RESUMO
This study used steel slag, fly ash, and metakaolin as raw materials (SFM materials) to create silica-alumina-based geopolymers that can solidify Hg2+ when activated with sodium-based water glass. The experiments began with a triangular lattice point mixing design experiment, and the results were fitted, analyzed, and predicted. The optimum SFM material mass ratio was found to be 70% steel slag, 25% fly ash, and 5% metakaolin. The optimum modulus of the activator was identified by comparing the unconfined compressive strength and solidifying impact on Hg2+of geosynthetics with different modulus. The SFM geopolymer was then applied in the form of potting to cure the granulated mercury tailings. The inclusion of 50% SFM material generated a geosynthetic that reduced mercury transport to the surface soil by roughly 90%. The mercury concentration of herbaceous plant samples was also reduced by 78%. It indicates that the SFM material can effectively attenuate the migration transformation of mercury. Finally, characterization methods such as XPS and FTIR were used to investigate the mechanism of Hg2+ solidification by geopolymers generated by SFM materials. The possible solidification mechanisms were proposed as alkaline environment-induced mercury precipitation, chemical bonding s, surface adsorption of Hg2+ and its precipitates by the geopolymer, and physical encapsulation.
Assuntos
Mercúrio , Mercúrio/química , Mercúrio/análise , Polímeros/química , Poluentes do Solo/química , Poluentes do Solo/análise , Mineração , Cinza de Carvão/química , Modelos QuímicosRESUMO
In present work, blue carbon dots (b-CDs) were derived from ammonium citrate and guanidine hydrochloride, and red carbon dots (r-CDs) were stemmed from malonate, ethylenediamine and mesotetra (4-carboxyphenyl) porphin based on facile hydrothermal method. Eco-friendly ratiometric fluorescence probe was innovatively constructed to effectively measure Hg2+ utilizing b-CDs and r-CDs. The developed probe displayed two typical emission peaks at 450 nm from b-CDs and 650 nm from r-CDs under the excitation at 360 nm. Mercury ion has strong quenching effect on the fluorescence intensity at 450 nm due to the electron transfer process and the fluorescence change at 450 nm was used as the response signal, whereas the fluorescence intensity at 650 nm kept unchangeable which resulted from the chemical inertness between Hg2+ and r-CDs, serving as the reference signal in the sensing system. Under optimal circumstances, this probe exhibited an excellent linearity between the fluorescence response values of ΔF450/F650 and Hg2+ concentrations over range of 0.01-10 µmol/L, and the limit of detection was down to 5.3 nmol/L. Furthermore, this probe was successfully employed for sensing Hg2+ in practical environmental water samples with satisfied recoveries of 98.5%-105.0%. The constructed ratiometric fluorescent probe provided a rapid, environmental-friendly, reliable, and efficient platform for measuring trace Hg2+ in environmental field.
Assuntos
Carbono , Corantes Fluorescentes , Mercúrio , Pontos Quânticos , Poluentes Químicos da Água , Mercúrio/análise , Carbono/química , Corantes Fluorescentes/química , Poluentes Químicos da Água/análise , Pontos Quânticos/química , Monitoramento Ambiental/métodos , Espectrometria de Fluorescência/métodos , Limite de Detecção , FluorescênciaRESUMO
Mercury (Hg) pollution has been a global concern in recent decades, posing a significant threat to entire ecosystems and human health due to its cumulative toxicity, persistence, and transport in the atmosphere. The intense interaction between mercury and selenium has opened up a new field for studying mercury removal from industrial flue gas pollutants. Besides the advantages of good Hg° capture performance and low secondary pollution of the mineral selenium compounds, the most noteworthy is the relatively low regeneration temperature, allowing adsorbent regeneration with low energy consumption, thus reducing the utilization cost and enabling recovery of mercury resources. This paper reviews the recent progress of mineral selenium compounds in flue gas mercury removal, introduces in detail the different types of mineral selenium compounds studied in the field of mercury removal, reviews the adsorption performance of various mineral selenium compounds adsorbents on mercury and the influence of flue gas components, such as reaction temperature, air velocity, and other factors, and summarizes the adsorption mechanism of different fugitive forms of selenium species. Based on the current research progress, future studies should focus on the economic performance and the performance of different carriers and sizes of adsorbents for the removal of Hg0 and the correlation between the gas-particle flow characteristics and gas phase mass transfer with the performance of Hg0 removal in practical industrial applications. In addition, it remains a challenge to distinguish the oxidation and adsorption of Hg0 quantitatively.
Assuntos
Poluentes Atmosféricos , Mercúrio , Mercúrio/química , Adsorção , Poluentes Atmosféricos/química , Selênio/química , Gases/química , Compostos de Selênio/químicaRESUMO
Mercury (Hg), especially methylmercury (MeHg), accumulation in rice grain due to rice paddy possessing conditions conducive to Hg methylation has led to human Hg exposure through consumption of rice-based daily meals. In addition to being a food staple, rice is widely used as a raw material to produce a vast variety of processed food products. Little is known about Hg levels in snacking rice-food products and potential Hg exposure from consumption of them, besides previous studies on infant rice cereals. Aiming to provide complementary information for a more complete assessment on Hg exposure risk originated from Hg-containing rice, this study determined total Hg (THg) and MeHg levels in 195 rice-containing and rice-free processed food products covering all major types of snack foods marketed in China and the estimated daily intake (EDI) of dietary Hg from the consumption of these foods. The results clearly showed THg and MeHg contents in rice-containing foods were significantly higher than rice-free products, suggesting the transfer of Hg and MeHg from the rice to the end products, even after manufacturing processes. Moreover, significant positive correlations were observed between THg, MeHg, or MeHg/THg ratio and rice content for samples containing multiple grains as ingredients, further indicating the deciding role of rice for Hg levels in the end food products. Although the EDI of THg and MeHg via rice-based food products were relatively low compared to the reference dose, it should be considered these snacking food products would contribute additive Hg intake outside of the daily regular meals.
Assuntos
Exposição Dietética , Contaminação de Alimentos , Mercúrio , Compostos de Metilmercúrio , Oryza , Oryza/química , Mercúrio/análise , Contaminação de Alimentos/análise , China , Compostos de Metilmercúrio/análise , Exposição Dietética/análise , Exposição Dietética/estatística & dados numéricos , Humanos , Medição de RiscoRESUMO
In this study, a string of Cr-Mn co-modified activated coke catalysts (XCryMn1-y/AC) were prepared to investigate toluene and Hg0 removal performance. Multifarious characterizations including XRD, TEM, SEM, in situ DRIFTS, BET, XPS and H2-TPR showed that 4%Cr0.5Mn0.5/AC had excellent physicochemical properties and exhibited the best toluene and Hg0 removal efficiency at 200â. By varying the experimental gas components and conditions, it was found that too large weight hourly space velocity would reduce the removal efficiency of toluene and Hg0. Although O2 promoted the abatement of toluene and Hg0, the inhibitory role of H2O and SO2 offset the promoting effect of O2 to some extent. Toluene significantly inhibited Hg0 removal, resulting from that toluene was present at concentrations orders of magnitude greater than mercury's or the catalyst was more prone to adsorb toluene, while Hg0 almost exerted non-existent influence on toluene elimination. The mechanistic analysis showed that the forms of toluene and Hg0 removal included both adsorption and oxidation, where the high-valent metal cations and oxygen vacancy clusters promoted the redox cycle of Cr3+ + Mn3+/Mn4+ â Cr6+ + Mn2+, which facilitated the conversion and replenishment of reactive oxygen species in the oxidation process, and even the CrMn1.5O4 spinel structure could provide a larger catalytic interface, thus enhancing the adsorption/oxidation of toluene and Hg0. Therefore, its excellent physicochemical properties make it a cost-effective potential industrial catalyst with outstanding synergistic toluene and Hg0 removal performance and preeminent resistance to H2O and SO2.
Assuntos
Poluentes Atmosféricos , Mercúrio , Óxidos , Tolueno , Tolueno/química , Óxidos/química , Poluentes Atmosféricos/química , Mercúrio/química , Coque , Catálise , Cromo/química , Adsorção , Manganês/química , Compostos de Manganês/química , Modelos QuímicosRESUMO
Coix lacryma-jobi L. is a traditional medicinal plant in east Asia and is an important crop in Guizhou province, southwest China, where there are elevated levels of soil mercury and arsenic (As). Exposure to multiple potentially toxic elements (PTEs) may affect plant accumulation of metal(loid)s and food safety in regions with high geological metal concentrations. Field experiments were conducted to study the effects of PTEs on metal(loid) accumulation and physiological response of C. lacryma in different plant parts at three pollution levels. Total root length, number of root tips, number of branches, and number of root crosses increased with increasing pollution level, with increases in highly polluted areas of 44.2, 57.0, 79.6, and 97.2%, respectively, compared to lightly polluted areas. Under multi-element stress the activity of C. lacryma antioxidant oxidase showed an increase at low and medium PTE concentrations and inhibition at high concentrations. The As contents were all below the maximum limit of cereal food contaminants in China (GB 2762-2022, As < 0.5 mg kg-1). The stems had high Tl bioconcentration factors but the translocation factors from stem to grain were very low, indicating that the stems may be a key plant part restricting Tl transport to the grains. C. lacryma increased root retention and reduced the transport effect, thus reducing metal accumulation in the grains. C. lacryma adapted to PTE stress through root remodeling and enhanced antioxidant enzyme activities.
Assuntos
Mineração , Poluentes do Solo , Poluentes do Solo/toxicidade , Poluentes do Solo/metabolismo , Raízes de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Solo/química , China , Arsênio/toxicidade , Arsênio/metabolismo , Mercúrio/toxicidade , Mercúrio/metabolismo , Mercúrio/análiseRESUMO
Concentrations of toxic metals (Hg, Pb, and Cd) were determined in the muscles of Lepomis macrochirus, Barbus callensis, and Barbus nasus caught from the Moulouya River of Morocco by graphite furnace (for Pb and Cd) and cold vapour (for Hg) atomic absorption spectrometry, after acid digestion. Although the concentration of metals in some species was relatively high, no health risk has been identified in comparison to the maximum limits as set by the European Commission. The order of increasing concentrations was Cd < Hg < Pb. Calculated Target Hazard Quotients and Hazard Indices were below 1, indicating that the intake of metals via consumption of the muscles of both fish species does not represent a hazard to human health.
Assuntos
Cádmio , Peixes , Contaminação de Alimentos , Chumbo , Mercúrio , Rios , Poluentes Químicos da Água , Marrocos , Animais , Humanos , Chumbo/análise , Cádmio/análise , Mercúrio/análise , Rios/química , Contaminação de Alimentos/análise , Poluentes Químicos da Água/análise , Medição de Risco , Alimentos Marinhos/análise , Metais Pesados/análise , Espectrofotometria Atômica , Monitoramento Ambiental/métodosRESUMO
Processing conditions applied during food production could affect food component contents and bioaccessibility. Here, possible changes in Hg and Se total and species contents and bioaccessibility have been tracked in each stage of the production chain of processed fish-derived products. Therefore, Se:Hg molar ratio and Selenium Health Benefit Value (HBVSe) were calculated for final products and raw materials, resulting favorable in all cases, suggesting the safety of surimi-based products regarding mercury. Speciation studies revealed the presence of SeMeSeCys and SeMet in all samples. Thus, the integrity of the selenium species seems to be maintained. Moreover, in vitro gastrointestinal digestion model evidenced that Se bioaccessibility ranged between 20-39 % for all samples, while in case of Hg was between 8-37 %. Additionaly, SeMeSeCys and SeMet were also identified in the gastrointestinal extracts. Finally, no cytotoxicity was observed after exposure of Caco-2 cells to the gastrointestinal extracts.
Assuntos
Produtos Pesqueiros , Mercúrio , Selênio , Células CACO-2 , Humanos , Selênio/análise , Selênio/toxicidade , Produtos Pesqueiros/análise , Mercúrio/análise , Mercúrio/toxicidade , Mercúrio/metabolismo , Animais , Peixes , Disponibilidade Biológica , Contaminação de Alimentos , Manipulação de Alimentos/métodos , DigestãoRESUMO
The complex sample matrix poses significant challenges in accurately detecting heavy metals. In view of its superior performance for the biological adsorption of heavy metals, probiotic bacteria can be explored for functional unit to eliminate matrix interference. Herein, Lactobacillus rhamnosus (LGG) demonstrates a remarkable tolerance and can adsorb up to 300 µM of Hg2+, following the Freundlich isotherm model with the correlation coefficient (R2) value of 0.9881. Subsequently, by integrating the CRISPR/Cas12a system, a sensitive and specific fluorescent biosensor, "Cas12a-MB," has been developed for Hg2+ detection. Specifically, Hg2+ adsorbed onto LGG can specifically bind to the nucleic acid probe, thereby inhibiting the binding of the probe to LGG and the subsequent activation of the CRISPR/Cas12a system. Under optimal experimental conditions, with the detection time of 90 min and the detection limit of 0.44 nM, the "Cas12a-MB" biosensor offers a novel, eco-friendly approach for Hg2+ detection, showcasing the innovative application of probiotics in biosensor.
Assuntos
Técnicas Biossensoriais , Sistemas CRISPR-Cas , Lacticaseibacillus rhamnosus , Mercúrio , Probióticos , Mercúrio/análise , Mercúrio/química , Técnicas Biossensoriais/métodos , Probióticos/química , Lacticaseibacillus rhamnosus/isolamento & purificação , Lacticaseibacillus rhamnosus/genética , Adsorção , Limite de DetecçãoRESUMO
The main route of human exposure to toxic contaminants is through the consumption of contaminated food. To protect against potential negative health effects of rice consumption, the concentration of total mercury (THg) in rice and rice products sold in Poland was determined, and a consumer risk assessment was carried out. In this study, the concentration of THg in selected types of rice and rice products was determined and assessed. The determinations were carried out using atomic absorption spectroscopy (AAS) in a DMA-1 mercury analyzer. Based on the estimated daily intake (EDI), target hazard quotient values (THQ), and tolerable weekly intake (TWI), the toxicological risk associated with the intake of total mercury and methylmercury (MeHg) from the products tested was also estimated. The analysis indicated that the highest Hg content was in rice cakes and the lowest in white rice and rice noodles. Total mercury content was found to be below the maximum permitted level. The estimated daily intake (EDI) and target hazard quotient (THQ) values for THg and MeHg in rice and rice products were lower than 1. These findings suggest that the food items examined pose no health risk.
Assuntos
Contaminação de Alimentos , Mercúrio , Compostos de Metilmercúrio , Oryza , Oryza/química , Mercúrio/análise , Mercúrio/toxicidade , Humanos , Contaminação de Alimentos/análise , Medição de Risco , Compostos de Metilmercúrio/análise , Compostos de Metilmercúrio/toxicidade , Exposição Dietética , Polônia , Espectrofotometria AtômicaRESUMO
The development of appropriate molecular tools to monitor different mercury speciation, especially CH3Hg+, in living organisms is attractive because its persistent accumulation and toxicity are very harmful to human health. Herein, we develop a novel activity-based ratiometric SERS nanoprobe to selectively monitor Hg2+ and CH3Hg+ in aqueous media and in vivo. In this nanoprobe, a new bifunctional Raman probe bis-s-s'-[(s)-(4-(ethylcarbamoyl)phenyl)boronic acid] (b-(s)-EPBA) was synthesized and immobilized on the surface of gold nanoparticles via a Au-S bond, in which the phenylboronic acid group was employed as the recognition unit for Hg2+ and CH3Hg+ based on the Hg-promoted transmetalation reaction. In the presence of Hg2+ and CH3Hg+, a new surface-enhanced Raman scattering (SERS) peak aroused from of C-Hg appeared at 1080 cm-1, and the SERS intensity at 1002 cm-1 belonged to the B-O symmetric stretching decreased simultaneously. The quantitative tracking of Hg2+ and CH3Hg+ was realized based on the SERS intensity ratio (I1080/I1303) with rapid response (â¼4 min) and high sensitivity, with detection limits of 10.05 and 25.13 nM, respectively. Moreover, the SERS sensor was used for the quantitative detection of Hg2+ and CH3Hg+ in four actual water samples with a high accuracy and excellent recovery. More importantly, cell imaging experiments showed that AuNPs@b-(s)-EPBA could quantitatively detect intracellular CH3Hg+ and had a good concentration dependence in ratiometric SERS imaging. Meanwhile, we demonstrated that AuNPs@b-(s)-EPBA could detect and image CH3Hg+ in zebrafish. We anticipate that AuNPs@b-(s)-EPBA could potentially be used to study the physiological functions related to CH3Hg+ in the future.
Assuntos
Ácidos Borônicos , Ouro , Mercúrio , Nanopartículas Metálicas , Análise Espectral Raman , Análise Espectral Raman/métodos , Ácidos Borônicos/química , Mercúrio/análise , Mercúrio/química , Humanos , Nanopartículas Metálicas/química , Ouro/química , Animais , Peixe-Zebra , Propriedades de Superfície , Água/química , Limite de Detecção , Poluentes Químicos da Água/análiseRESUMO
BACKGROUND: In recent years, environmental pollution has attracted widespread global attention. Among them, environmental problems caused by heavy metal pollution pose a serious threat to human health and ecosystems. Mercury is a common heavy metal pollutant with high toxicity and wide distribution. Excessive intake of Hg2+ can cause permanent and severe damage to the nervous system, respiratory system, and kidneys in the human body. Therefore, developing both accurate and fast detection methods for Hg2+ is of great significance. RESULTS: A sensitive Hg2+ colorimetric sensor is designed based on PtNi nanowires (NWs) and Pt NWs with peroxidase-mimetic activity. PtNi NWs and Pt NWs catalyze the reaction of 3,3', 5,5'-tetramethylbenzidine (TMB) with hydrogen peroxide (H2O2) to produce blue oxidized TMB (oxTMB). The specific interaction of Pt-Hg significantly inhibits the peroxidase-mimetic activity of PtNi NW and Pt NW nanozymes, resulting in a lighter blue color. It is worth noting that compared with specific activity (SA) of Pt NWs (3.31 U/mg), PtNi NWs own superior SA (10.43 U/mg), which inevitably leads to a wider linear range of Hg2+ analysis (1 nM-200 µM) and a lower detection limit (0.6748 nM) for PtNi NWs-based colorimetric sensor, versus linear range (4 nM-5 µM) and LOD of 1.198 nM for Pt NWs-based colorimetric sensor, which are far below the Hg2+ threshold (10 nM) for drinking water set by the US Environmental Protection Agency. SIGNIFICANCE: The two nanozyme colorimetric sensors have been successfully used for the evaluation of Hg2+ in complex river water and tap water. Due to the advantages of simple operation, fast response, and high sensitivity, colorimetric sensors have broad application prospects in environmental monitoring.
Assuntos
Colorimetria , Mercúrio , Nanofios , Níquel , Platina , Mercúrio/análise , Platina/química , Nanofios/química , Níquel/química , Poluentes Químicos da Água/análise , Limite de Detecção , Benzidinas/química , Catálise , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/análiseAssuntos
Rim , Mercúrio , Humanos , Mercúrio/toxicidade , Mercúrio/análise , Rim/efeitos dos fármacos , Rim/patologia , Cosméticos/efeitos adversos , Cosméticos/química , BelezaRESUMO
The development and dissemination of health messaging is a critical component of reducing health disparities. Participants (n = 87) from a human biomonitoring study in six Dene communities responded to a survey about health communication regarding contaminants. The survey included questions on awareness of health messages and risk perceptions related to country foods and contaminants. The vast majority of participants reported eating country foods (99%) and heard that country foods had beneficial nutrients (90%). Seventy per cent of respondents had heard or seen messages about fish with high levels of mercury, and 60% had concerns about the safety or quality of country foods they consumed. Respondents who reported decreasing the number of fish they ate since hearing the messages about fish and mercury had lower (p = 0.04) mercury concentration in hair, compared to those who had not heard the messages. However, no differences in hair mercury were observed for respondents who reported to have changed their fishing location, chosen smaller fish or eaten less predatory fish since hearing the messages. Results indicate the need to examine reasons for self-reported behaviour changes, in addition to awareness. The conclusions of this study can inform the development of messaging and risk management decisions about contaminants within Indigenous populations.
Assuntos
Contaminação de Alimentos , Cabelo , Conhecimentos, Atitudes e Prática em Saúde , Mercúrio , Humanos , Feminino , Masculino , Adulto , Mercúrio/análise , Pessoa de Meia-Idade , Cabelo/química , Contaminação de Alimentos/análise , Territórios do Noroeste , Peixes , Animais , Adulto Jovem , Regiões Árticas , Alimentos Marinhos/análise , Adolescente , IdosoRESUMO
Herein, the selenium (Se) modified gold nanoparticles (Se-AuNPs) was synthesized using cerium doped carbon dots (Ce-CDs) as a reducing agent and template. As desired, Se-AuNPs displays enhanced peroxidase (POD)-like activity in the presence of Hg2+. The mechanism for the enhanced activity was attributed to the increased affinity between Se-AuNPs-Hg2+ and the substrate, in which Se and Au elements have a strong binding capacity to Hg2+, forming Hg-Se bonds and Au-Hg amalgam to generate more ·OH. This POD-like activity of Se-AuNPs-Hg2+ correlates with the colorimetric reaction by the catalytic reaction between 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2. The oxidation of TMB was completely inhibited by the introduction of the reductive S2-. Based on the above findings, a strategy for the colorimetric detection of Hg2+ and S2- by Se-AuNPs was established with linear ranges of 0.33-66 µg/L and 0.625-75 µg/L, and low detection limits of 0.17 µg/L and 0.12 µg/L (3.3 δ/k), respectively. When the colorimetric probes for detection of Hg2+ and S2- was applied in environmental water samples, the recoveries were in the range of 90.3-108.0 %. This method will provide a new idea for the colorimetric detection strategy of Hg2+ due to the strong interaction between Hg and Se.
Assuntos
Colorimetria , Ouro , Mercúrio , Nanopartículas Metálicas , Selênio , Colorimetria/métodos , Mercúrio/análise , Ouro/química , Nanopartículas Metálicas/química , Selênio/química , Limite de Detecção , Poluentes Químicos da Água/análise , Benzidinas/química , Peroxidase/química , Peroxidase/metabolismo , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/análiseRESUMO
Leveraging the fluorescence enhancement effect of the G-triplex (G3)/thioflavin T (ThT) catalyzed by the adjacent double-stranded DNA positioned at the 5' terminus of the G3, the G3-specific oligonucleotide (G3MB6) was utilized to facilitate the rapid detection of mercury (Hg(II)) through thymine-Hg(II)-thymine (T-Hg(II)-T) interactions. G3MB6 adopted a hairpin structure in which partially complementary strands could be disrupted with the presence of Hg(II). It prompted the formation of double-stranded DNA by T-Hg(II)-T, inducing the unbound single strand of G3MB6 to spontaneously form a parallel G3 structure, producing a solid fluorescence signal by ThT. Conversely, fluorescence was absent without Hg(II), since no double strand and formation of G3 occurred. The fluorescence intensity of G3MB6 exhibited a positive correlation with Hg(II) concentrations from 17.72 to 300 nM (R2 = 0.9954), boasting a notably low quality of limitation (LOQ) of 17.72 nM. Additionally, it demonstrated remarkable selectivity for detecting Hg(II). Upon application to detect Hg(II) in milk samples, the recovery rates went from 100.3% to 103.2%.
Assuntos
DNA , Mercúrio , Mercúrio/análise , Mercúrio/química , DNA/química , Animais , Espectrometria de Fluorescência/métodos , Conformação de Ácido Nucleico , Timina/química , Técnicas Biossensoriais/métodos , Leite/químicaRESUMO
INTRODUCTION: Attention-Deficit/Hyperactivity Disorder (ADHD) is a recognized neurodevelopmental disorder with a complex, multifactorial origin. Lead (Pb) and mercury (Hg) are highly toxic substances that can potentially impair brain development and have been implicated in the development of ADHD. This systematic review aims to analyze the epidemiological literature regarding the association between Pb and Hg exposure and the diagnosis of ADHD. METHODS: From November 1983 to June 2, 2023, a comprehensive search was conducted in multiple databases and search engines, including PubMed, Web of Science, Scopus, and Google Scholar. Observational studies (case-control, cohort, and cross-sectional) measuring Pb and Hg levels in various biological samples (blood, hair, urine, nail, saliva, teeth, and bone) of children with ADHD or their parents and their association with ADHD symptoms were included. RESULTS: Out of 2059 studies, 87 met the inclusion criteria and were included in this systematic review. Approximately two-thirds of the 74 studies investigating Pb levels in different biological samples reported associations with at least one subtype of ADHD. However, most studies examining Hg levels in various biological samples found no significant association with any ADHD subtype, although there were variations in exposure periods and diagnostic criteria. CONCLUSION: The evidence gathered from the included studies supports an association between Pb exposure and the diagnosis of ADHD, while no significant association was found with Hg exposure. Importantly, even low levels of Pb were found to elevate the risk of ADHD. Further research is needed to explore the comprehensive range of risk factors for ADHD in children, considering its significance as a neurodevelopmental disorder.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade , Chumbo , Mercúrio , Humanos , Transtorno do Deficit de Atenção com Hiperatividade/epidemiologia , Transtorno do Deficit de Atenção com Hiperatividade/induzido quimicamente , Chumbo/sangue , Chumbo/efeitos adversos , Mercúrio/urina , Mercúrio/sangue , Mercúrio/efeitos adversos , Criança , Exposição Ambiental/efeitos adversosRESUMO
The ecology of the QinghaiâTibet Plateau is fragile, and the ecosystems in the region are difficult to remediate once damaged. Currently, landfilling is the mainstay of domestic waste disposal in China, and numerous, widely distributed county landfills exist. trace elements (TEs) in waste are gradually released with waste degradation and cannot be degraded in nature, affecting environmental quality and human health. To reduce the chance bias that exists in studies of individual landfills, we selected 11 representative county landfills in Tibet, total of 76 soil samples were collected, eight TEs (arsenic (As), mercury (Hg), chromium (Cr), copper (Cu), lead (Pb), cadmium (Cd), nickel (Ni), and zinc (Zn)) were determined, and analysed for the current status of pollution, risk to human health, and sources of TEs to explore the impact of the landfills. The results showed that only a few landfills had individual TEs exceeding the risk screening value of the Soil Environmental Quality Risk Control Standard for Soil Contamination (GB 15618-2018) (pH > 7.5). Most of the soils around the landfills had moderate levels of pollution, but some individual landfills had higher levels, mainly due to Cd and Hg concentrations. Source analysis showed that Hg originated mainly from atmospheric transport; the other TEs came mainly from the weathering of soil parent material and bedrock. The potential risk from TEs to human health was low, and the risk to children was greater than the risk to adults. Among the three exposure routes, oral ingestion resulted in the highest carcinogenic risk and noncarcinogenic risk, with a contribution rate of more than 95%. Among the TEs, Ni had the highest carcinogenic risk, followed by Cr and As, and As had the highest noncarcinogenic risk.
Assuntos
Monitoramento Ambiental , Poluentes do Solo , Solo , Oligoelementos , Instalações de Eliminação de Resíduos , Poluentes do Solo/análise , Tibet , Medição de Risco , Oligoelementos/análise , Solo/química , Humanos , Mercúrio/análise , Metais Pesados/análise , Arsênio/análise , Eliminação de Resíduos , Cádmio/análiseRESUMO
Heavy metals are encountered in nature, and are used in several human endeavors, including in dental fillings. It is well known that the safety of metals depends on their chemical form, as well as the dose and route through which biological systems are exposed to them. Here, we used the Nauphoeta cinerea model to examine the mechanism by which salts of the heavy metals used in dental fillings - silver and mercury - exert their neurotoxicity. Nymphs exposed to heavy metals presented with reduced motor and exploratory abilities as they spent more time immobile, especially in the periphery of a novel object, and covered less distance compared with control nymphs. Exposure to AgNO3 and HgCl2 also exacerbated levels of oxidative stress markers (MDA & ROS) and the neurotransmitter regulators - AChE and MAO, while reducing antioxidant activity markers, both in biochemical (thiol & GST) and RT-qPCR (TRX, GST, SOD, Catalase) examinations, in neural tissues of the cockroach. The observed disruptions in neurolocomotor control, synaptic transmission and redox balance explain how heavy metal salts may predispose organisms to neurological disorders.
Assuntos
Oxirredução , Estresse Oxidativo , Animais , Oxirredução/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Mercúrio/toxicidade , Prata/farmacologia , Prata/toxicidade , Neurotransmissores/metabolismo , Acetilcolinesterase/metabolismo , Ninfa/efeitos dos fármacos , Ninfa/metabolismo , Monoaminoxidase/metabolismo , Comportamento Animal/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Nitrato de Prata/farmacologia , Cloreto de Mercúrio/toxicidadeRESUMO
BACKGROUND: Mercury (Hg) is highly toxic and has the potential to cause severe health problems for humans and foraging animals when transported into edible plant parts. Soil rhizobia that form symbiosis with legumes may possess mechanisms to prevent heavy metal translocation from roots to shoots in plants by exporting metals from nodules or compartmentalizing metal ions inside nodules. Horizontal gene transfer has potential to confer immediate de novo adaptations to stress. We used comparative genomics of high quality de novo assemblies to identify structural differences in the genomes of nitrogen-fixing rhizobia that were isolated from a mercury (Hg) mine site that show high variation in their tolerance to Hg. RESULTS: Our analyses identified multiple structurally conserved merA homologs in the genomes of Sinorhizobium medicae and Rhizobium leguminosarum but only the strains that possessed a Mer operon exhibited 10-fold increased tolerance to Hg. RNAseq analysis revealed nearly all genes in the Mer operon were significantly up-regulated in response to Hg stress in free-living conditions and in nodules. In both free-living and nodule environments, we found the Hg-tolerant strains with a Mer operon exhibited the fewest number of differentially expressed genes (DEGs) in the genome, indicating a rapid and efficient detoxification of Hg from the cells that reduced general stress responses to the Hg-treatment. Expression changes in S. medicae while in bacteroids showed that both rhizobia strain and host-plant tolerance affected the number of DEGs. Aside from Mer operon genes, nif genes which are involved in nitrogenase activity in S. medicae showed significant up-regulation in the most Hg-tolerant strain while inside the most Hg-accumulating host-plant. Transfer of a plasmid containing the Mer operon from the most tolerant strain to low-tolerant strains resulted in an immediate increase in Hg tolerance, indicating that the Mer operon is able to confer hyper tolerance to Hg. CONCLUSIONS: Mer operons have not been previously reported in nitrogen-fixing rhizobia. This study demonstrates a pivotal role of the Mer operon in effective mercury detoxification and hypertolerance in nitrogen-fixing rhizobia. This finding has major implications not only for soil bioremediation, but also host plants growing in mercury contaminated soils.