A new peer-reviewed study claims that the two most common plastics on the planet can biodegrade fully in soil within two years, not centuries. The breakthrough hinges on a biodegradable plastic additive made by the company that funded the research, and the results come with important caveats that the headlines mostly skip.
The findings, published in the Nature Portfolio journal npj Materials Degradation, have been reported around the world as a clean breakthrough. But “plastics can now biodegrade in two years” oversimplifies what the study actually shows. A closer look reveals clear limits on which plastics this applies to, what they actually break down into, and whether the process is as clean and safe as the press release suggests.
This article separates the verified science from the vendor’s marketing claims.
What the New Study Actually Found
The study was a collaboration between Imperial College London, Malaysia’s Standards and Industrial Research Institute (SIRIM), and Polymateria, the UK biotechnology company that developed and sells the additive. It tested polyethylene (PE) and polypropylene (PP), the two most widely used packaging plastics, found in products such as plastic bags, cups, straws, films, face masks, and wipes.
The key result: samples of PE and PP that incorporated Polymateria’s “Biotransformation” additive broke down far faster than untreated plastic. According to testing carried out by SIRIM, the treated polyethylene biodegraded in 292 days and treated polypropylene in 269 days, both comfortably inside the two-year window highlighted in the study’s headlines.
Three specific findings stand out:
- More than 95% of the plastic’s molecular weight was lost during an accelerated ageing phase designed to simulate real-world outdoor exposure.
- The remaining material was then fully mineralised to carbon dioxide by soil microbes, meaning the plastic’s carbon was returned to the atmosphere rather than lingering as debris.
- Ecotoxicity testing found no adverse effects on test organisms in soil or water.
Crucially, the untreated “virgin” samples used as controls did not biodegrade. They persisted as normal plastic, which is precisely the point of the comparison.
Who Ran the Study, and Who Funded It
This is where scepticism is warranted. The study’s lead author is Dr Florence Huynh, who is Polymateria’s vice president of innovations. Polymateria is the commercial company that manufactures the very additive being tested.
The funding relationship does not stop there. Polymateria also sponsored the British standard that the study’s testing method is built on. That standard, BSI PAS 9017, was published in 2020 and defines what “biodegradable” means for polyolefin plastics in open-air conditions. Intelligent Living covered this standard when it was first introduced. SIRIM’s national ecolabel, SIRIM ECO 098, which the study is said to substantiate, is itself based on that Polymateria-sponsored standard.
To be fair, the actual testing was carried out by institutions with genuine independence. Imperial College London is a leading academic research university, and SIRIM is a Malaysian government standards and research body. Their involvement means the data was collected by third parties rather than by Polymateria’s own laboratory alone. The study was also peer-reviewed and published in a Nature Portfolio journal, which is a meaningful quality bar.
Still, a company funding research into its own product, using a standard it also funded, with its own executive as lead author, is a textbook conflict of interest. None of this makes the findings false, but it is exactly the kind of relationship independent scientists say should make readers cautious.
How the Additive Works: From Plastic to Wax to Carbon Dioxide
The mechanism is what sets this apart from older “biodegradable” additives, and understanding it matters. Traditional oxo-degradable additives work by causing plastic to fragment into smaller and smaller pieces, and those fragments are themselves microplastics. Polymateria’s claim is that its technology does the opposite: instead of fragmenting, the plastic undergoes a chemical transformation.
The process happens in stages:
- When the treated plastic is exposed to sunlight, heat, moisture, and air, it begins a chemical transformation rather than a physical breakdown.
- The long polymer chains are cut down into a wax-like substance that the researchers describe as “bioavailable”, meaning microbes can consume it.
- Naturally occurring soil microbes then digest that wax in much the same way they digest natural oils or butter.
- The end products are carbon dioxide, water, and microbial biomass, with no solid plastic and, the researchers say, no microplastics left behind.
A metagenomics analysis, which the researchers describe as first of its kind for this material, found no significant changes in soil microbiota composition after the process. It did record higher metabolic activity in the treated samples compared with virgin plastic, which the team interpreted as evidence that the wax was genuinely being used as a food source.
Does Plastic Really Take 1,000 Years to Decompose?
Part of the reason this study attracted attention is that it appears to contradict the familiar claim that plastic takes hundreds or even thousands of years to break down. That familiar claim is itself an estimate and a loose one.
A widely cited academic review published in the journal ACS Sustainable Chemistry & Engineering found that degradation time depends heavily on the type of plastic, its thickness, and the environment. For example, the review estimated that a high-density polyethylene bottle has a half-life of around 58 years in the marine environment, while a thicker HDPE pipe could take up to 1,200 years. Commonly quoted figures such as 450 years for a plastic bottle are generalisations that sit within this range.
The important distinction is that “breaking down” and “biodegrading” are not the same thing. A plastic bag left in the sun eventually fragments into microplastics, but that is not biodegradation. True biodegradation means microbes convert the material into carbon dioxide, water, and biomass. Untreated PE and PP do not do this on any meaningful timescale in nature, which is why they persist.
So the study does not really contradict the 1,000-year claim for normal plastic. It shows that treated plastic, with a specific additive, can biodegrade much faster. The untreated control samples in the study itself confirmed that ordinary plastic still does not break down. A few earlier biodegradable materials have shown real promise in home composting, but they rely on different chemistry than this additive.
Which Plastics It Works On, and Which It Does Not
The additive is designed for polyolefins, specifically polyethylene and polypropylene. That is a meaningful limitation, because the world uses many other plastics that this technology does not touch.
| Plastic | Works with this additive? | Typical behaviour in nature | Common uses |
|---|---|---|---|
| Polyethylene (PE) | Yes | ~292 days with additive; hundreds of years untreated | Bags, films, wraps, bottles |
| Polypropylene (PP) | Yes | ~269 days with additive; hundreds of years untreated | Straws, containers, masks, caps |
| Polyethylene terephthalate (PET) | No | Estimated 450 years or more | Bottles, polyester fibres |
| Polyvinyl chloride (PVC) | No | No measurable degradation after decades | Pipes, vinyl, cable insulation |
| Polystyrene (PS) | No | Hundreds of years | Foam packaging, cutlery |
| Polylactic acid (PLA) | No (different technology) | Months in industrial compost; slow in nature | Bioplastic cups, liners |
The takeaway is simple. If the packaging around you is PET, PVC, polystyrene, or any polymer other than PE and PP, this additive does not apply to it. Even for PE and PP, the additive has to be incorporated at the manufacturing stage. You cannot take an existing plastic bag and make it biodegradable after the fact.
Is the Wax Safe for Insects, Birds, and Soil Life?
One of the most reasonable questions is what happens to all the creatures that encounter the plastic and its breakdown products along the way. The study does address this, at least partially. The research included ecotoxicity testing on the wax that forms before full mineralisation, and the team reported no adverse effects on test organisms in soil or water. That is a real finding and a necessary safeguard, and it is also a specific requirement of the BSI PAS 9017 standard the study follows.
However, the picture is not entirely settled. The study’s testing was conducted under controlled land-based conditions. It does not tell us what happens in the ocean, in freshwater, or in landfill, where conditions are very different and where much of the world’s leaked plastic actually ends up. A 2020 review by the UK government’s Hazardous Substances Advisory Committee warned that there is very little long-term field data on the ecotoxicity of degradable plastic additives and that microplastic ingestion can act as an “energetic drag” on organisms even when it is not directly toxic.
There is also a broader point about scale. A single additive may pass ecotoxicity tests, but the environmental impact of billions of items degrading simultaneously, releasing carbon dioxide and altering soil chemistry at scale, is much harder to predict.
So the honest answer is this: the specific wax tested appears to be low-toxicity, but the evidence base for real-world safety across all ecosystems is still thin, and the study does not claim to cover marine environments.
The Caveats and Criticisms
Scepticism about degradable additives predates this study by years, and much of it remains relevant. The Sustainable Packaging Coalition, an industry body, has published a position that it does not support any degradability additives in petroleum-based plastics. Its reasoning includes several points that apply here:
- Additives can undermine the recyclability of plastic because a material designed to break down is harder to reprocess into a durable product.
- Degradation releases carbon. In open air this means carbon dioxide, but in a landfill, where oxygen is limited, it can mean methane, a far more potent greenhouse gas.
- “Biodegradable” labels can encourage littering. Consumer surveys have found that people are more likely to discard items they believe will safely disappear.
Independent reviews have been even more pointed. The UK recycling charity RECOUP, in a response to a government call for evidence, grouped “biotransformation additives” such as this one with oxo-degradable plastics, the family of additives widely criticised for merely fragmenting plastic into smaller pieces. Reviews commissioned from the consultancy Eunomia in 2018 and from University College London in 2023 reached a similar conclusion, finding substantial uncertainty around the central claims made for these materials, including the no-microplastic and no-toxicity assurances. RECOUP added that achieving full biodegradation under real-world conditions in the UK and similar cooler climates remains unproven.
Earlier analysis has even suggested that some so-called biodegradable plastics may be worse than conventional plastics for reducing pollution. There is also a legal dimension. Several US states, including California, Maryland, Minnesota, and Washington, restrict or ban unqualified “biodegradable” marketing claims, and the US Federal Trade Commission’s Green Guides treat degradable claims as deceptive when the product will not decompose within a year under normal disposal.
None of this means the study is wrong. But it does mean the technology should be judged on whether it delivers net environmental benefit, not just on whether a sample degrades in a test. The study itself frames the additive as a safety net for the estimated 32% of plastic packaging that leaks into the environment each year, rather than a replacement for reduction and recycling. That framing is more modest than the headlines suggest.
Frequently Asked Questions
Can plastic become biodegradable?
Yes, with modification. Ordinary PE and PP are not biodegradable in any meaningful timeframe, but adding the right technology, as this study shows, can make them biodegradable in soil. The catch is that this requires the additive to be added at manufacture, and it only works for certain plastics under certain conditions.
Does plastic ever fully decompose?
Untreated conventional plastics largely do not fully decompose in nature. They fragment into microplastics and nanoplastics over decades or centuries but remain chemically intact. This study’s treated samples, by contrast, were reported to mineralise fully to carbon dioxide.
How long does biodegradable plastic take to decompose?
It varies enormously. The treated PE and PP in this study reportedly degraded in 292 and 269 days, respectively. By contrast, many “biodegradable” plastics only break down in industrial composting facilities with specific heat and moisture and can persist for years if simply thrown into the environment.
Are bioplastics harmful to humans?
Bioplastics are made from biological materials and are not inherently safe or toxic as a category. The concern with plastics in general is less the polymer itself and more the additives, such as phthalates and bisphenol A, that can leach out. This study’s ecotoxicity testing found no adverse effects on the test organisms, but that is not the same as a full human-health assessment.
What are the top plastic polluters?
Single-use packaging is the largest source of plastic pollution, dominated by polyethylene and polypropylene items such as bags, films, cups, and wrappers. This is exactly why the study targets PE and PP: they are the most common plastics found as litter.
Conclusion
The study is a genuine and peer-reviewed advance. It provides evidence that treated polyethylene and polypropylene can biodegrade in soil far faster than conventional plastic, and it does so through a chemical transformation into a wax rather than by fragmenting into microplastics. That is a meaningful difference from older, widely criticised degradable additives.
But the claims deserve the careful reading this article has applied. The technology applies only to PE and PP, only when the additive is added during manufacture, and only in open-air terrestrial conditions. The funding and authorship sit heavily with the company that sells the additive; the long-term ecological picture is not yet established, and the technology does nothing to solve marine plastic pollution or the methane risk of plastics in landfill.
As a safety net for plastic that leaks into the environment on land, the technology is promising. As a reason to stop reducing and recycling plastic, it is not. The honest takeaway is that this is a real scientific step forward that has been marketed with a little more confidence than the evidence, on its own, can yet justify.
