Heavy Metal And You Pdf


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Heavy metals are are elements that are naturally found in the earth.

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Acta Scientiae Veterinariae

Several heavy metals are found naturally in the earth crust and are exploited for various industrial and economic purposes. Among these heavy metals, a few have direct or indirect impact on the human body. 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.

However, some of these heavy metals in high doses can be harmful to the body while others such as cadmium, mercury, lead, chromium, silver, and arsenic in minute quantities have delirious effects in the body causing acute and chronic toxicities in humans.

The focus of this chapter is to describe the various mechanism of intoxication of some selected heavy metals in humans along with their health effects.

Therefore it aims to highlight on biochemical mechanisms of heavy metal intoxication which involves binding to proteins and enzymes, altering their activity and causing damage.

More so, the mechanism by which heavy metals cause neurotoxicity, generate free radical which promotes oxidative stress damaging lipids, proteins and DNA molecules and how these free radicals propagate carcinogenesis are discussed. Alongside these mechanisms, the noxious health effects of these heavy metals are discussed. Metals are natural constituents that exist in the ecosystem. They are substances with high electrical conductivity which voluntarily lose their electrons to form cations.

Metals are found all over the earth including the atmosphere, earth crust, water bodies, and can also accumulate in biological organisms including plants and animals. 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 ].

This category of metals termed heavy metals have not only been known for their high density but most importantly for their adverse effects to the ecosystem and living organisms [ 3 ].

Some of these heavy metals such as cobalt, chromium, copper, magnesium, iron, molybdenum, manganese, selenium, nickel and zinc are essential nutrients that are required for various physiological and biochemical functions in the body and may result to deficiency diseases or syndromes if not in adequate amounts [ 4 ] but in large doses they may cause acute or chronic toxicities. These heavy metals are distributed in the environment through several natural processes such as volcanic eruptions, spring waters, erosion, and bacterial activity, and through anthropogenic activities which include fossil fuel combustion, industrial processes, agricultural activities as well as feeding [ 5 ].

These heavy metals do bioaccumulate in living organisms and the human body through various processes causing adverse effects. 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.

As such, heavy metal toxicity can have several consequences in the human body. It can affect the central nervous function leading to mental disorder, damage the blood constituents and may damage the lungs, liver, kidneys and other vital organs promoting several disease conditions [ 6 ].

More so, repeated long-term contact with some heavy metals or their compounds may even damage nucleic acids, cause mutation, mimic hormones thereby disrupting the endocrine and reproductive system and eventually lead to cancer [ 7 ].

This chapter will highlight on the various sources of heavy metals and the processes that promote their exposure and bioaccumulation in the human body.

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. The various toxic effects along with the signs and symptoms of some heavy metals in the human body will be discussed. Heavy metals are naturally present in our environment.

They are present in the atmosphere, lithosphere, hydrosphere and biosphere [ 8 ]. Although these heavy metals are present in the ecosystem, their exposure to humans is through various anthropogenic activities of man. In the earth crust, these heavy metals are present in ores which are recovered during mining activities as minerals. In most ores heavy metals such as arsenic, iron, lead, zinc, gold, nickel, silver and cobalt exist as sulfides while others such as manganese, aluminum, selenium gold, and antimony exist as oxides.

Certain heavy metals such as copper, iron and cobalt can exist both as sulfide and oxide ores. Some sulfides may contain two or more heavy metals together such as chalcopyrite, CuFeS 2 which contains both copper and iron. During these mining activities, heavy metals are released from the ore and scattered in open in the environment; left in the soil, transported by air and water to other areas.

Furthermore, when these heavy metals are used in the industries for various industrial purposes, some of these elements are released into the air during combustion or into the soil or water bodies as effluents. More so, the industrial products such as paints, cosmetics, pesticides, and herbicides also serve as sources of heavy metals. Heavy metals may be transported through erosion, run-off or acid rain to different locations on soils and water bodies.

As reviewed from [ 9 ], the sources of specific heavy metals are described below. Arsenic is the 20th most abundant element on earth and the 33rd on the periodic table. The inorganic forms such as arsenite and arsenate compounds are lethal to humans and other organisms in the environment. Humans get in contact with arsenic through several means which include industrial sources such as smelting and microelectronic industries.

Drinking water may be contaminated with arsenic which is present in wood preservatives, herbicides, pesticides, fungicides and paints [ 10 ].

Lead is a slightly bluish, bright silvery metal in a dry atmosphere. The main sources of lead exposure include drinking water, food, cigarette, industrial processes and domestic sources. The industrial sources of lead include gasoline, house paint, plumbing pipes, lead bullets, storage batteries, pewter pitchers, toys and faucets [ 11 ]. Lead is released into the atmosphere from industrial processes as well as from vehicle exhausts. Therefore, it may get into the soil and flow into water bodies which can be taken up by plants and hence human exposure of lead may also be through food or drinking water [ 12 ].

The metallic mercury is a shiny silver-white, odorless liquid metal which becomes colorless and odorless gas upon heating. Mercury is used in producing dental amalgams, thermometers and some batteries. Also, it can be found in some chemical, electrical-equipment, automotive, metal-processing, and building industries.

Mercury can exist in a gaseous form thus it can be inhaled. 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 [ 13 ]. This metal is mostly used in industries for the production of paints, pigments alloys, coatings, batteries as well as plastics.

Majority of cadmium, about three-fourths is used as electrode component in producing alkaline batteries. 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.

Therefore, significant human exposure to cadmium can be by the ingestion of contaminated foodstuffs especially cereals, grains, fruits and leafy vegetables as well as contaminated beverages [ 14 , 15 ].

Also, humans may get exposed to cadmium by inhalation through incineration of municipal waste. Chromium is a metal that is present in petroleum and coal, chromium steel, pigment oxidants, fertilizers, catalyst, oil well drilling and metal plating tanneries. Chromium is extensively used in industries such as wood preservation, electroplating, metallurgy, production of paints and pigments, chemical production, tanning, and pulp and paper production. These industries play a major role in chromium pollution with an adverse effect on biological and ecological species [ 16 ].

Following the anthropogenic activities by humans, disposal of sewage and use of fertilizers may lead to the release of chromium into the environment [ 16 ].

Therefore, these industrial and agricultural practices increase the environmental contamination of chromium. Environmental pollution by chromium has been mostly by the hexavalent chromium in recent years [ 17 ]. This is a heavy metal which is used in industries to produce copper pipes, cables, wires, copper cookware, etc.

It is also used to make copper intrauterine devices and birth control pills. Copper in the form of copper sulfate is added to drinking water and swimming pools [ 18 ]. As such, copper is present in some nuts, avocado, wheat germ and bran etc. This metal is added to gasoline as methylcyclopentadienyl manganese tricarbonyl MMT and thus, gasoline fumes contain a very toxic form of manganese [ 19 ]. It is used in the production of batteries, nickel-plated jewelry, machine parts, nickel plating on metallic objects, manufacture of steel, cigarette smoking, wire, electrical parts, etc.

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 [ 19 ]. The various sources of heavy metals are summarized in Figure 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 [ 20 ].

The contamination chain of heavy metals almost usually follows this cyclic order: from industry, to the atmosphere, soil, water and foods then human [ 8 ]. These heavy metals can be taken up through several routes. Some heavy metals such as lead, cadmium, manganese, arsenic can enter the body through the gastrointestinal route; that is, through the mouth when eating food, fruits, vegetables or drinking water or other beverages.

Others can enter the body by inhalation while others such as lead can be absorbed through the skin. Most heavy metals are distributed in the body through blood to tissues [ 21 ]. Lead is carried by red blood cells to the liver and kidney and subsequently redistributed to the teeth, bone and hair mostly as phosphate salt [ 20 ]. Cadmium initially binds to blood cells and albumin, and subsequently binds to metallothionein in kidney and liver tissue.

Following its distribution from blood to the lungs, manganese vapor diffuses across the lung membrane to the Central nervous system CNS. Organic salts of manganese which are lipid soluble are distributed in the intestine for fecal elimination while inorganic manganese salts which are water soluble are distributed in plasma and kidney for renal elimination.

Arsenic is distributed in blood and accumulates in heart, lung, liver, kidney, muscle and neural tissues and also in the skin, nails and hair.

The regulatory limit for some selected heavy metals is shown in Table 1. Certain heavy metals are known to generate free radicals which may lead to oxidative stress and cause other cellular damages see [ 22 ] for review. The mechanism of free radical generation is specific to the type of heavy metal. 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.

It is well documented that metal-induced generation of oxygen reactive species can attack polyunsaturated fatty acid such as phospholipids. Following his experimental observations, he proposed the following mechanism:. This radical lipid further propagates the formation of peroxyl lipid radical by reacting with dioxygen molecule or with a lipid. This reaction further promotes damage of the lipid molecule.

The major aldehyde product of lipid peroxidation is malondialdehyde and it serves as a marker for lipid peroxidation. Generally, proteins are not easily damaged by H 2 O 2 and other simple oxidants unless transition metals are present. Experimental studies confirmed that copper is also capable of inducing DNA strand breaks and oxidation of bases via oxygen free radicals [ 27 ]. Though in vivo studies have not revealed copper-induced oxidation of low density lipoprotein LDL , in vitro studies clearly demonstrated LDL oxidation induced by copper [ 28 ].

Also, in vivo studies were able to show the detection of free radicals due to chromium in the liver and blood of animals. Vanadium is a heavy metal that occurs in various oxidative states and has been shown to generate free radical.

In the plasma, vanadium V is rapidly reduced to vanadium IV by NADPH and ascorbic acid antioxidants which bind to plasma proteins for transportation [ 31 ].

Some heavy metals are known to have carcinogenic effect. 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 [ 34 ].

Thus, heavy metals may induce carcinogenic effect by targeting a number of these proteins. 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 [ 22 ].

The p53 protein is an important protein in cell division as it guards a cell-cycle checkpoint and control cell division [ 35 ].

Scrap Metal Recycling 101 – A Guide For Complete Beginners

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Metrics details. Arsenic and heavy metals are the main cause of water pollution and impact human health worldwide. Therefore, this study aims to assess the probable health risk non-carcinogenic and carcinogenic risk for adults and children that are exposed to arsenic and toxic heavy metals Pb, Ni, Cr, and Hg through ingestion and dermal contact with drinking water. In this study, chemical analysis and testing were conducted on water samples taken from treated drinking water in Mashhad, Iran. Likewise, Cr showed the highest average contribution of HI total elements 55 to

Anything but heavy metal : Symbolic exclusion and musical dislikes

Phytic acid myoinositol hexaphosphate or its calcium salt, phytate, is an important plant constituent. Phytic acid has 12 replaceable protons in the phytic molecule, rendering it the ability to complex with multivalent cations and positively charged proteins. Poly 4-vinyl pyridine PVP and other strong-based resins have the ability to adsorb phytic acid.

Mechanism and Health Effects of Heavy Metal Toxicity in Humans

Several heavy metals are found naturally in the earth crust and are exploited for various industrial and economic purposes. Among these heavy metals, a few have direct or indirect impact on the human body.

Hot Brines and Recent Heavy Metal Deposits in the Red Sea

But after reading this guide, you may even feel pumped up enough to inspect your home for pieces of trash with metals in them. Mining is invasive. To extract raw materials from the earth, mining companies employ heavy excavators, haul trucks, and men with shovels to dig into the ground. This rabid digging not only destroys the soil, but it also releases toxic compounds, radioactive rocks, metallic dust, and asbestos-like minerals into the air and water. The impact extends far wider than the mining site itself, and continues decades after the mining activity is done. On the other hand, shutting down mining can prove devastating, too.

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A Quick Look At The Metal Recycling Process

В этот момент Сьюзан поймала себя на том, что готова взвалить на Хейла вину за все свои неприятности. За Цифровую крепость, волнения из-за Дэвида, зато, что не поехала в Смоуки-Маунтинс, - хотя он был ко всему этому не причастен. Единственная его вина заключалась в том, что она испытывала к нему неприязнь. Сьюзан важно было ощущать свое старшинство. В ее обязанности в качестве главного криптографа входило поддерживать в шифровалке мирную атмосферу - воспитывать .

 Вы можете заметить, - продолжал Смит, - что взгляд его устремлен. Он ни разу не посмотрел по сторонам. - Это так важно? - полувопросительно произнес Джабба. - Очень важно, - сказал Смит.  - Если бы Танкадо подозревал некий подвох, он инстинктивно стал бы искать глазами убийцу.

Будь он менее самонадеян, он, конечно же, заглянул бы в энциклопедию и обнаружил, что это не что иное, как солевой осадок, оставшийся после высыхания древних морей. Как и все криптографы АНБ, Хейл зарабатывал огромные деньги, однако вовсе не стремился держать этот факт при. Он ездил на белом лотосе с люком на крыше и звуковой системой с мощными динамиками. Кроме того, он был фанатом всевозможных прибамбасов, и его автомобиль стал своего рода витриной: он установил в нем компьютерную систему глобального позиционирования, замки, приводящиеся в действие голосом, пятиконечный подавитель радаров и сотовый телефонфакс, благодаря которому всегда мог принимать сообщения на автоответчик.

Наконец канадец опомнился. - Из консульства? - Его тон заметно смягчился. Беккер кивнул.

 Вернитесь назад, - приказала Сьюзан.  - Документ слишком объемный.

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