electronic waste components
TRANSCRIPT
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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
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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
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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
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(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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