A man collects plastic bottles to sell for recycling, in a landfill of Managua, Nicaragua, on January 11, 2013. Photo: Getty Images
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Scientists buried biodegradeable plastics for three years, found it doesn't degrade

Common method of making plastic "biodegradeable" seems to be useless, in some types.

Gardeners beware - those "compostable" bin bags might not so readily turn into soil. A study published in Environmental Science & Technology has found that many common biodegradeable plastics, aren't - and that recycling is a much better bet.

There are typically two ways to make plastics degrade faster than they otherwise would: either add stuff to them to make them break down faster, or make them out of biological materials like vegetable oil or corn starch. The researchers, from Michigan State University, were specifically interested in the first set, and did what has to be done when testing how fast something rots - they buried a bunch of different plastics, for three years, and then dug them up again to see what had happened. The results don't bode well for the efficacy of additives.

Typically, plastics made from petroleum can take hundreds of years to decompose, yet getting precise estimates for the timeframes involved can be difficult. After all, most modern plastics haven't been around anything like the amount of time we think they'll take to break down - and the thing that makes plastics so useful as packaging, that they're unappetising to bacteria, makes them also an environmental terror. It's not just about plastic bags caught in trees; the plastics that form the Great Pacific Garbage Patch, a vast gyre of debris, form an ongoing natural disaster that is entirely human-made.

Recycling is, of course, one option to prevent the problem in the first place; another is making plastics biodegradeable, so that they either break down into other, harmless molecules, or into something small enough that bacteria might consider it food. But designing material that is able to maintain its strength and durability during everyday use while also breaking down when exposed to sunlight is a challenge, as is creating a material that breaks down in both landfills (airless, warm, dark, compressed) and stuck in a hedge or river (light, airy, varying temperature).

For this study, the researchers looked at two specific types of plastic - polyethelene, and polyethylene terephthalate, both of which are extremely ubiquitous as packaging material, especially for containers like plastic bottles - with five different additives (that supposedly improve biodegradeability) in three different environments: buried with oxygen (as in compost); buried without oxygen (as in a landfill); and simply bured in soil.

No matter the additive, and no matter the environment, they didn't find anything that appeared to have made the plastics decompose quicker than without. In a statement, the authors recommend "the proper management of waste plastics" instead - which means, for now, if you want to do the right thing by the environment, either use something known to degrade properly, recycle it before it gets into the ground, or (and possibly the easiest option in many situations) not using plastic at all in the first place.

Ian Steadman is a staff science and technology writer at the New Statesman. He is on Twitter as @iansteadman.

Photo: Getty Images
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Autumn Statement 2015: George Osborne abandons his target

How will George Osborne close the deficit after his U-Turns? Answer: he won't, of course. 

“Good governments U-Turn, and U-Turn frequently.” That’s Andrew Adonis’ maxim, and George Osborne borrowed heavily from him today, delivering two big U-Turns, on tax credits and on police funding. There will be no cuts to tax credits or to the police.

The Office for Budget Responsibility estimates that, in total, the government gave away £6.2 billion next year, more than half of which is the reverse to tax credits.

Osborne claims that he will still deliver his planned £12bn reduction in welfare. But, as I’ve written before, without cutting tax credits, it’s difficult to see how you can get £12bn out of the welfare bill. Here’s the OBR’s chart of welfare spending:

The government has already promised to protect child benefit and pension spending – in fact, it actually increased pensioner spending today. So all that’s left is tax credits. If the government is not going to cut them, where’s the £12bn come from?

A bit of clever accounting today got Osborne out of his hole. The Universal Credit, once it comes in in full, will replace tax credits anyway, allowing him to describe his U-Turn as a delay, not a full retreat. But the reality – as the Treasury has admitted privately for some time – is that the Universal Credit will never be wholly implemented. The pilot schemes – one of which, in Hammersmith, I have visited myself – are little more than Potemkin set-ups. Iain Duncan Smith’s Universal Credit will never be rolled out in full. The savings from switching from tax credits to Universal Credit will never materialise.

The £12bn is smaller, too, than it was this time last week. Instead of cutting £12bn from the welfare budget by 2017-8, the government will instead cut £12bn by the end of the parliament – a much smaller task.

That’s not to say that the cuts to departmental spending and welfare will be painless – far from it. Employment Support Allowance – what used to be called incapacity benefit and severe disablement benefit – will be cut down to the level of Jobseekers’ Allowance, while the government will erect further hurdles to claimants. Cuts to departmental spending will mean a further reduction in the numbers of public sector workers.  But it will be some way short of the reductions in welfare spending required to hit Osborne’s deficit reduction timetable.

So, where’s the money coming from? The answer is nowhere. What we'll instead get is five more years of the same: increasing household debt, austerity largely concentrated on the poorest, and yet more borrowing. As the last five years proved, the Conservatives don’t need to close the deficit to be re-elected. In fact, it may be that having the need to “finish the job” as a stick to beat Labour with actually helped the Tories in May. They have neither an economic imperative nor a political one to close the deficit. 

Stephen Bush is editor of the Staggers, the New Statesman’s political blog.