Two years ago, British researchers delivered the results of an unprecedented experiment. After three years spent buried in the ground, so-called “biodegradable” plastic bags have quite simply survived. The results of this experiment had given a lot of reaction on the web, but remain questionable.
Bags more resistant than expected
In 2015, scientists from the University of Plymouth (United Kingdom) buried several plastic bags in a garden. More precisely, these were five bags qualified as “biodegradable”, “oxodegradable” or even “compostable”. In 2019, these same researchers published a study evoking that after three years, the majority of these bags have shown themselves to be rather resistant. A few weeks after the publication of the study in question, the magazine GEO had questioned Guy César, ex-agricultural engineer and specialist in biodegradable materials. He is president of the association SerpBio, the objective of which is to help SMEs and SMIs to easily access “biodegradable” certification for the materials they place on the market.
According to the expert, the British study makes “no sense”, because the researchers notably tested two oxodegradable bags. These are conventional polyethylene products to which transition metals have been added, the purpose of which is to accelerate the degradation in the presence of oxygen. In fact, a biodegradable material always requires very specific circumstances in order to biodegrade (precise environment, temperature, etc.). An oxodegradable bag will therefore not degrade in water or soil.
Moreover, fragmentation and biodegradation should not be confused. Remember that in the case of biodegradable bags, the material undergoes fragmentation into extremely small particles. These are then attacked by microflora and microfauna ecosystems, bio-assimilated and transformed into carbon dioxide or methane.
Biodegradable bioplastic: is it greenwashing?
Guy César nevertheless evokes the fact that oxodegradable bags are subject to a certain biodegradation. On the other hand, this one only intervenes after ten to fifty years depending on environmental conditions. Thus, oxo-biodegradable materials are not environmentally sustainable. For the expert, the term “organic” associated with these packaging is simply greenwashing, a marketing process allowing certain companies or organizations to fraudulently portray themselves as responsible.
In a Facebook post on March 22, 2021, the militant media Mr Mondialisation castigated a campaign currently led by Elipso, the professional association representing plastic packaging manufacturers in France. For the media, bioplastic is a myth and the poster visible below is misleading.
Here is also a video published by Le Monde in 2019, recounting the experience of researchers at the University of Plymouth: