WHY BIODEGRADABLE

There is one thing on which we can all agree – that it is important to protect the environment, and especially the oceans, from plastic pollution.

“Reduce, redesign, re-use and recycle” have been tried for many years, but the problem is getting worse. Efforts to physically remove plastic from the ocean are also being tried but the costs are enormous. An organisation called “Ocean Cleanup” says that “The Great Pacific Garbage Patch can be cleaned for $7.5 billion.” The problem is that as fast as they remove it a larger quantity will get into the oceans, especially from Asia.  It is now clear that the only way to prevent plastic accumulating in the oceans is to make it oxo-biodegradable with a d2w masterbatch, so that it will quickly biodegrade without any human intervention.

Plastic products are immensely useful, especially for the poorest people, as they are very effective for protecting their food and water from contamination and deterioration.  There is nothing wrong with polyethylene or polypropylene except that it can persist for a long time if it gets into the environment.  It is made from a by-product of oil which used to be wasted, so until the world no longer needs petrol and oil for engines it makes sense to use this by-product. Oxo-biodegradable technology can also be used to confer biodegradability on plastics made from crops such as sugarcane.

An important piece of research has just been published from the Universities of Sheffield, Stockholm, and Cambridge, concluding that care must be taken when formulating policies so that we do not inadvertently drive a shift to non-plastic alternatives with higher GHG emissions. See: the Denkstatt Report which says it would be a mistake to ban plastic packaging – and   Replacing Plastics with alternatives is worse for Greenhouse gas emissions in most cases.  See also  – Paper Bags.

We support efforts to improve waste management and to prevent the escape of plastics into the environment, but until these efforts are wholly successful throughout the world, we think that plastic products should be made so that they will not persist for decades but will instead biodegrade and be returned to the eco-system by naturally occurring bacteria and fungi.

We would like to explain how d2w masterbatch technology can help to do this

Professor Gerald Scott, Aston University

The mechanism of abiotic peroxidation of hydrocarbons has been extensively studied over the past 50 years. D2w plastic 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.

So, knowing that much 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 quickly become biodegradable if it escaped into the open environment, and be  consumed by bacteria in the same way as nature’s wastes. During its useful life it would perform in exactly the same way as normal plastic, and can be re-used and recycled.

So 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 the ocean plastic garbage patches would be very much reduced

He described it as “an insurance policy, to protect the environment if all else fails.”

In 2021 the Environmental Protection Agency of the USA issued a Report on their research into pro-oxidant masterbatches stating that they “could significantly reduce the persistence of plastic pollution without creating undesired by-products.”

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.

It is crucially important to understand how the hydrocarbon polymers degrade in the environment by a combination of peroxidation and bioassimilation and how the free radical chain mechanism can be controlled by antioxidants. It would be possible to make oxo-biodegradable plastic so that it started to degrade immediately, but it would then have no useful life, and sustainability must in practice be a compromise between commercial viability (i.e., cost-performance) and environmental acceptability. Bioassimilation of plastics residues in the environment is an essential but not the only requirement of technologically useful packaging plastic, and in most cases, plastics require a controlled lifetime before physical degradation commences.

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

Oxo-biodegradable plastic is now mandatory in Saudi Arabia, the UAE, Bahrain, Jordan and most recently Yemen, where the Government will not allow imports of a wide range of plastic products and packaging materials unless they are made with d2w.  They will not renew the licences of factories who are found to be making the products in Yemen without d2w.  They have issued warning notices to factories, and Government inspectors and customs officers have been equipped with a hand-held device which can detect the presence of d2w in the plastic.

Yemen has a population of 28.5 million and produces more than a million tonnes of plastic products per annum.

The lobbyists for the “compostable” plastic industry will say that Yemen is a less-developed country and the government are allowing themselves to be duped into mandating a technology which doesn’t work. In fact, they are following the lead given in their region by Saudi Arabia, Bahrain, and the UAE.  They all instructed experts to study the technology in detail and satisfied themselves that it will degrade and biodegrade in the environment much more quickly than ordinary plastic, leaving no microplastics or toxic residues behind.

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

  1. It is NOT a disposal route. The plastic is designed to be reused, recycled, and disposed of like normal plastic, but the d2w technology will make sure that if it gets into the open environment the molecular weight will rapidly reduce so that it becomes biodegradable.
  2. It is NOT primarily intended for Landfill, because if the plastic has been taken to landfill, it has been responsibly disposed of and there is no need for it to degrade. However, there will usually be enough oxygen in a landfill to cause degradation, and subsequent biodegradation.
  3. It is NOT sold for Composting, although it will biodegrade in a composing facility. Five short points on plastic marketed as “compostable”:
  • It does not deal with the problem of plastic litter in the environment, because it is designed and tested to biodegrade in a composting facility, not in the open environment.
  • It does not convert into compost (EN13432 and ASTMD6400 require it to convert into C02 gas) It is therefore designed for a deliberate linear process and is not circular. The material is intended to be wasted and lost to atmosphere by conversion into CO2.
  • It cannot be re-used, recycled, or made from recyclate
  • It can leave microplastics in the compost and in the open environment
  • It is not wanted by industrial composters and local authorities.

It should not therefore be described as compostable or biodegradable and it should not be made mandatory.  On 14th November 2022 the UK 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.”

ARGUMENTS AGAINST OXO-BIODEGRADABLE PLASTIC

There are a number of issues which are always raised:

  1. Microplastics. – See the BPA Note on this subject.

Some of the microplastics found in the environment are coming from tyres and man-made fibres, and recycling is also a source of microplastics, but most of the microplastics found in the environment are caused by the fragmentation of ordinary plastic when exposed to sunlight. These fragments are very persistent 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, to deal with microplastics by making the plastic biodegradable. The plastic then 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 in their publications).

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

d2w 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. Recycling: 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:
  • If the recyclate is to be used to make short-life products (eg food packaging) it does not matter whether it contains d2w, because biodegradation is actually desirable in case the item becomes litter.
  • Stability 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 d2w or not. He does not need to know the proportion of d2w plastic in the feedstock, because normal stabilisation would neutralise any oxo-biodegradable residue.
  • It is not therefore 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.
  • Recyclers have to assess the level of degradation of any plastic sent for recycling whether it is oxo-biodegradable or not. They cannot recycle plastic which has started to degrade after exposure to sunlight, whether it contains d2w or not.
  • 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 prevent it accumulating there for decades is to make it with a d2w masterbatch.
  2. has it been shown that oxo-biodegradable plastic will fully biodegrade? Yes, tests have been done by Intertek and other accredited test-houses showing biodegradation of 90% or more and no reason has been shown why biodegradation should stop before it is complete. (Tests 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 only in outdoor conditions. See however the evidence of Dr. Graham Swift (Vice-chairman of the Technical Committee at ASTM) 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.” (See also: Professor Gerald Scott and Dr. David Wiles paper)
  • Further, a four-year interdisciplinary study, known as the Oxomar project, has been sponsored by the French Government. The goal was to evaluate the biodegradation of OXO-bio in marine waters.
  • In their conclusion the scientists 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.” Having established biodegradability the scientists did not find it necessary to continue the test until the material had completely biodegraded.
  • See also the report from Queen Mary University London by Rose et. al 11th February 2020. 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.”
  • See also the certificate issued according to AFNOR AC T51-808 by the Centre National d’Evaluation de Photo protection Université Blaise Pascal Clermont Ferrand.
  • In March 2024 researchers at Tokyo University confirmed the biodegradation of biodegradable plastics in harsh deep-sea environments. According to the leader of the team “To mitigate future marine plastic pollution, we must use biodegradable plastics in products where leakage into the marine environment is unavoidable.”
  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 (at para. 2.3) up to 90 times faster. There is no need for it to biodegrade within the 180 days required for plastic designed to biodegrade in composting.
  2. That oxo-biodegradable plastic encourages littering. However, much of the litter escapes by accident and is blown by the wind. Insofar as it is deliberate, would the kind of person who throws a plastic bag out of a car or train window bother to look for a label to see that  it is biodegradable? There is in fact no need to label the product as biodegradable at all, because it is designed to be used and disposed of in the same way as ordinary plastic. Littering is in any event more likely with paper and cardboard which are known to be biodegradable, and plastics labelled as “compostable.”

PAPER

It might be thought that paper is more environmentally-friendly than plastic – after all it is made from trees. But it doesn’t grow on trees, so the trees have to be destroyed to make the paper.  In fact it takes 24 trees on average to make just one ton of paper.

It also takes more than four times as much energy to manufacture a paper bag than a plastic bag.  Whole forests are cut down to make paper – forests that could be helping the environment by absorbing greenhouse gases.

For details, see BPA briefing note on plastic v paper

AGRICULTURAL MULCH FILM

Farmers all over the world spread thousands of square kilometres of plastic sheet on their fields to protect their crop from weeds and to reduce the evaporation of water.  Essentially, farmers have three options:

1 –  CONVENTIONAL PLASTIC – after the harvest the farmer has to drag many hectares of plastic off his fields. He is not allowed to burn it on the farm, and burying it is not a good idea because it is labour-intensive and effectively puts the site out of cultivation, so he has to pay for it to be taken away. Some farmers send their plastic for recycling but it is usually contaminated with mud and other contaminants, so recycling does not make a lot of sense in economic or environmental terms when you consider the cost of hauling the plastic off the field, loading a large truck, and driving it along country roads to a recycling facility often hundreds of miles away – using fossil fuels, causing congestion, and emitting pollution. The plastic then has to be washed and the contamination has to be disposed of – and then the plastic has to be processed into recyclate.

Also, having lain on the fields exposed to sunlight it is likely to have degraded to the point that it is not fit for recycling, and fragments will be scattered by the wind whilst being removed.
2 –  PLA – this is expensive and may not be strong enough to resist tearing. The timescale for degradation cannot be programmed. A report of field-trials in Korea in 2024 says “It’s difficult to use agricultural mulching film made with PLA extracted from corn as it is difficult to set up the film on the field and there is hydrolysis due to rainwater, so the physical properties of the mulching film drop. As a result the function of the mulching film wasn’t maintained after 40 days, and it was impossible to use the film. But for the mulching film made with d2w, the physical properties of the film were maintained for 6 months even in the area where there is a lot of rain.
3 –  D2W PLASTIC – successful field-trials have been run in Wales. Which showed that the next time the field is ploughed, the biodegradable residue will be returned to the soil, where it will be bioassimilated by the bacteria and will provide a source of carbon for next year’s plants.

By taking note of the type of crop and climatic conditions in the area, and using the correct formulation, it is possible to make the plastic last for as long or short a time the farmer requires.  It is no more difficult to spread d2w plastic on the fields than ordinary plastic, and a company in Ireland called SAMCO are selling it to farmers and have invented a machine for laying the film.

Mulch films made with d2w-type biodegradable polymers have been studied by scientists for more than 20 years.  At page 47 of “Degradable Polymers, Principles and Applications” (ISBN  1-4020-0790-6)  Professor Scott says “The degradation products formed by oxo-biodegradation are of benefit to the agricultural environment as biomass and ultimately in the form of humus.

Carbon is retained in the soil during oxo-biodegradation in a form accessible to growing plants, rather than by being emitted to the environment as carbon dioxide, as is the case with hydro-biodegradable polymers (e.g. pure cellulose and starch) ….. Time control of biodegradation of the synthetic carbon-chain polymers is achieved by antioxidants that behave similarly to naturally occurring antioxidants present in lignin and tannin.”

See also “Polymers and the Environment” by Prof. Scott.

With regard to the edges of the mulch film which are buried to hold it in place.   They will still biodegrade because, unlike photo-degradable plastic, an oxo-biodegradable plastic does not need constant exposure to sunlight.  It is also possible to make a mulch film in which the buried sides of the film incorporate a different biodegradable masterbatch as compared to the middle part of the film

EUROPEAN UNION

Symphony Environmental Technologies Plc have sued the EU in their own court

In their evidence to the European Chemicals Agency in 2018 INTERTEK said: “Almost all the micro-plastics found in the oceans have come from the fragmentation of conventional plastics. Although conventional plastics can fragment quite quickly on exposure to sunlight and mechanical stress, the fragments remain for years at a molecular mass which is too high for biodegradation. This means that conventional plastics can persist in the ocean for decades before they become biodegradable. This is why the micro-plastics tonnage in the oceans has built up: the inflow and dwell time exceeds the outflow (outflow being disappearance due to biodegradation). If the dwell time were shorter, and/or the inflow lower, build up would not occur and the micro-plastics problem would not exist.”

“The faster degradation and subsequent biodegradation of oxo-biodegradable plastics means that they enter the eco-system as waste plastic in the same way as conventional plastic, but they degrade, and then ultimately biodegrade to natural materials and are recycled back into nature in less time than conventional plastics. This means that oxo-biodegradable plastics have a shorter dwell-time in the ecosystem. In the case of micro-plastics in oceans, a shorter dwell time means a net reduction in the overall amount of micro-plastics in the oceans.”

“The oceanic micro-plastic problem has arisen because the dwell time of conventional plastics is too long compared to the rate of arrival of more plastics. If the dwell time were shorter (i.e. conventional plastics degraded faster) and/or the incoming flow was less, the ocean would be able to handle a certain amount of plastics. The plastic contamination would disappear from the system (through biodegradation) faster than it would arise in the system (through waste plastic reaching the ocean) and there would be no build up. It is simple, undeniable physics, little different from the physics of flow of liquids through pipes.  Oxo­ biodegradable plastics, through biodegrading faster, and thus having a shorter dwell time in the system, have the potential to aid the problem rather than worsen it.”

“Any improvement in the speed of degradation must be useful. Considering very approximate order of magnitude figures, if conventional plastics were considered to take say 20 to 200 years to biodegrade in the oceans, and oxo-biodegradable plastics take say 1 to 10 years to biodegrade, already the oxo-biodegradable plastics are showing potential to make a positive, rather than negative, contribution to the issue.”

“Various stakeholders have offered opinions on oxo-biodegradable plastics, including raising doubts about their efficacy and even doubting the point of them. Oxo-biodegradable plastics have been criticised for:

(a)       Increasing the amount of plastics, which is obviously illogical. The presence or not of an oxo-biodegradable additive in a plastic does not change the amount of plastic.

(b)       Encouraging a throw-away society, which of course they do not. The littering and inappropriate waste management that leads to the oceanic micro-plastic problem occurs irrespective of any additives in the plastics. Much of the littering is accidental, and the kind of people who deliberately throw litter do not care whether the plastic may be a type of biodegradable plastic.

(c)       Being less desirable for re-use and recycling. Oxo-biodegradable plastics are not antagonistic to re-use and recycling. As has been demonstrated by the technical reports, and in practice over years of recycling, the tiny amounts of oxo-biodegradable additive in the system make no difference to recycling or re-use.

(d)       Not being supportive of the circular economy. There is a clear theoretical benefit to a circular economy. However, that is a different issue from the current harsh reality of micro­ plastic pollution. If society wished to eliminate anything that is not  supportive of the circular economy, it should first stop burning oil, which is a non-circular threat to sustainability that is orders of magnitude greater than the amount of oil going into making useful products such as plastics. The material used to make plastics is in any event an inevitable by-product of the process of making fuels, and the same amount of oil would be extracted from the ground if plastics did not exist.”

“Some of the opinions voiced by some parties have led some stakeholders to consider a potential ban on oxo-biodegradable additives. This seems unjustified, unnecessary, and counterproductive. For the foreseeable future, conventional plastics will continue to be used all over the world, in increasing amounts due to global development, despite the efforts of environmentalists and governments in some countries. Even if oxo-biodegradable technology was no longer available on the European market, large quantities of conventional plastics will continue to enter the ecosystem and will remain there as a problem for future generations. Therefore, a ban would be ineffective because it would have no perceivable impact on the problem.”

“A ban of any product would normally be justified only where there existed proof of significant harm. In the case of oxo-biodegradable plastics, the worst possible case (based on the views of the most sceptical stakeholders) could be that oxo-biodegradable plastics are little different from conventional plastics in terms of environmental impact. The best possible case is that they would be beneficial in relation to the micro-plastics issue. The point is that the range is neutral-to-good, not harmful. Therefore, a ban does not seem to be logical or justified.”

“Perhaps the most important point is this: whatever the speed of degradation, it is faster than that of conventional plastics. The different opinions of various stakeholders concerning the speed of degradation, and the different findings of the research that has been carried out to date, are simply a matter of degree