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Eco-friendly or eco-threat? The environmental risks of natural and semi-synthetic fibers
12 August 2025
A new publication co-authored by two PML PhD Researchers, Charlotte Woodhouse and Hayley McIlwraith, calls for a re-evaluation of how we view “natural” and semi-synthetic fibres as alternatives to synthetic microplastics, warning that these materials may still pose environmental risks.
Image caption: Cotton bolls; round, fluffy clumps in which cotton forms and grows on a cotton plant. Cotton is a widely used natural fibre, and while it’s often seen as a more eco-friendly alternative to synthetic fibres, its environmental impact is quite complex.
Published in Environmental Research Communications, the open-access paper is the result of collaboration between early-career researchers who took part in a dedicated microplastics conference last year. The event, hosted by Dr Dannielle Green of Anglia Ruskin University, brought together scientists to explore pressing issues in microplastics research and identify gaps that need addressing.
Dr Green said:
“Our previous research has shown that plastics and microplastics labelled as “biodegradable,” “compostable,” “biobased,” or “natural” can cause environmental harm comparable to conventional microplastics. However, there remains a significant knowledge gap concerning fibres made from “natural” or “semi-synthetic” materials. It was a privilege to collaborate with such a skilled and motivated group of early career researchers, and I look forward to seeing the valuable contributions they will make in advancing this important field.”
Led by Daniel Jolly of the University of East Anglia (UEA), the letter challenges the common assumption that materials such as cotton, rayon, or viscose are environmentally benign alternatives to synthetic microfibres. The authors highlight a growing body of evidence that even non-synthetic fibres can persist in the environment and contribute to ecological harm – especially when treated with dyes, chemicals or subjected to industrial processing.
‘The ecotoxicological consequences of ‘natural’ and ‘semi-synthetic’ textile fibres have not been extensively investigated, with only a handful of studies exploring their impact on biota. Ingestion of fibres has been demonstrated to influence the development of juvenile invertebrates exposed to cotton microfibres, and ingestion of rayon microfibres increased oxidative stress, altered the gut microbiome and reduced enzyme activity within mussels demonstrated that the morphology of wool and cotton, combined with the chemical additives associated with them, triggered oxidative stress and perturbed digestive function in oysters (Crassostrea gigas), higher than those exposed to synthetic fibres. This could stem from the more rapid degradation of natural and semi-synthetic fibres compared to synthetics, then release additives at a higher concentration over a shorter timescale.
To date, the physical effects of fibre morphology and the chemical effects associated with their additives have not been fully researched. It is also unclear as to how the presence and degradation of natural and semi-synthetic fibres may contribute to the occurrence, persistence and bioavailability of chemical additives in the environment. Future research should focus on quantifying and characterising the effects of natural and semi-synthetic textile fibres and their associated additives on the overall health and functioning of organisms, as well as how additives may influence the breakdown of these fibres and their persistence.’ [Extract from paper]
Image: Electron micrograph of common microfibres: a) Synthetic PET, b/d) semi-synthetic rayon/ lyocell (regenerated cellulose), c) cotton. Due to the small size of microfibres, identification using spectroscopic or visual techniques can lead to misidentification or missed observations.
Co-author Hayley McIlwraith – PhD researcher at PML and UEA – said:
“This paper emerged from incredibly productive conversations during the conference. It’s exciting to be part of a publication that highlights how we, as early-career researchers, can collectively raise awareness about overlooked environmental threats and help steer the direction of future microplastics research.”
Co-author Charlotte Woodhouse – PhD researcher at PML and the University of Exeter – added:
“It’s often assumed that natural or semi-synthetic fibres would be harmless in the environment, but our research highlights the need for more nuanced thinking. Contributing to this paper has been a fantastic opportunity to question assumptions and help shape a more holistic approach to the many forms of pollution.”
Lead author, Daniel Jolly of UEA said:
“Although conventional microplastics have been extensively covered in the last decade, only a handful of studies have considered the potential for other non-plastic microparticles to be harmful. Our research on these investigations highlighted the lack of knowledge and transparency in what our everyday products actually contain. In some cases, non-plastic microfibres have caused similar or even greater sub-lethal effects on organisms such as oyster, mussel and shrimp species. This topic desperately needs further research effort so that we can make sure our sustainable choices really are sustainable. Collaboration and communication are at the heart of impactful research and it has been a fantastic opportunity to work with other researchers on this paper.”
The letter concludes with a call for a more comprehensive environmental risk assessment of all fibrous pollutants – not just synthetic plastics – and encourages the research community to broaden the scope of microplastics monitoring, policy and mitigation strategies.
