A recent study by British academics on the toxicity of biobased fibers may overturn the original perception of “biobased” proponents. The authors suggest that bio-based fibers (viscose and lyocell) may be more harmful to earthworms and more harmful to the environment than petrochemical-based fibers (polyester). This bio-based fiber toxicity theory certainly puts bio-based fibers in jeopardy, but in reality the study has major flaws and the one-sided findings will not hinder the process of replacing bio-based materials.
1、Bio-based materials, an environmental star with high expectations
Bio-based materials have long been touted as environmentally friendly alternatives to traditional plastics, reducing oil and coal extraction, and the future looks bright. The Global Organization for Economic Cooperation and Development (OECD) optimistically predicts that at least 20% of the world's petrochemicals will be replaced by bio-based products by 2030. The European Union's Industrial Biotechnology Vision predicts that by 2030 biobased feedstocks will replace 6%-12% of chemical raw materials, and that 30%-60% of fine chemicals will be made from biobased sources. The United States “Biomass Technology Roadmap” plans that bio-based chemicals will replace 25% of organic chemicals and 20% of petroleum fuels in 2030.
2、Bio-based fibers, the mystery of the death of earthworms
However, a recent UK study on bio-based materials has come to rather bombastic conclusions.2024 The study, “Are bio-based microfibers less harmful than traditional plastic microfibers: evidence from earthworms,” published November 5, 2024, by academics at the Universities of Plymouth and Bangor in the UK, in Environmental Science and Technology, states that, in controlled environments, bio-based fibers appear to have a lethal Effects.
In this study, the researchers compared bio-based microfibers (i.e., viscose fibers and lyocell fibers) found in wipes, menstrual products, and clothing to polyester fibers used in similar applications.
The results of the study showed that under high concentration conditions, earthworms suffered up to as much as 80% mortality when exposed to viscose fibers, and 60% mortality when exposed to Lycopersicon. In contrast, earthworm mortality in polyester-contaminated soil was only 30%.
In another test, earthworms were placed in different soils containing different concentrations of various types of fibers. The earthworms in the viscose-contaminated soil had a reduced ability to reproduce compared to the earthworms in the polyester-contaminated soil. In the Lycell-contaminated soil, earthworms were inhibited in their growth and burrowed more deeply into the soil.
These results seem to indicate that the bio-based fibers are seriously interfering with the survival and normal physiological functioning of earthworms, which is quite different from our previous perception of bio-based materials as environmentally friendly, and puts a mysterious and dangerous veil over the bio-based fibers.
It is important to note that the paper uses Lycell fibers supplied by Lenzing Austria, which do not contain chemical additives. Therefore the toxicity is most likely due to the particles and their physical properties rather than the accompanying chemicals.
3. Major flaws in British academic research, ignoring long-term ecological impacts
However, dissecting this study closely, it is easy to see that there are significant flaws.
There may be a biased understanding of bio-based microfibers in the paper. Bio-based microfibers usually have better degradability, are mostly sourced from natural biomass, and are more easily broken down into harmless small molecules in the natural environment. They have a shorter residual cycle under natural conditions than conventional plastic microfibers. Although earthworms may be observed to react to bio-based microfibers in the short term, in the long term, this degradability will significantly reduce their cumulative harm to the environment. Instead, the paper may not have adequately considered the environmentally friendly properties of bio-based microfibers throughout their life cycle, focusing only on immediate phenomena in earthworm experiments, and thus incorrectly comparing their level of harm to that of traditional plastic microfibers.
The paper also ignores long-term ecological effects. In terms of long-term stability of the ecosystem, traditional plastic microfibers will persist in the environment and may continue to be enriched as they pass through the food chain due to their difficult-to-degrade nature. This long-term, potential harm is not adequately assessed in the paper. Although the results presented in the short-term earthworm experiment may appear to be harmful to bio-based microfibers, they are not comparable to the serious long-term consequences of traditional plastic microfibers, such as damage to soil structure and reduced biodiversity. Focusing only on the short-term earthworm data and ignoring the long-term ecological effects is a major flaw in the paper's conclusions, and this one-sided view can mislead people about the true harm of both types of microfibers.
4. Bio-based fiber toxicity theory, affecting the progress of bio-based substitution?
A few weeks after the publication of the paper, on November 25-December 1, the United Nations convened world leaders in Busan, South Korea, for a final round of negotiations (INC-5) on a possible global plastics treaty, with the goal of creating a legally binding international instrument on plastic pollution (including in the marine environment) (a global “Plastic Limit Order “).
Richard Thompson, author of the paper, Director of the International Marine Litter Research Unit at the University of Plymouth, and Fellow of the Royal Society, will also be involved in the development of the agreement.According to Thompson, “As well as recycling and reuse, tackling plastic pollution will require reductions in the amount of plastics used and produced. There is growing interest in materials that can replace plastics, but this study further emphasizes the need to test new materials in relevant environments before large-scale application.”
In previous negotiations, the European Union, Canada, South Korea and other countries have advocated a reduction in the production of new plastics, with the use of biobased alternatives to petroleum-based ones becoming a clear trend. However, the emergence of the “toxicity of bio-based fibers” argument has complicated the process of replacing traditional materials with bio-based alternatives. Will it hinder the development of bio-based substitution? This is certainly an urgent question that needs to be addressed, and we need to explore the real environmental impacts of bio-based fibers in a more comprehensive and in-depth manner, rather than being swayed by one-sided research conclusions.
