Why Biodegradable?

Incidentally, some confusion has been caused by use of the term “oxo-degradable.”  Nobody puts pro-degradant additives into plastic and markets it as “oxo-degradable,” and nobody would want it, if all it does is to create fragments of plastic.

“Oxo-degradation” is defined by CEN (the European Standards authority) in TR15351 as “degradation resulting from oxidative cleavage of macromolecules.”  This describes ordinary plastics, which abiotically degrade by oxidation in the open environment and quickly create fragments, but do not become biodegradable except over a very long period of time.

“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.

So, what is oxo-biodegradable plastic and why was it invented?

It was invented in the 1970s by Professor Scott and other polymer scientists who had realised by then that polyethylene and polypropylene could cause an environmental problem if it escaped from the waste management processes and ended up in the open environment as litter.

Knowing that most of it would not be collected, they discovered that if they introduced into the normal polyethylene or polypropylene a tiny amount of a catalyst (which is usually a salt of manganese or iron) the plastic would not start to degrade while it is in storage and  would perform in exactly the same way as normal plastic whilst in use, but if it was discarded into the open environment it would rapidly become biodegradable, and be consumed by bacteria in the same way as nature’s wastes.

In cricketing terms it is a long-stop, to protect the environment if all else fails.

Their idea was that manufacturers would stop using ordinary plastic, and would upgrade it with their new technology at little or no extra cost.

Sadly, this has not been adopted widely enough, so the plastic continues to lie or float around for decades.  Prof. Scott said just before he died that if his invention had been more widely adopted there would be no ocean plastic garbage patches.

The reason why ordinary plastic is not biodegradable is that it comprises long entangled chains of molecules, which give it a high molecular-weight, and this is too high for the material to be accessed by microbes. The molecular-weight of ordinary plastic does reduce naturally over time, but it takes very many years -some say 100 years – before ordinary plastic ceases to be a plastic and has become biodegradable.  So, what the d₂w catalyst does is to cause the molecular chains to be dismantled by oxidation so that the material is no longer a plastic and becomes biodegradable.  The important thing is not the size of the fragments, but the molecular-weight.

Light and heat will accelerate the process, but it will continue even in dark, cold, conditions.  Moisture is not necessary for oxidation, and does not prevent it.

Life-cycle assessments by Intertek have shown that it has a better LCA than the other materials used for packaging.

So that is what d₂w oxo-biodegradable plastic is for – but what is it NOT for?

1. It is NOT a disposal route. The intention is that the plastic is reused, recycled, and disposed of like normal plastic, but the d2w technology will make sure that if the plastic gets into the open environment the molecular weight will reduce very rapidly so that it becomes biodegradable.
2. It is NOT for landfill. If the plastic has been taken to landfill, it has been responsibly disposed of and there is no need for it to degrade. Also, if anything biodegrades in anaerobic conditions it will generate methane, which is undesirable unless the landfill has been designed to collect the gas.  Oxo-biodegradable plastic will not degrade in the absence of oxygen.
3. It is NOT for composting.    See https://www.biodeg.org/subjects-of-interest/composting/

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UK On 14^th November 2022 the Environment Minister said “our call for evidence suggests these materials are often stripped out at the start of the process and landfilled or incinerated.”

On 2nd December 2022 the Minister said: “Compostable plastics must be treated in industrial composting facilities to be broken down and, when processed incorrectly, can be a source of microplastics and contaminate recycling streams.”

“This packaging does not contribute to a circular economy in the same way as packaging that can be reused or recycled into new packaging or products do, as compostable plastic packaging is generally intended to be used only once.”

There are a number of questions which are always raised:

1. Microplastics. – Some of the microplastics found in the environment are coming from tyres and man-made fibres, but most of the microplastics are caused by the fragmentation of ordinary plastic when exposed to sunlight. These fragments are very persistent in the environment because their molecular weight is too high for microbes to consume them, and can remain so for decades.

This is why oxo-biodegradable plastic was invented. The plastic falls apart because the molecular chains have been dismantled and it is no longer a plastic.  (When Ellen MacArthur Foundation asked Professor Jakubowicz for his advice He made this point, but they ignored it).  See  https://www.biodeg.org/wp-content/uploads/2019/11/emf-report-1.pdf

The European Chemicals Agency (ECHA) were asked to study oxo-biodegradable plastic in December 2017.  They made a Call for Evidence, and they informed us after 10 months that they had not been convinced that it creates microplastics. ECHA have never provided a dossier to support any ban on oxo-biodegradable plastic, and there is no evidence that microplastics from oxo-biodegradable plastic have ever been found in the environment.

It has been used for bread bags for more than ten years by the largest bread producer in the world (Bimbo bakeries) and there have been no problems with microplastics or recycling.

1. that oxo-biodegradable plastic will contaminate a recycling stream and is incompatible with a circular economy. That is not correct, but it is correct for “compostable” plastics, which are not recyclable.   Five points on recycling:

• Recyclers have to assess the level of degradation of any plastic sent for recycling whether it is oxo-biodegradable or not. They cannot recycle ordinary plastic which has started to degrade after exposure to sunlight.
• If the recyclate is to be used to make short-life products (eg food packaging) it does not matter whether it contains oxo-biodegradable plastic, because biodegradation is actually desirable.
• Stabilisation is therefore necessary only for long-life products, and the producer of long-life products would stabilise them in the same way whether the recyclate contains oxo-biodegradable plastic or not. He does not need to know the proportion of oxo-biodegradable plastic in the feedstock. This normal stabilisation would neutralise any oxo-biodegradable residue.
• It is not necessary to separate oxo-biodegradable PE or PP from conventional PE or PP before recycling, but if so desired oxo-biodegradable masterbatch could be made visible to automatic sorting equipment by including a marker.
• Oxo-biodegradable masterbatch is used in PE and PP, but NOT in PET.

1. that recycling is preferable to biodegradation. Yes, but it is not possible to recycle plastic which has escaped into the open environment from which it cannot realistically be collected.  The ONLY way to deal with it is biodegradation.
2. has it been shown that oxo-biodegradable plastic will fully biodegrade? Yes, tests have been done by Intertek showing biodegradation of 92.74% when tested according to ASTM D6954. (The percentage required by EN13432 for “compostable” plastic is 90%).   No reason has been shown why biodegradation should stop before it is complete.  You will never find 100% carbon-evolution because some of the material converts into water and biomass. Even if it did not fully biodegrade it would still be better than ordinary plastic, which would have created persistent microplastics but would not have biodegraded at all.
3. EN13432 for “compostable” plastic requires biodegradation to be tested in a laboratory (not in a compost heap) but it is suggested that oxo-biodegradable plastic should be tested in outdoor conditions. (para. 49 of Summary) See however the statement of Dr. Graham Swift (Vice-chairman of the Technical Committee at ASTM) https://www.biodeg.org/wp-content/uploads/2021/02/Swift-evidence-to-BEIS.pdf who says “It has been my experience that results from laboratory testing are very likely to be reproduced in the real world. I can see no cause for concern that they would not, and have seen no evidence that they have not.”

Further, the Oxomar project was a four-year interdisciplinary study, sponsored by the French Government. https://www.biodeg.org/wp-content/uploads/2021/07/Final-report-OXOMAR-10032021.pdf   The scientists said that “The goal was to evaluate the biodegradation of OXO-bio in marine waters.”

In their conclusion they reported that “We have obtained congruent results from our multidisciplinary approach that clearly shows that oxo-biodegradable plastics biodegrade in seawater and do so with a significantly higher efficiency than conventional plastics. The oxidation level obtained due to the d2w prodegradant catalyst was found to be of crucial importance in the degradation process.”

See also the report from Queen Mary University London by Rose et. al 11th February 2020. https://www.biodeg.org/wp-content/uploads/2022/10/QM-published-report-11.2.20-1.pdf     Para 2.6 says “prior to testing, samples of LDPE and oxo‐LDPE were surface‐weathered in sea water for 82 days, undergoing natural variations in sunlight and UV intensity.

1. that they cannot be sure how long the plastic will take to biodegrade in the open environment, but it is not disputed by anyone that it will be many times faster than ordinary plastic when exposed under the same conditions in the open environment. Queen Mary University say up to 90 times faster https://www.biodeg.org/wp-content/uploads/2022/10/QM-published-report-11.2.20-1.pdf      para 2.3

EUROPEAN UNION

We were not entirely surprised to see in December 2022 that the homes and hotels of 18 MEPs and officials had been searched by the police, yielding suitcases stuffed with banknotes.

The reason we were not surprised is that we have never been able to understand how it was possible to impose a ban on “oxo-degradable plastic” (by Art. 5 of the Single-use plastics Directive 2019/904) without any dossier from the European Chemicals Agency (ECHA) showing any justification for any such ban.  To make matters worse, the Commission had actually asked ECHA (under Art 69 of the REACH Regulation) to study whether these products created microplastics.  ECHA received hundreds of pages of evidence but they informed us in October 2018 that they were not convinced that microplastics were formed.  They were instructed to terminate the study.

The Commission’s draft Directive did not include any ban on oxo-degradable or oxo-biodegradable plastic, but the Parliament proceeded to legislate, and circumvented all the safeguards against arbitrary legislation provided by Arts. 69-73 of REACH.   Could it be that there was some improper influence?

This Directive has been challenged in the European Court in Luxembourg and the case was heard by five judges on 20^th March 2023.  We await their decision.

The loser here is the environment, because ordinary plastic is still being used to make products which get into the open environment every day, where they will lie or float around for decades. They should urgently be made with d2w oxo-biodegradable technology, so that they will biodegrade much more quickly and will not leave harmful residues.

d₂w technology is supplied to plastics manufacturers as a masterbatch in pellet form, so that they can upgrade their products with the same machinery and workforce, at little or no extra cost.  It is a “drop-in” technology.