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Click on the image below to watch a short video, explaining where microplastics are coming from and what can be done to reduce them.
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POSITION-PAPER ON MICROPLASTICS
Highlights
- Oxo-biodegradable plastics are recyclable and do not create microplastics.
- Oxo-biodegradable plastics will properly biodegrade if they meet International Standard ASTM 6954
- Oxo-degradable and Oxo-biodegradable are not the same, and are defined by CEN
The Global Issue
Plastic pollution and in particular microplastics are seen today as the main problem with plastics. Microplastics are tiny pieces of plastic which are being found on land, in the sea, and now even in the air we breathe and the water we drink.
Some of the microplastics are coming from man-made fibres, and recycling can be a source of microplastics. Composting can also be a source of microplastics, but most of the microplastics found in the environment are caused by the fragmentation of ordinary plastic which becomes embrittled when exposed to sunlight and stress. It is also said that microplastics are coming from vehicle tyres, but these are fragments of rubber, not plastic.
Waste-management and education must of course be improved, but for the foreseeable future some way must be found to deal with plastic which has escaped into the environment and cannot be collected for inclusion in a circular economy.
Waste management in Switzerland is among the most efficient in the world, but the Swiss Federal Office for the Environment says:
“Plastics have no place in the environment. Nevertheless, around 14,000 tonnes of plastics end up in Switzerland’s soil and waters every year – primarily due to the abrasion and decomposition of plastic products and improper disposal of plastic waste. Plastics then accumulate in the environment because they only degrade very slowly.”
This is the reason why oxo-biodegradable plastic was invented. It is used in a wide variety of bottles, packaging, and other products made from polyethylene (PE) or polypropylene (PP), which are among those most likely to be littered. It is also very useful in agriculture. Oxo-biodegradable plastic should not be confused with the type of plastic marketed as “compostable,” which is tested to biodegrade in an industrial composting facility.
Ordinary plastic and oxo-biodegradable plastic lose their strength and fall apart at about the same time when exposed to sunlight, depending on their age and degree of stabilisation, but the fragments of ordinary plastic have a molecular weight which is much too high for biodegradation. Oxo-biodegradable technology tackles the problem at the molecular level by ensuring that the plastic does not just break up into smaller pieces. It dismantles the molecular chains within the polymer so that it ceases to be a plastic and becomes a biodegradable material which is consumed by bacteria and fungi and cleaned out of the eco-system by them.
Definitions & Explanations
It is important not to confuse oxo-degradation and oxo-biodegradation. “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 plastic, (which does not contain an intentionally-added prodegradant catalyst). It will abiotically degrade by oxidation in the open environment and create microplastics, but does not become biodegradable except over a very long period of time, because its molecular-weight is too high. It is well known that fragmentation is accelerated by colorants and other additives, but they do not cause biodegradation. Nobody puts a prodegradant additive into a polymer and markets it as “oxo-degradable.”
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 (which does contain a prodegradant catalyst) degrades rapidly by oxidation until its molecular weight is low enough to be accessible to bacteria and fungi, who then recycle it back into nature.
It is not possible to say exactly how long the plastic will take to biodegrade in the open environment, because timescale depends on how much heat and sunlight it receives and on the formulation used and other components of the plastic such as antioxidants. It is however clear that it will be many times faster than exactly the same type of plastic without a prodegradant masterbatch when exposed under the same conditions in the open environment. Queen Mary University say (at para. 2.3) up to 90 times faster. There is no need for it to biodegrade within the 180 days required by the industrial composters for plastic intended to biodegrade in composting.
Oxo-biodegradable plastic is not designed to end up in nature, but it is the only way to prevent plastic in the open environment from accumulating there for decades. It is designed to be used and disposed of in the same way as ordinary plastic, and there is no need to label the product as biodegradable. It is designed to biodegrade only if at the end of its useful life it escapes into the open environment deliberately or by accident. It can however be recycled if collected during its useful life.
Oxo-biodegradable plastics consist of conventional PE or PP with a masterbatch added usually @1%, which itself contains a salt of manganese or iron, anti-oxidant stabilisers, and a polymer carrier. It does not contain starch, because although the starch would biodegrade, the polymer would simply fall into microplastics, and it was this which gave early formulations a bad reputation. Today’s masterbatches, such as Symphony’s d2w, cause the molecular chains within the polymer to be dismantled by oxidation so that the material is no longer a plastic and becomes biodegradable.
Exposure to weathering in the environment causes the degradation of ordinary PE and PP products [1] leading to embrittlement and fragmentation in as little as 4-8 weeks[2] particularly when exposed to sunlight. They will float on the ocean because their specific gravity is less than 1. Fragmentation will also be accelerated by colorants and other impurities in the plastic.
Although ordinary plastic and oxo-biodegradable plastic lose their strength and fall apart when exposed in the open environment, the fragments of ordinary plastic have a molecular weight which is much too high for biodegradation. In the case of oxo-biodegradable plastics, Professor Ignacy Jakubowicz, one of the world’s leading polymer scientists has explained: “The degradation process is not only a fragmentation, but is an entire change of the material from a high molecular weight polymer, to monomeric and oligomeric fragments, and from hydrocarbon molecules to oxygen-containing molecules which can be bioassimilated.”
The prodegradant catalyst in the d2w masterbatch not only accelerates oxidative degradation, but also – critically – removes the dependence of this process on sunlight so that, unlike conventional plastics or photo-degradable plastics, degradation will continue in darkness – even if buried[3] – until biodegradability is achieved. Moisture is not necessary for oxidation and does not prevent it.
In summary it is clear that if plastic products are made with an oxo-biodegradable masterbatch and get into the open environment intentionally or by accident, the molecular-weight of the plastic will reduce much more quickly and it will become a waxy substance which is no longer a plastic. It will then have become a source of nutrition for naturally occurring micro-organisms.”
The European Chemicals Agency (ECHA) were asked to study this type of plastic in December 2017. They made a Call for Evidence, and they advised the BPA on 30th October 2018 that they were not convinced that it creates microplastics.” We agree with them, and have seen no evidence that microplastics from this type of plastic have ever been found in the environment. There is no report from ECHA because the Commission terminated the study when it became apparent that ECHA was not going to agree with them about microplastics.
Independent Verification
An article published in March 2024 by the American National Standards Institute (ANSI) states: “Using oxo-biodegradable technology can prevent future contributions to the accumulation of plastic waste that has escaped into the environment. Oxo-biodegradable plastic serves as a solution to littered plastic because it is recyclable and will degrade without releasing methane.”
ANSI continues “It is important to note that oxo-biodegradable plastic is not the same as oxo-degradable plastic. Oxo-degradable plastic (i.e. conventional plastic) does not biodegrade but breaks into microplastics which are then released into the environment and cause significant harm, especially to ocean life. They quickly fragment into smaller and smaller pieces (i.e., microplastics) that do not break down at the molecular or polymer level like biodegradable and compostable plastics. The resulting microplastics are left in the environment indefinitely until they fully break down over a very long period of time.”
“By contrast, oxo-biodegradation means degradation resulting from oxidative and cell-mediated phenomena, either simultaneously or successively [CEN/TR15351]. 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 for degradation, biodegradation, and ecotoxicity according to ASTM D6954-24.”
The problem is that although ordinary plastics are fragmenting, they persist in the environment, getting smaller and smaller until they are small enough to get into our bodies. This persistent particulate litter takes decades to degrade sufficiently to permit biodegradation. Also, fragmented conventional polymers are more likely to be occluded from sunlight by burial in topsoil or to be susceptible to biofouling over time, resulting in a reduced rate of degradation.
Oxo-biodegradable plastic was invented fifty years ago, not by marketeers or salesmen, but by the scientists who had themselves created plastics and who realised that the durability which they had achieved could actually be a problem. If their invention had been widely adopted there would be no ocean garbage patches today, but instead the plastics industry chose to continue to make conventional plastic products, which started to accumulate in the oceans and create microplastics which have now become a serious problem. Nevertheless it is not too late – If the invention is widely adopted today the accumulation of plastic in the oceans will start to reduce and will eventually be reversed.
Foremost among these scientists was Professor Gerald Scott, Professor of Chemistry at Aston University. He was the holder of several patents for the technology, and was later the Chief Scientific Adviser to the Biodegradable Plastics Association (BPA). He published the results of his work in many scientific publications including “Polymers & the Environment” (ISBN 9780854045785); “Degradable Polymers; Principles & Applications” (ISBN 1-4020-0790-6); and “Programmed-Life Plastics from Polyolefins: A New Look at Sustainability”
Professor Scott and the other polymer scientists made it clear in their published work that polyethylene and polypropylene containing the masterbatch which they had formulated will degrade and then biodegrade in the open environment very much more quickly than ordinary PE or PP, leaving no persistent fragments and no toxicity. Polymer scientists were also the authors of the standards for biodegradable plastics (ASTM D6954 and BS 8472) and it is not correct to say that there are no relevant standards. As to the Standards, see the evidence of one of the authors of ASTM D6954 to the UK Government. He explains why it contains a caveat recognising that laboratory environments are isolated, unlike the dynamic natural environment – in which degradation and therefore biodegradation is likely to proceed more quickly.
EN13432 does not require testing of compostable plastic in a compost heap and ASTM D6954 does not require oxo-biodegradable plastic to be tested in a field or in the ocean. In both cases they are tested according to standards designed by scientists to replicate the conditions in the environment where they are intended to biodegrade. The standards also require eco-toxicity testing to ensure that they will be safe in the environment.
In 2018 the scientific evidence was reviewed by a distinguished former deputy judge of the High Court in England. This has been confirmed by later research published by Queen Mary University London in February 2020. See also the evidence given by scientists in response to the Call-for-evidence by the European Chemicals Agency; and the evidence given by Intertek
The most recent evidence is the OXOMAR report. On 4th September 2020 scientists at the Laboratoire d’Océanographie Microbienne (LOMIC) reported on a four-year study (the OXOMAR project) sponsored by the French government, of biodegradable plastics in the marine environment. Their final report, citing six earlier published reports, was published in March 2021
The purpose of OXOMAR was to investigate whether biodegradable plastics will fully biodegrade in a reasonable time in the marine environment, and to investigate whether biodegradable plastic or its by-products create any toxicity in the marine environment. It involved the complementary expertise of four independent laboratories (CNEP, LOMIC, ICCF, and IFREMER).
They reported (at C6) “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.”
Policies & Legislation
No government in the western world has a policy for dealing with plastic waste which has escaped into the open environment, and cannot therefore fit into a circular economy. Their blind spot is that despite their best efforts a significant amount of plastic will continue to get into the open environment for the foreseeable future, which cannot be collected for recycling or anything else
D2w biodegradable technology is specifically designed to deal with this problem, and it is now compulsory in the UAE, Saudi Arabia, Jordan, Yemen, and Bahrain. It will degrade in landfill and will then biodegrade, but if it has been sent to landfill it has been responsibly disposed of. The composting Standards (ASTM D6400 and EN13432) are not relevant to biodegradation in the open environment.
The plastics industry could have addressed this environmental problem, to the great benefit of themselves and the environment, by making everyday plastic products with biodegradable technology so that they would become biodegradable much more quickly and would be recycled back into nature by bacteria and fungi. However, instead of engaging with the experts in the biodegradable plastics industry and seeking to understand it better and to explain it to their customers and to the public they have continued to make conventional plastic and have represented to the public that recycling will solve the problem. They are now being prosecuted for this by the Attorney-General of California.
It must however be obvious that recycling cannot deal with the plastic which escapes into the open environment from which it cannot be collected. Nor can the type of plastic marketed as compostable deal with the problem, for it has to be collected and taken for composting. In fact, it is difficult to see that there is any useful role for plastics in composting
What is a microplastic?
The key feature is that a fragment is not a microplastic if it is biodegradable.
The Annex XV restriction report by the European Chemicals Agency says at page 7 “The term ‘microplastic’ is not consistency defined, but is typically considered to refer to small, usually microscopic, solid particles made of a synthetic polymer. They are associated with long-term persistence in the environment, if released, as they are very resistant to (bio)degradation.
At page 13 “Microplastics are extremely persistent in the environment, are difficult to remove
once they are there.
This view is supported by the report by the Netherlands National Institute for Public Health and the Environment “Towards a definition of microplastics – Considerations for the specification of physico-chemical properties” which says (p11) The presence of plastics in the environment is of great concern because plastics are persistent
“From the perspective of the marine environment, microplastics that disappear quickly by natural processes (e.g. .. biodegradation to harmless degradation products), or microplastics that never reach the aquatic environment are not of concern.”
7.1 “the fact that a material is a microplastic does not necessarily mean that emission-reducing measures improve environmental quality. The environment only benefits from measures that actually reduce the exposure of living organisms to microplastics.”
The addition of Symphony’s d2w masterbatch is a measure that actually reduces the exposure of living organisms to microplastics – by making them biodegradable and significantly reducing their dwell-time in the environment.
This Position-paper has been reviewed by Jordi Labs in the United States, who say: “We reviewed the document and consider it scientifically sound. The supporting data is strong enough for the conclusion.”
Jordi Labs specializes in polymer analysis and have more than 40 years’ experience performing regulatory, quality control and failure testing. They are one of the few labs in the United States specialized in this type of testing. The review was performed by Dr. Yuanlin Deng, a Senior Chemist II working in Jordi Labs, who has more than six years expertise in polymer analysis.
In September 2024 scientists at Lambton Manufacturing Innovation Centre in Ontario, Canada were asked for their views on biodegradable plastic. They have concluded that oxo-degradable plastics (ie ordinary plastics) create microplastics, but oxo-biodegradable plastics do not.
Further References:
[1] Gewert, B., Plassmann, M. M., & MacLeod, M. (2015). Pathways for degradation of plastic polymers floating in the marine environment. Environmental Sciences: Processes and Impacts, 17(9), 1513–1521. See also “Ecotoxicology and Environmental Safety” Volume 271, February 2024, Accelerated fragmentation of two thermoplastics (polylactic acid and polypropylene) into microplastics after UV radiation and seawater immersion – ScienceDirect
showing that 76-day UV radiation induced the fragmentation of plastic items and microplastics formation, from both PP and PLA items.
[2] Karlsson, T. (2018). Influence of thermo-oxidative degradation on the in-situ fate of polyethylene in temperate coastal waters. Marine Pollution Bulletin, 135, pp.187-194.
[3] Vogt, N. B., & Kleppe, E. A. (2009). Biodegradable polyolefins show continued and increased thermal oxidative degradation after exposure to light. Polymer Degradation and Stability.
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