It is not however true. Bio-degradable plastic bags have now been dispensed by supermarkets for more than five years, but there is no evidence that people dispose more carelessly of them, and they have not been encouraged to do so. Pick up any piece of plastic litter and you are most unlikely to find the word “biodegradable” on it. An apple-core is obviously biodegradable, but a litter-lout could not tell the difference between an ordinary plastic bag and an oxo-biodegradable one.
It is absurd to think that such a person will take the trouble to read the label (if there is one) to see whether it is biodegradable, before deciding to throw it away.
In any event a lot of litter is accidentally released into the environment, without any conscious decision by anyone. But suppose for the sake of argument that 10% more were discarded. If 1,000 conventional and 1,100 oxo-biodegradable bags were left uncollected in the environment, 1,000 conventional bags would remain in the rivers, streets and fields for decades, but none of the oxo-biodegradable bags would be left at the end of the short life programmed into them at manufacture.
Education may have some effect, but there will always be people who will deliberately or accidentally discard their plastic waste. What will happen to all the plastic waste that will not be recycled or will not be incinerated, and instead will litter the countryside - would it not be better if the discarded plastic were all oxo-biodegradable?
Most governments will have heard of this type of plastic. It is often described as “bioplastics” “bio-based plastics” or “compostable plastics”. These plastics attracted public attention about ten years ago because they are made wholly or partly from vegetable resources such as corn starch, and were thought to be “renewable.”
However, they are not really “renewable” because large amounts of fossil-fuels are burned and CO2 emitted in the production process. Many governments wish to reduce oil imports but they will not do so by preferring hydro-biodegradable or “compostable” plastic. In June 2009 Germany’s Institute for Energy and Environmental Research concluded that compostable plastics have a worse Life-cycle Analysis than oil-based plastics. The British Government published a similar study in February 2011which came to the same conclusion.
Further, "compostable” plastics:
- cannot be recycled with normal plastic,
- could put local producers out of business as they are up to 400% more expensive than normal plastic, and the film cannot easily be made with existing machinery,
- are designed to be collected and taken to a composting factory, and do not therefore address the problem of plastic which gets into the environment and cannot realistically be collected,
- emit methane deep in landfill,
- compete for land and water resources with food production (except for a small proportion made from vegetable wastes), and there will always be very limited availability,
- are not useful even for compost. This is because the Standards for compostable plastic require it to convert itself into CO2 gas within 180 days. This contributes to climate change but does nothing for the quality of the soil.
The packaging manager of Tesco (Britain’s largest supermarket) said on 20th October 2009 that the supermarket “does not see the value in packaging that can only be industrially composted” and that “city authorities do not want it, as it can contaminate existing recycling schemes."
Briefing for Governments on Oxo-biodegradable Plastic