CONFUSION ABOUT OXO
There seems to be a fundamental misunderstanding about the purpose of oxo-biodegradable plastic.
There is no material which will degrade and disappear like magic if discarded as litter, so until the day (if ever) when governments succeed in preventing litter, the best that can be done is to make plastic litter degrade and then biodegrade much more quickly than it currently does. Oxo-biodegradability will not therefore PREVENT litter, but it will make the plastic much less persistent in the open environment, and this is a huge environmental benefit. It is easy to adjust the formulation so that it degrades more quickly or more slowly than specimens which have been tested.
A short period of biodegradation is prescribed in Standards like EN13432 and ASTMD6400 because industrial composters have a short timescale to which they have to work if their business is to be profitable. Oxo-biodegradable plastic is not intended for composting – it is intended to deal with litter, and I do not think that there is a role for plastic of any kind in composting See Composting
The Oxomar study Oxomar Report was a very thorough study (not just a literature review), conducted over a period of four years by a team of distinguished scientists, and sponsored by the Agence National de Recherce of France, to whom the team reported. Their conclusion was 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.”
Oxidation of plastic is an irreversible chemical process, causing the reduction of molecular-weight and resulting in biodegradable compounds as demonstrated in the peer-reviewed papers. However, as Dr. Graham Swift says in his evidence to BEIS/DEFRA Swift Evidence to BEIS “It is possible for a piece of oxo-biodegradable plastic to find itself in anaerobic conditions outside a landfill but this would be very unusual and does not invalidate the general proposition. It is for example possible for plastic to be deprived of oxygen by being heavily bio-fouled in the ocean or buried in sediment, but this is unlikely to happen quickly enough to prevent sufficient exposure to oxygen for abiotic degradation. If it did, then that small proportion of the global burden of plastic litter would perform in the same way as ordinary plastic – no better and no worse.”
With regard to microplastics, if the European Chemicals Agency, after a call for evidence, were not convinced that microplastics are formed, why does anyone think so? It is beyond doubt that most of the microplastics come from ordinary plastics, which are very persistent in the open environment because they are not made with oxo-biodegradable technology. This technology was invented to deal with microplastics by making them biodegradable, not to create them.
Propensity to litter. This is pure speculation -the idea that the type of person who throws a plastic bag out of a car window would satisfy himself first that it was biodegradable is frankly ridiculous, but if it were true, why are governments not banning the type of plastic marketed as “biodegradable and compostable?” There is in any event no reason why an oxo-biodegradable product should be labelled as biodegradable at all, and consumers should always be advised to dispose of products responsibly.
Less easy to collect? What proportion of plastic which escapes into the open environment is ever collected? Oxo-biodegradable plastic has a service life, during which it will not degrade, and it can be collected during that period in the same way as ordinary plastic. If it has not been collected during that period, it ought then to degrade and biodegrade and not to persist for decades.
Recycling – See Recycling Thousands of tons of oxo-biodegradable plastics have been recycled, and I have seen no reports of any adverse experience.
If all the plastic litter could be prevented or collected, there would be no problem, and oxo-biodegradable technology would not be needed. This is not however the case as yet, even in the developed countries.
A recent study published in the Journal of Hazardous Materials AdvancesVolume 10, May 2023, 100309) focused on a recycling facility in the UK, suggests that anywhere between 6 to 13 percent of the plastic processedcould end up being released into water or the air as microplastics — ubiquitous tiny particles smaller than 5mm, that have been found everywhere from the Antarctic to inside human bodies .
The researchers analysed the wastewater generated by the facility. They estimated it could produce up to 6.5 million pounds of microplastic per year, or about 13 percent of the mass of the total amount of plastic the facility receives annually.
The Washington Post (22.5.23) says “This research adds to growing concerns that recycling isn’t as effective of a solution for the plastic pollution problem as many might think. Only a fraction of the plastic produced gets recycled: About 9 percent worldwide and about 5 to 6 percent in the United States, according to some recent estimates.”
“It’s unsurprising that this process could produce microplastics, as the way plastic recycling facilities operate there’s a lot of mechanical friction and abrasion.”
AGRICULTURAL MULCH FILM
A team of scientists from California Polytechnic State University, US, have surveyed strawberry fields after the seasonal removal of film which covers the plants. The researchers discovered up to 213,500 pieces of microplastics – particles larger than 5mm across – per hectare on field surfaces alone.
They also found that plastic pollution reduced soil moisture, microbial activity and plant-available nitrogen, essential for soil health and crop productivity. The findings, presented at the Goldschmidt geochemistry conference in Lyon, France, raise concerns about the long-term sustainability of using conventional plastic mulch in agriculture.
A much better option is to use oxo-biodegradable mulch film. See successful farm trial for oxo film
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