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Understanding Chlorinated Organics: Properties, Uses, and Environmental Impact

Chlorinated organics are characterized by strong C-Cl bonds, making them stable and persistent in the environment. While non-polar and fat-soluble, these compounds may interfere with metabolic processes and can serve as pesticides, posing risks to non-target organisms. Notable chlorinated compounds include DDT and PCBs, which have historical significance in agriculture and industry but are now associated with severe health issues and environmental harm. Understanding their properties is crucial for managing their risks in modern applications.

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Understanding Chlorinated Organics: Properties, Uses, and Environmental Impact

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  1. Chlorinated Organics

  2. General Properties/Action • The C-Cl bond is very strong and does not easily break down • Persistence in the environment/organism • Non-polar • Not water soluble, but fat soluble • May interfere with metabolism • Can be useful as a pesticide • Can be problem for non-target organism • May affect nervous system

  3. DDT • Early synthetic pesticide – first used large-scale in WWII to control insects/lice • Thought of as a “Wonder Chemical” • Highly exposed soldiers complained of aching joints, tremors and depression • Widely used on crops with little regard for recommended dose rates • Thought to cause thin egg shells in birds • Banned (NA) in early 1970s

  4. PCBs • Poly Chlorinated Biphenyls • Over 200 possible compounds • First synthesized in 1880s, commercial use started in 1929 • Oil in electrical transformers, Painted on hydro poles, Plasticizers, De-inking fluids, Carbon-less copy paper, Cosmetics, Paints • Long term exposure is highest concern • Chloracne, general fatigue, headaches, joint pain

  5. Dioxins • 75 different possibilities • No known use; never intentionally produced • A possible contaminant in PCBs and a few other chemicals • By-product of paper bleaching, (now-banned) 2,4,5-T manufacture, burning some plastics (Saran) • Some spectacular disasters • Agent Orange • Times Beach, Missouri • Seveso, Italy • Milk cartons, coffee filters, diapers, napkins

  6. Dioxins, part 2 • Media: “deadly dioxin”, “most toxic substance known” • It is toxic, but other things are more toxic • Long-term low-dose exposure: • Chloracne • Birth defects • Immune function

  7. ChloroFluoroCarbons (CFCs) • Another “Wonder Chemical” • Non-toxic, non-flammable, cheap, easy to make • Used as refrigerants, foam blowing agents, circuitry cleaners, aerosol propellants • Allowed for safe refrigeration in homes • Once released into the atmosphere, reacts with ozone to cause depletion

  8. Trihalomethane • Trichloromethane = chloroform • Used in the production of Teflon • Naturally produced by some seaweeds • By-product of chlorine treatment of water • Levels present are very low – minimal risk

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