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Bogus or bonafide? Finally, a definitive investigation of the claims of oxo-degradability

Organic Waste Systems (OWS), based in Gent, Belgium, and IKT-University Stuttgart have announced they are embarking on a multi-client project, which, they say, is designed to settle once and for all, the longstanding acrimonious controversy about oxo-degradable plastics. Are they biodegradable? Or are they not?

Karen Laird

September 16, 2014

3 Min Read
Bogus or bonafide?  Finally, a definitive investigation of the claims of oxo-degradability

Last year, OWS performed a large desk research study for PlasticsEurope, which investigated, among other things, the abiotic and biotic degradation of oxo-degradable plastics, to verify whether these match with the many claims which are today being made in the market. The study found that at least three fundamental claims made on behalf of oxo-degradable plastics were questionable. "Independent proof (or disproof) of these claims is today not (yet) available," wrote OWS.  "Therefore, a logical next step would be to verify these claims by means of laboratory testing." Hence the proposed project.

But first, a little background information, to ensure that everyone is up to speed on the issue at stake.

Biodegradable plastics, which readers may or may not realize, can be derived from biomass or from oil. They offer an ideal solution in certain applications, such as those in which where biodegradability plays a functional role, and as such, has an added value. A number of applications leap to mind: the compostable, biodegradable mulch film used in the agricultural industry, which does not have to be collected after use on farm fields for example, or biowaste bags for organic household waste.

What biodegradable plastics were not ever intended to be was a solution for littering.

Enter oxo-degradable plastics, the subject of the multi-client study envisaged by OWS and IKT-University Stuttgart, and which were developed for precisely that. These are conventional plastics, i.e., oil-based, that 'can be made to biodegrade in the same way as a leaf', as a major producer of these materials, Symphony Environmental, claims, thus 'reducing the blight of plastic waste.' Everyday plastics such as PE, PP, or PET are simply mixed with a small percentage of an additive, which subsequently accelerates free radical "degradation" of plastics.

It sounds great - in fact, it seems like the perfect answer to plastic litter. And these oxo-degradable materials are indeed finding a market in numerous countries around the globe, for exactly that reason.

The hitch, however, is that scientifically based evidence is lacking from independent laboratories or certification bodies that full biodegradation actually occurs. In fact, many experts believe that something quite different happens, namely that these plastics fragment into tiny pieces that, instead of biodegrading, are dispersed into the environment.

As one such expert, Dr. Jim Lunt, wrote in 2008 in a blistering letter to the editor of a publication (Exchange Morning Post) that had mixed up biodegradation and oxo-degradation: "It is true that polyolefins such a PP and PE will fragment in the presence of oxygen and sunlight when the stabilizers added to the material to prevent such degradation have lost their efficacy. It is also true that some additives such as heavy metals and other materials will accelerate this fragmentation. However, such fragmentation has repeatedly been shown to be purely due to breakage of the polymer chains. There has been no reputable evidence that microorganisms are involved in any of this degradation either in a aerobic compost or a anaerobic managed landfill environment. There is also no reputable evidence that these polymer fragments are attacked by microorganisms."

The controversy has led the European Commission to consider a possible ban on oxo-degradable carrier bags. And in France, a group of MPs in the French National Assembly have called for a similar ban. Predictably, the oxo-degradable plastics industry has reacted furiously.

The multi-client project aims to put the issue to rest by investigating the claims and by attempting to verify these in the laboratory. "To make this study as objective and neutral as possible, we are aiming at a broad participation including government agencies, consumer goods producers, NGO's, oxo-degradable producers and the bioplastics industry," said OWS.

Throughout the project, interim results will be provided on a regular basis. These intermediate results will be sent to all project partners, enabling them to keep track of the progress made. At the end of each phase, a report will be published and distributed amongst the project partners; a final report will appear at the end of the study.

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