Re-framing the future of food-grade polypropylene
Professor Edward Kosior
Since the 1950s the world has produced around 8bn tonnes of plastic with very little regard, until recent years, as to how we manage its end of life.? This is a reflection of our outdated and exploitative approach to the economy that is based on the belief that we can extract resources boundlessly, use them inefficiently, and discard them without regard for the environment.
As Christiana Figueres, former Executive Secretary of the UN Framework Convention on Climate Change, puts it we are drawing from the planet more than it can regenerate and polluting more than we can clean up.
We need to change the future of plastics in our world as we are well past the time for preventing plastic pollution, yet conversely we also depend on this valuable material for many positive solutions. Reducing food waste being just one such example.
Plastic is not the enemy - how we manage it is. As such, the call for a cap on production of virgin plastics by an international group of scientific experts is only one half of the solution.Closing the loops
Capping virgin plastic production is a sweeping solution that will only have a positive impact if we have in place alternative solutions to bridge the plastics gap. This does not mean not only looking to paper or glass but rather to closing the loop on our current post consumer material streams.?
This starts with identifying those polymers that play the biggest positive part in reducing our wasteful habits. Food-grade PP falls into that remit as it currently is only made from virgin plastic and has a vital role in protecting our food and therefore reducing our food waste.The missing link in plastics recycling
As such being able to rely on an abundance of high-quality food-grade recycled resins would go a long way towards reducing our reliance on virgin PP.? According to ICIS Mechanical Recycling Supply Tracker,? food-grade resins represent only 10% of the global annual capacity of recycled polymers of over 45 million tonnes, of which slightly over 20% is food-grade R-PET compared with just 3% of food-grade polyolefins.
This goes to highlight the urgent need to boost production of food-grade recycled PP given that roughly 20% of the world?s virgin plastic production is PP.
Mechanically recycling PP also means closing the loop on a valuable material that would be wasted if diverted to other end-of-life solutions with higher carbon footprints, such as waste-to-energy or chemical recycling.
As we inch closer to breaching our planet?s natural boundaries there is an urgent need to break down the barriers that are still holding back the likes of food-grade PP recycling. One of the key roadblocks are the stringent challenges of meeting global industrial recycling standards for food-grade resins, particularly given that many transformational recycling solutions are now coming on-stream.Innovative tech for a new era of recycling
To achieve high-quality food-grade PP resin requires eliminating all contaminants from post-consumer waste that could be harmful to human health, as well as proving that the recycled material does not change the food composition, taste, and odour in an unacceptable way.?
This is something that, until recently, was not achievable, hence our reliance on virgin plastics for food packaging. Now we are entering a new era for recycling ushered in by innovative technology, not only to sort post consumer packaging, but also to effectively eliminate any potential residues in the recycled plastics
Closing the loop on food-grade post consumer Polypropylene (PP) is precisely what global multi-participant project, NEXTLOOPP set out to achieve. Now, together with 46 global organisations taking part and using Nextek Ltd?s unique technology, they are trialing prototype food-grade recycled PP (FgrPP) and inert (INRTgrade) resins in injection moulding, extrusion and thermoform package manufacturing.
The project is able to ensure the safety of resins made in its unique process by conducting full scale ?challenge tests? that deliberately add a range of surrogate molecules to simulate the potential contamination of plastics materials at levels hundreds of times higher than typically found in the post-consumer stream, and measuring the rate of decontamination of the recycling process.?
In so doing NEXTLOOPP has demonstrated that the process can strip out any migratable materials to safe levels.Reframing the science
Yet despite these technological advances we may still face the huge constraints of big volume polyolefins recycling, precisely at a time when we need to be accelerating the research and technology developments in this direction.
Scientists Roland Franz and Frank Welle, of Fraunhofer IVV, recently published a paper1 on this very topic, in which they argue that whilst EFSA?s obligatory precautionary principle requires a conservative safety assessment, the over-conservatism in the way food safety factors are calculated during the recycling and migration processes might significantly overestimate the safety risks of recycled plastics in packaging applications and overestimate the risks posed to consumers given the significant improvements in collection, high performance sorting and recycling/decontamination processes.
Both Franz and Welle believe this could pose high, if not insurmountable, barriers to the application of post-consumer recyclates for food packaging; something that risks creating a stranglehold on recycled food-grade resins, especially the polyolefins, and counteracting the circular economy targets.
As Franz and Welle point out, consideration of the input levels of possible harmful contaminants in the recycling stream is a primary pillar in EFSA?s safety assessment framework. The statistical determination of such concentrations in washed flakes as raw input material for super-clean recycling is therefore important.
They go on to say that it is quite obvious that this element is not a static figure and that these levels will change if different re-collection streams are used. Moreover, once re-collection streams are established the input concentrations will reduce over the years due to improvements in consumer behaviour, and also due to changes in the reduced use of hazardous chemicals and their lack of availability to the consumer. However, such data are largely, and broadly, lacking.
Franz and Welle go on to suggest a less conservative and more realistic safety evaluation starting with considering whether all parameters really have to represent the worst-case scenario through to taking the average recyclate amount in an application into account in the exposure scenario instead of 100%.
Currently EFSA assumes the presence of genotoxic substances in the recycling feedstock even though genotoxic substances cannot be used in any goods placed on retail shelves, and that over-estimative prediction models for the migration calculation are used. These worst-case assumptions at every step make the overall evaluation extremely conservative.
Using the modern recycling infrastructure and the latest recycling technologies that we now have, to reframe the science and basic assumptions that regulatory bodies are reliant on, could be a lifeline for food-grade recycled resins and an added incentive to reduce the production of virgin plastics.
It is interesting too to note that the Framework Regulation 1935/2004 from which EFSA draw their evaluations, specifies that ?the use of recycled materials and articles should be favoured in the Community for environmental reasons,? provided that strict requirements are established to ensure food safety and consumer protection.? In addition, ?priority should be given to the harmonisation of rules on recycled plastic material and articles.?
As it stands EFSA?s vital constraints on meeting food contact conditions are much stricter compared with similar standards set by the Food and Drug Administration (FDA) in the USA. The simplified approach taken by USFDA of setting a migration ?threshold of regulation? at 0.5ppb has a built in consideration of consumer exposure to food and packaging types. Whereas EFSA?s end criteria on a case-by-case basis adds an extensive assessment burden for EFSA and recyclers. Under EFSA criteria the threshold for migration for bottled water with recycled PET is 0.1ppb ? an analytical challenge without the use of overestimating migration modelling. Such analytical challenges and highly conservative assumptions have led to EFSA suggesting recycling processes may be safe, however not proven to be safe, acknowledging both outdated information and conservativisms at the same time.
Thankfully, due to cutting-edge advances in recycling technology including state-of-the-art decontamination, specialised recycling processes are highly effective in delivering ?super-cleaned? recycled plastics such as PET, HDPE and PP that have been positively reviewed by USFDA and issued with a ?Letter of Non-Objection?. Nearly 50 USFDA LNO?s have been issued since 2020 showing the speed of the assessment system, along with no in-market incidents which gives testament to a fit-for-purpose risk assessment process by USFDA.Re-defining Circular Recycling
Following NEXTLOOPP?s trials it is now aggregating numerous examples of products into an impressive catalogue of results to demonstrate the suitability of the project?s FgrPP - PPristineTM - and INRT resins.
Whilst these in-depth trial findings show that the process of creating food-grade recycled PP is highly feasible, they also highlight the fact that the recycling process is still more complex than it needs to be due to many current packaging design features. As a consequence NEXTLOOPP is now working in conjunction with industry bodies to advise on new design guidelines for Food-Grade Circular Recycling which must become the new standard for packaging design.Next generation Circular Recycling technology
Certainly there is a raft of new generation technology that recyclers will soon have at their fingertips. From fluorescent markers, artificial intelligence and decontamination techniques to game-changing technology to recycle Polyolefin (LDPE, LLDPE,HDPE,PP) films, which are commonly used for packaging both edible and non-edible goods.
These films, which play a key role in protecting and extending the shelf life of many foods,? are currently missing from the recycling stream as, to date,? there has been no effective decontamination technology to turn them back into food-grade films.?
COtooCLEAN, is yet another Nextek multi-participant project that aims to fill this gap with a unique commercial process that can be integrated into mechanical recycling operations. This innovative process is based on super-critical CO2 (scCO2) combined with green co-solvents to remove oils, fats and printing inks in one single step, as well as very effectively decontaminating polyolefin films back to food contact levels.Reviewing current food safety criteria
As the 2030 deadlines loom for mandates and sustainability related pledges, not to mention for the planet itself, companies need to be able to source an abundance of high-quality food-grade recycled resins. Currently this supply is very limited and we are confident the emerging new technologies will help ease the regulatory bottleneck.
So whilst it is true that investment is needed across the board from collection systems to recycling capabilities to increase the global supply of recyclates to reach industry targets, equally vital is the review of the criteria around food safety regulations, which now has the opportunity to revitalise the entire recycling industry.
In the long run reducing the production of new plastics will go a long way to increasing the value of plastics, boosting efforts to curb plastic pollution and promoting our transition to a circular and sustainable economy, however, for maximum impact our efforts need to be coherent and co-ordinated across the entire plastics ecosystem.
- https://www.mdpi.com/ - Recycling of Post-Consumer Packaging Materials into New Food Packaging Applications?Critical Review of the European Approach and Future Perspectives by Roland Franz and Frank Welle.
» Publication Date: 15/07/2022