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Journal of Trace Elements in Medicine... Mar 2019The mercury-related central nervous system disorders have been extensively studied on animal models and human beings. However, clinical evidences of which neurological...
The mercury-related central nervous system disorders have been extensively studied on animal models and human beings. However, clinical evidences of which neurological changes are in fact associated with mercury exposure remains controversial. This systematic review (Prospero registration under the number CRD42016041760) aimed to elucidate the association of methylmercury (MeHg) exposure with neurological alteration in populations living in MeHg-endemic risk area. A systematic search was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis criteria using available databases PubMed, LILACS, Scopus, Web of Science, The Cochrane Library, OpenGrey and Google Scholar. A search of the following terms: "methylmercury compounds", "organomercury compounds", "neurologic manifestations", "memory disorders", "neurobehavioral manifestations" and "communication disorders" were performed in a systematic way. Studies focusing on MeHg exposure and subsequent neurological alteration on humans (>13 years) were included. Evaluation of methodological quality and risk of bias as well as the level of evidence was performed. Our results have identified 470 studies and six articles were eligible for systematic review inclusion criteria. The studies suggested alterations related to the psychosensory, motor and coordination system, as well as motor speech, hearing, visual impairment, mood alterations and loss of intelligent quotient. Of all the six studies, two presented a high risk of bias, with methodological problems related to the confounding factors and all studies presented evidence level ranged from very low to low. In this way our results revealed that a definitive demonstration of an association of MeHg and neurological alterations in human beings is still a pending subject. Future studies in this topic should take into consideration more confident and reliable methods to answer this question.
Topics: Animals; Environmental Exposure; Humans; Methylmercury Compounds; Motor Activity; Nervous System Diseases
PubMed: 30732869
DOI: 10.1016/j.jtemb.2018.12.001 -
Toxics Dec 2021Beside partial coverage in three reviews so far (1994, 2009, 2019), there is no review on genotoxic studies dealing with mercury (Hg) and human exposure using the most... (Review)
Review
Beside partial coverage in three reviews so far (1994, 2009, 2019), there is no review on genotoxic studies dealing with mercury (Hg) and human exposure using the most usual genotoxic assays: sister chromatid exchanges (SCE), chromosomal aberrations (CA), cytochalasin B blocked micronucleus assay (CBMN), and single-cell gel electrophoresis (SCGE or alkaline comet assay). Fifty years from the first Hg genotoxicity study and with the Minamata Convention in force, the genotoxic potential of Hg and its derivatives is still controversial. Considering these antecedents, we present this first systematic literature overview of genotoxic studies dealing with Hg and human exposure that used the standard genotoxic assays. To date, there is not sufficient evidence for Hg human carcinogen classification, so the new data collections can be of great help. A review was made of the studies available (those published before the end of October 2021 on PubMed or Web of Science in English or Spanish language) in the scientific literature dealing with genotoxic assays and human sample exposure ex vivo, in vivo, and in vitro. Results from a total of 66 articles selected are presented. Organic (o)Hg compounds were more toxic than inorganic and/or elemental ones, without ruling out that all represent a risk. The most studied inorganic (i)Hg compounds in populations exposed accidentally, occupationally, or iatrogenically, and/or in human cells, were Hg chloride and Hg nitrate and of the organic compounds, were methylmercury, thimerosal, methylmercury chloride, phenylmercuric acetate, and methylmercury hydroxide.
PubMed: 34941760
DOI: 10.3390/toxics9120326 -
Frontiers in Behavioral Neuroscience 2019Impulsive and compulsive traits represent a variety of maladaptive behaviors defined by the difficulties to stop an improper response and the control of a repeated...
Impulsive and compulsive traits represent a variety of maladaptive behaviors defined by the difficulties to stop an improper response and the control of a repeated behavioral pattern without sensitivity to changing contingencies, respectively. Otherwise, human beings are continuously exposed to plenty neurotoxicological agents which have been systematically linked to attentional, learning, and memory dysfunctions, both preclinical and clinical studies. Interestingly, the link between both impulsive and compulsive behaviors and the exposure to the most important xenobiotic compounds have been extensively developed; although the information has been rarely summarized. For this, the present systematic review schedule and analyze in depth the most important works relating different subtypes of the above-mentioned behaviors with 4 of the most important xenobiotic compounds: Lead (Pb), Methylmercury (MeHg), Polychlorinated biphenyls (PCB), and Organophosphates (OP) in both preclinical and clinical models. Systematic search strategy on PubMed databases was developed, and the most important information was structured both in text and in separate tables based on rigorous methodological quality assessment. For Lead, Methylmercury, Polychlorinated biphenyls and organophosphates, a total of 44 (31 preclinical), 34 (21), 38 (23), and 30 (17) studies were accepted for systematic synthesis, respectively. All the compounds showed an important empirical support on their role in the modulation of impulsive and, in lesser degree, compulsive traits, stronger and more solid in animal models with inconclusive results in humans in some cases (i.e., MeHg). However, preclinical and clinical studies have systematically focused on different subtypes of the above-mentioned behaviors, as well as impulsive choice or habit conformations have been rarely studied. The strong empirical support in preclinical studies contrasts with the lack of connection between preclinical and clinical models, as well as the different methodologies used. Further research should be focused on dissipate these differences as well as deeply study impulsive choice, decision making, risk taking, and cognitive flexibility, both in experimental animals and humans.
PubMed: 31333425
DOI: 10.3389/fnbeh.2019.00139 -
Environmental Research May 2016This paper describes country-specific estimates of the incidence of intellectual disability in children associated with prenatal exposure to methylmercury. A systematic... (Review)
Review
This paper describes country-specific estimates of the incidence of intellectual disability in children associated with prenatal exposure to methylmercury. A systematic review was undertaken to identify country-specific data on hair mercury concentrations in women of reproductive age. A variety of approaches were used to estimate biomarker concentrations for countries lacking such data. A dose-effect relationship derived on the basis of the data from three large prospective studies relating prenatal methylmercury exposure to IQ in children was used to estimate the country-specific incidences of mild, moderate, severe, and profound intellectual disability in children as a result of prenatal methylmercury exposure. The incidence of methylmercury-associated mild intellectual disability (IQ scores 50-70) varied nearly 40-fold across countries, with the greatest incidences generally in countries that are islands or that are coastal. Countries with high birth rates and greater consumption of foods that contribute most to methylmercury intake in humans (seafood, rice) can be expected to make the largest contributions to the worldwide burden of disease associated with methylmercury. The assumptions and limitations of the estimates are discussed.
Topics: Adolescent; Biomarkers; Child; Child, Preschool; Environmental Exposure; Female; Food Contamination; Humans; Incidence; Infant; Infant, Newborn; Intellectual Disability; Methylmercury Compounds; Pregnancy; Prenatal Exposure Delayed Effects; Risk Factors
PubMed: 26874048
DOI: 10.1016/j.envres.2015.10.006 -
Journal of Environmental Sciences... Oct 2019Mercury is an important pollutant, released into aquatic ecosystems both naturally and by anthropogenic action. This element is transferred to aquatic organisms in...
Mercury is an important pollutant, released into aquatic ecosystems both naturally and by anthropogenic action. This element is transferred to aquatic organisms in different ways, causing potential health risks. In addition, mercury can be accumulated by humans, especially through the consumption of contaminated food. This systematic review aims to present mercury pathways, the major routes through which this element reaches the aquatic environment and its transformations until becoming available to living animals, leading to bioaccumulation and biomagnification phenomena. The key biotic and abiotic factors affecting such processes, the impact of mercury on animal and human health and the issue of seafood consumption as a source of chronic mercury contamination are also addressed. A total of 101 articles were retrieved from a standardized search on three databases (PubMed, Emabse, and Web of Science), in addition to 28 other studies not found on these databases but considered fundamental to this review (totaling 129 articles). Both biotic and abiotic factors display fundamental importance in mediating mercurial dynamics, i.e., muscle tropism, and salinity, respectively. Consequently, mercurial contamination in aquatic environments affects animal health, especially the risk of extinction species and also on human health, with methylmercury the main mercury species responsible for acute and chronic symptomatology.
Topics: Animals; Aquatic Organisms; Environmental Pollutants; Humans; Mercury; Methylmercury Compounds; Risk Assessment; Seafood
PubMed: 31284912
DOI: 10.1016/j.jes.2019.02.018 -
Environmental Research Mar 2019We describe analyses to estimate the global burden of disease associated with methylmercury (MeHg). An intelligence quotient < 70, indicating intellectual disability...
We describe analyses to estimate the global burden of disease associated with methylmercury (MeHg). An intelligence quotient < 70, indicating intellectual disability (ID), was selected as the critical disease, maternal hair Hg concentration during pregnancy selected as the critical exposure biomarker, and a dose-effect relationship of an 0.18 point IQ reduction per µg/g increase in maternal hair Hg was assumed, based on a meta-analysis. A systematic review was conducted to obtain country-specific data on the distribution of maternal hair Hg concentrations. The country-specific incidence of MeHg-associated ID was calculated, and a random effects model was used to impute the incidence for countries for which no exposure data could be found. The global burden of MeHg-associated ID was quantified in terms of Disability-Adjusted Life Years (DALYs) using the World Health Organization (WHO) Global Health Estimates methodology, and presented by 14 subregions. In 2015, the global total for MeHg-associated cases of ID was 226,655; 210,074 of these cases (93%) were mild cases of ID. The highest rate of ID (6 cases per 100,000 population) was found in the Americas D subregion. The global DALY estimate was 1,963,869. The Western Pacific B subregion contributed the most to this total (696,417), although the Americas D subregion had the greatest rate (54 DALYs per 100,000 population). The burden of disease associated with MeHg is therefore highly subregion-dependent even in areas that are geographically related. The priority given to reducing this burden can therefore be expected to vary considerably by subregion depending on other health needs.
Topics: Female; Humans; Pregnancy; Disabled Persons; Environmental Exposure; Global Health; Intellectual Disability; Methylmercury Compounds; Prenatal Exposure Delayed Effects; Quality-Adjusted Life Years
PubMed: 30623889
DOI: 10.1016/j.envres.2018.12.042