While regulators focus on trying to count fibers, there’s a solution hiding in plain sight.

Polyester, acrylic, nylon – no matter what you call it, synthetic textiles are plastic products. This means that like all other plastic products, during their production, use and when they become waste and are mismanaged, they persist in the environment and fragment into smaller plastic pieces, including microplastics.

Over time and across the globe, these small particles accumulate into staggering amounts. A 2024 study published in Nature Communications estimates that the global apparel sector generated approximately 21 million tonnes of plastic waste in 2019. Of that, around 8.3 million tonnes leaked into the environment. This is nearly one-and-a-half times the mass of the Great Pyramid, and approximately twice the annual global production of all natural fibers combined – in just one year.

Where the leakage actually comes from

The dominant driver of that leakage, however, is not what most people assume. According to the aforementioned study, mismanaged synthetic clothing at end of life – including exports to secondary markets with poor waste management infrastructure – accounts for an estimated 6.6 million tonnes per year, or 88 percent of plastic leakage from the synthetic apparel value chain. By contrast, microfiber releases during fiber production and garment washing represent less than 1.5 percent of total plastic leakage from the global apparel industry by mass – approximately 0.11 million tonnes per year.

Even if the sector were to stop using synthetic materials today, tens of millions of tonnes of existing synthetic clothing waste would remain as an ongoing source of plastic fragments. And the environmental impacts do not end there. Other research also indicates that common plastics can emit greenhouse gases methane and ethylene during degradation under sunlight exposure, adding a further climate dimension to the problem.

Despite this evidence, the current policy debate has become heavily concentrated on the technical challenge of measuring microfibers and microplastics at a microscale. That focus obscures the underlying issue: the continued growth in plastic textile use and the leakage of synthetic clothing waste into the environment on a truly macro scale.

The absence of a perfect measurement methodology has, in practice, become grounds for delaying action on drivers that are already well understood.

What effective policy looks like

Addressing synthetic textile pollution need not, however, require resolving every measurement question first. A more direct approach is available: regulating based on the volume of plastic fibers placed on the market, and ensuring safe end-of-life routes for synthetic garments.

Two principles can be drawn from the evidence. First, the policy objective – reducing persistent plastic pollution – is being diluted by a broader framing around textile fragmentation generally. All textiles shed fibers, but only fossil-based synthetic polymers persist as plastic pollution. Second, policy and consumer communication that explicitly distinguishes between plastic microfibers and non-plastic fibers such as wool, cotton and bast fibers reflects the fundamentally different environmental persistence of each.

On that latter point, a straightforward model for consumer-facing labeling already exists. All that would be needed in this case is short and factual information, such as: “Contains synthetic (plastic) fibers. When released to the environment, plastic fibers persist and can become microplastics. Follow care and end-of-life instructions.”

A note on machine-washable wool

One area where misinformation has complicated the picture is machine-washable wool. Here, a common claim holds that wool treated for machine washability has been “plastified” – rendered equivalent to a synthetic fiber. The science does not support this.

Machine-washable wool uses a small amount of Hercosett resin, typically around 1–2% of the fiber weight, which bonds to the fiber surface during processing. Research into wool biodegradation has detected no microplastic formation from Hercosett-treated wool. The resin biodegrades alongside the wool fiber rather than persisting as plastic pollution. Some studies have even found that treated wool biodegrades faster than untreated wool.

Microplastics form when solid plastic materials physically fragment. That requires a solid plastic layer, which machine-washable wool does not have. When wool biodegrades – in water or soil – it is consumed by bacteria and fungi, leaving no detectable trace within months depending on conditions. This is fundamentally different behavior from polyester or nylon, both of which are known to break down into non-biodegradable microplastics.

The classification of Hercosett resin as a plastic is scientifically accurate. Its behavior in the environment, however, is not remotely in the same class as synthetic textiles.

Getting the policy right

Policy for the apparel sector that addresses both the volume of synthetic textiles placed on the market and the waste pathways is needed to stem the growing crisis of microplastic pollution. The science on this is available. The question is whether incoming policy will reflect it.

Photos: Woolmark