American researchers found, when analyzing around sixty placenta samples, that each had been contaminated by microplastics, reports a study recently published by the journal Toxicological Sciences.
The samples came from a biobank established between 2011 and 2015, demonstrating that human exposure to even smaller micro- and even nanoplastics, while currently receiving a lot of attention, is not new.
“We can expect that there will be other studies that will come out with more recent tissues,” said Professor Cathy Vaillancourt, a specialist in the implication of environmental factors on the neuroendocrinology of the human placenta at the National Institute of Scientific Research (INRS).
“But to me, what it demonstrates is that (the placenta) needs to be studied. If we are already exposed in utero to these agents, it is doubly important to make regulations based on, and to have guidelines that are for, pregnant people. »
American researchers found concentrations ranging from 6.5 to 790 micrograms of microplastics per gram of fabric. They mainly detected polyethylene (which is used in the manufacture of plastic bags and bottles), PVC and nylon in their samples.
Micro and nanoplastic particles come from the breakdown of larger plastic items. Microplastics range in size from one micrometer (one millionth of a meter) to around five millimeters. We measure the size of nanoplastics in billionths of a meter. For comparison, the circumference of a human hair is approximately 70 micrometers.
Nanoplastic particles are so tiny that they can enter the bloodstream (for example, crossing the intestinal barrier) and travel directly to organs.
The impact of these particles on human health is still poorly understood, but they possibly interfere with the functioning of certain organs (including the brain) and that of the reproductive system. They could also have carcinogenic properties, be a source of oxidative stress and imitate the action of certain hormones (so-called endocrine disruptors). Other studies implicate them in inflammatory bowel diseases.
“What we know with animal models is that they (plastics) alter the structure and therefore the functions of the placenta,” underlined M.me Vaillancourt. And any alteration, any defect or any modification in placental functioning is an indicator that something happened during pregnancy, and this can have short, medium and long-term impacts on the baby’s health, but also on the mother. »
The placenta exists to protect both the baby and the mother, she continues, “but at a given moment, it exceeds this capacity, and we know that alterations in the placenta or in its functioning will be associated with development problems.
“We often tend to think that the placenta is a barrier […] of safety, then that what does not pass from the mother to the baby is not dangerous, but it is a myth because what affects the placenta will affect the baby, even if it does not reach the baby. warned Mme Vaillancourt.
A worrying problem
But the problem of nanoplastics is even more worrying and more complex than it seems at first glance, warns Professor Daniel Cyr, holder of the Canada Research Chair in Reproductive Toxicology at INRS.
Microplastics, he points out, can cause inflammation, and inflammation will have the effect of “opening” cellular barriers that would otherwise remain closed.
“And it’s not just the type or size of the plastic,” said Professor Cyr. There are more and more studies (which show) that there are a bunch of other molecules that can bind to plastics, like pollutants, pesticides, hydrocarbons, metals… We didn’t have realized that all these products can be transported by microplastics to certain organs. »
Microplastics, he says, allow these unwanted substances to “bypass” the body’s defense systems to infiltrate every nook and cranny.
The question that then arises, obviously, is whether and how it is possible to minimize our exposure to these particles.
“We have been telling people for several years to be careful, not to reuse disposable plastics,” recalled Professor Cyr. We use less and less plastics, we release less and less into the environment, but it will take a grandiose effort because (plastics are) really the new dioxin of the 2000s. Back in the day we were talking about As dioxin is spread everywhere, nanoplastics are everywhere on the planet, and the only way to stop this is to stop using them. »