Last week, we talked about PLA, and today we wanted to talk about another bioplastic, oxo-biodegradable.
Traditional plastic is made from petroleum-based raw materials. Some say bioplastics—made from 20 percent or more of renewable materials—could be the solution to plastic pollution. The often-cited advantages of bioplastic are reduced use of fossil fuel resources, a smaller carbon footprint, and faster decomposition. Bioplastic is also less toxic and does not contain bisphenol A (BPA), a hormone disrupter that is often found in traditional plastics.
However, it turns out that bioplastics are not yet the silver bullet to our plastic problem.
Degradable, biodegradable and compostable… What do those terms mean anyway?
- Degradable – All plastic is degradable, even traditional plastic, but just because it can be broken down into tiny fragments or powder does not mean the materials will ever return to nature. Some additives to traditional plastics make them degrade more quickly. Photodegradable plastic breaks down more readily in sunlight; oxo-degradable plastic disintegrates more quickly when exposed to heat and light.
- Biodegradable – Biodegradable plastic can be broken down completely into water, carbon dioxide, and compost by microorganisms under the right conditions. “Biodegradable” implies that the decomposition happens in weeks to months. Bioplastics that don’t biodegrade that quickly are called “durable,” and some bioplastics made from biomass that cannot easily be broken down by microorganisms are considered non-biodegradable.
- Compostable – Compostable plastic will biodegrade in a compost site. Microorganisms break it down into carbon dioxide, water, inorganic compounds and biomass at the same rate as other organic materials in the compost pile, leaving no toxic residue.
Oxo-degradable plastics are used for checkout bags, flexible packaging and plastic sheets to protect crops and to inhibit weeds. You will find them in some food stores and supermarkets here in HCM where staff will fool you into thinking that you don’t need to bring your own carry bags as their bags are “biodegradable”.
Oxo-degradable plastics contain inorganic additives ─ metal salts ─ that are triggered by oxygen and UV light and cause the plastic to degrade. The plastic breaks down into minuscule particles but there seems to be no proof that this continues to levels which result in complete biodegradation.
Also, the presence of microplastics in the environment has a number of negative consequences for humans and the natural environment. If animals ingest pieces of plastic, large or small, mistaking them for food, a permanent feeling of satiety can result – and they starve to death.
In experiments feeding mussels with microplastics, researchers demonstrated that plastic particles could penetrate the stomach lining and enter the bloodstream. Many plastic parts contain chemicals like softeners or flame-retardants. Some of these additives are harmful to fertility or imitate natural hormones. They are only weakly bound into the plastic matrix, and can easily leach out and impact plant and animal life. Long-lasting hydrophobic pollutants can attach to and accumulate on plastic microparticles. If marine organisms consume these particles, these contaminants can enter the food chain (Teuten et al. 2007) and ultimately cause harm to humans.
A european directive that should come into force at the beginning of 2021 asks that member states define national targets for the reduction of disposable plastics, including a total ban on supposedly biodegradable plastic (oxo).
Want to know more and get answers to your questions about plastic? Make sure you come and attend our talks about plastic at the 2019 Holistic Fair, our panel will be first class!