2. What is pollution? “Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms” “Pollution is contamination of the natural environment with harmful substances often as a consequence of human activities.” “ A Pollutant is something that when released into the environment causes some harm or alters the environment in a negative way.”
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4. Sources of pollution. FUGITIVE Fugitive emissions are usually gases that escape unnoticed – unintended or irregular releases of gas, usually leaks from pressurized equipment.
5. Pollution Sinks A place or process that removes, stores or absorbs the pollutant. Wetlands are a pollutant sink for heavy metals and other materials. Atmospheric carbon dioxide dissolves in sea and is stored in organic matter such as plants and vegetation.
7. Toxicity The measure of harm (death or illness) a substance can cause in humans and other living things. Toxicity is defined as acute and chronic respectively this refers to single and repetitive exposure.
8. LD50 Is the term used to describe the dose of a substance that is sufficient to kill a percentage (50%) of the specified test animal within a specified period. The smaller the LD50 dose the more toxic a substance is. The lethal dose figures refer to acute toxicity and do not give an indicator of cumulative effects over time.
9. Persistence A property of a pollutant which relates to the time that the pollutant takes to break down. Substances that are not easily broken down are said to be persistent. A pollutant is degradable if it breaks down with sunlight, soil, water or in chemical reactions.
10. Dispersal and Transport The way that a pollutant is spread or moves around the environment. Dispersal can be airborne, water borne or in soils.
11. Exposure The degree of time spent near or in contact with the pollutant. The level of exposure is related to the properties of the pollutant.
12. Pathways Inhalation When toxicants make their way into the human body through the lungs. Ingestion When toxicants make their way into the human body through the stomach. Absorption. When toxicants make their way into the human body through the skin.
13. Types of exposure and toxicity. Chronic Exposure/Chronic Toxicity Repeated exposure and/or absorption over a long period of time. Acute Exposure/Acute Toxicity A single, severe case of exposure, absorption and harm caused.
14. Synergistic action An interaction between two or more individual compounds that produces an effect upon the body (or an organism) GREATER than either of the substances alone would have produced. When the combined result is greater than the sum of it’s parts. Example: Smog – combinations of pollutants.
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16. Volatile Organic Compounds (VOC’s) Volatile organic compounds are emitted as gases from certain solids or liquids. They are usually the gaseous vapours (fumes) from paints and fuels, such as petrol or other hydrocarbons. They can be naturally occurring or man-made. VOCs are typically not acutely toxic but have chronic effects. Because the concentrations are usually low and the symptoms slow to develop, analysis of VOCs and their effects is a demanding area.
