Cadmium, environmental exposure, and health outcomes
01 May 2011-Ciencia & Saude Coletiva (ABRASCO - Associação Brasileira de Saúde Coletiva)-Vol. 16, Iss: 5, pp 2587-2602
TL;DR: Concerns are raised about the validity of the current safe intake level that uses the kidney as the sole target in assessing the health risk from ingested cadmium, and the default 5% absorption rate in the threshold-type risk assessment model is questioned.
Abstract: We provide an update of the issues surrounding health risk assessment of exposure to cadmium in food. Bioavailability of ingested cadmium has been confirmed in studies of persons with elevated dietary exposure, and the findings have been strengthened by the substantial amounts of cadmium accumulated in kidneys, eyes, and other tissues and organs of environmentally exposed individuals. We hypothesized that such accumulation results from the efficient absorption and systemic transport of cadmium, employing multiple transporters that are used for the body's acquisition of calcium, iron, zinc, and manganese. Adverse effects of cadmium on kidney and bone have been observed in environmentally exposed populations at frequencies higher than those predicted from models of exposure. Population data raise concerns about the validity of the current safe intake level that uses the kidney as the sole target in assessing the health risk from ingested cadmium. The data also question the validity of incorporating the default 5% absorption rate in the threshold-type risk assessment model, known as the provisional tolerable weekly intake (PTWI), to derive a safe intake level for cadmium.
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TL;DR: This review gives details about some heavy metals and their toxicity mechanisms, along with their health effects.
Abstract: Heavy metal toxicity has proven to be a major threat and there are several health risks associated with it. The toxic effects of these metals, even though they do not have any biological role, remain present in some or the other form harmful for the human body and its proper functioning. They sometimes act as a pseudo element of the body while at certain times they may even interfere with metabolic processes. Few metals, such as aluminium, can be removed through elimination activities, while some metals get accumulated in the body and food chain, exhibiting a chronic nature. Various public health measures have been undertaken to control, prevent and treat metal toxicity occurring at various levels, such as occupational exposure, accidents and environmental factors. Metal toxicity depends upon the absorbed dose, the route of exposure and duration of exposure, i.e. acute or chronic. This can lead to various disorders and can also result in excessive damage due to oxidative stress induced by free radical formation. This review gives details about some heavy metals and their toxicity mechanisms, along with their health effects.
3,580 citations
TL;DR: Recent studies show that cadmium induces various epigenetic changes in mammalian cells, both in vivo and in vitro, causing pathogenic risks and the development of various types of cancers.
Abstract: Cadmium (Cd) is a toxic non-essential transition metal that poses a health risk for both humans and animals. It is naturally occurring in the environment as a pollutant that is derived from agricultural and industrial sources. Exposure to cadmium primarily occurs through the ingestion of contaminated food and water and, to a significant extent, through inhalation and cigarette smoking. Cadmium accumulates in plants and animals with a long half-life of about 25–30 years. Epidemiological data suggest that occupational and environmental cadmium exposure may be related to various types of cancer, including breast, lung, prostate, nasopharynx, pancreas, and kidney cancers. It has been also demonstrated that environmental cadmium may be a risk factor for osteoporosis. The liver and kidneys are extremely sensitive to cadmium’s toxic effects. This may be due to the ability of these tissues to synthesize metallothioneins (MT), which are Cd-inducible proteins that protect the cell by tightly binding the toxic cadmium ions. The oxidative stress induced by this xenobiotic may be one of the mechanisms responsible for several liver and kidney diseases. Mitochondria damage is highly plausible given that these organelles play a crucial role in the formation of ROS (reactive oxygen species) and are known to be among the key intracellular targets for cadmium. When mitochondria become dysfunctional after exposure to Cd, they produce less energy (ATP) and more ROS. Recent studies show that cadmium induces various epigenetic changes in mammalian cells, both in vivo and in vitro, causing pathogenic risks and the development of various types of cancers. The epigenetics present themselves as chemical modifications of DNA and histones that alter the chromatin without changing the sequence of the DNA nucleotide. DNA methyltransferase, histone acetyltransferase, histone deacetylase and histone methyltransferase, and micro RNA are involved in the epigenetic changes. Recently, investigations of the capability of sunflower (Helianthus annuus L.), Indian mustard (Brassica juncea), and river red gum (Eucalyptus camaldulensis) to remove cadmium from polluted soil and water have been carried out. Moreover, nanoparticles of TiO2 and Al2O3 have been used to efficiently remove cadmium from wastewater and soil. Finally, microbial fermentation has been studied as a promising method for removing cadmium from food. This review provides an update on the effects of Cd exposure on human health, focusing on the cellular and molecular alterations involved.
812 citations
Liverpool School of Tropical Medicine1, University of Liverpool2, Queen Mary University of London3, Harvard University4, University of Oxford5, University of Birmingham6, Columbia University7, Sri Ramachandra University8, University of California, Berkeley9, University of California, San Francisco10, Malawi-Liverpool-Wellcome Trust Clinical Research Programme11, Johns Hopkins University12, Oregon Health & Science University13, Fudan University14, Health Effects Institute15, University of Georgia16, University of Aberdeen17, Ohio State University18
TL;DR: Evidence for the association between household air pollution and respiratory infections, respiratory tract cancers, and chronic lung diseases is reviewed, as well as study design issues and potential effective interventions to prevent these disease burdens.
672 citations
TL;DR: AtABCC1 and AtABCC2 are important vacuolar transporters that confer tolerance to cadmium and mercury, in addition to their role in arsenic detoxification, which provide useful tools for genetic engineering of plants with enhanced metal tolerance and accumulation, which are desirable characteristics for phytoremediation.
Abstract: Heavy metals such as cadmium (Cd) and mercury (Hg) are toxic pollutants that are detrimental to living organisms. Plants employ a two-step mechanism to detoxify toxic ions. First, phytochelatins bind to the toxic ion, and then the metal-phytochelatin complex is sequestered in the vacuole. Two ABCC-type transporters, AtABCC1 and AtABCC2, that play a key role in arsenic detoxification, have recently been identified in Arabidopsis thaliana. However, it is unclear whether these transporters are also implicated in phytochelatin-dependent detoxification of other heavy metals such as Cd(II) and Hg(II). Here, we show that atabcc1 single or atabcc1 atabcc2 double knockout mutants exhibit a hypersensitive phenotype in the presence of Cd(II) and Hg(II). Microscopic analysis using a Cd-sensitive probe revealed that Cd is mostly located in the cytosol of protoplasts of the double mutant, whereas it occurs mainly in the vacuole of wild-type cells. This suggests that the two ABCC transporters are important for vacuolar sequestration of Cd. Heterologous expression of the transporters in Saccharomyces cerevisiae confirmed their role in heavy metal tolerance. Over-expression of AtABCC1 in Arabidopsis resulted in enhanced Cd(II) tolerance and accumulation. Together, these results demonstrate that AtABCC1 and AtABCC2 are important vacuolar transporters that confer tolerance to cadmium and mercury, in addition to their role in arsenic detoxification. These transporters provide useful tools for genetic engineering of plants with enhanced metal tolerance and accumulation, which are desirable characteristics for phytoremediation.
456 citations
Cites background from "Cadmium, environmental exposure, an..."
...Cadmium can cause human diseases, including kidney disorders, neurotoxicity and osteoporosis (Jarup and Akesson, 2009; Satarug et al., 2010)....
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TL;DR: This review focuses on the effects of heavy metal wastes generated from gold mining activities on the environment and the various mechanisms used by bacteria to counteract the effect of these heavy metals in their immediate environment.
Abstract: Mining activities can lead to the generation of large quantities of heavy metal laden wastes which are released in an uncontrolled manner, causing widespread contamination of the ecosystem Though some heavy metals classified as essential are important for normal life physiological processes, higher concentrations above stipulated levels have deleterious effects on human health and biota Bacteria able to withstand high concentrations of these heavy metals are found in the environment as a result of various inherent biochemical, physiological, and/or genetic mechanisms These mechanisms can serve as potential tools for bioremediation of heavy metal polluted sites This review focuses on the effects of heavy metal wastes generated from gold mining activities on the environment and the various mechanisms used by bacteria to counteract the effect of these heavy metals in their immediate environment
435 citations
References
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3,514 citations
TL;DR: It can be anticipated that a considerable proportion of the non-smoking adult population has urinary cadmium concentrations of 0.5 microg/g creatinine or higher in non-exposed areas, and for smokers this proportion is considerably higher, which implies no margin of safety between the point of departure and the exposure levels in the general population.
1,954 citations
TL;DR: This review discusses the molecular mechanisms of toxic metal accumulation in plants and algae, the responses to metal exposure, as well as the understanding of metal tolerance and its evolution.
1,598 citations
"Cadmium, environmental exposure, an..." refers background in this paper
...Cadmium is a contaminant in most human foodstuffs because of its high rates of soil-to-plant transfer, rendering diet a primary source of exposure among non-smoking, non-occupationally exposed populations (Clemens 2006; Franz et al. 2008; McLaughlin et al. 2006)....
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...Such mechanisms are crucial for metals since they cannot be synthesized nor destroyed by the cells and must be “mined” from the external environment (Clemens 2006)....
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TL;DR: In this paper, levels of cadmium found in major food groups are highlighted together with levels found in liver and kidney samples from non-occupationally exposed populations, suggesting that renal toxicity may be an early warning of complications, sub-clinical or clinical morbidity.
961 citations
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