CONFUSION ABOUT OXO
Confusion is being caused by the failure of the EU Commission, the Ellen MacArthur Foundation, and others who ought to know better, to use the correct definitions:
“Oxo-degradation” is defined by CEN (the European Standards authority) in TR15351 as “degradation identified as resulting from oxidative cleavage of macromolecules.” This describes ordinary plastics, which abiotically degrade by oxidation in the open environment and create microplastics, but do not become biodegradable except over a very long period of time.
By contrast, “oxo-biodegradation is defined by CEN as “degradation resulting from oxidative and cell-mediated phenomena, either simultaneously or successively”. This means that the plastic degrades by oxidation until its molecular weight is low enough to be accessible to bacteria and fungi, who then recycle it back into nature. These plastics are tested according to ASTM D6954.
LEGO – SWAPPING PLASTIC FOR PAPER
Their new bags are heat-sealed, meaning that they are coated or laminated with a polymer which will either be polyethylene (believe it or not!) or some hugely cross-linked starch-based plastic product that will not break down easily.
I don’t see the benefit here, but being located in Billund they align themselves closely with the Scandinavian paper producers. See Paper Bags
They are probably also responding to perceived customer pressure generated by alarmist stories about plastic from the NGOs. I used to respect the NGOs but find it difficult to do so now.
I often receive scientific papers purporting to show that oxo-biodegradable plastics do not work as claimed. I ask an experienced polymer scientist to analyse them, and they all turn out to be unscientific, or irrelevant, or both.
I have just dealt with some papers sent by DEFRA. One of them used a test material so heavily loaded with stabilisers that it was hardly surprising that it had not degraded.
Another did not identify the composition of the test material, so it was impossible to know whether it had been correctly made – or that it was oxo-biodegradable at all.
Another said “the ubiquitous and repeated application of mulch films resulted in increasing quantities of plastic film residuals in the agricultural and horticultural fields, as mulch films deteriorate and fragment during the growing season and are very difficult to be fully recollected from the soil. Up to 25%–33% of total mulching input could remain in the field each year.” All this has been well known for many years, and is the reason why farmers and growers should not be allowed to use plastic mulch film which is not oxo-biodegradable.
Another exposed the plastic to uv ageing for a time much shorter than the industry standard requires, and then wondered why not very much biodegradable material had been produced.
Another made the obvious point that oxygen attacks the plastic at the surface and then penetrates further into the material. This paper confirmed that “initial abiotic oxidation helps to reduce the molecular weight of oxo-biodegradable polyethylene and form easily biodegradable product fractions”
It is interesting to read these papers, and some of the flaws are evident even to me as a layman, but the confusion they cause is really bad for the environment. While confusion continues, too many people are not using oxo-biodegradable technology, so their plastic which escapes into the environment will create microplastics and lie or float around for decades. It’s time governments realised that they can’t solve this problem with the 3 R’s.
Michael Stephen is a lawyer and was a member of the United Kingdom Parliament, where he served on the Environment Select Committee. When he left Parliament Symphony Environmental Technologies Plc. attracted his attention because of his interest in the environment. He is now Deputy Chairman of Symphony, which is listed on the AIM market of the London Stock Exchange, and is the founder and Chairman of the Biodegradable Plastics Association.
Earlier Postings in this Column
Interview with Michael Stephen
The opinions expressed here by Michael Stephen and other columnists are their own, not those of Bioplasticsnews.com