Heavy metal toxicity in enviroment

1. BY-
AMAN SINGH,
M.SC Student
Supervised by-
Dr.vinita khatri

2.  Those metals with a specific gravity of greater than
4.0.
 Mainly produced from industrial activities
 most hazardous heavy metals are-
1. arsenic (As)
2. lead (Pb)
3. mercury (Hg)
4. cadmium (Cd)
 Toxic metals are metals that form poisonous soluble
compounds and have no biological role, or are in the
wrong form.

3.  Toxicity is a function of solubility. Insoluble
compounds as well as the metallic forms
often exhibit negligible toxicity. In some
cases, organometallic forms, such as
dimethyl mercury and tetraethyl lead, can be
extremely toxic.

4. 1. The total dose absorbed
2. The exposure either acute or chronic.
3. Age of the person
E.G.-Young children are more
susceptible to lead

5. 4- The route of exposure
 E.g.- Elemental mercury is inert in the
gastrointestinal tract and through
intact skin, but inhaled or injected
elemental mercury have disastrous
effects.

8.  Arsenic is the most common cause of acute
heavy metal poisoning in adults and is
number 1 on the Top Hazardous
Substances.
 Used as weed killers, wood preservatives,
pesticides, rodenticides and hardening
agents

9.  Arsine gas is a common byproduct produced
by the manufacturing of pesticides that
contain arsenic.
 Arsenic may be also be found in water
supplies worldwide, leading to exposure of
fishes
 Target organs are the blood, kidneys, and
central nervous, digestive, and keratinized
tissues (skin, hair and nails)

10. • Arsenic exists in the environment in major three forms,
organic and inorganic arsenic compounds in addition to
Arsine gas.
• Organic arsenic is 500 times less
harmful than inorganic arsenic.
• Organic arsenic exposure can occur by eating food especially
seafood.
• Two forms of inorganic arsenic, reduced (trivalent As (III)) and
oxidized (pentavalent As(V)) are existed. Unlike the organic
form, inorganic arsenic is quite harmful even in minute
quantities.
• Inorganic arsenic poisoning can be related to human activities
such as mining and smelting but is more often associated with
dissolved solids naturally in ground water and soil.
Mood of Exposure

11. Acute toxicity:
 Acute exposure to arsenic compounds can
cause nausea, anorexia, vomiting
(hematemesis), abdominal pain, muscle
cramps.
 Carcinogenic: cancers of the skin, liver,
respiratory tract, kidney, bladder and
gastrointestinal tract are well documented in
regards to arsenic exposure.

13.  Lead is ranked 2nd on“the Top
Hazardous Substances”
 Lead is a ubiquitous toxicant in the
environment. It is one of the oldest chemical
toxins and lead poisoning is probably the
most important chronic environmental illness
affecting modern children.

14.  In the environment lead is in organic
and inorganic compounds.
 Inorganic lead compounds are less
toxic

15. Occupational
exposure
 Battery makers
 Cable makers
 Glass makers/polishers
 Gunshot/gun barrel makers
 Jewelers
 Lead burners
 Painters
 Pigment makers
 Pipe cutters
 Printers
Non-occupational
exposure
 Battery burning
 Bullet retention
 Cooking in leaden pots
 Ingestion of paints
 gasoline
 cigarette smoke.
 surface paints on the toys.
 stagnant water in pipes.

16. 1. GI tract
 Children are at greater risk for lead
absorption(adults:11%-16%,children : 40% -
50%)
 Absorption increased with fe, ca, zn
deficiency
2. Lungs
 50% - 70% if < 1 μm
3. Skin
 Inorganic lead is non-absorbable
 Organic lead is readily absorbed

17. 1. Kidney is responsible for 65% of lead’s
elimination
 Process is dependent on glomerular
filtration rate and renal plasma flow
2. Biliary excretion is responsible for 35% of
lead’s elimination

18. • Early symptoms-
- Muscle weakness, and paresthesias
- Confusion/ irritability
- Metallic taste in mouth.
 Late complication-
Diminished libido
Anemia

20.  3rd on the top hazardous substances.
 Naturally-degassing of the earth's crust and
volcanic eruption.
 Mining, smelting, and industrial discharges
 Atmospheric mercury comes to the earth in
rain
 Paint, fungicide .
 Thermometers, thermostats, fluorescent light
bulbs, amalgams

21.  Acute toxicity-
 vomiting, constipation, ataxia,
somnolence
 Chronic toxicity (plumbism)
 Low-level exposure over a long time

22.  Three forms
 Elemental
› Inhalation(main source)
› Poorly through GI tract, Skin contact
 Inorganic
› Poorly through GI tract(7-15%).
› Dermal exposure causes toxicity
 Organic
› Lipid soluble
› well absorbed via GI (90-100%); lungs and skin
› Cross BBB and affects CNS
› Can cross placenta and into breast milk

23. Hg cycle

24.  After eating methyl mercury containing
fish neurologic damage such as visual
loss, extremity numbness, hearing loss.

25.  2 ppb in drinking water
 1 part of methylmercury in a million parts
of seafood.
 0.1 mg of organic mercury per cubic
meter of workplace air for 8 hrs

27.  Soils and rocks
 Coal and mineral fertilizers
 Batteries,
 Pigments
 Metal coatings
 Plastics
 Electroplating.
 Tobacco smoking largest source

28.  Acute-
 Vomiting and diarrhoea.
 Severe respiratory irritation
 Chronic-
 Kidneys damage mostly PCT(increased
excretion of α 2, β 2, gamma globulins)
 Lung damage(occupational exposure)
 Fragile bones(loss of ca in urine)
 Testicular degeneration
 prostate cancer.

29. 1. severe renal dysfunction
2. damage to bone structure.
3. elderly multiparous women mostly affected

30.  EPA – 5 ppb cadmium in drinking water
 FDA – concentration in bottled drinking
water should not exceed 0.005 ppm
 OSHA – an average of 5 µg/cu.m. of
workplace air for an 8-hour workday