Is it true that bioplastics are a sustainable alternative to plastics since they degrade quickly in nature?

This claim is certainly false. Some of the materials called “bioplastics” are only biobased (made from renewable resources) but not biodegradable. Other materials called “bioplastics” are biodegradable but need very specific conditions to disappear quickly enough. However, these conditions are often not found in nature. If biodegradable plastics end up in the wrong place, they won’t biodegrade quickly and completely.

Detailed information

When plastic degrades, it fragments into smaller pieces, and eventually micro- and even tinier nanoplastics. This can happen to all plastics, including the conventional kinds.

For a plastic material to disappear completely, it needs to be “bio”-degradable and disposed of in a location that enables actual and complete biodegradation. Depending on the biodegradable plastic, this suitable environment can be an industrial composting plant, a biogas plant, home compost, or another clearly defined environment.

Biodegradation is a process by which microbes turn a material into water, biomass, carbon dioxide or methane (sometimes also minerals). Biodegradable plastics can thus be broken down into building blocks that also occur in nature. However, this needs to happen in a reasonable time frame under specific conditions, such as the presence of microbes, certain temperature, humidity, available nutrients and oxygen. These natural conditions vary from environment to environment. That’s why, depending on location, biodegradable plastics may only biodegrade partly, slowly or not at all.

Biodegradability is not tied to the source of the material. Biodegradable plastics can be made from fossil and/or renewable sources.

According to scientific studies, biobased and/or biodegradable plastics can have the same impact on human health as conventional plastics, due to the chemicals added. They also have an ecological impact on other levels, so that bioplastics are not generally more sustainable than conventional synthetic plastics.

However, biodegradable and/or biobased plastics can be useful for some applications. Biobased plastics can help to move away from an economy based on fossil fuels. And biodegradable plastics are used as medical implants, as mulch foil for agricultural fields, or for the collection of organic waste. Whether or not they have benefits depends strongly on each application and local case. Of all plastics currently produced, only a small fraction is biobased and/or biodegradable.

Sources

Expert check

Thanks toFrederik Wurm of University of Twente for scientific fact-checking, andLinda Amaral-Zettler of the Royal Netherlands Institute for Sea Research (NIOZ) for feedback on earlier draft.

Updated on: October 26, 2023