Arsenic is a heavy metal occurring naturally in the environment. It's low concentration is important for various life processes on the Earth but the misuse and overexploitation of mineral resources caused the arsenic contamination to natural resources, which in turn get exposed to living beings causing various toxicity problems and severe health issues. Arsenic has not remained an important mineral for sustaining life but it becomes a category pollutant for which heavy precautions should be taken to avoid an exposure.

2. Arsenic
o Arsenic is an element and naturally
occurring mineral
o Ubiquitous in the environment
o A solid metalloid and has a low solubility

3. Arsenic
o Exists in four common valence states:
 As (0) (metalloid arsenic , 0 oxidation state)
 As (III) (trivalent, 3 oxidation state, such as
Arsenites )
 As (V) (pentavalent, 5 oxidation state, such as
Arsenates )
 Arsine gas

4. Sources of Arsenic
Volcanoes Smelting of metals
Rocks and mineral deposits Industrial processes
Forest fires Fossil fuel burning
Ground water Waste incineration
Mineral extraction
Sources
Natural Anthropogeni
c

5. Uses of Arsenic
Pesticides and insecticides
Arsenic trioxide may be found in pesticides
and defoliants.
Electronic industry
Gallium arsenide and arsine gas are used
in semiconductor devices.
Used in wood preservatives.

6. Uses of Arsenic
• Drugs and chemical treatments.
• Metal and other industrial processes.
• Found in foods, especially in sea foods.
• Colouring dyes and cosmetics.

7. o Inorganic arsenic is generally more toxic than
organic arsenic.
o Arsenite and Arsenate are the inorganic forms
such as Arsenic trioxide, Sodium arsenate,
Arsenic sulphide, Copper arsenate, etc.
o Arsenobetaine and Arsenocholine are the
organic forms known as “ Fish arsenic” found in
seafood.
o Arsine gas is the most toxic arsenical.
Poisonous compounds of Arsenic

8. Arsenic exposure
 Ingestion
 Arsenic containing foods – meat, fish, seafood
 Drinking well water
 Drugs
 Inhalation
 Burning of fossil fuel containing arsenic
 Cotton gins
 Emission from industrial operations
 Smelters
 Pesticides
 Tobacco smoke
 Dermal
 Preserved wood products
 Clothes using dyes

9. Toxicity by form
Arsenic is a known human carcinogen. It can cause cell injury and death by
multiple mechanisms. Toxicity may vary by the forms:
 metalloid arsenic is generally regarded as nonpoisonous due to its
insolubility in
water and body fluids.
 Trivalent, methylated, and relatively less ionizable arsenic metabolites
may be
capable of interacting with cellular targets such as proteins and even
DNA.
 The half life of inorganic arsenic in humans is about 10 hours.
 After inhalation, arsine gas rapidly binds to red blood cells, producing
irreversible
cell membrane damage.

10. Effects of arsenic exposure
Because it targets widely dispersed enzyme reactions, arsenic
affects
nearly all organ systems :
1. Gastrointestinal and Hepatic effects
 GI effects are generally the result of ingestion.
 GI lesion appears to be increased permeability of the small blood
vessels, leading to fluid loss and hypotension.
 Extensive inflammation and necrosis in stomach and intestine.
 Hemorrhagic gastroenteritis may develop, with bloody diarrhea.
 Toxic hepatitis with elevated liver enzyme levels.
 Chronic arsenic ingestion may lead to cirrhotic portal
hypertension.

11. 2. Cardiovascular effects
 Acute arsenic toxicity may cause diffuse capillary leakage and
cardiomyopathy, resulting in shock.
 Hypertension with long-term exposure to arsenic.
 Increased cardiovascular mortality in occupationally exposed
groups.
3. Neurologic effects
 Arsenic poisoning can cause peripheral neuropathy
which leads to increased sweating, muscle cramps,
numbness and spontaneous pain.
 Sensory effects, particularly painful dysesthesia
occur in moderate poisoning.
 Weakness and paralysis may occur in more severe
poisoning.
 Cranial nerves are rarely affected.
 Encephalopathy has been reported after both acute
chronic exposure.

12. 4. Dermal effects
 Skin lesions occurring most frequently in
arsenic exposed humans are- hyperkeratosis,
hyperpigmentation and skin cancer.
 Patchy hyperpigmentation, a pathologic hallmark
of chronic exposure may be found anywhere on
the body.
 Arsenical hyperkeratosis occurs most frequently
on the palm and soles.
 Skin cancer over a long-term exposure.
5. Renal effects
 Severe acute arsenic poisoning may cause acute
tubular necrosis with acute renal failure.
 Chronic renal insufficiency from cortical necrosis has been
reported.
 There is limited strength of association between chronic arsenic
exposure and renal cancer.
 Arsine gas is more nephrotoxic than arsenic. however, both can
cause acute tubular necrosis.

13. 6. Respiratory effects
 Irritation of the respiratory mucosa.
 Erosive lesions of mucosa including nasal septum perforation due
to prolonged exposure of airborne arsenic.
 Lung cancer has been associated with chronic arsenic exposure.
7. Carcinogenic effects
In humans, chronic arsenic ingestion may cause cancers of the
 Bladder
 Kidney
 Liver
 Lung
 Prostate, and
 Skin
Arsenic exposure also associated with tumors of the bladder, kidney,
liver,
lung, and prostate.

14. Arsenic in India and Bangladesh
Well water contaminated by
natural sources containing
arsenic has been reported to be
the cause of arsenic toxicity
throughout the world.
Arsenic in drinking water has
attracted much attention since
recognition in the 1990s of its
wide occurrence in well-water in
Bangladesh.
About 20% of wells in
Bangladesh are contaminated
and an estimated 80 million
people are dependent on those
wells for domestic purposes and
affected by arsenic poisoning.

16. Standards for arsenic exposure
The U.S Environment Protection Agency (EPA)
adopted
the standards for arsenic in workplace, food, and
drinking water.
the permissible limit for arsenic:
• Workplace - 10µg of inorganic arsenic /m³ of air
• Drinking water - 10 ppb
• Food - 0.5 ppm to 2 ppm in seafood and other
animal foods.