October 12, 2022

Did you know that bio-based, biodegradable, and compostable plastics are different things?

Bio-based plastics also called Bio-sourced plastics are plastics made (partially) from organic materials: some are identical to fossil-based plastics, such as bio polyethylene (PE) or bio polypropylene (PP), while some are polymers intended to be compostable.

Biodegradable plastics is not a regulated term so it’s not unambiguous. This term refers to plastics that are degradable through the action of naturally occurring microorganisms such as bacteria, fungi and algae. It gives the wrong idea that such material is harmless if littered. As long as the degradation is not complete, the polymer remains harmful for the environment. The kinetic of degradation depends on the environment (humidity, light, salinity, temperature, etc.). They can be also of petrochemical origin, such as polycaprolactone (PCL).

Compostable plastics are plastics which degrade through the process of composting, which is a controlled aerobic process.

Industrial composting conditions require an elevated temperature combined with a high relative humidity and the presence of oxygen. EN 13432 is a product norm for packaging materials, not a waste treatment norm, and complying with it cannot be considered a guarantee of complete industrial compostability.

Home composting conditions have lower and less constant temperatures, making it a slower process, depending on the type of material. The existing standard for home composting is NF T 51800.

  • Today, some bio-based plastics do not biodegrade in bio-waste treatment plants and none degrade completely in the natural environment (including waterways). Compostable plastics do not degrade in anaerobic conditions (AD) unless followed by an aerobic process and given the difficulty to distinguish between compostable plastics and conventional plastics, even if they are correctly disposed of by the householders, they are likely to be sorted out at the composting plant and sent for recovery.
  • Biodegradable plastics are also problematic when they are mixed with recyclable plastics as they do not have the same material properties and may impact the integrity of the recyclates. The use of biodegradable plastics must be so specific that the correct recycling route is clearly identifiable for the consumer/user. The mere risk that this might happen has already been known to discourage manufacturers to use recycled content.
  • Biodegradable plastics also have a negative impact on littering. The biodegradation process takes weeks or even months. Further research and innovation to develop biodegradable plastics is therefore important. Plastic packaging with unconditional and quick biodegradable properties would indeed offer environmental benefits. Consequently, we see the promotion and widespread marketing of biodegradable materials at this stage as potentially problematic.

FEAD supports the use of bio-based plastics as long as they are not promoted at the expense of recycled plastics. For a more extensive analysis of the impacts of bio-based and biodegradable plastics on waste and of how bioplastics can help achieve sustainability objectives, see FEAD’s relevant position paper.