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Current Environmental Health Reports Sep 2015Mercury affects the nervous system and has been implicated in altering heart rhythm and function. We sought to better define its role in modulating heart rate... (Review)
Review
BACKGROUND
Mercury affects the nervous system and has been implicated in altering heart rhythm and function. We sought to better define its role in modulating heart rate variability, a well-known marker of cardiac autonomic function.
DESIGN
This is a systematic review study.
METHODS
We searched PubMed, Embase, TOXLINE, and DART databases without language restriction. We report findings as a qualitative systematic review because heterogeneity in study design and assessment of exposures and outcomes across studies, as well as other methodological limitations of the literature, precluded a quantitative meta-analysis.
RESULTS
We identified 12 studies of mercury exposure and heart rate variability in human populations (ten studies involving primarily environmental methylmercury exposure and two studies involving occupational exposure to inorganic mercury) conducted in Japan, the Faroe Islands, Canada, Korea, French Polynesia, Finland, and Egypt. The association of prenatal mercury exposure with lower high-frequency band scores (thought to reflect parasympathetic activity) in several studies, in particular the inverse association of cord blood mercury levels with the coefficient of variation of the R-R intervals and with low-frequency and high-frequency bands at 14 years of age in the Faroe Islands birth cohort study, suggests that early mercury exposure could have a long-lasting effect on cardiac parasympathetic activity. Studies with later environmental exposures to mercury in children or in adults were heterogeneous and did not show consistent associations.
CONCLUSIONS
The evidence was too limited to draw firm causal inferences. Additional research is needed to elucidate the effects of mercury on cardiac autonomic function, particularly as early-life exposures might have lasting impacts on cardiac parasympathetic function.
Topics: Adolescent; Adult; Autonomic Nervous System; Child; Environmental Exposure; Female; Heart; Heart Rate; Humans; Male; Mercury; Mercury Poisoning, Nervous System; Occupational Exposure; Pregnancy; Prenatal Exposure Delayed Effects
PubMed: 26231507
DOI: 10.1007/s40572-015-0053-0 -
Environmental Research Feb 2021There is evidence that exposure to mercury (Hg) may be a risk factor for cardiovascular disease (CVD). (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
There is evidence that exposure to mercury (Hg) may be a risk factor for cardiovascular disease (CVD).
OBJECTIVE
To conduct a systematic review of published studies and a meta-analysis of the results to examine the associations between chronic Hg exposure and CVD outcomes.
METHODS
We searched PubMed, Embase, and TOXLINE using previously developed strategies. Studies were selected according to a priori-defined inclusion criteria, and their qualities were assessed. Study estimates were extracted, and subgroup analyses were conducted to explore potential sources of heterogeneity: 1) fatal vs. nonfatal events, 2) cohort study vs. non-cohort study, and 3) inorganic Hg vs. methyl mercury (MeHg). Dose-response meta-analyses were conducted for MeHg exposure and fatal/nonfatal ischemic heart disease (IHD), stroke, and all CVD.
RESULTS
A total of 14 studies reporting results collected from more than 34,000 participants in 17 countries were included in the meta-analysis. Hg exposure was associated with an increase in nonfatal IHD (relative risk (RR): 1.21 (0.98, 1.50)), all-cause mortality (RR: 1.21 (0.90, 1.62)), CVD mortality (RR: 1.68 (1.15, 2.45)), and mortality due to other heart diseases (RR: 1.50 (1.07, 2.11)). No association was observed between Hg exposure and stroke. A heterogeneous relationship was found between studies reporting fatal and nonfatal outcomes and between cohort and non-cohort studies. However, these differences were mainly due to differences in Hg exposure level. Occupational inorganic Hg exposure was associated with similar increases in different mortality outcomes. A J-shaped relationship between Hg exposure and different fatal/nonfatal outcomes was observed, with turning points at hair Hg concentrations of 1 μg/g for IHD and 2 μg/g for stroke and all CVD.
CONCLUSION
Chronic exposure to Hg was associated with an increased risk of all-cause mortality and fatal/nonfatal IHD. The risk of multiple cardiovascular endpoints starts to increase consistently at a hair Hg concentration of 2 μg/g.
Topics: Cardiovascular Diseases; Cohort Studies; Humans; Mercury; Risk Factors; Stroke
PubMed: 33285155
DOI: 10.1016/j.envres.2020.110538 -
The Science of the Total Environment Aug 2018Artisanal gold mining (AGM) continues to be a pervasive global health issue. While there are various problems associated with AGM, mercury exposure is the primary hazard... (Review)
Review
Artisanal gold mining (AGM) continues to be a pervasive global health issue. While there are various problems associated with AGM, mercury exposure is the primary hazard contributing to adverse health effects in exposed human populations. Over the last several decades, many interventions have been developed and implemented to curb mercury emissions and releases, notwithstanding a comprehensive review of context specific effectiveness. A systematic review was conducted in order to specifically assess the impact of current mercury interventions within the AGM sector worldwide. To aid in this review, a resource pool of information on AGM and mercury, treatment and management of emissions and releases, and interventions was assembled through a search conducted via multiple search engines. This search determined that there have been many strategies used to reduce or eliminate mercury, through interventions or programs focusing on education, processing centers, or mercury alternative techniques. Education has focused on environment or health awareness or more specifically on cleaner or alternative techniques. Processing centers offered artisanal miners rudimentary equipment for grinding and amalgamation that extract less than 30% of the gold as an exchange for their tailings. Some techniques reduced mercury releases including retorts, mill leaching, vat-leaching, and others replaced mercury from the process such as magnets, direct smelting, sluices, and borax. There are both positive and negative outcomes associated with every intervention. Novel and comprehensive strategies-including mercury removal technology, miner education on mercury hazards, economic gains, and policy-are needed to address mercury public health issues associated with AGM.
PubMed: 29602119
DOI: 10.1016/j.scitotenv.2018.03.241 -
International Journal of Environmental... Feb 2022Neurodevelopmental delays can interfere with children's engagement with the world and further development, and may have negative consequences into adulthood. Mercury is... (Review)
Review
Neurodevelopmental delays can interfere with children's engagement with the world and further development, and may have negative consequences into adulthood. Mercury is highly toxic and may negatively influence neurodevelopment because it can freely cross the placenta and accumulate in the fetal brain. We searched four publication databases (Embase, PsycINFO, PubMed/MEDLINE, Scopus) for studies examining the relationship between early life mercury exposure and scores on neurodevelopmental performance measures in children aged 0 to 5 years old. Study quality was assessed using the National Institutes of Health (NIH) Quality Assessment Tool. Thirty-two prospective studies were included in the review. Neurodevelopmental performance was measured using 23 different scales, most commonly the Bayley Scales of Infant and Toddler Development (BSID). In most cases, the evidence for an association between mercury and neurodevelopment was weak. There did not appear to be exceptions for particular childhood ages, outcome scales, or mercury levels. The small number of results to the contrary were more likely to be studies which did not meet our high-quality criteria, and could be a consequence of multiple testing, selection bias, or incomplete confounder adjustment. Based on current evidence, dietary mercury exposure during pregnancy is unlikely to be a risk factor for low neurodevelopmental functioning in early childhood.
Topics: Adult; Child Development; Child, Preschool; Female; Humans; Infant; Infant, Newborn; Mercury; Placenta; Pregnancy; Prenatal Exposure Delayed Effects; Prospective Studies; Vitamins
PubMed: 35206164
DOI: 10.3390/ijerph19041976 -
Revista Brasileira de Ginecologia E... Dec 2022The present review aimed to synthesize the evidence regarding mercury (Hg) exposure and hypertensive disorders of pregnancy (HDP).
OBJECTIVE
The present review aimed to synthesize the evidence regarding mercury (Hg) exposure and hypertensive disorders of pregnancy (HDP).
DATA SOURCES
The PubMed, BVS/LILACS, SciELO and UFRJ's Pantheon Digital Library databases were systematically searched through June 2021.
STUDY SELECTION
Observational analytical articles, written in English, Spanish, or Portuguese, without time restriction.
DATA COLLECTION
We followed the PICOS strategy, and the methodological quality was assessed using the Downs and Black checklist.
DATA SYNTHESIS
We retrieved 77 articles, of which 6 met the review criteria. They comprised 4,848 participants, of which 809 (16.7%) had HDP and 4,724 (97.4%) were environmentally exposed to Hg (fish consumption and dental amalgam). Mercury biomarkers evaluated were blood (four studies) and urine (two studies). Two studies found a positive association between Hg and HDP in the group with more exposure, and the other four did not present it. The quality assessment revealed three satisfactory and three good-rated studies (mean: 19.3 ± 1.6 out 28 points). The absence or no proper adjustment for negative confounding factor, such as fish consumption, was observed in five studies.
CONCLUSION
We retrieved only six studies, although Hg is a widespread toxic metal and pregnancy is a period of heightened susceptibility to environmental threats and cardiovascular risk. Overall, our review showed mixed results, with two studies reporting a positive association in the group with more exposure. However, due to the importance of the subject, additional studies are needed to elucidate the effects of Hg on HDP, with particular attention to adjusting negative confounding.
Topics: Humans; Pregnancy; Female; Animals; Mercury; Hypertension, Pregnancy-Induced; Maternal Exposure; Biomarkers
PubMed: 36580940
DOI: 10.1055/s-0042-1760215 -
Critical Reviews in Toxicology Nov 2017The neurotoxicity of elemental mercury (Hg) is well-recognized, but it is uncertain whether and for how long neurotoxicity persists; among studies that evaluated... (Review)
Review
The neurotoxicity of elemental mercury (Hg) is well-recognized, but it is uncertain whether and for how long neurotoxicity persists; among studies that evaluated previously exposed workers, only one examined workers during and also years after exposure ceased. The aim of this review is to document the type, frequency, and dose-relatedness of objective neurological effects in currently exposed mercury workers and thereby provide first approximations of the effects one would have expected in previously exposed workers evaluated during exposure. We systematically reviewed studies of neurotoxicity in currently exposed mercury workers identified by searching MEDLINE (1950-2015), government reports, textbook chapters, and references cited therein; dental cohorts were not included. Outcomes on physical examination (PE), neurobehavioral (NB) tests, and electrophysiological studies were extracted and evaluated for consistency and dose-relatedness. Forty-five eligible studies were identified, comprising over 3000 workers chronically exposed to a range of Hg concentrations (0.002-1.7 mg/m). Effects that demonstrated consistency across studies and increased frequency across urine mercury levels (<50; 50-99; 100-199; ≥200 μg/L) included tremor, impaired coordination, and abnormal reflexes on PE, and reduced performance on NB tests of tremor, manual dexterity and motor speed. The data suggest response thresholds of U ≈275 μg/L for PE findings and ≈20 μg/L for NB outcomes. These results indicate that PE is of particular value for assessing workers with U >200 μg/L, while NB testing is more appropriate for those with lower U levels. They also provide benchmarks to which findings in workers with historical exposure can be compared.
Topics: Adult; Air Pollutants, Occupational; Humans; Male; Mercury; Middle Aged; Neurotoxicity Syndromes; Occupational Diseases; Occupational Exposure
PubMed: 28718354
DOI: 10.1080/10408444.2017.1342598 -
Clinical Rheumatology Dec 2022The relationship between exposure to certain metals and the risk of hyperuricemia (HUA) has biological plausibility, yet prior studies have presented inconsistent... (Meta-Analysis)
Meta-Analysis Review
The relationship between exposure to certain metals and the risk of hyperuricemia (HUA) has biological plausibility, yet prior studies have presented inconsistent findings. We aim to clarify the relationship between exposure to certain metals and HUA using a systematic review and meta-analysis approach. We searched the Web of Science, Embase, MEDLINE, Pubmed, Corchrane and China National Knowledge Infrastructure databases from inception through December, 2021 in order to identify studies that assessed the relationships between metals and the risk of HUA. Data were pooled by random-effects models and expressed as pooled odds ratios (OR) and 95% confidence intervals (CIs). The risk of bias was assessed using a tool from Agency for Healthcare Research and Quality (AHRQ). Twenty eligible articles (nineteen cross-sectional studies and one cohort) were included in our analysis, involving 63,283 participants in total. The studies showed that arsenic (pooled OR = 1.702, 95% CI: 1.44, 2.011; n = 6, I = 29.5%), calcium (pooled OR = 1.765, 1.111, 2.804; 4, 82.3%), cadmium (pooled OR = 1.199,1.020, 1.410; 11, 38.5%) and lead (pooled OR = 1.564,1.205, 2.030; 11, 72.9%) exposure were, all linked to an increased risk of HUA. Exposure to molybdenum (pooled OR = 0.804, 0.724, 0.975, 3, 0%) was linked to a decreased risk of HUA, however. Exposure to arsenic, calcium, cadmium and lead is associated with an increased risk of HUA. Molybdenum exposure was associated with a decreased prevalence of HUA; however, aluminum, cobalt, copper, iron, magnesium, manganese, mercury, selenium, thallium and zinc are not associated with HUA risk. Further experimental studies are warranted to decipher the mechanisms by which exposure to the above metals affect HUA risk. The findings reinforced the importance of metals in the HUA risk, and provided a reference for legislation to prevent HUA and protect people's health.
Topics: United States; Humans; Cadmium; Arsenic; Molybdenum; Calcium; Hyperuricemia; Cross-Sectional Studies
PubMed: 36109472
DOI: 10.1007/s10067-022-06362-1 -
International Journal of Environmental... Sep 2022Electronic waste (e-waste) recycling releases mercury (Hg) into the environment, though to our knowledge Hg levels at such sites have yet to be examined on a worldwide... (Meta-Analysis)
Meta-Analysis Review
Electronic waste (e-waste) recycling releases mercury (Hg) into the environment, though to our knowledge Hg levels at such sites have yet to be examined on a worldwide basis. A systematic review of scientific studies was conducted to extract, analyze, and synthesize data on Hg levels in e-waste products, environments near recycling sites, and in people. Data were extracted from 78 studies from 20 countries, and these included Hg levels in 1103 electrical and electronic products, 2072 environmental samples (soil, air, plant, food, water, dust), and 2330 human biomarkers (blood, hair, urine). The average Hg level in products was 0.65 μg/g, with the highest levels found in lamps (578 μg/g). Average soil and sediment Hg levels (1.86 μg/g) at e-waste sites were at least eight times higher than at control sites. Average urinary Hg levels (0.93 μg/g creatinine) were approximately two-fold higher among e-waste workers versus control groups. Collectively, these findings demonstrate that e-waste recycling may lead to Hg contamination in environments and human populations in close proximity to processing sites. These findings contribute to a growing knowledge base of mercury exposure through diverse source-exposure pathways, and the work has potential policy implications in the context of the Minamata Convention.
Topics: Biomarkers; Creatinine; Dust; Electronic Waste; Environmental Monitoring; Humans; Mercury; Soil; Waste Products; Water Pollutants, Chemical
PubMed: 36231146
DOI: 10.3390/ijerph191911843 -
International Journal of Clinical... 2022Scopus and PubMed databases were systematically searched from their inception to November 2021 to obtain pertinent studies. Standardized mean differences (SMDs) with... (Meta-Analysis)
Meta-Analysis Review
METHODS
Scopus and PubMed databases were systematically searched from their inception to November 2021 to obtain pertinent studies. Standardized mean differences (SMDs) with corresponding 95% confidence intervals (CIs) were calculated to evaluate the difference in Hg levels between people with and without T2DM. The association of the Hg exposure with T2DM was assessed using a random-effects model by pooling the odds ratios (ORs) and 95% CIs.
RESULTS
A total of 17 studies, with 42,917 participants, aged ≥18 years, were analyzed. Overall, Hg levels were significantly higher in T2DM patients compared with non-T2DM controls (SMD = 1.07; 95%CI = 0.59 to 1.55, ≤ 0.001), with significant heterogeneity across studies (I = 96.1%; =≤0.001). No significant association was found between Hg exposure and risk of T2DM in the overall analysis and subgroup analysis based on the source of sample and study design. However, higher exposure to Hg was related to reduced risk of T2DM in men (OR = 0.71; 95%CI = 0.57 to 0.88), but not in women. No significant evidence for publication bias was detected.
CONCLUSIONS
Although the Hg level in T2DM is significantly higher than that of nondiabetics, there was no association between Hg exposure and the overall risk of T2DM. Nevertheless, our study shows that higher exposure to Hg might reduce the risk of T2DM in men.
Topics: Adolescent; Adult; Diabetes Mellitus, Type 2; Female; Humans; Male; Mercury; Odds Ratio
PubMed: 36101810
DOI: 10.1155/2022/7640227 -
Reproductive Toxicology (Elmsford, N.Y.) Apr 2019Evidences from human and animal studies suggest that reproductive function may be affected by mercury. The aim of this review was to explore the mercury influence on...
BACKGROUND
Evidences from human and animal studies suggest that reproductive function may be affected by mercury. The aim of this review was to explore the mercury influence on human fertility.
METHODS
A systematic search was made in PubMED for papers published between 1975-2017, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.
RESULTS
Increased mercury levels were associated with infertility or subfertility status. Further, infertile subjects with unexplained infertility showed higher levels of mercury in hair, blood and urine than fertile ones. Mercury exposure induced sperm DNA damage and abnormal sperm morphology and motility. Additionally, mercury levels were related with higher incidence of menstrual and hormonal disorders and increased rates of adverse reproductive outcomes.
CONCLUSIONS
Our review showed that mercury negatively impacts human reproduction, affecting the reproductive and endocrine systems in both male and female. However, the molecular mechanisms underlying the mercury-associated decline on fertility remains unknown.
Topics: Environmental Pollutants; Female; Fertility; Humans; Male; Mercury; Ovarian Follicle; Reproduction; Reproductive Health; Spermatozoa
PubMed: 30831212
DOI: 10.1016/j.reprotox.2019.02.012