Ground zero

There is an undeniably comforting image associated with degradable plastics that allows the guilt of consumerism to vanish into the ground like so much dirty water. Retailers adopting the latest degradable solutions under the premise of 'environmental awareness' are certainly keen to have us believe degradable plastics will deliver us from a world of encroaching landfill.

But are consumers being misled? Does the argument for degradable plastics fall to pieces when exposed to the reality of waste management. And does the technology really work? Or is cynicism and vested interest blocking the path for future packaging waste solutions?

Unusually for industry bodies with different agendas to promote there is a general agreement that some tough questions need to be asked of degradable plastics.

In the first instance, industry takes issue with the way they are marketed as an environmental solution to landfill reduction.

By 2010 biodegradable municipal waste is to be reduced by a hefty 75% of that produced in 1995, with further targets set to 2020.

It is estimated 60% of municipal waste is bio-degrade-able – that makes reductions to be made of around 3.2M tonnes each year to meet the first target. In this sense, degradable plastics are something of a solution looking for a problem says Jane Bickerstaffe director of Incpen.

"Above all the issue is one of sustainability," says Jim Pugh, chief executive of PIFA (Packaging and Industrial Films Association). "Everyone who knows anything about environmental care will understand that degradeable plastics involves the deliberate creation of a material that will go to waste. This contradicts the first principle of sustainability which is to ensure that valuable earth resources are not wasted but re-used, recovered or recycled."

The very fact that some degradable plastics are claimed to work in landfill is met with contention. "Landfill doesn't create an ambience to degrade. There is no free flow of moisture or oxygen which is normally required by degradable materials," says Mr Pugh.

"It is widely reported that even naturally degradable materials such as newspapers or carrots will remain in virtually their original state 20 years on."

Scepticism surrounds solutions claimed not to rely on air and moisture to degrade in landfill. PIFA is reluctant to comment on specific products, but it believes there is currently insufficient evidence that conditions can be properly controlled to completely degrade polymers in landfill.

Michael Stephens, technical director of Symphony Environmental, a subsidiary of Symphony Plastics, steps in to answer questions over the degradable polyethylene d2W recently adopted for carrier bags by the Co-op, Somerfield and Kwik Save.

PTI: What is d2W and how does it work?

MS: d2W technology was originally found in a small chemicals company in the US – Environmental Products Inc – where it was being used as biodegradable daily landfill cover.

Our chief executive saw that there was an opportunity to use it in general packaging applications.

The way it works is that the d2W additive is activated once the polyethylene is extruded. Then we put in inhibitors so that it will degrade at different times depending on whether it is a bread bag or a bin liner.

We don't choose to call it biodegradable because d2W will degrade without the influence of living organisms. Whereas starch-based biodegradable plastics need a microbiactive environment, our material will degrade wherever it is.

PTI: There is some mystery surrounding the active agent that enables it to degrade in all circumstances, are you able to satisfy industry curiosity?

MS: The agent is the commonly known metal ion system. It's a metal salt that is extracted and converted into d2W to become the prodegradant and we balance it with inhibitors to determine the life expectancy.

This technology has been around since the 70s. It used to be used in photodegradation. What we've done is develop it and make it far more predictable and far more efficient. We have accelerated the evolution of this technology to a point where it is compatible with all sorts of plastics.

We're quite cagey about revealing how we inhibit it and which particular metal salt we're using. It's the methodology of combining the prodegradent with the inhibitors and how we introduce them to the host plastics, so it's a variety of combined activities that makes d2W work.

We have done a lot of background testing into use with different substrates with independent plastics testing facilities including Pira International, Rapra and OWS in Belgium. d2W was successfully tested for direct food contact and has passed eco-toxicity tests.

PTI: Why do you think UK industry has reservations over the development of degradable plastics?

MS: In mainland Europe there is far more interest and acceptance of degradable plastics than there is in the UK.

First of all, the starch-based plastics that have been around for about five years are very expensive. Although they are found to be justifiable in green waste collection schemes where you can see a clear route to compost.

Also the European directive in its original format recognises bio-degradability as a definition of recoverability. But the British legislation deleted degradability as a definition back in 1995 when it was put together.

Why did they do that? Two reasons – one was the vested interest from industry at the time which had invested an awful lot of cash into recycling. So there were some very big players and it really wasn't in their interest to encourage degradability. And also there wasn't really a commercially viable degradable product available. Compostability was included but degradability in its isolated form was deleted.

PTI: Industry argues that degradable plastics contradict the first principle of sustainability how do you justify d2W as a benefit to the environment?

MS: We think sustainability has a lot of virtues. In 10 years time we will be looking seriously at sustainable-renewables such as polylactic acids but those are expensive at the moment and full of flaws. There is still a lot of life-cycle assessment to be done.

Right now we are using nearly a billion tonnes of PE a year and most of that goes into landfill. So at least if it's degradable over the next 2-5 years then when sustainable-renewable solutions do come on board there won't be a backlog of 10 years of PE to put up with.

It's companies like Symphony using our current technology to make a pragmatic first step that will fund research into these other products. But you've got to start somewhere. You can't get to 2010 and suddenly find sustainable-renewables. You've got to start by changing peoples' habits looking at green waste collection and segregation going into compost.

PTI: But right now the UK is sadly lacking in composting facilities – isn't it the case that the country is not yet ready for your technology?

MS: This is part of the problem. When we started selling degradable bags for green waste collection to local authorities people said 'this bag's fantastic it goes into compost – but we've got no way of collecting it and no compost site to put it in'.

I think this will change as people become aware of the availability of this technology and as the infrastructure starts to take form. 75% of local authorities are now carrying out green waste collection schemes of some sort which go to compost – we're dealing with 50 at the moment.

PTI: In the mean time most d2W bags will end up in landfill. If the UK is meant to be reducing biodegradable waste in landfill aren't developments such as d2W making it harder for industry to reach these targets?

MS: What we're getting at is this is a solution for today. We're not saying this is the big panacea and it will solve all our packaging waste problems. What we're promoting is a very economical solution to the packaging waste problem. The Co-op is not paying any more for its d2W bags. It's an immediate contribution to this problem and it's a darn site better than using conventional plastics that will last forever whatever happens.

PTI: What evidence do you have that d2W will breakdown in landfill?

MS: Well you can simulate to some extent the conditions in landfill but these conditions vary considerably.

In landfill we're not concerned particularly with its total degradation. What we're interested in is that its mechanical integrity breaks down sooner than its final molecular degradation. The molecular breakdown can take longer. It's difficult to predict since it depends on bacterial activity.

The thing to bear in mind with our material is that it is inherently degradable and it doesn't matter if it never meets bacteria. But once it has disintegrated into tiny pieces molecular breakdown can be accelerated by microbial organisms and then it does become biodegradable.

PTI: So where next for d2W?

MS: We've found that carrier bags are a good Trojan Horse because if a retail grocer subscribes to degradable technology then it is very difficult not to move the technology into all their plastics products. We are doing trials on a number of new products including modified atmosphere packaging.

Scientifically, it is possible to produce solid plastics with d2W but we've concentrated on the flexible packaging as we feel it's more of a litter and waste problem. We're working on rigid but it's not commercially achiev-able yet.

And right now I am off to the British Standards Institute to continue our launch of a second standard for oxy-degradable plastics.

At the moment we only have a standard for starch-based biodegradable plastics and this is not suitable for products that don't rely on living organisms to degrade. If the review is passed then the new standard could be active by next August.