The term heavy metal refers to any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations. Heavy metals are Globally distributed pollutants

1. Heavy metal Contamination
of Global Environment
Presented by
Dr. B. Victor., Ph. D
Email : bonfiliusvictor@gmail.com
Blog: bonvictor.blogspot.com

2. Environmental disasters –
Heavy metal contamination
1932-1952 Minamata
Sewage containing mercury is released by Chisso's chemicals works
into Minimata Bay in Japan. The mercury accumulates in sea foods.
In 1952, the consumption of fish polluted with mercury, caused nearly
1000 fatalities.
1986-11-01 Sandoz
Water used to extinguish a major fire carries fungicide containing
mercury into the Upper Rhine. Fish are killed over a stretch of 100
km.
1998-04 Disaster at Spanish nature reserve
Toxic metals in water from a burst dam of a mine waste containing
sulphur, lead, copper, zinc and cadmium flow down the Rio
Guadimar in southern Spain. Spanish nature reserve was
permanently damaged after this environmental disaster.

3.  Definition, kinds and physical
properties
 Bioactivity and target organ
toxicity
Presentation  Sources and toxicologic
out line properties
 Environmental fate of metals
 Toxicologic diseases
 Mercury, Cadmium, lead,
chromium, arsenic, cobalt, and
zinc contamination – sources,
fate and human health effects.
 Conclusion

4.  The term heavy metal refers to
any metallic chemical element
that has a relatively high
density and is toxic or
What is a poisonous at low
heavy metal ? concentrations.
 Heavy metals are
conventionally defined as
elements with metallic
properties and an atomic
number >20.
 The most common heavy metal
contaminants are Cd, Cr, Cu,
Hg, Pb, and Zn.

5. Physical properties of metals
Good
conductors
of heat and
High density electricity Non-
(heavy for
degradable
their size)
Malleable :
High
melting hammered
point into thin
sheets
Physical Ductile:
Lustre drawn out into
shininess Properties thin wires
of metals

6. Kinds of metals
• lithium (Li), sodium (Na), potassium
Alkali metals (K), rubidium (Rb), caesium (Cs).
Alkaline earth • beryllium (Be) magnesium (mg),
calcium (Ca), strontium (Sr), barium
metals (Ba) and radium (Ra).
• boron, silicon, germanium, arsenic,
Metalloids antimony, tellurium, and polonium
• platinum, silver and gold. copper (Cu),
nickel (Ni), chromium (Cr) and iron
Heavy metals (Fe) cadmium (Cd), lead (Pb), silver
(Ag) and mercury (Hg)

7. Heavy metals
Macro-nutrient • cobalt (Co), copper (Cu)
elements • zinc (Zn) and iron (Fe).
Micronutrient • copper (Cu), nickel (Ni),
elements • chromium (Cr) and iron (Fe)
Highly toxic • cadmium (Cd), lead (Pb),
elements • silver (Ag) and mercury (Hg)
Precious
• platinum, silver and gold
elements

8. Definition
Heavy metal
• Refers to any metallic
chemical element that has a
high specific gravity and
high relative atomic mass.

9. Metals
• Iron, zinc, copper,
chromium, cobalt
Essential • Molybdenum,
selenium
• Silicon, manganese
beneficial • Nickel, boron,
vanadium
• Mercury,cadmium,
Detrimental • lead
• Arsenic, chromium

10. Distinguishing properties of metals
Conservative
Pollutants : Chemical
Effectively time bombs
permanent
Globally
Immutable
distributed
pollutants
pollutants
Heavy
metals

11. Biological activity of metals
Inhibit enzymes
Inhibit synthesis of proteins
Cross membranes by
passive
diffusion/pinocytosis
Target /critical organ for
most metals-kidney

12. Target organ toxicity of metals
Zinc blood hemotoxicity
Arsenic liver hepatotoxicity
Mercury
brain neurotoxicity
Lead
cadmium Kidney
lungs
Nephrotoxicity
pulmonotoxicity

13. Sources of heavy metal pollutants
Mining
Agriculture
Smelting
& forestry
Sources
Fossil fuel Metallurgical
combustion industries
Waste
Corrosion
disposal

14. Toxicological properties of heavy metals
Persistence-long Acute Toxicity-
Soil residence
residual and half plants, animals,
time ->1000 years
life microorganisms
,
Bioaccumulation
Chronic and sub-
and
lethal effects at Synergistic effects
biomagnification-
low conc.
thro’ food chain
Teratogenic and
carcinogenic
properties

15. Fate of heavy metals
Anthropogenic and Industrial activities
Waste metal pollutants
(Volatilization, Leaching)
Environment-
ecological effects
Human system-
exposure via food intake, water consumption, ingestion, dermal
contact, inhalation.
Human health effects

16. Fate of metals in aquatic environment
more soluble
precipitate in
at high
hard water.
temperature.
Benthic
organisms
accumulate soluble in
thro. acidic water
Food chain
aquatic Insoluble
organisms take metals
up from water
or sediments deposit in the
via eating or river
respiration sediments

17. Toxic diseases of heavy metals
Aluminium has been
associated with Arsenic exposure can Cadmium exposure
Alzheimer's and cause cancer, produces kidney
Parkinson's disease, abdominal pain, and damage
senility, and presenile black foot disease. and hypertension
dementia.
Lead and mercury may
cause joint diseases
Nickel can cause Chromium can cause
and ailments of the
damage to lung, liver lung damage and
kidneys, circulatory
and kidney. cancer.
system, and nervous
system

18. Mercury contamination
All forms of mercury are
poisonous
Mercury is persistent and cycles
globally
Continues to be widely used
Can be toxic to CNS, lungs and
kidneys

19. Hg as Toxic contaminant
Most Potent
Oldest poison
neurotoxicant
Developmental
toxicant
fetotoxic

20. Sources of mercury contamination
Anthropogenic
Natural sources
inadvertent sources
 Volcanic eruptions  Mercury mining,
smelting and use.
 Rock weathering
 Burning fossil fuels
 Natural fires  Coal-fired power
plants
Anthropogenic intentional  Municipal / medical
sources waste incineration
• Folk medicines  Cement production
• Cosmetics  Chlorine-alkali
• Dental amalgams production
• Vaccines

21. History of mercury poisonings
Minamata Bay, Japan
 In the 1950’s, large amounts of organic mercury were dumped
into Minamata Bay in Japan.
 Mercury-contaminated fish were consumed by pregnant
women.
 many children that were born from these women had severe
nerve damage.
 later referred as Fetal Minamata Disease.
Iraq
 children born to mothers who consumed grain contaminated
with organic mercury, the effects showed the children walking
at a later age than non-exposed children.
Faroe Islands
 Mercury exposure was caused by contaminated whale meat.
 Children born to mothers with high body levels of mercury
scored lower on brain function tests than mothers with low
body levels.

22. Forms of mercury
• ‘Quick silver’,
natural
Elemental
mercury
element,
• Silver white,
odorless liquid
• Mer-curic /
Inorganic curous
mercury chloride
salts
• Mercury
cyanide
Organic
• Methyl/ ethyl
mercury mercury
compounds
• phenyl mercury

23.  The most dangerous form of
Methyl mercury.
mercury  Hg bio-transformed in
sediments into methyl mercury
by aquatic microbes.
 Bio-accumulate thro’ aquatic
food chain in larger predatory
fishes-tuna, mackerel, shark,
grouper
 Bio-persistent, lipophilic,
crosses placenta and the
blood-brain barrier.,
concentrates in CNS.
 Tightly bound to fish proteins.
 Enter human body thro’ fish
consumption.

24. Human  Breathing air containing
exposure to mercury vapors
mercury
 Drinking water
contaminated with mercury.
 Eating fish or shell fish
contaminated with mercury.
 Touching liquid mercury in
the event of a spill.

25. Health effects of mercury
 Disruption of the central nervous system
 Damage to brain, lungs and kidneys
 Damage to chromosomes and DNA.
 Allergic reactions, resulting in skin rashes,
tiredness headaches and vision problems.
 Negative reproductive effects, such as sperm
damage, birth defects and miscarriages

26. Cadmium contamination
Accumulates
in liver and
kidneys
Highly toxic Potent
Non- enzyme
essential inhibitor
Cadmium

27. Sources of cadmium contamination
 Mining and metallurgical operations
 Electroplating industry
 Manufacturing PVC plastics
 Ni-Cd batteries, paints , pigments and dyes
 Fertilizers and pesticides
 Anti-corrosive agent for steel, iron, copper,
brass and other alloys.
 Photo voltaic devices and TV screens.

28. Human health effects
 Cause diarrhoea, stomach pains and severe
vomiting
 Itai- itai disease-bone fracture
 Kidney dysfunction-chronic renal failure
 Reproductive failure and even infertility
 Damage to the central nervous system
 Damage to the immune system
 Psychological disorders
 DNA damage or cancer development

29. Environmental effects of cadmium
 Cadmium -rich sludge can pollute surface waters
as well as soils.
 Cadmium strongly adsorbs to organic matter in
soils.
 Soils that are acidified enhance the cadmium
uptake by plants.
 Cadmium can accumulate in the plant eating
animals , especially when they eat multiple
plants.
 In aquatic ecosystems, cadmium can
bioaccumulate in mussels, oysters, shrimps,
lobsters and fish.

30. Lead contamination
General
Metabolic
poison
Non-
Cumulative
essential
neurotoxin
element
Lead

31. Lead – Pb-contaminant
Atomic
Atomic weight
Number
207.19
82
Specific gravity Melting point
11.34 327.5 o C
Boiling point Bluish-grey
1740 0 C metal

32. Sources of lead contamination
 Industrial discharges from smelters and
battery manufacturing units
 Solders in electronics
 Sewage effluent
 Atmospheric fallouts from fossil fuel burning
 building industry for roofing and flashing and
for soundproofing
 Used in paints
 Used in pipes, ceramics and dishware
 Ammunition
 Lead is used in batteries and sinkers in fishing

33. Human health effects
 A general metabolic poison
 Acute exposure –kidney damage
 Chronic exposure – interstitial nephritis of kidney
 Inhibits haemoglobin synthesis and cause anemia
 Inhibits enzyme activity
 Neurological and reproductive dysfunctions
 Lead poisoning (also known as plumbism, colica
pictonium, saturnism, painter's colic) is a medical
condition.
 Lead breaks the blood-brain barrier and interferes
with the normal development of brain in infants

34. Environmental contamination of Lead
 Approx. 94% of the Pb in the atmosphere is derived
from heavy motor traffic in urban areas. The aerial
dispersion may lead to higher levels of Pb in rivers,
seas and soils.
 Lead gets into soil through paint, dry and wet
depositions from the atmosphere and industrial
effluents and solid discharges.
 Lead combine with colloidal particles found in
natural water.
 Urban run off cause pollution of surface and ground
water. Consumption of such untreated water may
lead to Pb poisoning.

35. Chromium - Cr
 Chromium is an abundant element of earth’s
crust.
 The trivalent (III) and hexavalent
(VI)compounds of chromium are great
industrial importance.
 Chromium(III) is an essential nutrient.

36. Human health effects of chromium
 Acute chromium toxicity cause renal
tubular necrosis.
 Chronic chromium toxicity cause cancers
of respiratory tract.
 Upset stomachs and ulcers
 Respiratory problems-lung cancer
 Weakened immune system
 Kidney and liver damage
 Teratogenic and carcinogenic action
 Death

37.  Chromium in air will eventually
settle and end up in waters or
Environmental soils
effects of
chromium
 Chromium in soils adsorbs to
soil particles and percolates to
ground water
 Chromium may adsorb on
sediments and become immobile
in water .

38. Arsenic contamination
Cumulative
poison
carcinogen
Trivalent
A toxic, non-
arsenites are
essential, semi-
more toxic than
metallic
pentavalent
element
arsenates
Arsenic

39.  Pesticides, herbicides
 Combustion of coal
 Mining, smelting of gold,
Sources of lead, copper and nickel
Arsenic
contamination  Production of iron and steel
 Leachate from abandoned
gold mines
 A wood preservative
 Tobacco smoke

40.  Birth defects
 Carcinogen: Lung cancer,
Skin and liver cancer,
Human health
cancers of the bladder and
effects kidneys
 Gastrointestinal damage
 Severe vomiting
 Diarrhea
 Death

41.  Cobalt has a melting point of
Cobalt 1495oC, boiling point of 2870oC,
contamination
specific gravity of 8.2 g/cm3 at
20oC, atomic number of 27,
atomic weight of 58.933 g/mol.
 Cobalt is hard, ductile and
lustrous bluish-grey in color.
 Cobalt is an essential element. It
is an integral component of
vitamin B12. It is therefore
required for good health.

42.  Manufacture of many alloys used in
gas turbine, aircraft engines,
corrosion resistant alloys, high speed
steels and cemented carbides.
 As catalysts for the petroleum and
Uses of cobalt chemical industries
 As drying agents for paints and inks
 Used as pigment in porcelain,
pottery, glass, tiles, and enamel
jewellery.
 Radioactive isotopes, cobalt-60, is
used in medical treatment and for
food preservation
 Treatment of anemia

43.  Mining and refining of cobalt
 Production of alloys
 Production of tungsten carbide
Sources of  Jewellery producers
cobalt
 Ceramics, porcelain producers
 Metallurgical industries

44.  Cobalt stimulates the production of
red blood cells, thus, used to treat
anemia. At high concentration may
Human
damage human health.
health effects
 In soil, it may adsorb on soil
of cobalt
particles and is only mobilized
under acidic condition. Cobalt is
also adsorbed on sediments.
 Cobalt may accumulate in plants
and in the bodies of animals that
eats these plants. Cobalt is not
known to bio-magnify up to the food
chain.

45.  Zinc is a lustrous bluish-white metal
whose atomic number and atomic mass
are 30 and 65.37 g/mol respectively.
Zinc  The density is 7-11 g/cm3 at 20oC with
contamination melting and boiling points at 420oC and
907oC respectively.
 zinc is brittle and crystalline at room
temperature but becomes ductile and
malleable between 110oC and 150oC.
 It is used for galvanizing steel and in
the preparation of alloys.

46. Uses of zinc
Zinc is used as the negative plates in batteries.
Zinc is utilized for roofing in building construction.
Zinc oxides is used as a white pigment in paints.
Zinc is used as pigment in plastic ,cosmetics,
photocopier paper, wallpaper, printing inks.
Zinc is utilized as a catalyst during rubber
production.
Zinc is used as drugs, as anti-oxidants and protect
against premature aging of the skin and muscle of
the body.

47. Occurrence of zinc
 Zinc is the most abundant element in the earth crust.
 It occurs naturally in air, water and soil.
 Zinc is an essential trace element required for the
function of over 200 metallo-enzymes.
 Zinc is also important in the regulation of DNA and
RNA synthesis via interaction with DNA binding
protein.
 It also plays a critical role in hormone-receptor
interaction

48.  Loss of appetite and fatigue
Human health  Decreased sense of taste and smell
effects of zinc
 Slow wound healing
 Skin sores
 Stomach cramps
 Nausea and vomiting
 Anemia
 Respiratory disease
 Eye irritation
 High exposure damage the pancreas
 Birth defect

49. Environmental effect of zinc
 Zinc in water (from wastewater of industrial plants)
increases the acidity of waters.
 Some fish can bio-accumulate Zn in their bodies.
 Zinc in fish can bio-magnify and enter human food
chain.
 Insoluble zinc in soils can contaminate groundwater.

50.  Dr.B.Victor is a highly experienced
professor, recently retired from the reputed
educational institution- St. Xavier’ s College,
Palayamkottai, India-627001.
 He was the dean of sciences, IQAC
coordinator and assistant controller of
examinations.
 He has more than 32 years of teaching and
research experience
 He has taught a diversity of college courses
and guided 12 Ph.D scholars.
 Send your comments to :
bonfiliusvictor@gmail.com