Chromium in Health and Disease:

Adsorption of Chromate Ions by Layered Double Hydroxide-Bentonite Nanocomposite for Groundwater Remediation

Herein, magnesium/aluminum-layered double hydroxide (MgAl-LDH) and bentonite (BT) nanocomposites (LDH–BT) were prepared by co-precipitation (CP), exfoliation–reassembly (ER), and simple solid-phase hybridization (SP). The prepared LDH–BT nanocomposites were preliminarily characterized by using powder X-ray diffractometry, scanning electron microscopy, and zeta-potentiometry. The chromate adsorption efficacies of the pristine materials (LDH and bentonite) and the as-prepared nanocomposites were investigated. Among the composites, the LDH–BT_SP was found to exhibit the highest chromate removal efficiency of 65.7%. The effect of varying the LDH amount in the LDH–BT composite was further investigated, and a positive relationship between the LDH ratio and chromate removal efficiency was identified. The chromate adsorption by the LDH–BT_SP was performed under various concentrations (isotherm) and contact times (kinetic). The results of the isotherm experiments were well fitted with the Langmuir and Freundlich isotherm model and demonstrate multilayer chromate adsorption by the heterogeneous LDH–BT_SP, with a homogenous distribution of LDH nanoparticles. The mobility of the as-prepared LDH–BT_SP was investigated on a silica sand-filled column to demonstrate that the mobility of the bentonite is dramatically decreased after hybridization with LDH. Furthermore, when the LDH–BT_SP was injected into a box container filled with silica sand to simulate subsurface soil conditions, the chromate removal efficacy was around 43% in 170 min. Thus, it was confirmed that the LDH–BT prepared by solid-phase hybridization is a practical clay-based nanocomposite for in situ soil and groundwater remediation.

Heavy Metal Accumulation in Rice and Aquatic Plants Used as Human Food: A General Review

Aquatic ecosystems are contaminated with heavy metals by natural and anthropogenic sources. Whilst some heavy metals are necessary for plants as micronutrients, others can be toxic to plants and humans even in trace concentrations. Among heavy metals, cadmium (Cd), arsenic (As), chromium (Cr), lead (Pb), and mercury (Hg) cause significant damage to aquatic ecosystems and can invariably affect human health. Rice, a staple diet of many nations, and other aquatic plants used as vegetables in many countries, can bioaccumulate heavy metals when they grow in contaminated aquatic environments. These metals can enter the human body through food chains, and the presence of heavy metals in food can lead to numerous human health consequences. Heavy metals in aquatic plants can affect plant physicochemical functions, growth, and crop yield. Various mitigation strategies are being continuously explored to avoid heavy metals entering aquatic ecosystems. Understanding the levels of heavy metals in rice and aquatic plants grown for food in contaminated aquatic environments is important. Further, it is imperative to adopt sustainable management approaches and mitigation mechanisms. Although narrowly focused reviews exist, this article provides novel information for improving our understanding about heavy metal accumulation in rice and aquatic plants, addressing the gaps in literature.

Effect of chromium supplementation on hs-CRP, TNF-α and IL-6 as risk factor for cardiovascular diseases: A meta-analysis of randomized-controlled trials

BACKGROUND

The objective of this systematic review is to assess the relationship between chromium supplementation and inflammatory biomarkers levels (hs-CRP, TNF-α, IL-6) as risk factor for cardiovascular diseases. Recent studies raise questions regarding the potential of chromium supplementation to decrease the blood-levels of inflammatory markers, lowering cellular oxidative stress as markers of myocardial infarction; however, the results of the researches are inconclusive.

METHODS

The following databases including PubMed, Scopus, Cochran Library and Embase databases were systematically searched until April 2020. Analysis was performed using random-effect model.

RESULTS

The pooled findings for biomarkers of inflammation showed that chromium supplementation significantly reduced serum high-sensitivity C-reactive protein (hs-CRP) (WMD: -0.87 mg/dL, 95% CI: -1.49, -0.26), and tumor necrosis factor-alpha (TNF-α) (WMD: -0.97 pg/ml; 95% CI: -1.92, -0.01) and chromium insignificantly reduced interleukin -6 (IL-6) (WMD: -0.45 pg/ml, 95% CI: -1.18, 0.29).

CONCLUSION

Overall, the results of this systematic review and meta-analysis imply that chromium supplementation may help to improve biomarkers of inflammation as markers of myocardial infarction.