
    8.0 and temperatures of between 30 and 37 oC. Other requirements include a phosphate
    concentration of 5 mM and a molybdate concentration of 20 mM. The absorption spectrum of the
    Mo-blue produced was similar to previous Mo-reducing bacterium, and closely resembles a
    reduced phosphomolybdate. Molybdenum reduction was inhibited by copper, lead, mercury and
    silver which showed 36.8, 16.9, 64.9 and 67.6% inhibition to Mo-reducing activity of
    Enterobacter sp. strain Zeid-6, respectively. The resultant molybdenum blue spectrum closely
    resembles the spectrum of molybdenum blue from the phosphate determination method. The
    ability of this bacterium to detoxify molybdenum and decolorize azo dye makes this bacterium
    an important tool for bioremediation.
    Matched MeSH terms: Mercury
  18. Fulltext Effective production of keratinase by gellan gum-immobilised Alcaligenes sp. AQ05-001 using heavy metal-free and polluted feather wastes as substrates
    Yusuf I, Ahmad SA, Phang LY, Yasid NA, Shukor MY
    3 Biotech, 2019 Jan;9(1):32.
    PMID: 30622870 DOI: 10.1007/s13205-018-1555-x
    The ability of gellan gum-immobilised cells of the heavy metal-tolerant bacterium Alcaligenes sp. AQ05-001 to utilise both heavy metal-free and heavy metal-polluted feathers (HMPFs) as substrates to produce keratinase enzyme was studied. Optimisation of the media pH, incubation temperature and immobilisation parameters (bead size, bead number, gellan gum concentration) was determined for the best possible production of keratinase using the one-factor-at-a-time technique. The results showed that the immobilised cells could tolerate a broader range of heavy metal concentrations and produced higher keratinase activity at a gellan gum concentration of 0.8% (w/v), a bead size of 3 mm, bead number of 250, pH of 8 and temperature of 30 °C. The entrapped bacterium was used repeatedly for ten cycles to produce keratinase using feathers polluted with 25 ppm of Co, Cu and Ag as substrates without the need for desorption. However, its inability to tolerate/utilise feathers polluted with Hg, Pb, and Zn above 5 ppm, and Ag and Cd above 10 ppm resulted in a considerable decrease in keratinase production. Furthermore, the immobilised cells could retain approximately 95% of their keratinase production capacity when 5 ppm of Co, Cu, and Ag, and 10 ppm of As and Cd were used to pollute feathers. When the feathers containing a mixture of Ag, Co, and Cu at 25 ppm each and Hg, Ni, Pb, and Zn at 5 ppm each were used as substrates, the immobilised cells maintained their operational stability and biological activity (keratinase production) at the end of 3rd and 4th cycles, respectively. The study indicates that HMPF can be effectively utilised as a substrate by the immobilised-cell system of Alcaligenes sp. AQ05-001 for the semi-continuous production of keratinase enzyme.
    Matched MeSH terms: Mercury
  19. Neutron activation analysis and assessment of trace elements in fingernail from residents of Tokyo, Japan
    Wee B, Ebihara M
    Sains Malaysiana, 2017;46:605-613.
    We report herewith the study of fingernail clippings obtained from the residents of Tokyo, Japan. A total of 18 participants with no health problems and occupational exposure to metals were recruited to provide fingernails samples for this study. Through the use of instrumental neutron activation analysis (INAA), 18 elements (Ag, Al, As, Ca, Cl, Co, Cu, Fe, Hg, K, Mg, Mn, Na, S, Sb, Se, V, and Zn) were determined. The results showed that the toxic elements in the fingernails are in the lower range when compared to literature values. There were no chronic exposures to toxic elements such as As and Hg found. The level of Hg found is lower than that reported 20 years ago, possibly due to the strict regulation control in Japan on the release of Hg to the environment. The elements Se and Zn are found to be rather uniformly distributed among participants and are in agreement with results from other countries. There were no significant differences in elemental concentrations due to genders and smoking habits. The overall data from this study showed similar concentrations to those of healthy participants from other countries. Thus, the current data could represent the background level of elemental concentrations in fingernails of residents in Tokyo, which could serve as reference values for future study.
    Matched MeSH terms: Mercury
  20. Fulltext Levels of Mercury in Fish-Eating Children, With and Without Amalgam Restoration
    Padmakumar V, Premkala Raveendran K, Abdulla AM, Ganapathy S, Sainudeen S, Nasim VS, et al.
    J Pharm Bioallied Sci, 2019 May;11(Suppl 2):S397-S401.
    PMID: 31198376 DOI: 10.4103/JPBS.JPBS_44_19
    Background: Mercury is a naturally occurring metal that exists in three forms: elemental (metallic), inorganic, and organic mercury. Amalgam, which is an alloy of inorganic mercury, is used as a restorative material in dentistry. Organic mercury gets ingested in the body mainly by the consumption of seafood. Mercury is also stated to cause various adverse health effects such as gastrointestinal disturbances, dermatitis, muscle weakness, and neurological disorders. In recent years, the use of amalgam has become a controversy stating the various adverse effects of mercury. Hence, the study was conducted to determine and compare the variation in levels of organic and inorganic mercury in fish-eating children before and after placement of amalgam restoration.

    Materials and Methods: Seventy-five subjects, 42 males (56%) and 35 females (44%) of age group ranging 7-13 years, living in South Canara district of Karnataka, India, were selected as a part of the study. Hair and urine samples were collected for estimation of organic and inorganic levels of mercury, respectively. Informed consent was collected from all the participating subjects.

    Results: On comparison between organic and inorganic mercury levels during the study period, the concentration of organic mercury in hair samples was greater irrespective of amalgam restorations present (1.172 and 0.085, respectively; P < 0.001).

    Conclusion: Thus inorganic levels of mercury do not seem to pose a threat as much as the organic levels observed in hair, which remain fairly constant for a longer period of time. Hence in a coastal region where this study was undertaken and fish being a staple food, the risk could probably be attributed to more of an organic toxicity than an inorganic one. Thus amalgam is relatively safe to be practiced and the controversy against it should be reevaluated.

    Matched MeSH terms: Mercury
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