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Summary TOX20303

- TOX20303
- Ivonne Rietjens
- 2016 - 2017
- Wageningen University (Wageningen University, Wageningen)
- Voeding en Gezondheid
290 Flashcards & Notes
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A snapshot of the summary - TOX20303

  • College 1 + 2

  • Rachel Carson 'Silent Spring' (boek) 1962
    Alles was dood gegaan en het gebruik van DDT was uit de hand gelopen. Silent spring niet veel vogels en insecten...

    challenged the notion that man was destined to control nature 
  • Exposure assessment: route & site of exposure
    • Gastrointestinal tract (oral)
    • lungs (inhalation)
    • skin (dermal)
    • injections
  • Exposure assessment: duration and frequency
    Acute: <24 hours, single dose 
    subacute: 1 month or less
    subchronic: 1-3 months 
    chronic: >3

    effect varies with dose & exposure regimen 
  • Calculate if actual exposure is safe: (margin of safety)

    Margin of safety 

    exception: initiating genotoxic carcinogens: only risk assessment (no safety, priority setting)
  • Oxidative stress: catalyses Haber-weiss reaction
    Increases the impact of superoxide anions O2 *- and H2O2 by the formation of reactive hydroxyl radicals *OH

    'makes it more toxic'
  • College 3 + 4

  • Absorption: passing cell membranes via
    • Phospholipid
    • intergral proteins
    • cholesterol 
    • ion channel 
    • ligand 
  • Passive transport is influenced by:
    - Water solubility:

          Hydrophobic chemicals --> passive diffusion
          Hydrophilic chemicals --> passive filtration (aqua pores)

    - Ionization:

           Low pH (< pka) --> chemical in non-ionized form --> chemical is taken up in stomach
           High pH (> pka) --> chemical in ionized form --> chemical is taken up in small intestine

    - Blood flow: if molecules are not taken away by bloodflow
           Concentration of the chemical = concentration blood
  • Uneven distribution of a chemical
    Toxicity in a specific tissue: water soluble chemical + albumin --> stay in fat tissue
  • Blood brain barrier
    Active transport needed for the uptake of molecules in the brain:
    - Thight junctions
    - No fenestrea
    - Low protein content
    - ATP is needed
  • College 5 + 6

  • Not water soluble chemicals
    Need biotransformation in order to be excreted via urine/bile
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