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If plastic is the problem, is next-gen biodegradable plastic the solution and will prevent plastic pollution?
in Plastic by (450 points)
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+4 votes

Not all biodegradable and bioplastics are the same and are sometimes, mistakenly, referred to as one or the other. It is useful to question the supplier of a product whose packaging is referred to with these terms - what exactly the material is made of, what exact conditions it will decompose under, what elements it will decompose into, how long decomposition will take, how to dispose of it, etc.

These are the different alternative plastics and what they mean:

  • Biodegradable plastics - Plastics that can be decomposed by the action of living organisms, usually microbes, into water, carbon dioxide, and biomass. Biodegradable plastics are commonly produced with renewable raw materials, micro-organisms, petrochemicals, or combinations of all three.
  • Bioplastics - Plastic materials produced from renewable biomass sources, such as vegetable fats and oils, corn starch, straw, wood chips, recycled food waste, etc. Also known as bio-based plastics or biobased plastics.
  • Compostable plastics - meet EN13432 or a comparable standard for compostable packaging so that the material decomposes/biodegrades in industrial composting conditions. Materials that meet an appropriate home composting standard can be composted in home composting systems.
  • Oxo-degradable plastics - Conventional plastics with additives called prodegredants that accelerate the oxidation process. While oxo-degradable plastics rapidly break down through exposure to sunlight and oxygen, they persist as huge quantities of microplastics rather than any biological material.

Let's go over the different problems with conventional plastics and if alternative plastics solve them:

  • There are so many different types of conventional plastics that it is hard to distinguish between them and determine how to dispose them. There are many different types of alternative plastics and it is hard to distinguish between them and determine how to dispose them.
  • Conventional plastics don't decompose easily and when they do they break down into microplastics. Most alternative plastics are designed to decompose in industrial environments only, although some may in home composting. Some are made of petrochemicals, including some home compostable ones, so could leave toxic residues or microfibres.
  • There are not enough facilities to recycle different types of conventional plastics. Alternative plastics are rarely recyclable, although they may be decomposable. Mixing them with conventional plastic recycling contaminates that too. There are currently very few facilities in most parts of the world to decompose alternative plastics (most UK recycling systems do not accept them).
  • Conventional plastics do not decompose in landfill environment. Alternative plastics do not decompose in landfill environment either. And slight decomposition could lead to the release of the greenhouse gas methane, due to conditions in an anaerobic environment.
  • Incinerating conventional plastics generates toxic chemicals. As many alternative plastics are made of petrochemicals, so may incinerating them. Incinerating others will generate the greenhouse gas carbon dioxide, although many are considered to be carbon neutral depending on what they are made of.
  • Conventional plastics released into the ocean are harmful to marine life. The ocean is not an ideal environment for breaking down alternative plastics. When released into oceans they will not break down easily and are harmful to marine life.
  • Conventional plastics poison our food chain when organisms like plankton eat them. As many alternative plastics are made of petrochemicals, so may they.
  • Conventional plastics are harmful to wildlife when wildlife gets entangled in them or feed on them. Alternative plastics will do the same.
  • Conventional plastics involve extracting fossil fuels. As many alternative plastics are made of petrochemicals, so will they. For others, there is high use of energy during production, which usually comes from fossil fuels.
  • Production of conventional plastics is harmful to the environment. There is usually high use of energy and water during production of alternative plastics. Some lead to deforestation. Some affect the food supply when land that could be used to grow food is used to grow their raw materials. Industrial farming practices for raw materials release chemicals into water bodies that kill aquatic organisms and increase acidification while excessive fertiliser application increases levels of greenhouse gas nitrogen oxide. The production & disposal, through running of machinery, causes carbon emissions.
  • Conventional plastics leach out toxic chemicals and may affect human health. As many alternative plastics are made of petrochemicals, so may they.

So it is clear that alternative plastics do not solve the world's plastic problems.


by (930 points)
edited by
+3 votes
This is quite a complex question to answer. Firstly we need to understand what the biodegradable plastics are. There are two main categories:
1.Bioplastics, which are made from natural materials like corn starch;
2.Biodegradable plastics that are made like regular plastics using petrochemicals that are engineered to break down quickly
The most common material used in bioplastics is Polylactide acid (PAL) produced out of corn kernels. It looks and behaves almost the same as polyethylene (PE) and polypropylene (PP). Production of it uses only a third of the energy required for traditional plastics. It is fully compostable.
Unlike bioplastics, biodegradable plastics are made of normal (petrochemical) plastics and don't always break down into harmless substances: sometimes they leave behind a toxic residue and that makes them generally (but not always) unsuitable for composting.
They may seem like the perfect solution but it is not that simple. Bioplastics for example, when they decompose on the landfill may still produce methane, which is a very powerful greenhouse gas. Because they look like PP and PE they may be easily mistaken with them and enter the traditional plastics' recycling stream which becomes contaminated. Also production of them requires the same resources as we need in agriculture: land, water, energy, pesticides etc. There is a huge risk of the food prices going up when farmers switch from growing food to bioplastics and biofuels. Also some bioplastic and biodegradable plastics require relatively high temperatures to decompose, which means it may take years for them to degrade.
In my opinion the volume of plastics we consume can't be replaced with the biodegradable options. We need to rethink our consumer behaviours, our addiction to packaging and convenience. They can be used as a last option but only reducing our use of any plastic is the best for the planet.
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