POLYCYCLIC AROMATIC HYDROCARBONS

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POLYCYCLIC AROMATIC HYDROCARBONS

• PAHs

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What are PAHs?

• group of organic compounds
• two or more aromatic (benzene) rings are fused
  together

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• potential health risk due to their inner chemical
  stability, high reactivity to different types of
  degradation and high toxicity to living organisms
• US EPA and in the European Union priority lists
  of pollutants

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Physical chemical properties

• Physical and chemical properties of PAHs vary
  with Mr.
• PAHs as pure chemicals exist as colorless, white,
  or pale yellow-green solids.
• They are non-polar, hydrophobic compounds, which
  do not ionize.
• They have a faint odor.

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Enter the enviroment

• PAHs are introduced into the environment mainly
  via natural and anthropogenic burning processes.

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Enter the enviroment - Air

• PAHs enter air as releases from volcanoes,
  forest fires, residental wood burning and
  exhausts from cars.
• Some PAH particles can readily evaporate into
  the air from soil or surface waters.

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Enter the enviroment - Water

• They can also enter surface water through
  discharges from industrial plants and wastewater
  treatment plants.

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Enter the enviroment - Soil

• Most PAHs dont dissolve easily in water.
• They stick to solid particles and settle to the
  bottoms of lakes or rivers.
• PAHs in soils also contaminate underground water.

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How might I be exposed to PAHs?

• We are most likely to be exposed to PAH vapors
  or PAHs that are attached to dust and other
  particles in the air.
• Sources include cigarette smoke, vehicle,
  exhausts, asphalt roads, coal, etc.

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How likely are (PAHs) to cause cancer?

• Breathing or touching mixtures of PAHs and other
  chemicals for long periods of time have developed
  cancer.
• Some PAHs have caused cancer in laboratory
  animals when they breathed air containing them
  (lung cancer), ingested them in food (stomach
  cancer), or had them applied to their skin (skin
  cancer).

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Medical tests show PAHs in the body

• In the body, PAHs are changed into chemicals that
  can attach to substances within the body.
• Special tests that can detect PAHs in body
  tissues or blood.
• The tests aren't usually available in your
  doctor's office.

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Analytical determination of PAHs

• Samples of PAHs are mostly analysed by HPLC
  using fluorence detection, or by gas
  chromatography method with flame ionizazion
  detection, or mass spectrometry.

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More information

• For more information you can visit this pages
• http//www.atsdr.cdc.gov/toxprofiles/tp69.pdf
• http//wlapwww.gov.bc.ca/wat/wq/BCguidelines/pahs/
  
• http//www.inchem.org/documents/ehc/ehc/ehc202.htm

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Vocabulary

• fuse - splynout
• lists of pollutants seznam
• škodlivin
• pale - bledý
• to vary - lišit se
• faint - mdlý
• to release - uvolnovat
• exhaust - výfukový plyn
• evaporate - vyparovat se
• discharge - vylucování
• wastewater treatment plant -
• cisticka odp. vod

• wastewater treatment plant - cisticka odp. vod
• to stick - prilnout
• to settle - usadit se
• vapor - pára
• to develope - rozvinout se
• ingested - prijímat potravou
• to be available - být k dispozici
• to attach - pripojit
• within - uvnitr
• body tissues - telní tkáne

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• THANKS FOR YOUR ATTENTION