Toxins and Contaminants Flashcards
Define a contaminant.
It is a chemical or a chemical, which present at a concentration, that will cause harm to humans or the environment and are usually caused by humans.
What is the problem at the moment?
1) There are 7 million recognised chemicals that are in existence.
2) 80,000 of them are in common use worldwide.
3) Toxicity Rarely Understood
4) Contamination is global
How to can we eliminate all contaminants?
It is impossible to eliminate all contaminants we need a risk based decision making process and there are a plethora of legal instruments for doing this which involve source, pathway and receptor (human, ecological or physical).
How do we look at risks in people or in animals?
It is through the NOEL (No effect level).
What does LOEL stand for?
Lowest effect level.
What is EC 50?
Effect concentration 50 and it affects half the test population.
Sketch the dose response curve labelling all the features.
See notes.
What are the 4 key factors in a risk assessment?
1) Hazard identification
2) Hazard assessment
3) Risk elimination
4) Risk evaluation
What is contamination central to?
Sustainability in which there is a strict regulation.
Name 4 historic areas where there was mass pollution.
1) Romans
2) 19th century industrialisation
3) 20th century chemical industry
4) 21st century pharmaceuticals
Define a contaminated land.
It is land which contains substances that, when present in sufficient quantity or concentrations, are likely to cause harm directly or indirectly to humans, the environment or other targets such as construction materials.
What doe contaminated land lead to?
Contaminated groundwater.
What is important about the construction of landfill?
That is done correctly, otherwise you would have contaminated groundwater.
Give two example where groundwater may be contaminated.
1) Leaking petrol storage tanks
2) Dry cleaners- Tetrachlorethene, people said just let it evaporate away however it is very dense.
What mean contaminated groundwater will get worse?
Plumes- vertical body of a fluid moving through another.
Define a micro-pollutant.
chemicals that have a serious ecological effect at low physical concentrations.
State an important micro-pollutant.
The human contraceptive pill: occurs in ng concentrations, shown to be the major cause of widespread feminisation of fish and other marine animals.
What ends up in wastewater?
Anything we take into our bodies will appear in wastewater for example if you take cocaine there will be a proportion of mg 100p^-1 day going into the wastewater contaminating it.
What are the two classes of contaminants?
1) Organic pollutant- carbon based, often combined with chlorine, with organic pollutant structure is everything, PAH benzo pyrene carcinogenic by pyrene is not carcinogenic.
2) Inorganic pollutant- are things found naturally but because of human production of goods have been altered to drastically increase the amount of them in the environment.
State 7 inorganic pollutants starting from ones which disrupt the ecosystem to ones which disrupt metabolism.
1) Carbon dioxide
2) Salnification
3) Oxides of N and S- accidfication
4) Eutrophication
5) Acid mine waters
6) Radioactivity
7) “Heavy metal” contamination
Define bioaccumulation.
It is the gradual accumulation of substances, such as pesticides, or other chemicals in an organism.
Do all chemicals degrade?
No
Name a chemical that doesn’t degrade?
DDT
What is DDT?
Semi-volatile organochlorinated compounds.
