ABSTRACT
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.
Subject(s)
Humans , Air Pollutants/chemistry , Environmental Exposure , Environmental Restoration and Remediation , Food Chain , Mercury/chemistry , Methylmercury Compounds/chemistry , Photolysis , Sulfur-Reducing Bacteria/metabolism , Water Pollutants, Chemical/metabolismABSTRACT
Mercury is a toxic and non-essential metal in the human body. Mercury is ubiquitously distributed in the environment, present in natural products, and exists extensively in items encountered in daily life. There are three forms of mercury, i.e., elemental (or metallic) mercury, inorganic mercury compounds, and organic mercury compounds. This review examines the toxicity of elemental mercury and inorganic mercury compounds. Inorganic mercury compounds are water soluble with a bioavailability of 7% to 15% after ingestion; they are also irritants and cause gastrointestinal symptoms. Upon entering the body, inorganic mercury compounds are accumulated mainly in the kidneys and produce kidney damage. In contrast, human exposure to elemental mercury is mainly by inhalation, followed by rapid absorption and distribution in all major organs. Elemental mercury from ingestion is poorly absorbed with a bioavailability of less than 0.01%. The primary target organs of elemental mercury are the brain and kidney. Elemental mercury is lipid soluble and can cross the blood-brain barrier, while inorganic mercury compounds are not lipid soluble, rendering them unable to cross the blood-brain barrier. Elemental mercury may also enter the brain from the nasal cavity through the olfactory pathway. The blood mercury is a useful biomarker after short-term and high-level exposure, whereas the urine mercury is the ideal biomarker for long-term exposure to both elemental and inorganic mercury, and also as a good indicator of body burden. This review discusses the common sources of mercury exposure, skin lightening products containing mercury and mercury release from dental amalgam filling, two issues that happen in daily life, bear significant public health importance, and yet undergo extensive debate on their safety.
Subject(s)
Humans , Biological Availability , Biomarkers/blood , Blood-Brain Barrier/metabolism , Body Burden , Dental Amalgam/chemistry , Environmental Exposure , Mercury/chemistry , Mercury Compounds/chemistry , Skin Lightening Preparations/chemistryABSTRACT
OBJECTIVE: The aim of this study was to determine the effect of different hydrogen peroxide concentrations (HP) on mercury and other metal ions release from admixed and spherical dental amalgam. MATERIALS AND METHODS: Dental amalgam discs were prepared from GS.80 and Lojic+ alloys (Southern Dental Industries, Australia) according to manufacturers instructions in stainless steel moulds (10mm diameter and 2mm thickness). The discs (n=25 of each alloy) were divided into five equal groups for each alloy. Each group was immersed in 20 ml of 38%, 24%, 10%, or 3% HP solution for 24 h at 37ºC with 0% (distilled water) as control. Following immersion procedure, solutions were taken for metal ion release determination (Hg, Ag, Sn and Cu) using inductively coupled plasma mass spectrometry (ICP-MS). Statistical analysis was conducted using one and two way ANOVA tests to determine significance of differences between test groups. Bonferroni Post Hoc test was conducted for multiple comparisons. RESULTS: Metal ion release for the elements (Hg, Ag, Sn and Cu) increased with exposure to increasing concentrations of HP for both GS.80 and Lojic+ amalgam alloys. The differences in concentration of metal ions released after treatment with 0% (control), 3%, 10%, 24% or 38% HP were statistically significant (p <0.05). CONCLUSION: Metal ions (Hg, Ag, Cu and Sn) were released from dental amalgam following treatment with all HP concentrations. Metal ion release increased with increasing HP concentration. Even with exposure of dental amalgam to relatively high HP concentration (38%), released Hg did not exceed the maximum acceptable limit.
OBJETIVO: O objetivo deste trabalho foi determinar os efeitos de diferentes concentrações de peróxido de hidrogênio na liberação de íons de Hg e outros metais de amálgamas misturados e esféricos. MATERIAIS E MÉTODOS: Discos de amálgama dental foram preparados com ligas GS.80 e Lojic+, de acordo com instruções dos fabricantes, em moldes de aço inoxidável (10 mm de diâmetro e 2 mm de espessura). Os discos (n=25 de cada liga) foram divididos em cinco grupos iguais para cada liga. Cada grupo foi imerso em 20 ml de solução HP a 38%, 24%, 10% ou 3% a 37ºC, por 24 h a 37ºC, e com água destilada 0% como controle. Após os procedimentos de imersão, soluções foram tomadas para determinação da liberação de íons metálicos (Hg, Ag, Sn and Cu) utilizando-se espectometria da massa de plasma pareadas por indução (ICP-MS). Análise estatística foi conduzida utilizando-se ANOVA testes para determinar significância das diferenças entre os grupos testes. Bonferroni Post Hoc foram feitos para comparações múltiplas. RESULTADOS: A liberação de íons metálicos para os elementos (Hg, Ag, Sn e Cu) aumentou com a exposição a concentrações aumentadas de peróxido de hidrogênio após o tratamento, tanto para a liga de amálgama GS 80 como para aLojic +. As diferenças de concentração dos íons liberados após tratamento com concentrações de peróxido de H a 0%, 3%, 10% ou 38 % foram estatisticamente significantes (p < 0.05). CONCLUSÕES: Íons metálicos (Hg, Ag, Cu e Sn) foram liberados de amálgamas dentais seguindo-se tratamento com todas as concentrações de H2O2. A liberação de ions metálicos aumentou com a elevação da concentração do peróxido de hidrogênio. Mesmo com exposição de amálgama dental a concentrações relativamente altas de peróxido de hidrogênio (38%), a liberação de Hg não excedeu o limite máximo aceitável.
Subject(s)
Dental Amalgam/chemistry , Ions , Mercury/chemistry , Metals/chemistry , Hydrogen Peroxide/chemistry , Tooth Bleaching , Analysis of VarianceABSTRACT
El propósito del presente trabajo es realizar una revisión de diversos estudios sobre la liberación del mercurio de la amalgama dental y su posible toxicidad. Ya se ha medido el mercurio liberado y en teoría no excede los 50 ug diarios. Aunque se le atribuye ser causante de diversas enfermedades, el paciente es la persona menos expuesta a intoxicación, porque el dentista y su higienista o auxiliar es el más expuesto a sufrir las consecuencias de la toxicidad del mercurio
Subject(s)
Humans , Pregnancy , Male , Female , Adult , Middle Aged , Infant, Newborn , Dental Amalgam/toxicity , Mercury/chemistry , Mercury/toxicity , Corrosion , Dentists , Evaporation , Occupational Exposure/adverse effects , Mercury/blood , Mercury/urineABSTRACT
O presente trabalho foi conduzido com a finalidade de estudar os efeitos dos procedimentos de acabamento superficial do amálgama preparado a partir de uma liga convencional (Velvalloy), sobre o conteúdo de mercúrio, topografia e dureza superficial. Foram estabelecidas as seguintes condiçöes: A) brunidura 15 minutos após trituraçäo; B) brunidura após 7 dias; C) brunidura após 15 minutos e polimento após 7 dias; D) polimento após 7 dias; E) brunidura após 7 dias em seguida polimento; F) polimento após 7 dias e em seguida brunidura e G) somente escultura. Os corpos de prova foram preparados da seguinte maneira: (1) para verificaçäo do conteúdo de mercúrio superficial: cavidades circulares foram confeccionadas nas superfícies vestibulares de dentes extraídos...
Subject(s)
Dental Alloys/chemistry , Mercury/chemistry , Dental Polishing/adverse effects , Dental Amalgam/adverse effects , Hardness/drug effects , Dental Materials/chemistry , Dental Restoration, Permanent/adverse effects , TopographyABSTRACT
Com a finalidade de estudar o comportamento clínico de restauraçöes de amálgama, foram preparadas 136 cavidades de classe I, no mínimo duas em cada paciente, pois os procedimentos seriam testados comparativamente, e restauradas com amálgama convencional (Velvalloy). Decorridos 7 dias, as restauraçöes sofreram dois tratamentos superficiais diferentes; uma série de restauraçöes foi polida de maneira convencional e a outra simplesmente brunida. A avaliaçäo foi feita de duas maneiras diferentes: 1) avaliaçäo fotográfica: pares de restauraçöes foram fotografadas inicialmente; posteriormente avaliaçöes de 6 meses e 1 ano foram realizadas, também por fotografias obtidas com câmara Nikkon, aumento de 2 vezes e ampliaçäo final de 7 vezes para a ordenaçäo sequencial...