Plastic everywhere, health nowhere, warn the CNRS and INRAE

It is, unfortunately, not alarmist to state that the study published jointly on Friday, May 23, by the CNRS (National Center for Scientific Research) and the INRAE ​​(National Institute for Agricultural and Environmental Research) is particularly worrying.

Based on a broad review of 4,500 scientific publications by a group of 30 French and European experts, it shows that plastic pollution is everywhere, from the air we breathe to the heart of our cells, including the soils that are supposed to feed us, with harmful consequences for the entire chain of life – of which humans are the final link. It also shows that it will be very difficult, if not impossible, to get rid of this universal contamination, and that current solutions to reduce it are ineffective.

The basis for these findings is, however, limited, since the study involved studying plastics used in the agricultural and food sectors, which represent only 20% of the 6.4 million tonnes of these materials consumed in France. Of these 1.3 million tonnes, 91% are used for food and beverage packaging and 9% are used for agricultural purposes. In other words, supermarkets sell us primarily plastic, including in the food aisles: this is hardly a surprise.

What is a little more surprising is that, when we look upstream at agricultural uses, we discover that the biggest consumer of plastic is the livestock sector (73%), essentially for the conservation of fodder, far ahead of artificial mulches or crops under cover used in market gardening and horticulture.

The researchers also note that the effectiveness of these agricultural uses is little studied, and therefore little established. Their massive adoption is due above all to their promotion by the petrochemical industry, which has been looking for new outlets since the end of the Second World War . Downstream, plastic is used to preserve and transport but above all to "promote food products through design and labeling" , write the authors, who do not hesitate to conclude that "it is corporate strategies that play a key role in the increase in the use of plastics rather than consumer demand" .

After use comes the waste phase. And here too, the news isn't good. Due to increasingly complex and poorly understood chemical structures, industrial secrecy, and a lack of research, plastics are complicated to manage. And so-called "bio-sourced" plastics (obtained from biomass), often presented as an alternative, currently represent only 1.5% of European production. Furthermore, the researchers observe, the search for properties equivalent to those of petroleum-based plastics, which they are supposed to replace, makes their structure just as complex, when it doesn't result in the integration of petroleum-based substances.

The result: recycling is far from delivering the expected results. Quantitatively, the inefficiency of sorting and collection systems is reflected in volumes: on a European scale, barely more than a third (35%) of plastics is sent for recycling and 42% is incinerated (33% in France). The rest continues to go to landfill (64% worldwide).

But even recycling isn't ideal : the chemical complexity of plastics makes them difficult to recycle—or, as in the case of bio-based materials, requires "the addition of additives or even new plastics" to maintain their functional properties. They're also hardly biodegradable, except in specific industrial processes.

However, all of them end up being fractionable, and this is not their least fault: macroplastics (more than 5 millimeters), microplastics (between 5 mm and 1 micrometer), nanoplastics (less than 1 µm) all end up becoming "a direct source of contamination of ecosystems" , and in colossal proportions. The first victims: soils, whose contamination "is probably greater than the entirety of that of the oceans" , the study warns. "All types of soil, even desert soils, are contaminated by microplastics" which are transported there by all means, including by air, and "agricultural soils in particular are affected" .

These microplastics are present at levels "ranging from 100 to 10,000 particles per kg of soil in the first meter of depth." They "reduce soil microbial biodiversity," vital for their fertility... and our subsistence, and "contaminate flora and fauna directly via the environment or by transfer along the food chain." They also serve as a "Trojan horse": as they spread, they transport and then release into the environment other pollutants such as heavy metals, pesticides, PCBs, antibiotics, and even potentially pathogenic microbial agents.

At the end of the chain, plastics are found in all the organs of living beings, including humans: lungs, digestive system, placenta, and in fluids – blood, but also breast milk. In plants, they degrade vital processes such as photosynthesis or the ability to feed in soils – themselves already impoverished, as we have seen.

Special case: due to their size, nanoplastics have the ability to penetrate into cells, where they "alter their energy metabolism" . Clinical or preclinical studies show that their presence in the heart of tissues induces "pathologies of the reproductive system, inflammation (colon) and fibrosis (liver, kidney, lung, heart)" , as well as "neurological effects" from 6.5 nanograms per kg of body mass per day.

The joint study by the CNRS and INRAE ​​finally highlights the inadequacy of European regulations on these materials: of the 16,000 chemical substances included in their composition, 25% present a known danger and only... 6% are regulated.

Furthermore, this regulation focuses too much on the downstream side, i.e. waste management, and insufficiently on the upstream side: waste production and limiting its uses. This is one of the effects, highlighted by one of the authors during the presentation of the study, of "the influence of petrochemical industry lobbying on regulations." This influence also results in favoring recycling, with its limited effects, over limiting uses, the only long-term solution.

French MPs are preparing to vote on Monday, May 26, on the Duplomb Law, which contains a number of measures likely to deliver the final blow to our plastic-choked agricultural soils. They will do so under threat from some farmers who, for their part, are observing structural yield declines without understanding that resorting to ever-increasing petrochemical inputs will only make matters worse. Both parties would do well to read this study. Or at least its summary.