Natural plastic alternatives: Environmental impact revealed

Recent research indicates that natural substitutes for plastic can be more damaging to the environment than the plastics they aim to replace. Scientists at the University of Plymouth have shown that cellulose fibres in the soil lead to higher mortality rates in earthworms than polyester fibres.

In experiments on earthworms, the effects of small fibres released into the environment from both plastic and bio-based items were investigated. At high concentrations of polyester fibres, 30% of the earthworms died after 72 hours.

In contrast, the presence of cellulose-based fibres—lyocell and viscose—resulted in mortality rates rising to 60% and 80%, respectively. The study also reveals that viscose significantly reduced the reproductive abilities of earthworms compared to polyester. Earthworms placed in soil containing lyocell fibres exhibited reduced growth and behavioural changes, such as increased tunnel digging speeds compared to exposure to other fibre types.

The research underscores the complexity of the plastic pollution problem and highlights the necessity of thoroughly assessing new materials promoted as eco-friendly alternatives. Dr. Winnie Courtene-Jones, the lead author of the study published in the journal "Environmental Science & Technology," notes that in 2022, more than 290,000 metric tonnes of biodegradable and bio-based fibres were produced worldwide.

"Our study has shown that bio-based fibres have a range of adverse effects on earthworms – animals which are critical to the functioning of the environment. It highlights the importance of gathering further evidence before alternatives to conventional plastics are made available even more widely," comments Courtene-Jones.

This new publication was released just before the meeting of world leaders in Busan, South Korea, where the latest round of negotiations regarding a proposed global plastic treaty will occur. Professor Richard Thompson, one of the primary authors of the study and head of the International Marine Litter Research Unit at the University of Plymouth, will participate in these discussions.

He emphasises that, alongside recycling and reuse, tackling plastic pollution requires reducing the quantity of plastic used and produced. Although there is increasing demand for alternatives to plastics, the latest research underscores the need for thorough examination to understand the consequences of their widespread use.

"I firmly believe it is possible to tackle the plastic pollution crisis, but independent scientific evidence will be critical in helping us avoid unintended consequences as we look for solutions," says Professor Richard Thompson.

Previous studies, published earlier this year, demonstrated that exposure to materials used in biodegradable tea bags can increase earthworm population mortality by up to 15% and negatively affect their reproduction.