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From the lungs to the kidneys and even the blood, microplastics have been found in almost every part of the human body. If scientists have no certainty so far about their impacts on health, several specialists are sounding the alarm.
Plastic microparticles (less than 5 millimeters) have been detected in the air, in water, in food, packaging, synthetic textiles, tires or cosmetics. Every day, humans ingest them, inhale them or come into skin contact with them.
“The man of 2024 contains plastics in almost every organ of his body (…) and it will probably be even worse for the children who will be born in 2040“, declared Fabienne Lagarde, researcher at the Institute of Molecules and Materials in Le Mans, during a recent hearing by French parliamentarians.
In recent years, scientists have found them in the lungs, heart, liver, kidneys, and even in the placenta and blood.
And correlations between microplastics, even nanoplastics (1,000 times smaller), and effects on health have been pointed out in various studies.
Among the latest, a study published in March in the New England Journal of Medicine shows an association between the accumulation of these particles in blood vessels with an increased risk of heart attack, stroke, and even death, in some people with atherosclerosis, a disease affecting the arteries.
Unknowns and dangers
“Research on microplastics is increasing and identifying very worrying health effects. A recent meta-analysis of 2,000 animal studies, conducted with colleagues, showed that microplastics appear to affect fertility, be linked to an increased risk of cancer or harm respiratory health“, Professor Tracey Woodruff of the University of California told AFP.
For this director of a program on reproductive and environmental health, these data, added to “the discovery of microplastics in many parts of the body, including the brain, testicles, and even the fetus via the placenta“, constitute a “alarm signal”.
To date, a cause and effect relationship has not been able to be established with human exposure to these complex cocktails of polymers and chemical additives, to which contaminants such as bacteria or even viruses can be added, for example. a “Trojan horse” effect.
Most often, the studies of concern have been carried out in the laboratory, sometimes on human cells, or on animal models.
Some observers see this as a limit. But the animal studies reviewed bear “on biological systems very similar to those of humans“, And “animal data has been used for decades to identify carcinogenic or reprotoxic substances“, objects Professor Woodruff.
On the impact of microplastics, several unknowns remain on the role of the shape, size, type of plastic or additive.
“Precautionary principle”
Of more than 16,000 chemical substances used or found in marketed plastics, more than a quarter nevertheless present known risks, according to a “coalition of scientists for an effective plastics treaty“.
This includes “infertility, obesity and non-communicable pathologies such as diabetes, cardiovascular diseases, and many cancers“, details a note they published this year.
The level of exposure to microplastics remains uncertain.
A shocking report from the NGO WWF estimated, in 2019, that humans ingest and inhale up to 5 grams of plastic per week, the equivalent of a credit card. The results and methodology were contested, and various scientific works subsequently cited lower estimates, or very variable ones depending on the region of the world.
Research on microplastics and health, started in the early 2000s, must continue, but is already encouraging action, according to several experts.
“Despite the youth of the topic and the identified limits, dangers linked to oral exposure and inhalation are there.“, underlined Muriel Mercier-Bonin, research director at the National Research Institute for Agriculture, Food and the Environment, during the hearing in the French Parliament.
Governments, regulators and manufacturers have a key role to play, because “the most important thing is to strengthen measures to limit plastic production and pollution“, according to Tracey Woodruff.
Individually, reducing your exposure is a “precautionary principle“, for several specialists.
In their advice: avoid plastic bottles, do not heat food in plastic, favor clothing made from natural materials and ventilate your interior.