Plastic pollution spreads throughout practically the entire planet and some of its smaller forms (microplastics and nanoplastics) end up entering the food chain. In addition to contaminated food or water, plastics can also reach the human body through consumer products to which they have been intentionally added (cosmetics, glitter, pharmaceuticals...).
The presence of small fragments of these polymers in the human body is related to various health disorders, although there are still few studies on the matter.
A scientific study led by experts from Duke University (Durham, United States) now provides new data on the possible relationship between the accumulation of nanoplastics and serious brain disorders, such as Parkinson's disease and other mental illnesses. The results of this work, carried out with laboratory models, have been published in the journal Science Advances (November 17).
The authors detail that nanoplastics interact with a protein found naturally in the brain, causing mutations of the same type as those detected in serious diseases. These findings "create a basis for a new area of research, driven by the timely impact of environmental factors on human biology," concludes Duke University in a note disseminating its researchers' results.
"Parkinson's disease has been considered the fastest-growing neurological disorder in the world," explains Andrew West, professor in the Department of Pharmacology and Cancer Biology at Duke University School of Medicine and principal investigator of the new study. "Numerous lines of data suggest that environmental factors could play a prominent role in Parkinson's disease, but for the most part these factors have not been identified," says the co-author in statements released by his university.
It has been shown that plastics converted into waste or deteriorated by use (washing synthetic clothing or worn tires, for example) break into very small pieces and accumulate in water and food. Several studies published in recent months show, in this sense, that finally some of these residues can be found in blood and urine samples in humans.
"Our study suggests that the emergence of micro- and nanoplastics in the environment could represent a new toxic challenge with respect to the risk and progression of Parkinson's disease," West said. "This is especially concerning given the projected increase in concentrations of these contaminants in our water and food supplies."
West and his colleagues from Duke's Nicholas School of the Environment and the Department of Chemistry at Trinity College of Arts and Sciences found that plastic polystyrene nanoparticles, typically found in single-use items such as disposable cups and cutlery, They attract the buildup of the protein known as alpha-synuclein. West said the most surprising findings of the study are the tight bonds that form between the plastic and the protein within the area of the neuron where these clumps congregate, the lysosome.
The researchers said the plastic protein accumulations occurred in three different models conducted in the study: in test tubes, cultured neurons and mouse models of Parkinson's disease. West said questions remain about how such interactions could be occurring within humans and whether the type of plastic could affect the neuronal protein alterations observed.
"While microplastic and nanoplastic contaminants are being closely evaluated for their potential impact on cancer and autoimmune diseases, the surprising nature of the interactions we were able to observe in our models suggests the need to evaluate the rise of nanoplastic contaminants in the Parkinson's disease and the risk and progression of dementia," explains Professor West.
"The technology needed to monitor nanoplastics is still in the earliest possible stages and is not yet ready to answer all the questions we have," he said. “But hopefully efforts in this area will increase rapidly as we see what these particles can do in our models. “If we know what to pay attention to, we can take the necessary steps to protect ourselves, without compromising all the benefits we get every day from plastics,” says the lead author of this study, co-funded by the Michael J. Fox Foundation for Plastic Research. Parkinson's and the Aligning Science Across Parkinson's initiative.
