The American Society of Plastics Industry developed a standard marking code to help consumers identify and sort the main types of plastic.

The main types of plastics are:

	Polyethylene terephthalate - Fizzy drink bottles and oven-ready meal trays
	High-density polyethylene - Bottles for milk and washing-up liquids.
	Polyvinyl chloride - Food trays, cling film, bottles for squash, mineral water and shampoo
	Low density polyethylene - Carrier bags and bin liners.
	Polypropylene - Margarine tubs, microwaveable meal trays.
	Polystyrene - Yoghurt pots, foam meat or fish trays, hamburger boxes and egg cartons, vending cups, plastic cutlery, protective packaging for electronic goods and toys
	Any other plastics that do not fall into any of the above categories.  An example is melamine, which is often used in plastic plates and cups.

If you look on the plastics products you buy, you should spot the little symbol.

These are oil based and either eventually break down or disperse in to smaller fragments. These may then potentially biodegrade or break down further to reduce the material to water, CO2, biomass (plant matter) and trace elements.

These should break down cleanly, in a defined time period, to form simple molecules found in the environment such as carbon dioxide and water.

The predominant mechanism which decomposes biodegradable plastics is the action of micro-organisms which produces:

• carbon dioxide;
• methane;
• water;
• inorganic compounds; or
• biomass.

These are a subset of biodegradable plastics which must demonstrate that they biodegrade and disintegrate completely in a compost bin or system during the 3-4 months composting process.

Biodegradable and degradable plastics will not degrade effectively in a landfill site and could potentially hinder the quality of recycled plastic if they enter a conventional plastics recycling system.