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Polychlorinated biphenyls (PCBs) and human health


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PCBs are detrimental to human and environmental health. (Review)
Water Quality and Health Presentation. University of Winnipeg.

Published in: Science
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Polychlorinated biphenyls (PCBs) and human health

  2. 2. What are PCBs?  Polychlorinated biphenyls  Persistent organic pollutant  209 PCB congeners  Fat soluble  No known taste/smell Figure 1. Chemical structure of PCBs. 1929: PCBs first manufactured. 1966: PCBs first detected in the Great Lakes. 1977: Import, manufacture and sale banned in Canada. 1985: Illegal to release PCBs to the environment. 1988: Storage of PCBs becomes regulated.
  3. 3. Where do PCBs come from?  Transformers and capacitors  Electrical equipment (voltage regulators, switches, re-closers, bushings, electromagnets)  Oil used in motors and hydraulic systems  Oil based paint  Caulking  Fluorescent light ballasts  Cable insulation  Adhesives and tapes  Old electrical devices or appliances containing PCB capacitors  Plastics  Thermal insulation material including fiberglass, felt, foam, and cork  Carbonless copy paper  Floor finish (EPA, 2016) Contamination from PCBs has been caused by accidental releases, careless disposal practices and leaks from industrial facilities or chemical waste-water disposal sites.
  4. 4. Commercial PCBs: Aroclor  Lower chlorinated biphenyls (Aroclor 1242) has a half life of 2.6 years.  Higher chlorinated biphenyls (Aroclor 1254) has a half life of 4.6 years.  Less-chlorinated congeners more readily metabolized then highly chlorinated congeners.  Highly chlorinated congeners remain in body longer than low-chlorinated PCBs.  Thus, highly chlorinated congeners bioconcentrate in adipose tissue. The only North American producer of PCBs was Monsanto until it was banned in 1977. Currently dealing with 6 lawsuits.
  5. 5. PCBs in the environment.  Highly chlorinated PCBs more resistant to degradation.  Does not readily break down in the environment.  Found around the world and contaminates food, air, soil and water.  Incorporated into plant material and food crops.  Bioaccumulates in fish and animal tissues.  Distributed to remote locations by air currents. Figure 2. Biomagnification of PCBs in Great Lakes food chain. EPA DW Guideline: 0.0005 ppm FDA Food Guideline: 0.2-3 ppm (2 ppm in fish).
  6. 6. Human Exposure to PCBs  All humans have PCBs in their body.  Average Daily Consumption is <0.5 micrograms.  PCBs are absorbed through ingestion, inhalation, and dermal exposure, after which they are transported through the circulation.  Primary Exposure Route: Accidental exposure  Accidental releases, consumption of contaminated foods, living near incinerators or PCB disposal facilities  Workplace exposure  Servicing old electrical equipment, transporting PCBs to storage/destruction facilities, working in storage/destruction facilities.
  7. 7. Adverse Health Effects of PCBs  Mechanism of Toxicity  PCBs bind to nucleophilic macromolecules (protein, DNA, RNA) and induce DNA strand breaks and DNA repair.  Target Organs  Skin, eyes, liver, reproductive systems, other.  Health Effects  Chloracne, cumulative liver damage, probable human carcinogen  Symptoms  Eye irritation, chloracne, liver damage, reproductive effects, dry skin, redness, headache, numbness.
  8. 8. Adverse Health Effects of PCBs  Carcinogenic Effects  Every commercial PCB mixture tested caused cancer.  Increases in rare liver cancers and malignant melanoma  Immune Effects  Significant decrease in size of thymus gland  Reduced immune system response.  Decreased IgA and IgM antibody levels  Decreased monocyte, granulocyte, and natural killer cell count.  Neurological Effects  Deficits in neurological development (effected visual recognition, short and long term memory and learning)  Reproductive Effects  Reduced birth weight, conception rates, and live birth rates  Accumulation in breast milk  Neurobehavioral/developmental deficits in newborns exposed to PCBs in utero.  Reduced sperm counts  Endocrine Effects  Decreased thyroid hormone levels (thyroxine and triiodothyronine) (EPA, 2016).
  9. 9. Adverse Health Effects of PCBs  Mass PCB poisoning caused by consumption of PCB contaminated cooking oil.  Western Japan 1968 - Yushō disease – average PCB intake: 633 mg  Taiwan 1979 – Yu-cheng disease – average PCB intake : 973 mg  Increased eye discharge, pigmentation of nails, skin and mucous membranes, acneform eruptions, weakness (Masuda, 1985).
  10. 10. How to Protect Yourself? • Choose plain food packaging that uses less inks and dyes. • Install activated carbon filter • Don’t rinse chemicals, solvents, oil, paints, etc. down your home drains or storm-water drains. • Be aware of fish consumption advisories since PCBs can bio-accumulate in them. Allow fatty tissue to drip away when grilling/cooking.
  11. 11. References Environment and Climate Change Canada. 2014. Polychlorinated biphenyls (PCBs). Web. 29 March 2015. Retrieved from Environmental Protection Agency. 2016. Polychlorinated biphenyls (PCBs). Web. 29 March 2015. Retrieved from Health Canada. 2005. PCBs – It’s your health. Web. 29 March 2015. Retrieved from dgapcr/pdf/iyh-vsv/environ/pcb-bpc-eng.pdf Masuda, Y. (1985). Health status of Japanese and Taiwanese after exposure to contaminated rice oil. Environmental Health Perspectives, 60, 321–325. US Department of Health and Human Services, 2014. Agency for toxic substances and disease registry. Case studies in environmental medicine: Polychlorinated biphenyls (PCBs) toxicity.