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Sophie Benson
In their quest to appear more sustainable, fashion brands began to seek out the lowest impact fabrics — and it just so happened they weren’t cotton, wool, or silk, but the plastics they were already using. It was illogical and, as it turns out, categorically untrue. But a leading materials scoring system perpetuated the myth for years, with damaging results, and it’s important we unpick how and why it happened.
The fashion industry is a sprawling, global entity, which crosses paths with a multitude of other industries, from oil extraction to agriculture. Accurately measuring its impact is incredibly difficult, so when a seemingly feasible stat or fact emerges, both the industry and the press run with it. “Fashion is the second most polluting industry after oil” is still used by brands and fashion organisations today, despite being thoroughly debunked. As are fibre-related facts including “cotton consumes a quarter of all pesticides” and “it takes 20,000 litres to make a t-shirt”. Cotton has been a particular target of misinformation, laying the foundations for the turning tide against natural fibres.
There is no known primary source for the latter claim, and using one number to represent a global industry spanning different climates, rainfall levels, and agricultural techniques is misleading at best and irresponsible at worst. In the US, cotton farmers in the Southeast use 234 litres of irrigated water per kilogram of cotton on average, whereas in the West that figure is 3,272 litres. This illustrates the huge contrasts even within the borders of a single country, and the need for greater care to be taken in reporting and information-sharing.
The specifics of language are also important. Cotton has, for years, been characterised as “thirsty”, supposedly endangering the communities who live in the dry regions in which it grows. But cotton doesn’t ‘use up’ water, it absorbs it as part of the natural water cycle which sees it then evaporate from the soil and become rain. ‘Vegan leather’ has been widely adopted by brands as a misleading replacement for plastic, and synthetic fabrics are deemed ‘cruelty-free’ without consideration of any social and environmental impacts they have, such as water supply pollution or wildfires caused by using fossil fuels.
Natural fibres aren’t perfect. We know certain pesticides used by certain cotton farmers have been harmful to health, we know chromium leather tanning can be incredibly polluting, and we know irresponsible grazing management can exacerbate soil erosion. But using handpicked examples — without context or proper research — to demonise all natural fibres is a dangerous approach, legitimising the fashion industry’s use of fossil fuels in the face of a climate crisis.
The Higg Index, a rating system for value chains, was introduced in 2011 by the Sustainable Apparel Coalition (SAC). Used by over 21,000 organisations, it is posited as the “leading environmental and social assessment in the apparel industry”. There are five tools which comprise the Higg Index, but it was the Materials Sustainability Index (MSI) which brands relied heavily on in their decision-making regarding fibres and fabrics. MSI scores represent the impact of producing one kilogram of the material in question, with a score of 10 representing an “average impact”. It’s worth diving into a selection of the scores:
Elastane/spandex fabric – 27.26
Polyester fabric – 36.2
Acrylic fabric – 48.62
Nylon – 48.8
Wool – 80.6
Cotton fabric – 101
Alpaca – 316
Silk – 1,076
The Higg MSI heavily favours fossil fuel-based, synthetic fabrics, presenting polyester and elastane as environmentally responsible choices over natural fibres like cotton, doubling down on existing untruths. Using Higg logic, natural silk is 29 times worse for the planet than synthetic polyester. With the birth of the Higg MSI, the industry was given the green light to continue using polyester, already the most widely used fibre in the world, despite the reliance on fossil fuels and the pollution caused by microplastic shedding.
Ignoring doubts voiced by many other industry bodies over the accuracy of the scoring system, the Higg Index remained the leading metric by which to measure material impact until mid-2022, when it was publicly criticised by both the New York Times and the Norwegian Consumer Authority. The latter encouraged the SAC to improve the underlying data, its claims, and the presentation of its index to avoid greenwashing. As a result, the SAC “made the decision to pause the consumer facing transparency program globally… removing the Higg Index seal and scorecard from the participating online retail platforms”. But the Higg Index remains live, as do the scores.
The Higg Index didn’t come into being spontaneously, and it wasn’t solely the work of the SAC. In 2009, Walmart and Patagonia invited CEOs of leading global companies to collaboratively develop an index to measure the environmental impact of their products. In 2012, Nike donated its own internal Materials Sustainability Index to the SAC, which would become the Higg MSI.
Nike’s MSI had some significant knowledge gaps. For instance, where certain data wasn’t available Nike made “estimates based on [its] professional experience and judgement”, or used analogous data such as chicken LCAs for goose down. As we explored in Mythbusting: LCAs are reliable comparative analyses, flawed data inputs can have huge repercussions in terms of the reliability of the information they produce, and the very index the Higg MSI scores were initially built upon was not sound.
Also explored in our LCA mythbusting piece was the use of inaccurate, outdated, favourably weighted data from plastics manufacturing associations to calculate the Higg score for polyester. Meanwhile, its ‘water scarcity’ score for cotton is a whopping 57.3, perpetuating the myths unearthed above. It makes perfect sense that plastics manufacturers would want brands to flock to plastic fibres, and it also makes sense that brands like Nike, Patagonia, and Walmart — which rely heavily on polyester — would want to continue doing so without it affecting their standing as sustainable leaders.
The SAC boasts over 280 members and the listed benefits of joining include “[enhancing] your company’s reputation” and “[shaping] the evolution of the Higg Index”. On the list of brands you’ll find Arc’teryx, Asos, Boohoo, Crocs, Gymshark, H&M, Inditex, Lululemon, Mango, Primark, Puma, Rapha, Underarmour, and Urban Outfitters. From premium outdoor apparel to cheap fast fashion, the members are major synthetics users. It bears out that they would want to pay up to USD 90,000 in yearly dues to uphold the perception that the cheap, synthetic fibres they’re already accustomed to using are the way forward for a sustainable future.
When faced with data about factors such as water usage or pollution levels, check for context. What region or climate does it refer to? Are such details even disclosed? If not, ask why. You should also check for sources. If a source links through to a report which links to an article which links to another report with seemingly no primary source, it’s time to question the veracity of the claim.
Just as tobacco companies used to fund studies which ‘proved’ the health benefits of smoking, synthetics-using fashion brands will fund – or contribute data to — research and rankings which make natural fibres look like the worst possible option. Third-party analysis is a must.
The continued use of virgin plastic fibres like polyester mean the continued extraction of fossil fuels. For even a 50% chance of staying on a 1.5 degree pathway, 90% of coal and 60% of oil and gas must stay in the ground. Demonising natural fibres and promoting the use of synthetics compromises this goal.