-
Environmental Research Jul 2017Several populations are exposed to mercury (Hg) via their environment, occupation or diet. It is hypothesized that Hg exposure can lead to the development of diabetes... (Review)
Review
INTRODUCTION
Several populations are exposed to mercury (Hg) via their environment, occupation or diet. It is hypothesized that Hg exposure can lead to the development of diabetes mellitus (DM). Metabolic syndrome (MS) is also a possible outcome as its symptoms are closely linked to those of DM.
METHOD
We conducted a systematic review of the literature by screening Web of Science, MEDLINE, SciFinder and Embase and we included original studies pertaining to the relationship of total Hg exposure (elemental, inorganic or organic) to DM, MS or insulin resistance. The studies were selected based on the PICOS (patients, intervention, comparator, outcomes and study design) criteria and their quality assessed using a nine-point scale. Study characteristics and results were extracted and presented in structured tables. We also extracted covariates entered as confounding factors to evaluate possible biases in selected studies. Finally, a weight of evidence approach was used to assess the causality of the relationship.
RESULTS
A total of 34 studies were included in the present review. Epidemiological data assessment suggests a possible association between total Hg concentrations in different biological matrices and incidence of DM or MS, but the relationship is not consistent. In vivo and in vitro studies support the biological plausibility of the relation between Hg exposure and DM or MS. Five out of nine of Bradford Hill's criteria were fulfilled: strength, temporality, plausibility, coherence and analogy.
CONCLUSION
Increased total Hg exposure may augment the risk of DM and MS, but the lack of consistency of the epidemiological evidence prevents inference of a causal relationship. Additional prospective cohort studies and careful consideration of confounding variables and interactions are required to conclude on the causal relationship of total Hg exposure on the development of DM or MS.
Topics: Animals; Diabetes Mellitus; Environmental Exposure; Environmental Pollutants; Humans; Insulin Resistance; Mercury; Metabolic Syndrome
PubMed: 28482296
DOI: 10.1016/j.envres.2017.04.038 -
Osteoporosis International : a Journal... Sep 2020The relationship between heavy metal exposure and risk of osteopenia or osteoporosis has biological plausibility, yet it remains inconclusive; therefore, we conducted a... (Meta-Analysis)
Meta-Analysis Review
The relationship between heavy metal exposure and risk of osteopenia or osteoporosis has biological plausibility, yet it remains inconclusive; therefore, we conducted a systematic review and meta-analysis to evaluate the associations between exposure to heavy metals (i.e., cadmium, lead, and mercury) and the risk of osteopenia or osteoporosis. Databases of MEDLINE, Embase, Scopus, and Web of Science were searched through November 2019, to identify studies that evaluated the relationship between exposure to cadmium, lead, and mercury and risk of osteopenia or osteoporosis in adults. Fourteen eligible studies were included. Effect sizes expressed as pooled odds ratios (OR) and 95% confidence intervals (CI) were estimated using weighted random-effect models. Exposure to cadmium (OR = 1.35; 95% CI: 1.17 to 1.56; P ≤ 0.001) and lead (OR = 1.15; 95% CI: 1.00 to 1.32; P = 0.05) was associated with an increased risk of osteopenia or osteoporosis, unlike mercury. Subgroup analyses showed cadmium exposure increased the risk of osteopenia or osteoporosis in older (> 65 yrs.; OR = 1.43; 95%CI: 1.08 to 1.88, P = 0.01) compared with younger (18-65 yrs.; OR = 1.24; 95% CI: 1.02 to 1.52, P = 0.03) adults. Also, lead exposure increased the risk in men (OR = 1.55; 95% CI: 1.15 to 2.09, P = 0.007) unlike in women. By contrast to urinary levels, blood (OR = 1.26; 95% CI: 1.08 to 1.47, P = 0.003) and dietary (OR = 1.46; 95% CI: 1.28 to 1.67, P < 0.001) levels of cadmium were associated with an increased risk of osteopenia or osteoporosis. Exposure to cadmium and lead may be associated with an increased risk of osteopenia or osteoporosis, although high heterogeneity was detected.
Topics: Adult; Aged; Bone Diseases, Metabolic; Cadmium; Female; Humans; Male; Mercury; Metals, Heavy; Osteoporosis
PubMed: 32361950
DOI: 10.1007/s00198-020-05429-6 -
Environmental Health Perspectives Aug 2023Neural tube defects (NTDs) affect pregnancies worldwide annually. Few nongenetic factors, other than folate deficiency, have been identified that may provide... (Review)
Review
BACKGROUND
Neural tube defects (NTDs) affect pregnancies worldwide annually. Few nongenetic factors, other than folate deficiency, have been identified that may provide intervenable solutions to reduce the burden of NTDs. Prenatal exposure to toxic metals [arsenic (As), cadmium (Cd), mercury (Hg), manganese (Mn) and lead (Pb)] may increase the risk of NTDs. Although a growing epidemiologic literature has examined associations, to our knowledge no systematic review has been conducted to date.
OBJECTIVE
Through adaptation of the Navigation Guide systematic review methodology, we aimed to answer the question "does exposure to As, Cd, Hg, Mn, or Pb during gestation increase the risk of NTDs?" and to assess challenges to evaluating this question given the current evidence.
METHODS
We selected available evidence on prenatal As, Cd, Hg, Mn, or Pb exposure and risk of specific NTDs (e.g., spina bifida, anencephaly) or all NTDs via a comprehensive search across MEDLINE, Embase, Web of Science, and TOXLINE databases and applied inclusion/exclusion criteria. We rated the quality and strength of the evidence for each metal. We applied a customized risk of bias protocol and evaluated the sufficiency of evidence of an effect of each metal on NTDs.
RESULTS
We identified 30 studies that met our criteria. Risk of bias for confounding and selection was high in most studies, but low for missing data. We determined that, although the evidence was limited, the literature supported an association between prenatal exposure to Hg or Mn and increased risk of NTDs. For the remaining metals, the evidence was inadequate to establish or rule out an effect.
CONCLUSION
The role of gestational As, Cd, or Pb exposure in the etiology of NTDs remains unclear and warrants further investigation in high-quality studies, with a particular focus on controlling confounding, mitigating selection bias, and improving exposure assessment. https://doi.org/10.1289/EHP11872.
Topics: Female; Pregnancy; Humans; Cadmium; Lead; Prenatal Exposure Delayed Effects; Neural Tube Defects; Mercury; Manganese; Arsenic
PubMed: 37647124
DOI: 10.1289/EHP11872 -
Biological Trace Element Research Nov 2022It has been reported that heavy metals have adverse effects on the immune system. However, the relationship between heavy metal exposure and allergic outcomes remains... (Meta-Analysis)
Meta-Analysis Review
It has been reported that heavy metals have adverse effects on the immune system. However, the relationship between heavy metal exposure and allergic outcomes remains unclear. This systematic review was conducted to examine whether heavy metal exposure is associated with allergic outcomes during childhood. We performed a systematic search of all relevant articles in Web of Science, EMBASE, and PubMed, from inception through to November 2020. We used odds ratio (OR) and the standard mean differences (SMDs) with 95% confidence intervals (CIs) to present estimates from individual studies. In addition, random-effects meta-analysis was used to pool the data. We also conducted the meta-regression and subgroup analysis to explore potential sources of heterogeneity. After duplicate removal, we finally included 35 articles in the systematic review and meta-analysis from an initial 11,181 articles. The overall results showed that copper (Cu) was associated with asthma (pooled SMD = 1.50, 95% CI = 0.13-2.86); in the subgroup analysis, the results indicated that lead (Pb) was associated with asthma (pooled OR = 6.27, 95% CI = 2.24-17.56), and Cu and Pb were connected with atopic dermatitis (SMD = - 1.05, 95% CI = - 1.45 to - 0.65; SMD = 5.68, 95% CI = 5.05-6.32), respectively. Mercury (Hg) was associated with atopic dermatitis (pooled OR = 1.13, 95% CI = 1.04-1.22) and wheeze (OR = 1.20, 95% CI = 1.05-1.37). The meta-analysis results indicate that Cu might be connected with childhood asthma, but not with other allergic diseases; Hg and Pb may have no association with allergic diseases during childhood. Given some limits observed in the current studies, more prospective cohort studies are still needed to verify our findings. Review registration: PROSPERO CRD42020222167.
Topics: Asthma; Child; Copper; Dermatitis, Atopic; Humans; Lead; Mercury; Metals, Heavy; Prospective Studies
PubMed: 35006554
DOI: 10.1007/s12011-021-03070-w -
Antioxidants (Basel, Switzerland) Jul 2023Altered levels of heavy metals and essential elements have been associated with oxidative stress (OS) and metabolic and hormonal changes in women with polycystic ovary... (Review)
Review
Altered levels of heavy metals and essential elements have been associated with oxidative stress (OS) and metabolic and hormonal changes in women with polycystic ovary syndrome (PCOS). We aimed to summarize the knowledge on the association of heavy metals and essential elements with OS in PCOS. An electronic literature search using PubMed for studies published between January 2008 and April 2023 was conducted. We evaluated heavy metals and essential elements in relation to OS in PCOS in 15 articles. PCOS women had increased antimonium (Sb), cadmium (Cd), lead (Pb), mercury (Hg), arsenic (As), tellurium (Te), thallium (Tl) and osmium (Os) blood levels and decreased zinc (Zn) blood levels; the results of copper (Cu) blood levels were conflicting. Some studies showed a significant correlation between heavy metals (Sb, Cd, Pb, Hg, As, Te and Tl) and essential elements (Se, Zn, Cr, Ca, Mg and Cu) and markers of OS and chronic inflammation. Heavy metals (Sb, Cd, Pb and Hg) and essential elements (Zn, Cr, Se, Ca, Mg and Cu) were associated with metabolic and hormonal characteristics in PCOS. There might be a possible benefit from supplementation therapy in reducing OS and endocrinological problems related to PCOS. Our review confirmed an association between heavy metals and essential elements with OS in PCOS women. This systematic review is registered in PROSPERO under number CRD42023418453.
PubMed: 37507937
DOI: 10.3390/antiox12071398 -
Journal of Hypertension Feb 2017The phase-out of mercury from clinical settings calls for valid alternatives to assess blood pressure (BP) in children. Aneroid devices provide a mercury-free... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
The phase-out of mercury from clinical settings calls for valid alternatives to assess blood pressure (BP) in children. Aneroid devices provide a mercury-free alternative to BP measurements by auscultation, whereas oscillometric (automated) devices are increasingly becoming the norm in clinical practice due to their ease of use. The aim of this systematic review and meta-analysis was to investigate the accuracy of oscillometric and aneroid BP devices compared with the mercury sphygmomanometer for the measurement of BP in children.
METHODS
We systematically searched four electronic databases (MEDLINE, Embase, CINAHL, and Web of Science) and relevant journals for eligible articles published before 30 July 2015. We screened 1415 articles, and two authors independently reviewed 92 full-text articles.
RESULTS
We included 29 articles (38 studies) with 26 879 children. Random-effects model meta-analyses revealed that oscillometric devices yield higher measurements of SBP than auscultation with a mercury sphygmomanometer (pooled effect estimate 2.53 mmHg; 95% CI 0.57-4.50; P < 0.05); the pooled effect estimate for SBP was smaller in studies that 'passed' validation protocols (1.76 mmHg; 95% CI 0.61-2.81; n = 12). There was no significant difference for DBP (pooled effect estimate 1.55 mmHg; 95% CI -0.20 to 3.31). There was heterogeneity between studies, explained in part by differences in manufacturer, study setting and observer training. Only three studies compared BP using aneroid and mercury devices and found comparable results.
CONCLUSION
Oscillometric devices may serve as a suitable alternative to auscultation for initial BP screening in the pediatric population.
Topics: Auscultation; Blood Pressure; Blood Pressure Determination; Child; Humans; Oscillometry; Reproducibility of Results; Sphygmomanometers
PubMed: 27870656
DOI: 10.1097/HJH.0000000000001178 -
Environmental Health : a Global Access... Nov 2023Early life exposure to lead, mercury, polychlorinated biphenyls (PCBs), polybromide diphenyl ethers (PBDEs), organophosphate pesticides (OPPs), and phthalates have been... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Early life exposure to lead, mercury, polychlorinated biphenyls (PCBs), polybromide diphenyl ethers (PBDEs), organophosphate pesticides (OPPs), and phthalates have been associated with lowered IQ in children. In some studies, these neurotoxicants impact males and females differently. We aimed to examine the sex-specific effects of exposure to developmental neurotoxicants on intelligence (IQ) in a systematic review and meta-analysis.
METHOD
We screened abstracts published in PsychINFO and PubMed before December 31st, 2021, for empirical studies of six neurotoxicants (lead, mercury, PCBs, PBDEs, OPPs, and phthalates) that (1) used an individualized biomarker; (2) measured exposure during the prenatal period or before age six; and (3) provided effect estimates on general, nonverbal, and/or verbal IQ by sex. We assessed each study for risk of bias and evaluated the certainty of the evidence using Navigation Guide. We performed separate random effect meta-analyses by sex and timing of exposure with subgroup analyses by neurotoxicant.
RESULTS
Fifty-one studies were included in the systematic review and 20 in the meta-analysis. Prenatal exposure to developmental neurotoxicants was associated with decreased general and nonverbal IQ in males, especially for lead. No significant effects were found for verbal IQ, or postnatal lead exposure and general IQ. Due to the limited number of studies, we were unable to analyze postnatal effects of any of the other neurotoxicants.
CONCLUSION
During fetal development, males may be more vulnerable than females to general and nonverbal intellectual deficits from neurotoxic exposures, especially from lead. More research is needed to examine the nuanced sex-specific effects found for postnatal exposure to toxic chemicals.
Topics: Child; Pregnancy; Humans; Male; Female; Polychlorinated Biphenyls; Lead; Sex Characteristics; Halogenated Diphenyl Ethers; Mercury; Insecticides; Organophosphorus Compounds; Prenatal Exposure Delayed Effects
PubMed: 37978510
DOI: 10.1186/s12940-023-01029-z -
Occupational Medicine (Oxford, England) Dec 2017The waste and recycling sector is a growing part of industry. Whether health surveillance is indicated and how it should be undertaken is unclear. (Review)
Review
BACKGROUND
The waste and recycling sector is a growing part of industry. Whether health surveillance is indicated and how it should be undertaken is unclear.
AIMS
To undertake a review of the literature to identify hazards to health, biological effects and occupational illnesses for workers in the sector.
METHODS
A systematic review of the published literature and two UK databases.
RESULTS
Rates of fatal, non-fatal injuries and self-reported work-related illness were found to be higher in the waste and recycling sector than in UK industry as a whole. There was an increased prevalence of respiratory, gastro-intestinal and skin complaints in workers exposed to compost relative to controls. They may also be at increased risk of extrinsic allergic alveolitis, allergic bronchopulmonary aspergillosis, occupational asthma and abnormalities of lung function. Workers involved with the recycling of batteries and cables may be at risk of lead poisoning and exposure to other heavy metals. There were case reports of mercury poisoning from the recycling of fluorescent lights. Cases of occupational asthma have been reported in association with wood and paper recycling. The recycling of e-waste may cause exposure to heavy metals and organic pollutants, such as polybrominated diphenyl ethers, dioxins and polyaromatic hydrocarbons, which have been associated with damage to DNA and adverse neonatal outcomes.
CONCLUSIONS
Ill-health and adverse biological effects have been described in waste and recycling workers, but their true prevalence has probably not been captured. Targeted health surveillance may be required to assess exposure and to identify occupational illness.
Topics: Humans; Manufacturing Industry; Occupational Diseases; Prevalence; Recycling; Waste Disposal Facilities; Workforce
PubMed: 29165683
DOI: 10.1093/occmed/kqx153 -
Autoimmunity Reviews Jan 2017Autoimmune diseases result from an interplay of genetic predisposition and factors which stimulate the onset of disease. Mercury (Hg), a well-established toxicant, is an... (Review)
Review
Autoimmune diseases result from an interplay of genetic predisposition and factors which stimulate the onset of disease. Mercury (Hg), a well-established toxicant, is an environmental factor reported to be linked with autoimmunity. Hg exists in several chemical forms and is encountered by humans in dental amalgams, certain vaccines, occupational exposure, atmospheric pollution and seafood. Several studies have investigated the effect of the various forms of Hg, including elemental (Hg), inorganic (iHg) and organic mercury (oHg) and their association with autoimmunity. In vitro studies using peripheral blood mononuclear cells (PBMC) from healthy participants have shown that methylmercury (MeHg) causes cell death at lower concentrations than iHg albeit exposure to iHg results in a more enhanced pro-inflammatory profile in comparison to MeHg. In vivo research utilising murine models susceptible to the development of metal-induced autoimmunity report that exposure to iHg results in a lupus-like syndrome, whilst mice exposed to MeHg develop autoimmunity without the formation of immune complexes. Furthermore, lower concentrations of IgE are detected in MeHg-treated animals in comparison with those treated with iHg. It appears that, oHg has a negative impact on animal models with existing autoimmunity. The research conducted on humans in this area is diverse in study design and the results are conflicting. There is currently no evidence to implicate a role for Hg exposure from dental amalgams in the development or perpetuation of autoimmune disease, apart from some suggestion of individual sensitivity. Several studies have consistently shown a positive correlation between iHg exposure and serum autoantibody concentrations in gold miners, although the clinical impact of iHg remains unknown. Furthermore, a limited number of studies have reported individuals with autoimmune disease have higher concentrations of blood Hg compared to healthy controls. In summary, it appears that iHg perpetuates markers of autoimmunity to a greater extent than oHg, albeit the impact on clinical outcomes in humans is yet to be elucidated.
Topics: Animals; Autoimmune Diseases; Autoimmunity; Environmental Exposure; Environmental Pollutants; Humans; Leukocytes, Mononuclear; Mercury
PubMed: 27666813
DOI: 10.1016/j.autrev.2016.09.020