A recent study published in Environmental Science and Technology has raised concerns about the effectiveness of biodegradable plastics. Researchers discovered that some plastic bags, marketed as biodegradable, can still function as fully intact shopping bags even after being disposed of for three years. This challenges the popular belief that these products break down rapidly in natural environments, highlighting the complexity of plastic degradation and its environmental impact.
The study examined four types of plastic bags: biodegradable, oxo-biodegradable, compostable, and standard plastic bags. The researchers placed these bags in three distinct environments — left exposed in open air, buried in soil, and submerged in seawater — to evaluate how they degraded over time. Surprisingly, many of the biodegradable options performed worse than expected.
In particular, oxo-biodegradable and standard high-density polyethylene (HDPE) bags stood out as the most resilient. HDPE bags are the everyday plastic bags you’d find at your local grocery store, while oxo-biodegradable bags are designed to degrade more quickly under certain conditions. However, both types of bags were still capable of holding a full load of shopping after three years in both soil and seawater environments. This finding is especially concerning, as oxo-biodegradable bags are often marketed as a greener alternative to conventional plastic.
While some of the tested bags did eventually break down into smaller fragments, this didn’t necessarily mean they had fully degraded in an environmentally friendly way. Fragmentation into microplastics, tiny plastic particles that pose serious environmental and health risks, was observed as a potential outcome. Microplastics can persist in ecosystems for extended periods, accumulating in the food chain and affecting marine life and humans alike.
The study’s findings shed light on the misconception that all biodegradable plastics are a sustainable solution to plastic pollution. Compostable bags, on the other hand, were shown to break down more effectively, particularly when exposed to specific composting conditions. However, even compostable plastics require industrial composting facilities to degrade properly, meaning that they won’t fully break down in regular soil or ocean environments as some might assume.
This research highlights the need for stricter standards and clearer labelling around biodegradable and compostable plastics. Consumers often choose biodegradable plastics with the assumption they will degrade quickly and safely, but these findings suggest that some of these products may still contribute to long-term environmental harm. As plastic pollution continues to be a pressing global issue, it’s critical that industries, governments, and consumers are better informed about the true impact of the materials they use.
Ultimately, the study serves as a reminder that reducing plastic waste through more sustainable practices — such as reusing bags, opting for truly compostable materials, or eliminating single-use plastics altogether — remains one of the most effective ways to address the growing plastic problem. Until biodegradable plastics can be proven to degrade fully in all environments, they may not be the environmental solution they are often promoted to be.
For more on this, or to conduct a full waste management audit, contact Wanless Waste Management’s team today.