polycyclic aromatic hydrocarbons n.
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POLYCYCLIC AROMATIC HYDROCARBONS. PAHs. What are PAHs?. group of organic compounds t wo or more aromatic (benzene) rings are fused together. potential health risk due to their inner chemical stability, high reactivity to different types of degradation and high toxicity to living organisms

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Presentation Transcript
what are pahs
What are PAHs?
  • group of organic compounds
  • two or more aromatic (benzene) rings are fused together
slide3
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
physical chemical properties
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.
enter the enviroment
Enter the enviroment
  • PAHs are introduced into the environment mainly via natural and anthropogenic burning processes.
enter the enviroment air
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.

enter the enviroment water
Enter the enviroment - Water
  • They can also enter surface water through discharges from industrial plants and wastewater treatment plants.
enter the enviroment soil
Enter the enviroment - Soil
  • Most PAHs don‘t 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.
how might i be exposed to pahs
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.
how likely are pahs to cause cancer
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).
medical tests show pahs in the body
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.
analytical determination of pahs
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.

more information
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
vocabulary
fuse - splynout

lists of pollutants – seznam

škodlivin

pale - bledý

to vary - lišit se

faint - mdlý

to release - uvolňovat

exhaust - výfukový plyn

evaporate-vypařovat se

discharge - vylučování

wastewater treatment plant -

čistička odp. vod

wastewater treatment plant - čistička odp. vod

to stick - přilnout

to settle - usadit se

vapor - pára

to develope - rozvinout se

ingested - přijímat potravou

to be available - být k dispozici

to attach - připojit

within - uvnitř

body tissues - tělní tkáně

Vocabulary