Review

Authors: Wolfgang Maret

After 40 years of significant work, it was generally accepted that chromium in its trivalent valence state, Cr(III), is an essential micronutrient for humans. This view began to be challenged around the turn of the millennium. Some investigators argue that its effects on glucose and lipid metabolism reflect a pharmacological rather than a nutritional mode of action while yet others express concern about the toxicity and safety of supplemental chromium. Understanding the conjectures requires a reflection on the different definitions of "essential" and a perspective on the development of the field, which in itself is a remarkable snippet of science history and education. At the center of the discussion is our failure to have established a molecular structure and a specific site of action of a biological chromium complex. Instead, many different types of Cr(III) complexes, in particular chromium picolinate, but also those with nicotinate, propionate, histidinate, chloride, and other ligands, all with different chemical properties and biological activities, are being used in laboratory investigations and supplementation. Without knowledge of the metabolic transformations and the specific chemical properties that biological ligands impart on chromium, many of these investigations, in particular those ex vivo, have limited value for understanding chromium's biological function. Whether a chromium deficiency exists in humans and who is affected is poorly defined. There is evidence for the efficacy of chromium supplements in improving conditions in metabolic syndrome and in some diabetes Type 2 patients, but there are no effects on body composition in healthy individuals. Chromium is present in human tissues and in our food and Cr(III) compounds are given in (total) parenteral nutrition, taken as a supplement by athletes and bodybuilders, are ingredients of vitamin pills consumed by the general population, and are employed in animal nutrition. Another contentious issue is whether Cr(III) complexes are safe, as chromium in its hexavalent state, Cr(VI) (chromate), is genotoxic and a group I carcinogen for humans with sufficient evidence for inhalation and lung cancer. For the benefit of human health, there is a continuing need for a balanced view and informed and robust experiments to determine the specific biological molecules that are involved in the metabolism of Cr(III), the activity of biological Cr(III) complexes at specific sites of action, and the amount of supplemental Cr(III) that potentially causes long-term toxicity.

Topics: Animals; Chromium; Diabetes Mellitus; Dietary Supplements; Humans; Metabolic Syndrome

PubMed: 30855110
DOI: 10.1515/9783110527872-015

Authors: John B Vincent, Henry C Lukaski

Two oxidation states of chromium are considered to be biologically and environmentally relevant based on their stability in the presence of water and oxygen. Compounds containing chromium(6 + ) are mutagenic and carcinogenic when inhaled and potentially when ingested orally in large quantity as well. Chromium as the trivalent will be the focus of this work as it was proposed to be an essential element for mammals ∼60 y ago; however, in the last 2 decades its status has been questioned. Chromium has been postulated to be involved in regulating carbohydrate and lipid (and potentially also protein) metabolism by enhancing insulin's efficacy (1). However, in 2014, the European Food Safety Authority found no convincing evidence that chromium is an essential element (2). Dietary chromium apparently is absorbed via passive diffusion and the extent of absorption is low (∼1%). Chromium is maintained in the bloodstream bound to the protein transferrin. It is generally believed to be delivered to tissues by transferrin via endocytosis (1). No unambiguous animal model of chromium deficiency has been established (2). One limitation in characterizing chromium deficiency in humans is the lack of an accepted biomarker of chromium nutritional status. Attempts to identify a glucose tolerance factor have not provided a chemically defined functional compound that conforms with the proposed physiologic role of chromium as a facilitator of insulin action in vivo.

Topics: Animals; Carbohydrate Metabolism; Chromium; Diet; Endocytosis; Humans; Insulin; Lipid Metabolism; Nutritional Status; Recommended Dietary Allowances; Transferrin

PubMed: 30032219
DOI: 10.1093/advances/nmx021

Review

Authors: Sandra S Wise, John Pierce Wise

Many metals serve as micronutrients which protect against genomic instability. Chromium is most abundant in its trivalent and hexavalent forms. Trivalent chromium has historically been considered an essential element, though recent data indicate that while it can have pharmacological effects and value, it is not essential. There is no data indicating that trivalent chromium promotes genomic stability and, instead may promote genomic instability. Hexavalent chromium is widely accepted as highly toxic and carcinogenic with no nutritional value. Recent data indicate that it causes genomic instability and also has no role in promoting genomic stability.

Topics: Carcinogens; Chromium; Genomic Instability; Humans; Nutritive Value

PubMed: 22192535
DOI: 10.1016/j.mrfmmm.2011.12.002

Review

Authors: Ying Li, Yi Huang, Zijing Li...

Chromium (Cr) is a toxic heavy metal that gives rise to environmental pollution and human risk. Chromium stable isotopes have a wide range of applications in both environmental field and earth science field. In this contribution, we focus on the application of the Cr isotope in both tracing pollution sources and monitoring Cr(Ⅵ) pollution. Meanwhile, we also provide a description of the main influencing factors controlling Cr isotope fractionation, chromium isotope analytical methods, and terrestrial Cr release. Chromium isotope tracing of contaminant sources is a new application method, it has a tremendous advantage in searching for the source of Cr pollution, which has not been covered in previous reviews. At the end of the article, the current status of Cr isotope applications in the paleo-environment is explained. Although there are still some uncertainties in practical applications, chromium isotope system shows great promise in the environmental aspects.

Topics: Chemical Fractionation; Chromium; Chromium Isotopes; Humans; Oxidation-Reduction

PubMed: 35999763
DOI: 10.1016/j.ecoenv.2022.113948

Review

Authors: Minmin Zou, Ming Dong, Tian Zhao...

MIL-101(Cr) is one of the most well-studied chromium-based metal-organic frameworks, which consists of metal chromium ion and terephthalic acid ligand. It has an ultra-high specific surface area, large pore size, good thermal/chemical/water stability, and contains unsaturated Lewis acid sites in its structure. Due to the physicochemical properties and structural characteristics, MIL-101(Cr) has a wide range of applications in aqueous phase adsorption, gas storage and separation, and catalysis. In this review, the latest synthesis of MIL-101(Cr) and its research progress in adsorption and catalysis are reviewed.

Topics: Adsorption; Chromium; Metal-Organic Frameworks; Water Pollutants, Chemical

PubMed: 36012661
DOI: 10.3390/ijms23169396

Review

Authors: Meesala Krishna Murthy, Pratima Khandayataray, Samprit Padhiary...

Living beings have been devastated by environmental pollution, which has reached its peak. The disastrous pollution of the environment is in large part due to industrial wastes containing toxic pollutants. The widespread use of chromium (Cr (III)/Cr (VI)) in industries, especially tanneries, makes it one of the most dangerous environmental pollutants. Chromium pollution is widespread due to ineffective treatment methods. Bioremediation of chromium (Cr) using bacteria is very thoughtful due to its eco-friendly and cost-effective outcome. In order to counter chromium toxicity, bacteria have numerous mechanisms, such as the ability to absorb, reduce, efflux, or accumulate the metal. In this review article, we focused on chromium toxicity on human and environmental health as well as its bioremediation mechanism.

Topics: Humans; Biodegradation, Environmental; Chromium; Environmental Pollutants; Industrial Waste; Industry; Bacteria

PubMed: 35537040
DOI: 10.1515/reveh-2021-0139

Authors: J Barbosa

Topics: Animals; Carbohydrate Metabolism; Chromium; Diabetes Mellitus; Humans; Rats

PubMed: 884474
DOI: 10.1136/bmj.2.6081.266

Authors: Edyta Boros-Lajszner, Jadwiga Wyszkowska, Jan Kucharski...

Chromium (Cr) can exist in several oxidation states, but the two most stable forms-Cr(III) and Cr(VI)-have completely different biochemical characteristics. The aim of the present study was to evaluate how soil contamination with Cr(III) and Cr(VI) in the presence of NaEDTA affects L. biomass; assess the remediation capacity of L. based on its tolerance index, translocation factor, and chromium accumulation; and investigate how these chromium species affect the soil enzyme activity and physicochemical properties of soil. This study consisted of a pot experiment divided into two groups: non-amended and amended with NaEDTA. The Cr(III)- and Cr(VI)-contaminated soil samples were prepared in doses of 0, 5, 10, 20, and 40 mg Cr kg d.m. soil. The negative effect of chromium manifested as a decreased biomass of L. (aboveground parts and roots). Cr(VI) proved to be more toxic than Cr(III). The tolerance indices (TI) showed that L. tolerates Cr(III) contamination better than Cr(VI) contamination. The translocation values for Cr(III) were much lower than for Cr(VI). L. proved to be of little use for the phytoextraction of chromium from soil. Dehydrogenases were the enzymes which were the most sensitive to soil contamination with Cr(III) and Cr(VI). Conversely, the catalase level was observed to be the least sensitive. NaEDTA exacerbated the negative effects of Cr(III) and Cr(VI) on the growth and development of L. and soil enzyme activity.

Topics: Avena; Soil; Edetic Acid; Soil Pollutants; Chromium

PubMed: 37375248
DOI: 10.3390/molecules28124693

Review

Authors: Pooja Sharma, Surendra Pratap Singh, Sheetal Kishor Parakh...

Industrial effluents/wastewater are the main sources of hexavalent chromium (Cr (VI)) pollutants in the environment. Cr (VI) pollution has become one of the world's most serious environmental concerns due to its long persistence in the environment and highly deadly nature in living organisms. To its widespread use in industries Cr (VI) is highly toxic and one of the most common environmental contaminants. Cr (VI) is frequently non-biodegradable in nature, which means it stays in the environment for a long time, pollutes the soil and water, and poses substantial health risks to humans and wildlife. In living things, the hexavalent form of Cr is carcinogenic, genotoxic, and mutagenic. Physico-chemical techniques currently used for Cr (VI) removal are not environmentally friendly and use a large number of chemicals. Microbes have many natural or acquired mechanisms to combat chromium toxicity, such as biosorption, reduction, subsequent efflux, or bioaccumulation. This review focuses on microbial responses to chromium toxicity and the potential for their use in environmental remediation. Moreover, the research problem and prospects for the future are discussed in order to fill these gaps and overcome the problem associated with bacterial bioremediation's real-time applicability.

Topics: Biodegradation, Environmental; Chromium; Environmental Pollutants; Humans; Soil; Wastewater; Water Pollutants, Chemical

PubMed: 35164635
DOI: 10.1080/21655979.2022.2037273

Review

Authors: Obulisamy Parthiba Karthikeyan, Thomas J Smith, Shamsudeen Umar Dandare...

Manufacturing and resource industries are the key drivers for economic growth with a huge environmental cost (e.g. discharge of industrial effluents and post-mining substrates). Pollutants from waste streams, either organic or inorganic (e.g. heavy metals), are prone to interact with their physical environment that not only affects the ecosystem health but also the livelihood of local communities. Unlike organic pollutants, heavy metals or trace metals (e.g. chromium, mercury) are non-biodegradable, bioaccumulate through food-web interactions and are likely to have a long-term impact on ecosystem health. Microorganisms provide varied ecosystem services including climate regulation, purification of groundwater, rehabilitation of contaminated sites by detoxifying pollutants. Recent studies have highlighted the potential of methanotrophs, a group of bacteria that can use methane as a sole carbon and energy source, to transform toxic metal (loids) such as chromium, mercury and selenium. In this review, we synthesise recent advances in the role of essential metals (e.g. copper) for methanotroph activity, uptake mechanisms alongside their potential to transform toxic heavy metal (loids). Case studies are presented on chromium, selenium and mercury pollution from the tanneries, coal burning and artisanal gold mining, respectively, which are particular problems in the developing economy that we propose may be suitable for remediation by methanotrophs. Video Abstract.

Topics: Chromium; Ecosystem; Environmental Pollution; Mercury; Metals, Heavy

PubMed: 34229757
DOI: 10.1186/s40168-021-01112-y