In this book, Plastique, le grand emballement [1], INRAE research director and packaging science expert Nathalie Gontard traces back the history of plastic to explain the craze it has generated since its creation, concerns related to its pollution, and the complex problem of its end-of-life.
Plastic appeared in the 1960s following the discovery of polymerization. This process allows the creation of new materials with fantastic properties: lightweight, transparent or colored, resistant, waterproof, inexpensive, plastic is perfectly suited to industrial needs, especially for packaging. It is also very suitable for international trade, as it is not affected by humidity, temperature variations or shocks. Multiple molecules are created, the most widespread being polyethylene and polypropylene. Plastic quickly became synonymous with technological progress and economic development, and displaced traditional materials.
At the time, its harmful effects on the environment and human health were ignored. However, they are immense. This synthetic material is so foreign to the biological functioning of our environment that it takes several centuries to be digested by microorganisms and to reintegrate the carbon cycle. It slowly decomposes into tiny particles that spread in all environments, penetrate deep into an organism and interact with molecules of all kinds. Plastic pollution has thus spread from the depths of the oceans to the smallest raindrops, even passing through our very own bodies.
The benefits of polymers were first called into question in the 1990s. A succession of health crises made people aware of the dangers of plastic. It was discovered that additives, molecules added to polymers to give them certain properties, easily contaminate the substances with which they are in contact and create health risks. An exemplary case is that of Bisphenol A, an endocrine disruptor widely used in baby bottles, cans and cash register receipts. It was banned in France in 2012.
Alongside these health crises, plastic pollution has slowly emerged as a problem in itself. Research efforts have been focused on tackling this issue but currently no solution is fully satisfactory. “Oxodegradable” plastics were first invented. These plastics can decompose very quickly into tiny fragments under the effect of light and other natural phenomena. However, these fragments’ end-of-life was not studied, as biodegradability was not considered a major issue. Following the 1970s oil crisis, industrial actors and politicians were primarily concerned about running out of this now indispensable material. Innovative “bio-based” plastics were getting a lot of attention at the time. Despite the fact that they are as persistent in the environment as their petroleum-based cousins, these plastics were praised for having the same properties. A few years later, the discovery of nanoparticles revived the craze for this ever-evolving material. Augmented plastics are increasingly used in many different fields, for example reducing the weight of airplanes, reinforcing car shells, or slowing down the development of bacteria in baby bottles.
Originally, plastic started being recycled for reasons entirely unrelated to the preservation of the environment. Instead, recycling began out of fear of running out of this material. The challenge was to reuse plastic identically and infinitely. The most widespread technique for recycling is mechanical recycling. It consists in heating the plastic so that the molecules that have been in it evaporate, without modifying the structure of the polymers. However, it has one important limitation: the additives and impurities that have become embedded in the plastic during its use are difficult to remove. As a result, the plastic waste can only be transformed into a material of lower quality than the original. This is “down-cycling” rather than recycling. The only exception is “PET”, which is used a lot for plastic bottles. PET can be recycled a single time without losing its suitability for food contact if virgin PET is added. Some advanced technologies that can infinitely recycle a wide range of polymers do exist, but their environmental benefits have yet to be established and they are too immature to be deployed on a large scale.
Recycling has thus been added to the two other treatments of plastic waste: disposal in landfills and energy recovery. Neither is satisfactory. Disposal in landfills does not exploit the energy or economic value of the waste and generates significant environmental pollution: the waste and the large plastic sheets in which it is buried decompose over time and contaminate the soil. Energy recovery consists either in incinerating the waste, with a residue that has to be buried in turn, or in transforming it into fuel through pyrolysis. In both cases, combustion generates toxic emissions and releases CO2.
Europe and France have a goal of reaching “100% plastic recycling” by 2025. This objective seems highly ambitious considering the current situation in France: about 30% of plastics are buried, 46% are incinerated, 14% are collected for recycling. It is also an incoherent target given the aforementioned limitations of recycling. Of the total plastics collected, 4% are lost along the way, 8% are downcycled and a very low percentage is actually recycled. The plastics that are recycled are mainly PET bottles, which make up less than 2% of the plastics we consume. A significant portion of the collected waste is sent to developing countries, where its fate is uncertain.
Until 2017, China was the main importer of waste. No longer wishing to be the world’s garbage dump, it closed its doors that year, with other countries in Asia following suite. While the general public discovered that its waste often ended up abandoned on the other side of the world, industrial actors and politicians had to urgently find new outlets. New industrial and marketing strategies were developed: products containing “recycled” plastic are now presented as “green”; the low carbon footprint of plastic is emphasized, ignoring its other environmental impacts. The idea of “plastic neutrality” has even emerged in the public debate. Companies could continue to use virgin plastic depending on their recycling funding, like the carbon market. However, Nathalie Gontard reminds us that recycling does not allow us to eliminate plastic waste, or to go without virgin plastics. Another marketing opportunity is the “bio” logos of bio sourced plastics, boasting their natural origin but ignoring their lack of biodegradability.
Nathalie Gontard thus criticizes our “plasticized” mind. Convinced that polymers are indispensable to us, we only consider the solution through innovations in the world of plastics. Opposite to European and French policies, which base their entire environmental strategy on recycling, she recommends treating the problem at its source: by reducing our overconsumption of plastic. Recycling is part of the solution, but it cannot distract us from the necessary profound changes that need to be made in our production and consumption patterns.
Lise Peragin, Research Fellow, Recycled raw materials: Which treatments, which uses? Impacts on resources and carbon balance.
Gontart, Nathalie with Seingier, Hélène (2020), Plastique, le grand emballement [1] Edition Stock, 220pp.