Biodegradable & Compostable Greenwashing Michael Stephen Column

Compostable Greenwashing, Home Composting – More Greenwashing (FREE)

Today Michael reviews reports showing that compostable plastics are greenwashing. This is a FREE article.


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. 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, on the other hand, emit very little greenhouse gas in landfill because they are relatively inert.

The main applications of “compostable” plastics include food packaging, bags, cups, plates, cutlery and bio-waste bags.

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

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.

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

“HOME COMPOSTING” – More Greenwashing

Another study, 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 “most compostable plastics end up in landfill or are burnt.”

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 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.”

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

For composting generally see

Michael Stephen

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.

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