The problem with biodegradable plastics

As companies attempt to make their products more environmentally friendly and appealing to customers, many are turning to so-called biodegradable or compostable materials. But unfortunately research shows these bioplastic alternatives may sound a lot better than they perform. Bottom line: they aren’t necessarily better for the environment than traditional plastic materials.

Bioplastics are materials made from vegetable fats and oils, corn starch, recycled food waste, straw, woodchips, and more. While this sounds like a good replacement for plastic—there are actually downsides to switching from plastics to so-called biodegradable plastics and compostable fibers.

Bioplastics and plant-based materials can contain toxic chemicals, the products don’t decompose in the environment, and they can’t be recycled. In fact, they can actually harm recycling. If placed in the recycling bin, these materials can cause the recycling process to be contaminated, sending more trash to the landfill, ultimately causing more harm to the environment. It’s an easy thing to do because many may assume bioplastic belongs in the bin with regular ol’ plastic.

To understand why these materials aren’t the solution, let’s look at a few replacement materials being used:

Corn-Based Plastics
Many food containers are made from polylactic acid (PLA), made from corn, sugar cane, or other plants. The labels on these items often state that it is compostable. But this is only the case if it decomposes in a commercial facility (often not available in many parts of the country). One can’t simply throw their “corn-based” salad container into their backyard compost. These items require specific conditions, including extreme heat and precise moisture control in order to break down. Many think the items are recyclable because they often look like PET plastic (which is highly recyclable). But, if recycled incorrectly, corn-based plastics can contaminate the recycling process. And, if thrown into a landfill, the material will take a long time to decompose.

Paper Materials
While not not advertised as biodegradable, people may assume paper cartons are. Afterall, they’re paper, right? But the switch to paper cartons, such as a juice box or boxed water, isn’t a viable solution. Yes, paper can be recycled. But here’s the problem: Paper-based cartons aren’t just paper. They are made with various layers of material, including foil and/or plastic lining. This prevents it from being 100 percent biodegradable and it also makes them difficult to recycle.

Fiber Materials
Similar to corn-based plastics, some companies are shifting to fiber materials to replace food service containers. Fiber alternatives are a byproduct from sugar cane mills, called bagasse. These containers are often marketed as compostable. But not many people have access to composting, so the majority of these containers end up in landfills, adding to the problem. These also cannot be recycled and can cause problems for recycling centers if disposed of incorrectly.

PHAs
Polyhydroxyalkanoates, or PHAs, are bioplastics synthesized from bacteria. But producing this material economically has been a challenge, making it a less viable alternative for many companies. One article notes the disadvantages in practical applications: “poor mechanical properties, high production cost, limited functionalities, incompatibility with conventional thermal processing techniques and susceptibility to thermal [heat] degradation.” Additionally, one recent study found it could take years for PHA to biodegrade in the environment.