Natural replacements for plastics may pose greater risks

Recent research suggests that some natural replacements for plastic can be more detrimental to nature than plastics themselves. Scientists from the University of Plymouth have demonstrated that cellulose fibers present in the soil cause higher mortality in earthworms than polyester fibers.

In experiments conducted on earthworms, the impact of small fibers released into the environment from both plastic and biologically made items was studied. At high concentrations of polyester fibers, 30% of the earthworms died after 72 hours.

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

This research highlights the complexity of the plastic pollution problem and underscores the need for thorough testing of new materials promoted as eco-friendly alternatives. Dr. Winnie Courtene-Jones, the lead author of the publication in the journal "Environmental Science & Technology," points out that in 2022, more than 320,000 short tons of biodegradable and bio-based fibers were produced worldwide.

"The research shows that a significant portion of them will end up in the environment. Our study found that bio-based fibers have a range of negative impacts on earthworms—animals crucial to ecosystem functioning," comments Courtene-Jones.

The new publication appeared shortly before the meeting of world leaders in Busan, South Korea, where the last round of negotiations regarding a possible global plastic treaty will take place. Professor Richard Thompson, one of the study's main authors and head of the International Marine Litter Research Unit at the University of Plymouth, will participate in these discussions.

He points out that besides recycling and reuse, combating plastic pollution requires reducing the amount of plastic used and produced. Although there is increasing demand for alternatives to plastics, the latest research shows that these alternatives must be thoroughly examined to understand the consequences of their widespread use.

"I deeply believe that the plastic pollution crisis can be solved, but independent scientific evidence will be crucial in avoiding unintended consequences as we seek new solutions," says Professor Richard Thompson.

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