Bio-based synthetics are a new generation of fibers made from plants instead of petroleum. This sounds like a perfect solution, but the truth is more complex. The term "bio-based" does not automatically mean a material is good for the environment. At Circular People, we believe in transparency and research, and we avoid non-circular inputs. We believe you must choose these materials wisely.

The Difference Between Bio-Based and Biodegradable

This is the most important distinction to understand.

• Bio-Based: The material comes from a plant, like corn or sugarcane, instead of a fossil fuel. This is a positive step that reduces our reliance on petroleum.

• Biodegradable: The material can be broken down by microorganisms and safely returned to the earth.

Here’s the catch: many bio-based synthetics are chemically identical to traditional plastics and are not biodegradable. They will still shed microplastics in the wash and will not break down in a landfill.

Understanding the Bio-Polymer Landscape

To make an informed choice, it's crucial to know the difference between the main types of bio-based synthetics you'll see on the market. We've broken them down into three categories based on their circularity and end-of-life fate.

• Avoid "Drop-in" Synthetics (e.g., Bio-PET, Bio-PA): These materials are the most common type. They are made from plants (like sugarcane or castor beans), but they are chemically identical to traditional plastics. Their main benefit is at the start of their life, as they reduce the demand for fossil fuels. However, they are not biodegradable at all. They will still shed microplastics in the wash and will not break down in a landfill for centuries. Because their end-of-life is the same as conventional plastics, they are a non-circular input that we believe should be avoided. 

• Be cautious with Polylactic Acid (PLA): PLA is a bio-based synthetic made from corn starch or sugarcane. A key advantage is that it is designed to be biodegradable. However, this comes with a major caveat: it is not home compostable. PLA requires a very specific, high-heat environment found only in a commercial, industrial composting facility to break down. If a PLA product ends up in a regular landfill, it will not decompose. This makes it a better option than a "drop-in" synthetic, but it requires a careful look at your local composting infrastructure to be a truly circular choice.

• Acceptable and promising is Polyhydroxyalkanoates (PHA): PHA is currently the most promising and truly circular bio-based synthetic. Made by microorganisms, it is not only sourced from plants but is also designed to be fully biodegradable in a wide range of natural environments, including soil, freshwater, and marine conditions. This means that if it were to accidentally end up outside of a composting facility, it would safely return to the earth without intervention. While still a niche material, PHA represents a genuinely circular solution that aligns with our core values.

How to Shop Smart

When you see a product labeled "bio-based," it's crucial to look for more information.

• Read the Fine Print: Don't assume "bio-based" means "biodegradable." Look for clear end-of-life instructions.

• Look for Agri-Waste Feedstocks: To avoid the "food vs. fuel" debate, support brands that are moving toward using second-generation feedstocks like agricultural waste or captured carbon. This is a sign of a truly innovative and responsible approach.

• Look for Certifications: The USDA BioPreferred® Program and TÜV Austria OK biobased labels certify the percentage of renewable content.

• Choose Well: The most sustainable garment is one that lasts. When possible, choose fully biodegradable natural fibers like wool or linen. If you choose a bio-based synthetic, ask the brand if it's designed to be recycled or safely composted.

End of Life and Circularity

The most sustainable materials are those that have a clear, safe, and scalable end-of-life path.

• For "Drop-In" Bio-Synthetics (Non-Biodegradable): These materials are non-circular, so we avoid them. They will persist in landfills for centuries, just like traditional plastics.

• For Biodegradable Bio-Plastics (PLA & PHA): These are the most promising. They can be safely returned to the earth. For PLA, this is through industrial composting; 

• PHA, or polyhydroxyalkanoate, is generally considered both compostable and biodegradable (in landfills). The material will break down naturally into harmless substances like water and carbon dioxide through the action of microorganisms. If composting, consider the dyes and finishes used.

When you choose materials, always ask yourself: "Where will this go at the end of its life?" For truly circular materials, the answer should be a safe return to the earth.