electronic waste components

7/30/2019 Electronic Waste Components

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A SEMINAR PRESENTED

BY

AKINSEYE, VICTOR OLUWATOYIN

MATRIC NO : 154687

SUBMMITED TO

CANCER RESEARCH AND MOLECULAR BIOLOGY

UNIT,

FACULTY OF BASIC MEDICAL SCIENCE,

UNIVERSITY OF IBADAN.

IN PARTIAL FULFILMENT FOR THE AWARD OF

DEGREE OF MASTER OF SCIENCE IN BIOCHEMISTRY.

FEBRUARY, 2011


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DEDICATION

This seminar write up is dedicated to Almighty God, the giver of wisdom,

knowledge, and understanding, and to my dearest parent Mr and Mrs F.K

Akinseye.


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ACKNOWLEDGEMENT

My special gratitude goes to Almighty God, the supreme being who has

being with me all this while. I want to appreciate Him for His mercy,

kindness and favour, may His name be praised forever.

I want to appreciate in a special way the effort of my parents Mr. and Mrs.

F.K. Akinseye, who God have been using as the brain behind my progress so

far, may God continue to grant good health of mind, body, and soul, Amen.

You are too much!

Kudos to my supervisor and the head of cancer research and molecular

biology unit, Dr O.A. Odunola, Dr. Owumi and Dr. Gbadegesin of cancer

research and molecular biology unit for their untiring effort and

understanding at time, may the Lord continue to grant success to the work of

your hand.

To all my colleagues especially cancer research and molecular biology unit,

may you always experience Gods goodness, Amen.

In a special way, I wish to express my sincere gratitude to the HOD

Department of Agronomy, Faculty of Agriculture, University of Ibadan for

his assistance and word of encouragement during the course of this research

work.

Finally, I wish to acknowledge my following friends and colleagues for

their assistance in the course of this work Tolu, Aboki, Ayo, Tobi, Fatoki,

Efe you guys are too much.


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TABLE OF CONTENT

1. INTRODUCTION

2. WHAT IS E-WASTE?

3. COMPONENTS OF E-WASTE.

3.1. Hazardous components

3.2. Generally non-hazardous components

4. E-waste and its effect on health and the environment

4.1. Effect of the hazardous e-waste component.

4.2. Biological importance of generally non hazardous component

5. MECHANISM OF TOXICITY OF SOME SELECTED METALS

5.1. Lead

5.2 Cadmium

5.3 Mercury

5.4 Chromium


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INTRODUCTION

The production of electrical and electronic equipment (EEE) is one of the fastest

growing global manufacturing activities. Rapid economic growth, coupled with

urbanization and a growing demand for consumer goods, has increased both the

consumption and the production of EEE[Ramech et al ,2007]. The Indian information

technology (IT) industry has been one of the major drivers of change in the economy in

the last decade and has contributed significantly to the digital revolution being

experienced by the world. New electronic gadgets and appliances have infiltrated every

aspect of our daily lives, providing our society with more comfort, health and security

and with easy information acquisition and exchange[Sincha et al, 2007]. The knowledge

society however is creating its own toxic footprints.

The same hypertechnology that is hailed as a crucial vector for future modern societal

development has a not-so-modern downside to it: electronic waste (e-waste)[Swerts T et

al, 2006]. E-waste broadly covers waste from all electronic and electrical appliances and

comprises of items such as computers, mobile phones, digital music recorders/players,

refrigerators, washing machines, televisions (TVs) and many other household consumer

items.[Sincha S et al, 2007]

The increasing market penetration in the developing countries, replacement market in

the developed countries and high obsolescence rate make e-waste one of the fastest

waste streams. This new kind of waste is posing a serious challenge in disposal and

recycling to both developed and developing countries. While having some of the world's

most advanced high-tech software and hardware developing facilities, India's recycling

sector can be called medieval.[Swerts T et al, 2006] The dumping of e-waste, particularly

computer waste, into underdeveloped and developing countries from developed

countries[Wankhede K et al, 2005] (green passport according to Gutierrez), because thelatter find it convenient and economical to export waste, has further complicated the

problems with waste management.

A lot of the reasoning behind the need to control e-waste is for its health and

environmental effects. The chemicals and metals usually put into the manufacturing and

production of electronics contain properties harmful to our bodies, sometimes their


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effects are not noticeable right away and often not harmful until the electronics' end of

life. Much of the substances in computers are not biodegradable. The toxic metals

contained in them are contaminating the water, air, and soil. When these elements are

safely encased in our refrigerators and laptops, e-waste dangers aren't much of an issue.

Problems can occur when devices break -- intentionally or accidentally. Then they can

leak and contaminate their immediate environment, whether that's in a landfill or on the

streets within a region full of struggling laborers. Over time, the toxic chemicals of a

landfill's e-waste can seep into the ground (possibly entering the water supply) or escape

into the atmosphere, affecting the health of nearby communities.

How? When this materials are disposed, their components i.e. heavy metals and other

harmful components leaches into the underground water and surrounding water bodies,

they contaminates these water sources, thus posing a health risk. Also when some of

them are burnt, these heavy metals are released into the atmosphere, thus polluting the

air. Properly recycling of electronics waste would not only be a benefit to our

environment but for our health.

Unfortunately, if these hazardous components within computers are not disposed off

carefully they can cause permanent health issues. Some of the common harmful heavy

metals are lead, mercury, chromium, and beryllium. In nature these metals are sometimes

harmless but when used to manufacture electronics, often result in compounds that are

hazardous. For example, chromium becomes chromium VI as it is used in floppy disks

and to protect metal parts from corrosion; exposure can cause permanent eye injury,

DNA damage, and cancer.

The fifth most widely used metal is lead. Lead is used in solder, batteries, cable sheathing

and in the glass of cathode ray tubes for computer monitors. Short-term high exposure tolead can cause appetite loss, fatigue, vomiting, diarrhea, convulsions, coma or even death.

Long-term exposure, as in an industrial setting, can cause damage to the nervous, blood

and reproductive systems in adults. Children and pregnant women that are exposed to

lead can suffer from damage to their nervous connections and cause brain disorders.

One of the most toxic metals used in the production of electronics is mercury. It can be
http://home.howstuffworks.com/refrigerator.htmhttp://science.howstuffworks.com/landfill.htmhttp://science.howstuffworks.com/landfill.htmhttp://home.howstuffworks.com/refrigerator.htm


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found in flat screen displays, switches, housing, thermostats, and florescent lamps.

Mercury is a metal that accumulates in living organisms causing brain and liver damage

if ingested or inhaled. Lastly, there is beryllium, which has recently been classified as a

human carcinogen because exposure to it can cause lung cancer. Workers exposed to

beryllium, even in small amounts, can develop what is known as Chronic Beryllium

Disease (beryllicosis). Studies have shown that people can still develop beryllium

diseases years from the last exposure. Granted, the metals stated above are only a few of

the many hazardous materials contained in our electronics. To better understand the scale

we are talking about, take the example of a cellphone that contains 500 to 1000

components.

Due to poor regulations on e-waste recycling in developing countries a lot of the methods

used to retrieve certain metals from electronics are polluting the environment. A report

done in 2007 by the Chinese Academy of Science found that Guiyu, China has the

world's highest levels of environmental pollutants that threaten human health. Pollutants

are released into the air through the burning of plastics and circuit boards coated with

flame retardants to extract gold, platinum, copper and other metals. About 1.7 million

tonnes of e-waste is processed each year in Guiyu. Shantou health researchers found in a

study from 2008 that 81 percent of blood samples from Guiyu infants has significantly

higher levels of blood lead and high levels of cadmium in 20.1 percent of infants. The

research indicates that these levels are leading to stillbirths, low birth weights, premature

deliveries and impacts on child growth rates and nervous developments. Developed

countries and places that are not home to e-waste landfills are not completely excluded

from the effect of e-waste.

Pollutants in the air are able to travel across the Pacific and into our air. As a result of the

waste not properly monitored, it can seep into the ground and water. Mercury is a

commonly known metal found in fish populations which seems to have a tie to e-waste

harming bodies of water.


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WHAT IS E-WASTE

Electronic waste, e-waste, e-scrap, or Waste Electrical and Electronic Equipment

(WEEE) describes loosely discarded, surplus, obsolete, or broken electrical or electronic

devices. Electronic waste may be defined as all secondary computers, entertainment

device electronics, mobile phones, and other items such as television sets and

refrigerators, whether sold, donated, or discarded by their original owners.

This definition includes used electronics which are destined for reuse, resale, salvage,

recycling, or disposal. Others define the re-usables (working and repairable electronics)

and secondary scrap (copper, steel, plastic, etc.) to be commodities, and reserve the

term waste for residue or material which was represented as working or repairable but

which is dumped or disposed or discarded by the buyer rather than recycled, including

residue from reuse and recycling operations. Because loads of surplus electronics are

frequently commingled (good, recyclable, and non-recyclable), several public policy

advocates apply the term e-waste broadly to all surplus electronics.

Electronic-waste (or e-waste) is a collective name for trashed electronic items like

obsolete PCs, laptops, fax machines, cell phones, batteries, consumer electronics etc.E-

waste is a term used to cover almost all types of electrical and electronic equipment that

has or could enter the waste stream. Although e-waste is a general term, it can be often

considered to cover TVs, computers, mobile phones, white goods (fridges, washing

machines, dryers etc.), home entertainment and stereo systems, toys, toasters, kettles

almost any household or business item with circuitry or electrical components with power

or battery supply. This definition includes used electronics which are destined for reuse,

resale, salvage, recycling, or disposal. Others define the re-usables (working and

repairable electronics) and secondary scrap (copper, steel, plastic, etc.) to be"commodities", and reserve the term "waste" for residue or material which was

represented as working or repairable but which is dumped or disposed or discarded by the

buyer rather than recycled, including residue from reuse and recycling operations.

Because loads of surplus electronics are frequently commingled (good, recyclable, and

non-recyclable), several public policy advocates apply the term "e-waste" broadly to all

surplus electronics.
http://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Steelhttp://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Plastichttp://en.wikipedia.org/wiki/Steelhttp://en.wikipedia.org/wiki/Copper


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E-waste is any refuse created by discarded electronic devices and components as well as

substances involved in their manufacture or use. The disposal of electronics is a growing

problem because electronic equipment frequently contains hazardous substances. In a

personal computer, for example, there may be lead in the cathode ray tube (CRT) and

soldering compound, mercury in switches and housing, and cobalt in steel components,

among other equally toxic substances. According to the Environmental Protection

Agency (EPA), more than four million tons of e-waste go to U.S. landfills each year.

Electronic waste or e-waste is the term used to describe old, end-of-life electronic

appliances such as computers, laptops, TVs, DVD players, mobile phones, mp3 players,

etc., which have been disposed by their original users.

E-waste has been categorized into three main categories, i.e., Large Household

Appliances, IT and Telecom and Consumer Equipment. Refrigerator and washing

machine represent large household appliances; PC, monitor and laptop represent IT and

Telecom, while TV represents Consumer Equipment.

Each of these e-waste items has been classified with respect to 26 common components

found in them. These components form the building blocks of each item and therefore

they are readily identifiable and removable. These components are metal, motor/

compressor, cooling, plastic, insulation, glass, LCD, rubber, wiring/electrical, concrete,

transformer, magnetron, textile, circuit board, fluorescent lamp, incandescent lamp,

heating element, thermostat, brominated flamed retardant (BFR)-containing plastic,

batteries, CFC/HCFC/HFC/HC, external electric cables, refractory ceramic fibers,

radioactive substances and electrolyte capacitors (over L/D 25 mm).

The composition of WEEE/e-waste is very diverse and differs in products across different

categories. It contains more than 1000 different substances, which fall under hazardous

and non-hazardous categories. Broadly, it consists of ferrous and non-ferrous metals,

plastics, glass, wood and plywood, printed circuit boards, concrete and ceramics, rubber

and other items. Iron and steel constitutes about 50% of the WEEE followed by plastics

(21%), non-ferrous metals (13%) and other constituents. Non-ferrous metals consist of

metals like copper, aluminium and precious metals, e.g. silver, gold, platinum, palladium,

etc. The presence of elements like lead, mercury, arsenic, cadmium, selenium and

hexavalent chromium and flame retardants beyond threshold quantities in WEEE/e-waste

classifies them as hazardous waste.


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COMPONENTS OF ELECTRONIC WASTE

Some computer components can be reused in assembling new computer products, while

others are reduced to metals that can be reused in applications as varied as construction,

flatware, and jewelry[Haffenreffer D. et al, 2003]

Substances found in large quantities include epoxy resins, fiberglass, PCBs, PVC

(polyvinyl chlorides), thermosetting plastics, lead, tin, copper, silicon, beryllium, carbon,

iron and aluminium.

Elements found in small amounts include cadmium, mercury, and thallium[Becker et al,

2005].

Elements found in trace amounts include americium, antimony, arsenic, barium, bismuth,

boron,cobalt, europium, gallium, germanium, gold, indium, lithium, manganese, nickel,

niobium,palladium, platinum, rhodium, ruthenium, selenium, silver, tantalum, terbium,

thorium, titanium, vanadium, and yttrium.

Almost all electronics contain lead and tin (as solder) and copper (as wire and printed

circuit board tracks), though the use of lead-free solder is now spreading rapidly

The components of electronic waste can be arbitrarily divided into two based on their

effects : Hazardous components and Generally nonhazardous component

Hazardous components

Americium: Smoke Alarms (radioactive source).Mercury: Fluorescent Tubes (numerous applications), tilt switches (pinball games,mechanical doorbells, thermostats). There are no liquid mercury switches in ordinary

computers, and the elimination of mercury batteries in many new-model computers is

taking place.[28]

Sulphur: Lead-Acid Batteries.PBBs: Predecessor of PCBs. Also used as flame retardant. Banned from 1973-1977 on.PCBs: Prior to ban, almost all 1930s1970s equipment, including capacitors,transformers, wiring insulation, paints, inks, and flexible sealants. Banned during the

1980s.

Cadmium: Light-sensitive resistors, corrosion-resistant alloys for marine and aviationenvironments, nickel-cadmium batteries.
http://en.wikipedia.org/wiki/Epoxy#Electrical_systems_and_electronicshttp://en.wikipedia.org/wiki/Fiberglasshttp://en.wikipedia.org/wiki/PCBshttp://en.wikipedia.org/wiki/PVChttp://en.wikipedia.org/wiki/Thermosetting_plasticshttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Tinhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Berylliumhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Mercury_%28element%29http://en.wikipedia.org/wiki/Thalliumhttp://en.wikipedia.org/wiki/Thalliumhttp://en.wikipedia.org/wiki/Americiumhttp://en.wikipedia.org/wiki/Antimonyhttp://en.wikipedia.org/wiki/Arsenichttp://en.wikipedia.org/wiki/Bariumhttp://en.wikipedia.org/wiki/Bismuthhttp://en.wikipedia.org/wiki/Boronhttp://en.wikipedia.org/wiki/Cobalthttp://en.wikipedia.org/wiki/Europiumhttp://en.wikipedia.org/wiki/Galliumhttp://en.wikipedia.org/wiki/Germaniumhttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Indiumhttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/Manganesehttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/Niobiumhttp://en.wikipedia.org/wiki/Palladiumhttp://en.wikipedia.org/wiki/Platinumhttp://en.wikipedia.org/wiki/Rhodiumhttp://en.wikipedia.org/wiki/Rutheniumhttp://en.wikipedia.org/wiki/Seleniumhttp://en.wikipedia.org/wiki/Silverhttp://en.wikipedia.org/wiki/Tantalumhttp://en.wikipedia.org/wiki/Terbiumhttp://en.wikipedia.org/wiki/Thoriumhttp://en.wikipedia.org/wiki/Titaniumhttp://en.wikipedia.org/wiki/Vanadiumhttp://en.wikipedia.org/wiki/Yttriumhttp://en.wikipedia.org/wiki/Printed_circuit_boardhttp://en.wikipedia.org/wiki/Printed_circuit_boardhttp://en.wikipedia.org/wiki/Americiumhttp://en.wikipedia.org/wiki/Americiumhttp://en.wikipedia.org/wiki/Americiumhttp://en.wikipedia.org/wiki/Smoke_alarmhttp://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Fluorescent_tubehttp://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Electronic_waste#cite_note-27http://en.wikipedia.org/wiki/Electronic_waste#cite_note-27http://en.wikipedia.org/wiki/Electronic_waste#cite_note-27http://en.wikipedia.org/wiki/Sulphurhttp://en.wikipedia.org/wiki/Sulphurhttp://en.wikipedia.org/wiki/Sulphurhttp://en.wikipedia.org/wiki/Lead-acid_batterieshttp://en.wikipedia.org/wiki/Polybrominated_biphenylhttp://en.wikipedia.org/wiki/Polybrominated_biphenylhttp://en.wikipedia.org/wiki/Polychlorinated_biphenylhttp://en.wikipedia.org/wiki/Polychlorinated_biphenylhttp://en.wikipedia.org/wiki/Polychlorinated_biphenylhttp://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Nickel-cadmium_batterieshttp://en.wikipedia.org/wiki/Nickel-cadmium_batterieshttp://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Polychlorinated_biphenylhttp://en.wikipedia.org/wiki/Polybrominated_biphenylhttp://en.wikipedia.org/wiki/Lead-acid_batterieshttp://en.wikipedia.org/wiki/Sulphurhttp://en.wikipedia.org/wiki/Electronic_waste#cite_note-27http://en.wikipedia.org/wiki/Thermostathttp://en.wikipedia.org/wiki/Fluorescent_tubehttp://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Smoke_alarmhttp://en.wikipedia.org/wiki/Americiumhttp://en.wikipedia.org/wiki/Printed_circuit_boardhttp://en.wikipedia.org/wiki/Printed_circuit_boardhttp://en.wikipedia.org/wiki/Yttriumhttp://en.wikipedia.org/wiki/Vanadiumhttp://en.wikipedia.org/wiki/Titaniumhttp://en.wikipedia.org/wiki/Thoriumhttp://en.wikipedia.org/wiki/Terbiumhttp://en.wikipedia.org/wiki/Tantalumhttp://en.wikipedia.org/wiki/Silverhttp://en.wikipedia.org/wiki/Seleniumhttp://en.wikipedia.org/wiki/Rutheniumhttp://en.wikipedia.org/wiki/Rhodiumhttp://en.wikipedia.org/wiki/Platinumhttp://en.wikipedia.org/wiki/Palladiumhttp://en.wikipedia.org/wiki/Niobiumhttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/Manganesehttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/Indiumhttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Germaniumhttp://en.wikipedia.org/wiki/Galliumhttp://en.wikipedia.org/wiki/Europiumhttp://en.wikipedia.org/wiki/Cobalthttp://en.wikipedia.org/wiki/Boronhttp://en.wikipedia.org/wiki/Bismuthhttp://en.wikipedia.org/wiki/Bariumhttp://en.wikipedia.org/wiki/Arsenichttp://en.wikipedia.org/wiki/Antimonyhttp://en.wikipedia.org/wiki/Americiumhttp://en.wikipedia.org/wiki/Thalliumhttp://en.wikipedia.org/wiki/Mercury_%28element%29http://en.wikipedia.org/wiki/Cadmiumhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Berylliumhttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Tinhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Thermosetting_plasticshttp://en.wikipedia.org/wiki/PVChttp://en.wikipedia.org/wiki/PCBshttp://en.wikipedia.org/wiki/Fiberglasshttp://en.wikipedia.org/wiki/Epoxy#Electrical_systems_and_electronics


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Lead: Solder, CRT monitor glass, lead-acid batteries, some formulations of PVC.[29]Atypical 15-inch cathode ray tube may contain 1.5 pounds of lead,[1]but other CRTs have

been estimated as having up to 8 pounds of lead.[11]

Beryllium oxide: Filler in some thermal interface materials such as thermal grease usedon heatsinks for CPUs and power transistors,[30] magnetrons, X-ray-transparent ceramic

windows, heat transfer fins in vacuum tubes, and gas lasers.

Polyvinyl chloride: Third most widely produced plastic, contains additional chemicalsto change the chemical consistency of the product. Some of these additional chemicals

called additives can leach out of vinyl products. Plasticizers that must be added to make

PVC flexible have been additives of particular concern. Burning PVC in connection with

humidity in the air creates Hydrogen Chloride (HCl), an acid.

Generally non-hazardous components

Tin: Solder, coatings on component leads.Copper: Copper wire, printed circuit board tracks, component leads.Aluminium: Nearly all electronic goods using more than a few watts of power(heatsinks), electrolytic capacitors.

Iron: Steel chassis, cases, and fixings.Germanium: 1950s1960s transistorized electronics (bipolar junction transistors).Silicon: Glass, transistors, ICs, printed circuit boards.Nickel: nickel-cadmium batteries.Lithium: lithium-ion batteries.Zinc: plating for steel parts.Gold: connector plating, primarily in computer equipment.
http://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Leadhttp://en.wikipedia.org/wiki/Solderhttp://en.wikipedia.org/wiki/Lead-acid_batterieshttp://en.wikipedia.org/wiki/Electronic_waste#cite_note-28http://en.wikipedia.org/wiki/Electronic_waste#cite_note-28http://en.wikipedia.org/wiki/Electronic_waste#cite_note-28http://en.wikipedia.org/wiki/Electronic_waste#cite_note-sb-0http://en.wikipedia.org/wiki/Electronic_waste#cite_note-sb-0http://en.wikipedia.org/wiki/Electronic_waste#cite_note-sb-0http://en.wikipedia.org/wiki/Electronic_waste#cite_note-smith-10http://en.wikipedia.org/wiki/Electronic_waste#cite_note-smith-10http://en.wikipedia.org/wiki/Electronic_waste#cite_note-smith-10http://en.wikipedia.org/wiki/Beryllium_oxidehttp://en.wikipedia.org/wiki/Beryllium_oxidehttp://en.wikipedia.org/wiki/Beryllium_oxidehttp://en.wikipedia.org/wiki/Thermal_greasehttp://en.wikipedia.org/wiki/Heatsinkhttp://en.wikipedia.org/wiki/CPUhttp://en.wikipedia.org/wiki/Power_semiconductor_devicehttp://en.wikipedia.org/wiki/Electronic_waste#cite_note-apmag-29http://en.wikipedia.org/wiki/Electronic_waste#cite_note-apmag-29http://en.wikipedia.org/wiki/Magnetronhttp://en.wikipedia.org/wiki/Vacuum_tubehttp://en.wikipedia.org/wiki/Gas_laserhttp://en.wikipedia.org/wiki/Polyvinyl_chloridehttp://en.wikipedia.org/wiki/Polyvinyl_chloridehttp://en.wikipedia.org/wiki/Tinhttp://en.wikipedia.org/wiki/Tinhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Printed_circuit_boardhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Heatsinkhttp://en.wikipedia.org/wiki/Electrolytic_capacitorhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Germaniumhttp://en.wikipedia.org/wiki/Germaniumhttp://en.wikipedia.org/wiki/Germaniumhttp://en.wikipedia.org/wiki/Bipolar_junction_transistorhttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Glasshttp://en.wikipedia.org/wiki/Transistorhttp://en.wikipedia.org/wiki/Integrated_circuithttp://en.wikipedia.org/wiki/Printed_circuit_boardhttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/Nickel-cadmium_batterieshttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/Lithium-ion_batterieshttp://en.wikipedia.org/wiki/Zinchttp://en.wikipedia.org/wiki/Zinchttp://en.wikipedia.org/wiki/Zinchttp://en.wikipedia.org/wiki/Platinghttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Gold_platinghttp://en.wikipedia.org/wiki/Gold_platinghttp://en.wikipedia.org/wiki/Goldhttp://en.wikipedia.org/wiki/Platinghttp://en.wikipedia.org/wiki/Zinchttp://en.wikipedia.org/wiki/Lithium-ion_batterieshttp://en.wikipedia.org/wiki/Lithiumhttp://en.wikipedia.org/wiki/Nickel-cadmium_batterieshttp://en.wikipedia.org/wiki/Nickelhttp://en.wikipedia.org/wiki/Printed_circuit_boardhttp://en.wikipedia.org/wiki/Integrated_circuithttp://en.wikipedia.org/wiki/Transistorhttp://en.wikipedia.org/wiki/Glasshttp://en.wikipedia.org/wiki/Siliconhttp://en.wikipedia.org/wiki/Bipolar_junction_transistorhttp://en.wikipedia.org/wiki/Germaniumhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Electrolytic_capacitorhttp://en.wikipedia.org/wiki/Heatsinkhttp://en.wikipedia.org/wiki/Aluminiumhttp://en.wikipedia.org/wiki/Printed_circuit_boardhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Tinhttp://en.wikipedia.org/wiki/Polyvinyl_chloridehttp://en.wikipedia.org/wiki/Gas_laserhttp://en.wikipedia.org/wiki/Vacuum_tubehttp://en.wikipedia.org/wiki/Magnetronhttp://en.wikipedia.org/wiki/Electronic_waste#cite_note-apmag-29http://en.wikipedia.org/wiki/Power_semiconductor_devicehttp://en.wikipedia.org/wiki/CPUhttp://en.wikipedia.org/wiki/Heatsinkhttp://en.wikipedia.org/wiki/Thermal_greasehttp://en.wikipedia.org/wiki/Beryllium_oxidehttp://en.wikipedia.org/wiki/Electronic_waste#cite_note-smith-10http://en.wikipedia.org/wiki/Electronic_waste#cite_note-sb-0http://en.wikipedia.org/wiki/Electronic_waste#cite_note-28http://en.wikipedia.org/wiki/Lead-acid_batterieshttp://en.wikipedia.org/wiki/Solderhttp://en.wikipedia.org/wiki/Lead


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The graphs of large household appliance

E-WASTE AND ITS EFFECT ON HEALTH AND THE ENVIRONMENT

E-waste cannot be considered or treated like any kind of waste, because it contains

hazardous and toxic substances such as lead, mercury, cadmium or others such as dioxins

and furans, bromined flame retardants (produced when e-waste is incinerated). For

instance, lead represents 6% of the total weight of a computer monitor. Another example:

nearly 36 chemical elements are incorporated in electronic equipment.

EEEs are made of a multitude of components, some containing toxic substances that

have an adverse impact on human health and the environment if not handled properly.

Often, these hazards arise due to the improper recycling and disposal processes used. It

can have serious repercussions for those in proximity to places where e-waste is recycled

or burnt. Waste from the white and brown goods is less toxic as compared with grey

goods. A computer contains highly toxic chemicals like lead, cadmium, mercury,

beryllium, BFR, polyvinyl chloride and phosphor compounds.


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For instance, lead represents 6% of the total weight of a computer monitor. Another

example: nearly 36 chemical elements are incorporated in electronic equipment. Even

though in the last years recycling has become a regular practice almost everywhere in the

world, some e-waste components present difficulties when they are recycled mainly

because of their complexity and the lack of methods. Such is the case of plastics used in

electronic equipment which contain flame retardants that impede the recycling process.

Table 1 : Environment and health hazards

Computer/e-

waste

component

Process

Potential

occupational

hazard

Potential

environmenta

l hazard

Cathode ray

tubes

Cathode ray

tubes and

dumping

Silicosis,

Cuts from CRT

glass,

Inhalation or

contact with

phosphor

containing

cadmium or

other metals

Lead, barium

and other

heavy metals

leaching into

ground water

and release of

toxic phosphor

Printer

circuit

boards

Desoldering

and

removing

computer

chips

Tin and lead

inhalation,

Possible

brominated

dioxin,

Air emission of

the same

substances


14/41

beryllium,

cadmium and

mercury

inhalation

Dismantled

printed

circuit board

processing

Open

burning of

waste boards

Toxicity of

workers and

nearby residents

rom tin, lead,

brominated

dioxin,

beryllium,

cadmium and

mercury

inhalation

Tin and lead

contamination

of immediate

environment,

including

surface and

ground waters,

brominated

dioxins,

beryllium,

cadmium and

mercury

inhalation

Chips and

other gold-

plated

compounds

Chemical

stripping

using nitric

and

hydrochloric

acid along

riverbanks

Acid contact

with eyes, skin

may result in

permanent

injury

Inhalation if

mists and fumes

of acids,

chlorine and

sulfur dioxide

gases can cause

respiratory

irritation to

severe effects,

including

pulmonary

Hydrocarbons,

heavy metals,

brominated

substances etc.

discharged

directly into

river and

banks.

Acidifies the

river

destroying fish

and flora


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edema,

circulatory

failure and

death

Plastics from

the computer

and

peripherals

Shredding

and low-

temperature

melting

Probable

hydrocarbon,

brominated

dioxin and PAH

exposure to

workers living

in the burning

works area

Emission of

brominated

dioxins and

heavy metals

and

hydrocarbons

Secondary

steel or

copper and

precious

metal

smelting

Furnace

recovers

steel or

copper from

waste

Exposure to

dioxins and

heavy metals

Emission of

dioxins and

heavy metals

Wires Open

burning to

recover

copper

Brominated and

chlorinated

dioxin and PAH

exposure to

workers living

in the burning

works area

Hydrocarbon

and ashes,

including

PAHs

discharged into

air, water and

soil

EFFECTS OF THE HAZARDOUS E-WASTE COMPONENETS


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Lead

Lead is found in many electronic equipment components. For example, in a PC, the

largest amount of this metal is found in the CRT of the monitor: 0 to 3% in the panel,

70% in the frit, 24% in the funnel and 30% in the neck. Lead is also present in weldings

(40%), motherboards, circuits and wiring plastic. Humans are exposed to this metal by

particle inhalation and through contaminated foods. The first effects and symptoms of

lead exposure are anorexia, muscle pain, malaise and headache but an extended exposure

can cause a decrease in nervous system performance, weakness, brain damage and even

death. Lead exerts toxic effects on various systems in the body such as the central

(organic affective syndrome) and peripheral nervous systems (motor neuropathy), the

hemopoietic system (anemia), the genitourinary system (capable of causing damage to all

parts of nephron) and the reproductive systems (male and female).

Likewise, it can affect the reproductive system both in men and women and is

considered carcinogen. The chemical structure of this metal is directly affected by its pH

but most lead compounds are insoluble in water and remain in that state. They are

difficultly accumulated in plants or transferred to food. Lead doesnt bio-accumulate in

fish but it does in other seafood. If broken or incinerated to the environment, particles

will be transmitted by air and soil.

Lithium

Lithium is present in computer batteries and modern electronic equipment. Typically

batteries contain an anode of lithium or lithium oxide, a magnesium dioxide (magnesium

oxide and carbon) cathode and lithium salt dissolved in anorganic solvent. This type of

batteries replaces alkaline and NiCd batteries. It is environmentally more sustainable than

its predecessors. Lithium is present in computer batteries and modern electronic

equipment. Typically batteries contain an anode of lithium or lithium oxide, a magnesium

dioxide (magnesium oxide and carbon) cathode and lithium salt dissolved in an organic

solvent. This type of batteries replaces alkaline and NiCd batteries. It is environmentallymore sustainable than its predecessors.

Mercury

Mercury is found in three specific places in a computer. The largest amount is found in

LCD screen fluorescent light, computer or monitor switches, which enable them to shut

down while idle, and finally in batteries. Mercury is very volatile and easily liberated by


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Cadmium (Cd)

Cadmium is a heavy metal included in many electronic components, such as contact

plates, switches, or used to prevent corrosion. Cadmium is particularly found in chip

resistors, infrared detectors, and semiconductors. Old monitors contain around 5 to 10

grams of Cadmium and some batteries are made of Nickel Cadmium. It is added as a

plastic stabilizer and pigment to wiring, motherboards, pcs, monitors and printed circuit

boards.

Cadmium exposure commonly occurs through inhalation and ingestion of food or

contaminated water. Inhaling large amounts of Cadmium can cause lung damage and

death. Exposure to small amounts over a long period of time can cause high pressure and

kidney damage. This metal is a carcinogen. Cadmium enters the environment through

water and soil that is absorbed by plants. Low concentrations can cause alterations in the

ecology and balance of soil nutrients.This metal can bio-accumulate in mushrooms,

oysters, shrimps, mussels and fish. Cadmium is a potentially long-term cumulative

poison. Toxic cadmium compounds accumulate in the human body, especially in the

kidneys. There is evidence of the role of cadmium and beryllium in carcinogenicity.

Chromium IV(Cr +6)

Chromium VI, i.e. chromium ions with a charge of +6, is chromiums only toxic form. Its

presence is small in electronic equipment where it is used as a plastic hardener and

protection layer for some metal components. When electronic components are burned,

99% of Chromium VI stays in residuals and ashes, contaminating soil in a toxic way,

which could reach water currents with significant higher risk. Chromium VI, i.e.

chromium ions with a charge of +6, is chromiums only toxic form. Its presence is small

in electronic equipment where it is used as a plastic hardener and protection layer for

some metal components. When electronic components are burned, 99% of Chromium VIstays in residuals and ashes, contaminating soil in a toxic way, which could reach water

currents with significant higher risk.


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Polycyclic aromatic hydrocarbons (PAH)

Affects lung, skin and bladder. Epidemiological studies in the past on occupational

exposure to PAH provide sufficient evidence of the role of PAH in the induction of skin

and lung cancers.

Polychlorinated Biphenyl (PCB)

Humans are exposed through contaminated food consumption or direct contact at their

workplace, (e.g inadequate disassembly of electronic equipment). Exposure to this

compound can cause anemia, damages to the skin, liver, stomach and thyroid.

Contamination of pregnant women is very risky and research results show that it can be

carcinogenic. This chemical compound could drip through subsurface layers reaching

water and contaminating it if buried in landfills.

Because it is poorly soluble, it is very dangerous when it enters water currents as it could

contaminate the chain of production of some foods.

Tetra Bromo Bisphenol-A (TBBPA)

It has not been proved that it can cause mutations or carcinogen effects on human beings.

Nevertheless, it has been proved that TBBA may interfere in the transport and

metabolism of some hormones. A technical study has demonstrated that there is a direct

correlation between TBBA in the blood flow and in the air. TBBA is toxic to aquatic

organisms. Unlike other flame-retardants, TBBA when used as a reactive, bounds

chemically to plastic or polymers for protection. This impedes its liberation into the

environment. It is biodegradable but one of the products of this biodegradation is

bisphenol which can cause damages to the endocrine system. The fact that TBBA

dissolves poorly in water and tends to adhere to soil, where it can reach food, has created

great concern because TBBA levels magnify while passing through the food chain from

20 to 3200 times.

Polybrominated Biphenyls (PBB)

Exposure to this substance can damage kidneys, liver and thyroids. Fetuses that were

exposed to PBB had endocrinal problems. Likewise it is suspected that PBB is a

carcinogen it dissolves poorly in water but can adhere strongly to soil, through which it

could reach food. It keeps magnifying while passing along the food chain.


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BIOLOGICAL IMPORTANCE OF NON HAZARDOUS E-WASTE

COMPONENTS

Some components of electronic waste are relatively non-toxic to the living system,

however their reaction with other compound can pose a health threat. Metals like tin,

copper, iron , germanium, silicon, nickel, lithium, zinc, gold e.t.c. perform one or two

biological importance in the maintenance of the normal body functions. Some of these

uses include:

1. ZincIn the periodic table of the elements, zinc can be found in group IIb, together with the

two toxic metals cadmium and mercury. Nevertheless, zinc is considered to be relatively

non-toxic to humans [Fosmire GJ et al,1990.]. This is reflected by a comparison of the

LD50 of the sulfate salts in rats. According to the Toxnet database of the U.S. National

Library of Medicine, the oral LD50 for zinc is close to 3 g/kg body weight, more than 10-

fold higher than cadmium and 50-fold higher than mercury [U.SNat.Lib. fo Med.,2010.].

An important factor seems to be zinc homeostasis, allowing the efficient handling of an

excess of orally ingested zinc, because after intraperitoneal injection into mice, the LD50

for zinc was only approximately four-fold higher than for cadmium and mercury [Jones

MM et al,1993.]. In contrast to the other two metals, for which no role in human

physiology is known, zinc is an essential trace element not only for humans, but for all

organisms.

It is a component of more than 300 enzymes and an even greater number of other

proteins, which emphasizes its indispensable role for human health. Optimal nucleic acid

and protein metabolism, as well as cell growth, division, and function, require sufficient

availability of zinc [VallenBL et al,1993].

The human body contains 23 g zinc, and nearly 90% is found in muscle and bone

[Wastney ME et al,1986.]. Other organs containing estimable concentrations of zinc

include prostate, liver, the gastrointestinal tract, kidney, skin, lung, brain, heart, and
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2872358/?tool=pmcentrez#b2-ijerph-07-01342http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2872358/?tool=pmcentrez#b2-ijerph-07-01342http://www.ncbi.nlm.nih.gov/pubmed/8419966http://www.ncbi.nlm.nih.gov/pubmed/8419966http://www.ncbi.nlm.nih.gov/pubmed/8419966http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2872358/?tool=pmcentrez#b2-ijerph-07-01342


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pancreas [Bentley BJ, et al,1991, He LS et al,1991, Liobet JM et al,1988.]. Oral uptake of

zinc leads to absorption throughout the small intestine and distribution subsequently

occurs via the serum, where it predominately exists bound to several proteins such as

albumin, -microglobulin, and transferrin [Scott BJ et al,1983.].

On the cellular level, 3040% of zinc is localized in the nucleus, 50% in the cytosol and

the remaining part is associated with membranes [Vallen BL et al,1993]. Cellular zinc

underlies an efficient homeostatic control that avoids accumulation of zinc in excess .

The cellular homeostasis of zinc is mediated by two protein families; the zinc-importer

(Zip; Zrt-, Irt-like proteins) family, containing 14 proteins that transport zinc into the

cytosol, and the zinc transporter (ZnT) family, comprising 10 proteins transporting zinc

out of the cytosol [Licthen et al,2009.]. The same transporter families also regulate the

intracellular distribution of zinc into the endoplasmic reticulum, mitochondria, and Golgi.

In addition, many mammalian cell types also contain membrane-bound vesicular

structures, so-called zincosomes. These vesicles sequester high amounts of zinc and

release it upon stimulation, e.g., with growth factors [Haase H et al, 2003].

Finally, metallothioneins (MTs) play a significant role in zinc homeostasis by

complexing up to 20% of intracellular zinc [Taylor KM et al,2008.]. MTs are ubiquitous

proteins, characterized by a low-molecular weight of 67 kDa, high cysteine content, and

their ability to complex metal ions. One MT molecule can bind up to seven zinc ions.

Through different affinities of the metal ion binding sites, it can act as a cellular zinc

buffer over several orders of magnitude [Krezel A et al,2007]. Dynamic regulation of

cellular zinc by MT results from the synthesis of the apo-form thionein (T) in response to

elevated intracellular zinc levels by triggering the metal response element-binding

transcription factor (MTF)-1 [Laity JH et al,2007.]. In addition, oxidation of cysteine

residues can alter the number of metal binding thiols, connecting redox and zinc

metabolism. An in-depth discussion of this complex subject can be found in a recent

review [Maret W et al, 2006].

Zinc Supplementation and Cancer

Whereas several other metals are well-known carcinogens, zinc is not generally

considered to be a causative agent for cancer development. In contrast, displacement of

zinc from zinc-binding structures, e.g., finger structures in DNA repair enzymes, may
http://www.ncbi.nlm.nih.gov/pubmed/8419966http://www.ncbi.nlm.nih.gov/pubmed/8419966http://www.ncbi.nlm.nih.gov/pubmed/8419966


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even be a major mechanism for carcinogenicity of other metals such as cadmium, cobalt,

nickel, and arsenic [Tapiero H et aaal,2007.].

Immunological Effects

Sufficient availability of zinc is of particular importance to the immune system. Thereby,

it plays a key role in multisided cellular and molecular mechanisms . For instance, zinc

influences the lymphocyte response to mitogens and cytokines, serves as a co-factor for

the thymic hormone thymulin, and is involved in leukocyte signal transduction. An

influence of zinc excess on T cell function was observed in several in vitro studies. In cell

culture, very high zinc concentrations (above 100 M) in a serum -free culture medium

stimulate monocytes to secrete pro-inflammatory cytokines, but actually inhibit T cell

functions. In general, T cells have a lower intracellular zinc concentration and are more

susceptible to increasing zinc levels than monocytes. Also, in vitro alloreactivity was

inhibited in the mixed lymphocyte reaction (MLC) after treatment with more than 50 M

zinc. A similar inhibition was observed when the MLC was done ex vivo with cells from

individuals that had been supplemented with 80 mg zinc per day for one week, indicating

that zinc supplementation has the potential to suppress the allogeneic immune response at

relatively low doses.

COPPER

Copper is an essential trace element that is vital to the health of all living things (humans,

plants, animals, and microorganisms). The human body normally contains copper at a

level of about 1.4 to 2.1 mg for each kg of body weight. Copper is distributed widely in

the body and occurs in liver, muscle and bone. Copper is transported in the bloodstream

on a plasma protein called ceruloplasmin. When copper is first absorbed in the gut it is

transported to the liver bound to albumin. Copper metabolism and excretion is controlled

delivery of copper to the liver by ceruloplasmin, where it is excreted in bile.

Daily dietary standards for copper have been set by various health agencies around the

world. Researchers specializing in the fields of microbiology, toxicology, nutrition, and

health risk assessments are working together to define precise copper levels required for

essentiality while avoiding deficient or excess copper intakes.
http://en.wikipedia.org/wiki/Trace_elementhttp://en.wikipedia.org/wiki/Plasma_proteinhttp://en.wikipedia.org/wiki/Ceruloplasminhttp://en.wikipedia.org/wiki/Liverhttp://en.wikipedia.org/wiki/Serum_albuminhttp://en.wikipedia.org/wiki/Bilehttp://en.wikipedia.org/wiki/Microbiologyhttp://en.wikipedia.org/wiki/Toxicologyhttp://en.wikipedia.org/wiki/Nutritionhttp://en.wikipedia.org/wiki/Health_risk_assessmentshttp://en.wikipedia.org/wiki/Health_risk_assessmentshttp://en.wikipedia.org/wiki/Nutritionhttp://en.wikipedia.org/wiki/Toxicologyhttp://en.wikipedia.org/wiki/Microbiologyhttp://en.wikipedia.org/wiki/Bilehttp://en.wikipedia.org/wiki/Serum_albuminhttp://en.wikipedia.org/wiki/Liverhttp://en.wikipedia.org/wiki/Ceruloplasminhttp://en.wikipedia.org/wiki/Plasma_proteinhttp://en.wikipedia.org/wiki/Trace_element


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Copper excess and deficiency

It is believed that zinc and copper compete for absorption in the digestive tract so that a

diet that is excessive in one of these minerals may result in a deficiency in the other. The

RDA for copper in normal healthy adults is 0.9 mg/day. On the other hand, professional

research on the subject recommends 3.0 mg/day. Because of its role in facilitating iron

uptake, copper deficiency can often produce anemia-like symptoms. Conversely, an

accumulation of copper in body tissues are believed to cause the symptoms of Wilson's

disease in humans. Copper deficiency is also associated with neutropenia, bone

abnormalities, hypopigmentation, impaired growth, increased incidence of infections, and

abnormalities in glucose and cholesterol metabolism. Severe deficiency can be found by

testing for low plasma or serum copper levels, low caeruloplasmin, and low red blood

cell superoxide dismutase (SOD) levels. However, these tests are not sensitive to

marginal but not severe copper status. The "cytochrome c oxidase activity of leucocytes

and platelets" is another sign of deficiency, but the results have not been confirmed by

replication.

IRON

Iron is a necessary trace element found in nearly all living organisms. Iron-containing

enzymes and proteins, often containing heme prosthetic groups, participate in many

biological oxidations and in transport. Examples of proteins found in higher organisms

include hemoglobin, cytochrome, and catalase.

Uptake and storage

In cells, iron storage is carefully regulated; "free" iron ions do not exist as such. A major

component of this regulation is the protein transferrin, which binds iron ions absorbed

from the duodenum and carries it in the blood to cells. In animals, plants, and fungi, iron

is often the metal ion incorporated into the heme complex. Heme is an essential

component ofcytochrome proteins, which mediate redox reactions, and of oxygen carrier

proteins such as hemoglobin, myoglobin, and leghemoglobin. Inorganic iron also

contributes to redox reactions in the iron-sulfur clusters of many enzymes, such as

nitrogenase (involved in the synthesis of ammonia from nitrogen and hydrogen) and
http://en.wikipedia.org/wiki/Zinchttp://en.wikipedia.org/wiki/Recommended_Dietary_Allowancehttp://en.wikipedia.org/wiki/Milligramhttp://en.wikipedia.org/wiki/Copper_deficiencyhttp://en.wikipedia.org/wiki/Anemiahttp://en.wikipedia.org/wiki/Wilson%27s_diseasehttp://en.wikipedia.org/wiki/Wilson%27s_diseasehttp://en.wikipedia.org/wiki/Neutropeniahttp://en.wikipedia.org/wiki/Caeruloplasminhttp://en.wikipedia.org/wiki/Superoxide_dismutasehttp://en.wikipedia.org/wiki/Trace_elementhttp://en.wikipedia.org/wiki/Hemehttp://en.wikipedia.org/wiki/Prosthetic_grouphttp://en.wikipedia.org/wiki/Cytochromehttp://en.wikipedia.org/wiki/Catalasehttp://en.wikipedia.org/wiki/Catalasehttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Transferrinhttp://en.wikipedia.org/wiki/Duodenumhttp://en.wikipedia.org/wiki/Bloodstreamhttp://en.wikipedia.org/wiki/Cytochromehttp://en.wikipedia.org/wiki/Redoxhttp://en.wikipedia.org/wiki/Carrier_proteinhttp://en.wikipedia.org/wiki/Carrier_proteinhttp://en.wikipedia.org/wiki/Hemoglobinhttp://en.wikipedia.org/wiki/Myoglobinhttp://en.wikipedia.org/wiki/Leghemoglobinhttp://en.wikipedia.org/wiki/Iron-sulfur_clusterhttp://en.wikipedia.org/wiki/Enzymehttp://en.wikipedia.org/wiki/Nitrogenasehttp://en.wikipedia.org/wiki/Ammoniahttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Nitrogenhttp://en.wikipedia.org/wiki/Ammoniahttp://en.wikipedia.org/wiki/Nitrogenasehttp://en.wikipedia.org/wiki/Enzymehttp://en.wikipedia.org/wiki/Iron-sulfur_clusterhttp://en.wikipedia.org/wiki/Leghemoglobinhttp://en.wikipedia.org/wiki/Myoglobinhttp://en.wikipedia.org/wiki/Hemoglobinhttp://en.wikipedia.org/wiki/Carrier_proteinhttp://en.wikipedia.org/wiki/Carrier_proteinhttp://en.wikipedia.org/wiki/Redoxhttp://en.wikipedia.org/wiki/Cytochromehttp://en.wikipedia.org/wiki/Bloodstreamhttp://en.wikipedia.org/wiki/Duodenumhttp://en.wikipedia.org/wiki/Transferrinhttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Catalasehttp://en.wikipedia.org/wiki/Cytochromehttp://en.wikipedia.org/wiki/Prosthetic_grouphttp://en.wikipedia.org/wiki/Hemehttp://en.wikipedia.org/wiki/Trace_elementhttp://en.wikipedia.org/wiki/Superoxide_dismutasehttp://en.wikipedia.org/wiki/Caeruloplasminhttp://en.wikipedia.org/wiki/Neutropeniahttp://en.wikipedia.org/wiki/Wilson%27s_diseasehttp://en.wikipedia.org/wiki/Wilson%27s_diseasehttp://en.wikipedia.org/wiki/Anemiahttp://en.wikipedia.org/wiki/Copper_deficiencyhttp://en.wikipedia.org/wiki/Milligramhttp://en.wikipedia.org/wiki/Recommended_Dietary_Allowancehttp://en.wikipedia.org/wiki/Zinc


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hydrogenase. Non-heme iron proteins include the enzymes methane monooxygenase

(oxidizes methane to methanol), ribonucleotide reductase (reduces ribose to deoxyribose;

DNA biosynthesis), hemerythrins (oxygen transport and fixation in Marine invertebrates)

and purple acid phosphatase (hydrolysis ofphosphate esters). Iron distribution is heavily

regulated in mammals, partly because iron ions have a high potential for biological

toxicity. Iron acquisition poses a problem for aerobic organisms because ferric iron is

poorly soluble near neutral pH. Thus, bacteria have evolved high-affinity sequestering

agents called siderophores.

GERMANIUM

Germanium has gained popularity in recent years for its reputed ability to improve

immune system function in cancer patients. It is available in the U.S. as a nonprescription

dietary supplement in oral capsules or tablets, and has also been encountered as an

injectable solution. Earlier inorganic forms, notably the citrate-lactate salt, led to a

number of cases of renal dysfunction, hepatic steatosis and peripheral neuropathy in

individuals using it on a chronic basis. Plasma and urine germanium concentrations in

these individuals, several of whom died, were several orders of magnitude greater than

endogenous levels. The more recent organic form, beta-carboxyethylgermanium

sesquioxide (propagermanium), has not exhibited the same spectrum of toxic effects

SILICON

Silicon is contained in plants and also present in animals including humans.. The quantity

in humans is 7 grams being more than all other trace elements together. Nevertheless Si is

not (or hardly) considered as beneficial: there is a lot of scepticism in regular Medicine

because silicon has been considered to be inert in humans. In 1973 the Joint FAO/WHO

Expert Committee on Food Additives says: data on orally administered silica and

silicates appear to substantiate the biological inertness of these compounds.

This negative attitude is surprising because for several hundreds of years extracts of Si

accumulating plants like Equisetum arvense (horsetail) have been used therapeutically for

aging disorders, Alzheimer's disease, atherosclerosis, brittle hair, fractures, fragile nails,

back pain, osteoporosis, skin disorders, tendinitis, improved wound healing and wrinkles.
http://en.wikipedia.org/wiki/Hydrogenasehttp://en.wikipedia.org/wiki/Enzymeshttp://en.wikipedia.org/wiki/Methane_monooxygenasehttp://en.wikipedia.org/wiki/Methanehttp://en.wikipedia.org/wiki/Methanolhttp://en.wikipedia.org/wiki/Ribonucleotide_reductasehttp://en.wikipedia.org/wiki/Ribosehttp://en.wikipedia.org/wiki/Deoxyribosehttp://en.wikipedia.org/wiki/DNA_replicationhttp://en.wikipedia.org/wiki/Hemerythrinhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Marine_invertebrateshttp://en.wikipedia.org/wiki/Acid_phosphatasehttp://en.wikipedia.org/wiki/Hydrolysishttp://en.wikipedia.org/wiki/Phosphatehttp://en.wikipedia.org/wiki/Esterhttp://en.wikipedia.org/wiki/Mammalhttp://en.wiktionary.org/wiki/sequesterhttp://en.wikipedia.org/wiki/Siderophorehttp://en.wikipedia.org/wiki/Propagermaniumhttp://en.wikipedia.org/wiki/Propagermaniumhttp://en.wikipedia.org/wiki/Siderophorehttp://en.wiktionary.org/wiki/sequesterhttp://en.wikipedia.org/wiki/Mammalhttp://en.wikipedia.org/wiki/Esterhttp://en.wikipedia.org/wiki/Phosphatehttp://en.wikipedia.org/wiki/Hydrolysishttp://en.wikipedia.org/wiki/Acid_phosphatasehttp://en.wikipedia.org/wiki/Marine_invertebrateshttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Hemerythrinhttp://en.wikipedia.org/wiki/DNA_replicationhttp://en.wikipedia.org/wiki/Deoxyribosehttp://en.wikipedia.org/wiki/Ribosehttp://en.wikipedia.org/wiki/Ribonucleotide_reductasehttp://en.wikipedia.org/wiki/Methanolhttp://en.wikipedia.org/wiki/Methanehttp://en.wikipedia.org/wiki/Methane_monooxygenasehttp://en.wikipedia.org/wiki/Enzymeshttp://en.wikipedia.org/wiki/Hydrogenase


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On the other hand there is a lack on sufficient data on the metabolism of silicon in

animals and humans. The absorption and bioavailability of silicon of the different silicon

sources (silicates, metasilicates, etc.) is hardly known. There are neither standardised

methods nor assays for assessing the silicon status in humans and animals.

1 . Effects of silicon on tissues, organs and diseases

Bone and cartilage

In 1972, Carlisle showed that a Si deficient diet in chickens induces skeletal deformities

and joint abnormalities. Also in 1972, Schwartz published the same results in rats:

deformities of the skull and peripheral bones, characterized by poorly formed joints,

defective endochondral bone growth and reduced contents of articular cartilage,

hexosamine, collagen and water. The concentrations of minerals like calcium,

magnesium, zinc and manganese were also to low in the femur and vertebrae due to the

diet only Si deficient.

Both studies mark the beginning of the recognition of the importance of silicon as an

beneficial even essential trace element that plays an important biological role in the

processes by which connective tissue, bone, cartilage and skin are formed. A growing

number of publications appear on the effects of Si on bone and cartilage as well in men as

in animals: Schiano a.o. (1979) studied the activity of a soluble salt (drinkable and

injectable) of Si on the evolution of the trabecular bone volume (TBV) in men. They note

a significant increase in the TBV compared to controls.

Eisinger e.a. (1993) showed in a prospective study that Si induced a significant (P < 0.05)

increase in femoral bone mineral density in osteoporotic women compared to controls.

Rico et al. showed in 2000 the effects of Si supplement on preventing bone mass loss

induced by ovariectomy in rats. They proved that Si has an inhibitory effect on bone mass

loss as well as the stimulatory effect on bone formation, so Si may have a potential

therapeutic application in the treatment of involutive osteoporosis. Calomme et al.

showed the positive effects of orthosilicic acid on bone density in chicks (2002) and on

the bone density in ovariectomized rats (2004)..

Skin, hair and nails

The effects of Si on hair, skin and nails appear in regular literature: Lassus performed an

open study in 1993 with oral Si (colloidal silicic acid) during 3 months. He found a


26/41

(statistically significant) improvement in the thickness and turgor of the skin, wrinkles

and condition of the hair and nails. Barel et al. investigated the Si supplementation on

skin, nails and hair in a double-blind, placebo controlled study. The (extra) Si had a

significant positive effect on skin surface and mechanical properties, and on brittleness of

hair and nails. The application of topical silicone gel is shown to be efficacious, both in

the prevention and in the treatment of hypertrophic scar.

Cardiovascular system / Atherosclerosis

Animal studies f.e. in rabbits (Loeper 1979) indicate that Si can reduce the formation of

atheromatous plaques. There is a low incidence of atherosclerosis in less developed

countries where foods are not heavily processed before consumption and the diet has a

higher Si content. In western diets the Si content is much lower and atherosclerosis is

much higher. Moreover Si intakes decrease significantly with age (Jugdaohsingh, et al.,

2002) suggesting that high Si intake is a factor in (partial) preventing atherosclerosis

(Schwartz, 1977). Other observations supporting the concept that sufficient silicon intake

is important for healthy blood vessels is that of an inverse relationship between the

concentration of silicic acid in drinking water and the prevalence of cardiovascular

disease in Finland (Schwartz 1977). Underlying mechanism: Silicon is essential for the

strength and integrity of the tunica intima, the inner membrane of arteries.

Alzheimer's disease

Some evidence suggests that aluminum may increase the risk of developing Alzheimer's

disease. Si has been found to significantly reduce the absorption of aluminum by the

body, and researchers hypothesize that dietary Si may therefore reduce the risk of

developing aluminum induced Alzheimer's disease. The protective role of silicon against

aluminum was also confirmed in a French population study of elderly subjects: high

levels of aluminum in drinking water had a deleterious effect upon cognitive function

when the silicon concentration was low, but when the concentration of silicon was high,

exposure to aluminum appeared less likely to impair cognitive function.


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MECHANISM OF TOXICITY OF SOME SELECTED METALS

LEAD

Lead ranks second among the prioritized hazardous substances issued by the U.S.

ATSDR[Agency for Toxic Substances and Disease Registry] in 1999. The noxious

effects of this metal have long been well known, especially as regards acute forms of

poisoning . However, as for many other contaminants, the threshold level of safety has

been drastically lowered recently. Until approximately 30years ago, chronic lead

poisoning was defined by blood lead levels above 80(gr/dl),while today a lead level of

30(gr/dl) in the blood is considered excessive and level at above 10(gr/dl) (0.1ppm) are

considered potentially harmful, particularly in children. Once absorbed by the body,

mainly through breathing and feeding, lead is not metabolized, but mostly expelled. The

remaining portion (about 20%) settles into the tissues and notably:

In the blood, where it is carried almost exclusively by the erythrocytes In mineral tissues (bone and teeth), where it deposits In soft tissues (kidney, bone marrow, liver and brain)

The presence of lead in the blood stream(inside the red blood cells and mostly linked to

haemoglobin) provokes anaemia Through the blood, lead reaches all other tissues.

Because of its capacity to mimic calcium. Lead is stored in the bones and becomes a

stable bone component, particularly in the case insufficient calcium intake. This lead

deposits may be mobilized and return into the blood stream under particular state of

physiological stress (pregnancy, breast-feeding, diseases ), but also as a consequence of

greater calcium intake in the diet. This stable presence of lead in bones make recoveryfrom lead poisoning extremely slow, even when toxic agent has been completely

elimated.

Lead can damage practically all tissues, particularly the kidneys and the immune system.

The most deceptive and dangerous form of lead poisoning is that affecting the nervous

system. In adults, lead damage mainly causes peripheral neuropathy, which is

characterized predominantly by demyelination of the nerve fibres. Intense exposure to


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lead to high level (from100 to 200 gr/dl) causes encephalopathy, with the following

symptoms: vertigo, insomnia, migraine, irritability and convulsion, seizure and coma.

Lower level of the metal gives rise to lead induced neuropathy, which mainly affects the

developing brain and provokes behavioural problem and cognitive impairment.

Epidemiological studies have shown a strong correlation between lead levels in blood and

bones and poor performance in attitude tests(IQ or psychometric tests). A similar

correlation has also been found in behavioural studies carried out on animals that had

been exposed lead immediately after birth. The learning process is based on the creation

and remodeling of synapses and the toxic effect of lead on this process suggests that this

metal specifically damages the synaptic function.

Action Mechanism

Lead toxicity is largely due to its capacity to mimic calcium and substitute it in many of

the fundermental cellular processes that depend on calcium. Lead can cross the cell

membrane in several ways which are not well understood. Lead transport through the

erythrocyte membrane is mediated by an anion exchanger in one direction and by the Ca-

ATPase pump in the other direction. In other tissues, lead permeates the cell membrane

through voltage-dependent or other types of calcium channels.

Once it has penetrate the cytoplasm, lead continues its destructive mimicking action by

occupying the calcium binding sites on numerous calcium-dependent proteins. Lead bind

to calmodulin, a protein which in the synaptic terminal acts as a sensor of free calcium

concentration and as mediator of neurotransmitter release. Furthermore, it alters the

functioning of the enzyme protein kinase C, a virtually ubiquitous protein which is of

crucial importance in numerous physiological functions. Kinase C is normally activated

by modulator outside the cell (hormones, neurotransmitters, etc) through an enzyme chain

and in a calcium-dependent manner. Beside many other functions, the activated kinase

directly affect the expression of the immediate response gene(IERG). Lead has high

affinity for the sites which are typical calcium-binding site in this protein; picomolar

doses can take the place of micromolar calcium doses. In model cell system, it has been

demonstrated that lead can stimulate gene expression through a mechanism mediated by

protein kinase C and it is postulated that this effect may correlate with alteration in

synaptic functioning.


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Other toxic effects include:

Inhibition of heme biosynthesis. Heme is the essential structural component ofhemoglobin, myoglobin andcytochromes.

Binds to sulfhydryl groups (-SH groups) of proteins.

Fig 3 : Mechanism of lead toxicity.

Source :Theodore et al, 2002.


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Cadmium

Cadmium is potent poison, which causes different types of damage , including cell death

or increase in cell proliferation. Cadmium is a metal which is widely used in industry in

alloys, in plating, in batteries and in the pigments used in inks, paints, plastic, rubber and

enamel. It is an extremely toxic substance and the major hazard is from inhalation of

cadmium metal or cadmium oxide. Although it is present in food, significant oral

ingestion is rare and absorption from the gut is poor (58%). However, various dietary

and other factors may enhance absorption from the gastrointestinal tract. In contrast, up to

40% of an inhaled dose may be absorbed and hence its presence in cigarettes is a

significant source of exposure. Cadmium is bound to proteins and red blood cells in blood

and transported in this form, but 5075% of the body burden is located in the liver and

kidneys. The half-life of cadmium in the body is between 7 and 30 years and it is

excreted through the kidneys, particularly after they become damaged.

Cadium has many toxic effects, primarily causing kidney damage, as a result of chronic

exposure, and testicular damage after acute exposure, although the latter does not seem

to be a common feature in humans after occupational exposure to the metal. It is also

hepatotoxic and affects vascular tissue and bone. After acute inhalation exposure, lung

irritation and damage may occur along with other symptoms such as diarrhea and

malaise. Chronic inhalation exposure can result in progressive fibrosis of the lower

airways leading to emphysema. This results from necrosis of alveolar macrophages and

hence release of degradative enzymes which damage the basement membranes of the

alveolus. These lung lesions may occur before kidney damage is observed. Cadmium can

also cause disorders of calcium metabolism and the subsequent loss of calcium from the

body leads to osteomalacia and brittle bones. In Japan this became known as Itai-Itai

(Ouch-Ouch!) disease when it occurred in women eating rice contaminated with

cadmium. The raised urinary levels of proline and hydroxyproline associated with

chronic cadmium toxicity may be due to this damage to the bones.


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Kidney damage is a delayed effect even after single doses, being due to the

accumulation of cadmium in the kidney, as a complex with the protein metallothionein.

Metallothionein is a low molecular weight protein (6500 Da) containing about 30%

cysteine, which is involved with the transport of metals, such as zinc, within the body.

Due to its chemical similarity to zinc, cadmium exposure induces the production of this

protein and 8090% of cadmium is bound to it in vivo, probably through SH-groups on

the protein. Thus, exposure to repeated small doses of cadmium will prevent the toxicity

of large acute doses by increasing the amount ofmetallothionein available. The protein

is thus serving a protective function. The cadmium-metallothionein complex is

synthesized in the liver and transported to the kidney, filtered through the glomerulus and

is reabsorbed by the proximal tubular cells, possibly by endocytosis. Within these cells

the complex is taken up into lysosomes and degraded by proteases to release cadmium

which may damage the cells or recombine with more metallothionein.

Mercury

Mercury can exist in three forms, elemental, inorganic and organic, and all are toxic.

However, the toxicity of the three forms of mercury are different, mainly as a result of

differences in distribution. Some of these toxic properties have been known for centuries.Elemental mercury (Hg) may be absorbed by biological systems as a vapour. Despite

being a liquid metal, mercury readily vaporizes at room temperature and in this form

constitutes a particular hazard to those who use scientific instruments containing it for

example. Elemental mercury vapour is relatively lipid soluble and is readily absorbed

from the lungs following inhalation and is oxidized in the red blood cells to Hg2+.

Elemental mercury may also be transported in red blood cells to other tissues such as the

CNS. Elemental mercury readily passes across the blood-brain barrier into the CNS and

also into the foetus. The metallic compound is only poorly absorbed from the

gastrointestinal tract, however. Inorganic mercury, existing as monovalent (mercurous)

or divalent (mercuric) ions is relatively poorly absorbed from the gastrointestinal tract

(7% in humans). After absorption inorganic mercury accumulates in the kidney. Organic

mercury is the most readily absorbed (9095% from the gastrointestinal tract), and after

absorption distributes especially to the brain, particularly the posterior cortex. All the

forms of mercury will cross the placenta and gain access to the foetus, although elemental


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mercury and organic mercury show greater uptake. The concentrations in certain foetal

tissues, such as red blood cells, are greater than in maternal tissue. Mercury is eliminated

from the body in the urine and faeces with the latter being the major route. Thus, with

methyl mercury 90% is excreted into the faeces. Methyl mercury is secreted into the bile

as a cysteine conjugate and undergoes extensive enterohepatic recirculation. The half-

life of mercury is long but there are two phases, the first being around 2 days, then the

terminal phase which is around 20 days. However the half-life will depend on the form of

mercury. Thus methyl mercury has a half-life of about 70 days whereas for inorganic

mercury this is about 40 days.

Toxic effects

Elemental mercury vapourAlthough there may be toxic effects to the respiratory system from the inhalation of

mercury vapour, the major toxic effect is to the CNS. This is especially true after chronic

exposure. There are a variety of symptoms such as muscle tremors, personality changes,

delirium, hallucination and gingivitis.

Inorganic mercury

Mercuric chloride and other mercuric salts will, when ingested orally, cause immediate

acute damage to the gastrointestinal tract. This may be manifested as bloody diarrhoea,

ulceration and necrosis of the tract. After 24 h renal failure occurs which results from

necrosis of the pars recta region of the proximal tubular epithelial cells. The epithelial

cells show damage to the plasma membrane, endoplasmic reticulum, mitochondria and

effects on the nucleus. The result of this damage is excretion of glucose (glycosuria),

amino acids (aminoaciduria), appearance of proteins in the urine (proteinuria), and

changes in various metabolites excreted into urine.

Organic mercury

Mercury in this form, such as methyl mercury, is extremely toxic, mainly affecting the

CNS. However, some organomercury compounds such as phenyl and methoxyethyl

mercury cause similar toxic effects to inorganicmercury. There have been a number of

instances in which human exposure to methylmercury has occurred, and consequently

data is available on the toxic effects to man as well as experimental animals. Methyl


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mercury was responsible for the poisoning which occurred in Japan, known as Minamata

disease. This resulted from industrial effluent containing inorganic mercury

contaminating the water of Minamata Bay in Japan. The microorganisms in the sediments

at the bottom of the bay biotransformed the inorganic mercury ions into methyl and

dimethyl mercury. As this form of mercury is lipid soluble it was able to enter the food

chain and so become concentrated in fish as a result of their eating small organisms

which had absorbed the methyl mercury. The local population who consumed the fish

therefore became contaminated with methyl mercury. Another episode occurred in Iraq

when seed grain treated with a methyl mercury fungicide was used to make bread. Over

6000 people were recorded as exposed and more than 500 died. The major features of

methyl mercury poisoning are paresthesia, ataxia, dysarthria and deafness..

Mechanism

Mercury is a reactive element and its toxicity is probably due to interaction with proteins.

Mercury has a particular affinity for sulphydryl groups in proteins and consequently is an

inhibitor of various enzymes such as membrane ATPase, which are sulphydryl

dependent. It can also react with amino, phosphoryl and carboxyl groups. Brain pyruvate

metabolism is known to be inhibited by mercury, as well as lactate dehydrogenase and

fatty acid synthetase. The accumulation of mercury in lysosomes increases the activity of

lysomal acid phosphatase which may be a cause of toxicity as lysosomal damage releases

various hydrolytic enzymes into the cell, which can then cause cellular damage. Mercury

accumulates in the kidney and is believed to cause uncoupling of oxidative

phsophorylation in the mitochondria of the kidney cells. Thus, a number of mitochondrial

enzymes are inhibited by Hg2+

. These effects on the mitochondria will lead to a reduction

of respiratory control in the renal cells and their functions such as solute reabsorption,

will be compromised

Chromium

Chromium (IV) has long been recognized as a toxin in plant systems and as a carcinogen

in human and mammalian systems. The actual mutagenic or toxic species of chromium is

one or more of the reactive intermediate produced in the reduction of Cr(IV) to Cr(III).

Glutathione is suspected to be a reductant here due to its ability to produce long-lived

Cr(V/IV) intermediate during the reduction of chromium(IV). GSH-Cr interaction in


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plant have been fairly well elucidated (Shanker et al, 2004). Dichromate reacts with

glutathione at the sulfhydryl group forming an unstable glutathione-Cr03 complex. The

halliwel Asada pathway is the key pathway whereby Cr toxicity or tolerance is mediated.

The high content of dihydro-ascorbate (DHA) in combination with an absence of active

scavenging of free radicals and blockage of normal cell cycle progression by DHA is one

of the main mechanism of chromium induced toxicity in plant (Shanker et al, 2004).

Cr(VI) can function as a hill reagent and can inhibit electron transport both in the

photosynthetic and mitochondrial apparatus thus accounting for reduced NADPH pool.

The critical balance between the available NADPH pool and ROS production by

chromium would decide the redox status of a cell in both plants an animals. Chromium-

DNA interaction is one of the well explained mechanism of action of Cr in apoptosis and

carcinogenesis. Chromium associate with both DNA bases and the phosphodiester

backbone and the binding occur through both covalent binding and electrostatic

interactions. The base specific binding of Chromium has revealed a genera, but not

absolute , preference towards the formation of Cr(III) guanine DNA adducts and

polyriboguanylic acid (poly(G)) in the case of RNA(Obrien et al,2003).

Cr-DNA crosslinks (Cr-DPCs) have been reported to extensively developed respectively

between DNA and non histone proteins and RNA and cytoplasmic protiens in many

animal system. (Reem et al,2007). Cr(VI)-containing compounds are well known

carcinogenic compounds. Evidence also have it that chromosomal

abnormalities(micronuclei) and genomic instability are possibly involved in the induction

of cancer by Cr(VI) (Wise et al, 2008). DNA interstand crosslinks(ICLs) are caused by

Cr interacting with reaction centers on the complementary strands of DNA. A notion that

has received much attention is that intracellular Cr(VI) mediate a fenton-like reaction

mediating ROS production which are responsible for nearly all the toxicity and

genotoxicity caused by Cr(VI) (Shanker et al, 2005)


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Conclusion

According to UNEPA(United Nation Environmental Programme Agency) about 5.3

million tones of electronic waste was generated worldwide in year 2009 and only 13%

was recycled, and most of these recycling were done in the developed countries. Due to

poor regulations on e-waste recycling in the developing countries, a lot of methods toretrieve certain metals from electronics and disposing e-waste are polluting the

environment. These toxic materials in the e-waste when disposed indiscriminately or

even used as landfills, can leach into the underground water and accumulates in sea foods

and plants. This may cause health hazard ranging from tissues or organs damage to

chromosomal abnormalities, DNA damage, cancer and eventually death.

Developed countries and places that are not home to e-waste landfills and pollution are

not completely excluded from the effects of e-waste. Pollutants can seep into the oceans

or travel in the air, thus making e-waste not to be limited by boundaries.

There fore individuals, NGOs and the government together to put up a functioning

regulations and well structured recycling programme that will help ,if not to stop

completely, but to reduce to minimal the challenges of e-waste.


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