2. Prepared by-
Khandaker Abir Hasan
Department of Pharmacy
Noakhali Science and Technology University
Noakhali, Bangladesh
3. Introduction
What are heavy metals?
Heavy metals are naturally occurring elements that have a high atomic weight
or density and are toxic or poisonous at low concentrations.
Example: Mercury, Lead, Arsenic, Cadmium etc.
Mercury Lead CadmiumArsenic
4. Properties of heavy metals
Can be metal or metalloid (eg. Arsenic)
They occur near the bottom of the
periodic table
Their standard state have density of
more than 5 g/cm3
Toxic in nature
Non biodegradable
6. Introduction
Atomic number 80
Liquid at room temperature (20-25˚ C)
Most volatile of all metals
Highly toxic in vapor form
Liquid mercury is not highly toxic and most
of that ingested is excreted
7. Source
Source of MercuryNatural
Volcanoes
Forest fires
Fossil fuels
Man made
Power plant
Pulp and paper
industries
Combustion of coal
and medicinal
waste
Manufacture of
metal, alkali and
cement
9. Risk factors
Elemental Mercury:
Most common form
It is metallic, silvery liquid
Easily vaporize in room temperature into an
odorless, colorless vapour that can easily inhaled
Risks:
Easily crosses blood/brain and placental barriers and can enter breast milk
Potent neurotoxin
Neurological effects- tremors, mood swings, irritability
Very high exposure can cause kidney effects, respiratory failure and death
10. Risk factors
Inorganic Mercury:
White in color except cinnabar (red)
Least toxic of three forms
Enters body through mouth and skin
from disinfectant and fungicide
Usually used in science lab
Risks:
It can damage the GI tract, as well as the kidneys and nervous system
High exposures can lead to skin rashes, dermatitis, memory loss, mental
disturbance, and muscle weakness.
11. Risk factors
Organic Mercury:
Most commonly found organic mercury is methyl mercury and it
is the most toxic form of mercury
Converted from its inorganic form by biological bacterial process
Bio accumulates in environment most commonly found in fish
Ingestion of fish is most common route of human mercury
exposure
Risks:
Birth defects
Neurological problems
Impairment of vision, speech, walking
Extreme exposure leads to death
12. Effects of Mercury
Health effects:
Mercury exposure at high levels can harm the –
Brain, heart
Kidneys, lungs
Immune system of people of all ages
High levels of methyl mercury in the bloodstream of unborn babies and young
children may harm the developing nervous system.
Make the child less able to think and learn.
13. Effects of Mercury
Ecological effects:
Birds and mammals that eat fish are more exposed to mercury than other animals
in ecosystems.
Similarly, predators that eat fish-eating animals may be highly exposed.
At high levels of exposure, methylmercury’s harmful effects on these animals
include:
Death, reduced reproduction
Slower growth and development, abnormal behaviour
14. Exposure of Mercury
Mercury in the air eventually settles
into water or onto land where it can be
washed into water.
Once deposited, certain micro-
organisms can change it into
methylmercury.
This highly toxic form of mercury
builds up in fish, shellfish and animals
that eat fish.
Methyl mercury builds up more in
some types of fish and shellfish than
others.
Fish and shellfish are the main sources
15. Exposure of Mercury
Another common exposure to mercury that can be a concern is breathing
mercury vapour.
These exposures can occur when elemental mercury or products that contain
elemental mercury break and release mercury to the air.
Particularly in warm or poorly ventilated indoor spaces.
16. Diseases
Minamata disease:
Minamata disease, sometimes referred to as
Chisso-Minamata disease, is a neurological
syndrome caused by severe mercury
poisoning.
Symptoms:
General cases
Muscle weakness
Damage to hearing, vision and speech
Crippling hands and feet
Extreme cases
Paralysis
Coma
Death
17. Diseases
Pink disease:
Methylmercury exposure in children may result in acrodynia in
which the skin becomes pink and peels and that is called pink
disease.
Symptoms:
Irritability
Neurosis
Photophobia (light sensitivity)
Hyperhidrosis (excessive sweating)
Hypotonia (low muscle tone)
Ataxia (lack of co-ordination)
19. Treatment for Mercury poisoning
Chelation therapy:
Chelation therapy is the administration of chealating agents which bind mercury
ions and facilitate their excretion through urine and feces.
Approved chelating drugs for mercury poisoning include-
Succimer (DMSA, 2,3-dimercaptosuccinic acid) is taken by mouth
Dimercaprol (British Anti-Lewisite, BAL) is given by injection
DMSA BAL
20. Treatment for mercury poisoning
Medicinal
charcoal:
Mercury absorbs with charcoal’s surface and hence gets
removed without being absorbed by enterocytes.
Dialysis
:
If kidneys show signs of damage, alkaline fluids;
peritoneal dialysis or hemodialysis may be necessary.
21. Prevention for Mercury poisoning
Mercury poisoning prevention at home
People of all over use some products as their daily driver. They are advised to read
the labels on products to see if they contain mercury, have warning labels about
potential threat.
Mercury Poisoning Prevention - Amalgam Fillings
Mercury can be found in dental amalgam fillings.
There are several types of dental filling material that
can be used so individuals are urged to discuss choices
for dental fillings with their dentist.
22. Prevention for Mercury poisoning
Mercury Poisoning Prevention - Fish and Shellfish
1. Abstain from consuming shark, swordfish, king mackerel, or tilefish because they
contain high levels of mercury
2. Eat up to 12 ounces a week of a variety of fish and shellfish that are lower in
mercury
3. Another commonly eaten fish, albacore ("white") tuna has more mercury than
canned light tuna and we have to cast aside this one while taking food
Mercury Poisoning Prevention - Vaccines
People are now concerned at the use of thimerosal, a mercury-containing preservative
used in vaccine preparations. However, the amount of mercury in thimerosal is very
low. In 2008, the CDC recommended that current flu vaccines are safe to use in
pregnant women and children because they contain very little mercury traces.
24. Introduction
Arsenic is a chemical element with the symbol As
and atomic number 33
It is a metalloid
It has a specific gravity of 5.7 g/cm3
It has various allotropes existing in both gray and
yellow crystalline forms.
Atomic Number : 33
Atomic Weight : 74.9
Oxidation States : -3,+3,+5
25. Source
Sources of arsenic are classified into 2 types. They are-
1. Natural Sources
Rocks And Soil
Water
Forest Fire
Air
Fish ,Vegetables, Fruits
Earth’s Crust
2. Industrial Process
Glass Manufacturing
Semi-Conductor (Gallium Arsenide)
Fossil Fuel
Smelting and Coal fine power plants
26. Types
Arsenic is classified into 2 types. They are -
Arsenic
Inorganic
Arsenic
Organic Arsenic
Example-
Arsenic Trioxide
Sodium Arsenic
Toxic
Non-Toxic
Example-
Arsenobetine
(Seafood)
28. Mode of action
Arsenic interferes with cellular respiration by combining with the sulfhydryl
groups (-SH) of mitochondrial enzymes.
It particularly targets vascular endothelium leading
to increased permeability, tissue edema and
hemorrhage, especially in the intestinal canal.
29. Mode of action
It replaces phosphorus in bones where it may remain for years.
Locally it causes irritation of the mucous membranes and remotely depression of
the nervous system.
Arsenic also interferes with glycolysis.
30. Absorption and excretion
It can be inhaled and absorbed through the skin or through GIT after ingestion.
Once absorbed, arsenic rapidly combines with the globin's portion of
hemoglobin and therefore localize in the blood. Within 24 hours it distribute to
liver, kidney, spleen, lung and GI tract with lesser accumulation in the muscle and
nervous tissue.
Absorption:
Excretion:
Excreted mainly through kidneys as methylated arsenic and some part by faeces,
sweat, bile.
It becomes fixed in cancellous tissue or bones. Replaces phosphorus.
32. Symptoms
Acute as poisoning-
o Nausea
o Vomiting
o Blood in the urine
o Cramping muscle
o Hair loss
o Stomach pain
o Loss of appetite
Chronic as poisoning-
o Vitamin A deficiency
o Skin color change
o Eye inflammation
o Cardiovascular disease
o Diabetes
33. Black foot disease and symptoms
Symptoms:
Formation of black pustules on the feet
The pustules can be very painful
A foul odor
34. Treatment
Consumption of only arsenic free water.
Zinc, Selenium and Vitamin A for repair of the damaged skin.
For Gastric Lavage, 1% Sodium Thiosulphate in water is helpful.
Hemodialysis is the line of choice in massive arsenic poisoning.
Purgatives like castor oil and magnesium sulphate is administered to diminish
intestinal absorption of arsenic poisoning.
Blood transfusions and exchange transfusions may help the patient.
35. Medication
Medicines used to treat arsenic poisoning :
1. Dimercaprol ( BAL)
Intravenous Injection
Drug Class : Antidote, Chelating agent
Side Effects: Rise in BP, Tingling, Headache and
Anxiety
Dose : 3-4 mg/kg; 4 hourly for 2 days, 6 hourly for 1
day.
36. Medication
2. Succimer
Orally effective tablets / capsules
Drug class : Antidote, Chelating agent
Side effects : Nausea, Anorexia and loose motion
Dose : 10mg/kg : Every 8 hourly for 10 days
37. Prevention
Arsenicosis, as a public health problem, is a comparatively recent concept, for
which effective treatment measures are still not known. So it is a good decision to
prevent arsenic instead of medication after disease.
1. Identification of unsafe water sources:
Identifying the existing water sources having
arsenic concentration above the maximum
contaminant level (0.010 ppm or 0.010 mg/L)
Paint tube wells or hand pumps with different
colors.
38. Prevention
2. Methods of removal of arsenic from the arsenic
contaminated water:
Install arsenic removal
systems– either centralized
or domestic. Technologies
for arsenic removal include
oxidation, coagulation-
flocculation, absorption, ion
exchange, and membrane
technologies.
39. Prevention
3. Development of alternative sources of arsenic-free water:
Since arsenic removal technologies are all in their development phase and yet to become
fully reliable, it becomes imperative to search for alternate safe sources.
Surface water-based alternate sources can be pond, sand filters, rainwater
harvesting, or piped water supply
Ground water-based techniques can be either dug wells or deep tube wells from safe
aquifers.
Well Sand filter Rainfall water collection
40. Social awareness on Arsenic poisoning
Increasing awareness of the community regarding this deadly disease arsenicosis by
following way-
Drinking water should be clean
Make sure that all foods are prepared with clean water
Safe water supply for irrigation of food crops
Smoking should be prohibited.
41. Social awareness on Mercury poisoning
Should avoid certain fish & seafood which have high level of mercury such as
shark, swordfish.
Consumption food should be mercury free.
Drinking water should be mercury free.
Have to take medicine sufficient which contain mercury.
Have to telecast the bad effect & safety side on mercury toxicity.
42. Conclusion
Both of the Hg & As have some bad effect on environment & human life. To
get a beautiful life man should rise social awareness on Hg & As toxicity. This
process may be avoided smoking & heavy metal containing food & may be
taken pure water which has no Hg & As. Finally, we can say that As & Hg are
not main matter, the matter is to change our mentality. By changing our
mentality we can ensure safety in our life on heavy metal toxicity.