Transcript Slide 1

Heavy Metals
“The term heavy metal refers to any metallic chemical
element that has a relatively high density and is toxic or
poisonous at low concentrations.”
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Mercury (Hg)
Arsenic
(As)
Chromium (Cr)
Thallium (Tl)
Lead
(Pb)
Cadmium (Cd)
Characteristics
 Natural components of the Earth's crust
 Can’t be degraded or destroyed
 Essential to maintain the metabolism of the human body
 Higher concentrations lead to poisoning
 Heavy metals are dangerous because they tend to
bioaccumulate.
Effect of Lead on the Environment
 Lead is a naturally occurring
bluish-gray metal found in small
amounts in the earth's crust.
 Lead is a chemical element with
the atomic number 82
 Extremely poisonous to humans!!
SOURCES
Natural
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Weathering and erosion
Volcanic eruption
Sea spray
Plants
Forest fires
Man-made
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Lead piping system
Leaded gasoline
lead acid batteries
Municipal and Industrial solid waste
and waste water
Cosmetics
Lead based paints
Tanneries
Lead particles from vehicular
emission
Jewelry
Lead-glazed pottery
Lead Exposure in the environment
 220 million pounds
car exhaust
 3 billion pounds
smoking chimneys of manufacturing plants
 4 million tons
earth’s crust each year
In air
 Industrial emissions, smelters and refineries,
weathering and erosion, volcanic eruption, forest fires
etc.
 Atmospheric concentration had been known to range
between
0.3-1.1 ug/m3 in urban areas
0.5-0.3 ug/m3 in rural areas
In Food
 Airborne lead falls onto crops or soil and is absorbed
by plants.
 Lead solder used in making cans can also
contaminate food.
 Infants can also absorb lead from their mothers'
bodies through breast milk.
 Gardens grown in lead-contaminated soils may
contain lead root vegetables.
In Dust and soil
 Lead in soil can come from the air or from erosion of lead-bearing
rocks, and may be carried indoors as dust.
 Lead dust can also come from within the home, especially older homes
that used lead-based paints or lead solder.
In Drinking Water
 Lead can enter the water supply from lead solder in plumbing, lead
service connections or lead pipes in your home. Lead levels in tap water
increase as water stands in pipes.
 Drinking fountains may have higher levels of lead than water from
nearby taps, because the water usually sits for a longer time.
How does lead get in your body?
 Breathing (inhalation)
 Eating/drinking (ingestion)
 Skin contact (dermal contact)
Effects of Lead Pollution to Human
Health
 Dioscorides, a Greek physician who lived in the first century A.D., wrote
that lead makes the mind "give way".
 Lead poisoning was among the first known and most widely studied work
and environmental hazards Lead was used extensively in Roman
aqueducts from about 500 B.C. to 300 A.D.
 Ancient Roman society was degenerated due to lead poisoning from
plumbing, which induces schizophrenia,
Short-term lead poisoning affects
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Nausea
Abdominal pain
Insomnia
Lethargy
Hyperactivity
Headache
Seizures
Long term effects of lead poisoning
 Small increases in blood
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pressure
Anemia
Liver Damage
Kidney Damage
Gastritis
Mental retardation
Learning disabilities
Decreased growth
Cause osteoporosis
Severe damage to the brain
Reduced IQ level
Effect of lead on children
 Lead poisoning is now
recognized internationally, as
one of the greatest
environmental health risks
facing children today.
 Since their brain and nervous
system are still developing they
are more easily damaged by
lead.
 Children’s bodies will absorb
50% of lead while adults will
only absorb 10%
In other animals
 Sources of lead exposure in pets can be the same as those that
present health threats to humans sharing the environment, such
as paint and blinds, and there is sometimes lead in toys made for
pets.
 Farm animals such as cows and horses as well as pet animals are
also susceptible to the effects of lead toxicity.
 Animals experience many of the same effects of lead exposure as
humans do, such as abdominal pain, peripheral neuropathy, and
behavioral changes such as increased aggression
How to reduce lead exposure
 Wash all food before cooking
 Make sure all paint is in good condition.
 Wet-clean all surfaces, especially window sills, at
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least every week.
Wash children’s hands frequently.
Renovate house to get rid of old lead pipes and
paint
Plant grass on exposed areas of soil
Run hot water 3-5 seconds to clear the lead out
of older pipes
Dispose of lead-glazed pots correctly
Effect of Cadmium on the Environment
 Cadmium is a naturally occurring minor element,
 Metallic components in the earth’s crust and oceans
 First discovered in Germany in 1817 as a by-product of the zinc refining
process
Sources of cadmium
 Natural
• Erosion
• Abrasion of rocks and soils
• Forest fires
• Volcanic eruptions
Man-made
• Nickel-Cadmium Batteries
• Phosphorous fertilizers containing cadmium
• Cadmium pigments
• Burning of fossil fuel
• Cement industry
• Release during combustion
• Smelter or power plant
Cadmium in the environment
Cadmium levels in the environment reached a peak in the 1960's. Since
then, these levels have been constantly decreasing due to improved
technology for the production, use and disposal of cadmium and
cadmium-containing products
Cadmium in Air
 Cadmium in ambient air
 Cadmium air levels in occupational exposure situations
 Cadmium in air from the smoking of tobacco
Whereas cadmium from occupational environments and cadmium from
cigarette smoke are transferred directly to humans.
Cadmium in ambient air is generally deposited
waters or soils
plants and animals
human body through the food chain.
Cadmium Levels in Soils
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Earth's crust
Igneous and metamorphic rocks
Sedimentary rocks
Fossil fuels contain
Phosphate fertilizers contain
0.1-0.5 ppm
0.02-0.2 ppm
0.1-25 ppm
0.5-1.5 ppm
10-200 ppm
In food
 Leafy vegetables such as lettuce and
spinach and certain staples such as potatoes
and grain foods
ppb
 Meat and fish normally contain lower
ppb
 Animal offal such as kidney and liver
ppb
30-150
5-40
1,000
In water
 Any cadmium in sewage is there because it has somehow entered the
sewerage system via drains in homes, or business premises, or from
drains in the streets and roads.
How does Cadmium get in
your body?
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Food you eat
Water you drink
Particles you breathe in.
Very little cadmium enters through your skin.
If you do not eat foods that contain enough iron or other nutrients, you
are likely to take up more cadmium from your food than usual.
Effects of Cadmium Pollution to Human
Health
 Flu like symptoms including chills, fever, and muscle ache
 Tracheo-bronchitis
 pulmonary edema.
 Osteomalacia
Bones become soft
 Osteoporosis
Lose bone mineral density
 Anosmia
lose their sense of smell
 The kidneys lose their function to remove acids from the blood in
proximal renal tubular dysfunction.
 Hypophosphatemia
Low phosphate levels in the blood (causing muscle weakness and sometimes
coma)
 Hyperchloremia
Increased levels of chloride in the blood (The kidneys can also shrink up to 30%.)
In other organisms
 Soils that are acidified enhance the cadmium uptake by plants.
This is a potential danger to the animals that are dependent
upon the plants for survival.
 Cadmium can accumulate in their bodies, especially when they
eat multiple plants. Cows may have large amounts of cadmium
in their kidneys due to this.
 Earthworms and other essential soil organisms are extremely
susceptive to cadmium poisoning.
 In aquatic ecosystems cadmium can bio accumulate in mussels,
oysters, shrimps, lobsters and fish. Animals eating or drinking
cadmium sometimes get high blood-pressures, liver disease and
nerve or brain damage.
How to reduce Cadmium exposure
 Lucky people who are blessed with abundant minerals.
 Although cadmium alters the function of zinc, zinc can also neutralize
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or antidote it.
High levels of calcium can also partially protect against cadmium
uptake, and accumulation in the liver and kidney.
Taking supplemental doses of copper, iron, zinc, and selenium can
also lessen its effect.
A high protein diet reduces the retention of cadmium.
As vitamin C is a natural chelator, it also helps curb its adverse effects.
Situation in Pakistan
 In the formal sector of Pakistan, the leather industry plays an
important role in the economy of a country.
 More than 750 tanneries are unevenly distributed among the four
provinces.
 The effluents from the tanning unit are discharged indiscriminately
into natural water bodies or open land, resulting in contamination of
the surface and ground waters as well as the soil flora and fauna.
 Most adverse of all, the tannery effluents are polluting the Kabul River
to which they are directly or indirectly discharge thus rendering its
water unfit for irrigation.
Current actions and strategies and future plans for preventing
and controlling releases and limiting use and exposures,
including waste management practices
Pakistan Environmental Protection agency (PEPA) at federal level and
provincial EPAs level are enforcing the following acts and rules the
matters relating to collection, transportation, storage, handling,
treatment disposal of hazardous waste including lead and cadmium
and their compounds: Pakistan Environmental Protection Act, 1997
 National Environmental Quality standard (Self-Monitoring and
Reporting by Industries) Rules, 2001
 Environmental Tribunal rules, 1999
 Hazardous Substances Rules, 2003
In future we shall work on: Exact National inventory of Lead and Cadmium uses and release
 Documentation of realistic statistic about Lead and Cadmium
 Identification of the areas severely affected by Lead and Cadmium
pollution
 Designing of safe Lead and Cadmium disposal protocol and
methodologies
 Public awareness programmes of lead and cadmium exposure
 Enforce the local industries to adopt Lead and Cadmium free
alternative chemical processes