Breaking down bioplastics

Breaking down bioplastics
27 Mar 2020

Breaking down bioplastics

“Bioplastics” is a term that frequently arises in the media and public domain, and is often touted as the answer to the plastic pollution problem.

Unfortunately, the term is often incorrectly used to describe a few different concepts, which can create a lot of confusion in the marketplace.

Here’s a handy guide to the key concepts, which can help you as a consumer make sense of the topic and make better choices:

The first thing to note is that plastics can be made from either fossil-based (derived from petrochemicals) or bio-based (plant-based) materials.

  • Biodegradable plastics breakdown in a defined period of timebut this does not mean that they should be freely released into the environment in an uncontrolled manner. The speed, method and nature of biodegradation differs between materials. They are not currently recycled in the same way as non-biodegradable plastics and have to be dealt with separately. South Africa does not currently have commercial facilities that can handle biodegradable packaging. Not all biodegradable plastic is compostable.
  • Compostable plastics must meet a particular international standard in order for the material to decompose and biodegrade adequately in industrial composting conditions. While there are no toxic side effects to this process, compostable plastic packaging must be clearly labelled and easy for citizens to identify, separate and correctly dispose of in the specific collection and recycling scheme for compostable plastics. All compostable plastic is biodegradable.

What makes biodegradable and compostable plastics problematic is the lack of clarity concerning the standards that define their biodegradability. There is a particular lack of evidence on the behaviour of these materials in water or at lower temperatures. Therefore, it is very difficult to accurately assess the environmental impact of biodegradable and compostable plastic packaging.

  • Bio-based plastics are plastics derived entirely or partially from renewable resources, such as vegetable fats and oils, corn or starch. Conventional fossil-fuel plastics are derived from the by-products produced when making petroleum. The use of renewable resources as feedstock in the production of bio-based materials is seen as a way of reducing the dependency on oil. Bio-based plastics are not always biodegradable.
  • Oxo-degradable plastics degrade when exposed to heat and/or light. Certain additives serve to initiate and accelerate break-down of the plastic by a process known as “oxidative degradation”. Exposure to heat and/or light causes the molecules to break apart so that the plastic weakens in strength, becomes brittle and fragments into small pieces.

The time taken for oxo-degradable plastic, like some carrier bags, to start to degrade will depend on the amount of additive in the plastic and the type of environmental conditions it is exposed to. Therefore, it is not possible to accurately predict when the plastic will start to degrade. Too quickly and it could create product quality and integrity issues; too long and it could compound the potential for microplastics to leak into our environment. PETCO supports the Ellen MacArthur Foundation’s position on oxo-biodegradable plastic, which is that oxo-degradable plastic packaging is not a solution to plastic pollution, and does not fit in a circular economy.

PETCO is opposed to the use of biodegradable additives in PET because:

  • It contaminates the recycling stream.
  • It may encourage littering if the public think the material will “disappear”.
  • Degradation leads to fragmentation, making it harder to collect the material.
  • Even if the plastics don’t degrade until they end up in landfill, they should not degrade once there. Degradation can release methane and carbon dioxide emissions, which requires further treatment on landfills.
  • Even if it is a small dose of additive, the cumulative effect of all additives in their various forms is of concern.
  • Promoting degradation of any kind moves us away from the circular economy and back towards a “make, take, dispose” form of consumption.

Any plastic or other material that evades appropriate collection and treatment and then escapes into the environment has the potential to have a long-lasting impact on the environment. For all plastics, recycling generates the lowest emissions at end of life. 


Image Source: Bioplastic News