Alternative plastics: more harm than good?

It’s commonly understood that plastic packaging can’t be banned without suitable alternatives for manufacturers to switch to. The problem is, while there are plenty of alternatives none of them can provide a straightforward swap for many of the things we use plastic for.

A new study recently says as much.

Plastic makes modern living comfortable. However, too heavy on a reliance on this versatile material has come at a cost – especially to the environment. According to UNEP, the UN Environmental Programme, approximately 85 per cent of which ends up in landfills or as unregulated waste.

In recent years, packaging made of conventional plastics has been increasingly replaced by materials believed to be more sustainable. The growing sense of environmental responsibility among companies has triggered a shift towards alternative materials that are perceived as more sustainable than plastics. Yet, a question remains: are they really more sustainable?

A new study by the AWARE (Assessment on WAste and REsources) research group of the Politecnico di Milano, Italy, examines the true sustainability of alternative materials. The research analysed 53 peer-reviewed life cycle assessment (LCA) studies published between 2019 and 2023. The aim was to gain an in-depth understanding of the environmental impact of packaging, focusing on the comparison between plastics and alternative materials.

The literature showed that consumer perceptions often differ from LCA findings and revealed that conventional plastics are not the least environmentally friendly choice. Bioplastics typically show benefits only in the climate change and the fossil resource depletion impact categories. The heavy weight of glass turns out to affect its environmental performances with respect to the light plastics, with reuse being an essential strategy to lower the burdens.

The comparison between plastics and metals is more balanced, leaning more towards plastics for food packaging. Similarly, paper resulted often preferable than plastics. Finally, for the other materials (ie wood and textiles), the picture is variable. To be competitive with plastics, the alternative materials require improvements like the optimisation of their production processes, their reuse and enhanced end-of-life options. At the same time, recycled polymers could boost the eco-performance of virgin plastics.

Especially bioplastics are emerging as a viable alternative in terms of climate change and fossil resource depletion. They are made from renewable resources and/or are biodegradable. However, other environmental impact categories show some drawbacks, indicating that there is no one-size-fits-all solution.

In addition, the use of glass, although seemingly more sustainable, poses challenges related to its weight, which affects its performance not only in production but also in transport. Although reusing glass is an environmental improvement, it must be done under specific conditions to make reused glass more advantageous than conventional plastics.

In the case of metals such as aluminium, the comparison with plastics is more balanced, particularly in the beverage sector. Nevertheless, even here there are opportunities for improvement, such as focusing on reuse and limiting the transport distances and environmental impacts associated with the reprocessing and washing of packaging.

The life cycle assessment analysis also identified areas for improvement for all the materials studied. Glass and metals could benefit from increased re-use, while bioplastics require optimisation of production processes and end-of-life management, the researchers wrote.

It is somewhat surprising that, according to the scientists, conventional plastics are not always the least environmentally friendly choice.
The pros and cons of each material need to be weighed up when working out a balance between the most functional and the most sustainable option.

Working out the impact of a particular material on the planet is complex, with numerous factors having a part to play: weight, distance travelled, recyclability, energy utilisation and the processes.

Plastic alternatives can cause environmental problems too.

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