In 2022, a team led by Marja H. Lamoree of the Free University of Amsterdam published some disturbing results. Using a new analytical method on blood samples from 22 volunteers, they found that 77% had plastic particles. If these particles are transported by cells of the immune system, the researchers said, we should ask ourselves if this can affect the regulation of the body’s defenses or the predisposition to immunological diseases. In Italy, in 2021, a team led by Antonio Ragusa, director of Gynecology and Obstetrics at the Fatebenefratelli Hospital in Rome, had detected microplastics for the first time in the placenta of pregnant women, although they could not find out if they had reached the babies. A year later, they also found plastic particles in the milk of three out of four mothers who participated in another study on the presence of these substances.
“Until recently, it was believed that microplastics entered our body and left. It was thought that a particle could cause inflammation in the digestive tract as it passed, but not that it could cross cellular barriers and accumulate in organs. Now we know that this does happen,” explains Ana Isabel Cañas, director of the National Center for Environmental Health, in Majadahonda (Madrid). Although plastic has been everywhere for many decades, concern had focused on the almost eternal waste that accumulates in the sea or in the countryside. In recent years, the development of new microscopy and spectroscopy techniques has made it possible to see how tiny plastic particles, some smaller than bacteria, have turned our organisms into landfills.
With new detection methods, alarming results are piling up. In a recent study published in the journal PNASresearchers at Columbia University (USA) discovered that around a quarter of a million of these plastic pieces could be found in each one-liter plastic bottle. These materials can be broken down into smaller and smaller parts, allowing them to also be inhaled, as well as ingested with food or drink.
“Considering that our lungs filter about 12,000 liters of air a day, we are continually exposed to different micro and nanoplastics, their associated additives and other contaminants and microorganisms that make inhalation a route of special concern,” write researchers from the Institute of Germans Trias i Pujol Research, in Badalona, and the Autonomous University of Barcelona. It is likely that this is the main transport route for nanoplastics that are released by clothing or rubber from tires when they rub against the asphalt; and those plastics can be especially dangerous because they were not designed for food use like bottles.
José Domínguez, leader of the Germans Trias i Pujol group, explains that there is evidence in cellular and animal models that nanoplastics accumulate and have effects on the inflammatory response and produce cellular toxicity, “something that makes it plausible that they may cause problems in the long run.” of health”. But he recognizes that “in humans there is still no such certainty.” His team works to understand the effect of these ubiquitous substances on their interaction with microbes that cause respiratory diseases. “Plastics can introduce microorganisms into the body, but sometimes they are so small that it is the plastics that are transported by the microorganisms,” says Domínguez. Plastic can cause inflammation, or attenuate the immune response, so that bacteria like Staphylococcus aureus produce more virulent infections. To this interaction we must add those produced by traffic smoke to begin to understand the effect of fundamental elements of our lifestyle on health.
Plastics that reach the market and come into contact with food are studied to be non-toxic, but aging or the effect of ultraviolet light from the sun degrades the material and changes its characteristics. From there, unknowns arise about their new role, which increase when microplastics interact with other elements in the environment. “That can be toxic because it goes beyond quality controls,” says Jorge Bernardino de la Serna, from Imperial College London. As the researcher explains, it was assumed that safe microplastics could enter the body, but it was expected that after ingesting them, they would be expelled. “When it was seen that there were pieces of plastic in the blood bags, we all started to worry,” he says.
Nanoparticles that transport toxins
The researcher explains that pure plastics are so well made and are so little harmful that the cells swallow them as if they were just another food. As they are not biodegradable, the plastic particles are integrated into the cell which, when it divides, distributes the plastic among the new cells as it does with the rest of its constituents. “This is worrying, because, if it is not eliminated, it can pass into the blood and from there go to other organs or lymph nodes, affecting the immune system, and it can even cross the blood-brain barrier that protects the brain,” explains Bernardino de the Serna. There are scientists who consider this mechanism as a possible explanation for some mental or neurological diseases, perhaps not due to the effect of plastic, but rather due to other toxic elements or endocrine disruptors, which can travel attached to these nanoparticles. In studies in mice, it has been observed that microplastics can reduce sperm quality; something that could explain, at least in part, the decline observed in humans in the last half century.
Ana Isabel Cañas points out that “there is still a lack of analytical instrumentation to quantify and identify each type of plastic, because there are an infinite number and the toxicity can be different.” And she warns of the difficulty of identifying the damage that can be caused by a ubiquitous substance that, in the real world, is not usually alone. “It is easier to address the risks of a simple compound (such as bisphenol A) than of a particle that, in addition to the main plastic, contains additives that have been added to improve flexibility, change color or make it water resistant, because they do not “You know what to associate toxicity with,” says the director of the CNSA. Furthermore, to advance in this new field of research, methods must be found to analyze the effects of plastics in real conditions and not only the pure plastics that are usually used in research.
Scientists insist that, at the moment, the impact of micro- and nanoplastics on human health is not known. Techniques are now beginning to be developed to accurately evaluate the quantities of these particles and their typology, something about which until now there was mainly only speculation. To try to understand the health impact of these particles, the European Union launched the CUSP cluster in 2021, made up of five research consortia: AURORA, IMPTOX, Plastic Heal, PlasticsFatE, and POLYRISK. While they begin to offer results, there are simple recommendations, such as replacing plastic bottles with glass ones, but replacing this practical and ubiquitous material will be complicated. In 1950, two million tons of plastic were manufactured in the world, in 2021 this number reached 461 million and is estimated to reach 590 million tons in 2050. Of that amount, only 9% is recycled. Even if plastic production were reduced, particles from the tons released into the environment will continue to fragment and travel through air or water around the world for centuries.