Transcript POLYCYCLIC AROMATIC HYDROCARBONS

POLYCYCLIC AROMATIC
HYDROCARBONS
PAHs
What are PAHs?
group of organic compounds
two 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
US EPA and in the European Union
priority lists of pollutants
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
PAHs are
introduced into the
environment
mainly via natural
and anthropogenic
burning processes.
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
They can also
enter surface water
through discharges
from industrial
plants and
wastewater
treatment plants.
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?
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?
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
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
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
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/ehc2
02.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
THANKS FOR YOUR ATTENTION