Microplastics in drinking water: what danger for health?

Microplastics, increasingly present in our environment, can be ingested and reach different organs of the body, with health consequences that are still unknown. We take stock with Professor Jean Demarquoy who publishes Microplastics – Our health in danger.

Emblem of modern society, plastic shapes our entire environment. Just look at the objects lying around on your desk: a plastic ruler, a plastic pen, a pack of tissues with plastic packaging, a plastic lamp… Plastics are everywhere in our homes, our clothes, and our packaging, including food.

Microplastic pollution in the environment

Most of the plastic produced is intended for packaging with 40% of plastic used only once before being thrown away, according to National Geographic (1). As it is very poorly recycled, plastic accumulates in the environment, including in the form of very small particles, which are found even in seemingly preserved natural areas.

“I already knew, like many, the existence of this vast area of the Pacific that some call the “seventh continent”, where plastic waste accumulates, explains Jean Demarquoy. But it was while consulting, one day, a series of photographs taken from a surveillance plane that I really understood the phenomenon. Fragments could be seen floating on the surface, spread out for kilometers. An ocean of waste.”

Over time, plastic never really goes away. Under the action of water, wind and light, it fragments, divides and decomposes into a multitude of increasingly smaller particles: microplastics, particles between 1 and 1,000 micrometers (μm) and nanoplastics, for those whose size is less than 1 μm.

Many of these particles are found in the oceans, but not only that. “The floors agricultural products, in particular those amended with sludge from wastewater treatment plants, have become real reservoirs of microplasticssaid Jean Demarquoy. In Europe, it is estimated that 63,000 to 430,000 tonnes of microplastics are spread each year on agricultural land via sewage sludge. On land, in the ground, at sea, in the seabed, or in the air, microplastics are everywhere!

Microplastics in food

Given the omnipresence of microplastics in the environment, animals can ingest them and enter the food chain. “Studies have detected microplastics in fish such as tuna and mackerel as well as seafood, raising the question of long-term dietary risk.”

But the risk also concerns the water we drink and health authorities are interested in our exposure through drinking water. In 2019, the World Health Organization (WHO) published an alarming summary on this subject (2).

Microplastics in drinking water

The WHO analyzed around fifty studies, the most reliable on the subject, to determine the levels of pollution in drinking water and the potential risks of the presence of microplastics for human health. According to the WHO, risk comes in three forms:

physical: linked to the plastic particle as such;
chemical: migration of molecules in the environment;
biofilm: pathogenic microorganisms attached to plastic particles.

Results : microplastics larger than 150 µm do not appear to be absorbed by the digestive system, while absorption of even smaller molecules is expected to be “limited”. On the other hand, the fate of nanoparticles is still poorly known, but it seems that their absorption is greater.

Microplastics are present everywhere, including in the water we drink.

“It is urgent to know more about the health consequences of microplastics, because they are present everywhere, including in the water we drink” said Dr Maria Neira, Director of the WHO Department of Public Health, Environment and Social Determinants of Health. “Based on the limited information we have, microplastics in drinking water do not appear to pose health risks, at least at current levels. But we need to look deeper into the matter. »

Tap water or bottled water?

Tap water may contain microplastics, but there are even more in bottles! “Several studies have shown that some brands of bottled water contain up to 10,000 plastic particles per liter, on average twice as much as tap water,” said Jean Demarquoy. This is explained by the particles that come off the packaging, but also by the production processes of the water bottles. You might think that glass water bottles are safer because they prevent the direct release of plastic from the container. “However, they are not completely free of microplastics: caps, seals or equipment used in the production line can contribute to residual contamination.”

Read: Stainless steel, plastic, aluminum: which bottle to choose?

What are the health dangers of microplastics?

Given their small size, micro- and nanoplastics can cross natural barriers, enter living organisms, by ingestion or inhalation, and interact with cells. “Certain laboratory studies have, in this regard, demonstrated that nanoplastics can penetrate plant and animal cells,” said Jean Demarquoy.

Microplastics enter our lungs and enter the bloodstream. But what happens to them next? In which organs will they be housed?

The accumulation of microplastics in the human body

American researchers looked for micro- and nanoplastic particles in the tissues of deceased people: in the brain, liver and kidneys (3). They found that polyethylene particles were most frequent in these tissues, but also that the brain contained more of them than the liver or kidney. They also found that plastic concentrations increased over time in liver and brain samples and thateven greater accumulation was observed in the brains of people who died with a diagnosis of dementia.

For the authors of this research, “Environmental concentrations of anthropogenic microplastics and nanoplastics, polymer-based particles ranging in diameter from 500 µm to 1 nm, have increased exponentially over the past fifty years.” It is therefore essential to limit our exposure and protect our brain.

Pollution of concern for human health

Exposure to microplastics still raises many questions about health that research has yet to explore. But we already know that microplastics impact animals and cells. “Once inhaled, these microplastics can cause irritation, chronic inflammation or oxidative stress”said Jean Demarquoy.

In addition, at the nanometric scale, their surface can be used to adsorb (fix) toxic compounds, such as endocrine disruptors, eternal pollutants, etc. In water, microorganisms such as bacteria can also develop on these “little rafts” and form biofilms. Consequences: transport of potentially dangerous bacteria (pathogens), but also an increase in antibiotic resistance phenomena.

Read: Microplastics promote antibiotic resistance

And the smaller the particle, the greater the surface area for asorbing contaminants: “each fragment of microplastic, by degrading and fragmenting into smaller and smaller particles, sees its total surface area increase, said Jean Demarquoy.
This fragmentation multiplies the interfaces available for the adsorption of contaminants, such as heavy metals, persistent organic pollutants or microorganisms.” So many problematic compounds for the body that risk entering our bodies…

Plastics particularly dangerous for the health of certain populations

Certain populations are particularly vulnerable:

the childrenbecause their development could be disrupted by endocrine disruptors carried by microplastics. Due to their small weight, young people are exposed to proportionally higher doses than adults;
pregnant womenbecause microplastics can cross the placental barrier;
the workers professionally exposed to plastics, particularly in industry
textile, recycling, plastics processing or the manufacture of paints and varnishes. “In these environments, concentrations of microfibers or plastic dust are well
superior to those encountered in daily life.

In practice: how to limit plastics in the environment

Even though they seem very practical, many single-use plastic products have been banned, such as disposable tableware (4). Good news of course, but couldn’t we go a little further? Certain initiatives to adopt in everyday life could help limit pollution caused by plastic, such as:

purchase repairable/repairable and recyclable/recycled products;
favor bulk foods: groceries, cheese, cleaning products, fruits and vegetables;
avoid processed products that are very often overpackaged;
favor homemade products, particularly for cosmetic products: deodorant, toothpaste, solid shampoo, etc.