Properties of Pollutants

Properties of Pollutants

1. Toxicity

   • A measure of how poisonous a substance is, usually caused by enzyme inhibition
   • If biological reactions controlled by proteins and enzymes cannot take place then the affected cells may malfunction

2. Specificity

   • A measure of differing toxicities of a substance on different organisms
   • A specific substance is very toxic to some organisms but much less toxic to ohers

3. Persistance

   • A measure of the rate at which a material breaks down and therefore the length of time it remains in the environment
   • Does not apply to elements that cannot break down under normal environmental conditions - non degradable
   • CFCs and DDT are good examples of persistent chemicals - they can take decades to break down

4. Biodegradability

   • The ease with which a material is broken down by living organisms, usually bacteria

5. Mobility

   • A measure of how easily a material moves through the environment
   • Highly mobile pollutants can travel longer distances, causing problems over larger areas, although they may also be diluted and become less locally harmful

6. Solubility

   • The ease with which the molecules of a material separate and disperse into a liquid
     • These materials are very mobile in the hydrosphere - lakes, rivers, oceans, etc
   • Liposolubility - A measure of how easily a substance dissolves in fats and oils
     • These materials (e.g. PCBs, mecury, lead, organochlorine insecticides) be stored for long periods of time in living organism

7. Bioaccumulation

   • The increase in concentration of a substance in living tissue
   • Chronic exposure to small doses over long periods of time may result in bioaccumulation. This occurs most often with liposolubles.

8. Biomagnification

   • The progressive bioaccumulation of a material along a food chain

9. Synergism

   • The process where the presence of two materials produces a greater effect that the sum of their individual effects
   • Synergism is difficult to predict and although there are some known examples (zinc and cadmium) it is impossible to test out all possible combinations to which we are exposed

10. Mutagenicity

    • A mutagen is a material that can cause changes in DNA structure
    • If gametes are affected then babies produced may have birth abnormalities that could be passed on to future generations

11. Carcinogenicity

    • A carcinogen is a mutagen that causes body cells to start to multiply in an uncontrolled way (cancer)

12. Teratogenicity

    • A substance that interferes with gene function in a growing embryo so that a non-inherited birth abnormality is produced

13. Primary/Secondary

    • Primary pollutants are pollutants released from direct human activity e.g. carbon dioxide from burning fossil fuels
    • Secondary pollutants are pollutants produced through chemical reactions between primary pollutants e.g. PANs