Numerous studies paint a picture of our world being inundated with tiny, inevitable microplastics. Once scientists started finding plastic particles in our own bodies, our guilt about finding them in the most remote areas of the planet turned into paranoia—they can affect our blood, organs, and even our brains, sparking a wave of scientific investigation.
But now, a growing number of people in the scientific community are raising significant doubts about these claims, The Guardian report, criticizing the methods used in some of the most famous papers behind it.
A study published in the journal natural medicine In February last year, they claimed to have documented an increase in micro and nanoplastics (MNPs) in human brain tissue through autopsies of preserved bodies that died between 1997 and 2024. But in November, another group of researchers questioned the findings in a letter published in the same journal, criticizing their “limited contamination controls and lack of validation steps.” The Guardian.
“The brain microplastic paper is a joke,” Dušan Materić, a co-author of the letter from the Helmholtz Center for Environmental Research in Germany, told the newspaper. “It is known that fats can cause false positives in polyethylene. The brain has [approximately] Sixty percent fat. “
In fact, Mattridge thinks rising obesity rates could explain the trend.
“That paper is really bad, and its errors are explainable,” he added, warning that “more than half of high-impact papers” had serious doubts about microplastics in tissues.
Popular methods for measuring the quality of micro- and nanoplastics raise a central question. Known as Py-GC-MS, it involves pyrolyzing the sample, or heating it in an oxygen-free environment until it evaporates. The smoke produced by this process is then separated and measured so that the properties of the original substance can be analyzed.
But it turns out that fats in human tissue can also produce the same smoke signature as materials used in microplastics like polyethylene. Although the study claims to chemically remove tissue before pyrolyzing the samples, critics wonder whether some traces could be left behind and produce false positives. This led Cassandra Rauert, an environmental chemist at the University of Queensland, to conclude in a January 2025 paper that Py-GC-MS “is currently not a suitable technique for identifying polyethylene or PVC due to persistent interferences.” The paper identified a total of 18 studies that did not properly consider the risk of false positives.
“I do think this is an issue across the field,” Lauter added The Guardian. “I think a lot of concentration [of MNPs] The situation reported is completely unrealistic. “
Another problem, says Frederic Béen of Vrije Universiteit Amsterdam, is that while there are guidelines in the field of analytical chemistry on how to analyze certain samples, for microplastics these guidelines do not yet exist.
“But we still see that very standard good laboratory practices that should be followed in a lot of papers are not necessarily followed,” he told us The Guardiansuch as measures to eliminate background contamination. “So you can’t be confident that everything you find doesn’t stem entirely or in part from some of these problems.”
The debate highlights the nascent stage of exploring the environmental and health impacts of microplastics, meaning it will take years of patient science to settle. Currently, experts are not sure how microplastics affect our health, nor have they been definitively proven to be harmful to us (although there is no shortage of research showing that they are). Still, no one should be upset by something with a plastic spoon in their head, but if doubters are to be believed, perhaps this claim deserves scrutiny, too.
“We do have plastic in our bodies — I think that’s for sure,” Mattridge said. “But the real hard evidence has yet to come.”
More information about microplastics: Doctors find evidence that microplastics can clog arteries, lead to heart disease and strokes
