Environmental Metals and Cardiovascular Disease in Adults: A Systematic Review Beyond Lead and Cadmium

Published systematic reviews concluded that there is moderate to strong evidence to infer a potential role of lead and cadmium, widespread environmental metals, as cardiovascular risk factors. For other non-essential metals, the evidence has not been appraised systematically. Our objective was to systematically review epidemiologic studies on the association between cardiovascular disease in adults and the environmental metals antimony, barium, chromium, nickel, tungsten, uranium, and vanadium. We identified a total of 4 articles on antimony, 1 on barium, 5 on chromium, 1 on nickel, 4 on tungsten, 1 on uranium, and 0 on vanadium. We concluded that the current evidence is not sufficient to inform on the cardiovascular role of these metals because of the small number of studies. Few experimental studies have also evaluated the role of these metals in cardiovascular outcomes. Additional epidemiologic and experimental studies, including prospective cohort studies, are needed to understand the role of metals, including exposure to metal mixtures, in cardiovascular disease development.

Declining exposures to lead and cadmium contribute to explaining the reduction of cardiovascular mortality in the US population, 1988-2004

Background

Lead and cadmium exposures have markedly declined in the USA following the implementation of large-scale public health policies and could have contributed to the unexplained decline in cardiovascular mortality in US adults. We evaluated the potential contribution of lead and cadmium exposure reductions to explain decreasing cardiovascular mortality trends occurring in the USA from 1988-94 to 1999-2004.

Methods

Prospective study in 15 421 adults ≥40 years old who had participated in the National Health and Nutrition Examination Survey 1988-94 or 1999-2004. We estimated the amount of change in cardiovascular mortality over time that can be independently attributed to the intermediate pathway of changes in blood lead and urine cadmium concentrations.

Results

There was a 42.0% decrease in blood lead and a 31.0% decrease in urine cadmium concentrations. The cardiovascular mortality rate ratio [95% confidence intervals (CIs)] associated with a doubling of metal levels was 1.19 (1.07, 1.31) for blood lead and 1.20 (1.09, 1.32) for urine cadmium. The absolute reduction in cardiovascular deaths comparing 1999-2004 to 1988-94 was 230.7 deaths/100 000 person-years, in models adjusted for traditional cardiovascular risk factors. Among these avoided deaths, 52.0 (95% CI 8.4, 96.7) and 19.4 (4.3, 36.4) deaths/100 000 person-years were attributable to changes in lead and cadmium, respectively.

Conclusions

Environmental declines in lead and cadmium exposures were associated with reductions in cardiovascular mortality in US adults. Given the fact that lead and cadmium remain associated with cardiovascular disease at relatively low levels of exposure, prevention strategies that further minimize exposure to lead and cadmium may be needed.

Possible involvement of orphan receptors GPR88 and GPR124 in the development of hypertension in spontaneously hypertensive rat

Hypertension (HBP) is a chronic disease characterized by increased blood pressure, which despite several treatments maintains a high morbi-mortality, which suggests that there are other mechanisms involved in this pathology, within which the orphan receptors could be candidates for the treatment of the HBP; these receptors are called orphan receptors because their ligand is unknown. These receptors have been suggested to participate in some pathologies because they are associated with various systems such as GPR88, which has been linked to the dopaminergic system, and GPR124 with angiogenesis, suggesting that these receptors could take part in HBP. Hence, the aim of this work was to study the expression of orphan receptors GPR88 and GPR124 in various tissues of normotensive and hypertensive rats. We used Wistar Kyoto (WKY) and spontaneously hypertensive rat (SHR) of 6-8 and 10-12 weeks of age and we determined systolic blood pressure (SBP), heart rate, as well as mRNA of GPR88 and GPR124 receptors by reverse transcription polymerase chain reaction (RT-PCR) in the aorta, heart, kidney, and brain. Our results showed that GPR88 and GPR124 were expressed in all analyzed tissues, but their expression is dependent on the age and development of HBP because their expression tends to be modified as HBP is established. Therefore, we conclude that GPR88 and GPR124 receptors may be involved in the development or maintenance of high blood pressure.

Environmental chemicals and DNA methylation in adults: a systematic review of the epidemiologic evidence

Current evidence supports the notion that environmental exposures are associated with DNA-methylation and expression changes that can impact human health. Our objective was to conduct a systematic review of epidemiologic studies evaluating the association between environmental chemicals with DNA methylation levels in adults. After excluding arsenic, recently evaluated in a systematic review, we identified a total of 17 articles (6 on cadmium, 4 on lead, 2 on mercury, 1 on nickel, 1 on antimony, 1 on tungsten, 5 on persistent organic pollutants and perfluorinated compounds, 1 on bisphenol A, and 3 on polycyclic aromatic hydrocarbons). The selected articles reported quantitative methods to determine DNA methylation including immunocolorimetric assays for total content of genomic DNA methylation, and microarray technologies, methylation-specific quantitative PCR, Luminometric Methylation Assay (LUMA), and bisulfite pyrosequencing for DNA methylation content of genomic sites such as gene promoters, LINE-1, Alu elements, and others. Considering consistency, temporality, strength, dose-response relationship, and biological plausibility, we concluded that the current evidence is not sufficient to provide inference because differences across studies and limited samples sizes make it difficult to compare across studies and to evaluate sources of heterogeneity. Important questions for future research include the need for larger and longitudinal studies, the validation of findings, and the systematic evaluation of the dose-response relationships. Future studies should also consider the evaluation of epigenetic marks recently in the research spotlight such as DNA hydroxymethylation and the role of underlying genetic variants.

Environmental chemicals and DNA methylation in adults: a systematic review of the epidemiologic evidence

Current evidence supports the notion that environmental exposures are associated with DNA-methylation and expression changes that can impact human health. Our objective was to conduct a systematic review of epidemiologic studies evaluating the association between environmental chemicals with DNA methylation levels in adults. After excluding arsenic, recently evaluated in a systematic review, we identified a total of 17 articles (6 on cadmium, 4 on lead, 2 on mercury, 1 on nickel, 1 on antimony, 1 on tungsten, 5 on persistent organic pollutants and perfluorinated compounds, 1 on bisphenol A, and 3 on polycyclic aromatic hydrocarbons). The selected articles reported quantitative methods to determine DNA methylation including immunocolorimetric assays for total content of genomic DNA methylation, and microarray technologies, methylation-specific quantitative PCR, Luminometric Methylation Assay (LUMA), and bisulfite pyrosequencing for DNA methylation content of genomic sites such as gene promoters, LINE-1, Alu elements, and others. Considering consistency, temporality, strength, dose-response relationship, and biological plausibility, we concluded that the current evidence is not sufficient to provide inference because differences across studies and limited samples sizes make it difficult to compare across studies and to evaluate sources of heterogeneity. Important questions for future research include the need for larger and longitudinal studies, the validation of findings, and the systematic evaluation of the dose-response relationships. Future studies should also consider the evaluation of epigenetic marks recently in the research spotlight such as DNA hydroxymethylation and the role of underlying genetic variants.