The latest research urges scientists to thoroughly test materials proposed as plastic substitutes before they see widespread use in consumer products. A recent study reveals that bio-based materials, intended to replace conventional plastics, might pose significant health risks to essential species on Earth.

Bio-based materials are being promoted as eco-friendly plastic alternatives, increasingly incorporated into textiles and everyday items like clothing, wet wipes, and period products. However, microfibers from these materials are released into the environment during laundry, through sewage sludge used as fertilizer, and from the regular wear and tear of products.

Despite the global increase in bio-based product production and sales, limited research exists to understand their potential environmental impact. To address this, a study published in Environmental Science and Technology examined the effects of conventional polyester and two bio-based fibers—viscose and lyocell—on earthworms, which are crucial for healthy soils worldwide.

The research revealed that in high concentrations, 30% of earthworms exposed to polyester fibers died after 72 hours. However, mortality rates were even higher for earthworms exposed to bio-based fibers: up to 60% for lyocell and 80% for viscose.

Long-Term Impacts on Earthworm Health and Behavior

In a second experiment involving lower, environmentally relevant fiber concentrations, earthworms in viscose-containing soil exhibited reduced reproduction compared to those in polyester. Meanwhile, those in lyocell-treated soils showed stunted growth and burrowed more than earthworms in soils containing other fibers.

The study underscores the complexity of reducing microplastic pollution globally and highlights the need for rigorous testing of plastic alternatives before their market release. The BIO-PLASTIC-RISK project, conducted by researchers from the University of Plymouth and the University of Bath, spearheaded this study with £2.6 million funding from the Natural Environmental Research Council.

Need for Further Research and Oversight

Dr. Winnie Courtene-Jones, the lead author of the study and a Lecturer in Marine Pollution at Bangor University, noted, “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.”

This study builds on earlier 2024 research that found biodegradable materials in teabags can increase earthworm mortality by up to 15% and hinder reproduction. Its release coincides with the upcoming United Nations summit in Busan, South Korea, where world leaders will discuss 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 these discussions with global policymakers and scientists. He stated, “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. 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.”