Plastic facts - What happens to a plastic bag when you throw it away?

Plastic facts

The world produces over 200 million tonnes of plastic each year. About half of this is used for packaging that becomes waste within a year. This accumulates in landfill and the problem is growing.

UK beaches contain on average 2000 pieces of litter for every kilometre.

80% of waste at sea comes from the land and up to 80% of that is plastic.

Most of this ends up in the sea through storm drains. The main sources of plastic are: bags, packaging and disposable products, industrial discharges, rubbish transportation, landfills, construction waste, and waste from commercial establishments and public venues.

It takes longer for the sun to break apart plastic in the sea than on land. Plastic pieces can attract and hold things like PCBs and DDT. PCBs are organic pollutants and have entered the environment through use and disposal. PCB’s are banned because they can cause cancer. DDT is an insecticide that was banned in the UK in 1984.

Over 1 million and 100 thousand marine mammals and turtles die every year from becoming entangled in or swallowing plastic.

Plastic bags

Defra (2003) estimates show that 8 billion lightweight plastic carrier bags are issued in the UK each year. That’s about 166 bags for each adult each year.

Some plastic bags are described as compostable and biodegradable the definitions of these properties of plastics.

Compostable bags

These bags can break down in a compost site to carbon dioxide, water, inorganic compounds, and biomass. The resulting humus is safe to use in the soil.

To be classified as compostable certain standards must be met such as the rate of biodegradation, maximum amount of material left at a specific point in time and for the material to have no harmful impact on the final compost or the composting process. All compostable plastic is therefore also biodegradable. The most commonly used standards for compostable plastic are the American standard ASTM #D6400-99, the European standard EN-13432 and DIN V-54900.

The important thing to remember with a compostable plastic bag is that when you can no longer use it (and you can re-use them!) then you need to compost what’s left.

Biodegradable

These materials will degrade from the action of naturally occurring micro-organisms, such as bacteria, fungi etc. Biodegradable material is not always compostable, as what is left over may be toxic and therefore cannot be used as compost. For biodegradation to take place the micro-organisms also need oxygen and moisture.

Things to consider when a bag is labelled 'biodegradable':

• Conditions have to be right for a bag to biodegrade. If the conditions aren't right; the bag won't biodegrade well. Conditions are generally not right in your bin; landfill sites; the local river; the sea or up a tree. It can take years for biodegradation to occur in a landfill, if it happens at all.
• If a bag biodegrades it may still leave a toxic residue.
• It is not recommended to mix 'biodegradable' plastic with 'normal' plastic. If biodegradable plastic is added to recyclable plastic, products made with this material could be weakened.
• Biodegradable bags are not the answer to environmental plastic bag litter because the conditions required for full biodegradation are not met.
• Biodegradable does not mean it is compostable.
  

Photo-degrade

This means to break down by the action of natural daylight. Plastic that can only be broken down in this way just gets smaller and smaller but still remains a plastic.

Degradable

Degrade just means to break something down. You can degrade something by tearing it up into smaller and smaller pieces. So, most things are degradable. All of the above are forms of degradation. On its own this term says nothing about how long it may take or what is left in the end. When it comes to plastic what may be left in the end are just lots of small pieces of plastic. So when you see this term on a product you need to know how it degrades.

Alternatives to plastic carrier bags

Corn starch bags

Bioplastic material based on plant derivatives. These bags are fully home compostable. Starch based bags are strong and waterproof. How long they last depends on their composition, additives and intended use and storage. Most of these alternatives have a greater or lesser content of plastic! It is very hard to find out the exact composition as the packaging world is extremely competetive and secretive about their 'recipes'.

Paper bags

Paper bags are heavier to transport and consume a lot of energy and resources especially water in manufacture (though recycled paper takes much less energy then virgin paper manufacture). It takes more than four times as much energy to manufacture a paper bag as it does to manufacture a plastic bag. However paper bags don’t cause littering or problems to wildlife in the same way as plastic. Buying paper bags made of 100% recycled paper helps to create a market for recycled paper which helps councils and other waste processors to sell waste paper.

Non woven bags

Not as long lasting as cotton or jute bags. Non woven reusable bags are made of polypropylene fibres which decompose and break down into microscopic inorganic particles which are neutral in the soil and do not affect groundwater.

They decompose over several months when subjected to humidity, rainwater and uv rays – elements found in all landfill sites.

Cotton bags

Cotton bags are a good alternative as they are strong, reusable, washable, mendable. They can be folded up and carried in pockets or handbag. They are available to buy in Coop supermarkets.

Jute bags