Compostable bioplastics: the items of fake news claiming that they harm the environment

Of course this is what the scientific evidence says, but it is confirmed by the day-to-day experience of those in the industry. At the same time this is also recognised by Italian legislation, and it has long been regulating them and promoting their use and joint recycling with organic waste (better known in Italian homes as 'wet waste'). This is how they can be turned into compost, a natural fertiliser that can be used in place of chemical fertilisers, which puts nutrients into the soil, restoring its fertility. Something not at all insignificant when we remember that Italy, together with Spain, is the EU country having the most degraded soil. Soil that is desertified and at further risk of desertification, as reported by the World Atlas of Desertification produced by the European Union publications office.

Major expansion in the sector has helped us become increasingly familiar with these materials and the many flexible and rigid packaging materials of which they are made today - from the now famous bio shopping bags, to bags for the collection of wet waste, plates, crockery, cutlery, beakers/cups and beverage capsules.

And yet, despite everything, many false beliefs still persist, and at least partly affect the way in which these products are generally perceived. Whether this is through ignorance or deliberate deception is of little consequence. We must therefore take a close look at the most contentious issues and provide what is needed for them to be properly discussed. Accordingly we have focused on 10 particularly frequent untrue statements. Let’s look at these in detail.

In 2021 it was estimated that the amount of land used for the production of bioplastics was 0.01% of the world's agricultural area (https://docs.european-bioplastics.org/publications/EUBP_Facts_and_figures.pdf), that is just 700,000 hectares. To put this figure into context, the number of hectares used for plant crops for industrial purposes is enormously higher. Worldwide, a forest area of 1.15 billion hectares, i.e. 1,640 times more, is used just for timber and other products (https://www.fao.org/3/ca9825en/ca9825en.pdf).

What is more, the bioplastics industry has always been committed to developing technologies that use waste and scrap to produce such materials.

It is often said that bioplastics use up valuable food raw materials. Most frequently mentioned is starch, a raw material that is also used by the Italian bioplastics sector. In this respect it should not be forgotten that starch has always been used for non-food purposes. According to 'Starch Europe' (https://starch.eu/the-european-starch-industry/), 44% of starch production in the EU and the UK is for industrial purposes. Of this percentage, the paper and corrugated products industries (32%) are the main users, followed by the pharmaceutical and chemical industries (7%) and other non-food sectors (5%). Bioplastics are not even mentioned as a specific starch-consuming industry.

The distinctive and defining characteristic of compostable bioplastics is not their origin (their renewability), but their end-of-life (their compostability). There are many compostable bioplastics on the market that have a high renewable raw material content. It is to be hoped that European regulations will increasingly push for renewability so that the share of bioplastics derived from fossil sources is reduced. Unfortunately this is not how things stand at the moment, and this favours the market for monomers and polymers derived from fossil sources, often produced outside Europe.

Having said that, this would seem to be a rather odd accusation: by the same logic we should also criticise hybrid cars because they run partly on petrol (we are in a transition stage). In the same vein it is inconsistent to accuse bioplastics of competing with agricultural production, using up renewable raw materials, and at the same time accuse them of not using enough of these. In any case, whatever the origin of their components (from oil or agricultural resources), bioplastics have to be fully compostable to meet the stringent requirements of standard EN 13432.

As for the presence of hazardous chemical additives: to be considered compostable products have to be certified according to EN 13432, which among other things includes an ecotoxicity test. This ensures that products (in their final form, that is including any additives) release no toxic substances or heavy metals that might compromise compost quality. On top of this, many compostable bioplastics are naturally resistant to liquids and so do not need any chemical treatment when used to produce articles that are in contact with food

 (https://www.polimerica.it/articolo.asp?id=26662).

LCA (Life Cycle Assessment) studies refute this:

https://www.sciencedirect.com/science/article/abs/pii/S0956053X17308760. Compostable and renewable bioplastics are an opportunity to decarbonise the economy and promote circular systems.

If indeed they did have greater environmental impact than conventional materials, it would be hard to explain why the EU is promoting the bioeconomy and renewable and compostable products (https://knowledge4policy.ec.europa.eu/bioeconomy/bioeconomy-strategy_en). In fact Europe provided almost 1 billion euro of funding for more than 130 research projects on biobased/biodegradable plastics between 2007 and 2020 alone.

Putting compostable bioplastics in with the wet waste is simply a response to European law. In fact they were developed in response to the concept of 'packaging that is recoverable in the form of compost' in Directive 94/62/EC. If this is their purpose and their fate at the end of their lives, then it is hard to see how they should be disposed of, if not specifically with domestic wet waste (OFMSW), with the production of compost.

The collection of compostable bioplastics together with wet waste is explicitly envisaged by European regulations (https://eur-lex.europa.eu/legal-content/IT/TXT/?uri=CELEX%3A32018L0851). These envision the compulsory differentiated collection of OFMSW by 31/12/2023. Italy has brought forward the timing by making it compulsory from 1/1/2022. ISPRA reminds us of the benefits of this model (wet waste/ compostable bioplastics) in its annual report on urban waste (https://www.isprambiente.gov.it/files2022/pubblicazioni/rapporti/rapportorifiutiurbani_ed-2021-n-355-conappendice_agg18_01_2022.pdf )

Growth in differentiated collection of the wet fraction has undoubtedly become a further stimulus to the use of biodegradable and compostable bags, as they are suitable for recycling organic waste. Thus the elimination of non-compostable plastic packaging may help to improve biological processes and increase the quality of compost produced by biological treatment plants".

As part of the programme agreed between Assobioplastiche, CIC, CONAI and Corepla, tests to check the behaviour of compostable bioplastics have been carried out on both a lab scale and under real conditions (full scale, that is at processing plants) between 2016 and 2017. Both flexible and rigid compostable bioplastics disintegrated and/or completely disaggregated in both the lab scale and full-scale tests. The tests were performed in composting plants as well as in integrated plants (anaerobic digestion and composting).

In 2021 the CIC (Consorzio Italiano Compostatori) carried out monitoring on behalf of Biorepack at 30 organic recycling plants and came to the same conclusions.

It has been demonstrated by a study by the University of Wageningen (https://research.wur.nl/en/publications/the-fate-of-compostable-plastic-products-in-a-full-scale-industry) that, in a Dutch organic waste treatment plant, certified compostable products tested to EN 13432 biodegraded within a maximum of 22 days. Even in the case of anaerobic digestion with a subsequent composting phase, tests carried out as part of the programme agreed between Assobioplastiche, CIC, CONAI and Corepla have shown that complete biodegradation occurs in approximately 55-63 days.

It should not be forgotten that, as stipulated by BAT (Best Available Techniques), the right treatment time (9-10 weeks for composting plants) is crucial to quality organic recycling. Cycles that are too short do not allow compostable materials to be degraded effectively, increase plant waste and worsen the quality of the compost produced.

48.1% of the organic fraction is treated in composting plants and 46.8% in integrated plants (in which the composting stage follows the anaerobic digestion stage). Only 5.1% is treated in anaerobic digestion-only plants (ISPRA data). So 94.9% of treatment processes are suitable for composting and biodegrading compostable bioplastics according to the data and tests (lab scale and full scale) carried out according to the programme agreed between Assobioplastiche, CIC, CONAI and Corepla, and the monitoring by CIC/BIOREPACK in 2021.

In addition, there are articles (https://doi.org/10.1016/j.biortech.2022.127224) which demonstrate that even under anaerobic conditions (both full scale and lab scale) the main bioplastics currently on the market degrade to biomethane with an excellent yield. A recent study by an international team of researchers has noted the strategic role of bioplastics for quality recycling of the organic fraction ("The bioplastics within organic municipal waste are a critical component for the future of waste management with particular reference to the quality of the final products, i.e., digestate and compost";

https://www.sciencedirect.com/science/article/abs/pii/S0921344922005274).

In any event, integrated treatment is the most beneficial because it 'closes the circle'. Not only does it not stop at energy recovery, it brings about true organic recycling with the production of compost - and this, as is well known, is the preferred option in the pecking order of treatments being championed in Europe.

The CIC (Consorzio Italiano Compostatori) states exactly the opposite (https://www.compost.it/wp-content/uploads/2019/08/Comunicato-stampa-1-Sacchetti-biodegradabili-otto-verit%C3%A0-per-una-migliore-raccolta-dell%E2%80%99umido.pdf?ectid=196927&ectmode=campaign&ectttl=7): "The plants employed in the recycling of organic waste have been confirmed to be an appropriate and efficient system for dealing with biodegradable and compostable plastic packaging. Almost all plants (with a few exceptions, due to particular pre-treatment systems), both composting-only biological processes and integrated digestion/composting processes, accept and can deal without any problems with the compostable plastic products present in the organic waste stream coming to them".

The real question that then needs to be asked, is about the layout of some plants that on closer inspection are found to discard not only compostable bioplastics, but also the biodegradable solid waste normally found in organic matter. This includes wood, nut shells and egg shells. These plants consciously decide to select only certain materials for processing, discarding all the rest (solids, including compostable bioplastics). Also we need to ask about plants that have very high rejection rates because of the very large amounts of non-compostable materials in the wet waste collected, or because of processing techniques or treatment times that do not comply with BAT (Best Available Techniques), and are forced to resort to pre-treatment systems that end up preventing even compostable materials from being recycled. Approximately 15 per cent of materials for recycling are currently lost because of such pre-cleaning and separation operations caused by the presence of large amounts of non-compostable materials, or because of handling techniques and treatment times that are not BAT-compliant.

BIOREPACK has conducted five video interviews with the managers of five composting plants in various parts of Italy:

 (https://biorepack.org/comunicazione/news/la-parola-agli-impianti-di-compostaggio.kl ).

Just listening to what the managers of these plants themselves have to say is to understand that the claim that flexible or especially rigid bioplastics are a problem is wholly unfounded. On the contrary, they behave like grass cuttings and prunings and should be treated as such.

No-one in the compostable bioplastics supply chain in Italy has ever promoted the total replacement of single-use plastics with single-use bioplastics. On the contrary, only those products designed as specific solutions to the problems caused by the presence of non-compostable materials in wet waste (bags, dishes, capsules, etc.) have been promoted. If we take the case of shopping bags, for example, - the sector in which compostable products are most widely used - the Italian legislation focusing on the combination of reusable bags/compostable bags has brought about a 58% reduction in the total number of shopping bags in circulation between 2010 and 2021 (http://www.assobioplastiche.org/assets/documenti/news/news2022/15giugnoLa%20filiera%20dei%20polimeri%20compostabili%20-%20Dati%202021.pdf ).

A similar reduction also applies to the single-use products covered by the UAS Directive - https://eur-lex.europa.eu/legal-content/IT/TXT/PDF/?uri=CELEX:32019L0904 - in particular plates and cups, which saw a reduction in volume of 55% between 2016 and 2021.

With regard to litter, the abandonment of waste in the environment, no products should be disposed of in the environment in an uncontrolled way. All products made of any material must be collected and recycled. Paper must be collected with paper, cans with aluminium, glass bottles with glass, etc. EN 13432-certified compostable bioplastics, with the appropriate disposal instructions, are designed to be collected together with domestic wet waste and composted in organic recycling plants, not to be disposed of uncontrolled in the environment.

This applies to all biodegradable materials. For example, there is no evidence that the biodegradability of paper (which consumers are well aware of) is a factor in its uncontrolled scattering. Neither does it appear that banana peel, or that of any other fruit, is thrown on the ground because it is biodegradable. On the contrary, such behaviour is immediately condemned by the public. Testing biodegradation in the sea for items used in fishing, such as mussel nets, is something else altogether. In this specific area, innovation in the field of inherently biodegradable plastics has made great strides.

Zimmermann's article "Are bioplastics and plant-based materials safer than conventional plastics? In vitro toxicity and chemical composition"¹ has often been quoted to argue that bioplastics contain toxic additives and are therefore no safer than plastics.

It is worthwhile clearing the air of misunderstandings arising from articles with suggestive titles that are unfortunately discussed and used in non-scientific contexts. There is no ranking of materials in terms of safety, and bioplastics have never claimed to be safer than other materials. A material is either safe (if it meets legal requirements, like bioplastics) or it is not.

In particular, all materials (plastics, paper, aluminium, etc.) and specifically all food contact materials (FCM), whether compostable or conventional plastics, must meet the strict requirements imposed by European regulations². These provide a list of "safe" substances that are permitted for use in the manufacture of plastic or bioplastic FCMs, and specific migration limits (the maximum amount of substances that can migrate into foodstuffs). To define a product (plastic or bioplastic) that complies with current regulations as toxic, all the more so on the basis of a method of conducting toxicity tests that has not been validated and differs from the official method, is to discredit not only plastics and bioplastics, but also the responsible technical-scientific bodies, namely the EFSA (European Food Safety Authority) and the ECHA (European Chemicals Agency). This is the thinking of conspirator theorists with ulterior motives that deserves no credence and overlooks the important function of plastics and bioplastics in contact with food of safeguarding its organoleptic characteristics and hygiene and food safety requirements. What is more, as mentioned above, the study is based on an irrelevant premise (whether or not bioplastics are safer than plastics) because bioplastics have never claimed that they differ from plastics in terms of greater or lesser food safety (they are both safe when compliant with the legal requirements), but only that they do so in terms of their end-of-life biodegradability and compostability characteristics.

In short, all materials that are suitable for food contact and meet the relevant legal requirements are safe.

¹ Zimmermann et al. (https://www.sciencedirect.com/science/article/pii/S0160412020320213)

² EU Regulation No. 1935/2004 and EU Regulation No. 10/2011

This aspect is specifically addressed by current standards (cited below), which not surprisingly provide for specific ecotoxicological tests to rule out the possibility that what is left over from the biodegradation process might damage the environmental medium involved. Certification is therefore a safety precaution, and materials that are certified according to these standards do not present these problems.

In particular, the standards on the compostability of packaging and plastics (e.g. EN 13432, ISO 18606, ISO 17088), as well as those relating to biodegradable mulching sheets (EN 17033, ISO 23517), provide for ecotoxicological tests to be carried out on the medium (compost or soil) in which the material under study is made to biodegrade. A large excess of the material under investigation in comparison with the concentration normally used is added and biodegradation is induced. If the material releases persistent toxic compounds during biodegradation, these accumulate in the medium and the test fails. The tests carried out at the end of the biodegradation process are therefore designed to reveal any effects caused by an accumulation of persistent substances having a toxic effect, and, if there are any, the material tested fails the tests and therefore cannot be certified.

In short, a material either passes the ecotoxicological tests (if it meets current standards, as bioplastics do) and is then certified, or it does not, and only then do the problems of toxic intermediates generated during the biodegradation process arise.

21 days is too short a time to obtain a mature (i.e. stable) compost that has no adverse effects on plants and soil, between 45 and 90 days are needed³ . When 21 days is mentioned, this relates to the stage of the composting process in which the compost is transferred from the initial parts of the plant (where the first thermophilic bio-oxidative stage takes place) to other areas where it is stored and matured. So after 21 days the composting process is incomplete and in fact, if the product is screened after just 21 days, several larger pieces of waste may not have fully disintegrated. Here we are not just talking about compostable bioplastics, but also gradually biodegradable materials such as bits of wood, branches, bark, etc. Obviously this does not mean that the materials are not biodegradable when composted, but that after 21 days the composting process is not finished and is still ongoing.

In short, when it is said that bioplastics do not biodegrade in 21 days (first stage), this overlooks the fact that the composting process comprises two stages that last 45-90 days in all, and that after 21 days even bits of wood, branches, bark, etc., may not be fully biodegraded precisely because the composting process is not yet complete.

³ BAT (Best available techniques) see Ministerial Decree 29/01/2007, published in the Official Journal on 07/06/2007

These claims keep cropping up, but are clearly not supported by data/studies. On the contrary Italian data show exactly the opposite, that is the level of bioplastics in plastics is less than 1%⁴ (which is comparable to, and in fact lower than, that of metals, etc., in plastics), thanks also to the work of Biorepack.

In addition, it should not be forgotten that plastics are a large family of materials, made up of different polymers (polyethylene - PE, polyethylene terephthalate - PET, etc.), each having different properties and which, in order to be recycled, need to be sorted and separated from each other to create uniform flows of polymer which only then can be sent for recycling. So if cross-contamination is brought up, there is indeed cross-contamination even between these conventional plastic polymers (PE and PET, etc.) and not just between biopolymers and conventional polymers. But this is no impediment to their recycling, while it is also true that biopolymers as well can be sorted using optical readers and recycled. Nevertheless, overall the cross-contamination of materials still needs to be thoroughly investigated (for example, the presence of non-compostable materials in wet waste penalises the recycling of bioplastics, causing it to lose more than 14 percentage points⁵) and should not be used as an argument against bioplastics only.

In a word, cross-contamination is nothing more than one of the many often-heard refrains used as a criticism, but obviously without any data to back it up.

⁴ In October 2017 a study examining the quality of recycled plastic materials from 19 sorting plants for differentiated collection and recycling throughout the country, published jointly by Corepla (the Italian Consortium for the Collection, Recycling and Recovery of Plastic Packaging), Consorzio Italiano Compostatori (CIC) and Assobioplastiche (Italy’s Bioplastics and Biodegradable and Compostable Materials Association), showed that compostable plastics accounted for only 0.85% of incoming plastics and that today this figure has fallen further following the creation of Biorepack and the actions that the consortium has promoted.

⁵ More than 10,000 tonnes of compostable bioplastics are actually being diverted away from recycling because of the presence of large quantities of non-compostable materials. This quantity lost from the recycling of bioplastics amounts to about 14 percentage points. Without this serious loss, recycling would already reach and exceed 65%, thus making an effective contribution to the national targets.