Plastic that is biodegradable? Great, let’s have it! STOP! Not so fast. Unfortunately, the term bioplastic is a little bit misleading and a whole lot confusing.
For instance, biodegradable plastics can be manufactured either from fossil sources, like crude oil, but also from renewable materials, like corn, sugar canes and leftovers from food production. Then there are also plastic blends which are a mix of fossil-based plastic and plant-based plastic. And finally, all aforementioned types of plastic can be biodegradable or non-degradable. Are you confused yet?
Let’s start with the wide spread misconception that bioplastic is always biodegradable. In the case of biodegradable plastics made of fossil sources, full decomposition is only possible under certain industrial conditions. But the same also applies to most of the bioplastic produced from renewable raw materials e.g. PLA (polylactic acid), that is typically made from the starch in corn, cassava or sugarcane, but is biodegradable only in an industrial composting plant. The decomposition process proceeds very slowly and in case of biodegradable plastic from fossil fuels no valuable compost ingredients, such as nutrients, minerals or soil-improving humus are released, meaning no substrate is developed. Meaning if you throw a cup made from biodegradable plastics on your home compost heap, it will not decompose. You might as well throw a plastic bottle there (please, do not!).
Biodegradable plastics are also manufactured in comparatively low quantities so that the establishment of a dedicated recycling infrastructure is difficult. This is why bioplastics in many countries are discarded as contaminants at composting plants and incinerated.
Bioplastic is often advertised as more „environmentally-friendly“ than traditional plastics, but when the materials’ life cycles were taken into consideration, that’s not necessarily always true. The production of bioplastic creates additional pressures on the environment through the use of fertilisers, pesticides and agricultural machinery, as well as the consumption of water. The land requirement for the cultivation of a monoculture stands in competition with food production and the use of genetically modified plants cannot be ruled out. Conventional cultivation and processing of plants causes acidification of soils and eutrophication of water bodies. In addition, the chemical processing needed to turn organic material into plastic can, similarly to fossil sourced plastic materials, include hazardous additives and the effects of some of these substances on the environment and health are not entirely clear. However, if the source of the material for bioplastic production is discarded food waste e.g. rice husks, banana peels, coffee grounds etc. the effect on the environment could potentially be positive, as it would keep organic waste from the landfill and wouldn’t need additional agricultural efforts.
As always, there is no easy solution for such a complex problem that is plastic use. We suggest to prefer buying products without plastic packaging (or as little as possible), bring your own durable alternatives (beeswax wraps, glass cans) and recycle your packaging properly. And finally, before throwing anything on your compost heap, make sure that the material is home compostable (not just biodegradable) and do a little research to determine that the producer’s claims aren’t greenwashing.
Author: Triin Sakermaa, firstname.lastname@example.org