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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 -
Archivos Argentinos de Pediatria Oct 2023Mercury is a toxic metal which can cross the placenta and the blood-brain barrier and cause the disruption of various cellular processes. Studies have investigated...
Mercury is a toxic metal which can cross the placenta and the blood-brain barrier and cause the disruption of various cellular processes. Studies have investigated mercury exposure and neurodevelopmental disorders; therefore, a critical and rigorous analysis of this evidence is required. The objective of this review was to evaluate the available scientific evidence on the effects of mercury exposure during the prenatal and postnatal periods and its relationship with the development of neurobehavioral disorders. A systematic search of the MEDLINE and ScienceDirect databases was conducted; the results were presented in tables and narrative synthesis. Only 31 studies met the eligibility criteria. Overall, the evidence on the effects of mercury exposure and neurodevelopmental disorders in children is limited. Learning disabilities, autism, and attention deficit hyperactivity disorder were some of the reported potential effects.
Topics: Pregnancy; Female; Child; Humans; Mercury; Neurodevelopmental Disorders; Attention Deficit Disorder with Hyperactivity; Autistic Disorder
PubMed: 37145892
DOI: 10.5546/aap.2022-02838.eng -
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 -
Environmental Research Jun 2021Toenails have been used as biomarkers of exposure to toxic metals, but their validity for this purpose is not yet clear and might differ depending on the specific agent.... (Review)
Review
Toenails have been used as biomarkers of exposure to toxic metals, but their validity for this purpose is not yet clear and might differ depending on the specific agent. To evaluate this issue, we reviewed the literature on: a) the time-window of exposure reflected by toenails; b) the reproducibility of toenail toxic-metal levels in repeated measures over time; c) their relationship with other biomarkers of exposure, and; d) their association with potential determinants (i.e. sociodemographic, anthropometric, or lifestyle characteristics) or with sources of exposure like diet or environmental pollution. Thus, we performed a systematic review, searching for articles that provided original data for levels of any of the following toxic metals in toenails: aluminum, beryllium, cadmium, chromium, mercury, nickel, lead, thallium and uranium. We identified 88 articles, reporting data from 67 different research projects, which were quite heterogeneous with regard to population profile, sample size and analytical technique. The most commonly studied metal was mercury. Concerning the time-window of exposure explored by toenails, some reports indicate that toenail cadmium, nickel and lead may reflect exposures that occurred 7-12 months before sampling. For repeated samples obtained 1-6 years apart, the range of intraindividual correlation coefficients of aluminum, chromium and mercury was 0.33-0.56. The correlation of toxic metal concentrations between toenails and other matrices was higher for hair and fingernails than for urine or blood. Mercury levels were consistently associated with fish intake, while other toxic metals were occasionally associated with specific sources (e.g. drinking water, place of residence, environmental pollution, and occupation). The most frequently evaluated health endpoints were cardiovascular diseases, cancer, and central nervous system diseases. Available data suggest that toenail mercury levels reflected long-term exposures and showed positive associations with fish intake. The lack of standardization in sample collection, quality control, analytical techniques and procedures - along with the heterogeneity and conflicting results among studies - mean it is still difficult to conclude that toenails are a good biomarker of exposure to toxic metals. Further studies are needed to draw solid conclusions about the suitability of toenails as biomarkers of exposure to toxic metals.
Topics: Animals; Biomarkers; Environmental Exposure; Mercury; Metals; Nails; Reproducibility of Results
PubMed: 33753073
DOI: 10.1016/j.envres.2021.111028 -
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 -
Pharmaceutical Biology Aug 2016Spirulina (Arthrospira) exerts a wide spectrum of pharmacological activities which are mainly attributed to its antioxidant effect. However, Spirulina has also been... (Review)
Review
CONTEXT
Spirulina (Arthrospira) exerts a wide spectrum of pharmacological activities which are mainly attributed to its antioxidant effect. However, Spirulina has also been reported (both in preclinical and in clinical scenarios) to exhibit other bioactive effects, including an antitoxic potential.
OBJECTIVE
We performed a systematic review of the literature, conducted in TOXNET, PubMed/MEDLINE, and Science Direct-Scopus; all available years were included. Searching criteria included the effects of Spirulina on experimental poisonings from arsenic, cadmium, carbon tetrachloride, deltamethrin, fluoride, hexachlorocyclohexane, iron, lead, lindane, and mercury.
RESULTS
In all cases, it was established that the blue-green alga, and its isolated compounds, effectively counteracted these pollutants toxic effects on the exposed organisms. Some molecular mechanisms are proposed, although they have not been fully elucidated yet.
CONCLUSION
Spirulina could be a useful coadjuvant agent within clinical practice for treatment of these or other pollutants poisonings.
Topics: Animals; Antidotes; Antioxidants; Environmental Exposure; Environmental Pollutants; Humans; Occupational Exposure; Poisoning; Spirulina
PubMed: 26439611
DOI: 10.3109/13880209.2015.1077464 -
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 -
Prevention Science : the Official... May 2024Exposure to certain chemicals prenatally and in childhood can impact development and may increase risk for attention-deficit/hyperactivity disorder (ADHD). Leveraging a... (Meta-Analysis)
Meta-Analysis Review
Exposure to certain chemicals prenatally and in childhood can impact development and may increase risk for attention-deficit/hyperactivity disorder (ADHD). Leveraging a larger set of literature searches conducted to synthesize results from longitudinal studies of potentially modifiable risk factors for childhood ADHD, we present meta-analytic results from 66 studies that examined the associations between early chemical exposures and later ADHD diagnosis or symptoms. Studies were eligible for inclusion if the chemical exposure occurred at least 6 months prior to measurement of ADHD diagnosis or symptomatology. Included papers were published between 1975 and 2019 on exposure to anesthetics (n = 5), cadmium (n = 3), hexachlorobenzene (n = 4), lead (n = 22), mercury (n = 12), organophosphates (n = 7), and polychlorinated biphenyls (n = 13). Analyses are presented for each chemical exposure by type of ADHD outcome reported (categorical vs. continuous), type of ADHD measurement (overall measures of ADHD, ADHD symptoms only, ADHD diagnosis only, inattention only, hyperactivity/impulsivity only), and timing of exposure (prenatal vs. childhood vs. cumulative), whenever at least 3 relevant effect sizes were available. Childhood lead exposure was positively associated with ADHD diagnosis and symptoms in all analyses except for the prenatal analyses (odds ratios (ORs) ranging from 1.60 to 2.62, correlation coefficients (CCs) ranging from 0.14 to 0.16). Other statistically significant associations were limited to organophosphates (CC = 0.11, 95% confidence interval (CI): 0.03-0.19 for continuous measures of ADHD outcomes overall), polychlorinated biphenyls (CC = 0.08, 95% CI: 0.02-0.14 for continuous measures of inattention as the outcome), and both prenatal and childhood mercury exposure (CC = 0.02, 95% CI: 0.00-0.04 for continuous measures of ADHD outcomes overall for either exposure window). Our findings provide further support for negative impacts of prenatal and/or childhood exposure to certain chemicals and raise the possibility that primary prevention and targeted screening could prevent or mitigate ADHD symptomatology. Furthermore, these findings support the need for regular review of regulations as our scientific understanding of the risks posed by these chemicals evolves.
Topics: Attention Deficit Disorder with Hyperactivity; Humans; Child; Environmental Exposure; Female; Prenatal Exposure Delayed Effects; Pregnancy
PubMed: 38108946
DOI: 10.1007/s11121-023-01601-6 -
The Science of the Total Environment Apr 2022The etiology of sporadic amyotrophic lateral sclerosis (ALS) is still unclear. We evaluate environmental factors suspected to be associated with ALS for their potential... (Review)
Review
The etiology of sporadic amyotrophic lateral sclerosis (ALS) is still unclear. We evaluate environmental factors suspected to be associated with ALS for their potential linkage to disease causality and to model geographic distributions of susceptible populations and expected cases worldwide. A PRISMA systematic literature review was performed 2021. Bradford Hill criteria were used to identify and rank environmental factors and a secondary review of ALS diagnoses in population studies and ALS case or cohort studies was conducted. Prevalence rate projection informed estimates of impacted regions and populations. Among 1710 papers identified, 258 met the inclusion criteria, of which 173 responded to at least one of nine Bradford Hill criteria among 83 literature-identified ALS environmental factors. Environmental determinants of ALS in order of decreasing significance were β-N-methylamino-L-alanine (BMAA), formaldehyde, selenium, and heavy metals including manganese, mercury, zinc, and copper. Murine animal models were the most common methodology for exploring environmental factors. Another line of investigation of 62 population exposure studies implicated the same group of environmental agents (mean odds ratios): BMAA (2.32), formaldehyde (1.54), heavy metals (2.99), manganese (3.85), mercury (2.74), and zinc (2.78). An age-adjusted incidence model estimated current total ALS cases globally at ~85,000 people compared to only ~1600 cases projected from the reported ALS incidence in the literature. Modeling with the prevalence microscope equation forecasted an increase in U.S. ALS cases from 16,707 confirmed in 2015 to ~22,650 projected for 2040. Two orthogonal methods employed implicate BMAA, formaldehyde, manganese, mercury, and zinc as environmental factors with strong ALS associations. ALS cases likely are significantly underreported globally, and high vulnerability exists in regions with large aging populations. Recent studies on other diseases with environmental determinants suggest the need to consider additional potential triggers and mechanisms, including exposures to microbial agents and epigenetic modifications.
Topics: Amyotrophic Lateral Sclerosis; Animals; Formaldehyde; Humans; Mercury; Mice; Selenium; Zinc
PubMed: 34971691
DOI: 10.1016/j.scitotenv.2021.152504