Biodegradable ≠ Better? A Reality Check on Eco-Alternatives to Plastic

Welcome to Suits & Tides, the sustainability newsletter with more knowledge than microplastics in the ocean! In this episode, we’re talking about the truth behind so-called “biodegradable” plastics. What breaks down, what doesn’t, and why some eco-alternatives might be doing more harm than good.

Are Biodegradable Really the Greener Choice?

Do you think biodegradable items are always better than plastic? Think again.

We’ve grown up with the belief that biodegradable plastic is our golden ticket to solving the plastic crisis. With rising awareness about reducing plastic use from the upstream, more people, from businesses to governments, have started shifting toward plastic alternatives. And at the top of that list? Biodegradable plastic.

Over the years, headlines have praised these materials for degrading faster than traditional plastic. But what if new research challenges that belief? What if our so-called eco-friendly biodegradable plastic isn’t actually much better?

A joint research between UK and France research found some surprising truths. They tested and compared the degradation of plastic and biodegradable single-use items in both land and marine environments. A real world condition not just mere lab-based studies. The main goal of this study is to test if biodegradable single-use items actually degrade faster than plastic in a real-world environment. 

The shocking facts? Biodegradable items degraded faster in less than half of the test scenarios.

So, have we been fooled all this time? Let’s unpack what this means.

Why Does This Research Matters in a World Drowning in Waste?

Understanding how plastics (and their alternatives) break down isn’t just for academic purposes. It is crucial as it directly impacts how the government regulates waste policy and the industry designs packaging, and how we manage our daily activity.

The world is already overwhelmed by plastic waste, and we don’t have time to invest in false solutions. If no major interventions are made, researchers predict that by 2040, 710 million metric tons of plastic will be in environments. Aside from that, plastic pollution is a global and systemic threat for wildlife and food chains. 

Biodegradable plastic has become a popular go-to-solution. This practice is growing with the fact that many countries have adopted bans and policies targeting single-use plastics, like  Ireland reduced single-use bag consumption by 90%, or the EU with their ban on polystyrene containers, straws, cutlery usage. Dozens of countries such as the U.S., Australia, Canada, and India, also now charge every single plastic usage. 

However, many of these “biodegradable” plastics, like oxo-degradables, have blurry degradation claims. In some scientific studies, this plastic only breaks down because it was tested under lab-perfect conditions, not real conditions. This opinion is strengthened by the fact that biodegradation depends heavily on the environment. Some surveys also reveal a lack of standardization of methods and regulations, which makes it hard to know whether a product will actually degrade safely and fully.

This new research fills a huge gap. It’s one of the few in situ studies that tests how both biodegradable and conventional plastics behave outside of the lab, and the insights are crucial.

How the Study Was Done: Plastics vs. Biodegradables in the Real World

To assess whether biodegradable items actually degrade faster over plastics, Dalgaard Kjaer & Joly (2025) focused to compare biodegradable version and plastic of seven types of plastic: drinking straws, takeaway boxes, teabags, shopping bags, forks, chewing gum, and cigarette filters. 

The biodegradable materials are mainly made from polylactic acid or widely known as PLA and plant-based fibres like bagasse, cellulose, starch, and natural gum. The conventional plastics are made from polypropylene, polystyrene, low-density polyethylene, polyvinyl acetate, and 100 cellulose acetate.

The team tested both in marine and terrestrial environments in Scotland, UK. Using the classic litterbag method that is commonly used in ecology studies, they exposed 14 samples from each category to marine sites for 3.2 months and to terrestrial sites for 5.2 months. Once the fastest-degrading item showed near-complete decomposition, they ended the test, collected the samples, and measured the mass loss. 

What They Found: Sometimes Biodegradable, Sometimes… Not

Did the biodegradable items win? Well, yes and no. 

The study revealed that biodegradable plastics can outperform conventional ones but not at all. A nuanced picture of degraded plastics condition. 

Source: Dalgaard Kjaer & Joly (2025)

Terrestrial vs Marine Breakdown

In land or soil environments, biodegradable degrades faster than conventional plastic. Five out of seven biodegradable items show effectiveness of this material in terrestrial sites, not in aquatic sites, with only one out of 7 items degrading in these environments. These findings show that the advantage of biodegradable plastics would more likely occur in an environment prone to degradation or an environment with a high activity of decomposer organisms. 

Best performing materials

Another finding from this study highlights some biodegradable materials that truly degrades in terrestrial environments. Cigarette filters (degrades only in marine sites) and takeaways boxes (degrades at both marine and soil sites) outperformed conventional plastic degradation. These bio materials are mainly from plant-based materials such as bagasse and cellulose, while biodegradables that are made by PLA (polylactic acid) only decompose faster than their plastic counterparts in teabag forms. Beside that, PLA was not showing any degradation sign neither in terrestrial and marine experiments. 

What It Means: The Problem Isn’t Just the Material

Biodegradable does not mean you can toss it on the ground and expect it to disappear. Some materials degrade well in soil, but most struggle in marine conditions. Outside their ‘ideal’ conditions, many act just like regular plastic. 

This study makes it clear. Even biodegradable material needs proper disposal to break down safely and not leak to the environment. If it doesn't meet suitable conditions, biodegradable acts the same as conventional plastics. PLA (polylactic acid), for example, showed poor degradation in both sites despite their bioplastic label. 

Still, the findings also offer a silver lining. Plant-based materials can be considered as promising alternatives, due to their performance, for short lived items like takeaways boxes or cigarette filters.

But no matter how “green” the material is, waste handling matters just as much as what we make things from.

The Gaps: What This Study Couldn’t Tell Us (Yet)

• Short experiment duration : The experiment stopped as soon as the fastest items degraded. That means some slower-degrading materials like forks and straws didn’t get a fair chance. With this condition we can’t fully picture all the potential of all materials especially materials with slower degradation process. 
• Limited Scope: The study only focused on seven items. Not all biodegradable materials like PHA or biomass-blended PET are studied. So, results can’t be generalized to all “biodegradable” plastics.
• Microplastic risk: The mass loss method measures disappearance, but small fragments may escape the litterbags without fully degrading. The small fragments might escape from the litter bag rather than actual biodegradation. 

The findings are promising but we still need more comprehensive studies to confirm these gaps and show that biodegradable plastic truly breaks down safely over the long term.

The Road Ahead: Smarter Design, Not Just Different Material

To tackle plastic pollution, we need more than material substitution. We need to rethink the entire system. 

The UNEP’s Turning off the Tap (2023) report shows that there are three major shifts for real impacts which consist of reduce, reuse, and recycle. This effort helps cut 80% of plastic by 2040 by eliminating unnecessary plastics, improving reuse, and redesigning items for circularity.

The OECD’s Global Plastics Outlook (2022) also supports this statement by stating that our current recycling systems are inadequate and need stronger domestic policies and industry innovation. 

So yes, biodegradables are a helpful tool but not a silver bullet. Focusing on plant-based option as part of that ecosystem could make cleaner and sustainable outcomes that PLA or traditional plastics failed to achieve but making and strengthening the whole system still need to be our main priority. 

Bottom Line: Don’t Toss That ‘Eco-Friendly’ Just Yet

Here’s what Dalgaard Kjaer & Joly (2025) research’s is really telling us:

• Biodegradable ≠ automatic green
• Disposal conditions matter
• Some materials work and others don’t
• And real-world data beats assumptions every time

So, that’s why global experts like UNEP and OECD emphasize redesign and better waste management systems to tackle plastic pollutants. At Seven Clean Seas, we believe prevention is better than substitution.We focus on stopping plastic waste before it enters nature through recovery, innovation, and upstream solutions.We know the future isn’t just about replacing plastic. It’s about prioritising solutions across the waste hierarchy - using less, designing smarter, and building systems that work.

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