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large grp. of hydrocarbons containing
two or more benzene ring fused
together or to other hydrocarbon rings
mainly formed as pyrolysis by-
products
usually exist a mixtures
lipophilic, less volatile
PAHs can either be synthetic or non-
synthetic
possess many absorbance bands
fluorescent
An illustration of
typical polycyclic
aromatic
hydrocarbons.Clockwise from top
left:
benz[e]acephenanthryl
ene, pyrene and
dibenz[a,h]anthracene
Definition
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Research purposes
Medicines
Used to make dyes, plastic, and
pesticides
Road construction
Uses
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Alternant
Non- alternant
-equal distribution of e density
-benzenoid PAHs
-uneven distribution of e density
Benzo[a]pyreneBenz[a]anthraceneChryseneDibenz[a,h]anthracene
FluorantheneBenzo[k]fluorantheneBenzo[i]fluoranthene
Indeno[1,2,3-c,d]pyrene
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Chemical compound Chemical compound
Anthracene Benzo[a]pyrene
Chrysene Coronene
Corannulene Naphthacene
Naphthalene Pentacene
Phenanthrene Pyrene
Triphenylene Ovalene
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Forest fires
Comets
And Volcanic activities
Meteorites
Bacterial decay of organic materials
Sources
Natural/
non-synthetic
Synthetic
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Aluminum production
Coke production
Iron & steel
Refinery & oil storage
wastes
Thermal power plant
occupational exposure
Sources
Natural/
non-synthetic
Synthetic
Automobile
Domestic
Human habitats
Others
Industrial
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motor vehicle emissions
burning & incomplete
combustion of diesel and
gasoline
air craft engine
Natural/
non-synthetic
Synthetic
Automobile
Domestic
Human habitats
Others
Industrial
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Domestic
-cooking (fuel burning)
-waste refuse incineration
Human habitats
-tobacco & cigarette smoke
-smoke, charcoal broiled, orpan fried foods
Natural/
non-synthetic
Synthetic
Automobile
Domestic
Human habitats
Others
Industrial
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rural and urban sewage sludge municipal wastewater discharges run off
surface soils
surface waters
river borne pollution
commercial and pleasure boating
activities
special purpose skin creams
Natural/
non-synthetic
Synthetic
Automobile
Domestic
Human habitats
Others
Industrial
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Coal combustion :phenenthrene, fluoranthene, pyrene
Coke production :anthracene,phenenthrene,benzo(a)pyrene
Incineration :pyrene, phenenthrene, fluorantheneWood combustion :benzo(a)pyrene, fluoranthene
Industrial oil burning :fluoranthene, pyrene, chrysene
Petrol powered vehicles :fluoranthene, pyrene w/higher ratios ofbenzo(b)fluoranthene &
benzo(k)fluoranthene, thiophene cmpds.
Diesel powered vehicles :fluoranthene, pyrene w/higher ratios ofbenzo(b)fluoranthene &
benzo(k)fluoranthene, thiophene cmpds.
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PAHs enter the air mostly as releases from burning coal, cokeoven plant, automobile exhaust and wood fire.
PAHs remains in air attached to dust particles.
Most PAHs do not dissolve easily in water. They stick to solid
particles and settle to the bottom of lakes or rivers.
Microorganisms break down PAHs in soil or water after a periodof weeks to months.
In soil, PAHs are most likely to stick tightly to particles. CertainPAHs move through soil to contaminate ground water.
PAHs in remote areas such as arctic & marine atmosphere areresult of long range transport.
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Cancer (lung, skin)
Reproductive effects
Organ-system damage
Capable of depositing in the airways
and alveoli
Effects
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Breathing air containing PAHs in theworkplace of coal, tar and asphalt production
plants, smoke houses and municipal incinerators
Breathing air containing PAHs from cigarettesmoke, wood smoke, vehicle exhaust andasphalt
Coming in contact with air, water or soil ,near hazardous waste site
Eating contaminated cereals, flour,. Bread,vegetables, fruits, meats
Drinking contaminated water or milk
Nursing infants of mothers living nearhazardous waste sites may be exposed to PAHsthrough their mother's milk
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Yes, you can get sick from PAHs. But gettingsick will depend on:
How much you were exposed to (dose)
How long you were exposed (duration)
How often you were exposed (frequency)
Route of exposure: Ingesting (eating) andinhaling (breathing) is more of a risk thandermal (skin) exposure
General Health, age, lifestyle: Youngchildren, the elderly and people withchronic (on going) health problems are moreat risk to chemical exposures
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PAHs are absorbedthrough:
Inhalation
Ingestion Dermal contact
PAHs can enter your body through your lungs
when you breathe air
Occupational studies provide evidence that
inhaled PAHs are absorbed by humans
inhaled PAHs are predominantly adsorbed on
soot particles
After deposition in the airways, the particles
can be eliminated by bronchial clearance
PAHs might be partly removed from the
particles during transport on the ciliated mucosa
and may penetrate into the bronchial epithelium
cells where metabolism takes place
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PAHs are absorbedthrough:
Inhalation
Ingestion Dermal contact
PAHs can enter your body through drinking
water and swallowing food, soil or dust particlesthat contain PAHs
But absorption is generally slow when PAHs
are swallowed because generally you will not be
ingesting large amounts of PAHs
BaP and other PAHs are readily absorbed from
the gastrointestinal tract when present as
solutes in various dietary lipids.
Oral absorption increases with more lipophilic
compounds
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PAHs are absorbedthrough:
Inhalation
Ingestion Dermal contact
PAHs could enter your body if your skin comes
into contact with soil that contains high levelsof PAHs
Studies have shown that low molecular
weight (lighter) PAHs can be absorbed through
the skin but the absorption of high molecularweight (heavy) PAHs is quite limited
Dermal absorption depends on:
Molecular weight
Rapid tissue deposition after absorption
Metabolic conjugation with rapid urine
Excretion
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Once absorbed, PAHs:
enter the body
circulate in the blood
metabolized primarily in the liver and kidney
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The pattern of distribution of PAHs was
found to be similar after oral, dermal and
respiratory administration.
Detectable levels of PAHs can be observed
in most internal organs from minutes to hours
after administration.
Highest levels are obtained in the liver.
Mammary and other fatty tissues are
significant storage depots for PAHs, but owing
to the rapid metabolism no significant
accumulation seems to take place.
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For pyrene, the distribution to the tissues
was highest in the liver, kidneys and lungs,
and lowest in the heart, testes, spleen and
brain
PAHs differ with respect to distribution
patterns and lipophilic properties [Busbee et
al. 1990].
Because of their lipophilic nature, PAHs
can accumulate in breast milk and adipose
tissue.
However, biliary and urinary excretion of
PAHs is relatively efficient because of the
wide distribution of enzymes that transform
PAHs into polar metabolites.
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The lipophilicity of PAHs enables them toreadily penetrate to the human body and
remain there indefinitely.
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The enzyme primarily responsible for PAH
metabolism is the microsomal mixed function
oxidase system.
Epoxides are the major intermediates in
oxidative metabolism of aromatic double
bonds.
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S O
NH
CH
2
C
O
O
NH
O
NH2
C O
O
OH
OH
OH
Glutathione-S-Transferase
Glutathione-S-
Urine
O
OH
OH
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Diol epoxides are highly reactive and
mutagenic.
Potent carcinogen bay region benzopyrene bay region is the space between the aromatic
rings of PAH molecules
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Metabolizing Capacity
Liver>lung>intestinal mucosa> skin> kidneys.
Metabolism may also take place in nasal
tissues, mammary glands, spleen, brain, hair
follicles, erythrocytes, platelets, leukocytes,
placenta and uterus.
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Animal and Human fetal tissues are able to
metabolize PAH but in a low rate compared
to adult tissues.
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Glucuronide and Glutathione sulfate
conjugates are excreted in the bile and in
urine.
Glutathione conjugates are further
metabolized in the kidneys to form
mercaptouric acids and excreted as urine
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The hydroxylated metabolites of PAHs are
excreted in the urine both as free
hydroxylated metabolite or hydroxylated
metabolite conjugated with glucuronic acids
or sulfate.
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The most common measured metabolite is 1-
hydroxypyrene.
Metabolism is a prerequisite for hepatobiliaryexcretion and elimination through the feces
regardless of the route of entry.
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Very structurally dependent, withisomers (PAHs with the same formula
and number of rings) varying from
being nontoxic to being extremely toxic
benzo[a]pyrene- first chemicalcarcinogen to be discovered
High prenatal exposure to PAH is
associated with lower IQ.
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PAHs can affect lungs (when swallowed and
which can lead to pneumonia), central nervous
system, the heart, bone marrow, and kidneys
Signs of hydrocarbon poisoning may include
severe coughing, stomach problems, nausea,
drowsiness and poor coordination. This may lead
to seizures.
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PAHs are changed into chemicals that can
attach to substances within the body.
The presence of PAHs attached to these
substances can then be measured in body tissues
or blood after exposure to PAHs.
PAHs or their metabolites can also bemeasured in urine, blood, or body tissues.
R ti t f
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Remove patient from exposure
The patient should remove all clothing and
personal effects
Double-bag soiled clothing and place in sealed
container clearly labeled biohazard
Brush away any adherent solid particles from
the patient
Wash hair and all contaminated skin with
copious amounts of water (preferably warm) and
soap for at least 10-15 minutes. Decontaminateopen wounds first and avoid contamination of
unexposed skin
Pay attention to skin folds, axillae, ears,
fingernails, genital areas and feet.
Decontaminationand First Aid
Dermal contact
Ocular exposure
Inhalation
Ingestion
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Remove patient from exposure
Remove contact lenses if necessary and
immediately irrigate the affected eye
thoroughly with water or 0.9% saline for at
least 10-15 minutes
Patients with corneal damage or those
whose symptoms do not resolve rapidly
should be referred for urgentophthalmological assessment
Decontaminationand First Aid
Dermal contact
Ocular exposure
Inhalation
Ingestion
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Remove patient from exposure
Ensure a clear airway and adequate
ventilation
Give oxygen to symptomatic patients
Apply other supportive measures as
indicated by the patients clinical
conditon
Decontaminationand First Aid
Dermal contact
Ocular exposure
Inhalation
Ingestion
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Give oxygen to symptomatic patients
Apply other supportive measures as
indicated by the patients clinical
conditon
Decontaminationand First Aid
Dermal contact
Ocular exposure
Inhalation
Ingestion
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Chimney sweeps
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Polynuclear aromatic hydrocarbons (PAH). In: Air
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oly uclea a o at c yd oca bo s ( ). :
quality guidelines for Europe.Copenhagen,World
Health Organization Regional Office for Europe,
1987, pp. 105117.
BAEK, S.O. ET AL. A review of atmospheric
polycyclic aromatic hydrocarbons: sources, fate and
behavior. Water, air, and soil pollution, 60: 279300
(1991).
Glenn Michael Roy (1995). Activated carbonapplications in the food and pharmaceutical
industries. CRC Press. p. 125. ISBN 1566761980.
http://books.google.com/books?
id=nmmpK0oDE20C&pg=PA125.
Agency for Toxic Substances and Disease Registry
(ATSDR). 1995. Toxicological profile for polycyclic
aromatic hydrocarbons (PAHs). Atlanta, GA: U.S.
Department of Health and Human Services, Public
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