Plastic marketed as compostable:

  1. Does not convert into compost (EN13432 and ASTMD6400 require it to convert into C02 gas)
  2. Is designed for a deliberate linear process and is not circular. The material is intended to be wasted by conversion into CO2.
  3. Cannot be re-used, recycled, or made from recyclate
  4. Leaves microplastics in the compost and in the open environment
  5. Does not deal with the problem of plastic litter in the environment
  6. Is not wanted by industrial composters and local authorities.

A survey of more than 1,000 individuals by the “Grocer” magazine in 2019 found that “consumers think that plant-based compostable plastics are the most environmentally friendly packaging materials,” but most consumers don’t realise that “compostable” plastic does not convert into compost. It is required by EN13432 and ASTM D6400 to convert rapidly into CO2 gas, and the last thing the planet needs is more CO2.

There is nothing wrong with composting garden and kitchen waste, but conversion of plastic into CO2 in a composting facility is a linear process where the material is intended to be wasted, and does not address the main problem facing governments today – that is plastic waste which has escaped into the open environment, from which it cannot realistically be collected for recycling, composting, or anything else.

Plastics marketed as “compostable” are not wanted by the industrial composters or local authorities.

As from 1st January 2024, the city of Ann Arbor, Michigan (pop. 124,000) will not accept plastic in its composting facilities.  City officials say they aim to reduce windblown litter at the site and the amount of contamination in the final compost. “Compostable” plastics can get confused with petroleum-based plastics and end up in the recycling stream, officials say. These lightweight plastics also rise to the top of compost piles and are swept away by winds leading to litter.

The city says it recognizes this change may be frustrating to those who rely on previously advertised compostable plastic products, but it emphasizes the contamination and litter the items cause at compost facilities. This includes plastic kitchen compost liners –“ items that will no longer be accepted, as they pose the greatest challenge,” according to City officials.

According to the Daily Mail on 30th December 2022 new research by “Sourceful” a Manchester-based supply chain transparency consultancy says that “marketing compostable plastics as good for the planet is ‘greenwashing’” making things appear more eco-friendly than they are.

Sourceful analysed more than 20 materials, including “compostable” plastic and normal garbage bags.  It found “compostable” bags have nearly twice the global warming impact of traditional plastic. Also, “compostable” bags can only properly degrade under high temperatures in special processing plants, but they’re mostly discarded in general waste before being sent to landfill, where they release methane. Ordinary plastic bags, [and oxo-biodegradable plastic bags] on the other hand, emit very little greenhouse gas in landfill because they are relatively inert.”

What is compostable plastic?  This term is used to describe a material that can undergo biological degradation in a compost facility at a rate consistent with other known compostable materials, leaving no visible (toxic) residues. However the term is misleading, because it is often used interchangeably with ‘biodegradable,’ and it suggests that the plastic converts into compost – which it does not.

“Compostable” plastics are marketed for food packaging, bags, cups, plates, cutlery and bio-waste bags.

Sourceful researchers used the European Commission’s Environmental Footprint 3.0 datasets, and examined greenhouse gas emissions of each product’s lifecycle – raw material extraction, film production and end-of-life stages including disposal.  When expanded to other impact categories such as water use and land use, the gap widened to approximately 2.5 times worse than traditional virgin plastic.

On 14th November 2022 the UK Environment Minister said “HM Government is not currently providing any specific support for the development of compostable potato starch bag packaging and have not evaluated the commercial viability of using compostable potato starch bag packaging by government agencies.”

“Currently there is insufficient industrial composting capacity throughout England to manage compostable plastics at end of life and 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.  Therefore, our focus will be on reducing unnecessary consumption and working towards a circular economy, not composting of plastics.”

The Co-op supermarket should stop marketing plastic bags as compostable.


A study by the University of Bayreuth  shows that “finished compost from composting plants contains a large number of biodegradable plastic particles. Also, applicable legal and certification standards (EN13432, ASTM D6400 etc) are not violated by the sizes and quantities of the particles detected, so this calls into question the contribution of these standards to effective environmental protection.”

On 15th July 2020 a report appeared in “Waste Management” Vol. 113, Pages 312-318. The conclusions were:

  • In many cases, plastic bags are being replaced with compostable plastic bags.
  • Industrial composting processes do not completely remove film fragments.
  • Compost is thus a potential source of fragments from compostable plastic bags.
  • Compostable plastic fragments are then deteriorated in soil to microplastics.
  • Compostable microplastic results in an increased number of aflatoxigenic fungi.


The UK Environment Minister continued “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.”

The EU Commission say (Communication 30th November 2022 (COM(2022) 682 final)) “in most of today’s biobased plastic products such as single-use packaging, the carbon initially taken up from the atmosphere is quickly released back” and “As biodegradable plastics are predominantly used in relatively short-lived applications such as food and beverage packaging, the resources used to produce these products are rapidly lost.”

Sending plastic to a composting facility is a deliberate linear disposal route, as EN13432 requires it to convert into CO2 gas within 180 days. The plastic is therefore intended to be wasted, and conversion of organic materials to CO2 is not ”recovery.”

A material that converts into CO2 not into compost, cannot be described as compostable, and action should be taken against companies who are so describing it.

Also, because there are very few industrial composting facilities available, the German courts in Güthoff v Deutsche Umwelthilfe (2014) have held that it is deceptive to market plastic as “compostable.”  Many areas do not have industrial composting plants, and the Welsh Government has refused to invest in them. Bio-based plastics are therefore going to landfill rather than to composting.


Bio-based “compostable” plastic is also inconsistent with a circular economy because it cannot be re-used or recycled, nor can it be made from recyclate – three very important points which the EU Commission seem not to notice. They are also much more expensive as compared with conventional plastic – an important point at a time when most of the people of Europe are struggling with a cost-of-living crisis.


Many consumers do not know that “compostable” plastic is tested to biodegrade in an industrial composting facility – not in the open environment. In November 2019 a Danish court ruled in Ellepot v Sungrow that “compostable” PLA plant pots must not be described as biodegradable – because they are not biodegradable except in the special conditions found in an industrial composting facility.

The EU Commission say that “plastics labelled as ‘biodegradable’ must always specify the receiving open environment for which they are intended and the required timeframe for their biodegradation, in terms of weeks, months or years. Therefore, plastic certified according to EN13432 for biodegradation in an industrial composting facility (not in the open environment) should not be described as “biodegradable” and the Commission should take action against companies who are doing this.


The EU Commission say that “To fight greenwashing and avoid misleading consumers, generic claims on plastic products such as ‘bioplastics’ and ‘biobased’ should not be made.”

Although these plastics are marketed as “bio-based” they can contain up to 50% oil-based material, but this is hardly ever mentioned in the marketing material.

The Commission are concerned about deception of the public by marketing a plastic product as “biobased” when the product may contain a substantial component of oil-based plastic. They say “In order to avoid misleading consumers, claims should only refer to the exact and measurable share of biobased plastic content in the product, stating for instance, that the ‘product contains 50% biobased plastic content.’ Action should be taken against companies who are not making this clear.

The Commission added “Documenting the use of biomass through a chain of custody and attributing a share to end-products through mass balance accounting is a method which is not considered suitable for confirming the actual share of biobased content.”

These plastics are often marketed as “renewable” as well as “compostable” but this ignores the fossil fuels used in the agricultural production process by the machines which clear the land, plough the land, bring the seeds to the farm and sow them, harrow the land, bring the fertilisers and pesticides to the farm and spread them, harvest the crop and transport it to the factory, and by the machines which polymerise the raw material.



The Commission also say that “In most cases, the production of biomass requires the use of natural resources such as land and water and the use of chemicals such as fertilisers and pesticides. Therefore, producing plastics from primary biomass can lead to direct or indirect land-use change, which in turn can result in biodiversity loss, ecosystem degradation, deforestation and water scarcity, as well as competition with crops intended for human consumption.”

The Commission are therefore discouraging the use of corn or potato starch to make plastics, (as distinct from materials from non-food sources such as algae, being produced by companies such as Eranova in France).

On 11th September 2003 a Report to the Australian Government by the Nolan-ITU Consultancy concluded that: “biodegradable plastics based on polyolefins (ie oxo-biodegradable plastics) contribute to the amount and nutritive value of the compost because much of the carbon from the plastic is in the form of intermediate oxidation products, humic material and cell biomass.

This is in contrast to hydro-biodegradable polyesters (e.g. starch-based) that biodegrade at rates comparable to purified cellulose. At the end of the commercial composting process, all of the carbon from the latter has been converted to CO2 so there is a contribution to greenhouse gas levels but not to the value of the compost.”

The same Report concluded that “degradable polymers manufactured from renewable resources (e.g. crops) have greater impacts upon eutrophication due to the application of fertilizers to land.”


So why do the Commission think that biobased plastics are at all useful? They wish to discourage the use of fossil resources to make plastic, but they accept that biobased plastic can itself contain 50% biobased plastic content. Also, the production and polymerisation of feedstock, even from vegetable waste, uses fossil fuels and generates emissions.

The EASAC Report of March 2020 says that “replacing PE by a bio-PE would require almost all (93.5%) of global wheat production” which is completely unsustainable.

By contrast, ordinary plastic and oxo-biodegradable plastic are made from a by-product of oil and gas which are extracted for fuels. Until the day arrives when they are no longer needed for fuels, it makes sense to use the by-product, and there is no present need for biobased plastics, even if they were useful.

“Compostable” resins are worse than conventional or biodegradable plastics when it comes to oxygen transmission-rate or moisture vapour transmission-rate. These resins are also water sensitive, and their physical, optical, mechanical, and chemical properties are inferior.


The Commission also say that “More work is needed to assess and reduce the net greenhouse gas emissions of biobased plastics compared to their fossil-based equivalents, taking into account the lifetime of recycling applications and the possibility of multiple recycling.” In fact, Life-cycle Assessments by Intertek show that ordinary plastic and oxo-biodegradable plastic have lower net greenhouse gas emissions than biobased plastics.

See also Sourceful analysis above


The Commission seem to think that biobased plastic is useful for transporting food-waste for processing, but the composters and local authorities do not want it.

In Parliament on 14th November 2022 the UK Minister for the Environment confirmed that “evidence suggests these materials are often stripped out at the start of the process and landfilled or incinerated”

Epsom & Ewell Borough Council in the UK tells its residents:

“We used to ask you to use bio-liners to line your food waste caddy, but the food waste recycling companies found that bio-liners compost down much more slowly than the food. That slowed the recycling process and made it much more expensive. They tried dredging the bio liners out of the food waste, but the sticky bio-liners got tangled around the dredging equipment. Cleaning them off was very expensive, so they found that using ordinary plastic bags was, overall, much more cost-effective.”

  • The City of Exeter UK has also rejected it
  • And the City of Toronto, Canada
  • In January 2020, the industrial composters of Oregon gave 9 reasons

why they did not want it

  • Then the SUEZ waste-management company
  • Then a devastating exposé on Netherlands television
  • And another TV exposé in Canada about how compostable plastics are typically not being composted but instead sent to landfill or incineration.


The Commission makes an unsupported claim that biobased plastics can stimulate the creation of jobs, but this is not likely to be the case without subsidies out of taxpayers’ money. Also it fails to recognise job losses in the conventional plastics industry, and extra costs for reorganizing the supply chain, re-equipping factories, and retraining the workforce.


Home composting of plastic should not be encouraged:

“HOME COMPOSTING” is Greenwashing

A study by University College London, published in the journal “Frontiers in Sustainability” on 3rd November 2022 says that calling plastic packages “home compostable” is a greenwashing tactic designed to take advantage of consumer interest in environmental sustainability.

The study found 10% of people can effectively compost at home, but for the remaining 90% the best place to dispose of compostable plastics is in landfills. “Most compostable plastics end up in landfill or are burnt,” the researchers found.

The results were drawn from 9,700 people across the UK who completed the Big Compost Experiment survey study. Those participants were evaluated on their understanding of plastic waste, and 1,600 implemented composting at home with plastics labelled as “compostable.”

The results showed that no specification was reliably home-compostable, and the conclusion is that home composting “is not at present a viable, effective or environmentally beneficial waste processing method for compostable or biodegradable plastics in the UK.

The report noted that “When “compostable” plastic gets into food waste, it contaminates it, blocking the recycling process and resulting in more production time, energy and waste.”

In the UK Parliament the Government were asked what assessment they had made of the compostability of plastics certified as home compostable.  On 2nd December 2022 the Environment Minister Lord Benyon replied:

“HM Government notes the findings from UCL’s study into the home composting of plastics and will use this to inform our evidence base. The study has shown that home composting is not a viable destination for managing plastic waste.”


The EU Commission say that “Home composting is more challenging in terms of ensuring full biodegradation of compostable plastics and requires a greater degree of precaution. Compliance with standards for industrial composting does not imply decomposition also under home composting.”

They continue “Home composting for plastics not covered by EU rules should only be considered in the context of specific local conditions under the supervision of the relevant authorities and provided that the use of such plastics has clear added value.”

This makes no sense at all. How can a compost pile at the bottom of the garden be “supervised by the relevant authorities” (whoever they may be) and how can it be affected by “specific local conditions?” How can an expensive plastic bag add value when it simply converts to CO2 gas, not compost, and could be the source of microplastics? Why in any event would anyone buy these bags when they could take kitchen waste to the bottom of the garden in a bucket?


In October 2022 the French Agence Nationale (ANSES) said that “Even for those plastics claiming to be “biosourced, biodegradable or compostable” it is not guaranteed that they will degrade completely in domestic composters, especially since it is difficult to control the operating conditions. Therefore, when an individual spreads compost in his vegetable garden to grow vegetables,  contamination of the environment or crops cannot be excluded.”

“This contamination can come from the different constituents of the materials, or from microplastics resulting from their degradation. The constituents concerned may be polymers, residual monomers, additives or inorganic fillers presenting potential hazards to both human health and the environment.”

“ANSES therefore recommends that no plastic, even if labelled “biodegradable” and/or “compostable”, be placed in domestic or collective composting facilities.”

The biodegradation of plastic bags in domestic composting makes little or no contribution to the formation of humus because, in accordance with the biodegradation tests of these materials (NF T 51 800) standard, at least 90% of the carbon organic dioxide is converted into carbon dioxide.”

Worse still, there is a danger that the plastic may have been contaminated by pathogens from putrifying food, and temperatures in a home compost may not be high enough to kill those pathogens.


There are 21 reasons why plastic marketed as “compostable” is not useful