Researchers have detected plastic particles in the liver, kidneys, and brain. However, the pathways through which these particles enter the body and their potential health effects remain unclear.
Plastic Particles Detected in Human Organs
It is no secret that global plastic waste continues to increase exponentially. Large quantities of plastic enter the environment, break down into microplastics, and can remain detectable for centuries. We already know that animals ingest or become entangled in plastic, that plastic bags have been discovered in the deep sea, and that microplastics are now found even in the Arctic.
For a long time, however, the human body appeared to be largely protected from this growing wave of plastic pollution. A study published in February 2025 challenges that assumption. Researchers found accumulations of micro- and nanoplastics in human liver, kidney, and brain tissue, raising new questions about how these particles enter the body and what effects they may have on human health.
Polyethylene, Polypropylene, and PVC Found in the Body
The study compared tissue samples from the liver, kidneys, and brain of individuals who died in 2016 with those of individuals who died in 2024. Using various methods to detect micro- and nanoplastics in tissue, researchers identified plastic particles in all three organs.
A clear difference emerged between the two groups. Significantly higher concentrations of micro- and nanoplastics were found in the organs of individuals who died in 2024.
Most of the particles consisted of polyethylene (PE), a plastic commonly used in shopping bags, plastic packaging, and food containers. Researchers also detected other polymers, primarily polypropylene (PP) and polyvinyl chloride (PVC).
A closer analysis of the 2024 samples revealed that concentrations of plastic particles in the brain were significantly higher than those found in the liver or kidneys. Researchers also observed consistently higher levels of micro- and nanoplastics in brain samples from individuals diagnosed with dementia compared with those without dementia.
Interestingly, the concentration of plastic particles did not appear to be linked to age, sex, place of origin, or cause of death. The most significant difference was related to the year of death, with the 2024 group showing noticeably higher concentrations of polyethylene and other polymers across all examined organs.
Microplastics and Human Health
The precise effects of micro- and nanoplastics on human health are still not fully understood. Research on mammals remains limited, and many questions remain unanswered.
In 2023, researchers examined the effects of PET nanoplastics on zebrafish embryos and found that tiny plastic particles accumulated in multiple organs, including the liver, intestines, kidneys, and brain. These accumulations were associated with behavioral changes and altered liver function.
Other studies have detected microplastics in the placentas of pregnant women and in human testicular tissue. As sperm counts and fertility rates have declined globally over recent decades, scientists are investigating whether exposure to plastic particles could be a contributing factor.
The February 2025 study also reported higher concentrations of micro- and nanoplastics in the brains of individuals with dementia. However, this does not necessarily mean that plastic particles cause dementia. Researchers note that dementia is often associated with a weakened blood-brain barrier and a reduced ability to remove harmful substances from the brain. As a result, the increased plastic accumulation may be a consequence of the disease rather than its cause.
How Do Microplastics Enter and Move Through the Body?
Micro- and nanoplastics have been detected in air, drinking water, and food, making exposure almost unavoidable for both humans and animals.
One of the most surprising findings of the study was the lack of a clear relationship between age and plastic concentrations in the body. Instead, the year of death appeared to be the more important factor. This suggests that the rising levels of microplastics in the environment may be reflected in increasing concentrations inside the human body.
The effect was particularly noticeable in brain tissue, where plastic concentrations increased by around 50% over an eight-year period.
Research on zebrafish embryos exposed to constant levels of nanoplastics found that accumulation reached a certain threshold before stabilizing. Higher environmental concentrations resulted in higher uptake, and after exposure ended, the fish were able to eliminate some of the particles again.
In humans, however, much remains unknown. Researchers still do not fully understand:
How micro- and nanoplastics enter the body
How they are transported to different organs
How particles cross into the brain
Whether they can be removed from the body over time
Some scientists believe it is possible that an equilibrium may exist between uptake, excretion, and environmental exposure levels, but further research is needed to confirm this.
Conclusion
The detection of micro- and nanoplastics in the liver, kidneys, and brain highlights how widespread plastic pollution has become. While the health implications remain uncertain, the findings underline the importance of better understanding how these particles enter, move through, and potentially accumulate within the human body.
Improving our knowledge of these processes, particularly in the brain, will be essential for assessing possible long-term health risks and understanding the broader consequences of our growing exposure to plastic pollution.