When trying to make more sustainable clothing choices, many consumers follow a simple rule: choose natural fibres over synthetic ones. Cotton instead of polyester. Wool instead of acrylic. Linen instead of nylon.
The logic seems straightforward. Natural fibres originate from plants or animals, while synthetic fibres are largely derived from fossil fuels. If a fibre comes from nature, it must surely be the more environmentally friendly option.
But our new review of research examining textile chemistry, fibre type and environmental consequences suggests the reality is far more complicated.
What matters is not simply where a fibre comes from, but what happens to it throughout its journey from the raw material to a finished garment. Many consumers imagine a cotton T-shirt as little more than processed plant material. Yet cotton is a water-intensive crop and, in many parts of the world, relies heavily on pesticides and fertilisers. Even after harvesting, the story doesn’t end. Before reaching the shop floor, textiles often undergo extensive chemical processing.
Fibres may be bleached, dyed, softened, strengthened or waterproofed. Some are treated to make them flame retardant or resistant to creasing, staining and microbial growth. These treatments help create the products consumers have come to expect, improving appearance, durability and performance. But they also influence how textiles behave throughout their life cycle. This affects how they degrade, what they release into the environment and how easily they can be recycled.
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More than fibre type
Certifications for sustainable textiles often focus on the environmental consequences of sourcing the raw fibre itself. Cotton requires land and water. Polyester relies on fossil resources. Wool raises questions about livestock emissions and land use. These are important considerations, but they tell only part of the story.
In collaboration with colleagues at the sustainable textiles and apparel research group at the University of Manchester, we have published a systematic review that highlights how a garment’s environmental cost depends not only on the fibre itself – but also on the chemicals used throughout production and the ways in which those materials behave during use, reuse and disposal.
Our latest research shows that chemicals introduced during cultivation, fibre production, dyeing, finishing and performance enhancement can affect how textiles behave in the environment, including how they degrade, what they release and how easily they can be recycled.
For example, per- and polyfluoroalkyl substances (Pfas), often referred to as “forever chemicals”, are used to give textiles water- and stain-resistant properties but are highly persistent in the environment. Formaldehyde-based finishes improve crease resistance.
Other chemicals, including some phthalates (used to make some coatings and plastics more flexible), bisphenols (used in some plastic and textile coating manufacture), heavy metals and dye compounds, have also been associated with environmental or human health concerns depending on how they are used and managed throughout a product’s life cycle.
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This complexity is often invisible to consumers. Two garments made from the same fibre may have very different environmental footprints depending on how they were processed and finished.
Public and policy discussions about textile pollution have largely focused on synthetic microplastics. Yet our review of the evidence suggests the picture is more complex. Natural fibres such as cotton and wool, together with regenerated cellulose fibres such as viscose and lyocell (derived from wood pulp), have also been widely detected in rivers, oceans and rain or cloud particles.
This does not mean natural fibres are necessarily more harmful than synthetic alternatives. Rather, it highlights that pollution cannot be understood simply by looking at fibre origin.
As textiles are worn, washed and eventually discarded, both fibres and the chemicals applied to them can be released into the environment. They may enter rivers and oceans through wastewater, accumulate in soils through the application of sewage sludge, or become airborne as dust and fibre fragments. Understanding how fibres and the chemicals they carry move through the environment is now an active area of research for scientists around the world and one that is reshaping how we think about the true environmental footprint of our clothes.
The challenge for recycling
Chemical complexity makes it harder to create a more circular textile system – one that aims to design out waste by keeping materials in use through reuse, repair and recycling. Complex mixtures of fibres, dyes and chemical finishes make it more difficult to sort, recycle and recover textiles into high-quality new products.
As governments and industry invest in more circular textile systems, understanding the chemical history of textiles is becoming increasingly important. A recycled cotton fibre, for example, may still carry dyes, finishes or performance treatments that affect how it can be safely reused or recycled. Yet this information is often incomplete or unavailable, making it difficult for recyclers, manufacturers and retailers to know exactly what materials they are handling.
This is one reason why policymakers are introducing measures such as digital product passports. Although textile specifc requirements are still being developed, these passports will store information about a product’s materials, repairability and environmental characteristics throughout its life cycle. Alongside greater transparency about the chemicals used in textile production, initiatives that enable greater transparency can support safer recycling, reduce waste and help create a more circular textile industry.
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Beyond natural v synthetic
Our findings do not suggest that consumers should avoid natural fibres. Nor do they suggest that synthetic fibres are the answer.
There is no perfect fibre.
Researchers in Finland have argued the need to move beyond simplistic sustainability narratives. Consumers can make more informed choices by buying fewer, higher-quality garments. They can use products for a longer time, repair and reuse clothing where possible, and support brands that are transparent about the materials and chemicals they use.
Certification schemes such as Oeko-Tex (which means the fabric has been tested for harmful substances and found to be below specific levels) or bluesign (which means the textile has been manufactured using responsible chemical management and environmental practices) can also provide useful reassurance.
The most sustainable textile is not necessarily the one made from a natural fibre. It is the one designed, manufactured, used and managed responsibly throughout its entire life cycle.
To build a genuinely sustainable textile industry, we need to stop asking whether a fibre is natural or synthetic and start asking what has happened to it along the way … and where it will end up.
Jane Wood receives funding from UKRI Innovate UK.
Charlotte Barras receives funding from UKRI Innovate UK.
Elena Probert receives funding from UKRI Engineering and Physical Sciences Research Council.