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In the lungs, stools or blood, traces of microplastics in the human body are tracked to better identify their potential threat to health, which is still poorly understood.
Every day, humans ingest, inhale, have their skin in contact with plastic microparticles (less than 5 millimeters). They are in the air, in water, food, packaging, synthetic textiles, but also tires or cosmetics.
Presence in the human body
In recent years, in humans, microplastics have been detected in the lungs, liver, placenta and, ultimately, blood. This is the conclusion of a Dutch study published in 2022 in the journal Environment International. If scientists call for caution in view of its small sample, this presence of microplastics questions their transport into the organs through the blood system. For the time being, the data remains incomplete as to the real health effects of exposure to microplastics, a complex cocktail of polymers and chemical additives, to which various contaminants can be added by a “Trojan horse” effect.
“For the past ten years, there has been more and more research” on the impact of microplastics even if, “As with global warming, we started late because these are insidious changes”toxicologist Xavier Coumoul, pilot of the Inserm Metatox team, told AFP.
“We do not know if our level of exposure will induce chronic or acute diseases in the long term, (but) we can legitimately ask ourselves the question”, explains Mr. Coumoul. Indeed, research in animals or in vitro has detected effects at the cellular level (increase in inflammation, oxidative stress, cell death, etc.).“On human and mouse lung tissue, we observed a development inhibiting effect, after placing plastic fibers inside organoids – kinds of mini-lungs from cells”, told AFP Barbro Melgert, from the University of Groningen (Netherlands).
The effect seemed to come from “of something chemical leaking from the plastic. But we don’t know what product was involved – it’s very difficult to determine, especially at low amounts.”added this respiratory and microplastics expert.
“tipping point”
The role of shape, size, type of plastic and additive remains poorly understood. Lately, researchers have tried to determine the movement of microplastics of different shapes and sizes, with slow or fast respirations. They more or less tend to accumulate in the nasal cavity or the back of the throat, according to their modeling study, which appeared last Tuesday in Physics of Fluid.
Alongside the health effects, there is also great uncertainty about the exact level of exposure to microplastics. “For ordinary people, we don’t really know how many microplastics we take in. There aren’t many studies and we need longer studies”according to Barbro Melgert.
A shock report by the NGO WWF estimated in 2019 that a human being ingests and inhales up to 5 grams of plastic per week, the equivalent of a credit card. Its results and its methodology have been disputed, and other works have certainly evoked much lower estimates, but some researchers like Ms. Melgert still fear that microplastics constitute a “time bomb”. As “we continue to produce plastic massively”the Dutch researcher warns of a potential “tipping point” for human exposure.
However, the fight against plastic pollution took a step forward in early June in Paris: after five “laborious” days, 175 countries decided to establish a “first version” of a future treaty between now and their next negotiations, in November in Kenya. And, already, everyone would do better to limit their exposure to microplastics, judge the experts questioned, by “precautionary principle”. They suggest ventilating your home as much as possible, not eating from plastic containers, avoiding synthetic textiles, etc. Better to take precautions because “for pesticides or other molecules, it sometimes took a long time to identify the long-term risks for humans”warns Mr. Coumoul.