Compostable Plastics: 3 Things You Need To Know

Plastics continually evolve. Science progresses, the market demand changes, health advocates push for improvements and new plastics are born. Compostable plastics are a new wave of plastics ... and with that wave comes an accompanying ripple of confusion. Here are three things you need to know about compostable plastics.

Compostable plastics are made from renewable materials
Compostable plastics are generally made from renewable materials like corn starch, potato starch, tapioca starch, cellulose, soy protein, and yes, even petroleum. The six most common plastic types are made from petroleum (HDPE, PET, PP, LDPE, PVC, PS), and are non compostable. However, there are some compostable plastics made from petroleum.

Compostable, biodegradable and degradable are not the same thing
These three terms are NOT interchangeable. This article focuses on compostable plastics and we'll discuss biodegradable and degradable plastics in follow up articles. In order for a plastic to be compostable, it must meet these three criteria:

1. The plastic must biodegrade. This means that the plastic can break down into carbon dioxide, water, and biomass at the same speed as paper.
2. The plastic must disintegrate. This means that the plastic breaks down to the point that you can't screen it out of the compost soil.
3. The plastic does not produce toxins. This means that as the plastic biodegrades it does not produce toxic materials and that the compost can support plants.

Most compostable plastics require a commercial composting system
Even though some plastics are compostable, your home compost system cannot generate the heat necessary to compost your plastics. So, don't throw your compostable plastics into your compost heap or bin ... because they most likely won't degrade.