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PARIS: From the bottom of the oceans to the tops of mountains, microplastics are everywhere in the environment, but not only. They also make their way into the human body, from the lungs to the placenta, a disturbing contamination even if its impact is uncertain.

Floating bottles, a turtle suffocated by a bag, piles of waste in the middle of the Pacific… For years, the images of the pollution of the oceans by the hundreds of millions of tons of plastic produced each year have been difficult to ignore.

But their degradation into smaller and smaller particles which pollute the water and the air in quantity has been more recently proven.

“We did not imagine ten years ago that there could be so many small microplastics invisible to the naked eye and that they were everywhere around us”, comments Jean-François Ghiglione, researcher at the Oceanology Laboratory bacteria from Banyuls-sur-mer in France. “And we could not yet envisage finding them in the human body”.

This is now done, with a proliferation of scientific studies showing the presence of these microplastics in certain human organs.

Like the lungs. Not so surprising that we breathe these particles present in the air, in particular microfibers from synthetic clothing.

But “we were surprised to find microplastics so deep in the lungs,” Laura Sadofsky, from the Hull York School of Medicine in the UK, told AFP. His team notably identified polypropylene and PET (polyethylene terephthalate) in these fabrics.

In March, another study reported, for the first time, traces of PET in the blood. Given the small sample of volunteers, some scientists call for caution on the conclusions to be drawn, but this presence raises questions about the ability of the blood system to then distribute these particles to all organs.

Without their journey inside the body being known at this stage, microplastics have also been found in other organs: “Lungs, spleen, kidneys, and even the placenta”, launches Jean-François Ghiglione.

– “Precautionary principle” –

In 2021, researchers had found it in maternal and fetal placental tissue, expressing their “great concern” for the potential consequences of this foreign presence on the development of the fetus.

However, concern does not rhyme with proof of danger. “If you ask a scientist if there is a negative impact, he or she will answer + I don’t know +”, comments Bart Koelmans, from the Dutch University of Wageningen.

But “it’s potentially a big problem,” he said. So “the other question is about policies: what should we do if there is concern in society and no scientific proof yet”.

The avenues of study are not lacking. He evokes the hypothesis that this intrusion of microplastics – which although recently detected is not new – is for example responsible for certain syndromes weakening human organisms.

An intrusion that goes through breathing but also through what we eat and drink.

In 2019, a shock report by the NGO WWF estimated that a human being ingests and inhales up to 5 grams of plastic per week, the equivalent of a credit card.

Results and a methodology disputed by scientists like Bart Koelmans whose calculations conclude rather at an average of one grain of salt per week.

“Over a lifetime, a grain of salt a week is already something,” he comments.

While health studies on humans have yet to be developed, toxicity in certain animals reinforces concerns.

“Small microplastics invisible to the naked eye have deleterious effects on all the animals that we have studied in the marine environment or on land”, assures Jean-François Ghiglione. The fault of the chemical additives they contain (dyes, plasticizers, stabilizers, flame retardants…) “which can have impacts on growth, metabolism, blood sugar, blood pressure, sexuality…”.

So, “there is a precautionary principle to take”, insists the researcher.

As a consumer, “one can simply limit the purchase of packaged products”, in particular plastic bottles, he suggests.

But “people can’t stop breathing”, emphasizes Bart Koelmans. “Even if you change your eating habits, you will inhale them: they are everywhere”.

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