Determination of methylmercury in urine by direct mercury analyzer / 中华劳动卫生职业病杂志

Objective: To develop asolvent extraction-direct mercury analyzer method for determination of methylmercury in urine. Methods: After the urinehydrolyzesd by hydrobromic acid, methylmercury was extracted by tolueneand reverse-extracted from L-cysteine solution, it was then detectedbydirect mercuryanalyzer. Results: The linear range was 0.2-50.0 μg/L, and the related coefficient was 0.9999. The relative standard deviations (RSD) within the group were 5.04%-6.64%, and the RSD between the group were 5.65%-8.11 %. The average recovery efficiencies were 85.4%-95.5%. The detection limitation was 0.0482 μg/L and the quantification concentrations was 0.1607 μg/L. Conclusion: The method, which has low detection limit, high sensitivity, easy to operate, is stability for the determination of methylmercury in urine.

Role of lysosomal damage in senescence of SH-SY5Y cells induced by methylmercury and intervention of melatonin / 环境与职业医学

Background Methylmercury (MeHg) is a neurotoxin, and melatonin (MT) has a protective effect on the nervous system, but whether it can antagonize MeHg-induced nerve cell damage and the associated mechanism remain unknown. Objective Human neuroblastoma cells (SH-SY5Y cells) were used as research objects. A MeHg-induced SH-SY5Y cell senescence model was established to observe autophagy related protein, lysosomal number, and function changes, as well as potential intervention role and associated mechanism of MT. Methods (1) After SH-SY5Y cells were treated with different doses of MeHg (0, 0.125, 0.25, 0.5, 1, 2, and 4 μmol·L−1) for 48 h, the cell viability was detected using a cell viability detection kit (CCK-8 method) and the viability rate was calculated. Senescent cells were detected by an acidic senescence-associated-β-galactosidase (SA-β-gal) staining. (2) A MeHg dose of 0.5 μmol·L−1 that significantly induced senescence of SH-SY5Y cells was screened, and a half and a quarter of the dose (0.25 and 0.125 μmol·L−1) were used for the middle and low dose groups, respectively. (3) In the MT intervention experiments, SH-SY5Y cells were divided into four groups, including control group (0.1% DMSO), MeHg group (0.5 μmol·L−1 MeHg), MT group (1 mmol·L−1 MT), and MT intervention group (1 mmol·L−1 MT+0.5 μmol·L−1 MeHg). In the MT intervention group, cells were exposed to 0.5 μmol·L−1 MeHg for 48 h after 24 h of 1 mmol·L−1 MT pretreatment. (4) SA-β-gal staining was conducted to observe cell senescence; Western blotting for the expression levels of senescence-associated protein p16, autophagy-associated protein p62, LC3Ⅱ, and lysosomal-associated proteins LAMP1, LAMP2, and TFEB; Lyso-Tracker Red for the quantity of lysosomes; LysoSensor Green DND-189 for lysosomal pH changes; electron microscope for the morphological changes of lysosomes. Results The results of CCK-8 indicated that the viability rate of cells decreased with the increase of MeHg exposure concentration. Compared with the control group, the SA-β-gal positive cell ratio in the 0.5 μmol·L−1 MeHg group increased by 48% (P<0.01), p16, p62, as well as LC3Ⅱ protein expressions were significantly increased (P<0.05), LAMP1 and LAMP2 protein levels, as well as the fluorescence intensities of lysosomal red and green fluorescent probes decreased with the increase of MeHg concentration (P<0.05), and the volume of lysosomes increased under the electron microscope. Compared with the MeHg group, the expression of p16 protein was decreased in the 1 mmol·L−1 MT + 0.5 μmol·L−1 MeHg group and the SA-β-gal positive cell ratio was significantly decreased by 19% (P<0.05), the protein levels of p62 and LC3Ⅱ were significantly decreased, the LAMP1 and LAMP2 protein levels and the fluorescence intensities of lysosomal red and green fluorescent probes were increased respectively, the nuclear entry of TFEB was significantly increased, and the differences were statistically significant (P<0.05). Conclusion MeHg may cause cellular senescence by reducing the number of lysosomes and impairing lysosomal activity in SH-SY5Y cells, and MT may ameliorate MeHg-induced lysosomal abnormalities in SH-SY5Y cells, thereby intervening cell senescence.

Methylmercury toxic mechanism related to protein degradation and chemokine transcription

Methylmercury is an environmental pollutant that causes neurotoxicity. Recent studies have reported that the ubiquitin-proteasome system is involved in defense against methylmercury toxicity through the degradation of proteins synthesizing the pyruvate. Mitochondrial accumulation of pyruvate can enhance methylmercury toxicity. In addition, methylmercury exposure induces several immune-related chemokines, specifically in the brain, and may cause neurotoxicity. This summary highlights several molecular mechanisms of methylmercury-induced neurotoxicity.

Fish consumption, mercury exposure, and the risk of cholesterol profiles: findings from the Korea National Health and Nutrition Examination Survey 2010-2011

In this study, the associations between mercury (Hg) exposure and cholesterol profiles were analyzed, and increased Hg levels and cholesterol profiles according to the amount of fish consumption were evaluated. Data on levels of blood Hg, the frequency of fish consumption, total blood cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) in 3951 adults were obtained from the Korea National Health and Nutrition Examination Survey 2010-2011 database. To compare the distribution for each log-transformed indicator, Student's t-test and analysis of variance were carried out, and the groups were classified according to the frequency of fish consumption through linear regression analysis; the association between Hg level and cholesterol profiles in each group was analyzed. The blood Hg levels (arithmetic mean, median, and geometric mean) for all target participants were 4.59, 3.66, and 3.74 µg/L, respectively. The high cholesterol group, low HDL-C group, and high TG group showed a statistically and significantly higher blood Hg level than the low-risk group. In both sexes, as the frequency of fish consumption increased, blood Hg level also increased, but TC, HDL-C, LDL-C, and TG did not show a similar trend. Increased blood Hg level showed a significant association with increased TC and LDL-C. This statistical significance was maintained in the group with less frequent fish consumption ( < 4 times per month), but the group with frequent fish consumption (>8 times per month) did not show a similar trend. The results of this study suggest that fish consumption increases the level of Hg exposure, and that as the level of Hg exposure increases, the levels of cholesterol profiles increase. However, this study also suggests that the levels of cholesterol profiles in those with frequent fish consumption can be diminished.

Effects of Methylmercury chloride exposure on PKCδ expression in rat developmental cerebellum / 中国免疫学杂志

Objective:To investigate the effect of Methylmercury chloride chronic exposure on PKCδexpression developing cer-ebellum.Methods:Establishment of cerebellum damage model of developmental rats by chronic MMC exposure .In Situ Hybridization and Western blot analysis were performed to detect the expression of PKC isozyme .Results: PKCδ was expressed at high levels at birth, but no significant change was observed with the increase in the time of birth corresponding to brain Hg 2+level, expression of PKCδ in cerebellum of experimental groups was markedly higher than that of control group .Conclusion: Neurotoxicity of Methylmercury chloride exposure might be mediated by PKCδexpression up-regulating in developmental cerebellum .

Developmental neurotoxicity: methylmercury and prenatal exposure protection in the context of the Minamata Convention / Neurotoxicidad durante el desarrollo: metilmercurio y protección frente a la exposición prenatal a este contaminante en el contexto del Convenio de Minamata

Mercury is a global pollutant of public environmental health concern due to its long-range atmospheric distribution, environmental distribution, and neurotoxic effects. Following biological methylation, methylmercury (MeHg) can be un-evenly bioaccumulated within aquatic food chains. Fish consumption can be a significant route of human exposure to MeHg. MeHg exposure in the prenatal stage, at relatively low levels, has recently been established as harmful during neurological development, potentially leading to intellectual disability. The Minamata Convention on Mercury is a global agreement, currently under ratification, to protect human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds. The resolution regarding the role of the World Health Organization and ministries of health in the implementation of the Convention includes protection of human health from critical exposures to MeHg. Riverside populations living in areas with artisanal small-scale gold mining, and relying heavily on fish consumption, have been identified as the most vulnerable population in terms of MeHg exposure and developmental neurotoxicity. This article focuses on the proper design and dissemination of fish advisories within the context of implementation of the Convention.

El mercurio es un contaminante global motivo de preocupación en materia de salud pública ambiental como consecuencia de su amplia distribución atmosférica, su distribución ambiental y sus efectos neurotóxicos. Tras su metilación biológica, el metilmercurio (MeHg) se puede bioacumular de manera desigual en las cadenas alimentarias acuáticas. El consumo de pescado puede ser una ruta significativa de exposición humana al MeHg. Recientemente, se ha establecido que la exposición a niveles relativamente bajos de MeHg en la etapa prenatal es perjudicial para el neurodesarrollo, pudiendo ocasionar discapacidad intelectual. El Convenio de Minamata sobre el Mercurio es un acuerdo a escala mundial, actualmente en fase de ratificación, cuyo objeto es proteger la salud humana y el medio ambiente de las emisiones antropogénicas y los vertidos de mercurio y sus compuestos. La resolución referente a la función de la Organización Mundial de la Salud y los ministerios de salud en la aplicación del Convenio incluye la protección de la salud humana de exposiciones importantes al MeHg. Se ha establecido que las poblaciones ribereñas que residen en zonas de extracción artesanal de oro a pequeña escala, y que dependen en gran medida del consumo de pescado, son las más vulnerables en términos de exposición al MeHg y neurotoxicidad durante el desarrollo. Este artículo se centra en el diseño y la difusión adecuados de las recomendaciones relativas al consumo de pescado en el contexto de la aplicación del Convenio.

Methylmercury inhibits prolactin release in a cell line of pituitary origin

Heavy metals, such as methylmercury, are key environmental pollutants that easily reach human beings by bioaccumulation through the food chain. Several reports have demonstrated that endocrine organs, and especially the pituitary gland, are potential targets for mercury accumulation; however, the effects on the regulation of hormonal release are unclear. It has been suggested that serum prolactin could represent a biomarker of heavy metal exposure. The aim of this study was to evaluate the effect of methylmercury on prolactin release and the role of the nitrergic system using prolactin secretory cells (the mammosomatotroph cell line, GH3B6). Exposure to methylmercury (0-100 μM) was cytotoxic in a time- and concentration-dependent manner, with an LC50 higher than described for cells of neuronal origin, suggesting GH3B6 cells have a relative resistance. Methylmercury (at exposures as low as 1 μM for 2 h) also decreased prolactin release. Interestingly, inhibition of nitric oxide synthase by N-nitro-L-arginine completely prevented the decrease in prolactin release without acute neurotoxic effects of methylmercury. These data indicate that the decrease in prolactin production occurs via activation of the nitrergic system and is an early effect of methylmercury in cells of pituitary origin.

Mercury Exposure in a Riverside Amazon Population, Brazil: A Study of the Ototoxicity of Methylmercury

Introduction Mercury poisoning causes hearing loss in humans and animals. Acute and long-term exposures produce irreversible peripheral and central auditory system damage, and mercury in its various forms of presentation in the environment is ototoxic. Objective We investigated the otoacoustic emissions responses in a riverside population exposed to environmental mercury by analyzing the inhibitory effect of the medial olivocochlear system (MOCS) on transient otoacoustic emissions (TEOAE). Methods The purpose of the research was to evaluate the entire community independently of variables of sex and age. All of the participants were born and lived in a riverside community. After otolaryngologic evaluation, participants were received tympanometry, evaluation of contralateral acoustic reflexes, pure tone audiometry, and recording of TEOAEs with nonlinear click stimulation. Hair samples were collect to measure mercury levels. Results There was no significant correlation between the inhibitory effect of the MOCS, age, and the level of mercury in the hair. Conclusions The pathophysiological effects of chronic exposure may be subtle and nonspecific and can have a long period of latency; therefore, it will be important to monitor the effects of mercury exposure in the central auditory system of the Amazon population over time. Longitudinal studies should be performed to determine whether the inhibitory effect of the MOCS on otoacoustic emissions can be an evaluation method and diagnostic tool in populations exposed to mercury. .

Determination of Methylmercury in Seafood after Dispersive Liquid-liquid Microextraction by Direct Mercury Analyzer / 分析化学

A method for the determination of methylmercury in seafood has been developed using dispersive liquid-liquid microextraction followed by direct mercury analyzer. Total mercury was detected by direct mercury analyzer, and inorganic mercury was calculated by the difference. The parameters affecting the extraction efficiency, including the selection of extractant and dispersant, their volume ratio, concentration of HCl and NaCl have been optimized in this study. The results showed that CH2 Cl2 as extractant, ethanol as dispersant, Volume ration of 1:5, 1 mol/L HCl and 120 g/L NaCl were chosen. The detection limit and the dynamic liner range were 0. 10 μg/L and 0. 2-20 μg/L, respectively. The relative standard deviation was 6. 0% for eleven replicates at the spiked level of 2. 0 μg/L. The enrichment factor was 8. For total Hg determination, the detection limit and the dynamic liner range for methylmercury were 0. 10 μg/kg and 0. 2-50 μg/kg, respectively. The relative standard deviation was 2. 4%. The method was simple, fast and a little solvent needed. Some certified reference materials were analyzed to validate the accuracy of the proposed method, and the results were in good agreement with the reference value. Besides, the method was applied to the real samples with satisfactory results.

Inorganic and Organic Mercury Levels in the United States National Health and Nutrition Examination Survey (NHANES) 2005-2010.

Aims: Mercury is an environmental hazard. Therefore, we studied recent trends in the blood level of organic and inorganic mercury in the United States (US). Methodology: We analyzed newly available data on blood inorganic mercury levels in NHANES 2005-2010. Organic mercury level was calculated by subtracting inorganic mercury level from the total mercury level. As complex sampling was used in NHANES, appropriate weights were used to adjust for oversampling of minorities and sampling from the same location. Results: There were 8364, 8161 and 8727 participants in NHANES 2005-6, 2007-8 and 2009-10 respectively. Inorganic mercury levels (geometric mean [95% confidence intervals]) were 0.31 [0.30-0.32], 0.30 [0.30-0.31], 0.28 [0.27-0.28] μg/L and organic mercury levels were 0.24 [0.19- 0.30], 0.19 [0.14-0.25], 0.27 [0.22-0.33] μg/L in 2005-6, in 2007-8, in 2009-10, respectively. Inorganic mercury levels showed a significant decreasing trend (P<.05). Organic mercury levels were significantly lower in participants aged <20 compared to those ≥20 years. The adjusted proportion (mean±SE) of participants with a total mercury level ≥5.8μg/L was 3.0±0.2%, 3.5±0.6%, and 4.0±0.4% (P<.05) in NHANES 2005-6, 2007-8, and 2009-10, respectively. Conclusions: Inorganic mercury level has been decreasing during the study period. Organic mercury level was lower in 2007-2008 but increased in 2009-10. The significant increase in organic mercury level in the US general population in 2009-10 is of concern, suggesting that continual monitoring of mercury levels is needed.

Mercurio en pescados y su importancia en la salud / Mercury in fish and its importance in health

The contamination of fish with methylmercury (MeHg) could hamper the health promoting properties of fish. Currently, there is strong evidence about the health benefits of seafood consumption. When consumed by the mother before and during pregnancy it improves neurodevelopment of infants and toddlers. Thereafter it reduces the risk of cardiovascular and other chronic diseases. The benefits of fish are mainly due to its content of omega-3 long chain polyunsaturated fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Other constituents, such as high biological value proteins, fat-soluble vitamins, minerals and trace elements contribute to the benefits. On the other hand, there is also convincing evidence about the adverse effects of MeHg on neurodevelopment both during gestation and in early childhood. We herein review the effects of mercury on health. Based on international evidence and new data on the mercury content in Chilean fish, we also propose a recommendation for fish consumption for our population.

Mercúrio e Metilmercúrio em cabelos de crianças e em peixes mais consumidos em Cubatão, Estado de São Paulo, Brasil / Mercury and Methylmercury in the children hair and fish mostly consumed in Cubatão, São Paulo State, Brazil

This study evaluated Hg and MeHg concentrations in fish muscle and children hair from Cubatão, using asstrategies: i) Hg and MeHg determinations in the mostly consumed fish species, ii) Hg and MeHg determinationsin 93 children hair samples (from 04 to 14 years old), and iii) analysis on the children diet consumptionquestionnaire answered by the respective parents. The results obtained in a similar study in Cananeia were usedas references. These two regions show different environmental anthropogenic impacts and distinct eating habits.The quantity and the frequency of fish consumption were the most important factors of Hg bioaccumulation inchildren hair. In both cities, 95 % of mercury contents in hair were >1 mg.kg-1 (US EPA reference) in analyzedchildren, and MeHg were between 67 and 83 % of total Hg. The median for total Hg concentration in fishmuscle (wet basis) ranged from 10 to 179 μg.kg-1 for Cananéia and 10 to 181 μg.kg-1 for Cubatão, values lowerthan the Brazilian limits for Hg in fish. Considering the Hg contents detected in the mostly consumed fish andhair, they indicate that the children are not at risk for Hg and MeHg contamination...

Este estudo avaliou a concentração de Hg e MeHg em amostras de peixes e de cabelos de crianças de Cubatão, usando-se como estratégia: i) Hg total e MeHg em peixes mais consumidos; ii) Hg total e MeHg em cabelos de 93 crianças (04 a 14 anos); iii) análise do inquérito alimentar respondido pelos pais. Os dados obtidos em estudo similar realizado em Cananéia foram usados como referência. Essas duas regiões estuarinas, sob diferentes graus de impacto ambiental, apresentam diferentes hábitos alimentares. A quantidade e a frequência de consumo de peixes foram os fatores mais importantes na bioacumulação de Hg nos cabelos. Em ambas as cidades, 95 % das concentrações de Hg total nos cabelos foram abaixo de 1 mg.kg-1 (limite US EPA) e o percentual de MeHg ocorreu entre 67 e 83 % em relação ao teor de Hg total. As medianas para Hg total nos músculos (base úmida) variaram de 10 a 179 μg.kg-1 para peixes de Cananéia e 10 a 181 μg.kg-1 de Cubatão, inferiores ao limite da legislação brasileira para Hg. A partir dos teores para Hg total e MeHg em peixes mais consumidos e cabelos, as crianças parecem não estar em risco de contaminação...

Determination of Methylmercury and Ethylmercury in Aquatic Products by Gas Chromatography-Mass Spectrometry with Stable Isotope-Labelled Internal Standard / 分析化学

A method for the determination of methylmercury ( MeHg ) and ethylmercury ( EtHg ) in aquatic products was developed using gas chromatography-mass spectrometry with stable isotope-labelled internal standard. After ultrasonication assisted hydrochloric acid extraction, MeHg and EtHg in samples were extracted into toluene under the presence of sodium chloride and then back-extracted into cysteine aqueous solution. The MeHg and EtHg were released from their complexes with cysteine by adding cupric ions, and then derived with sodium tetraphenylborate. Under the optimal chromatographic conditions, MeHgPh and EtHgPh, the resulting derivatives, were separated completely on a DB-5MS capillary column and detected by electron impact ionization mass spectrometry in the selective ion monitoring ( SIM) mode, and quantified by a stable isotope dilution method using the d3-methylmercury as internal standard. The calibration curves were linear in the range of 1-500 μg/L of MeHg and EtHg. Concentration of 0. 828 mg Hg/kg with relative standard deviation ( RSD ) of 3 . 2% ( n=6 ) was obtained for MeHg in GBW 10029 . This was in good agreement with the certified values of (0. 84±0. 03) mg Hg/kg. The average recoveries were 94%-101% and 81%-104% for MeHg and EtHg spiked in aquatic samples, with RSDs of 1. 9%-4. 7% and 3. 1%-8. 2%(n=6), respectively. The limits of detection (S/N=3) of the two targets were 0. 1-0. 3μg/kg. This method was sensitive, accurate and could meet the demand of the determination of methylmercury and ethylmercury in aquatic products.

Toxic effects of methylmercury, arsanilic acid and danofloxacin on the differentiation of mouse embryonic stem cells into neural cells

This study was performed to assess the neurotoxic effects of methylmercury, arsanilic acid and danofloxacin by quantification of neural-specific proteins in vitro. Quantitation of the protein markers during 14 days of differentiation indicated that the mouse ESCs were completely differentiated into neural cells by Day 8. The cells were treated with non-cytotoxic concentrations of three chemicals during differentiation. Low levels of exposure to methylmercury decreased the expression of GABAA-R and Nestin during the differentiating stage, and Nestin during the differentiated stage. In contrast, GFAP, Tuj1, and MAP2 expression was affected only by relatively high doses during both stages. Arsanilic acid affected the levels of GABA(A)-R and GFAP during the differentiated stage while the changes of Nestin and Tuj1 were greater during the differentiating stage. For the neural markers (except Nestin) expressed during both stages, danofloxacin affected protein levels at lower concentrations in the differentiated stage than the differentiating stage. Acetylcholinesterase activity was inhibited by relatively low concentrations of methylmercury and arsanilic acid during the differentiating stage while this activity was inhibited only by more than 40 microM of danofloxacin in the differentiated stage. Our results provide useful information about the different toxicities of chemicals and the impact on neural development.

Exposição aguda ao Metilmercúrio em ratos em desenvolvimento: mini-revisão / Acute exposition of developing rats to Methylmercury: a mini-review

Mercúrio (Hg) está presente no ambiente em três diferentes formas químicas: elementar (Hg0), inorgânico e orgânico, sendo que a sua distribuição, toxicidade e metabolismo são dependentes de sua forma química. A exposição oral ao consumo de peixes e alimentos contaminados é a principal forma de exposição humana ao metilmercúrio (MeHg), um poluente ambiental que é absorvido por ingestão, inalação e através da pele. O MeHg é um potente neurotóxico, especialmente para o cérebro em desenvolvimento. Neste estudo, foram examinados os principais efeitos da exposição ao MeHg durante o desenvolvimento salientando os mecanismos bioquímicos envolvidos nestes processos. Também foram apresentados recentes resultados sobre o uso de extratos de plantas medicinais que atenuaram os efeitos adversos deste metal. Deste modo, estes dados reforçam a toxicidade do MeHg durante o desenvolvimento e sugerem possíveis caminhos para futuras intervenções terapêuticas.

Mercury (Hg) is present in the environment in three different chemical forms: elemental, inorganic and organic Hg. The distribution, toxicity and metabolism of Hg are linked to its chemical form. The oral exposition following fish and food contaminated is the main route of contamination of humans to the methilmercury (MeHg), an environmental pollutant which is absorbed by ingestion, inhalation and through the skin. MeHg is a strong neurotoxic molecule, especially for the developing brain. In this study, the main effects of the MeHg exposition and the biochemical parameters involved in this process were examined. The results of the use of plant extracts which attenuate the adverse effects of this metal are also presented here. Therefore, these data reinforce the MeHg toxicity during the development and suggest alternative ways for future therapeutic approaches.

Effects of methylmercury on electric organ discharges in the weak electric fish Gymnotus sylvius

Methylmercury (MeHg) is present in the environment because of natural and anthropogenic causes. MeHg can reach the central nervous system (CNS) and cause neurological damage in humans and animals. Electric organ discharges (EODs) in the weak electric fish Gymnotus sylvius are produced by the electric organ and modulated by the CNS. These discharges are used for electrolocation and communication. The purpose of the present study was to investigate the effects of dietary MeHg exposure on EOD rate in G. sylvius. An oscilloscope was used to record the EOD rate. Two treatments were investigated: chronic MeHg administration (4 µg/kg MeHg every 2 days, with a total of nine dietary exposures to MeHg) and acute MeHg administration (a single dose of 20 µg/kg MeHg). The control data for both treatments were collected every 2 days for 18 days, with a total of nine sessions (day 1 until day 18). Data of fish exposed to MeHg were collected every 2 days, totaling nine sessions (day 19 until day 36). Chronic treatment significantly increased the EOD rate in G. sylvius (p < .05), especially with the final treatment (day 32 until day 36). Acute treatment resulted in an initial increase in the EOD rate, which was maintained midway through the experiment (day 26 until day 30; p < .05). The present study provides the first insights into the effects of MeHg on EODs in weak electric fish. The EOD rate is a novel response of the fish to MeHg administration.

Four Cases of Abnormal Neuropsychological Findings in Children with High Blood Methylmercury Concentrations

BACKGROUND: Methylmercury (MeHg) easily crosses the blood-brain barrier and accumulates in the brain. Accumulated MeHg will cause neurological symptoms. We report four pediatric cases of neuropsychological findings with high blood MeHg concentrations. CASE PRESENTATION: Four children were admitted for follow-up study because their total mercury (THg) concentration in the blood was found to be high during a national survey. Case 1 was a 9-year-old female with a 16.6 microg/l blood THg concentration in the survey. During admission, the blood THg, hair THg, and blood MeHg concentration(mercury indices) were 21.4 microg/l, 7.2 microg/g, and 20.1 microg/l, respectively. In our neuropsychological examination, cognitive impairment and attention deficit were observed. Her diet included fish intake 2-3 times per week, and she had been diagnosed with epilepsy at 3 years of age. Case 2 was a 12-year-old male with blood THg of 15.4 microg/l in the survey and the mercury indices were 12.7 microg/l, 5.7 microg/g, and 11.8 microg/l, respectively, on admission. He was also observed to have attention-deficit/hyperactivity disorder. Case 3 was a 10-year-old male child with blood THg of 17.4 microg/l in the survey, and the mercury indices on admission were 21.6 microg/l, 7.5 microg/g and 21.5 microg/l, respectively. In his case, mild attention deficit was observed. Case 4 was a 9-year-old male with blood THg of 20.6 microg/l in the survey and the mercury indices were 18.9 microg/l, 8.3 microg/g, and 14.4 microg/l, respectively, on admission. Mild attention difficulty was observed. CONCLUSION: We suggest that fish consumption may be the main source of MeHg exposure, and that MeHg may have been the cause of the neuropsychological deficits in these cases.

Mercury and methylmercury concentration assessment in children's hair from Manaus, Amazonas state, Brazil / Avaliação da concentração de mercúrio e metilmercúrio em cabelo de crianças de Manaus, estado do Amazonas, Brasil

The present study evaluated Hg and MeHg content in hair samples of 201 children 2 to 7 years old, living in six neighborhoods of the city of Manaus, Amazonas State, Brazil. In general, the total Hg and MeHg median ranges in hair were similar (0.91 to 1.71 mg kg-1) except for the São Jose neighborhood, which was lower (0.16 mg kg-1). De spite the fact that the Manaus population consumes fish as part of the normal dietary intake, the Hg hair levels were below the level for an adult population not exposed to mercury (2.0 mg kg-1). These data were compared to demographic, socioeconomic information and eating habits of the families that took part in the study. The results were also compared to other published data from the Amazon region, other regions of Brazil and other countries. Future studies to set Hg and MeHg levels in hair of children in Brazil should take into account and assess the diversity of the country, mainly in terms of eating habits, socio-economic and cultural aspects.

O presente estudo avaliou o teor de Hg e MeHg em amostras de cabelo de 201 crianças de 2 aos 7 anos de idade, residentes em seis bairros da cidade de Manaus, Amazonas, Brasil. Em geral, o teor de Hg total e MeHg em cabelo foram semelhantes (medianas de 0,91 a 1,71 mg kg-1), exceto para o bairro São José, que foi menor (0,16 mg kg-1). Apesar da população de Manaus consumir peixe como parte da dieta normal, os níveis de Hg nos cabelos ficaram abaixo do nível para uma população adulta não exposta ao mercúrio (2,0 mg kg-1). Esses dados foram comparados com informações demográficas, socioeconômicas e hábitos alimentares das famílias que participaram do estudo. Os resultados também foram comparados com outros dados publicados da Amazônia, outras regiões do Brasil e outros países. Futuros estudos para definir os níveis de Hg total e MeHg no cabelo das crianças brasileiras deverão considerar e avaliar a diversidade do país, principalmente em termos de hábitos alimentares, nível sócio-econômico e os aspectos culturais.

Analysis on heavy metal pollution in major seafoods from Zhoushan Fishery, China / 中华流行病学杂志

Objective Through reviewing data on surveys,tested materials especially on lead in Zhoushan fisheries,with ground lead,cadmium and methyl-mercury were analyzed and evaluated.Methods According to the distribution of Zhoushan fisheries,we randomly selected a certain number of Zhoushan seafood as research objects from four counties or districts.Different kinds of seafood would include sea fish,seawater crustaceans,seawater soft-bodied animals and sea algae.The inedible parts of all the seafood were removed,and then the samples of the edible parts were grinded into homogenate.We measured the contents of lead and cadmium,using graphite furnace atomic absorption spectrometry method.The content of methylmercury was measured,using the gas chromatography (acid extraction method of mercaptoacetic cotton).Data from 2007 to 2009 was analyzed under SPSS software.Results (1)The average standardized rates were:lead as 3.90％ (11/282),cadmium as 11.35％ (32/282) and methylmercury as 2.84％ (8/282).(2) Results from the comprehensive evaluation on the contents of metals showed the following rankings:seaweed (0.4513 mg/kg),marine molluscs (0.1155 mg/kg),marine crustaceans (0.0486 mg/kg),sea-fish (0.0419 mg/kg).(3) Results from the single-factor variance analysis showed that the accumulation of lead,cadmium and methylmercury in different types of seafood were:lead F=35.683 (P＜0.001) ;cadmium F=25.301 (P＜0.001) ; methylmercury F=25.990 (P＜0.001).(4) Data on the safety analysis related to the different types of seafood on lead,cadmium,methylmercury food,the Chisquare tests showed as:lead x2=10.167,P＜0.05 ; cadmium x2=62.940,P＜0.001 ; methylmercury x2=20.960,P＜0.001.(5) Seafood in different years on lead,cadmium,methylmercury accumulation comparison,the Spearman correlation test results showed:lead P=0.000,cadmium P=0.974,methylmercury P=0.024.(6) The contents of seafood lead,cadmium and methylmercury in different years that with statistically significant differences were as follows:lead x2=6.440,P＜0.05; cadmium x2=34.455,P＜0.001 ;methylmercury x2=5.226,P＞0.05.Conclusion The situation of heavy metal pollution in different kinds of Zhoushan fisheries was different.Algae appeared the worst while sea fish,sea water crustaceans pollution were light,with lead and methylmercury mainly influencing sea algae and cadmium mainly in the sea algae,followed by seawater software class.The rates over standards of different kinds of seafood were different from each other,while the rates over standards of lead,cadmium and methylmercury in sea algae were the highest.Evaluated by pollution index,lead,methylmercury pollution was still low,but cadmium in the sea with mild pollution in algae seafood.In the recent three years,heavy metal lead pollution in seafood were worsened,while the cadmium,methylmercury pollution levels remained basically stable.

Fate and Transport of Mercury in Environmental Media and Human Exposure / 예방의학회지

Mercury is emitted to the atmosphere from various natural and anthropogenic sources, and degrades with difficulty in the environment. Mercury exists as various species, mainly elemental (Hg0) and divalent (Hg2+) mercury depending on its oxidation states in air and water. Mercury emitted to the atmosphere can be deposited into aqueous environments by wet and dry depositions, and some can be re-emitted into the atmosphere. The deposited mercury species, mainly Hg2+, can react with various organic compounds in water and sediment by biotic reactions mediated by sulfur-reducing bacteria, and abiotic reactions mediated by sunlight photolysis, resulting in conversion into organic mercury such as methylmercury (MeHg). MeHg can be bioaccumulated through the food web in the ecosystem, finally exposing humans who consume fish. For a better understanding of how humans are exposed to mercury in the environment, this review paper summarizes the mechanisms of emission, fate and transport, speciation chemistry, bioaccumulation, levels of contamination in environmental media, and finally exposure assessment of humans.