PCBs and PAHs


Published on

  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

PCBs and PAHs

  1. 1. PCBs and PAHs: Measurement and Effects Presented by: SURAYYA MUHD LAMIDO 20122555 ENVS 509 ADVANCED AIR POLLUTION
  2. 2. THE DOSE MAKES THE POISON All Substances are poisonous There is none which is Not a poison The Right dose differentiate a poison and a Remedy. Paracelsus (1493-1541)
  3. 3. POLYCHLORINATED BIPHENYLs (PCBs) A mixture of compounds containing the biphenyl structure with varying numbers (i.e., one to ten) and arrangements of chlorine atom attached.
  4. 4. Fully-Chlorinated PCB Molecule
  6. 6.  Polychlorinated biphenyls (PCBs) were widely used as dielectric and coolant fluids, for example in transformers, capacitors, and electric motors. Due to PCBs' environmental toxicity and classification as a persistent organic pollutant, PCB production was banned by the United States Congress in 1979 and by the Stockholm Convention on Persistent Organic Pollutants in 2001
  7. 7. Why Were PCBs Banned? • Persistent in the environment • Bioaccumulation & bioconcentration effects • Found in virtually all human fat tissue 􀂃 Humans 2300 ng/g 􀂃 Human Breast Milk 1200 ng/g
  8. 8. PHYSICAL AND CHEMICAL PROPERTIES OF PCBs PHYSICAL •Odorless • Colorless •Low vapor pressure •Viscous liquid or solid CHEMICAL Flame Retardant • Lipophilic (mix easily with oil or fat) • Very Stable •Low electrical conductivity
  9. 9. EFFEETS OF PCBs ACCUTE EFFECTS: No reports of effects in humans following acute (short-term) exposure to PCBs are available. Animal studies have reported acute effects on the liver, kidney, and central nervous system from oral exposure to PCBs. Acute animal tests in rats have shown PCBs to have moderate acute toxicity from oral exposure.
  10. 10. CHRONIC EFFECTS (No cancer):  EPA has not established a Reference Concentration for all PCB mixtures.  Chronic inhalation exposure of workers to PCBs has been reported to result in respiratory tract symptoms, such as cough and tightness of the chest, gastrointestinal effects including anorexia, weight loss, nausea, vomiting, and abdominal pain, mild liver effects, and effects on the skin and eyes, such as skin rashes, and eye irritation.
  11. 11. SIGNS
  12. 12. Reproductive/Developmental Effects:  Human studies are not conclusive on the reproductive effects of PCBs. One study of men who were occupationally exposed to PCBs showed no fertility abnormalities, while another study of men with low sperm counts found elevated levels of PCBs in the blood and an association between certain PCB compounds in semen and decreased sperm motility.
  13. 13. CANCER RISK:  Human studies provide inconclusive, yet suggestive evidence of an association between PCBs' exposure and liver cancer. Several studies have reported an increase in liver cancer among persons occupationally exposed to some PCB formulations. However, the studies are inconclusive due to confounding exposures and lack of exposure quantification.
  14. 14. CONT…  No animal inhalation studies are available on the health effects of PCBs. PCBs are absorbed through inhalation though, indicating that there may be concern for this route of exposure.  EPA has classified PCBs as a Group B2, probable human carcinogen.
  15. 15. POLYCYCLIC AROMATIC HYDROCARBONs (PAHs)  Polycyclic Aromatic Hydrocarbons (PAHs) are a group of chemicals that are formed during the burning of coal, oil, gas, garbage, tobacco or charbroiled meat.  PAHs occur naturally or can be man-made.
  16. 16. Common PAHs      Anthracene Benzo(a)pyrene Chrysene Fluorene Pyrene
  18. 18. Properties of PAHs  Colorless, white, or pale yellow-green solid  Evaporate quickly into the air when heated  Attach strongly to soil and other particles  Break down slowly  Do not dissolve easily in water  Do not burn easily
  19. 19. How do PAHs get in the Environment? PAHs are released to the environment through natural and man made processes. Man-made sources contribute far more PAHs to the environment than natural sources.
  20. 20. Man-made Sources        Burning of wood Vehicle exhaust Grilled/smoked foods Cigarette smoke Asphalt roads/Parking lots Roofing/coal tar products Agricultural burning
  21. 21. Natural Sources • Forest fire • Volcanoes
  22. 22. PAHs in the Environment  PAHs stick tightly to soil particles.  Some PAHs evaporate into the air from soil or surface waters.  PAHs in air settle to the ground where they are deposited on soil, plants, or in lakes and streams.  PAHs stay very close to the surface of the ground or move to lakes and streams by a process called erosion.  PAHs that enter lakes or streams settle to the bottom and are buried in sediments.
  23. 23. How can PAHs enter and leave your body? PAHs can One of the most common ways enter the body is through breathing contaminated air. PAHs get into your lungs when you breathe them. If you live near a hazardous waste site where PAHs are disposed, you are likely to breathe PAHs. If you eat or drink food and water contaminated with PAHs, you could be exposed.
  24. 24. Exposure to PAHs can also occur if your skin contacts PAH-contaminated soil or products like heavy oils, coal tar, roofing tar, or creosote. Creosote is an oily liquid found in coal tar and is used to preserve wood. Once in your body, PAHs can spread and target fat tissues. Target organs include the kidneys and liver. However, PAHs will leave your body through urine and feces in a matter of days.
  25. 25. EFFECTS ON LABORATORY ANIMALS  Tumors occur in some animals exposed for long periods of time.  PAHs have been shown to have an effect on the immune system of some animals.  EPA considers PAHs to be probable human carcinogens (cancercausing substances).
  27. 27. MEASUREMENTS IN AMBIENT AIR Sample and Analysis Approach PCBs Ambient air is drawn through a glass fiber filter and a polyurethane foam (PUF) adsorbent cartridge by means of a high volume sampler. The filter and PUF cartridge are returned to the laboratory and extracted using toluene. The extract is concentrated using the Kuderna-Danish technique, diluted with hexane, and cleaned up using column chromatography. The cleaned extract is then analyzed by high resolution gas chromatography/high resolution mass spectrometry. DETECTION LIMIT: 0.25-5000pg/m3
  28. 28. PAHs Ambient air is drawn through a glass fiber filter and polyurethane foam (PUF) or XAD-2 adsorbent cartridge by means of a high volume sampler. The filter and PUF cartridge are extracted using 10% diethyl ether. The extract is concentrated using Kuderna-Danish technique, diluted, and cleaned up using column chromatography. The cleaned extract is then analyzed by gas chromatography/mass spectrometry. DETECTION LIMIT: 0.5-500ng/m3
  29. 29. For more information Contact your state health or environmental department, or: Agency for Toxic Substances and Disease Registry Division of Toxicology 1600 Clifton Road, N.E., E-29 Atlanta, Georgia 30333