The persistence trap

On April 6, 2026, the U.S. Environmental Protection Agency (EPA) officially proposed listing microplastics as a priority contaminant group on its draft Sixth Contaminant Candidate List (CCL 6) under the Safe Drinking Water Act. While this move is a vital step toward safeguarding our drinking water, it carries serious risk of regulatory oversimplification.

If the EPA adopts a rigid, one-size-fits-all definition of microplastics, federal policy will accidentally penalise the very materials engineered to solve the crisis. To avoid the structural mistakes of past compostability laws, new regulations must draw a sharp line between persistent pollution and transient biodegradation.

The inevitable "micro-stage"

From a materials science perspective, fragmentation is an inescapable law of physics. Mechanical wear and environmental exposure cause every material on Earth, whether natural or synthetic, to shed. A 100% wool sweater sheds micro-fibres in a washing machine, a natural rubber shoe sole sheds micro-particles on pavement, and a bio-based polyurethane sheds during use and fragments under sun exposure. Everything passes through a temporary "micro-stage."

Because of this, defining a substance strictly by its physical size (traditionally anything under 5 millimetres) is a fundamental regulatory flaw. The true danger to an ecosystem is not the brief existence of a microscopic particle, but its chemical permanence.

When a conventional PET water bottle fragments, its polymer chains remain entirely intact. It shatters into billions of microscopic, non-biodegradable pieces that persist for centuries, absorbing ambient toxins and working their way into the environment, including the food chain. On the other hand, when an advanced biodegradable bio-polymer fragments, its micro-stage is merely a brief pitstop on the way to complete biodegradation. Soil and water microbes recognise its chemical bonds as a food source and convert them into carbon dioxide, water, and biomass.

By regulating a particle's size rather than its environmental residence time, we risk banning materials specifically engineered to safely disappear.

Escaping the 90-day trap

Current compostability frameworks, including California's truth-in-labelling plastic regulations and international standards like TÜV OK compost INDUSTRIAL, share a critical blind spot: they mandate a strict 90-day disintegration timeline. While this rapid timeline works well for thin films, single-use straws, and food packaging, it entirely ignores the physics associated with durable materials.

High-performance goods like shoes, automotive parts, and outdoor gear are meant to withstand years of active use. Expecting a material to maintain its structural integrity during a long useful life and then suddenly vanish in three months is a fundamental contradiction. If manufacturers are forced to meet rigid 90-day standards, products could fail prematurely, potentially while in use or even before they reach consumers.

True circularity requires regulators to decouple a product's useful life from its end-of-life. A high-performance bio-material should remain completely stable until it enters a managed waste environment. If an advanced polymer takes one to three years to fully biodegrade once disposed of, it is still a massive environmental victory compared to traditional plastics that last for centuries.

Federal policy should reflect this reality through a tiered regulatory framework:

• Tier 1 (Rapid): Materials degrading in under 180 days, ideal for single-use packaging.
• Tier 2 (Durable-Bio): Materials degrading over one to three years, tailored for high-performance hard goods and textiles.
• Tier 3 (Persistent): Materials that persist for centuries, which should face strict regulation and "polluter pays" fees.

The infrastructure bottleneck

Introducing these categories also demands an honest look at our waste management system. A tiered regulatory framework cannot exist in a vacuum. If regulators recognise materials that biodegrade over a one-to-three-year window, our infrastructure has to evolve alongside the policy. Industrial composters built around rapid 90-day processing cycles are simply not equipped to handle longer degradation timelines.

Bridging this gap requires an integrated system focused on two areas. First, we need automated sorting and traceability. Products must be clearly identifiable by their specific degradation tier using something like a Digital Product Passport (DPP) that syncs with sorting technologies at waste facilities. Without automated verification, facility operators won't risk contamination. We see this issue clearly in Germany, where many industrial composters reject certified biodegradable products outright simply because workers cannot visually distinguish them from conventional plastics.

Second, we must set up targeted collection systems. Instead of tossing these durable bio-materials into the regular trash, dedicated disposal pipelines should route them straight to specialised facilities equipped to handle longer composting cycles. Policy must do more than just incentivise the creation of Tier 2 materials; it must actively subsidise the expansion of the infrastructure capable of processing them. Otherwise, we will end up with innovative materials approved in theory but rejected in practice because the infrastructure to handle them does not exist.

Ensuring chemical safety

The microplastic crisis is about more than just physical particles; it is also about the "Trojan Horse" of chemical toxicity. Traditional plastics are routinely loaded with phthalates, PFAS, and heavy-metal catalysts that leach into ecosystems and the human body. To be truly circular, a material's micro-stage must be inherently non-toxic and bio-assimilable.

A new generation of innovators is already proving that safety can be engineered into every tier of the material economy. At the entry tier, companies like Notpla use natural seaweed extracts for single-use packaging. Their chemistry is fundamentally edible and devoid of synthetic stabilisers, allowing micro-fragments to disappear from the food chain in a matter of weeks.

To tackle the specific issue of abrasion microplastics, Kuori repurposes food side-streams like olive pits into elastic materials for shoe soles, ensuring that the dust shed from everyday walking is chemically inert and recognised by soil microbes as organic matter.

Representing the durable tier, Algenesis Labs has developed Soleic, a biodegradable polyurethane designed for applications requiring a long service life. Materials in this category illustrate why regulators should distinguish between temporary micro-particles that ultimately biodegrade and persistent plastic fragments that remain in the environment for decades or centuries. The central policy question is not whether a material passes through a microscopic stage, but whether it persists indefinitely once it does.

The path forward

The ongoing development of the EPA's contaminant frameworks presents a critical window for the scientific and business communities to advocate for a smarter definition of microplastics. Brands developing durable bio-materials must engage with upcoming federal standards to ensure that future federal frameworks define microplastics by their environmental permanence rather than their physical size. This shift is essential to prevent well-intentioned policy from accidentally banning the very innovations engineered to solve the plastic crisis.

If a bio-based microparticle that disappears within two years is treated the same as a PET fragment that persists for centuries, we risk stalling the exact technologies capable of solving the problem. It is time to align federal policy with modern chemistry, ensuring that plastic finally becomes a temporary state of matter rather than a permanent environmental legacy.

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