Ischemic Heart Disease Incidence in Relation to Fine versus Total Particulate Matter Exposure in a U.S. Aluminum Industry Cohort

A review of the epidemiological and laboratory evidence of the role of aluminum exposure in pathogenesis of cardiovascular diseases

The objective of the present study was to review the epidemiological and laboratory evidence on the role of aluminum (Al) exposure in the pathogenesis of cardiovascular diseases. Epidemiological data demonstrated an increased incidence of cardiovascular diseases (CVD), including hypertension and atherosclerosis in occupationally exposed subjects and hemodialysis patients. In addition, Al body burden was found to be elevated in patients with coronary heart disease, hypertension, and dyslipidemia. Laboratory studies demonstrated that Al exposure induced significant ultrastructural damage in the heart, resulting in electrocardiogram alterations in association with cardiomyocyte necrosis and apoptosis, inflammation, oxidative stress, inflammation, and mitochondrial dysfunction. In agreement with the epidemiological findings, laboratory data demonstrated dyslipidemia upon Al exposure, resulting from impaired hepatic lipid catabolism, as well as promotion of low-density lipoprotein oxidation. Al was also shown to inhibit paraoxonase 1 activity and to induce endothelial dysfunction and adhesion molecule expression, further promoting atherogenesis. The role of Al in hypertension was shown to be mediated by up-regulation of NADPH-oxidase, inhibition of nitric oxide bioavailability, and stimulation of renin-angiotensin-aldosterone system. It has been also demonstrated that Al exposure targets cerebral vasculature, which may be considered a link between Al exposure and cerebrovascular diseases. Findings from other tissues lend support that ferroptosis, pyroptosis, endoplasmic reticulum stress, and modulation of gut microbiome and metabolome are involved in the development of CVD upon Al exposure. A better understanding of the role of the cardiovascular system as a target for Al toxicity will be useful for risk assessment and the development of treatment and prevention strategies.

Disparities in job characteristics by race and sex in a Southern aluminum smelting facility

BACKGROUND

Former workers at a Southern aluminum smelting facility raised concerns that the most hazardous jobs were assigned to Black workers, but the role of workplace segregation had not been quantified or examined in the company town. Prior studies discuss race and gender disparities in working conditions, but few have documented them in the aluminum industry.

METHODS

We obtained workers' company records for 1985-2007 and characterized four job metrics: prestige (sociologic rankings), worker-defined danger (worker assessments), annual wage (1985 dollars), and estimated total particulate matter (TPM) exposure (job exposure matrix). Characteristics of job at hire and trajectories were compared by race and sex using linear binomial models.

RESULTS

Non-White males had the highest percentage of workers in low prestige and high danger jobs at hire and up to 20 years after. After 20 years tenure, 100% of White workers were in higher prestige and lower danger jobs. Most female workers, regardless of race, entered and remained in low-wage jobs, while 50% of all male workers maintained their initial higher-wage jobs. Non-White females had the highest prevalence of workers in low-wage jobs at hire and after 20 years-increasing from 63% (95% CI: 59-67) to 100% (95% CI: 78-100). All female workers were less likely to be in high TPM exposure jobs. Non-White males were most likely to be hired into high TPM exposure jobs, and this exposure prevalence increased as time accrued, while staying constant for other race-sex groups.

CONCLUSIONS

There is evidence of job segregation by race and sex in this cohort of aluminum smelting workers. Documentation of disparities in occupational hazards is important for informing health interventions and research.

A facile approach for the preparation of polycarbonate nanofiber mat with filtration capability

The present day environmental issues demand a lot from scientists and engineers to keep the planet earth safe for its habitats. There were lot of attempts for developing efficient air and liquid filters as the demand increases with an utmost concern of present environmental situations. Thanks to its large surface area to volume ratio, polymer nanofibers and composites are found to be good substitute for conventional filters. As per the research and analysis data, filtration efficiency increases proportional to the reduction of the average diameter of the fibers. In this study, the most efficient electrospinning technology was adopted to prepare polycarbonate (PC) nanofiber mat which yields a very fine surface morphology. There are earlier researches and associated data available about the preparation of PC nanofibers but with average fiber diameter above 1000 nm. In this study, a systematic methodology was instigated to generate PC nanofibers with least average diameter of 90 nm without using any surfactants or salts. The most suitable solvents, solvent proportion, polymer concentration and electrospinning conditions for the formation of the fiber mat are discussed elaborately. PC fiber mat of least average diameter was proved to be highly efficient for particulate matter adsorption using a dust sampling analyzer.

Synergistic effect of cranberry extract and losartan against aluminium chloride-induced hepatorenal damage associated cardiomyopathy in rats

The present study was designed to evaluate the effect of cranberry extract (CRAN) and/or losartan (LOS) against aluminium chloride (AlCl₃) induced hepatorenal damage associated cardiomyopathy in rats. To induce hepatorenal and cardiotoxicity, animals were received (AlCl₃; 70 mg/kg i.p.) for 8 weeks day after day and treated with CRAN (100 mg/kg b.wt.) orally daily for 4 weeks started after 4 weeks from AlCl₃ injection accompanied with an administration of LOS (5 mg/kg i.p.) three times weekly for 4 weeks. Our data revealed that, compared to AlCl₃, administration of CRAN extract and LOS produced a significant improvement which was evidenced by a significant amelioration in myocardial and vascular indices, kidney and liver markers, lipid profile and oxidative stress indices. Furthermore, histopathological and immunohistochemical examination reinforced the previous results. It could be concluded that combination of CRAN extract and LOS hindered AlCl₃ induced hepatorenal damage complicated cardiomyopathy in rats.

Egg White Hydrolysate: A new putative agent to prevent vascular dysfunction in rats following long-term exposure to aluminum

Aluminum (Al) is toxic for humans and animals. Here, we have tested the potential for Egg White Hydrolysate (EWH) to protect against cardiovascular changes in rats exposed to both high and low dietary levels of Al. Indeed, EWH has been previously shown to improve cardio metabolic dysfunctions induced by chronic exposure to heavy metals. Male Wistar rats received orally: Group 1) Low aluminum level (AlCl₃ at a dose of 8.3 mg/kg b.w. during 60 days) with or without EWH treatment (1 g/kg/day); Group 2) High aluminum level (AlCl₃ at a dose of 100 mg/kg b.w. during 42 days) with or without EWH treatment. After Al treatment, rats co-treated with EWH did not show vascular dysfunction or increased blood pressure as was observed in non EWH-cotreated animals. Indeed, co-treatment with EWH prevented the following effects observed in both aorta and mesenteric arteries: the increased vascular responses to phenylephrine (Phe), the decreased ACh-induced relaxation, the reduction on endothelial modulation of vasoconstrictor responses and the nitric oxide bioavailability, as well as the increased reactive oxygen species production from NAD(P)H oxidase. Altogether, our results suggest that EWH could be used as a protective agent against the harmful vascular effects after long term exposure to Al.

Associations of multiple plasma metals with the risk of ischemic stroke: A case-control study

BACKGROUND

Ischemic stroke (IS) is a major cause of morbidity and mortality globally. Environmental exposure to metals may be linked to the risk of IS, but the association remains uncertain in Chinese populations.

OBJECTIVES

The present study aimed to examine the associations between the concentrations of 11 metals (aluminum, arsenic, cadmium, cobalt, copper, iron, manganese, molybdenum, selenium, thallium, and zinc) in plasma and the risk of IS in a Chinese population.

METHODS

A total of 1277 pairs of newly diagnosed IS patients and controls matched on age (±3 years) and sex were recruited in our study. Plasma metal concentrations were measured using inductively coupled plasma mass spectrometry. Multivariable conditional logistic regression models were conducted to investigate the impacts of single and multiple metals, respectively.

RESULTS

In the single-metal model, exposure to seven metals (aluminum, arsenic, cadmium, cobalt, iron, manganese and selenium) was individually associated with the risk of IS based on the trend test. Further stepwise regression analyses with the multiple-metal model revealed increasing trends in the risk of IS associated with aluminum, arsenic, and cadmium quartiles and decreasing trends with iron and selenium quartiles (p-trend < 0.01). Compared to the lowest quartiles, the odds ratios (95% confidence intervals) for the highest quartiles of these five metals were 4.23 (2.63, 6.79), 1.88 (1.25, 2.81), 5.02 (3.30, 7.63), 0.59 (0.40, 0.89), and 0.10 (0.06, 0.17), respectively.

CONCLUSIONS

Our study suggested that higher plasma concentrations of aluminum, arsenic, and cadmium, and lower concentrations of iron and selenium may increase the risk of IS. Further prospective studies in larger populations are warranted to confirm our findings.

Ambient Fine Aerosol Concentrations in Multiple Metrics in Taconite Mining Operations

Studies in environmental epidemiology and of occupational cohorts have implicated the effects of fine particulates with increased risk of cardiovascular diseases. Motivated by this evidence, we conducted an ambient air monitoring campaign to characterize fine aerosol concentrations around various taconite ore processes in six taconite mines in northeastern Minnesota. The ore processes were first categorized into 16 broad work areas/buildings. We then took air samples at 91 fixed locations using an array of direct-reading instruments to obtain measurements of mass (PM2.5 or particles with aerodynamic diameter <2.5 µm, and respirable particulate matter or RPM), alveolar-deposited surface area (ADSA), and particle number (PN) concentrations. At each location, a respirable gravimetric pump (which was used for calibration purposes) and the instruments measured the ambient dust level for 4 h producing ~240 1-min averaging real-time measurements. To analyze these data, we fit a Bayesian hierarchical model with an autoregressive order 1 correlation structure to estimate pooled concentrations for the 16 work areas/buildings while accounting for temporal correlation. PM2.5 and RPM average ambient concentrations were highly correlated to each other (Pearson's correlation = 0.98), followed by ADSA and PN correlation (R = 0.77). Office and control room areas were found to have the lowest concentrations in all four metrics when compared to other groups. Distinguishing between concentration levels among the remaining groups was more difficult due to the high uncertainty associated with the geometric mean estimates. The geometric standard deviation within location (GSDWL) generally ranged from 1 to 3 for all exposure metrics, except for a few locations that may have had changes in the work activities that generated the observed peaks and variability during the sampling duration. The geometric standard deviation between locations estimates were generally higher than GSDWL, which may indicate larger variability in the processes/activities between locations within each broad work area/building. Future work may look into whether it is feasible to use area measurements for epidemiological investigation and use personal measurements (if available) to validate such approach.

Association of Serum Aluminum Levels with Mortality in Patients on Chronic Hemodialysis

Despite reported evidence on the relationship between higher serum aluminum levels and poor outcomes in patients on chronic hemodialysis (CHD), the acceptable cutoff value of serum aluminum for mortality remains unclear. A retrospective observational cohort study with 636 Taiwanese patients on CHD was conducted to investigate the impact of serum aluminum levels on mortality. The predictors were bivariate serum aluminum level (<6 and ≥6 ng/mL) and the Outcomes were all-cause and cardiovascular (CV) mortality. During the mean follow-up of 5.3 ± 2.9 years, 253 all-cause and 173 CV deaths occurred. Crude analysis showed that a serum aluminum level of ≥6 ng/mL was a significant predictor of all-cause [hazard ratio (HR), 1.80; 95% confidence interval (CI), 1.40–2.23] and CV (HR, 1.84; 95% CI, 1.36–2.50) mortality. After multivariable adjustment, the serum aluminum level of ≥6 ng/mL remained a significant predictor of all-cause mortality (HR, 1.37, 95% CI, 1.05–1.81) but became insignificant for CV mortality (HR, 1.29; 95% CI, 0.92–1.81). Therefore, our study revealed that a serum aluminum level of ≥6 ng/mL was independently associated with all-cause death in patients on CHD, suggesting that early intervention for aluminum level in patients on CHD might be beneficial even in the absence of overt aluminum toxicity.

Cytotoxicity of Air Pollutant 9,10-Phenanthrenequinone: Role of Reactive Oxygen Species and Redox Signaling

Atmospheric pollution has been a principal topic recently in the scientific and political community due to its role and impact on human and ecological health. 9,10-phenanthrenequinone (9,10-PQ) is a quinone molecule found in air pollution abundantly in the diesel exhaust particles (DEP). This compound has studied extensively and has been shown to develop cytotoxic effects both in vitro and in vivo. 9, 10-PQ has been proposed to play a critical role in the development of cytotoxicity via generation of reactive oxygen species (ROS) through redox cycling. This compound also reduces expression of glutathione (GSH), which is critical in Phase II detoxification reactions. Understanding the underlying cellular mechanisms involved in cytotoxicity can allow for the development of therapeutics designed to target specific molecules significantly involved in the 9,10-PQ-induced ROS toxicity. This review highlights the developments in the understanding of the cytotoxic effects of 9, 10-PQ with special emphasis on the possible mechanisms involved.

Association between serum aluminum levels and cardiothoracic ratio in patients on chronic hemodialysis

The cardiothoracic ratio (CTR) and serum aluminum levels are both associated with mortality in hemodialysis patients. However, limited data regarding the association between serum aluminum levels and the CTR have been published to date. Therefore, we aimed to elucidate this association in patients on chronic hemodialysis (CHD). We investigated the association between the serum aluminum level and the CTR in CHD in a retrospective cross-sectional study of 547 Taiwanese patients on CHD. The mean age of patients was 62.5±13.2 years, with a mean hemodialysis time of 7.1±5.2 years. Among the patients, 36.9% were diabetic and 47.9% were male. After natural logarithmic transformation (ln(aluminum)), the serum aluminum level exhibited an independent and linear relationship with the CTR (β: 1.40, 95% confidence interval (CI), 0.6–2.2). A high serum aluminum level (≥6 ng/dL) was significantly associated with a CTR >0.5 in the crude analysis (odds ratio (OR): 2.15, 95% CI, 1.52–3.04) and remained significant after multivariable adjustment (OR: 2.45, 95% CI, 1.63–3.67). Moreover, the ln(aluminum) value was significantly associated with a CTR >0.5 (OR: 1.71, 95%CI, 1.28–2.29) in multivariable analysis, indicating a dose effect of aluminum on cardiomegaly. In conclusion, the serum aluminum level was independently associated with cardiac remodeling (elevated CTR) in patients on CHD.

Aluminum exposure at human dietary levels promotes vascular dysfunction and increases blood pressure in rats: A concerted action of NAD(P)H oxidase and COX-2

Aluminum (Al) is a non-essential metal and a significant environmental contaminant and is associated with a number of human diseases including cardiovascular disease. We investigated the effects of Al exposure at doses similar to human dietary levels on the cardiovascular system over a 60day period. Wistar male rats were divided into two major groups and received orally: 1) Low aluminum level - rats were subdivided and treated for 60days as follows: a) Untreated - ultrapure water; b) AlCl₃ at a dose of 8.3mg/kg bw for 60days, representing human Al exposure by diet; and 2) High aluminum level - rats were subdivided and treated for 42days as follows: C) Untreated - ultrapure water; d) AlCl₃ at 100mg/kg bw for 42days, representing a high level of human exposure to Al. Effects on systolic blood pressure (SBP) and vascular function of aortic and mesenteric resistance arteries (MRA) were studied. Endothelium and smooth muscle integrity were evaluated by concentration-response curves to acetylcholine (ACh) and sodium nitroprusside. Vasoconstrictor responses to phenylephrine (Phe) in the presence and absence of endothelium and in the presence of the NOS inhibitor L-NAME, the potassium channels blocker TEA, the NAD(P)H oxidase inhibitor apocynin, superoxide dismutase (SOD), the non-selective COX inhibitor indomethacin and the selective COX-2 inhibitor NS 398 were analyzed. Vascular reactive oxygen species (ROS), lipid peroxidation and total antioxidant capacity, were measured. The mRNA expressions of eNOS, NAD(P)H oxidase 1 and 2, SOD1, COX-2 and thromboxane A2 receptor (TXA-2 R) were also investigated. Al exposure at human dietary levels impaired the cardiovascular system and these effects were almost the same as Al exposure at much higher levels. Al increased SBP, decreased ACh-induced relaxation, increased response to Phe, decreased endothelial modulation of vasoconstrictor responses, the bioavailability of nitric oxide (NO), the involvement of potassium channels on vascular responses, as well as increased ROS production from NAD(P)H oxidase and contractile prostanoids mainly from COX-2 in both aorta and mesenteric arteries. Al exposure increased vascular ROS production and lipid peroxidation as well as altered the antioxidant status in aorta and MRA. Al decreased vascular eNOS and SOD1 mRNA levels and increased the NAD(P)H oxidase 1, COX-2 and TXA-2 R mRNA levels. Our results point to an excess of ROS mainly from NAD(P)H oxidase after Al exposure and the increased vascular prostanoids from COX-2 acting in concert to decrease NO bioavailability, thus inducing vascular dysfunction and increasing blood pressure. Therefore, 60-day chronic exposure to Al, which reflects common human dietary Al intake, appears to pose a risk for the cardiovascular system.

Mung bean (Phaseolus radiatus L.) polyphenol extract attenuates aluminum-induced cardiotoxicity through an ROS-triggered Ca2+/JNK/NF-κB signaling pathway in rats

Aluminum (Al) has been linked to the development of some cardiovascular diseases and mung bean is a functional food with the ability to detoxify. We aimed to evaluate the preventive effect and possible underlying mechanisms of the mung bean polyphenol extract (MPE) on Al-induced cardiotoxicity. Control, AlCl₃ (171.8 mg Al per kg body weight), MPE + AlCl₃ (Al-treatment plus 200 mg MPE per kg body weight), and a group of MPE per se were used. Al intake induced a significant increase of serum CK and LDH activity and the level of Na⁺, Ca²⁺, malondialdehyde and advanced oxidation protein products in the AlCl₃-treated rats' heart tissue. Administration of MPE significantly improved the integrity and normal ion levels of heart tissue, and attenuated oxidative damage and the accumulation of Al in Al-treated rats. MPE significantly inhibited Al-induced increase of myocardial p-JNK, cytoplasmic NF-κB, cytochrome C, and caspase-9 protein expressions. Therefore, these results showed that MPE has a cardiac protective effect against Al-induced biotoxicity through ROS-JNK and NF-κB-mediated caspase pathways. Furthermore, the stability constant for the vitexin-Al complex was analyzed (log K = log K₁ + log K₂ = 4.91 + 4.85 = 9.76). We found that MPE-mediated protection against Al-cardiotoxicity is connected both with MPE antioxidant and chelation properties.