ETOX – LSN 11: Environmental Fate, Persistence, and Biodegradation, Pt 1

Environmental Fate, Persistence, and Biodegradation, Part 1

Environmental Fate of Chemicals

  • Chemicals and synthetic products in the environment:

    • Do they disappear/degrade, or do they persist?

Chemical Persistence

  • Definition (ICCA, 2001): The ability of a chemical to stay unchanged in the environment for a long period of time.

  • Definition (ECETOC): A persistent substance is resistant to abiotic and/or biotic degradation under both aerobic and anaerobic conditions.

  • Examples of Persistent Chemicals: PBTs (Persistent, Bioaccumulative, and Toxic substances), POPs (Persistent Organic Pollutants), PFCs (Polyfluorinated Compounds), PCBs (Polychlorinated Biphenyls).

  • Measurement: Persistence can be measured.

  • Persistent Organohalogen Compounds:

    • Possess inherent physicochemical properties that make them persistent.

    • Often bioaccumulate in the environment.

    • Polychlorinated compounds: PCBs and dioxins (e.g., insecticide DDT).

    • Polyfluorinated compounds (PFCs): E.g., water-repelling coatings like Teflon®\textregistered.

    • Polybrominated compounds (PBCs): PBBs and PBDEs (e.g., flame retardant Tetrabromobisphenol A).

Specific Persistent Organic Pollutants (POPs)

Polychlorinated Biphenyls (PCBs)

  • Introduction: Introduced in the 19401940s.

  • Broad Range of Applications:

    • Additives in plastics, adhesives, paints.

    • Lubricants.

    • Hydraulic liquids.

    • Heat transfer fluids.

    • Insecticides (DDT, chlordane, HCH).

  • Bioaccumulation: Highlighted in Rachel Carson's