As awareness grows around plastic pollution's impact on ecosystems, a new solution has been heralded: biodegradable bags. Often marketed as an eco-friendly alternative to traditional plastic, these bags promise a reduced environmental footprint and faster breakdown in nature. Yet, the story isn't as straightforward as it seems. Beneath the green label lies an ongoing debate about how biodegradable bags truly impact the environment - especially regarding microplastics, those nearly invisible particles causing concern among scientists and environmentalists alike.

What are biodegradable bags?

Biodegradable bags are designed to break down more quickly than conventional plastic bags. They are typically made from plant-based materials like corn starch or sugarcane, or sometimes from other organic materials combined with certain types of plastic. Some biodegradable bags also use oxo-biodegradable additives, which promote fragmentation when exposed to sunlight or oxygen.

The premise behind biodegradable bags is that, unlike standard polyethylene plastic bags that can persist for hundreds of years, they will decompose into natural elements in a much shorter timeframe. For many, this sounds like an ideal solution: a bag that serves its purpose, then safely returns to the earth. But while the intentions are good, the reality can be more complex.

The microplastics' dilemma

Microplastics are tiny plastic particles, generally smaller than 5mm, that have made their way into virtually every part of our planet - from the deepest ocean trenches to the stomachs of animals and even our own bodies. These particles are generated when larger plastic items break down over time. They've been shown to harm marine life and potentially impact human health, given their persistence and ability to carry toxic chemicals.

Biodegradable bags are meant to reduce the microplastic problem, but not all of them achieve this goal. For instance, some bags only disintegrate into smaller plastic fragments rather than fully decomposing into non-toxic substances. This process, especially for bags labelled as "oxo-biodegradable" can result in microplastics entering the soil, water, and even the air, leading to further contamination.

In 2019, a study led by the University of Plymouth tested different types of biodegradable bags by exposing them to environmental conditions like soil, sea, and open air. The results were surprising: some bags claimed as "biodegradable" remained largely intact even after three years in the soil. This raised concerns about whether the bags were actually biodegrading as expected or merely fragmenting into smaller pieces. If the latter is true, biodegradable bags could unintentionally contribute to microplastic pollution, perpetuating the very problem they are meant to solve.

The problem with decomposition conditions

One of the main challenges with biodegradable plastics is that they require specific conditions to break down completely. Unlike organic waste like food or yard trimmings, which can decompose in natural environments, many biodegradable bags need industrial composting facilities to fully break down. Such facilities regulate temperature, humidity, and microbial activity to optimise decomposition. 

Unfortunately, access to industrial composting is limited, and the majority of biodegradable bags do not end up there. Instead, they are often disposed of in landfills, where they may lack the heat, light, and oxygen necessary for decomposition. When biodegradable bags are littered in nature or end up in the ocean, they are unlikely to find the conditions they need to break down fully, leading to prolonged persistence.

Misleading labels and public perception

The eco-friendly image of biodegradable bags can sometimes be misleading. Many consumers assume that "biodegradable" means that a bag will completely break down in nature without leaving a trace. However, as seen with oxo-biodegradable and certain plant-based bags, the term "biodegradable" does not guarantee harmless decomposition. Without proper disposal, some of these bags simply turn into smaller pieces of plastic, contributing to the accumulation of microplastics.

This confusion around labelling makes it harder for consumers to make informed choices. While terms like "biodegradable", "compostable" and "recyclable" all sound environmentally responsible, they each have different meanings and implications. Compostable bags, for example, are designed to break down under industrial composting conditions without leaving any toxic residue, unlike oxo-biodegradable bags, which break into plastic fragments. However, compostable bags are often disposed of improperly due to lack of awareness, negating their intended environmental benefits.

Regulations and the future of biodegradable plastics

In response to concerns around microplastics and misleading greenwashing claims, governments worldwide are starting to regulate the labelling and disposal of biodegradable and compostable plastics. For instance, the European Union has implemented new standards that restrict the use of oxo-biodegradable plastics due to their role in microplastic pollution. This type of legislation aims to ensure that products labelled as biodegradable meet rigorous criteria for degradation and environmental safety.

In the United States, certain states have begun setting standards for compostable products, while some cities are experimenting with bans on specific types of biodegradable plastics that fail to fully degrade in the environment. There is growing consensus that more regulation and standardisation are needed to ensure that biodegradable bags are genuinely eco-friendly.

For the industry to improve, more research and development are required. Scientists and manufacturers are experimenting with new materials, such as algae-based and mushroom-based plastics, that hold the promise of breaking down more completely in nature. If successful, these innovations could provide alternatives to traditional biodegradable plastics that can minimise the risk of microplastics while maintaining functionality.

Individual actions and community efforts

Despite the limitations of biodegradable bags, there are actions individuals and communities can take to reduce plastic waste and its impact. First, reusable bags remain one of the most effective ways to curb plastic consumption. By switching to cloth or sturdy reusable bags, people can minimise the need for single-use plastic and biodegradable bags alike.

Proper disposal and waste management are also crucial. Individuals can educate themselves about local recycling and composting options and advocate for improvements in waste management infrastructure. Communities can push for clearer labelling on biodegradable products to ensure people know how and where to dispose of them. Furthermore, supporting local and national policies aimed at reducing plastic pollution can drive change at a larger scale.

Finally, awareness campaigns can play a vital role in educating the public about the limitations of biodegradable plastics. The more people understand the complexities behind terms like "biodegradable" and "compostable", the better equipped they are to make environmentally responsible choices.

A path forward: combining solutions

While biodegradable bags offer a possible step forward, they are not a comprehensive solution to plastic pollution and the microplastics crisis. Addressing the plastic problem will require a combination of approaches, including reducing plastic production, improving waste management, and encouraging reusable alternatives.

For biodegradable plastics to be effective, further innovation is essential to ensure that these materials can fully decompose in a wider range of conditions. Additionally, stricter regulations and standards are needed to prevent products that merely fragment into microplastics from being marketed as biodegradable. And, as individuals and communities, we must advocate for policies that encourage sustainability and protect our environment.

In the meantime, the best solution may be to continue reducing our reliance on single-use items and prioritise alternatives that are truly sustainable. Until biodegradable bags can guarantee a zero-microplastic footprint, they should be seen as only one part of a larger, more complex approach to fighting plastic pollution. Our collective efforts, on both individual and policy levels, are essential in tackling this crisis and preserving the planet for future generations.

Conclusion

While biodegradable bags may appear as an ideal solution to our plastic problem, their impact on microplastics remains a concern. Without the right disposal methods and infrastructure, these bags can still contribute to pollution. Addressing this issue requires innovations, regulations, and widespread education. Only by tackling these challenges comprehensively can we move toward a more sustainable future - one that minimises the damage caused by plastic, in all its forms, and seeks to protect the ecosystems we depend on.

Renald Blundell is a biochemist and biotechnologist with a special interest in Natural and Alternative Medicine. He is a professor at the Faculty of Medicine and Surgery,

University of Malta