University of Bristol
Wellcome Trust
Recommended by:
Society of Biology
PEEP for Physics & Ethics at GCSE


Facts and figures

Pollutant Source Entry pathway Biological effect Figures

CFC’s (Chlorofluorcarbons)
Spray cans

Coolants in fridges and propellants in aerosol cans.

Slowly rise into the ozone layer in the stratosphere (15-35kms above the ground)

Depletion of the ozone layer leading to more harmful ultraviolet (UV) radiation reaching the ground. Harmful to humans and damage to producers in food chains e.g. kills plankton

CFC levels peaked in 1990. They have a long life in the atmosphere and recovery will only take place in the middle of the 21 st century.

Sulphur dioxide
chimneys bleching smoke

Combustion of fuels containing sulphur.

May remain in gaseous form or dissolve in rainwater to form sulphurous acids

Effects on human health (asthmatics). Damage to plant growth as seen by destruction of some forests.

70% of emissions come from coal-fired power stations. UK in 2002 produced 1002 thousand tonnes of Sulphur Dioxide.

PCB’s (Polychlorinated biphenols)
Decorators paint brush

Found in protective sealants for wood and metal. Used as a coolant in electrical transformers.

PCB’s are given off during incineration.

Layer on surface of water.

Concentrate in marine mammal fat and oily fish. Can be toxic at the top of the food chain.

PCB sales were virtually stopped in 1973. It is estimated that 31% of PCB’s ever produced are free in the environment – 1.2 million tonnes.

Broad bean pods

Nitrate fertilisers

Leaching into waterways

Eutrophication and human health hazard due to high nitrate levels in drinking water.

31% of rivers in England have nitrate levels higher than 30mg nitrates/litre. Legal drinking level is 50mg nitrates/litre

Crop spraying

Runoff from agricultural land, spraying.

Spray drifting. Pesticides into waterways

Bioaccumulation in food chains – toxic to the higher consumer levels.

 UK persticide figures

Carbon Dioxide
Car exhaust pipe

Released from the combustion of fossil fuels.

Enters atmosphere.

Increases the greenhouse effect leading to global warming and climate change

In 2003, UK produced 550 million tonnes of Carbon Dioxide.

Heavy metals (e.g. lead and mercury)

Direct discharge of leakage.


Enter waterways and long-term contamination of soils.

Directly toxic or accumulate in food chains.

Mercury is used in gold extraction. Lakes near gold mines (Brazil, Indonesia) have fish within 200kms that have mercury levels which make them unfit to eat.

Organic chemicals (oil)
Shipwrecked oil tanker

Discharge and leakage.

Into waterways

Directly toxic to some organisms. Kills fish and waterfowl. Disruption of food chains.

 Biggest oil spill in 25 years:

Open cast mining

Mining, nuclear power generation, weapons testing.

Enters the atmosphere, contaminates soil.

Causes cancer and genetic defects.

In the UK, 85% of radiation comes from natural radiation sources. Of the 15% artificial radiation, most comes from medical sources.

Organic waste
A pipe discharges pollution into a river

Sewage, biodegradable industrial waste, agricultural waste (slurry).

Released into waterways.

Discharge from sewage farms.

Raw sewage is toxic to many organisms, pathogens affecting human health. Treated sewage (high in nitrates) may cause eutrophication.

In England and Wales, discharge of effluent into rivers  needs permission – there are over 100,000 consents in place.


 Agricultural Pollution


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