In 2019, researchers at the University of Plymouth buried a plastic bag labeled “biodegradable” in the ground. Three years later, they dug it up. The bag was intact. It was still holding a load of groceries.
The study, published in the journal Environmental Science and Technology, had tested five types of bags available in British supermarkets: one made of conventional plastic, one “oxo-biodegradable,” one “biodegradable,” one “compostable,” and one made of high-density polyethylene. They had exposed them to three natural environments: open air, soil and seawater. After nine months in the open air, all had fragmented. But in the soil and sea, the “biodegradable” bag, the “oxo-biodegradable” bag and the conventional plastic bag were still functional after three years. Imogen Napper, the researcher who conducted the study, said she was “really amazed that any of those bags could still hold up.”
The “compostable” bag had behaved differently: in the sea it had disappeared in three months, but in the ground it was still there after 27 months, even though it could no longer support the weight.
The study was challenged. European Bioplastics, the industry association, objected that the bag labeled as “biodegradable” did not have certification in accordance with the European standard EN 13432, and therefore the results did not apply to properly certified products. The association acknowledged that only the “compostable” bag in the study was actually certified. This is a relevant point: it distinguishes between self-attributed labels and verified certifications. But it is also the heart of the problem, because a consumer in the supermarket does not know the difference.
And the difference is substantial. “Biodegradable” means that a material decomposes through the action of microorganisms. It does not specify where, in how long, or under what conditions. A tree trunk is biodegradable. So is a newspaper. The label does not guarantee anything about the rate or conditions required. “Compostable” is more specific: according to European standard EN 13432, a compostable material must decompose at least 90 percent within six months in an industrial composting facility, at temperatures of about 60 °C and with controlled humidity. Not in the garden. Not in a landfill. Not in the sea. In an industrial plant.
The analogy is with cooking temperature. “Bakeable” tells you nothing: any food is bakeable. “Bakeable at 180°C in a ventilated oven for 40 minutes” is an instruction. “Biodegradable” is the first case. “EN 13432 certified compostable” is the second. The label on the bag at the supermarket usually says only the former.
In Italy, the situation has an added complexity. As of January 2022, Legislative Decree 116/2020 has made separate collection of wet waste mandatory in all Italian municipalities, two years ahead of the European obligation. Collection bags must be compostable and EN 13432 certified. Italy has the second largest composting capacity in Europe after Germany, and 80 percent of the population is connected to organic waste collection.
But the numbers hide a structural problem. As of 2022, according to data from the Italian Composters Consortium compiled from the ISPRA Waste Report, 675 Italian municipalities had not yet activated separate collection of wet waste, totaling more than 900,000 inhabitants. And even where collection works, more than 56 percent of the organic fraction is treated through processes that include an anaerobic digestion step. Compostable bags do not degrade under anaerobic conditions-they must be mechanically removed prior to processing. The EN 13432 standard, which defines the compostability of those bags, dates back to 2002, when the only available technology for treating organics was industrial aerobic composting. The technology has evolved. The standard no.
A certified compostable bag, properly thrown in the wet, in a municipality that has activated collection, can end up in a plant where it still has to be separated because the process is not what it was designed for.
The regulatory framework is changing. France is the first European country to ban the use of the term “biodégradable” on products and packaging: Article 13 of the AGEC law, implemented by Decree 2022-748, prohibits it from 2022. Industry federations have appealed. The Conseil d’État upheld the ban.
The European Union is moving in the same direction. The ECGT (Empowering Consumers for the Green Transition) directive, the same one that in the previous article in this column we saw banning offset-based “carbon neutral” labels, explicitly includes “biodegradable” in the list of generic environmental claims banned without demonstration of “recognized excellent environmental performance.” As of September 2026, declaring a product “biodegradable” without a certification to prove it will be a banned business practice in the EU.
In Italy, the Italian Antitrust Authority has already sanctioned cases of unverified environmental claims on products labeled as “biodegradable”: diapers advertised as “biodegradable and compostable” that turned out not to be compostable due to the presence of non-biodegradable polymers, bags declared “100 percent biodegradable” with extremely long biodegradation times.
This column keeps finding the same mechanism. “Natural gas” sounds clean but is a fossil fuel. “Carbon neutral” sounds responsible but can mean offsetting without reduction. “Sustainable” in the EU taxonomy includes sources that most Europeans would not classify that way. “Biodegradable” sounds like a promise of disappearance but does not say where, when, or how.
The next time you read “biodegradable” on a bag, on packaging, on a product, the useful questions are three: biodegradable where? In how long? Under what conditions? If the label doesn’t answer, as of September 2026 in the European Union it can no longer be there.
