Reviewed by Lexie CornerNov 6 2024
A recent study published in Environmental Science and Technology by researchers at the University of Plymouth examined the impact of traditional polyester fibers and two bio-based fibers—viscose and lyocell—on earthworms, which play an essential role in maintaining soil health worldwide. The study revealed that bio-based materials might pose a greater risk to some of the planet's key species compared to the conventional plastics they are intended to replace.
Image Credit: Lloyd Russell
These materials are promoted as eco-friendly alternatives to plastics and are commonly used in textiles and products such as clothing, wet wipes, and period products.
However, microfibers from these materials enter the environment through various processes, including laundering, the use of sewage sludge as fertilizer, and the general wear and tear of textiles.
While the production and sale of bio-based products are increasing globally, there is limited research on their potential effects on species and ecosystems.
The results indicated that at high fiber concentrations, 30 % of earthworms exposed to polyester died within 72 hours. In contrast, mortality rates were significantly higher for earthworms exposed to bio-based fibers, with up to 60 % dying from lyocell exposure and 80 % from viscose exposure.
In a second experiment using environmentally relevant fiber concentrations, earthworms in soils containing viscose fibers showed decreased reproduction compared to those in soils with polyester fibers. Additionally, earthworms exposed to lyocell fibers displayed reduced growth and increased burrowing activity within the soil compared to those exposed to the other fiber types.
According to the researchers, these findings underscore the complexity of global efforts to mitigate microplastic pollution and emphasize the need for thorough assessments of new materials proposed as plastic alternatives before their market release.
This study was conducted under the BIO-PLASTIC-RISK project, led by teams from the University of Plymouth and the University of Bath, with £2.6 million in funding from the Natural Environment Research Council.
Over 320,000 tonnes of bio-based and biodegradable fibers were produced globally in 2022, and research shows that substantial quantities of that will end up in the environment. However, evidence of their ecological impacts has been lacking. Our study has shown that bio-based fibers 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.
Dr. Winnie Courtene-Jones, Study Lead Author, University of Plymouth
This new study builds on research published earlier in 2024, which found that exposure to materials from biodegradable teabags can lead to a 15 % increase in earthworm mortality and negatively impact their reproduction.
The findings come just before world leaders gather in Busan, South Korea, for the final round of negotiations on a potential Global Plastics Treaty. Professor Richard Thompson OBE FRS, senior author of the study and Head of the University of Plymouth’s International Marine Litter Research Unit, will join policymakers, scientists, and other global delegates at these discussions.
It is clear that along with recycling and re-use, tackling plastic pollution will require a reduction in the quantities of plastics used and produced. There is increasing interest in alternative materials that could be used as substitutes for plastic, but this publication further emphasizes the importance of testing new innovations in relevant environmental settings prior to widescale adoption.
Richard Thompson OBE FRS, Head, International Marine Litter Research Unit
Richard Thompson adds, “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.”
Journal Reference:
Courtene-Jones, W., et al. (2024) Are Biobased Microfibers Less Harmful than Conventional Plastic Microfibers: Evidence from Earthworms. Environmental Science & Technology. doi.org/10.1021/acs.est.4c05856.