• Journal of Preventive Medicine and Public Health
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• v.45 no.6
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• pp.353-363
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• 2012

Methylmercury is a hazardous substance that is of interest with regard to environmental health, as inorganic mercury circulating in the general environment is dissolved into freshwater and seawater, condensed through the food chain, ingested by humans, and consequently affects human health. Recently, there has been much interest and discussion regarding the toxicity of methylmercury, the correlation with fish and shellfish intake, and methods of long-term management of the human health effects of methylmercury. What effects chronic exposure to a low concentration of methylmercury has on human health remains controversial. Although the possibility of methylmercury poisoning the heart and blood vessel system, the reproductive system, and the immune system is continuously raised and discussed, and the carcinogenicity of methylmercury is also under discussion, a clear conclusion regarding the human health effects according to exposure level has not yet been drawn. The Joint FAO/WHO Expert Committee on Food Additives proposed to prepare additional fish and shellfish intake recommendations for consumers based on the quantified evaluation of the hazardousness of methylmercury contained in fish and shellfish, methylmercury management in the Korea has not yet caught up with this international trend. Currently, the methylmercury exposure level of Koreans is known to be very high. The starting point of methylmercury exposure management is inorganic mercury in the general environment, but food intake through methylation is the main exposure source. Along with efforts to reduce mercury in the general environment, food intake management should be undertaken to reduce the human exposure to methylmercury in Korea.

• Journal of Soil and Groundwater Environment
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• v.16 no.6
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• pp.122-132
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• 2011

Mercury accumulates in biota mainly as methylmercury. In nature, methylmercury shows high affinity to organic matter and $CH_3Hg^+$-organic matter complexation affects the mobility and bioavailabiity of methylmercury. In this study, we examined the methylmercury binding sites in an aquatic humic acid as affected by the pH condition using Hg $L_{III}$-edge extended X-ray absorption fine structure (EXAFS). We evaluated methylmercury binding humic ligands using methylmercury-thiol, methylmerury-carboxyl, and methylmercury-amine complexation models. When $CH_3Hg^+$-to-humic reduced sulfur ratio is 0.3, we found that most of $CH_3Hg^+$ binds to thiol ligands at pH 5 and 7. At pH 7, however, some carboxyl or amine ligand contribution is observed, unlike at pH 5 where $CH_3Hg^+$ almost exclusively binds to thiol ligands. The carboxyl or amine ligand contribution may indicate that some types of thiol ligands in the natural organic matter have relatively low complexation constants or acid dissociation constants compared to those of some carboxyl or amine ligands. Analysis results indicate that ~0.2 fraction of methylmercury binds to amine or carboxyl ligands and ~0.8 to thiol ligands at pH 7.

• Applied Microscopy
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• v.23 no.1
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• pp.15-24
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• 1993

The toxic effects of methylmercury on the ultrastructures of the brain and gill tissues of fightingfish and compensative effects of red ginseng were investigated by means of electron microscopy. The brain neuron of methylmercury exposure group showed dilatation of dendrite and axon, numerical decrease of ribosomes, partial loss of nucleoplasm and cytoplasm and considerable swelling of mitochondria as compared with the normal neuron. And necrotic cell with ruptured nucleus and vacuolated mitochondria was noticeable. While, slight swelling of mitochondria, some dilation of dendrite and axon and numerical increase of ribosome occurred in the neuron of methylmercury-red ginseng treatment group as compared with the methylmercury exposure group. In the gill lamella of methylmercury exposure group, collapse of pillar cells and arms, dilated epithelial cell and thickened membrane were observed. While, in the gill lamella of methylmercury-red ginseng treatment group, arms were slightly disintegrated and basement membrane was some thickend as compared with the methylmercury exposure group. From the above results, it is concluded that red ginseng has detoxication effect on methylmercury toxicity and so takes compensative effect on injured tissues caused by methylmercury intoxication.

• Bulletin of the Korean Chemical Society
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• v.23 no.12
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• pp.1719-1723
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• 2002

1,5-diphenylcarbazone was immobilized on sodium dodecyl sulfate coated alumina. The alumina particle was effectively used for collection of mercury(II) and methylmercury cations at sub-ppb level. The adsorbed mercury was eluted with l mol $L^{-1}$ of hydrobromic acid solution. The mercury(II) was then directly measured by cold vapor atomic absorption spectrometry utilizing tin (II) chloride where as the total mercury was determined after the oxidation of methylmercury into the inorganic mercury. The methylmercury concentration was calculated by the difference between the value of total mercury and mercury (II). Mercury (II) and methylmercury cations were completely recovered from water with a preconcentration factor of 100 (for 1 L solution.) Relative standard deviation at Hg L ${\mu}gL^{-1}$ level 1.7%(n=8) and the limit of detection was 0.11 ${\mu}gL^{-1}$. The procedure was applied to spring water, well water and seawater and accuracy was assessed through recovery experiments.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.819-823
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• 2008

Mercury and methylmercury concentrations were measured in 225 marine fish samples purchased from retail markets in 5 major Korean cities in 2005. The results showed that the concentrations of mercury and methylmercury ranged from 0.006-0.455 (mean=$0.054{\pm}0.025$) mg/kg and 0.004-0.120 (mean=$0.021{\pm}0.008$) mg/kg, respectively, in fish caught from the coastal waters of the Korean Peninsula. The concentrations in deep-sea fish including tuna ranged from 0.066-2.315 (mean=$0.095{\pm}0.640$) mg/kg for mercury and 0.027-0.897 (mean=$0.281{\pm}0.182$) mg/kg for methylmercury. The estimated weekly intakes (EWIs) of mercury and methylmercury reached 3.92 and 4.70% of the provisional tolerable weekly intakes (PTWI), respectively. Consequently, the levels of mercury and methylmercury in marine fish from current retail markets do not pose any significant health risks for Koreans.

• Proceedings of the Korean Environmental Health Society Conference
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• 2006.06a
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• pp.90-110
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• 2006

In the natural course of events, most human exposure to MeHg is through fish/shellfish consumption. The methylmercury exposure levels depends on the amount and species of fish/shellfish consumed daily. The developing brain in the late gestation period is known to be most vulnerable. Further, more methylmercury accumulates in the fetuses than in mothers. Therefore, efforts must be made to protect the fetuses from the risk of methylmercury, especially in populations which consume a lot of fish/shellfish.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.193-193
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• 2002

Methylmercury causes severe central nervous system disorders. Despite the efforts of many researchers, the mechanisms involved in methylmercury toxicity and the defense against this toxicity remain unknown. We focused on the fact that drug resistance is sometimes involved in elevation of the concentration of the intracellular target of the drug. (omitted)

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.176-176
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• 2003

Methylmercury is known to have devastating effects on the mammalian nervous system. When human neuroblastoma SH-SY5Y cells were treated with methylmercury at sublethal concentrations (6.25 uM), up-regulated genes (39) ＆ down-regulated genes (19) were identified by human 8k cDNA microarray. These genes are related with microtubule process, signal transduction pathway and cell death (apoptosis), Apoptosis-associated genes, HSP70, CDK inhibitor 1, FOS-like antigen were up-regulated and microtubule related genes like villin and dynein down-regultaed. To confirm the presence of apoptosis in cultured SH-SY5Y cells treated 6.25 and 1 uM methylmercury, we applied Annexin V-FITC assay followed by flow cytometric measurements after 6 and 24h. Studies on transcriptional and molecular effect by methylmercury may provide an insight into the neurotoxic effects of methylmercury in human neuronal cells and a possibility to develop more efficient and exact monitoring system of heavy metals as ubiquitous environmental pollutants.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2293-2298
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• 2007

In this study, a dithizone extraction technique involving purge & trap GC-MS was developed for the determination of methylmercury in biological samples, especially blood and fish. After alkaline digestion, methylmercury in biological samples was extracted into dithizone and back-extracted into aqueous sulfide solution. The extracted methylmercury was converted to the volatile ethyl derivative, purged and trapped onto a solid-phase collection medium, and then introduced into the GC-MS system. The determined MDLs of the established method were 0.9 ng·g?1 for biological samples and its accuracy and precision were found to be 93% and 3.8%, respectively. The method was validated by analysis of CRMs such as SRM 966, BCR 463 and IAEA 407 and all analytical results were within certified ranges with average RSDs of less than 6%. The analytical results of field-sampled fish also showed that the method can be successfully used as an alternative for commonly used distillation method followed by GC-CVAFS detection.

• Journal of Plant Biology
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• v.30 no.2
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• pp.109-116
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• 1987

Effects of staining, buffer washing and denaturing agents on the transferrability of RNA fractionated on a methylmercury hydroxide-agarose gel to a nitrocellulose membrane were studied. Ethidium bromide staining and ammonium acetate buffer washing inhibited RNA transfer, while 3% HCHO and 0.5 M NaOH treatments stimulated transfer which was negated in the ammonium acetate buffer. Accordingly, maintenance of primary structure of RNA was proved to be essential for transferring RNA from the methylmercury hydroxideagarose gel to the nitrocellulose membrane.