On the 3rd of February, the paper: "Bioaccumulation of microplastics in decedent human brains" was published in Nature Medecine:
It has since been shared by more than 450 news outlets, resulting in headlines such as "Alarming levels of microplastics found in human brains", or "Your brain tissue is 50% more plastic than in 2016", and of course... "The Human Brain May Contain as Much as a Spoon’s Worth of Microplastics, New Research Suggests".
Their results demonstrated that the average human brain contains no less than ~7 g of plastic, corresponding to a staggering 0.5 mass%. Concentrations slightly higher than observed in agricultural soils fed by sewage sludge and exposed to mulching films. Unbelievable results!
Such results should make any microplastics researcher stop and think to themselves 'wait a minute... something is off'.
And there's good reason to be skeptical.
As microplastics researcher and specialist in one of the study's applied techniques i.e. Py-GC-MS for nano/microplastics detection, Dr. Dusan Materic pointed out:
"Scientists don't have time to ask themselves hard questions!
The brain microplastic paper is a joke. Fat is known to make false-positive for PE - see missing high m/z ions in Py-GC-MS. The brain has ~60% fat."
In addition to Py-GC-MS, the study conducted infrared spectroscopy and visual microscopy. Unfortunately, these methods were also flawed. Materic summed it up:
"For many of us working in this field, unfortunately, this is more than just "some issues." Those who deal with complex organic matrices understand the limitations of the method and the consequences of errors on the final data—it’s a fundamental aspect of analytical measurement. The problem here is how they applied those three methods, as each was used incorrectly:
(a) Failing to detect higher MW ions for PE is an indication of a false positive.
(b) Using FTIR with low threshold matches increases the risk of false positives (by the way, FTIR only works on particles >10 µm, not nanoplastics).
(c) Using microscopy without chemical confirmation of plastic particles and presenting images of unconfirmed plastics is a misleading application of the method. Altogether, these flaws render their results and conclusions fundamentally incorrect at best."
Materic also referred to a 2025 study published in ACS: "Assessing the Efficacy of Pyrolysis–Gas Chromatography–Mass Spectrometry for Nanoplastic and Microplastic Analysis in Human Blood", which in the abstract states the following: "It was concluded that Py-GC-MS is currently not a suitable analysis method for PE and PVC in biological matrices due to the presence of interferences and nonspecific pyrolysis products. Furthermore, while it is plausible to detect some polymers in blood, the estimated exposure concentrations needed are approaching the detection limits of the technique."
...Curiously, PE and PVC constituted the vast majority of identified polymers in the brain...
As noted above, microplastics were also identified by FT-IR (Fourier Transform Infrared) spectroscopy. This method is spatially limited to particles >20 µm and presents the interpreter with absorption spectra of the vibrational states of molecular bonds. An FT-IR spectrum thus functions as a compounds' chemical fingerprint.
But as with all other analytical methods, the signal can be noisy. Matching a spectrum to a compound is carried out by spectral matching software. Often, an acceptable spectrum has a HQI (hit quality index) > 80%, while a good match is >90% - Yet, even HQIs > 80 and 90%, can be false positives - It is imperative that a trained interpreter validates the spectrum.
Once again this study falls short, accepting all spectra with HQIs > 60%.
One comment on Materic' post criticized his denouncement of this study:
"To call this research a “joke” is not appropriate in my opinion. While it is undoubtedly valuable- rather essential- for us as scientists to identify the shortcomings of novel science, it’s also essential to acknowledge the unique insight provided by new research. These researchers went through rigorous peer review and the hours they’ve spent in the laboratory and writing room putting this work together in good faith should be celebrated. No one paper will tell us everything we want to know about MNPs in the human body. No published paper is ever without blind spot or opportunity for additional analyses. This paper is one hell of a jumping-off point to explore the research gaps identified in the comments of this post and beyond."
To which Materic replied:
"My logic is this. In the abstract, the authors write: “Complementary methods for the robust detection of tissue MNPs, including... 'a,b,c'... confirm the presence of MNPs in human kidney, liver, and brain.”
However, this statement is misleading for each method:
a) The method overestimates and produces false positives.
b) The detection threshold was set too low.
c) The approach is inherently inconclusive, as it cannot reliably distinguish plastics from other particles.
I don’t see how this abstract claim holds up! Nothing "robust" was demonstrated—not even in a single method, let alone three. (Not to mention, there are no replicates.)
If this were a study on marine or other environmental samples, it would not pass peer review in a solid journal—yet somehow, for human samples, it does. Sorry to say, but this work is flawed (hard work there all right, but still flawed) and only provides ammunition to deniers, ultimately hindering future policy development."
Materic' closing argument highlights an issue that many microplastics researchers may relate to - The more groundbreaking the finding appears to be, the lower the requirement for QA/QC appear to be - Although it should be the other way around!
We've seen it before... Microplastics in the clouds.... Microplastics in blood.... I could go on. Alarmist research based on false premises damages our reputation as scientists. It's a clear-cut case of the boy who cried wolf!
One may speculate that this tendency is fueled by scientific journals' ambitions to generate traffic - and it's working - but it's undermining our own credibility. Nature should know better.
Materic underlines that "we expect nanoplastic to be present in the brain".
As nano/microplastic are considered ubiquitous pollutants, it is more than likely that nanoplastics exist in brain tissue - However, surely not at concentrations surpassing contaminated agricultural soils! Like Materic, I recognize the hard work that goes into conducting and publishing work like this. All research is flawed to some degree, but absurdities like these cross the line.
Most of the public still trusts our research, but I would not blame them if that trust erodes. Let's focus on conducting rigorous research rather than pursuing media attention.
Oskar Hagelskjær
Founder and CEO Microplastic Solution
Comentarios