Our readership spans scientists, professors, researchers, librarians, and students, as well as business professionals. Eight common heavy metals are discussed in this brief: arsenic, barium, cadmium, chromium, lead, mercury, selenium, and sil- ver. Heavy metal and human health 1. Humans may directly get in contact with heavy metals by consuming contaminated food stuffs, sea animals, and drinking of water, through inhalation of polluted air as dust fumes, or through occupational exposure at workplace . Exposure to chromium compounds can result in the formation of ulcers such as nasal septum ulcer which are very common in chromate workers. In this study, lead, copper and nickel were the selected heavy metal. Vegetable samples were collected at the São Paulo General Warehousing and Centers Company, and the heavy metal content was determined by atomic absorption spectrophotometry. Inactivation of p53 allows uncontrolled cell division and thus p53 gene disruption has been associated with most human cancers. Elemental and methylmercury are toxic to the central and peripheral nervous systems. Thus, heavy metals may induce carcinogenic effect by targeting a number of these proteins. Cadmium is also classified as group 1 carcinogens for humans by the International Agency for Research on Cancer. It was also observed that when protein misfolded in the presence of heavy metals, the misfolded protein could not be rescued in the presence of reduced glutathione or EDTA chelator. Summarized in Figure 4 is the various mechanisms of heavy metal intoxication. Lead can disrupt neurotransmission by inhibiting the neuronal voltage-gated calcium (Ca2+) channels (VGCCs) . Thus, protein damaged are usually metal-catalyzed and involves oxidative scission, bityrosine cross links, loss of histidine residues, the introduction of carbonyl groups, and the formation of protein-centered alkyl (R•), alkoxyl (RO•) and alkylperoxyl (ROO•) radicals . Reduction of Ca2+ entry into the cell will prevent neurotransmitter release and thus impair signalization leading to neurological disease states [62, 63]. This research aims at reviewing the presence of heavy metals in drinking water and their possible health effects. The various sources of heavy metals are summarized in Figure 1. However, the main differences between manganism and Parkinson disease is the insensitivity of manganism to levodopa (l-DOPA) administration and also the differences in the symptoms and progression of the disease . These are all naturally occurring substances which are often present in … growth due to phytotoxicity, and environmental health of soil organisms. Even though there are no immediate problems, heavy metals keep on accumulating in our body. Tajchman K, Ukalska-Jaruga A, Bogdaszewski M, Pecio M, Dziki-Michalska K. Animals (Basel). This chapter will highlight on the various sources of heavy metals and the processes that promote their exposure and bioaccumulation in the human body. Humans get in contact with arsenic through several means which include industrial sources such as smelting and microelectronic industries. Heavy metals are pretty much everywhere you turn. Some of these heavy metals such as copper, cobalt, iron, nickel, magnesium, molybdenum, chromium, selenium, manganese and zinc have functional roles which are essential for various diverse physiological and biochemical activities in the body. Lead poisoning is mostly related to the gastrointestinal tract and central nervous system in children and adults . Cadmium initially binds to blood cells and albumin, and subsequently binds to metallothionein in kidney and liver tissue. This is because the toxicity level of a metal depends on factors such as the organisms which are exposed to it, its nature, its biological role and the period at which the organisms are exposed to the metal. Toxicity of heavy metals depends on a lot of factors such as which metal is present, the nature of the metal, the biological role of the metal, the organism exposed and the period of the organisms life when it is exposed. Nickel has been shown to be implicated in regulating the expression of specific long non-coding RNAs, certain mRNAs and microRNAs. In the above reaction, the oxidized heavy metal replaces the hydrogen of the SH group and the methyl of the SCH3 group thereby inhibiting the function of the protein or activity of the enzyme. Godwill Azeh Engwa, Paschaline Udoka Ferdinand, Friday Nweke Nwalo and Marian N. Unachukwu (June 19th 2019). Heavy metals have been used by humans … Arsenic has also been shown to generate free radicals such as superoxide (O2•–), singlet oxygen (1O2), nitric oxide (NO•), hydrogen peroxide (H2O2), the peroxyl radical (ROO•) , dimethylarsinic peroxyl radicals ((CH3)2AsOO•) and also the dimethylarsinic radical ((CH3)2As•)  in some studies though the mechanism for the generation of all these reactive species remains unclear. 2020 Mar;30(3):167-176. doi: 10.1080/15376516.2019.1701594. 2020 Dec 9;17(24):9218. doi: 10.3390/ijerph17249218. The term “heavy metals” is sometimes used to suggest pollution and toxic effects; 2 it implies metals of high density, but has also been used for other metals. Help us write another book on this subject and reach those readers. Organic mercury is lipophilic in nature and thus can easily penetrate cell membranes. Also, long term accumulation of heavy metals in the body may result in slowing the progression of physical, muscular and neurological degenerative processes that mimic certain diseases such as Parkinson’s disease and Alzheimer’s disease . Even low concentration of heavy metals may inhibit the physiological metabolism of plant. Exposure to elevated levels of lead can cause the plasma membrane of the blood brain barrier to move into the interstitial spaces leading to edema . It is now suggested that inhibition of either NMDARs or VGCCs by lead would result in a significant decrease of Ca2+ influx into the cell. Mercury is an element that can easily combine with other elements to form inorganic and organic mercury. The various health effects of some heavy metals will be highlighted below. But, heavy metals are the most damaging chemicals in water. Increased cadmium toxicity in this population was found to be associated with increased risk of bone fractures in women, as well as decreased bone density and height loss in males and females. Most of the other heavy metals are generally toxic to the body at very low level. It is still a common practice in India to cover sweetmeats by a silver or golden foil. It has been observed that “Itai-itai” disease, an epidemic of bone fractures in Japan is due to cadmium contamination . Saccharomyces cerevisiae (budding yeast) cells was shown to accumulate aggregated proteins after it was exposed to equi-toxic concentrations of cadmium, arsenite and chromium (Cr(VI)) and the effect of protein aggregation was influenced by heavy metals in this order: arsenic > cadmium > chromium . This has been shown in animal studies were manganese exposure has led to specific deficits in the dopaminergic system . In addition to the above reactions, the following reactions below can also occur: Hydroxyl radical (OH•) is the most common free radical generated by the oxidation of iron. Among the heavy metals, As, Cd and Pb have extensively been studied for their public health effects [2,8]. Keywords: Bioavailability, Contamination, Heavy metals, Human health… BDNF activity is also dependent on Ca2+ and thus has been implicated in the development of neurological diseases. 2000 Owerri, Imo State, Nigeria. A recent IUPAC Technical Report (Duffus, 2002) discusses the inappropriateness of this term and the term is avoided. The OH• radical formed is capable of reacting with several biomolecules. Although lead poisoning is preventable, it still remains a dangerous disease as it can affect most of the organs of the body. This was first observed when heavy metals such as cadmium, lead, mercury and arsenite were shown to effectively interfere with the refolding of chemically denatured proteins . Iron is a useful heavy metal in the human body as it is a constituent of certain biological molecules like the hemoglobin and involved in various physiological activities. Alongside these mechanisms, the noxious health effects of these heavy metals are discussed. This is a heavy metal which is used in industries to produce copper pipes, cables, wires, copper cookware, etc. However, there are no studies so far that have been able to show any associations between amalgam fillings and ill health. Hence, there is a need for proper understanding of mechanism involved, such as the concentrations and oxidation states, which make them harmful. Also, occupational exposure to mercury as observed by researchers has been associated with measurable declines in performance on neurobehavioral tests of motor speed, visual scanning, visuomotor coordination, verbal and visual memory. Iron toxicity occurs in four stages. Furthermore, manganese can oxidize dopamine (DA) to react with quinone species thereby disrupting the dopaminergic system (for review, see ). Determination of toxic elements (mercury, cadmium, lead, tin and arsenic) in fish and shellfish samples. Manganism is a neurological disease due to manganese characterized by rigidity, action tremour, a mask-like expression, gait disturbances, bradykinesia, micrographia, memory and cognitive dysfunction, and mood disorder . Heavy metals are toxic to soil, plants, aquatic life and human health if their concentration is high in the compost. Lead toxicity is targeted towards the memory and learning processes of the brain and can be mediated through three processes. The in vivo potency of these agents to trigger protein aggregation probably depends on the efficiency of their cellular uptake/export and on their distinct modes of biological action. ver, lung, kidney or bladder in 13 per 1000 persons. The influence of these heavy metals on plants and their metabolic activities caused by the geological and biological redistribution of heavy metals through pollution of the air, water and soil were briefly discussed in this article. The results showed that the residents in the e-waste recycling sites are facing a potential higher daily intake of heavy metals. Heavy metal may cause proteins to aggregate as arsenite-induced protein aggregation was observed and shown to be concentration-dependent. These include substances such as DMSA, DMPS, and EDTA. The p53 protein is an important protein in cell division as it guards a cell-cycle checkpoint and control cell division . Long-term exposure can lead to the formation of skin lesions, pulmonary disease, neurological problems, peripheral vascular disease, diabetes mellitus, hypertension and cardiovascular disease . We are a community of more than 103,000 authors and editors from 3,291 institutions spanning 160 countries, including Nobel Prize winners and some of the world’s most-cited researchers. Toxicity due to lead exposure is called lead poisoning. The mechanism of free radical generation is specific to the type of heavy metal. Cadmium displaces zinc and calcium ions from zinc finger proteins and metalloproteins [76, 77]. Some health-care practitioners recommend the use of pharmaceutical methods, including substances that bind to – or chelate – the heavy metal and hasten its removal from the body. Additionally, metal-dependent damage to multiple organ systems can occur with primary targets being the kidneys, liver, brain and other rapidly dividing cells. The order of heavy metal in terms of their efficacy in folding inhibition is mercury > cadmium > lead and correlates with the relative stability of their monodentate complexes with imidazole, thiol and carboxylate groups in proteins . Lead targets multiple organs in the body due to its systemic toxicity which can cause Available from: Sources of heavy metal exposure to humans, Route of exposure, bio-uptake and bioaccumulation of heavy metals in humans, Health effects of heavy metal toxicity in humans, Biochemistry, Department of Chemical Sciences, Godfrey Okoye University, Nigeria, Department of Environmental Biotechnology, Bio-resource Development Centre, National Biotechnology and Development Agency (NABDA), Nigeria, Department of Biotechnology, Federal University, Ndufu-Alike Ikwo (FUNAI), Nigeria, Department of Biological Sciences, Godfrey Okoye University, Nigeria. Vegetables are considered to be an important component of human diet as they are rich sources of vitamins, minerals and fibers. All sampled vegetables presented average concentrations of Cd and Ni lower than the permissible limits … The main sources of lead exposure include drinking water, food, cigarette, industrial processes and domestic sources. Heavy metals may be transported through erosion, run-off or acid rain to different locations on soils and water bodies. NIH Heavy metals can damage and alter the functioning of organs such as the brain, kidney, lungs, liver, and blood. The heavy metals at exceedingly higher concentrations than the required physiological demand of vegetables can cause lethal effect in them as well as human health through food chain [4, 20]. Exposure to elevated levels of metallic, inorganic and organic mercury can damage the kidney, brain and developing fetus  while methyl mercury is highly carcinogenic. Heavy metal toxicity has proved to be a major threat as several health risks are associated with it.  reported that drinking 1 L/day water with As of 50 µg/L over one’s life time could lead to cancer of the li. These metals have been extensively studied and their effects on human health regularly reviewed by international bodies such as the WHO. Several signaling proteins or cellular regulatory proteins that participate in apoptosis, cell cycle regulation, DNA repair, DNA methylation, cell growth and differentiation are targets of heavy metals . The general population is primarily exposed to mercury via food, fish being a major source of methyl mercury exposure, and dental amalgam. In vitro studies have shown arsenic to alter the expression of p53 protein which also led to decreased expression of p21, one downstream target . 2021 Jan 6. doi: 10.1007/s12011-020-02541-w. Online ahead of print. Cadmium is highly toxic to the kidney and it accumulates in the proximal tubular cells in higher concentrations. This metal is mostly used in industries for the production of paints, pigments alloys, coatings, batteries as well as plastics. Epub 2017 Aug 2. National Center for Biotechnology Information, Unable to load your collection due to an error, Unable to load your delegates due to an error. Food chain polluted with toxic metals and metalloids is a significant path of human exposure and thus may cause a number of hazardous effects on human health. ppm, parts per million; mg, milligram; EPA, Environmental Protection Agency; OSHA, Occupational Safety and Health Administration; FDA, Food and Drug Administration. Acute exposure of lead can cause headache, loss of appetite, abdominal pain, fatigue, sleeplessness, hallucinations, vertigo, renal dysfunction, hypertension and arthritis while chronic exposure can result in birth defects, mental retardation, autism, psychosis, allergies, paralysis, weight loss, dyslexia, hyperactivity, muscular weakness, kidney damage, brain damage, coma and may even cause death . Other forms of mercury contamination in humans may be through anthropogenic activities such as municipal wastewater discharges, agriculture, incineration, mining, and discharges of industrial wastewater . Heavy metals concentrations were determined in the samples using atomic … The Effects of Toxic Metals. Cadmium is emitted through industrial processes and from cadmium smelters into sewage sludge, fertilizers, and groundwater which can remain in soils and sediments for several decades and taken up by plants. 2015).Vegetables provide the human body with essential trace elements which are necessary for healthy life. Little is known on the potential of mercury to act as a mutagen or carcinogen. 81 possible environmental impact of the local metallurgical industry, and to investigate the effect of 82 heavy metal contamination on human health in the Wumeng mountain area of China. These metals have been extensively studied and their effects on human health regularly reviewed by international bodies such as the WHO. To date our community has made over 100 million downloads. Vegetables constitute the most important daily diets in many of the households globally [ 21 , 22 ]. Mercury and its compound affects the nervous system and thus increased exposure of mercury can alter brain functions and lead to tremors, shyness, irritability, memory problems and changes in hearing or vision. Nevertheless, cancer is a leading cause of morbidity, mortality, and premature death worldwide. The impact of the heavy metals on aquatic organisms is due to the movements of pollutants from various diffuse or point sources which gives rise to coincidental mixtures in the ecosystem. Also, it can be found in food stuff such as imitation whip cream, unrefined grains and cereals, commercial peanut butter, hydrogenated vegetable oils, as well as contaminated alcoholic beverages . The use of lead-based paints should be abandoned, and lead should not be used in food containers. Potential risk effect from elevated levels of soil heavy metals on human health in the Niger delta. Three sampling sites associated with heavy anthropogenic activities along the course of the river were sampled. Chronic levels of mercury exposure can lead to erethism, a disease condition characterized by excitability, tremor of the hands, memory loss, timidity, and insomnia. A school of thought produced a mechanism for iron-induced cancer whereby bile acids (deoxycholic acid), iron(II) complexes, vitamins K and oxygen interact to generate free radicals which induced oncogenic effect in the colon. Lead is released into the atmosphere from industrial processes as well as from vehicle exhausts. Experimental studies confirmed that copper is also capable of inducing DNA strand breaks and oxidation of bases via oxygen free radicals . The DA reactive species are taken up by the dopamine transporter (DAT1) thus causing dopaminergic neurotoxicity . More focus will be laid on the various mechanisms that lead to heavy metal toxicity with emphasis on macromolecule and cellular damages, carcinogenesis, neurotoxicity and the molecular basis for their noxious effects. Lead can also reduce the expression of brain-derived neurotrophic factor (BDNF), a trans-synaptic signaling molecule that is released from both axons and dendrites which is involved in synaptic development and neurotransmitter release . This reaction further promotes damage of the lipid molecule. Edited by Ozgur Karcioglu and Banu Arslan. It has an average concentration in the soil of 5 to 6 mg/kg. The Cu2+ in the presence of biological reductants such as glutathione (GSH) or ascorbic acid can be reduced to Cu+ which is capable of catalyzing the decomposition of H2O2 to form OH• via the Fenton reaction  as shown below. Human Health in Areas with Industrial Contamination Edited by: Pierpaolo Mudu, Benedetto Terracini and Marco Martuzzi. But, heavy metals are the most damaging chemicals in water. These transcription factors control the expression of protective genes that induce apoptosis, arrest the proliferation of damaged cells, repair damaged DNA and power the immune system . Environ Epidemiol. Metals such as Pb, Cd, Hg, and As which do not play any beneficial role in plant growth, adverse effects have been recorded at very low concentrations of these metals in the growth medium. In such situations, the heavy metal-bound protein fits into an enzyme in a highly specific pattern to form an enzyme-substrate complex and thus cannot accommodate any other substrate until it is freed. Since these symptoms are also common in other illness or disease conditions, diagnosis of mercury poisoning may be difficult in such cases . Cadmium can cause bone mineralization as studies on animals and humans have revealed osteoporosis (skeletal damage) due to cadmium. For example, methylmercury (MeHg) strongly inhibits the activity ofl-glutamined-fructose-6-phosphate amidotransferase in yeast . Selenium modifies associations between multiple metals and neurologic symptoms in Gulf states residents. This has been further supported in electrophysiological studies in which recombinant receptors for the subunits have shown NR2A-NMDARs to be more potently inhibited by lead than NR2B-NMDARs . Heavy metals exhibit toxic effects towards soil biota by affecting key microbial Theses metals generally termed heavy metals include: antimony, tellurium, bismuth, tin, thallium, gold, arsenic, cerium, gallium, cadmium, chromium, cobalt, copper, iron, lead, mercury, manganese, nickel, platinum, silver, uranium, vanadium, and zinc [1, 2]. Asbestos contains about 30% of iron and thus workers who are highly exposed to asbestos are at high risk of asbestosis, a condition which is known to cause lung cancer. Exposure of extremely high doses of chromium (VI) compounds to humans can result in severe cardiovascular, respiratory, hematological, gastrointestinal, renal, hepatic, and neurological effects and possibly death . In the human body, these heavy metals are transported and compartmentalized into body cells and tissues binding to proteins, nucleic acids destroying these macromolecules and disrupting their cellular functions. The main threats to human health from heavy metals are associated with exposure to lead, cadmium, mercury and arsenic. | Heavy metals can be found in traces in water sources and still be very toxic and impose serious health problems to humans and other ecosystems. Arsenic can bind DNA-binding proteins and disrupt the DNA repair processes thereby increasing the risk of carcinogenesis. For example, the tumor suppressor gene-coded DNA was suppressed when arsenic was bound to methyl-transferase . 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