Microplastics – defined as tiny plastic particles between 1 micrometre and 5 millimetres in size – are now ubiquitous in our environment. These particles are either created by the disintegration of larger plastic objects (secondary microplastics) or are deliberately manufactured for products such as cosmetics (primary microplastics). The spread of microplastics and its potential effects on humans and the environment are the subject of numerous studies, some of which are currently again delivering worrying results. Just a few months ago, this was the subject of our blog. In the meantime, various new research results have emerged that make the topic seem increasingly urgent:
- Microplastics in the human brain
A US research team found significantly more nano- and microplastics in the liver and brain of deceased people examined in 2024 than in samples taken in 2016. The levels were particularly high in the brain – up to 30 times higher than in the liver or kidneys. The most commonly found microplastics were made of polyethylene, which is used for films and bottles. The contamination was particularly high in twelve brain samples from 2019 to 2024 from people with a confirmed diagnosis of dementia: they contained between 12,000 and 48,000 micrograms of plastic per gram of tissue. However, the research group emphasises that their study does not prove a direct cause-and-effect relationship.
Nihart, AJ et al. Bioaccumulation of microplastics in decedent human brains. Nat Med 2025.
https://doi.org/10.1038/s41591-024–03453‑1
• Kidney damage caused by microplastics
A study in Communications Biology has examined how microplastics combined with benzo[a]pyrene (BaP) can damage the kidneys of mice. BaP is a polycyclic aromatic hydrocarbon (PAH) that is carcinogenic, can alter genetic material and has properties that are toxic to reproduction. In animals that consumed both microplastics and BaP in their drinking water, there was a disruption of fat metabolism in the kidneys and a specific type of cell death (ferroptosis). However, the actual damage probably did not occur directly in the kidneys, but rather through damage to the intestines, which made the intestinal wall more permeable. This caused harmful substances to enter the bloodstream from the intestines and thus to the kidneys. Microplastics served as a carrier for BaP into the body. The mechanisms uncovered could indicate potential risks, including for human health.
Zhang, Y et al Activation of gut metabolite ACSL4/LPCAT3 by microplastics in drinking water mediates ferroptosis via gut–kidney axis. Commun Biol 8, 211, 2025.
https://doi.org/10.1038/s42003-025–07641‑8
- Microplastics and neurological impairment in mice
Another study from January 2025 examined the effects of microplastics on the brains of mice. The results showed that microplastics can potentially clog blood vessels in the brains of mice. The affected mice moved less, had poorer orientation and less stamina. However, the results cannot be easily transferred from mice to humans due to differences in brain structure, the study authors wrote in the journal Science Advances.
Haipeng Huang et al. Microplastics in the bloodstream can induce cerebral thrombosis by causing cell obstruction and lead to neurobehavioral abnormalities. Sci. Adv. 11, eadr8243(2025).
https://www.science.org/doi/10.1126/sciadv.adr8243
It’s quite alarming to see all the new findings that are emerging. And that’s not all by a long shot. Find out more about how microplastics affect the air and water in our next blog!