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Polycyclic Aromatic Hydrocarbons (Part1)

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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

    http://en.wikipedia.org/wiki/Pyrenehttp://en.wikipedia.org/wiki/Pyrene
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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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