Ethylmercury Research Articles

A genome catalogue of mercury‐methylating bacteria and archaea from sediments of a boreal river facing human disturbances

AbstractMethyl mercury, a toxic compound, is produced by anaerobic microbes and magnifies in aquatic food webs, affecting the health of animals and humans. The exploration of mercury methylators based on genomes is still limited, especially in the context of river ecosystems. To address this knowledge gap, we developed a genome catalogue of potential mercury‐methylating microorganisms. This was based on the presence of hgcAB from the sediments of a river affected by two run‐of‐river hydroelectric dams, logging activities and a wildfire. Through the use of genome‐resolved metagenomics, we discovered a unique and diverse group of mercury methylators. These were dominated by members of the metabolically versatile Bacteroidota and were particularly rich in microbes that ferment butyrate. By comparing the diversity and abundance of mercury methylators between sites subjected to different disturbances, we found that ongoing disturbances, such as the input of organic matter related to logging activities, were particularly conducive to the establishment of a mercury‐methylating niche. Finally, to gain a deeper understanding of the environmental factors that shape the diversity of mercury methylators, we compared the mercury‐methylating genome catalogue with the broader microbial community. The results suggest that mercury methylators respond to environmental conditions in a manner similar to the overall microbial community. Therefore, it is crucial to interpret the diversity and abundance of mercury methylators within their specific ecological context.

Machine learning model for depression based on heavy metals among aging people: A study with National Health and Nutrition Examination Survey 2017-2018.

ObjectiveTo explore the association between depression and blood metal elements, we conducted this machine learning model fitting research.MethodsDatasets from the National Health and Nutrition Examination Survey (NHANES) in 2017–2018 were downloaded (https://www.cdc.gov/nchs/nhanes). After screening, 3,247 aging samples with 10 different metals [lead (Pb), mercury (Hg), cadmium (Cd), manganese (Mn), selenium (Se), chromium (Cr), cobalt (Co), inorganic mercury (InHg), methylmercury (MeHg) and ethyl mercury (EtHg)] were included. Eight machine learning algorithms were compared for analyzing metal and depression. After comparison, XGBoost showed optimal effects. Poisson regression and XGBoost model (a kind of decision tree algorithm) were conducted to find the risk factors and prediction for depression.ResultsA total of 344 individuals out of 3247 participants were diagnosed with depression. In the Poisson model, we found Cd (β = 0.22, P = 0.00000941), EtHg (β = 3.43, P = 0.003216), and Hg (β=-0.15, P = 0.001524) were related with depression. XGBoost model was the suitable algorithm for the evaluation of depression, the accuracy was 0.89 with 95%CI (0.87, 0.92) and Kappa value was 0.006. Area under the curve (AUC) was 0.88. After that, an online XGBoost application for depression prediction was developed.ConclusionBlood heavy metals, especially Cd, EtHg, and Hg were significantly associated with depression and the prediction of depression was imperative.

Methyl ethyl mercury poisoning

This datasheet on methyl ethyl mercury poisoning covers Identity, Hosts/Species Affected, Diagnosis.

Risk Factors Analysis of Bone Mineral Density Based on Lasso and Quantile Regression in America during 2015-2018.

This study aimed to explore the risk factors of bone mineral density (BMD) in American residents and further analyse the extent of effects, to provide preventive guidance for maintenance of bone health. A cross-sectional study analysis was carried out in this study, of which data validity was identified and ethics approval was exempted based on the National Health and Nutrition Examination Survey (NHANES) database. Candidates’ demographics, physical examination, laboratory indicators and part of questionnaire information were collected and merged from NHANES in 2015–2016 and 2017–2018. The least absolute shrinkage selection operator (lasso) was used to select initial variables with “glmnet” package of R, quantile regression model to analyze influence factors of BMD and their effects in different sites with “qreg” code in Stata. Among 2937 candidates, 17 covariates were selected by lasso regression (λ = 0.00032) in left arm BMD, with 16 covariates in left leg BMD (λ = 0.00052) and 14 covariates in total BMD (λ = 0.00065). Quantile regression results displayed several factors with different coefficients in separate sites and quantiles: gender, age, educational status, race, high-density lipoprotein (HDL), total cholesterol (TC), lead, manganese, ethyl mercury, smoking, alcohol use and body mass index (BMI) (p < 0.05). We constructed robust regression models to conclude that some demographic characteristics, nutritional factors (especially lipid levels, heavy metals) and unhealthy behaviors affected BMD in varying degrees. Gender and race differences, Low-fat food intake and low exposure to heavy metals (mostly lead, manganese and mercury) should be considered by both clinical doctors and people. There is still no consensus on the impact of smoking and alcohol use on bone mineral density in our study.

Greenhouse Characterization of Inorganic Mercury, Methyl Mercury and Ethyl Mercury Migration and Transformation in Indian Mustard and Chinese Pakchoi

Soil mercury (Hg) contamination has long been a problem that threatens the environment and organisms. Thus, exploring the migration and transformation of Hg from soil to vegetable is vital. In this study, different Hg solutions were employed in greenhouse experiments. The Hg contents in soil and vegetable samples were determined by inductively coupled plasma – mass spectrometry. The results showed that the Hg accumulation depended on its concentration and form. A greater accumulation of inorganic Hg was observed in the roots (2.2–27.4 mg/kg) than in the aerial parts (0.6–6.0 mg/kg). A similar trend was also found in the methyl mercury (MeHg) and ethyl mercury (EtHg) irrigated groups. The MeHg contents were 0.7–8.0 μg/kg in roots and 0.1–3.7 μg/kg in aerial parts. The EtHg concentrations were 0.5–3.3 μg/kg in roots and 0.3–1.1 μg/kg in aerial parts. The translocation factors of inorganic Hg and organic Hg for both vegetables in most treatments were less than 0.5, which suggested that Hg primarily accumulated in the roots. The biological concentration factors of inorganic Hg were less than 0.4, and those for MeHg and EtHg were between 0.4 and 0.95, which indicated that the vegetables were more likely to absorb organic Hg from the soil. The methylation of inorganic Hg occurred in the roots. The potential hazards of Hg on food safety and human health must be considered in regions with serious Hg pollution.

A study on the potential reprotoxic effects of thimerosal in male albino rats.

Thimerosal is ethyl mercury based compound which is being used as a preservative in vaccines since decades. Pharmaceutical products and vaccines that contain thimerosal are among the potential source of mercury exposure. Current research was intended to ascertain the reprotoxic effects of thimerosal on rat testes. Twenty-four adult male albino rats were sorted into four groups (n = 6). The first group was a control group. Rats of experimental Group 2, 3 and 4 were treated with various dosages of thimerosal (0.5, 10, 50 mg/kg) respectively. Rats were decapitated after thirty days of trial and different parameters were analyzed. Thimerosal exposure resulted in a significant decrease in antioxidant enzyme activities including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), glutathione reductase (GSR) and increased levels of thiobarbituric acid reactive substances (TBARS). Different doses of thimerosal significantly decreased (p < 0.05) the concentration of plasma testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH). Additionally, Daily sperm production (DSP) and efficiency of daily sperm production were significantly reduced followed by thimerosal exposure. Moreover, thimerosal significantly (p < 0.05) decreased the primary spermatocytes, secondary spermatocytes, number of spermatogonia along with spermatids. Thimerosal induced adverse histopathological and morphological changes in testicular tissues such as decreased Leydig cells, diameter of seminiferous tubules, tunica albuginea height and epithelial height. On the other hand, the increase in tubular lumen and interstitial spaces was observed due to thimerosal. These outcomes indicated that thimerosal has potential reprotoxic effects in male albino rats.

Determination of mercury species in seafood by liquid chrom tography - inductively coupled plasma mass spectrometry (LC-ICP-MS)

Liquid chromatography hyphenated with inductively coupled plasma mass spectrometry (LC&amp;shy;ICP&amp;shy;MS) was investigated to simultaneously determine three mercury species (mercury methyl mercury and ethyl mercury) in seafood samples. Important parameters such as organic solvents, flow rate of the mobile phase, 2&amp;shy;mercaptoethanol concentration, extraction time and temperature were optimized. The method was validated in term of the limit of detection, limit of quantitation, repeatability, and recovery meeting the AOAC performance requirements. The method has also been validated based on the analysis of certified standard samples DORM&amp;shy;4, then applied to determine three mercury species in 30 seafood samples. Results showed that the content of mercury species was below the maximum limit according to the QCVN 8&amp;shy;2 : 2011/BYT.

Altered antigenicity and immunogenicity of human papillomavirus virus-like particles in the presence of thimerosal

Thimerosal has been widely used as a preservative in human vaccines for decades. Thimerosal, a thiol capping agent with ethyl mercury being the active degradant, could have impacts on the vaccine potency due to potential thiol modification. The effects on the antigenicity and immunogenicity of human papillomavirus (HPV) virus-like particles (VLPs) in the presence of thimerosal was studied. In general, reduced binding activity was observed between HPV antigens and monoclonal antibodies (mAbs) upon thimerosal treatment, accompanied by reduced protein conformational stability. The immunogenicity of a pentavalent vaccine formulation (HPV6, HPV11, HPV16, HPV18 and hepatitis E virus) with or without thimerosal was studied in mice. The functional antibody titres, as well as the binding titres, were determined, showing a substantial decrease for vaccine formulations containing thimerosal for HPV16/18. Similarly, epitope-specific competition assays using specific and functional mAbs as tracers also showed a significant reduction in immunogenicity for HPV16/18 in the presence of thimerosal. Structural alterations in the capsid protein for HPV18 were observed with cryo-electron microscopy and 3-dimensional reconstruction in the comparative structural analysis. The results should alert scientists in formulation development field on the choice for vaccine preservatives, in particular for thiol-containing antigens.

Mercury pollution in modern times and its socio-medical consequences

Mercury plays a critical role in serious health problems due to environmental or occupational exposures. Aquatic ecosystems are an essential component of the global biogeochemical cycle of mercury, as inorganic mercury can be converted to toxic methyl mercury in these environments and reemissions of elemental mercury rival anthropogenic mercury releases on a global scale.The history of the Minamata disease, a typical example of industrial pollution, has shown how corporate secrecy and ignorance on part of the health authorities may influence the devastating spread of environmental contamination and the progress of disease. While the Minamata Convention, in place since 2017, is aiming to lower mercury exposure and to prevent adverse effects, there are still knowledge gaps in the areas of global environmental mercury exposure. Areas of uncertainty in the global biogeochemical cycle of mercury include oxidation processes in the atmosphere, land-atmosphere and ocean-atmosphere cycling, and methylation processes in the ocean. Pollution related to climate change (especially in boreal and arctic regions), bioaccumulation and biomagnification of methyl mercury in the food chain, especially in fish and marine mammals, needs to be addressed in more detail. Information is lacking on numerous hidden contaminant exposures i.e. from globally applied traditional medicine, mercury containing skin creams and soaps, dental amalgam, ethyl mercury containing vaccines and latex paint additives, as well as on mercury releases from power plants, e-waste/fluorescent lamps, wildfire emissions, and global artisanal small-scale gold mining activities.Mercury occurs in various forms with different levels of toxicity. While much is already known and documented on the health effects of mercury, present knowledge and translation into preventive actions is still incomplete. Risks for long term health effects trough prolonged low dose exposure and trough cumulative exposures of various mercury forms should be further addressed. Preventive actions should include adequate human biomonitoring programs. Research data should be translated swiftly into management tools for local policy makers and health professionals, also paying attention at the major differences in mercury contamination across the globe.

The dynamics of mercury near Idrija mercury mine, Slovenia: Horizontal and vertical distributions of total, methyl, and ethyl mercury concentrations in soils

The distributions of the total mercury (T-Hg), methylmercury (MeHg), and ethylmercury (EtHg) concentrations in soil and their relationship to chemical composition of the soil and total organic carbon content (TOC, %) were investigated. Core samples were collected from hill slope on the right and left riverbanks of the Idrija River. Former smelting plant is located on the right bank. The T-Hg average in each of the core samples ranged from 0.25 to 1650 mg kg−1. The vertical T-Hg variations in the samples from the left bank showed no significant change with depth. Conversely, the T-Hg varied with depth, with the surface, or layers several centimeters from the surface, tending to show the highest values in the samples from the right bank. Since the right and left bank soils have different chemical compositions, different pathways of mercury delivery into soils were suggested. The MeHg and EtHg concentrations ranged from n.d. (not detected) to 444 μg kg−1 and n.d. to 17.4 μg kg−1, respectively. The vertical variations of MeHg and EtHg were similar to those of TOC, except for the near-surface layers containing TOC greater than 20%. These results suggest that the decomposition of organic matter is closely related to organic mercury formation.

Speciation of mercury in fish oils using liquid chromatography inductively coupled plasma mass spectrometry

This paper describes a simple and rapid procedure, using liquid chromatography (LC) followed by pneumatic nebulization inductively coupled plasma mass spectrometry (ICP-MS), for the separation and determination of inorganic, methyl, and ethyl mercury compounds. We obtained well-resolved chromatograms within 6min using a reversed-phase C8 column as the stationary phase and a solution containing 0.6% v/v 2-mercaptoethanol and 3% v/v methanol as the mobile phase. We applied this method to the speciation of mercury in several fish oil samples purchased locally. The accuracy of the procedure was verified through the analysis of a reference material (NRCC DOLT-3 Dogfish Liver) certified for both total mercury and methyl mercury. The detection limits of the studied mercury compounds were in the range 0.013–0.026ngHgmL−1 in the injected solutions, corresponding to 0.5–1ngg−1 in the original fish oil samples. Employing a microwave-assisted extraction procedure and the mobile phase solution for the extraction of the mercury compounds, we obtained an extraction efficiency of greater than 89% from the fish oil samples. The recoveries of the individual mercury species added to the samples at 10–25ngHgg−1 were between 93 and 107%. The precision measured between sample replicates was greater than 12% for all determinations.

Liquid chromatography coupled to molecular fluorescence with postcolumn UV sensitization for thimerosal and derivative compounds monitoring in environmental samples.

A HPLC coupled with molecular fluorescence (MF) spectrometry method for determination of thimerosal (THM, sodium ethylmercurythiosalicylate, C9 H9 HgNaO2 S), and derivatives is proposed. A sensitization of MF was provoked by UV irradiation of analytes in a home-made photoreactor that served as interface between the LC column and MF spectrometer. This method is applied to determination of THM, ethyl mercury, and thiosalicylic acid in samples of pharmaceutical industry effluents, and waters of La Carolina and Jáchal rivers situated in the center-west side of San Luis city and in the east of San Juan city (Middle West, Argentine) where the effluents are dumped. The LODs calculated on basis of 3σ criterion were 1.8, 5, and 0.05 μmol/L for THM, ethyl mercury, and for thiosalicylic acid, respectively.

Bioavailability and mobility of mercury in selected soil profiles

To understand the behaviour of mercury in soils and assess the risk of its toxicity, the forms in which the element is found in the environment must be detected. In the occurrence of favourable alkylation conditions (for example in floodplain soils), the content of methyl and ethyl mercury is higher. These Hg forms in comparison with mineral compounds are toxic for the same organisms in concentrations from 10 to 100 times lower. The research concerned eight selected soil profiles representing six different types of soils (Endogleyic Phaeozem, Endogleyic Fluvisol, Eutric Fluvisol, Haplic Luvisols, Brunic Arenosol, Albic Podzol) placed in croplands. The content of mobile (water soluble), available (DTPA-extractable) and bound with organic matter (NaOH-extractable) Hg forms was determined after thermal decomposition using AMA mercury analyser. The mobility as well as availability of mercury in the analysed soils was very low, with average percentage to 0.28 and 2.45 % of the total content of this metal, respectively. It was mainly dependent on texture, the amount of organic matter and soil pH. The percentage of mercury bound with organic matter ranged from 2.34 to 73.70 % of the total content of this metal and was correlated with amount of clay and Fe oxides. Considering these results, the hazard of migration of this element into deeper horizons of the soil profile and ground water is very low. Moreover, crops from the investigated area are not at risk from mercury contamination.

Long-Term Stability of Inorganic, Methyl and Ethyl Mercury in Whole Blood: Effects of Storage Temperature and Time.

In this study, we evaluated the effect of temperature on the long-term stability of three mercury species in bovine blood. We used inductively coupled plasma mass spectrometry (ICP-MS) analysis to determine the concentrations of inorganic (iHg), methyl (MeHg) and ethyl (EtHg) mercury species in two blood pools stored at temperatures of -70, -20, 4, 23°C (room temperature) and 37°C. Over the course of a year, we analyzed aliquots of pooled specimens at time intervals of 1, 2, 4 and 6 weeks and 2, 4, 6, 8, 10 and 12 months. We applied a fixed-effects linear model, step-down pairwise comparison and coefficient of variation statistical analysis to examine the temperature and time effects on changes in mercury species concentrations. We observed several instances of statistically significant differences in mercury species concentrations between different temperatures and time points; however, with considerations of experimental factors (such as instrumental drift and sample preparation procedures), not all differences were scientifically important. We concluded that iHg, MeHg and EtHg species in bovine whole blood were stable at -70, -20, 4 and 23°C for 1 year, but blood samples stored at 37°C were stable for no more than 2 weeks.

Administration of thimerosal-containing vaccines to infant rhesus macaques does not result in autism-like behavior or neuropathology.

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder. Some anecdotal reports suggest that ASD is related to exposure to ethyl mercury, in the form of the vaccine preservative, thimerosal, and/or receiving the measles, mumps, rubella (MMR) vaccine. Using infant rhesus macaques receiving thimerosal-containing vaccines (TCVs) following the recommended pediatric vaccine schedules from the 1990s and 2008, we examined behavior, and neuropathology in three brain regions found to exhibit neuropathology in postmortem ASD brains. No neuronal cellular or protein changes in the cerebellum, hippocampus, or amygdala were observed in animals following the 1990s or 2008 vaccine schedules. Analysis of social behavior in juvenile animals indicated that there were no significant differences in negative behaviors between animals in the control and experimental groups. These data indicate that administration of TCVs and/or the MMR vaccine to rhesus macaques does not result in neuropathological abnormalities, or aberrant behaviors, like those observed in ASD.

State legislations that limit the use of thimerosal in vaccines for pregnant women and their infants

Thimerosal is a mercurial preservative that was widely used in vaccines in the United States and Europe until 2001. By 1999, expanding recommendations for infant vaccinations indicated that United States children who received a complete series of vaccines that contained thimerosal received up to 187.5 μg of ethyl mercury during the first six months of life. This cumulative exposure could exceed the United States Environmental Protection Agency’s recommended safe intake level, estimated in 1997, to be no more than 0.1 μg of mercury per kilogram of body weight per day. This observation lead to a recommendation by the American Academy of Pediatrics that thimerosal is removed to all vaccines that are administered to infants in the United States. Realizing the potential dangers of thimerosal in vaccines, six states have enacted legislations that have limited the amount of thimerosal that can be used in vaccines in their States (Iowa, California, New York, Missouri, Delaware and Washington). In 1987, Congress established the Vaccine Injury Compensation Program to provide compensation to family of individuals who suffer injuries from vaccines. Until recently, these judgments have been paid only to families of non-autistic children who received complications due to the vaccines. In 2008, the Government conceded its first vaccine-autism case in Federal Court. Scientific studies of this autistic child suggested that the autism was related to a mitochondrial disorder. The Federal Government should enact legislation that prohibits the use of thimerosal in vaccines given to pregnant women and their infants.

Ethylmercury and Hg2+ induce the formation of neutrophil extracellular traps (NETs) by human neutrophil granulocytes.

Humans are exposed to different mercurial compounds from various sources, most frequently from dental fillings, preservatives in vaccines, or consumption of fish. Among other toxic effects, these substances interact with the immune system. In high doses, mercurials are immunosuppressive. However, lower doses of some mercurials stimulate the immune system, inducing different forms of autoimmunity, autoantibodies, and glomerulonephritis in rodents. Furthermore, some studies suggest a connection between mercury exposure and the occurrence of autoantibodies against nuclear components and granulocyte cytoplasmic proteins in humans. Still, the underlying mechanisms need to be clarified. The present study investigates the formation of neutrophil extracellular traps (NETs) in response to thimerosal and its metabolites ethyl mercury (EtHg), thiosalicylic acid, and mercuric ions (Hg(2+)). Only EtHg and Hg(2+) triggered NETosis. It was independent of PKC, ERK1/2, p38, and zinc signals and not affected by the NADPH oxidase inhibitor DPI. Instead, EtHg and Hg(2+) triggered NADPH oxidase-independent production of ROS, which are likely to be involved in mercurial-induced NET formation. This finding might help understanding the autoimmune potential of mercurial compounds. Some diseases, to which a connection with mercurials has been shown, such as Wegener's granulomatosis and systemic lupus erythematosus, are characterized by high prevalence of autoantibodies against neutrophil-specific auto-antigens. Externalization in the form of NETs may be a source for exposure to these self-antigens. In genetically susceptible individuals, this could be one step in the series of events leading to autoimmunity.

Ethyl mercury induces Ca2+ uptake through the P2×7 receptor in a mouse cerebellar microglia cell line

Many observations are reported that organic mercury compounds are involved in increasing intracellular Ca2+ levels. However, the issue of which substances on the cell membrane participate in the Ca2+ uptake that is induced by ethyl mercury is unclear. The findings of this study suggest that the P2X receptor participates in this process. The uptake of Ca2+ by C8-B4 cells was induced in the presence of ethyl mercury. Ca channels in the cell membrane were not affected in this process. In contrast, pretreatment with suramin, an antagonist of the P2X receptor, inhibited the Ca2+ uptake induced by ethyl mercury, and also brilliant blue G, a nonselective antagonist of P2×4, P2×5, and P2×7 receptors. In addition, A438079 and A740003, selective antagonists of P2×7 receptor, reduced Ca2+ uptake, while 5-BDBD, a selective antagonist of P2×4 receptor, did not. Furthermore, the mRNAs of both the P2×4 and P2×7 receptors were expressed in the presence of ethyl mercury, but the P2×5 receptor mRNA was not. These findings suggest that ethyl mercury may induce Ca2+ uptake through the P2×7 receptor of the cell membrane.

Total, Methyl, and Ethyl Mercury in the U.S. Population, NHANES 2011-2012

Background: Whole blood measurement of methyl mercury (MeHg), a toxic form of Hg in seafood, has not been technically feasible. Total Hg (THg) has been used as a surrogate, or (MeHg) has been estim...

Total and methyl mercury in whole blood measured for the first time in the U.S. population: NHANES 2011–2012

BackgroundDespite the public health and toxicologic interest in methyl mercury (MeHg) and ethyl mercury (EHg), these mercury species have been technically difficult to measure in large population studies. MethodsUsing NHANES 2011–2012 data, we calculated reference ranges and examined demographic factors associated with specific mercury species concentrations and the ratio of MeHg to THg. We conducted several multiple regression analyses to examine factors associated with MeHg concentrations and also with the ratio of MeHg to THg. ResultsAsians had the highest geometric mean concentrations for MeHg, 1.58µg/L (95% CI 1.29, 1.93) and THg, 1.86µg/L (1.58, 2.19), followed by non-Hispanic blacks with MeHg, 0.52µg/L (0.39, 0.68) and THg, 0.68µg/L (0.54, 0.85). Greater education attainment in adults and male sex were associated with higher MeHg and THg concentrations. Race/ethnicity, age, and sex were significant predictors of MeHg concentrations, which increased with age and were highest in Asians in all age categories, followed by non-Hispanic blacks. Mexican Americans had the lowest adjusted MeHg concentrations. The ratio of MeHg to THg was highest in Asians, varied by racial/ethnic group, and increased with age in a non-linear fashion. The amount of increase in the MeHg to THg ratio with age depended on the initial ratio, with a greater increase as age increased.Of the overall population, 3.05% (95% CI 1.77, 4.87) had MeHg concentrations >5.8µg/L (a value that corresponds to the U.S. EPA reference dose). The prevalence was highest in Asians at 15.85% (95% CI 11.85, 20.56), increased with age, reaching a maximum of 9.26% (3.03, 20.42) at ages 60–69 years. Females 16–44 years old had a 1.76% (0.82–3.28) prevalence of MeHg concentrations >5.8µg/L. ConclusionsAsians, males, older individuals, and adults with greater educational attainment had higher MeHg concentrations. The ratio of MeHg to THg varied with racial/ethnic group, increased with age, and was nonlinear. U.S. population reference values for MeHg and the ratio of MeHg to THg can assist in more precise assessment of public health risk from MeHg consumed in seafood.