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Biodegradable is not my bag (May08)

Chuck away plastic and it lasts forever. That doesn’t sound great, particularly for things that are only useful for hours at best – seconds at worst. And if that plastic ends up littering the hedgerows or floating around in the oceans it’s not only an eyesore but can be damaging to wildlife too.

So, many people think it would make much more sense if these plastics were biodegradable and rotted away like a leaf or an apple core. Well, actually no it wouldn’t. And here’s why.

First it’s helpful to understand that there are two types of degradable plastic. The first is known as ‘hydro-biodegradable’ plastics. They’re generally made from crops, for example corn or potatoes, and will break down in moist conditions. The second are ‘oxy-biodegradable’ plastics, which are just like any other plastic but include a chemical additive that means it disintegrates over a period of time, when exposed to air and light.

Most of the rubbish we throw away ends up in landfill sites – great holes in the ground, filled with human detritus. One of our problems is that we’re filling up the holes we have and are running out of space for new ones.

But, it may surprise you to hear that there’s legislation in place restricting the amount of biodegradable waste going to landfill. The main reason for this is that rotting materials produce carbon dioxide and methane – greenhouse gases that we’re trying to reduce. So, bizarrely, if plastics end up in land fill, it’s better if they do stick around for thousands of years, locking away their global warming emissions.

Another thing to consider is that the conditions in land-fill sites often mean that even waste that’s supposed to rot doesn’t – and that applies to biodegradable plastics too. So, even if it was desirable, it may not happen! Garbologists – strange people who analyse waste – have been able to find perfectly readable newspapers from decades ago buried in amongst all the other stuff.

OK, so wouldn’t biodegradability be better for plastics thrown away as litter? Probably not. Oxy-biodegradable plastics will disappear over a period of 2-3 years in optimum conditions – that means being exposed to light and air. In the sea they’d take considerably longer because of the cold and wet. And the worrying thing about them is that the fact they’re biodegradable makes people think it’s OK to chuck the plastic litter out of a car window or off the side of a boat – where it will have plenty of time to wreak havoc with birds, whales or fish.

The perfect solution, you might think, is for biodegradable plastic to be composted. Surprisingly, that doesn’t really stack up either. Most of it actually can’t be composted in home systems – they simply won’t break down unless it actually says ‘compostable’ on the pack. Oxy-biodegradable plastics don’t even deteriorate in industrial composting systems and hydro-biodegradable plastics take five times longer to do so than household food waste. This means that if they’re in the system you need more equipment, more space and more time.

But probably the real killer is public confusion over biodegradability. Apparently, it gets treated like any other plastic – most gets sent to landfill sites and some to recycling. And in recycling systems there’s a significant disadvantage because its inclusion can contaminate the whole batch of recyclable plastics, which means it all ends up being dumped.

So, when I saw a plastic bag on the train last week saying that it was ‘environmentally friendly’ because it was ‘biodegradable’, I was unimpressed. I thought that it was complete rubbish in every sense of the word.

Don’t despair, there are things you can do. The first is to reduce the amount of waste your produce in the first place – refuse a bag and take your own. If you do want or need a bag the best option is to go for one made from recycled plastic. See the video and leaflet I’ve written for Marks & Spencer.

This blog was originally published on Telegraph online 

 

 

5 thoughts on “Biodegradable is not my bag (May08)

  1. pelmhirst says:

    I deal with biodegradable plastics and there are a few flaws in your argument. oxo biodegradable plastics can be good however there are few international standards controlling them so sometimes they do not live up to their promises. They are recyclable before they start to degrade (just like standard plastic) however once they are disposed of many formulas will degrade within a couple months (i.e. epi’s formula). If they do go to the landfill however they will break down eventually regardless of what conditions they are in. New formulas can biodegrade in a couple years while sitting on a dry store shelf. Also these bags do not produce methane for the majority of their break down since most of the plastic is degraded then at the end it is consumed by microbes which causes it to biodegrade and produce a little bit of methane. Starch bags are also good however unlike oxo ones, they cannot be recycled and produce more methane on degradation.

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  3. Anonymous says:

    Oxo biodegradable…. according to the Biodegradable Products Institute (www.bpi.com) are not really biodegradable and should not be labeled and marketed as such.

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