Why our shoes need to disappear
· 8 min read
The footwear industry’s reliance on plastics began after World War II. The introduction of synthetic rubber, EVA, PVC, and high-performance PU revolutionized shoe design. These materials were cheaper, lighter, and more versatile, enabling the comfort and durability we now take for granted. But the very innovative chemistry once considered revolutionary is now our greatest environmental liability. These synthetic plastics were engineered to resist nature, ensuring performance during use but prolonged existence, their persistence long after.
The modern shoe is a complex product of plastics designed for human performance. But when you hold up a brand-new shoe, you are also holding centuries of environmental pollution and damage to human health. Virtually every component, from the cushioned midsole, exchangeable insoles, the rigid heel counter, to the durable outsole, is a forever plastic with lifespans of centuries, yet designed for a product lifecycle of mere months.
This dissonance between design intent and environmental fate defines the footwear industry, an economy that produces over 20 billion pairs annually1,2. For decades, the narrative of sustainability was one of compromise; we accepted the inevitable landfill or pollution of billions of pairs of shoes each year as a necessary cost for comfort, durability, and accessibility.
As new research emerges, the scale of this cost is far greater than we once imagined. Plastic pollution is not limited to the plastic water bottles or take-out containers we see littering our streets. While those represent macro-pollution, a far more pervasive threat comes from micro-pollution, tiny fragments of plastics called micro-and nano-plastics, often smaller than five millimeters and sometimes invisible to the naked eye. For discarded plastics, including footwear, these microplastics are generated when heat, rain, sunlight, weathering, and other natural abrasion processes fracture the plastics into smaller and smaller pieces, becoming persistent microplastics that migrate through our oceans, soils, and even the air we breathe. For footwear, the environmental cost of microplastics has an additional contributor: the 20 billion pairs of shoes produced each year don’t just end up as landfill waste, macroplastic pollution, and their eventual microplastic pollution; they also continuously shed hundreds of thousands of microplastic particles as the soles wear down just from scuffing against the ground when walking or running. If each shoe were to lose just 1% of its mass per year from wear, global footwear would release 100,000 tons of microplastics per year. Worse with every step we take, we are releasing these microplastics where we live, we work, where we play, and where we raise our families, with direct impacts on our health.
Research confirms that microplastics are ubiquitous pollutants capable of crossing biological barriers and posing serious health concerns 3, 4, 5. Research into plastic pollution dates back to 19696, but the field is still nascent. The word “microplastic” wasn’t even coined until 2004 by Prof. Richard Thompson. Yet in just the last five years, scientists have found microplastics accumulated in nearly every organ of the human body, including the liver, placenta, bloodstream, and brain, and have already linked these particles to cardiovascular disease, inflammation, and neurodegenerative diseases3, 4, 7, 8, 9. Based on these reports, an understanding of microplastics as a global health care crisis is emerging, and the local contribution from footwear to this crisis is alarming.
But what if this environmental cost wasn’t inevitable? What if the highest-performing materials could also be designed to safely disappear back into nature? To get there, we must first understand how this persistence was engineered, why incremental fixes have failed, and how a new materials revolution is finally allowing us to design the first truly biodegradable, environmentally responsible shoe.
Over the years, the footwear industry has attempted to address its plastic problem through end-of-life initiatives like recycling, downcycling, and take-back programs, but these efforts have largely failed to create meaningful impact. Recycling infrastructure for shoes is almost nonexistent — less than 5% of global footwear is ever recycled. A single pair of shoes can contain more than 10 different materials bonded with adhesives, making separation and processing nearly impossible. Even when collected, most shoes are downcycled into low-value products like playground flooring or carpet padding, which are temporary detours that still end in landfills. Large-scale “circularity” pilots by major brands have also struggled to scale due to high costs and the lack of standardized recycling systems. Without a functional infrastructure or material uniformity, these programs remain largely symbolic. And even if these programs functioned as intended, they cannot address the microplastics we shed when walking and running. The uncomfortable truth is that we cannot recycle our way out of a materials problem.
While these efforts are commendable, they don’t solve the core problem: persistence. A shoemade with recycled plastic still becomes microplastic when it breaks down; that hasn’t changed. When the industry focuses only on inputs (raw materials) and ignores outputs (waste), it may tell a convenient story of progress without addressing the root issue: the material itself must change. True sustainability requires rethinking performance materials from the ground up, not temporary fixes, but permanent environmental solutions.
Across the world, innovators are developing biodegradable alternatives to conventional plastics. To name a few, in the U.S., Sway is transforming seaweed into compostable films for packaging. CruzFoam is creating biodegradable foams made from chitin — derived from shrimp shells — to replace polystyrene. In Europe, Notpla is making seaweed-based packaging. These companies are leading progress in single-use plastics, but footwear presents a far more complex challenge. In this space, one company is breaking new ground: Algenesis Labs, a San Diego–based startup founded at UC San Diego in 2016. Their Soleic® technology platform reimagines PU chemistry for biodegradability. Algenesis started by challenging the entire premise of PU design for the footwear industry. If nature is the ultimate recycler, breaking down materials into carbon dioxide, water, and biomass for reuse, then we must design materials whose chemistry is recognizable to current, natural biological systems.
The key innovation is how the material is fundamentally designed. We can chemically engineer the material to be robust during the material’s useful life, providing the required properties for the footwear industry, such as rebound, hardness, and density, as well as the ability to manufacture these biodegradable PUs in existing footwear manufacturing machines and factories. Crucially, however, we can also design chemical break points, sites that are specifically accessible to creatures in natural environments, enabling biodegradation.
In effect, designing a drop-in material that is engineered for high performance during use, and for rapid breakdown back into carbon dioxide and biomass post-use.
This approach makes a powerful statement: performance and end-of-life responsibility are not opposing forces; they are inherently linked and must be achieved together. The old assumption that a durable shoe must be environmentally persistent is simply false, especially in light of how frequently we replace them.
However, scientific validation is necessary. When a fully biodegradable plastic is developed, the standard for success is not how much recycled content it contains, its greenhouse gas reduction, or bio-content, but whether its eventual breakdown is completely safe for the environment. Wemust prove that what we create will not simply fragment like conventional plastic but will instead undergo complete mineralization without releasing toxic chemicals.
The industry currently relies on independent biodegradation standards to benchmark environmental safety. For example, testing protocols such as ASTM D5338 simulate the high-heat, high-microbe environment of industrial composting to assess whether materials can fully break down into carbon dioxide, water, and biomass. Another commonly referenced framework, ASTM D6691, seeks to replicate ocean-like conditions to evaluate biodegradation in marine environments.
While these tests are useful references, they are far from perfect. Accurately recreating the complexity of a true marine ecosystem in a laboratory remains scientifically challenging, and results can vary depending on testing conditions and microbial communities. Because of this, many materials innovators are working to advance new testing methodologies that reflect real-world biodegradation environments.
This distinction is essential: this is not fragmentation; this is mineralization. The plastic is designed to be safely consumed and converted entirely into carbon dioxide, water, and new biomass. This commitment to continuous scientific validation forms the foundation of a new materials economy, one where performance and environmental responsibility evolve together. In partnership with forward-thinking brands like BLUEVIEW® Footwear and NAMU Recovery, this technology is already being realized in high-performance products that meet the same demanding benchmarks for durability, comfort, and flexibility as traditional shoes, proving that the highest-performing shoe can also be the most environmentally responsible.
The technology to build truly disappearing footwear exists today; science is no longer the bottleneck. The real challenge now lies in adoption, supply chain transformation, and industry leadership. The industry faces a critical choice: continue with business as usual and accept the massive ecological and regulatory risk of persistent plastic, or embrace fundamental change.
A truly microplastic-free world requires more than just one brand's innovation; it demands deep,cross-functional collaboration across the entire supply chain. We must recognize that the pollution from our products is a shared global liability, meaning the fix can't come from a single company alone. To make this change happen, footwear brands must stop working in isolation and build a shared, sustainable ecosystem with scientists, material producers, and factories across the supply chain.
By successfully pioneering the adoption of biodegradable materials and scaling their supply chains, the footwear sector can become the essential case study and leader that drives fundamental change across other consumer goods. Our collective action, starting here, is the only path to shared, sustainable success.
The story of the footwear industry is shifting from plastic persistence to environmental responsibility. We now have the technology to eliminate the microplastic footprint of our shoes. The innovators of today will be remembered not for how fast their products ran, but for how quickly they stopped harming the planet.
This is no longer a question of if we can achieve a microplastic-free world, but how fast we choose to commit to it. The science exists, the materials exist, and the consumer demand is growing louder every day. What remains is the will to act. Every pair of shoes designed today will leave an imprint that lasts generations, either as a pollutant or as proof of progress. The choice is ours. The greatest legacy a product can leave is no trace at all.
illuminem Voices is a democratic space presenting the thoughts and opinions of leading Sustainability & Energy writers, their opinions do not necessarily represent those of illuminem.
See how the companies in your sector perform on sustainability. On illuminem’s Data Hub™, access emissions data, ESG performance, and climate commitments for thousands of industrial players across the globe.
illuminem briefings
Pollution · Wellbeing
illuminem briefings
Pollution · Nature
illuminem briefings
Pollution · Public Governance
Inside Climate News
Pollution · Nature
The Guardian
Pollution · Nature
Futurity
Carbon · Pollution