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Laryngoscope Investigative... Apr 2024Previous studies have shown an association between environmental exposure to heavy metals and hearing loss. However, the findings regarding the relationship between... (Review)
Review
BACKGROUND AND OBJECTIVES
Previous studies have shown an association between environmental exposure to heavy metals and hearing loss. However, the findings regarding the relationship between exposure to different metals and hearing loss development are inconsistent. To address this, we conducted a meta-analysis to explore the link between common heavy metal exposures and hearing loss. This study examined the effects of lead (Pb), cadmium (Cd), and mercury (Hg) pollution on hearing loss at various levels, and systematically reviewed the literature on manganese (Mn), barium (Ba), arsenic (As), and hearing loss.
METHODS
We conducted systematic searches in five major databases, including PubMed, Web of Science, Embase, Cochrane Library, and Scopus. In addition, we searched three Chinese digital libraries: CNKI, Wanfang Data, and Wipu. From an initial pool of 649 articles, we carefully screened and selected 15 articles for further analysis. The effect sizes from these selected studies were synthesized through a meta-analysis to calculate the overall effect size.
RESULTS
Our findings showed that: (1) There was a significant association between Pb and Cd exposure and hearing loss; (2) There is a proportional relationship between the increase of metal index detected in blood and hearing loss; (3) In the PTA measurement of hearing loss at different frequencies, the 4 kHz high frequency range had a stronger correlation with hearing loss than the low frequency, with OR 1.44 (1.22, 1.71); and (4) There was a more significant correlation between Barium (Ba) levels in nails and hair than in urine.
CONCLUSIONS
The study presented evidence of a significant association between human hearing loss and exposure to lead (Pb) and cadmium (Cd). It not only revealed a positive correlation between blood heavy metal concentrations and the incidence of hearing loss but also highlighted that long-term exposure indicators of heavy metals were more indicative of the correlation with hearing loss. Lastly, the study recommends utilizing high frequency 4 kHz for the effective assessment and diagnosis of hearing loss caused by exposure to heavy metals.
PubMed: 38562156
DOI: 10.1002/lio2.1230 -
Journal of Gynecology Obstetrics and... Jun 2024Infertility has been defined as a failure to conceive for at least 12 months of regular unprotected sexual intercourse. The male factors are responsible for about 50 %... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Infertility has been defined as a failure to conceive for at least 12 months of regular unprotected sexual intercourse. The male factors are responsible for about 50 % of cases. Various factors such as endocrine, immunological, genetic, exposure to toxicants, and idiopathic factors are involved in male infertility. Recently, the role of PTEs in reproductive performance has been explored by various studies.
OBJECTIVES
Current systematic review and meta-analysis have been carried out to compile and statistically analyze the findings of relevant studies and reach some conclusion.
METHODOLOGY
A literature search was done according to the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines in three scientific literature databases; PubMed, Google Scholar, and Science Direct. Meta-analysis was performed using Review Manager 5.4 software. The study's protocol was registered in PROSPERO (CRD42023465776).
RESULTS
Meta-analysis of lead in the blood of infertile cases and healthy controls indicated a significant association with male infertility, observed standard mean difference (SMD) was 0.67 at 95 % confidence interval (CI) (0.07, 1.28), and p = 0.03. In the case of lead analysis in semen, the values are as follows: SMD = 1.19 at 95 % CI (0.42, 1.96) with p = 0.002. Significant association appears for cadmium in semen with SMD 0.92 at 95 % CI (0.54, 1.29) and p < 0.00001. No significant association was observed for arsenic, barium, and mercury in blood.
CONCLUSION
Most of the studies focus on the detection of PTE in semen samples followed by blood as sample type. Lead and cadmium exposure is significantly associated with male infertility. However, non-significant results for arsenic, barium, and mercury are observed.
Topics: Humans; Male; Infertility, Male; Cadmium; Lead; Mercury; Semen; Arsenic; Environmental Exposure
PubMed: 38554943
DOI: 10.1016/j.jogoh.2024.102782 -
Heliyon Mar 2024The present study was conducted to investigate the differences in cadmium (Cd) and mercury (Hg) concentrations between children with autism spectrum disorder (ASD) and...
The present study was conducted to investigate the differences in cadmium (Cd) and mercury (Hg) concentrations between children with autism spectrum disorder (ASD) and controls. In this systematic review and meta-analysis study, three thousand one hundred forty-five studies were collected from scientific databases including Web of Science, Scopus, PubMed, and Google Scholar from January 2000 to October 2022 and were investigated for eligibility. As a result, 37 studies published in the period from 2003 to 2022 met our inclusion criteria and were considered in the meta-analysis. The heterogeneity assumption was evaluated using the Chi-squared-based Q-test and I-squared (I) statistics. The pooled estimates were shown in the forest plots with Hedges' g (95% confidence interval) values. The random effects model demonstrated that there is no significant difference in the blood (Hedges' g: 0.14, 95% CI: 0.45, 0.72, > 0.05), hair (Hedges' g: 0.12, 95% CI: 0.26, 0.50, > 0.05), and urinary (Hedges' g: 0.05, 95% CI: 0.86, 0.76, > 0.05) Cd levels of the case group versus control subjects. Moreover, the pooled findings of studies showed no significant difference in the blood (Hedges' g: 1.69, 95% CI: 0.09, 3.48, > 0.05), hair (Hedges' g: 3.42, 95% CI: 1.96, 8.80, > 0.05), and urinary (Hedges' g: 0.49, 95% CI: 1.29 - 0.30, > 0.05) Hg concentrations. The results demonstrated no significant differences in Hg and Cd concentrations in different biological samples of children with ASD compared to control subjects.
PubMed: 38496888
DOI: 10.1016/j.heliyon.2024.e27789 -
Environmental Pollution (Barking, Essex... May 2024The gut-brain axis is a crucial interface between the central nervous system and the gut microbiota. Recent evidence shows that exposure to environmental contaminants,... (Review)
Review
The gut-brain axis is a crucial interface between the central nervous system and the gut microbiota. Recent evidence shows that exposure to environmental contaminants, such as heavy metals, can cause dysbiosis in gut microbiota, which may affect the gut-brain communication, impacting aspects of brain function and behavior. This systematic review of the literature aims to evaluate whether deleterious effects on brain function due to heavy metal exposure could be mediated by changes in the gut microbiota profile. Animal studies involving exposure to heavy metals and a comparison with a control group that evaluated neuropsychological outcomes and/or molecular outcomes along with the analysis of microbiota composition were reviewed. The authors independently assessed studies for inclusion, extracted data and assessed risk of bias using the protocol of Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) for preclinical studies. A search in 3 databases yielded 16 eligible studies focused on lead (n = 10), cadmium (n = 1), mercury (n = 3), manganese (n = 1), and combined exposure of lead and manganese (n = 1). The animal species were rats (n = 7), mice (n = 4), zebrafish (n = 3), carp (n = 1) and fruit fly (n = 1). Heavy metals were found to adversely affect cognitive function, behavior, and neuronal morphology. Moreover, heavy metal exposure was associated with changes in the abundance of specific bacterial phyla, such as Firmicutes and Proteobacteria, which play crucial roles in gut health. In some studies, these alterations were correlated with learning and memory impairments and mood disorders. The interplay of heavy metals, gut microbiota, and brain suggests that heavy metals can induce direct brain alterations and indirect effects through the microbiota, contributing to neurotoxicity and the development of neuropsychological disorders. However, the small number of papers under review makes it difficult to draw definitive conclusions. Further research is warranted to unravel the underlying mechanisms and evaluate the translational implications for human health.
Topics: Mice; Rats; Animals; Humans; Gastrointestinal Microbiome; Manganese; Zebrafish; Metals, Heavy; Brain
PubMed: 38462196
DOI: 10.1016/j.envpol.2024.123732 -
Environmental Science and Pollution... Mar 2024Coal-fired power plants (CFPPs) are one of the most significant sources of mercury (Hg) emissions certified by the Minamata Convention, which has attracted much... (Review)
Review
Coal-fired power plants (CFPPs) are one of the most significant sources of mercury (Hg) emissions certified by the Minamata Convention, which has attracted much attention in recent years. In this study, we used the Web of Science and CiteSpace to analyze the knowledge structure of this field from 2000 to 2022 and then reviewed it systematically. The field of Hg emissions from coal-fired power plants has developed steadily. The research hotspots can be divided into three categories: (1) emission characterization research focused on speciation changes and emission calculations; (2) emission control research focused on control technologies; (3) environmental impact research focused on environmental pollution and health risk. In conclusion, using an oxygen-rich atmosphere for combustion and installing high-efficiency air pollution control devices (APCDs) helped to reduce the formation of Hg. The average Hg removal rates of APCDs and modified adsorbents after ultra-low emission retrofit were distributed in the range of 82-93% and 41-100%, respectively. The risk level of Hg in combustion by-products was highest in desulfurization sludge (RAC > 10%) followed by fly ash (10% < RAC < 30%) and desulfurization gypsum (1% < RAC < 10%). Additionally, we found that the implementation of pollution and carbon reduction policies in China had reduced Hg emissions from CFPPs by 45% from 2007 to 2015, increased the efficiency of Hg removal from APCDs to a maximum of 96%, and reduced global transport and health risk of atmospheric Hg. The results conjunctively achieved by CiteSpace, and the literature review will enhance understanding of CFPP Hg emission research and provide new perspectives for future research.
Topics: Mercury; Air Pollutants; Coal; Power Plants; China; Bibliometrics
PubMed: 38379043
DOI: 10.1007/s11356-024-32369-z -
Biometals : An International Journal on... Feb 2024The majority of the so-called heavy metals are suspected to be involved in a number of pathologies and play a role in human carcinogenesis. Some of them (i.e. arsenic... (Review)
Review
The majority of the so-called heavy metals are suspected to be involved in a number of pathologies and play a role in human carcinogenesis. Some of them (i.e. arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg) and nickel (Ni)) have been defined as carcinogens, increasing the susceptibility of tumor development and progression in humans. Moreover, Ni, Cr, Cd, Hg, and Pb together with zinc (Zn) and iron (Fe), may be capable of stimulating the progression of breast cancer and reducing a patient's sensitivity to treatment through alterations to DNA methylation. In patients with gastric cancers, levels of various heavy metals are augmented and hypothesized to amplify the expression of the human epidermal growth factor receptor type 2 gene. Cd may increase the risk of lung cancer development and have a negative impact on the overall survival of lung cancer patients. To investigate the relation between heavy metals in biological samples and risk, occurrence and survival cancer individuals, a comprehensive review work was performed, with a focus on breast, lung, prostate and gastric cancers. An extensive search strategy was devised to ensure relevant literature could be identified, with the PECO framework being adopted to facilitate this and identify key search terms. As evidenced in this review, there is substantial data to support the hypothesis that heavy metals influence tumor development and progression. Unluckily the number of papers dealing with the determination of metals directly in samples from cancer tissues is still rather limited, so we decided to expand the scope of this review also to analyses carried out on other biological samples, as urine, plasma, hair, nail, etc. The studies reviewed showed that several limitations and current knowledge gaps are present in the literature that require further investigation to improve our comprehension of the impact of different heavy metals on tumorigenesis.
PubMed: 38347295
DOI: 10.1007/s10534-024-00583-4 -
Journal of Neurochemistry Feb 2024Autism spectrum disorder (ASD) is characterized by repetitive behaviors and deficits in social interaction. Its etiology is not completely clear, but both genetic and... (Review)
Review
Autism spectrum disorder (ASD) is characterized by repetitive behaviors and deficits in social interaction. Its etiology is not completely clear, but both genetic and environmental factors contribute to and influence its development and course. The increased number of autism cases in recent years has been strongly associated with increased exposure to heavy metals. Mercury (Hg) has gained prominence in the scientific literature as a result of its presence as an urban pollutant and well-described neurotoxicity. This review assessed the relationship between Hg exposure in the pre- and post-natal period and ASD. The systematic review identified observational clinical studies and pre-clinical trials in journals indexed in the PubMed, Embase, ProQuest, and LILACS databases. The aim of this study was to investigate the association between exposure to Hg and ASD and to define the critical period of exposure. A total of 57 articles were selected for this review, with 35 articles (61.40%) identifying a positive association between ASD and Hg, while 22 articles (38.60%) did not find the same outcome. The biological samples most used to analyze Hg body burdens were hair (36.84%) and blood (36.84%). Most case-control studies found an increase in Hg levels in individuals with ASD who were exposed to a polluted environment in the post-natal period. Taken together, the studies suggest that these patients have a deficient detoxification system, and this could worsen the symptoms of the disorder. However, new studies addressing the influence of Hg on the post-natal nervous system and its relationship with ASD should be carried out.
PubMed: 38344837
DOI: 10.1111/jnc.16076 -
Frontiers in Cardiovascular Medicine 2024Cardiovascular diseases (CVDs) are the most important cause of premature death and disability worldwide. Environmental degradation and cardiovascular diseases are two...
INTRODUCTION
Cardiovascular diseases (CVDs) are the most important cause of premature death and disability worldwide. Environmental degradation and cardiovascular diseases are two keys to health challenges, characterized by a constant evolution in an industrialized world that exploits natural resources regardless of the consequences for health. The etiological risk factors of CVDs are widely known and include dyslipidemia, obesity, diabetes, and chronic cigarette consumption. However, one component that is often underestimated is exposure to heavy metals. The biological perspective explains that different metals play different roles. They are therefore classified into essential heavy metals, which are present in organisms where they perform important vital functions, especially in various physiological processes, or non-essential heavy metals, with a no biological role but, nonetheless, remain in the environment in which they are absorbed. Although both types of metal ions are many times chemically similar and can bind to the same biological ligands, the attention given today to nonessential metals in several eukaryotic species is starting to raise strong concerns due to an exponential increase in their concentrations. The aim of this systematic review was to assess possible correlations between exposure to nonessential heavy metals and increased incidence of cardiovascular disease, reporting the results of studies published in the last 5 years through March 2023.
METHODS
The studies includes reviews retrieved from PubMed, Medline, Embase, and Web of Science databases, in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement and following the PICO (Population Intervention Comparison Outcome Population) framework.
RESULTS
Eight reviews, including a total of 153 studies, were identified. Seven of these review enlighted the association between CVDs and non-essential heavy metals chronic exposure.
DISCUSSION
It is evident that exposure to heavy metals represent a risk factor for CVDs onset. However, further studies are needed to better understand the effects caused by these metals.
PubMed: 38322770
DOI: 10.3389/fcvm.2024.1332339 -
Environmental Research May 2024Metalloestrogens are metals and metalloid elements with estrogenic activity found everywhere. Their impact on human health is becoming more apparent as human activities... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Metalloestrogens are metals and metalloid elements with estrogenic activity found everywhere. Their impact on human health is becoming more apparent as human activities increase.
OBJECTIVE
Our aim is to conduct a comprehensive systematic review and meta-analysis of observational studies exploring the correlation between metalloestrogens (specifically As, Sb, Cr, Cd, Cu, Se, Hg) and Gestational Diabetes Mellitus (GDM).
METHODS
PubMed, Web of Science, and Embase were searched to examine the link between metalloestrogens (As, Sb, Cr, Cd, Cu, Se, and Hg) and GDM until December 2023. Risk estimates were derived using random effects models. Subgroup analyses were conducted based on study countries, exposure sample, exposure assessment method, and detection methods. Sensitivity analyses and adjustments for publication bias were carried out to assess the strength of the findings.
RESULTS
Out of the 389 articles identified initially, 350 met our criteria and 33 were included in the meta-analysis, involving 141,175 subjects (9450 cases, 131,725 controls). Arsenic, antimony, and copper exposure exhibited a potential increase in GDM risk to some extent (As: OR = 1.28, 95 % CI [1.08, 1.52]; Sb: OR = 1.73, 95 % CI [1.13, 2.65]; Cu: OR = 1.29, 95 % CI [1.02, 1.63]), although there is a high degree of heterogeneity (As: Q = 52.93, p < 0.05, I = 64.1 %; Sb: Q = 31.40, p < 0.05, I = 80.9 %; Cu: Q = 21.14, p < 0.05, I = 71.6 %). Conversely, selenium, cadmium, chromium, and mercury exposure did not exhibit any association with the risk of GDM in our study.
DISCUSSION
Our research indicates that the existence of harmful metalloestrogens in the surroundings has a notable effect on the likelihood of GDM. Hence, we stress the significance of environmental elements in the development of GDM and the pressing need for relevant policies and measures.
Topics: Pregnancy; Female; Humans; Diabetes, Gestational; Cadmium; Copper; Arsenic; Mercury; Observational Studies as Topic
PubMed: 38307186
DOI: 10.1016/j.envres.2024.118321 -
Cureus Jan 2024Tranexamic acid (TXA), a fibrinolytic agent, effectively inhibits plasminogen activation, thereby reducing fibrinolysis and hemorrhage. This study focused on its... (Review)
Review
Tranexamic acid (TXA), a fibrinolytic agent, effectively inhibits plasminogen activation, thereby reducing fibrinolysis and hemorrhage. This study focused on its application in trauma patients undergoing emergency surgery, a critical area due to trauma's significant role in mortality. Our investigation involved a meticulous screening of randomized controlled trials from databases including Scopus, PubMed, Web of Science, and Cochrane. The findings indicate that TXA intervention is promising in enhancing outcomes for trauma patients. However, the drug's effectiveness may vary based on the specific nature of the medical condition. In summary, robust evidence suggests that TXA can diminish blood loss, lower transfusion rates, reduce complications, and improve hemoglobin and hematocrit levels in surgical patients. Consequently, TXA should be considered a crucial medication, readily available to mitigate morbidity and mortality in surgical settings. Future research should explore factors influencing TXA's effectiveness in traumatic brain injury cases and across a broad spectrum of surgical scenarios in diverse patient populations. This would further guide clinicians in refining and optimizing the use of TXA.
PubMed: 38213943
DOI: 10.7759/cureus.52111