The report, “Addressing Persistent Plastic Pollution: The Case for Biodegradable Solutions,” finds that whilst biodegradable materials do fragment into microplastics as part of their breakdown process, these particles are transient and continue to biodegrade through microbial activity, unlike conventional plastics which persist indefinitely in the environment.
Evidence from case studies in agriculture, forestry, and composting demonstrates that when properly managed under supportive regulatory frameworks, biodegradable plastics break down at a similar rate to which they are introduced into the environment, preventing long-term accumulation. Research shows that biodegradable agricultural mulch films can reach steady-state concentrations in soil rather than building up over time, with field trials confirming materials continue to degrade and eventually mineralise into carbon dioxide, water, and biomass.
Gail Shuttleworth, the report’s lead author from Alder BioInsights, explained: “In contrast to conventional microplastics, genuinely biodegradable microplastics are transient and will undergo full mineralisation when exposed to the appropriate environmental conditions. This fundamental difference makes them a key tool in tackling microplastic pollution from plastics used in, or prone to, entering the open environment.
“Moreover, robust regulations and internationally recognised standards such as those for biodegradability and compostability have driven innovation, ensuring that certified materials meet verified biodegradation benchmarks and providing confidence that these alternatives deliver genuine environmental benefits.”
The report examined key applications where biodegradable materials are used in open environments. Biodegradable agricultural mulch films, certified under European Standard EN 17033:2018, must convert at least 90 per cent of organic carbon to carbon dioxide within 24 months. Whilst real-world field conditions can slow this process, studies demonstrate that equilibrium develops between new film application and the breakdown of existing plastic fragments, preventing long-term build-up.
Industrial composting trials across multiple countries showed that certified compostable plastics effectively disintegrated within 22 days, with some items such as polylactic acid plant pots fully breaking down in just 11 days. The EN 13432:2000 standard requires 90 per cent biodegradation within six months and less than 10 per cent visible residue after 12 weeks.
Dr Adrian Higson, Managing Director of the Alder BioInsights and one of the report’s authors, stated: “Our report demonstrates that biodegradable plastics can play an important role in avoiding persistent microplastic pollution.”
The report draws on industrial-scale trials previously conducted by Envar Composting through the UKRI-funded Composting Coalition. In routine operations, a range of certified compostable items showed steady breakdown profiles under standard industrial composting conditions.
James Cooper, Head of Compliance at Envar Composting, said: “Our job was to prove what happens in practice, not just on paper. In our trials for the Composting Coalition, certified compostable materials broke down cleanly when managed through standard industrial composting. Crucially, our analysis found no detectable compostable-plastic microplastics in the screened product. That’s what matters to farmers and growers – the output is clean and fit for purpose.”
Research cited in the report demonstrates that even when biodegradable materials don’t fully break down during composting, the process continues once compost is applied to soil. Biodegradable microplastics like polylactic acid undergo further biodegradation driven by soil microbial activity, meaning they continue to break down rather than persisting in the environment.
The report highlights innovation in biodegradable tree guards, where new materials are being developed to protect trees for five to seven years before degrading over approximately two years, addressing the challenge of longer degradation times in ambient conditions.
A 2024 meta-study confirmed that biodegradable microplastics continue to break down in soil environments primarily through hydrolysis, preventing accumulation of persistent microplastic fragments. This contrasts sharply with conventional plastic microplastics, which remain in soil indefinitely.
The report makes eight key recommendations including establishing application-specific biodegradation standards, supporting research into acceptable mineralisation timeframes, funding long-term environmental fate studies, and developing global monitoring frameworks for microplastics from both conventional and biodegradable sources.
This BB-REG-NET report emphasises that while biodegradable plastics are not a complete solution to microplastic pollution, they offer a fundamentally different trajectory from conventional plastics. With appropriate product design, use, and regulatory oversight, biodegradable and compostable materials can significantly reduce long-term persistence of microplastics in the environment.
The report is available to download from bb-reg-net.org.uk/resource-hub.
