Monday, May 29

This researcher put a biodegradable bag in the sea six years ago and it is still intact

Researcher Imogen Napper was 24 years old and studying for her doctorate in 2016 when she came up with an idea that she herself today calls “madness”. She left the campus of the University of Plymouth, a city by the sea in the south of the United Kingdom, and went on a tour of supermarkets and shops with the question: “Do you have biodegradable or compostable bags here?” The department that carried out his studies, and where he continues to work today, is the International Marine Litter Research Unit of this university, a pioneering center and one of the most advanced in the world in analyzing the impact of plastics on the oceans.

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“In conversations with my supervisor, a very interesting debate arose about compostable and biodegradable plastic; it was becoming more and more popular and we wanted to study when these products break down. Is it a matter of days, months, years?” he tells by phone from Plymouth. His supervisor was Richard Thompson, the researcher who first coined the word ‘microplastic’, and who has spent his entire life as a scientist analyzing the effects of plastics in marine environments.

The team of researchers decided to do an experiment to find out. Five biodegradable and compostable bags that the young scientist had collected from the city’s supermarkets were placed in three different places: buried under the ground at the university, in the water at Queen Anne’s Battery and in the open air, on one of the campus walls.

Napper says today that he went to see the bags every month, to check what condition they were in. The idea was to check for deterioration by surface loss and disintegration, as well as more subtle changes in chemical structure.

In 2019, three years later, they published a pioneer study in which they surprised with a photo in which the young student was holding one of the dirty biodegradable bags, but intact and full of products. Only the compostable ones had disintegrated in the sea after three months. However, and although they showed signs of deterioration, those deposited underground were still there. “After three years she was really surprised that the bags could still carry groceries, which is the most amazing thing for a biodegradable bag. When we see something with that label, I think we take it for granted that it will degrade more quickly than a conventional one, but our study shows that it does not seem that way, “explained Napper then.

The young woman has continued to go since then to see the bags. At the beginning of July, the scientist posted on the social network Twitter a photo very similar to the one she had posted six years ago. She with a life jacket and muddy hands in the port Queen Anne’s Battery she holds one of those bags. “This biodegradable plastic bag has been in the ocean for six years!” And as a continuation, in a small thread, she added: “It is important to discuss the credibility of products to ensure that they benefit the environment. Do you think it will be gone in the next six years?

When we talk to her, she tells with amusement that these bags have accompanied her throughout her career. But then her tone is more serious given the dimension of the problem. First of all, there is no common definition of what the term ‘biodegradable’ means. And it emphasizes that a product named like that only decomposes according to the material with which it is made and under very specific conditions. “For example, a very high temperature, which can only be obtained in an industrial plant. What we try is that the industry and consumers understand the same thing by biodegradable, that everyone is on the same page”, she comments.

But this common and regulated definition does not exist at the moment, beyond the certification systems, which do not imply a legal obligation, they are voluntary. The group of independent scientists that make up the Sapea organization and that advises the European Commission, published in 2021 a macro report on the impact of biodegradable plastics in which he offered a definition: “It is the microbial transformation of all its organic components into carbon dioxide, new microbial biomass and mineral salts under oxic conditions; or in carbon dioxide, methane, new microbial biomass and mineral salts under anoxic conditions”.

Raquel Iglesias is the director of the small Madrid company Dríade SM, which in 2019 – the same year in which the researcher Imogen Napper took her bag out of the ocean for the first time – presented a new methodology to rigorously measure how much can be recycled from a container. For her, the most important messages about biodegradable plastics are two: “They cannot be thrown into nature, because very specific conditions must be met for that plastic to disintegrate; On the other hand, the key is time. Conventional plastic also disappears, but in how long, in 300 years?

For this technique there is a great deal of confusion about the term and what to do with packaging labeled ‘biodegradable’. For example, throwing them in the yellow container is useless, it’s even worse: “They contaminate the recycling process,” explains Iglesias. And regarding ‘compostable’ materials, the brand should explain very well that they only decompose in very specific temperature and oxygen conditions, certainly not in the middle of the field or on a beach. As Imogen Napper summarizes: “There are solutions for biodegradable plastic only if it ends up in the right container.”