Plastic pollution has been globally recognised as a serious environmental problem. As a result, a number of initiatives have been launched to combat plastic pollution, most prominently the recent EU Directive on the reduction of the impact of certain plastic products on the environment; in short, the Single-Use Plastic Directive. Even the business sector aims to reduce their environmental impact by making their products plastic free or by using ‘cleaner’ types of plastic, such as bio-based and biodegradable plastics. However, these types of plastics can be misleading for consumers because they often are just as pollutant as regular plastics. So how environmentally friendly are biodegradable plastics?

Green plastics?

Bioplastics can be divided into two categories: the bio-based and biodegradable plastics. Bio-based plastics are often promoted as an eco-friendly material, because they are made of biomass instead of fossil resources. Although they are not petroleum-based and originated from renewable sources, they are plastics nonetheless. Their degradation time in the environment can be just as long as petroleum-based plastics and thus just as polluting. Biodegradable plastics are also branded as an environmentally sound substitute, because they are able to fully degrade over time. That nearly all materials will degrade over time is something that is withheld from consumers. It is usually not specified in what timeframe or under what environmental circumstances bioplastic is able to degrade. In areas where plastic litter is commonly found, on the ground and in water, the environment is not suitable for biodegradation. Most biodegradable plastics can only degrade in a special industrial installation, where temperature, humidity and light are controlled. Even biodegradable plastic materials that are labelled as compostable are not compostable at home, but only at industrial composting installations. Currently, biodegradable (including ‘compostable’ plastics) are often not composted or recycled in the Netherlands, but are treated together with residual waste. Another example is oxo-degradable plastics. Oxo-degradable plastics used to be promoted by manufacturers for their ability to degrade faster than regular plastics. However, these plastics do not actually biodegrade but merely break down into microplastics that remain in the environment. Because of the harmful effects on the environment, the EU has imposed a complete ban on the once praised oxo-degradable plastics.

What about the Leiden University cups?

Leiden University has printed its logo on certain plastic cups that are marked as being biodegradable. In fact, these cups are made of polyactic acid (PLA), a bio-based plastic derived from renewable biomass, such as corn or sugarcane starch. In order for PLA to degrade, it needs to be collected separately and treated in a special industrial composting installation for three weeks. Since the cups are not collected separately, they will end up with the residual waste which is most likely being burned in an incineration facility. Special composting facilities are not available in most municipalities and will therefore not decompose in regular environments. In that case, the appropriate disposal method is by means of incineration. Besides, if PLA ends up in the stream of plastic for recycling, it can even cause problems in the recycling process. The PLA causes a significantly lower quality of the generated material. This makes it unsuitable for many purposes and significantly lowers its commercial price. Since PLA looks exactly the same as regular plastic, PLA could easily end up in the wrong garbage bin. Most consumers do not know in which waste bin it belongs, which can actually differ per municipality. Waste companies currently advise disposing biodegradable plastic in the residual waste bin.

Imposing regulations against greenwashing

Due to the confusion surrounding all these terms, some manufacturers have seized the chance to ‘greenwash’ their products, labelling them as being environmental-friendly. These labels mislead consumers and may trick them into buying products, even though the materials are just as polluting as their regular polymer counterparts. Several experts and organisations are pressing for measures that will lead to clearer definitions. First, biodegradability should be measured in accordance with international scientific standards and specified for different environmental circumstances. Second, certification systems should be set up to create more accurate biodegradability labels, such as ‘marine degradable’ and ‘home compostable’. In this way, internationally harmonised standards for different kinds of plastic could stimulate separate collection, leading to better recycling options.

The European Union shares this ambition to create clarity for consumers. According to Article 8a of the waste and waste packaging directive, specifications of labels or marks for the biodegradability and compostability of plastic bags should have been established by May 2017. The aim was to provide consumers with correct information about the biodegradation and composting properties of such bags. However, it seems that no specifications have been implemented yet and there are no plans to do so in the near future.

Scientific standards key to improving recycling

With the widespread belief that plastic pollution could turn into an environmental crisis - a preventable crisis - the demand for alternatives that are less polluting is rising. Unfortunately, most bioplastics do not reduce pollution as much as advertised, and regrettably this also includes the Leiden University plastic cup. The cups are used as an environmentally sound alternative for plastic, though they hardly contribute to the prevention of plastic pollution. Therefore, standards on biodegradation and composting based on scientific research are urgently needed to phase out the use of those bioplastics that do not prevent pollution. Furthermore, labelling based on these standards is necessary to prevent greenwashing, so consumers can make informed choices for sustainable products. Labelling will also improve separation and recycling of plastics, thus leading to better quality of the recycled materials. Only then can the ‘myth’ of bioplastics be effectively busted.

The Leiden Advocacy Project on Plastic (LAPP) will continue to research the interaction between the natural sciences and policy, including the regulation of plastic as a chemical and waste compound.