Sophie Chapelle: When we think of plastic pollution, we visualize the seas of plastic described as the “seventh continent”. Why is there more danger in plastic that we cannot see?

Nathalie Gontard: The danger is very often equated with plastic waste large enough to be seen. Their consequences are not negligible – in quantity, they dry out the soil and suffocate species that ingest them. But plastic becomes truly dangerous when it is no longer visible, that is to say when it is fragmented into micro and nano-plastics. It then multiplies its interaction and nuisance properties. It has the capacity to transform and absorb essentially hydrophobic molecules, i.e. all pollutants (pesticides, etc.) present in the environment.

Micro and nano-plastics can transport these molecules – through water, air and land – and enter all the organs of living beings, passing biological barriers. We find them assimilated in the pancreas of shrimp, our blood, our lungs, our liver... everywhere!

However, no living being has the biological tools to digest this plastic, to degrade it completely. The result is an accumulation of foreign bodies which leads to biological, metabolic, etc. dysfunctions.

Is this wave of micro and nano-plastics ahead of us?

We have accumulated nine billion tons of plastics on Earth since the 1950s, some of which have already degraded into micro and nano-plastics but the vast majority of which are in the process of degrading, notably in our landfills, but not only that.

Because it is not only single-use plastics that pose a problem, but also those with long-term use, in construction or clothing for example. From the moment they are produced, plastics begin to wear out, degrade and produce harmful micro- and nano-plastics. Micro-plastics in Lake Geneva [50 tonnes accumulate there each year, editor's note] come from synthetic fiber clothing still in use and emitted during washing.

The micro plastics deep in the Arctic ice come from the wear and tear of buildings, insulated with plastics and still in use. Microplastics in the air mainly come from the wear and tear of tires and the roads we use. Plastic pollution is primarily that which we do not see and emitted during use.

The great wave of micro- and nano-plastics is coming. We talk about a “time bomb”. When we produce 1 kg of plastic today, it is future generations who will have to deal with all the micro and nano-plastics that will result.

To what extent has plastic invaded the agriculture and food sector?

Of all the plastics we use, 40% comes from the manufacturing, transport and packaging of our food, therefore agriculture and the agri-food industry. In this sector, the uses of plastic are sometimes very short, with a kind of excess in its use. We have come to the point of consuming food packaged in plastic when we absolutely don't need it! One of the objectives of the anti-waste law for a circular economy (in force since 2022) is precisely to eliminate all this unnecessary packaging, in particular plastic packaging for fresh fruit and vegetables. But industrial lobbies are seeking to delay the implementation of these measures.

What is your view on so-called biodegradable plastic mulch films developed since the 2000s, particularly in vegetable crops and corn?

In agriculture, as in all other areas, new technologies are being developed with a lot of plastic. For example, we use plastics to be placed on the ground to limit the use of pesticides or watering, we cultivate in greenhouses to increase productivity... They are presented as ecological transition technologies. This is true to the extent that they reduce our carbon footprint.

On the other hand, they increase our plastic footprint – that is to say its capacity to last for thousands of years in the form of micro and nano-plastic. The plastic footprint is not taken into account in life cycle analyses. This is why certain strategies are entirely based on recycling, even though plastic recycling does not exist!

Can plastic be biodegradable?

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